阅读说明：本技术 保护膜形成用复合片及带保护膜的半导体芯片的制造方法 (Composite sheet for forming protective film and method for manufacturing semiconductor chip with protective film ) 是由 古野健太 米山裕之 于 2019-03-08 设计创作，主要内容包括：本发明提供一种保护膜形成用复合片,其包含具有基材的支撑片、与所述支撑片上所具备的热固性保护膜形成用膜,该基材具有-15℃下的损耗角正切(tanδ)为0.05以上、且80℃下的储能模量(G’)为35.0MPa以上的特性。(The present invention provides a composite sheet for forming a protective film, which comprises a support sheet having a base material having a loss tangent (tan) at-15 ℃ of 0.05 or more and a storage modulus (G') at 80 ℃ of 35.0MPa or more, and a film for forming a thermosetting protective film provided on the support sheet.)

1. A composite sheet for forming a protective film, comprising a support sheet having a base material, and a film for forming a thermosetting protective film provided on the support sheet,

the base material has a loss tangent (tan) at-15 ℃ of 0.05 or more and a storage modulus (G') at 80 ℃ of 35.0MPa or more.

2. The composite sheet for forming a protective film according to claim 1, wherein the base material has the following properties:

the substrate was cut into a long side of 110mm × and a short side of 22mm so that the MD or CD direction of the substrate was the long side direction, and the measurement pitch before heating was L₀The substrate was subjected to a load of 2.2g in a manner of about 100mm, heated at 130 ℃ for 2 hours in this state, then left to cool, and the measurement distance L after heating was measured at 23 ℃₁When the temperature of the water is higher than the set temperature,

the thermal expansion/contraction ratio X represented by the following formula (1) is not less than-3% and not more than + 3% when the base material is cut into long sides in the MD direction or in the CD direction,

X＝[(L₁-L₀)/L₀]×100···(1)。

3. the composite sheet for forming a protective film according to claim 1 or 2, wherein the support sheet further comprises an adhesive layer,

the composite sheet for forming a protective film comprises the base material, the adhesive layer, and the film for forming a thermosetting protective film laminated in this order.

4. The composite sheet for forming a protective film according to claim 3, wherein the adhesive layer is non-energy-ray-curable or energy-ray-curable.

5. The composite sheet for forming a protective film according to claim 3 or 4, wherein the adhesive layer has a thickness of 3 to 20 μm.

6. A method for manufacturing a semiconductor chip with a protective film, comprising:

laminating a semiconductor wafer on the film side of the thermosetting protective film forming composite sheet according to any one of claims 1 to 5 to produce a laminate;

irradiating the interior of the semiconductor wafer of the laminated body with laser light to form a modified layer in the interior of the semiconductor wafer;

heating and curing the film for forming a thermosetting protective film of the laminate to produce a protective film; and

the semiconductor wafer and the thermosetting protective film-forming film or the protective film are divided by cold-expanding the laminate at a temperature lower than normal temperature.

Technical Field

The present invention relates to a composite sheet for forming a protective film and a method for manufacturing a semiconductor chip with a protective film.

The present application claims priority based on japanese patent application No. 2018-043567, filed in japan on 3, 9, 2018, and the contents thereof are incorporated herein.

Background

In recent years, semiconductor devices have been manufactured using a mounting method called a flip-chip (face down) method. In the flip chip system, a semiconductor chip having electrodes such as bumps on a circuit surface is used, and the electrodes are bonded to a substrate. Therefore, a back surface opposite to the circuit surface of the semiconductor chip may be exposed.

A resin film containing an organic material as a protective film is formed on the back surface of the exposed semiconductor chip, and the resin film may be incorporated into a semiconductor device as a semiconductor chip with a protective film.

In order to prevent cracks from being generated on the semiconductor chip after the dicing process or the packaging, a protective film is used.

In order to form such a protective film, for example, a composite sheet for forming a protective film is used which is provided with a film for forming a protective film on a support sheet having a base material. In the composite sheet for forming a protective film, the film for forming a protective film can be cured to form a protective film, and the support sheet can be used as a dicing sheet, whereby the composite sheet for forming a protective film in which the film for forming a protective film and the dicing sheet are integrated can be produced.

As such a composite sheet for forming a protective film, a composite sheet for forming a protective film is used which is provided with a thermosetting film for forming a protective film which is cured by heating and thereby forms a protective film. For example, the composite sheet for forming a protective film is attached to the back surface (the surface opposite to the electrode-forming surface) of the semiconductor wafer with a thermosetting film for forming a protective film, the film for forming a protective film is cured by heating to form a protective film, and the semiconductor wafer is cut together with the protective film by dicing to form semiconductor chips. After that, the semiconductor chip is separated from the supporting sheet while maintaining the state of the protective film attached thereto, and is picked up. In addition, the protective film-forming film may be cured and cut in reverse order.

As a method of dividing a semiconductor wafer together with a protective film, a method of dicing a semiconductor wafer using a dicing blade is widely used, however, in recent years, various methods of dividing a semiconductor wafer without using a dicing blade have been studied. For example, the following methods are known: the semiconductor wafer is irradiated with laser light so as to be focused at a focal point set in the semiconductor wafer, thereby forming a modified layer in the semiconductor wafer, and then the semiconductor wafer on which the modified layer is formed and a resin film is attached to the back surface thereof is spread (expanded) in the planar direction of the resin film together with the resin film, thereby cutting the resin film, and the semiconductor wafer is divided and singulated (singulated) at the modified layer portion, thereby obtaining a semiconductor chip. For the planar expansion of the resin film, cold expansion (cold expansion) is studied under a low temperature condition of-15 ℃, for example, to favorably divide the resin film together with the semiconductor wafer.

The cold expansion based segmentation method, unlike the method using a cutting blade, has the following advantages: the semiconductor wafer is free from a cut portion caused by a dicing blade, and a larger number of semiconductor chips can be obtained from the semiconductor wafer without generating chips. As a substance for die bonding (dicing) of a semiconductor chip on a circuit formation surface of a substrate, there is a film-like adhesive, and the above-described dividing method has been mainly used so far when the film-like adhesive is used as the resin film (see patent documents 1 and 2).

Therefore, if the above-described dicing method by cold spreading is applied to a semiconductor wafer having a thermosetting protective film-forming film or a protective film as a cured product thereof as the resin film, such a method is extremely useful as a method for manufacturing a semiconductor chip having a protective film.

Disclosure of Invention

Technical problem to be solved by the invention

However, in the production process of semiconductor chips, when the dicing method of cold-expanding at a low temperature of-15 ℃ disclosed in patent documents 1 and 2 is applied to a semiconductor wafer having a film for forming a thermosetting protective film or a protective film as a cured product thereof, there is a problem that a supporting sheet is cracked, and in cold-expanding at a normal temperature of 15 to 25 ℃, there is a possibility that a dicing failure of the film for forming a thermosetting protective film and the protective film as a cured product thereof occurs. In the thermosetting protective film-forming film-heating curing step, the thermosetting protective film-forming film is heated and cured together with the support sheet in a state where a plurality of laminated bodies each having a semiconductor wafer or a semiconductor chip obtained by dicing thereof placed on the wafer-attaching portion of the protective film-forming composite sheet around the support by the annular frame are left standing with a minute gap in the case. When PE (polyethylene) having excellent cold resistance is used for the base material of the support sheet, the support sheet of the PE base material is bent when the thermosetting protective film forming film is cured by heating, and there is a problem that the wafer bonding portion of one protective film forming composite sheet comes into contact with the semiconductor wafer or semiconductor chip accommodated in the other protective film forming composite sheet therebelow.

Thus. The present invention provides a composite sheet for forming a protective film, which prevents a support sheet from being cracked due to cold expansion and prevents the support sheet from being bent even under a condition that a film for forming a thermosetting protective film is cured by heating, when a semiconductor chip with a protective film is manufactured by applying a dividing method based on cold expansion at a temperature lower than normal temperature and using the film for forming a thermosetting protective film, and a method for manufacturing a semiconductor chip with a protective film and a semiconductor device using the composite sheet for forming a protective film.

Means for solving the problems

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present application have found that the above-mentioned object can be achieved by using a composite sheet for forming a protective film, which has a loss tangent (tan) at low temperature and a storage modulus (G') at high temperature both of which are equal to or higher than predetermined values when measuring the dynamic viscoelasticity of a base material of a support sheet in the composite sheet for forming a protective film.

Namely, the present invention is as follows.

[1] A composite sheet for forming a protective film, which comprises a thermosetting film for forming a protective film on a support sheet having a base material,

the base material has a loss tangent (tan) at-15 ℃ of 0.05 or more and a storage modulus (G') at 80 ℃ of 35.0MPa or more, when measured for dynamic viscoelasticity.

[2]According to the above [1]The composite sheet for forming a protective film, wherein the base material is cut into a long side of 110mm × and a short side of 22mm so that the MD direction or CD direction of the base material is the long side direction, and the measurement pitch before heating is L₀The substrate was subjected to a load of 2.2g in a manner of about 100mm, heated at 130 ℃ for 2 hours in this state, then left to cool, and the measurement distance L after heating was measured at 23 ℃₁In the case where the base material is cut into long sides in the MD direction or the base material is cut into long sides in the CD direction, the thermal expansion/contraction ratio X represented by the formula (1) is not less than-3% and not more than + 3%.

X＝[(L₁-L₀)/L₀]×100···(1)

[3] The composite sheet for forming a protective film according to the above [1] or [2], wherein the support sheet has a base material and an adhesive layer, and the composite sheet for forming a protective film comprises the base material, the adhesive layer and the film for forming a protective film laminated in this order.

[4] The composite sheet for forming a protective film according to the above [3], wherein the adhesive layer is non-energy ray-curable or energy ray-curable.

[5] The composite sheet for forming a protective film according to the above [3] or [4], wherein the adhesive layer has a thickness of 3 to 20 μm.

[6] A method for manufacturing a semiconductor chip with a protective film, comprising:

a step of laminating a semiconductor wafer on the protective film-forming film side of the composite sheet for forming a protective film according to any one of [1] to [5] to prepare a laminate;

irradiating the inside of the semiconductor wafer with laser light to form a modified layer inside the semiconductor wafer;

a step of heating and curing the protective film-forming film to form a protective film; and

and a step of dividing the semiconductor wafer and the protective film or the protective film by cold-expanding the laminate at a temperature lower than the normal temperature.

That is, the present invention includes the following aspects.

[ 1' ] A composite sheet for forming a protective film, comprising a support sheet having a base material, and a film for forming a thermosetting protective film provided on the support sheet,

the base material has a loss tangent (tan) at-15 ℃ of 0.05 or more and a storage modulus (G') at 80 ℃ of 35.0MPa or more.

[2’]The composite sheet for forming a protective film according to claim 1, wherein the base material has a property that the base material is cut into a long side of 110mm × and a short side of 22mm so that the MD direction or the CD direction of the base material is the long side direction, and the measurement pitch before heating is L mm₀The substrate was subjected to a load of 2.2g in a manner of about 100mm, heated at 130 ℃ for 2 hours in this state, then left to cool, and the measurement distance L after heating was measured at 23 ℃₁When the temperature of the water is higher than the set temperature,

the thermal expansion/contraction ratio X represented by the following formula (1) is-3% or more and + 3% or less, regardless of whether the base material is cut into long sides in the MD direction or the base material is cut into long sides in the CD direction.

X＝[(L₁-L₀)/L₀]×100···(1)

[3 ' ] the composite sheet for forming a protective film according to [1 ' ] or [2 ' ], wherein the support sheet further comprises an adhesive agent layer,

the composite sheet for forming a protective film comprises the base material, the adhesive layer, and the film for forming a thermosetting protective film laminated in this order.

[4 '] the composite sheet for forming a protective film according to [ 3' ], wherein the adhesive layer is non-energy ray-curable or energy ray-curable.

[5 ' ] the composite sheet for forming a protective film according to [3 ' ] or [4 ' ], wherein the adhesive layer has a thickness of 3 to 20 μm.

[ 6' ] A method for manufacturing a semiconductor chip with a protective film, comprising:

laminating a semiconductor wafer on the thermosetting protective film-forming film side of the composite sheet for forming a protective film according to any one of [1 '] 1 to [ 5' ] to produce a laminate;

irradiating the interior of the semiconductor wafer of the laminated body with laser light to form a modified layer in the interior of the semiconductor wafer;

heating and curing the film for forming a thermosetting protective film of the laminate to produce a protective film; and

the semiconductor wafer and the thermosetting protective film-forming film or the protective film are divided by cold-expanding the laminate at a temperature lower than normal temperature.

Effects of the invention

According to the present invention, there can be provided a composite sheet for forming a protective film, which prevents a support sheet from being cracked due to cold expansion and which does not bend even under a condition where a film for forming a thermosetting protective film is cured by heating, when a semiconductor chip with a protective film is produced using a thermosetting protective film-forming film by a dividing method based on cold expansion at a temperature lower than normal temperature, and a method for producing a semiconductor chip with a protective film and a semiconductor device using the composite sheet for forming a protective film.

Drawings

Fig. 1 is a cross-sectional view schematically showing one embodiment of the composite sheet for forming a protective film of the present invention.

Fig. 2 is a cross-sectional view schematically showing another embodiment of the composite sheet for forming a protective film of the present invention.

Fig. 3 is a cross-sectional view schematically showing an example of a method for manufacturing a semiconductor chip with a protective film.

Fig. 4 is a cross-sectional view schematically showing another example of the method for manufacturing a semiconductor chip with a protective film.

Fig. 5 is a sectional view schematically showing a method of a cold resistance test of the composite sheet for forming a protective film.

Fig. 6 is a sectional view schematically showing a method of testing heat resistance of the composite sheet for forming a protective film.

Detailed Description

◎ composite sheet for forming protective film

The composite sheet for forming a protective film of the present invention comprises a support sheet having a base material having a loss tangent (tan) at-15 ℃ of 0.05 or more and a storage modulus (G') at 80 ℃ of 35.0MPa or more, and a film for forming a thermosetting protective film provided on the support sheet.

In the composite sheet for forming a protective film of the present invention, the loss tangent (tan) at-15 ℃ of the base material contained in the support sheet is 0.05 or more, the base material has good cold resistance, the support sheet does not crack due to cold expansion at a temperature lower than normal temperature, and the storage modulus (G') at 80 ℃ is 35.0MPa or more, so that the support sheet does not bend even under the condition that the thermosetting film-forming film is heated and cured, and even when the thermosetting film-forming film is heated and cured in a state that a plurality of sheets are left standing with a minute gap in the case, the wafer-attaching portion of one composite sheet for forming a protective film can be prevented from coming into contact with the semiconductor wafer or the semiconductor chip accommodated on the other composite sheet for forming a protective film therebelow.

In the composite sheet for forming a protective film of the present invention, it is preferable that the base material is cut into a long side of 110mm × and a short side of 22mm so that the MD direction (that is, the longitudinal direction) or the CD direction (that is, the width direction) of the base material is the longitudinal direction, and the measurement pitch before heating is L₀The substrate was subjected to a load of 2.2g in a manner of about 100mm, heated at 130 ℃ for 2 hours in this state, then left to cool, and the measurement distance L after heating was measured at 23 ℃₁In the case of cutting the substrate into long sides in the MD direction or cutting the substrate into long sides in the CD direction, the thermal expansion/contraction ratio X represented by the following formula (1) is not less than-3% and not more than + 3%.

X＝(L₁-L₀)/L₀×100···(1)

The thermal expansion/contraction ratio X is set to be-3% or more and + 3% or less, whereby the bending of the support sheet is reduced even under the condition of heat-curing the thermosetting protective film-forming film, or the thermal expansion/contraction ratio X is set to be-3% or more and + 3% or less even when the base material is cut into long sides in the MD direction or the base material is cut into long sides in the CD direction, whereby the support sheet is not extremely bent in a specific direction even under the condition of heat-curing the thermosetting protective film-forming film.

As one side, the thermal expansion and contraction rate X is preferably 0 to 2.2% or less.

In the present specification, the term "film for forming a thermosetting protective film" refers to a film before thermosetting, and the term "protective film" refers to a film obtained by curing a film for forming a thermosetting protective film.

In the present specification, the laminated structure is also referred to as a "composite sheet for forming a protective film" even after the thermosetting protective film-forming film is cured, as long as the laminated structure of the support sheet and the cured product of the thermosetting protective film-forming film (in other words, the support sheet and the protective film) is maintained.

In the present specification, "normal temperature" means a temperature at which cooling or heating is not particularly performed, that is, a normal temperature, and examples thereof include a temperature of 15 to 25 ℃.

"Cold spreading" refers to the application of a spreading force in a direction parallel to the surface of a semiconductor wafer at a temperature lower than normal temperature (e.g., -30 to 5 ℃).

Fig. 1 is a cross-sectional view schematically showing one embodiment of the composite sheet for forming a protective film of the present invention.

The composite sheet 1 for forming a protective film shown here includes a thermosetting film 13 for forming a protective film on one surface 10a of the support sheet 10. The support sheet 10 is formed by laminating a base material 11 and an adhesive layer 12, and has the adhesive layer 12 on one surface 11a of the base material 11, and a film 13 for forming a thermosetting protective film on the adhesive layer 12. The composite sheet 1 for forming a protective film further includes a release film 15 on the thermosetting protective film-forming film 13, and the release film 15 is removed when the composite sheet 1 for forming a protective film is used. The thermosetting protective film-forming film 13 becomes a protective film by thermosetting.

In the composite sheet 1 for forming a protective film, the adhesive layer 12 is laminated on the surface 11a of the substrate 11, and the film 13 for forming a thermosetting protective film is laminated on a part of the surface 12a of the adhesive layer 12 (that is, the surface of the adhesive layer 12 opposite to the surface thereof in contact with the substrate 11). Further, a release film 15 is laminated on the exposed surface of the thermosetting film-forming film 13 of the surface 12a of the adhesive layer 12 and the surface 13a of the thermosetting film-forming film 13 (the upper surface and the side surfaces, that is, the surface of the thermosetting film-forming film 13 which is not in contact with the adhesive layer 12).

The protective film-forming composite sheet is preferably a sheet that is transparent to laser light so that the sheet can be irradiated with laser light from the side of the sheet or a protective film obtained by thermally curing the sheet and laser-printed via a support sheet.

In the process of manufacturing a semiconductor chip with a protective film, the support sheet is preferably transparent to the laser light so that the semiconductor wafer can be irradiated with the laser light in the infrared region (which may be referred to as SD) from the support sheet side and the modified layer is formed inside the semiconductor wafer through the support sheet.

Further, in order to allow the laser light at the time of infrared inspection to pass through the support sheet and to enable easy inspection of the state of the semiconductor chip, that is, to inspect whether or not the thermosetting protective film forming film or the protective film is surely cut when the semiconductor wafer is divided and singulated from the formation site of the modified layer as a starting point by cold expanding (which may be referred to as CE) the semiconductor wafer, and to enable suppression of reduction in the manufacturing efficiency of the semiconductor device, it is preferable that the support sheet is transparent to the laser light at the time of infrared inspection and the thermosetting protective film forming film is colored. This makes it possible to easily inspect the state, that is, whether or not the thermosetting protective film-forming film or the protective film is reliably cut, and to suppress a decrease in the manufacturing efficiency of the semiconductor device.

Fig. 2 is a cross-sectional view schematically showing another embodiment of the composite sheet for forming a protective film of the present invention. In fig. 2, the same elements as those shown in fig. 1 are denoted by the same reference numerals as those in fig. 1, and detailed description thereof is omitted. This is also the same in the figures following fig. 2.

The composite sheet 2 for forming a protective film shown here is the same as the composite sheet 1 for forming a protective film shown in fig. 1 except that a thermosetting protective film-forming film 23 is laminated on the entire surface 12a of the adhesive layer 12, a jig adhesive layer 16 is laminated on a part of the surface 23a of the thermosetting protective film-forming film 23 (i.e., the surface of the thermosetting protective film-forming film 23 opposite to the surface thereof in contact with the adhesive layer 12), and a release film 15 is laminated on the exposed surface of the surface 23a of the thermosetting protective film-forming film 23 on which the jig adhesive layer 16 is not laminated and the surface 16a of the jig adhesive layer 16 (the upper surface and the side surfaces, i.e., the upper surface and the side surfaces of the jig adhesive layer 16 which are not in contact with the thermosetting protective film-forming film 23).

The composite sheet 2 for forming a protective film shown in fig. 2 is used in the following manner: in the state where the release film 15 is removed, the back surface of the semiconductor wafer (not shown) is attached to the front surface 23a of the thermosetting protective film forming film 23, and the upper surface of the front surface 16a of the jig adhesive layer 16 is attached to a jig such as a ring frame.

The composite sheet for forming a protective film of the present invention is not limited to the composite sheet for forming a protective film shown in fig. 1 to 2, and a part of the configuration of the composite sheet for forming a protective film shown in fig. 1 to 2 may be changed or deleted, or another configuration may be further added to the composite sheet for forming a protective film described so far, within a range that the effect of the present invention is not impaired.

The thermosetting protective film-forming film is cured by heating and serves as a protective film for protecting the back surface (the surface opposite to the electrode-forming surface) of the semiconductor wafer or the semiconductor chip, is soft and can be easily attached to an object to be attached, and has a tensile modulus (young's modulus) of elasticity of 1 × 10⁶～1×10⁸Pa or so.

On the other hand, the tensile elastic modulus (young's modulus) of the protective film obtained by heat curing was hardened to 1 × 10⁸～5.4×10⁹Pa or so.

The composite sheet for forming a protective film of the present invention is used for preparing a laminate including a support sheet, a film for forming a thermosetting protective film, and a semiconductor wafer in this order, the laminate being attached to the semiconductor wafer in a method for manufacturing a semiconductor chip with a protective film, which will be described later.

Hereinafter, each configuration of the composite sheet for forming a protective film of the present invention will be described in detail.

○ supporting sheet

The support sheet is not particularly limited as long as it is a base material and can be provided with the film for forming a thermosetting protective film, and examples thereof include a support sheet that functions as a dicing sheet or the like for protecting the surface of the film for forming a thermosetting protective film in a dicing step or the like.

Among the support sheets, preferred support sheets include a support sheet composed of only a base material, a support sheet obtained by laminating a base material and an adhesive layer, and the like, which are generally used in the field of a sheet for processing a semiconductor wafer.

The support sheet of the composite sheet for forming a protective film of the present invention may be a sheet composed of only a base material as one side surface, or may be a sheet composed of a base material and an adhesive layer provided on the base material as the other side surface.

The support sheet may be formed of one layer (single layer) or may be formed of a plurality of layers of two or more layers. When the support sheet is formed of a plurality of layers, the plurality of layers may be the same as or different from each other. That is, all the layers may be the same, all the layers may be different, or only some of the layers may be different. Also, when the plurality of layers are different from each other, the combination of the plurality of layers is not particularly limited. Here, the plurality of layers are different from each other means that at least one of the material and the thickness of each layer is different.

The thickness of the support sheet may be appropriately selected according to the purpose, and in view of sufficient flexibility that can be imparted to the composite sheet for forming a protective film, adhesion to a semiconductor wafer, and handling in producing the composite sheet for forming a protective film, the thickness of the support sheet is preferably 10 to 500 μm, more preferably 20 to 350 μm, and particularly preferably 30 to 200 μm.

Here, the "thickness of the support sheet" refers to the total thickness of the layers constituting the support sheet, and for example, in the case of a support sheet in which a substrate and an adhesive layer are laminated, the total value of the thickness of the substrate and the thickness of the adhesive layer is referred to.

In addition, at least one surface of the support sheet may be an uneven surface, and the thickness of the support sheet may be calculated from a starting point at which the tip of the convex portion is one side, at a portion of the uneven surface of the support sheet including the convex portion.

In the present specification, the term "thickness" refers to a value measured by a constant pressure thickness measuring instrument.

For the reasons described above, the support sheet is preferably transparent. However, the transparent layer may be opaque and may be colored according to the purpose as long as it is within a range in which the transmissivity of the wavelength of the predetermined laser beam and the checking property of whether or not the laser beam is cut off can be secured.

Specifically, the transmittance of light having a wavelength of 532nm in the support sheet is preferably 30% or more, more preferably 50% or more, and particularly preferably 70% or more. When the light transmittance is in such a range, the thermosetting protective film-forming film or the protective film can be irradiated with a laser beam through the support sheet, and printing can be performed more clearly.

On the other hand, the upper limit of the transmittance of light having a wavelength of 532nm in the support sheet is not particularly limited, and may be, for example, 95%.

The transmittance of light having a wavelength of 532nm in the support sheet is preferably 30% or more and 95% or less, more preferably 50% or more and 95% or less, and particularly preferably 70% or more and 95% or less.

The transmittance of light having a wavelength of 1064nm in the support sheet is preferably 30% or more, more preferably 50% or more, and particularly preferably 70% or more. When the semiconductor wafer is irradiated with the laser beam (SD) in the infrared region from the support sheet side, the laser beam in the infrared region can transmit through the support sheet to form a modified layer in the semiconductor wafer satisfactorily, and when the film for forming a thermosetting protective film or the protective film is irradiated with the laser beam through the support sheet to print the film, the print can be performed more clearly.

On the other hand, the upper limit of the transmittance of light having a wavelength of 1064nm in the support sheet is not particularly limited, and may be, for example, 95%.

The transmittance of light having a wavelength of 1064nm in the support sheet is preferably 30% or more and 95% or less, more preferably 50% or more and 95% or less, and particularly preferably 70% or more and 95% or less.

Next, each layer constituting the support sheet will be described in further detail.

Base material

The base material is in the form of a sheet or a film, and a polymer having excellent cold resistance with a loss tangent (tan) at-15 ℃ of 0.05 or more and excellent heat resistance with a storage modulus (G') at 80 ℃ of 35.0MPa or more is selected as a constituent material thereof. For example, a polymer having a high Tg (i.e., glass transition temperature) is considered to be relatively hard as a polymer having excellent heat resistance, and a polymer having a low Tg is considered to be soft as a polymer having excellent cold resistance. It is not easy to select a single polymer having sufficient cold resistance and heat resistance.

In the present invention, the loss tangent (tan) at-15 ℃ and the storage modulus (G') at 80 ℃ can be determined by the method described in < dynamic viscoelasticity measurement > below.

The loss tangent (tan) at-15 ℃ is preferably 0.05 to 0.13, more preferably 0.06 to 0.09. The storage modulus (G') at 80 ℃ is preferably 35.0MPa or more and 180MPa or less, more preferably 60MPa or more and 150MPa or less.

On one side, the loss tangent (tan) at-15 ℃ of the substrate of the protective film-forming composite sheet of the present invention is preferably 0.05 to 0.13, more preferably 0.06 to 0.09, and the storage modulus (G') at 80 ℃ is preferably 35.0MPa to 180MPa, more preferably 60MPa to 150 MPa.

As a constituent material of a base material having a loss tangent (tan) at-15 ℃ of 0.05 or more and a storage modulus (G') at 80 ℃ of 35.0MPa or more and sufficient both cold resistance and heat resistance, there can be mentioned a constituent material obtained by adding a soft component such as a resin having a low Tg to a heat-resistant resin in order to impart cold resistance to the resin (for example, polybutylene terephthalate to which a soft component is added); a constituent material modified by adding a rubber component to various heat-resistant resins in order to impart cold resistance thereto (for example, an olefin-based thermoplastic elastomer (TPO)); and a two-layer or three-layer material formed by laminating a heat-resistant resin layer and a cold-resistant resin layer.

The heat-resistant resin may have a storage modulus (G') at 80 ℃ of 35.0MPa or more, and examples thereof include polypropylene (which may be abbreviated as PP), polybutylene terephthalate (which may be abbreviated as PBT), and the like.

The resin having cold resistance may have a loss tangent (tan) at-15 ℃ of 0.05 or more, and examples thereof include polyethylene (sometimes abbreviated as PE) such as low density polyethylene (sometimes abbreviated as L DPE), linear low density polyethylene (sometimes abbreviated as LL DPE), and high density polyethylene (sometimes abbreviated as HDPE).

Examples of the resin that can be used as a base material of the resin having cold resistance include polyolefins other than polyethylene, such as polybutylene, polybutadiene, polymethylpentene, and norbornene resins; ethylene copolymers (that is, copolymers obtained using ethylene as a monomer) such as ethylene-vinyl acetate copolymers, ethylene- (meth) acrylic acid ester copolymers, and ethylene-norbornene copolymers; vinyl chloride-based resins (i.e., resins obtained using vinyl chloride as a monomer) such as polyvinyl chloride and vinyl chloride copolymers; polystyrene; a polycycloolefin; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polyethylene 2, 6-naphthalate, and wholly aromatic polyesters having an aromatic ring group in all the constituent units; copolymers of two or more of said polyesters; poly (meth) acrylates; a polyurethane; a urethane acrylate; a polyimide; a polyamide; a polycarbonate; a fluororesin; a polyacetal; modified polyphenylene ether; polyphenylene sulfide; polysulfones; polyether ketones, and the like.

In the present specification, "(meth) acrylic acid" is a concept including both "acrylic acid" and "methacrylic acid". The same applies to similar terms as for (meth) acrylic acid.

The resin constituting the base material may be one kind only, or two or more kinds, and in the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

The thickness of the base material is preferably 15 to 300 μm, preferably 50 to 200 μm, and more preferably 60 to 150 μm. By setting the thickness of the base material within such a range, the flexibility of the composite sheet for forming a protective film and the adhesiveness to a semiconductor wafer or a semiconductor chip can be further improved.

Here, the "thickness of the substrate" refers to the thickness of the entire substrate, and for example, the thickness of the substrate composed of a plurality of layers refers to the total thickness of all the layers constituting the substrate.

The substrate may be composed of one layer (single layer) or a plurality of layers of two or more layers, and when composed of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited.

When the substrate is composed of a plurality of layers, the total thickness of the layers may be set to the preferred thickness of the substrate.

When the adhesive layer is provided on the substrate, the surface of the substrate provided with the adhesive layer (which may be referred to as the substrate surface) preferably has a surface roughness Ra of 0.001 to 0.1. mu.m, more preferably 0.005 to 0.08. mu.m, and particularly preferably 0.01 to 0.04. mu.m. By setting the surface roughness Ra of the base material surface to the upper limit or less, the laser printing can be performed more clearly on the protective film.

The surface roughness Ra of the substrate surface can be adjusted, for example, according to the molding conditions, surface treatment conditions, and the like of the substrate.

As a method for singulating a semiconductor wafer into semiconductor chips, the following methods can be mentioned: the semiconductor wafer is divided and singulated from a portion where a modified layer is formed by irradiating the semiconductor wafer with a laser beam in an infrared region so as to focus on a focal point set in the semiconductor wafer, and then applying a force to the semiconductor wafer.

When the surface roughness Ra of the substrate surface is, for example, 0.01 to 0.2 μm, the composite sheet for forming a protective film comprising such a substrate is suitably used in the case where a modified layer is formed inside the semiconductor wafer and the semiconductor wafer is singulated.

On the other hand, the surface roughness Ra of the surface (back surface) of the base opposite to the surface (front surface) provided with the adhesive layer, in other words, the surface (back surface of the base) of the support sheet opposite to the surface (front surface) provided with the film for forming a thermosetting protective film (which may be referred to as the back surface of the base), is preferably 0.001 to 4 μm, more preferably 0.005 to 3.7 μm, even more preferably 0.01 to 3.4 μm, and particularly preferably 0.02 to 3.1 μm. When the surface roughness Ra of the back surface of the base material is equal to or less than the upper limit value, the surface roughness Ra of the surface opposite to the side in contact with the support sheet can be more easily reduced, and when the semiconductor wafer is irradiated with the laser light (SD) in the infrared region from the support sheet side, the laser light in the infrared region can transmit through the support sheet to favorably form the modified layer in the interior of the semiconductor wafer, and the laser printing can be more easily performed clearly on the protective film.

The surface roughness Ra of the back surface of the base material can be adjusted, for example, according to the molding conditions, surface treatment conditions, and the like of the base material.

The resin as a material of the base material may be a crosslinked resin.

The resin as a material of the base material may be a resin formed into a sheet by extrusion molding of a thermoplastic resin, may be a stretched resin, or may be a resin formed into a sheet by thinning and curing a curable resin by a known means.

The substrate may be colored or may be printed.

The base material preferably contains polypropylene from the viewpoint of having cold expansion suitability due to excellent heat resistance and appropriate flexibility, and also having good pickup suitability.

The polypropylene-containing substrate may be, for example, a single-layer or multi-layer substrate composed of only polypropylene, or may be a multi-layer substrate composed of a polypropylene layer and a resin layer other than polypropylene.

As one side, the base material of the composite sheet for forming a protective film of the present invention is preferably a film made of polybutylene terephthalate to which a soft component is added, a three-layer transparent film made of a mixed resin of polypropylene (PP) and an olefinic thermoplastic elastomer (which may be abbreviated as TPO), or a three-layer transparent film of Polyethylene (PE)/polypropylene (PP)/Polyethylene (PE).

The composite sheet for forming a protective film of the present invention can effectively suppress the bending of the support sheet even under the condition where the thermosetting film for forming a protective film is cured by heating by imparting heat resistance to the base material.

The substrate is preferably a substrate having high precision of thickness, that is, a substrate in which variation in thickness is suppressed at any portion. Among the above-mentioned constituent materials, those usable as a material constituting such a base material with high thickness accuracy include, for example, polyethylene, polyolefins other than polyethylene, polyethylene terephthalate, ethylene-vinyl acetate copolymers, and the like.

The base material may contain various known additives such as a filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, and a softener (plasticizer) in addition to the main constituent materials such as the resin.

The optical characteristics of the base material may be satisfied as long as the optical characteristics of the support sheet described above are satisfied. That is, the base material may be transparent or opaque, may be colored according to the purpose, or may be vapor-deposited with another layer.

In order to improve adhesion to other layers such as an adhesive layer provided thereon, the surface of the base material may be subjected to an oxidation treatment such as a roughening treatment by sandblasting treatment, solvent treatment, or the like, a corona discharge treatment, an electron beam irradiation treatment, a plasma treatment, an ozone/ultraviolet irradiation treatment, a flame treatment, a chromic acid treatment, or a hot air treatment.

In addition, the surface of the substrate may be primed.

When the antistatic coating layer or the composite sheet for forming a plurality of protective films are stacked and stored, the base material may have a layer for preventing the base material from adhering to another sheet or a suction table.

The substrate can be produced by a known method. For example, a resin-containing substrate can be produced by molding a resin composition containing the resin.

Adhesive layer

The adhesive layer is in a sheet or film shape and contains an adhesive.

Examples of the adhesive include adhesive resins such as acrylic resins, urethane resins, rubber resins, silicone resins, epoxy resins, polyvinyl ethers, polycarbonates, and ester resins, and acrylic resins are preferred.

In the present invention, the "adhesive resin" is a concept including both a resin having adhesiveness and a resin having adhesiveness, and includes, for example, not only a resin having adhesiveness of the resin itself but also a resin exhibiting adhesiveness by being used together with other components such as an additive, a resin exhibiting adhesiveness by the presence of an inducer (trigger) such as heat or water, and the like.

The adhesive layer may be composed of one layer (single layer) or a plurality of layers of two or more layers, and in the case of being composed of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited.

The thickness of the adhesive layer is preferably 1 to 100 μm, more preferably 1 to 60 μm, still more preferably 1 to 30 μm, and particularly preferably 3 to 20 μm.

Here, the "thickness of the adhesive agent layer" refers to the thickness of the entire adhesive agent layer, and for example, the thickness of the adhesive agent layer composed of a plurality of layers refers to the total thickness of all the layers constituting the adhesive agent layer.

The optical properties of the adhesive layer may be satisfied as long as the optical properties of the support sheet described above are satisfied. That is, the adhesive layer may be transparent or opaque, and may be colored according to the purpose.

The adhesive layer may be formed using an energy ray-curable adhesive, or may be formed using a non-energy ray-curable adhesive. The adhesive layer formed using the energy ray-curable adhesive can easily adjust physical properties before and after curing.

In the present invention, the "energy ray" refers to an energy ray having an energy quantum in an electromagnetic wave or a charged particle beam, and examples thereof include ultraviolet rays, radiation, electron beams, and the like.

The ultraviolet rays can be irradiated by using, for example, a high-pressure mercury lamp, a fusion lamp (fusion lamp), a xenon lamp, a black light lamp, an L ED lamp, or the like as an ultraviolet ray source.

In the present invention, "energy ray-curable property" refers to a property of curing by irradiation with an energy ray, and "non-energy ray-curable property" refers to a property of not curing even by irradiation with an energy ray.

Adhesive composition

The adhesive layer can be formed using an adhesive composition containing an adhesive. For example, an adhesive layer can be formed at a target site by applying an adhesive composition to a surface to be formed of the adhesive layer and drying the adhesive composition as necessary. More specific methods for forming the adhesive layer will be described in detail later together with methods for forming other layers. The content ratio of the components that do not vaporize at normal temperature in the adhesive composition is generally the same as the content ratio of the components in the adhesive layer.

In the present specification, "normal temperature" means a temperature at which cooling or heating is not particularly performed, that is, a normal temperature, and examples thereof include a temperature of 15 to 25 ℃.

The adhesive composition may be applied by a known method. Examples of the method include a method using various coaters such as a knife coater, a blade coater, a bar coater, a gravure coater, a roll coater, a curtain coater, a die coater, a knife coater, a screen coater, a meyer bar coater, and a kiss coater.

The drying conditions of the adhesive composition are not particularly limited. However, when the adhesive composition contains a solvent described later, it is preferably dried by heating. In this case, the drying is preferably performed at 70 to 130 ℃ for 10 seconds to 5 minutes, for example.

When the adhesive layer is energy ray-curable, examples of the adhesive composition containing an energy ray-curable adhesive, i.e., the energy ray-curable adhesive composition, include an adhesive composition (I-1) containing a non-energy ray-curable adhesive resin (I-1a) (hereinafter, this may be abbreviated as "adhesive resin (I-1 a)") and an energy ray-curable compound; an adhesive composition (I-2) comprising an energy ray-curable adhesive resin (I-2a) having an unsaturated group introduced into a side chain of a non-energy ray-curable adhesive resin (I-1a) (hereinafter, this may be abbreviated as "adhesive resin (I-2 a)"); and an adhesive composition (I-3) comprising the adhesive resin (I-2a) and an energy ray-curable compound.

< adhesive composition (I-1) >

As described above, the adhesive composition (I-1) contains the non-energy ray-curable adhesive resin (I-1a) and the energy ray-curable compound.

[ adhesive resin (I-1a) ]

The adhesive resin (I-1a) is preferably an acrylic resin.

Examples of the acrylic resin include an acrylic polymer having at least a structural unit derived from an alkyl (meth) acrylate.

The acrylic resin may have only one kind of structural unit, or two or more kinds of structural units, and when two or more kinds of structural units are present, the combination and ratio thereof may be arbitrarily selected.

Examples of the alkyl (meth) acrylate include alkyl (meth) acrylates in which the alkyl group constituting the alkyl ester has 1 to 20 carbon atoms. The alkyl group is preferably linear or branched.

More specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (also referred to as lauryl (meth) acrylate), tridecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Tetradecyl (meth) acrylate (also referred to as myristyl (meth) acrylate), pentadecyl (meth) acrylate, hexadecyl (meth) acrylate (also referred to as palmityl (meth) acrylate), heptadecyl (meth) acrylate, octadecyl (meth) acrylate (also referred to as stearate (meth) acrylate), nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like.

Preferably, the acrylic polymer has a structural unit derived from an alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group, from the viewpoint of improving the adhesive force of the adhesive agent layer. Further, the number of carbon atoms of the alkyl group is preferably 4 to 12, more preferably 4 to 8, from the point of further improving the adhesive force of the adhesive agent layer. The alkyl (meth) acrylate in which the alkyl group has 4 or more carbon atoms is preferably an alkyl acrylate.

The acrylic polymer preferably further has a structural unit derived from a functional group-containing monomer in addition to a structural unit derived from an alkyl (meth) acrylate.

Examples of the functional group-containing monomer include a functional group-containing monomer in which the functional group reacts with a crosslinking agent described later to form a crosslinking starting point, or in which the functional group reacts with an unsaturated group in an unsaturated group-containing compound described later to introduce an unsaturated group into a side chain of an acrylic polymer.

Examples of the functional group in the functional group-containing monomer include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group.

That is, examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; and non (meth) acrylic unsaturated alcohols (unsaturated alcohols having no (meth) acryloyl skeleton) such as vinyl alcohol and allyl alcohol.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids (i.e., monocarboxylic acids having an ethylenically unsaturated bond) such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids (i.e., dicarboxylic acids having an ethylenically unsaturated bond) such as fumaric acid, itaconic acid, maleic acid, and citraconic acid; anhydrides of said ethylenically unsaturated dicarboxylic acids; and carboxyalkyl (meth) acrylates such as 2-carboxyethyl methacrylate.

The functional group-containing monomer is preferably a hydroxyl group-containing monomer or a carboxyl group-containing monomer, and more preferably a hydroxyl group-containing monomer.

The functional group-containing monomer constituting the acrylic polymer may be only one kind, or two or more kinds. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

In the acrylic polymer, the content of the structural unit derived from the functional group-containing monomer is preferably 1 to 35% by mass, more preferably 2 to 32% by mass, and particularly preferably 3 to 30% by mass, based on the total amount (total mass) of the structural units.

The acrylic polymer may further have a structural unit derived from another monomer in addition to the structural unit derived from the alkyl (meth) acrylate and the structural unit derived from the functional group-containing monomer.

The other monomer is not particularly limited as long as it is copolymerizable with the alkyl (meth) acrylate and the like.

Examples of the other monomer include styrene, α -methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

The other monomer constituting the acrylic polymer may be only one type, or two or more types. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The acrylic polymer can be used as the above-mentioned non-energy ray-curable adhesive resin (I-1 a).

On the other hand, a product obtained by reacting an unsaturated group-containing compound having an energy ray-polymerizable unsaturated group (energy ray-polymerizable group) with a functional group in the acrylic polymer can be used as the energy ray-curable adhesive resin (I-2 a).

The adhesive resin (I-1a) contained in the adhesive composition (I-1) may be one type or two or more types. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the adhesive resin (I-1a) in the adhesive composition (I-1) is preferably 5 to 99% by mass, more preferably 10 to 95% by mass, and particularly preferably 15 to 90% by mass, based on the total mass of the adhesive composition (I-1).

[ energy ray-curable Compound ]

Examples of the energy ray-curable compound contained in the adhesive composition (I-1) include a monomer or oligomer having an energy ray-polymerizable unsaturated group and curable by irradiation with an energy ray.

Examples of the monomer in the energy ray-curable compound include polyvalent (meth) acrylates such as trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 4-butanediol di (meth) acrylate, and 1, 6-hexanediol (meth) acrylate; urethane (meth) acrylate; polyester (meth) acrylates; polyether (meth) acrylates; epoxy (meth) acrylates, and the like.

Examples of the oligomer in the energy ray-curable compound include oligomers obtained by polymerizing the monomers exemplified above.

The energy ray-curable compound is preferably urethane (meth) acrylate or urethane (meth) acrylate oligomer in terms of a large molecular weight and a low tendency to decrease the storage modulus of the adhesive layer.

The energy ray-curable compound contained in the adhesive composition (I-1) may be only one kind, or two or more kinds. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

In the adhesive composition (I-1), the content of the energy ray-curable compound is preferably 1 to 95% by mass, more preferably 5 to 90% by mass, and particularly preferably 10 to 85% by mass, based on the total mass of the adhesive composition (I-1).

[ crosslinking agent ]

When the acrylic polymer having a structural unit derived from a functional group-containing monomer in addition to a structural unit derived from an alkyl (meth) acrylate is used as the adhesive resin (I-1a), it is preferable that the adhesive composition (I-1) further contains a crosslinking agent.

The crosslinking agent crosslinks the adhesive resin (I-1a), for example, by reacting with the functional group.

Examples of the crosslinking agent include isocyanate-based crosslinking agents (i.e., crosslinking agents having an isocyanate group) such as toluene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and adducts of these diisocyanates; epoxy crosslinking agents (i.e., crosslinking agents having a glycidyl group) such as ethylene glycol glycidyl ether; aziridine crosslinking agents (i.e., crosslinking agents having an aziridinyl group) such as Hexa [1- (2-methyl) -azidinyl ] triphosphazine ] tris (1- (2-methyl) -azidinyl) triphosphate; metal chelate crosslinking agents (i.e., crosslinking agents having a metal chelate structure) such as aluminum chelates; an isocyanurate-based crosslinking agent (i.e., a crosslinking agent having an isocyanurate skeleton), and the like.

The crosslinking agent is preferably an isocyanate-based crosslinking agent in view of improving the cohesive force of the adhesive agent to improve the adhesive force of the adhesive agent layer, and easy availability.

The adhesive composition (I-1) may contain only one kind of crosslinking agent, or may contain two or more kinds of crosslinking agents. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the crosslinking agent in the adhesive composition (I-4) is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.3 to 15 parts by mass, relative to 100 parts by mass of the content of the adhesive resin (I-1 a).

[ photopolymerization initiator ]

The adhesive composition (I-1) may further contain a photopolymerization initiator. Even when the adhesive composition (I-1) containing a photopolymerization initiator is irradiated with a relatively low energy ray such as ultraviolet ray, the curing reaction proceeds sufficiently.

Examples of the photopolymerization initiator include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, and benzoin dimethyl ketal, acylphosphine oxide compounds such as acetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-dimethoxy-1, 2-diphenylethane-1-one, acylphosphine oxide compounds such as phenylbis (2,4, 6-trimethylbenzoyl) phosphine oxide and 2,4, 6-trimethylbenzoyl diphenylphosphine oxide, sulfur compounds such as benzylphenyl sulfide and tetramethylthiuram monosulfide, α -ketol compounds such as 1-hydroxycyclohexylphenyl ketone, azo compounds such as azobisisobutyronitrile, titanocene compounds such as titanocene, thioxanthone compounds such as thioxanthone, peroxide compounds, diketone compounds such as butanedione, benzophenone, benzoin, 2-4-diethylthioxanthone, 2-diethylthioxanthone, 2- [1- (2-methyl) methyl ] methyl ketone, and 2- (2-chloro) methyl) acetone.

Further, as the photopolymerization initiator, for example, quinone compounds such as 1-chloroanthraquinone; photosensitizers such as amines, and the like.

The pressure-sensitive adhesive composition (I-1) may contain only one kind of photopolymerization initiator, or may contain two or more kinds of photopolymerization initiators. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

In the adhesive composition (I-1), the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass, more preferably 0.03 to 10 parts by mass, and particularly preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the content of the energy ray-curable compound.

[ other additives ]

The adhesive composition (I-1) may further contain other additives not belonging to any of the above-mentioned components within a range not impairing the effects of the present invention.

Examples of the other additives include known additives such as antistatic agents, antioxidants, softeners (plasticizers), fillers (fillers), rust inhibitors, colorants (pigments and dyes), sensitizers, tackifiers, reaction retarders, and crosslinking accelerators (catalysts).

The reaction retarder is an additive which suppresses the undesired crosslinking reaction in the adhesive composition (I-1) during storage, for example, by the action of a catalyst mixed in the adhesive composition (I-1). Examples of the reaction retarder include a reaction retarder which forms a chelate complex (chelate complex) by using a chelate to a catalyst. More specifically, a reaction retarder having two or more carbonyl groups (-C (═ O) -) in one molecule is exemplified.

The adhesive composition (I-1) may contain only one kind of other additive, or may contain two or more kinds of other additives. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the other additives in the adhesive composition (I-1) is not particularly limited, and may be appropriately selected depending on the kind thereof.

[ solvent ]

The adhesive composition (I-1) may contain a solvent. By containing the solvent, the coating suitability of the adhesive composition (I-1) to the surface to be coated is improved.

Preferably, the solvent is an organic solvent. Examples of the organic solvent include ketones such as methyl ethyl ketone and acetone; esters (i.e., carboxylic acid esters) such as ethyl acetate; ethers such as tetrahydrofuran and dioxane; aliphatic hydrocarbons such as cyclohexane and n-hexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as 1-propanol and 2-propanol.

The solvent may be used in the adhesive composition (I-1) without removing the solvent used in the production of the adhesive resin (I-1a) from the adhesive resin (I-1a), or a solvent which is the same as or different from the solvent used in the production of the adhesive resin (I-1a) may be added separately in the production of the adhesive composition (I-1).

The adhesive composition (I-1) may contain only one kind of solvent, or may contain two or more kinds of solvents. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the solvent in the adhesive composition (I-1) is not particularly limited, and may be appropriately adjusted.

< adhesive composition (I-2) >

As described above, the adhesive composition (I-2) contains the energy ray-curable adhesive resin (I-2a) in which an unsaturated group is introduced into the side chain of the non-energy ray-curable adhesive resin (I-1 a).

[ adhesive resin (I-2a) ]

The adhesive resin (I-2a) is obtained, for example, by reacting an unsaturated group-containing compound having an energy ray-polymerizable unsaturated group with a functional group in the adhesive resin (I-1 a).

The unsaturated group-containing compound is a compound having, in addition to the energy ray-polymerizable unsaturated group, a group that can be bonded to the adhesive resin (I-1a) by reacting with a functional group in the adhesive resin (I-1 a).

Examples of the energy ray-polymerizable unsaturated group include a (meth) acryloyl group, a vinyl group (also referred to as an ethylene group), and an allyl group (also referred to as a 2-propenyl group). (meth) acryloyl is preferred.

Examples of the group that can be bonded to the functional group in the adhesive resin (I-1a) include an isocyanate group and a glycidyl group that can be bonded to a hydroxyl group or an amino group, and a hydroxyl group and an amino group that can be bonded to a carboxyl group or an epoxy group.

Examples of the unsaturated group-containing compound include (meth) acryloyloxyethyl isocyanate, (meth) acryloyl isocyanate, and glycidyl (meth) acrylate.

The adhesive resin (I-2a) contained in the adhesive composition (I-2) may be one type or two or more types. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

In the adhesive composition (I-2), the content of the adhesive resin (I-2a) is preferably 5 to 99% by mass, more preferably 10 to 95% by mass, and particularly preferably 10 to 90% by mass, based on the total mass of the adhesive composition (I-2).

[ crosslinking agent ]

For example, when the acrylic polymer having a structural unit derived from a functional group-containing monomer, which is the same as that in the adhesive resin (I-1a), is used as the adhesive resin (I-2a), the adhesive composition (I-2) may further contain a crosslinking agent.

The crosslinking agent in the adhesive composition (I-2) may be the same crosslinking agent as that in the adhesive composition (I-1).

The crosslinking agent contained in the adhesive composition (I-2) may be one kind only, or two or more kinds, and in the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

The content of the crosslinking agent in the adhesive composition (I-2) is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.3 to 15 parts by mass, relative to 100 parts by mass of the content of the adhesive resin (I-2 a).

[ photopolymerization initiator ]

The adhesive composition (I-2) may further contain a photopolymerization initiator. Even when the adhesive composition (I-2) containing a photopolymerization initiator is irradiated with a relatively low energy ray such as ultraviolet ray, the curing reaction proceeds sufficiently.

The photopolymerization initiator in the adhesive composition (I-2) may be the same photopolymerization initiator as that in the adhesive composition (I-1).

The pressure-sensitive adhesive composition (I-2) may contain only one kind of photopolymerization initiator, or may contain two or more kinds of photopolymerization initiators. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the photopolymerization initiator in the adhesive composition (I-2) is preferably 0.01 to 20 parts by mass, more preferably 0.03 to 10 parts by mass, and particularly preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the content of the adhesive resin (I-2 a).

[ other additives ]

The adhesive composition (I-2) may further contain other additives not included in any of the above components within a range not impairing the effects of the present invention.

Examples of the other additives in the adhesive composition (I-2) include the same other additives as those in the adhesive composition (I-1).

The adhesive composition (I-2) may contain only one kind of other additive, or may contain two or more kinds of other additives. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the other additives in the adhesive composition (I-2) is not particularly limited, and may be appropriately selected depending on the kind thereof.

[ solvent ]

The adhesive composition (I-2) may also contain a solvent for the same purpose as in the case of the adhesive composition (I-1).

The solvent in the adhesive composition (I-2) may be the same solvent as that in the adhesive composition (I-1).

The adhesive composition (I-2) may contain only one kind of solvent, or may contain two or more kinds of solvents. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the solvent in the adhesive composition (I-2) is not particularly limited, and may be appropriately adjusted.

< adhesive composition (I-3) >

As described above, the adhesive composition (I-3) contains the adhesive resin (I-2a) and an energy ray-curable compound.

In the adhesive composition (I-3), the content of the adhesive resin (I-2a) is preferably 5 to 99% by mass, more preferably 10 to 95% by mass, and particularly preferably 15 to 90% by mass, based on the total mass of the adhesive composition (I-3).

[ energy ray-curable Compound ]

Examples of the energy ray-curable compound contained in the adhesive composition (I-3) include a monomer or oligomer having an energy ray-polymerizable unsaturated group and curable by irradiation with an energy ray, and examples of the energy ray-curable compound include the same energy ray-curable compounds as those contained in the adhesive composition (I-1).

The energy ray-curable compound contained in the adhesive composition (I-3) may be only one kind, or two or more kinds. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The content of the energy ray-curable compound in the adhesive composition (I-3) is preferably 0.01 to 300 parts by mass, more preferably 0.03 to 200 parts by mass, and particularly preferably 0.05 to 100 parts by mass, relative to 100 parts by mass of the content of the adhesive resin (I-2 a).

[ photopolymerization initiator ]

The adhesive composition (I-3) may further contain a photopolymerization initiator. Even when the adhesive composition (I-3) containing a photopolymerization initiator is irradiated with a relatively low energy ray such as ultraviolet ray, the curing reaction proceeds sufficiently.

The photopolymerization initiator in the adhesive composition (I-3) may be the same photopolymerization initiator as that in the adhesive composition (I-1).

The photopolymerization initiator contained in the pressure-sensitive adhesive composition (I-3) may be only one kind, or two or more kinds, and in the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

In the adhesive composition (I-3), the content of the photopolymerization initiator is preferably 0.01 to 20% by mass, more preferably 0.03 to 10% by mass, and particularly preferably 0.05 to 5% by mass, based on 100 parts by mass of the total content of the adhesive resin (I-2a) and the energy ray-curable compound.

[ other additives ]

The adhesive composition (I-3) may further contain other additives not belonging to any of the above-mentioned components within a range not impairing the effects of the present invention.

Examples of the other additives include the same other additives as those in the adhesive composition (I-1).

The adhesive composition (I-3) may contain only one other additive, or may contain two or more other additives, and when two or more other additives are contained, the combination and ratio of these additives may be arbitrarily selected.

The content of the other additives in the adhesive composition (I-3) is not particularly limited, and may be appropriately selected depending on the kind thereof.

[ solvent ]

The adhesive composition (I-3) may further contain a solvent for the same purpose as in the case of the adhesive composition (I-1).

Examples of the solvent in the adhesive composition (I-3) include the same solvents as those in the adhesive composition (I-1).

The adhesive composition (I-3) may contain only one solvent, or may contain two or more solvents, and when two or more solvents are contained, the combination and ratio of the solvents can be arbitrarily selected.

The content of the solvent in the adhesive composition (I-3) is not particularly limited, and may be appropriately adjusted.

< adhesive compositions other than the adhesive compositions (I-1) to (I-3) >

Although the adhesive composition (I-1), the adhesive composition (I-2) and the adhesive composition (I-3) have been mainly described so far, the components described as the components contained therein can be similarly used in all adhesive compositions other than the three adhesive compositions (in the present specification, these are referred to as "adhesive compositions other than the adhesive compositions (I-1) to (I-3)").

Examples of the adhesive compositions other than the adhesive compositions (I-1) to (I-3) include energy ray-curable adhesive compositions and non-energy ray-curable adhesive compositions.

Examples of the non-energy ray-curable adhesive composition include an adhesive composition (I-4) containing a non-energy ray-curable adhesive resin (I-1a) such as an acrylic resin, a urethane resin, a rubber resin, a silicone resin, an epoxy resin, a polyvinyl ether, a polycarbonate, or an ester resin, and a non-energy ray-curable adhesive composition containing an acrylic resin is preferable.

The adhesive compositions other than the adhesive compositions (I-1) to (I-3) preferably contain one or more kinds of crosslinking agents, and the content thereof may be set to the same level as in the case of the adhesive composition (I-1) or the like.

< adhesive composition (I-4) >

A preferable adhesive composition (I-4) includes, for example, an adhesive composition containing the adhesive resin (I-1a) and a crosslinking agent.

[ adhesive resin (I-1a) ]

Examples of the solvent in the adhesive composition (I-3) include the same solvents as those in the adhesive composition (I-1).

The adhesive resin (I-1a) contained in the adhesive composition (I-4) may be one type or two or more types, and when two or more types are used, the combination and ratio thereof may be arbitrarily selected.

In the adhesive composition (I-4), the content of the adhesive resin (I-1a) is preferably 5 to 99% by mass, more preferably 10 to 95% by mass, and particularly preferably 15 to 90% by mass, based on the total mass of the adhesive composition (I-4).

[ crosslinking agent ]

When the acrylic polymer having a structural unit derived from a functional group-containing monomer in addition to a structural unit derived from an alkyl (meth) acrylate is used as the adhesive resin (I-1a), it is preferable that the adhesive composition (I-4) further contains a crosslinking agent.

The crosslinking agent in the adhesive composition (I-4) may be the same crosslinking agent as that in the adhesive composition (I-1).

The crosslinking agent contained in the adhesive composition (I-4) may be one kind only, or two or more kinds, and in the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

The content of the crosslinking agent in the adhesive composition (I-4) is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.3 to 15 parts by mass, relative to 100 parts by mass of the content of the adhesive resin (I-1 a).

[ other additives ]

The adhesive composition (I-4) may further contain other additives not belonging to any of the above-mentioned components within a range not impairing the effects of the present invention.

Examples of the other additives include the same other additives as those in the adhesive composition (I-1).

The adhesive composition (I-4) may contain only one other additive, or may contain two or more other additives, and when two or more other additives are contained, the combination and ratio of these additives may be arbitrarily selected.

The content of the other additives in the adhesive composition (I-4) is not particularly limited, and may be appropriately selected depending on the kind thereof.

[ solvent ]

The adhesive composition (I-4) may also contain a solvent for the same purpose as in the case of the adhesive composition (I-1).

The solvent in the adhesive composition (I-4) may be the same solvent as that in the adhesive composition (I-1).

The adhesive composition (I-4) may contain only one solvent, or may contain two or more solvents, and when two or more solvents are contained, the combination and ratio of the solvents can be arbitrarily selected.

The content of the solvent in the adhesive composition (I-4) is not particularly limited, and may be appropriately adjusted.

Preparation method of adhesive composition

The adhesive compositions other than the adhesive compositions (I-1) to (I-3), such as the adhesive compositions (I-1) to (I-3) and the adhesive composition (I-4), can be obtained by blending the components for constituting the adhesive compositions, that is, the adhesive and, if necessary, the components other than the adhesive.

The order of addition of the components in blending is not particularly limited, and two or more components may be added simultaneously.

When a solvent is used, the solvent may be used by mixing any of the blend components other than the solvent and pre-diluting the blend components, or the solvent may be used by mixing the solvent with any of the blend components other than the solvent without pre-diluting the blend components.

The method for mixing the components at the time of blending is not particularly limited, and may be appropriately selected from the following known methods: a method of mixing by rotating a stirrer, a stirring blade, or the like; a method of mixing using a mixer (mixer); a method of mixing by applying ultrasonic waves, and the like.

The temperature and time when the components are added and mixed are not particularly limited as long as the components are not deteriorated, and may be appropriately adjusted, but the temperature is preferably 15 to 30 ℃.

○ film for forming thermosetting protective film

The thermosetting protective film-forming film is thermosetting, and it is finally cured to give a protective film having high impact resistance. The protective film prevents, for example, the occurrence of cracks in the semiconductor chip after the dicing step.

The protective film-forming film can be formed from a thermosetting protective film-forming composition described later.

The thermosetting protective film-forming film may be composed of only one layer (single layer) or may be composed of a plurality of layers of two or more layers, and in the case of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited.

The thickness of the film for forming a thermosetting protective film is not particularly limited, but is preferably 1 to 100 μm, more preferably 5 to 75 μm, and particularly preferably 5 to 50 μm. When the thickness of the thermosetting protective film-forming film is not less than the lower limit value, the adhesive strength to the semiconductor wafer and the semiconductor chip as the adherend becomes higher. Further, by setting the thickness of the film for forming a thermosetting protective film to the upper limit value or less, the protective film as a cured product can be cut more easily by a shear force when picking up a semiconductor chip.

Examples of a preferable thermosetting protective film-forming film include a thermosetting protective film-forming film containing a polymer component (a) and a thermosetting component (B). The polymer component (a) is a component formed by polymerization reaction of a polymerizable compound. The thermosetting component (B) is a component obtained by performing a curing (polymerization) reaction using heat as a reaction inducing agent. In the present invention, the polymerization reaction also includes a polycondensation reaction. Hereinafter, the "thermosetting protective film-forming film" is also simply referred to as "protective film-forming film".

In the present invention, the protective film obtained by curing the protective film-forming film has an adhesive force between the protective film and the support sheet of preferably 50 to 1500mN/25mm, more preferably 52 to 1450mN/25mm, and particularly preferably 53 to 1430mN/25 mm. When the adhesive force is not less than the lower limit value, picking up of the semiconductor chip with the protective film other than the target semiconductor chip can be suppressed when the semiconductor chip with the protective film is picked up, and the target semiconductor chip with the protective film can be picked up with high selectivity. Further, by setting the above-mentioned adhesion to the upper limit or less, when the semiconductor chip with the protective film is picked up, the breakage and chipping of the semiconductor chip can be suppressed. Thus, by making the adhesion within a specific range, the composite sheet for forming a protective film has good pickup adaptability.

The adhesion between the protective film and the support sheet was measured by the following method.

That is, a composite sheet for forming a protective film having a width of 25mm and an arbitrary length is attached to an adherend through a film for forming a protective film.

Next, the protective film-forming film was heat-cured to form a protective film, and then the support sheet was peeled from the protective film attached to the adherend at a peeling speed of 300 mm/min. The peeling at this time is so-called 180 ° peeling, in which the support sheet is peeled in the longitudinal direction thereof (the longitudinal direction of the composite sheet for forming a protective film) so that the surfaces of the protective film and the support sheet which are in contact with each other are at an angle of 180 ° to each other. Then, the load (peel force) at the time of 180 ° peel was measured, and the measurement value was taken as the above-mentioned adhesive force (mN/25 mm).

The length of the protective film-forming composite sheet to be measured is not particularly limited as long as it is within a range in which the adhesive force can be stably detected, but is preferably 100 to 300 mm. In the measurement, it is preferable to stabilize the state of attachment of the composite sheet for forming a protective film while the composite sheet for forming a protective film is in the state of being attached to an adherend.

In the present invention, the adhesive force between the protective film-forming film and the supporting sheet is not particularly limited, and may be, for example, 80mN/25mm or more, but is preferably 100mN/25mm or more, more preferably 150mN/25mm or more, and particularly preferably 200mN/25mm or more. By setting the above-mentioned adhesive force to 100mN/25mm or more, peeling of the film for forming a protective film from the supporting sheet at the time of dicing can be suppressed, and for example, a semiconductor chip having the film for forming a protective film on the back surface can be suppressed from flying off the supporting sheet.

On the other hand, the upper limit of the adhesion between the protective film-forming film and the support sheet is not particularly limited. For example, the concentration may be 4000mN/25mm, 3500mN/25mm, 3000mN/25mm, or the like. These values are but one example.

The adhesive force between the protective film-forming film and the support sheet is preferably 80mN/25mm or more and 4000mN/25mm or less, more preferably 100mN/25mm or more and 4000mN/25mm or less, still more preferably 150mN/25mm or more and 3500mN/25mm or less, and particularly preferably 200mN/25mm or more and 3000mN/25mm or less.

The adhesive force between the protective film-forming film and the support sheet can be measured by the same method as the above-described adhesive force between the protective film and the support sheet, except that the curing by heating of the protective film-forming film for measurement is not performed.

The above-mentioned adhesion between the protective film and the support sheet and the adhesion between the protective film-forming film and the support sheet can be adjusted by, for example, adjusting the kind and amount of the component contained in the protective film-forming film, the material constituting the layer in which the protective film-forming film is provided in the support sheet, and the surface state of the layer.

For example, the kind and amount of the components contained in the protective film-forming composition can be adjusted by the kind and amount of the components contained in the protective film-forming composition described later. Further, the adhesion between the protective film or the protective film-forming film and the support sheet can be more easily adjusted by adjusting, for example, the type and content of the polymer, the content of the filler (D), or the content of the crosslinking agent (F) in the components contained in the protective film-forming composition.

In addition, for example, when the layer in which the protective film-forming film is provided in the support sheet is an adhesive agent layer, the constituent material thereof can be appropriately adjusted by adjusting the kind and amount of the component contained in the adhesive agent layer. The kind and amount of the component contained in the adhesive layer can be adjusted by the kind and amount of the component contained in the adhesive composition.

On the other hand, when the layer of the support sheet on which the protective film-forming film is provided is a base material, the adhesion of the protective film or the protective film-forming film to the support sheet can be adjusted not only by the material constituting the base material but also by the surface state of the base material. The surface state of the base material can be subjected to, for example, the surface treatment such as sandblasting or solvent treatment to improve the adhesion between the base material and another layer; oxidation treatment such as corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone-ultraviolet irradiation treatment, flame treatment, chromic acid treatment, and hot air treatment; any one of undercoating treatment and the like.

The protective film-forming film may be thermosetting and energy-ray-curable, and may contain, for example, an energy-ray-curable component (a) as one side.

The energy ray-curable component (a) is preferably uncured, preferably adhesive, and more preferably uncured and adhesive.

Examples of the energy ray-curable component (a) include an energy ray-curable adhesive resin in which an unsaturated group is introduced into a side chain of a non-energy ray-curable adhesive resin; a monomer or oligomer having an energy ray-polymerizable unsaturated group and curable by irradiation with an energy ray, and the like.

The protective film-forming film may be composed of only one layer (single layer) or may be composed of a plurality of layers of two or more layers, and in the case of a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited.

The thickness of the protective film-forming film is preferably 1 to 100 μm, more preferably 5 to 75 μm, and particularly preferably 5 to 50 μm. When the thickness of the protective film forming film is not less than the lower limit value, a protective film having higher protective ability can be formed. Further, by setting the thickness of the protective film forming film to the upper limit value or less, it is possible to suppress the film from becoming excessively thick.

Here, the "thickness of the protective film-forming film" refers to the thickness of the entire protective film-forming film. For example, the thickness of the protective film forming film composed of a plurality of layers means the total thickness of all the layers constituting the protective film forming film.

The curing conditions for forming the protective film by curing the protective film-forming film are not particularly limited as long as the protective film has a degree of curing sufficient to exert its function, and may be appropriately selected depending on the type of the protective film-forming film.

For example, the heating temperature and the heating time for curing the protective film-forming film are preferably 50 to 150 ℃ and 20 minutes to 3 hours, respectively.

When the protective film-forming film is thermosetting and has energy ray curability, the illuminance of the energy ray is preferably 4 to 280mW/cm². The amount of the energy ray during curing is preferably 3 to 1000mJ/cm²。

Composition for Forming thermosetting protective film

The thermosetting protective film-forming composition can be a thermosetting protective film-forming composition containing the constituent material. For example, a thermosetting protective film-forming composition is applied to a surface to be formed of a thermosetting protective film-forming film and dried as necessary, whereby the thermosetting protective film-forming film can be formed at a target site. The content ratio of the components that do not vaporize at ordinary temperature in the composition for forming a thermosetting protective film is generally the same as the content ratio of the components of the film for forming a thermosetting protective film. Here, "normal temperature" is the same as described above.

The thermosetting protective film-forming composition can be applied, for example, by the same method as that used for the application of the adhesive composition described above.

The drying conditions of the thermosetting protective film-forming composition are not particularly limited, but when the thermosetting protective film-forming composition contains a solvent described later, it is preferable to perform heat drying, and in this case, for example, drying is performed at 70 to 130 ℃ for 10 seconds to 5 minutes.

< composition (III-1) for Forming protective film

Examples of the thermosetting protective film-forming composition include a thermosetting protective film-forming composition (III-1) containing a polymer component (a) and a thermosetting component (B) (in the present specification, these may be simply referred to as "protective film-forming composition (III-1)").

[ Polymer component (A) ]

The polymer component (a) is a polymer compound for imparting film formability, flexibility, and the like to the thermosetting protective film.

The polymer component (a) contained in the composition for forming a protective film (III-1) and the film for forming a thermosetting protective film may be one type or two or more types, and when two or more types are used, the combination and ratio thereof may be arbitrarily selected.

Examples of the polymer component (a) include acrylic resins (e.g., resins having a (meth) acryloyl group), polyesters, urethane resins (e.g., resins having a urethane bond), acrylic urethane resins, silicone resins (e.g., resins having a siloxane bond), rubber resins (e.g., resins having a rubber structure), phenoxy resins, thermosetting polyimides, and the like, and acrylic resins are preferable.

As the acrylic resin in the polymer component (a), a known acrylic polymer can be mentioned.

The weight average molecular weight (Mw) of the acrylic resin is preferably 10000 to 2000000, more preferably 100000 to 1500000. By setting the weight average molecular weight of the acrylic resin to be not less than the lower limit, the shape stability (stability with time during storage) of the film for forming a thermosetting protective film is improved. Further, by setting the weight average molecular weight of the acrylic resin to be not more than the upper limit value, the film for forming a thermosetting protective film can easily follow the uneven surface of the adherend, and generation of voids and the like between the adherend and the film for forming a thermosetting protective film can be further suppressed.

In the present specification, unless otherwise specified, the weight average molecular weight means a polystyrene equivalent value measured by a Gel Permeation Chromatography (GPC) method.

The glass transition temperature (Tg) of the acrylic resin is preferably-60 to 70 ℃, more preferably-30 to 50 ℃. When the Tg of the acrylic resin is not less than the lower limit, the adhesive strength between the protective film and the support sheet can be suppressed, and the releasability of the support sheet can be improved. Further, by setting Tg of the acrylic resin to the upper limit value or less, the adhesive strength of the thermosetting protective film-forming film and the protective film to the adherend is improved.

Examples of the acrylic resin include polymers of 1 or 2 or more kinds of (meth) acrylic acid esters; and copolymers of 2 or more monomers selected from (meth) acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.

Examples of the (meth) acrylic ester constituting the acrylic resin include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (also referred to as lauryl (meth) acrylate), tridecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, And alkyl (meth) acrylates having a chain structure in which the alkyl group constituting the alkyl ester has 1 to 18 carbon atoms, such as tetradecyl (meth) acrylate (also referred to as myristyl (meth) acrylate), pentadecyl (meth) acrylate, hexadecyl (meth) acrylate (also referred to as palmityl (meth) acrylate), heptadecyl (meth) acrylate, and octadecyl (meth) acrylate (also referred to as stearyl (meth) acrylate).

Cycloalkyl (meth) acrylates such as isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate;

aralkyl (meth) acrylates such as benzyl (meth) acrylate;

cycloalkenyl (meth) acrylates such as dicyclopentenyl (meth) acrylate;

cycloalkenyloxyalkyl (meth) acrylates such as dicyclopentenyloxyethyl (meth) acrylate, and the like.

(meth) acrylic acid imide;

glycidyl group-containing (meth) acrylates such as glycidyl (meth) acrylate;

hydroxyl group-containing (meth) acrylates such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate;

and substituted amino group-containing (meth) acrylates such as N-methylaminoethyl (meth) acrylate. Here, the "substituted amino group" refers to a group in which one or two hydrogen atoms of an amino group are substituted with a group other than a hydrogen atom.

The acrylic resin may be copolymerized with 1 or 2 or more monomers selected from (meth) acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylol acrylamide, and the like, for example, in addition to the (meth) acrylate.

The acrylic resin may be composed of only one monomer, or two or more monomers. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The acrylic resin may have a functional group which can bond to another compound, such as a vinyl group, (meth) acryloyl group, amino group, hydroxyl group, carboxyl group, or isocyanate group. The functional group of the acrylic resin may be bonded to another compound through a crosslinking agent (F) described later, or may be directly bonded to another compound without the crosslinking agent (F). By allowing the acrylic resin to react with another compound via the functional group, the reliability of the package obtained using the composite sheet for forming a protective film tends to be improved.

In the present invention, as the polymer component (a), a thermoplastic resin other than the acrylic resin (hereinafter, this may be simply referred to as "thermoplastic resin") and an acrylic resin may be used together.

By using the thermoplastic resin, the releasability of the protective film from the support sheet is improved, or the film for forming a thermosetting protective film can easily follow the uneven surface of the adherend, and generation of voids and the like between the adherend and the film for forming a thermosetting protective film can be suppressed.

The weight average molecular weight of the thermoplastic resin is preferably 1000 to 100000, and more preferably 3000 to 80000.

The glass transition temperature (Tg) of the thermoplastic resin is preferably-30 to 150 ℃, and more preferably-20 to 120 ℃.

Examples of the thermoplastic resin include polyester, polyurethane, phenoxy resin, polybutylene, polybutadiene, and polystyrene.

The thermoplastic resin contained in the composition (III-1) for forming a protective film and the thermosetting film for forming a protective film may be one type or two or more types, and when two or more types are used, the combination and ratio thereof may be arbitrarily selected.

In the protective film-forming composition (III-1), regardless of the type of the polymer component (a), the proportion of the content of the polymer component (a) to the total content (total mass) of all the components except the solvent (i.e., the content of the polymer component (a) to the total mass of the thermosetting protective film-forming film) is preferably 5 to 50 mass%, more preferably 10 to 40 mass%, and particularly preferably 15 to 35 mass%.

The polymer component (a) may correspond to the thermosetting component (B). In the present invention, when the protective film-forming composition (III-1) contains such components corresponding to both the polymer component (A) and the thermosetting component (B), the protective film-forming composition (III-1) is considered to contain the polymer component (A) and the thermosetting component (B).

[ thermosetting component (B) ]

The thermosetting component (B) is a component for curing the film for forming a thermosetting protective film to form a hard protective film.

The thermosetting component (B) contained in the composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof may be arbitrarily selected.

Examples of the thermosetting component (B) include epoxy thermosetting resins, thermosetting polyimides, polyurethanes, unsaturated polyesters, silicone resins, etc., and epoxy thermosetting resins are preferred.

(epoxy thermosetting resin)

The epoxy thermosetting resin is composed of an epoxy resin (B1) and a thermosetting agent (B2).

The epoxy thermosetting resin contained in the composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may be one type or two or more types, and when two or more types are used, the combination and ratio thereof may be arbitrarily selected.

Epoxy resin (B1)

Examples of the epoxy resin (B1) include known epoxy resins, and examples thereof include polyfunctional epoxy resins, biphenyl compounds, bisphenol a diglycidyl ether and hydrogenated products thereof, o-cresol novolac epoxy resins, dicyclopentadiene epoxy resins, biphenyl epoxy resins, bisphenol a epoxy resins, bisphenol F epoxy resins, and epoxy resins having a phenylene skeleton.

As the epoxy resin (B1), an epoxy resin having an unsaturated hydrocarbon group can also be used. The compatibility of the epoxy resin having an unsaturated hydrocarbon group with the acrylic resin is higher than that of the epoxy resin having no unsaturated hydrocarbon group with the acrylic resin. Therefore, by using the epoxy resin having an unsaturated hydrocarbon group, the reliability of the package obtained by using the composite sheet for forming a protective film is improved.

Examples of the epoxy resin having an unsaturated hydrocarbon group include compounds obtained by converting a part of epoxy groups of a polyfunctional epoxy resin into a group having an unsaturated hydrocarbon group. Such a compound can be obtained, for example, by addition reaction of (meth) acrylic acid or a derivative thereof with an epoxy group.

Examples of the epoxy resin having an unsaturated hydrocarbon group include compounds in which a group having an unsaturated hydrocarbon group is directly bonded to an aromatic ring or the like constituting the epoxy resin.

The unsaturated hydrocarbon group is a polymerizable unsaturated group, and specific examples thereof include an ethylene group (also referred to as a vinyl group), a 2-propenyl group (also referred to as an allyl group), (meth) acryloyl group, and (meth) acrylamide group, and an acryloyl group is preferable.

In the present specification, the term "derivative" refers to a compound in which at least 1 hydrogen atom of the original compound is substituted with a group (substituent) other than a hydrogen atom.

The number average molecular weight of the epoxy resin (B1) is not particularly limited, but is preferably 300 to 30000, more preferably 300 to 10000, and particularly preferably 300 to 3000, in view of curability of the thermosetting protective film-forming film and strength and heat resistance of the protective film after curing.

In the present specification, unless otherwise specified, "number average molecular weight" refers to a number average molecular weight expressed in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

The epoxy equivalent of the epoxy resin (B1) is preferably 100 to 1100g/eq, more preferably 150 to 1000 g/eq.

In the present specification, "epoxy equivalent" means the number of grams (g/eq) of an epoxy compound containing 1 equivalent of an epoxy group, which can be measured according to the method of JISK7236: 2001.

The epoxy resin (B1) may be used alone or in combination of two or more, and when two or more are used simultaneously, the combination and ratio thereof may be arbitrarily selected.

Heat-curing agent (B2)

The thermosetting agent (B2) functions as a curing agent for the epoxy resin (B1).

Examples of the thermosetting agent (B2) include compounds having two or more functional groups reactive with epoxy groups in one molecule. Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amino group, a carboxyl group, and a group formed by acid anhydride formation of an acid group, and the like, and a phenolic hydroxyl group, an amino group, or a group formed by acid anhydride formation of an acid group is preferable, and a phenolic hydroxyl group or an amino group is more preferable.

Examples of the phenol curing agent having a phenolic hydroxyl group in the thermal curing agent (B2) include polyfunctional phenol resins, biphenol, novolak-type phenol resins, dicyclopentadiene-type phenol resins, and aralkyl phenol resins.

Examples of the amine-based curing agent having an amino group in the thermosetting agent (B2) include dicyandiamide (hereinafter, this may be abbreviated as "DICY").

The thermosetting agent (B2) may have an unsaturated hydrocarbon group.

Examples of the unsaturated hydrocarbon group-containing thermosetting agent (B2) include a compound in which a part of the hydroxyl groups of the phenol resin is substituted with an unsaturated hydrocarbon group-containing group, a compound in which an unsaturated hydrocarbon group-containing group is directly bonded to an aromatic ring of the phenol resin, and the like.

The unsaturated hydrocarbon group in the thermosetting agent (B2) is the same as the unsaturated hydrocarbon group in the above-described epoxy resin having an unsaturated hydrocarbon group.

When a phenol-based curing agent is used as the thermosetting agent (B2), the thermosetting agent (B2) is preferably a thermosetting agent having a high softening point or glass transition temperature in order to improve the peelability of the protective film from the support sheet.

The heat-curing agent (B2) is preferably: a heat curing agent which is in a solid state at normal temperature and does not exhibit curing activity to the epoxy resin (B1), but melts by heating and exhibits curing activity to the epoxy resin (B1) (hereinafter, this may be simply referred to as "heat-active latent epoxy resin curing agent").

The thermally active latent epoxy resin curing agent is stably dispersed in the epoxy resin (B1) in the thermosetting protective film-forming film at normal temperature, but is compatible with the epoxy resin (B1) by heating and reacts with the epoxy resin (B1). By using the thermally active latent epoxy resin curing agent, the storage stability of the composite sheet for forming a protective film can be significantly improved. For example, the curing agent can be prevented from being transferred from the protective film-forming film to the adjacent support sheet, and the thermosetting property of the thermosetting protective film-forming film can be effectively prevented from being lowered. Further, since the thermosetting degree of the film for forming a thermosetting protective film by heating becomes higher, the pick-up property of the semiconductor chip with a protective film described later is further improved.

Examples of the thermally active latent epoxy resin curing agent includeSalts, dibasic acid hydrazides, dicyandiamide, amine adducts of curing agents, and the like.

The number average molecular weight of the resin component such as a polyfunctional phenol resin, a novolak phenol resin, a dicyclopentadiene phenol resin, or an aralkyl phenol resin in the thermosetting agent (B2) is preferably 300 to 30000, more preferably 400 to 10000, and particularly preferably 500 to 3000.

The molecular weight of the non-resin component such as biphenol and dicyandiamide in the thermosetting agent (B2) is not particularly limited, but is preferably 60 to 500, for example.

The heat-curing agent (B2) may be used alone or in combination of two or more, and when two or more are used simultaneously, the combination and ratio thereof may be arbitrarily selected.

The content of the thermosetting agent (B2) in the protective film-forming composition (III-1) and the thermosetting protective film-forming film is preferably 0.1 to 500 parts by mass, more preferably 1 to 200 parts by mass, per 100 parts by mass of the epoxy resin (B1). By setting the content of the thermosetting agent (B2) to the lower limit or more, it becomes easier to cure the thermosetting protective film-forming film. Further, when the content of the thermosetting agent (B2) is not more than the upper limit, the moisture absorption rate of the thermosetting protective film-forming film is reduced, and the reliability of the package obtained by using the composite sheet for forming a protective film is further improved.

In the protective film-forming composition (III-1) and the film for forming a thermosetting protective film, the content of the thermosetting component (B) (for example, the total content of the epoxy resin (B1) and the thermosetting agent (B2)) is preferably 1 to 100 parts by mass, more preferably 1.5 to 85 parts by mass, and particularly preferably 2 to 70 parts by mass, relative to 100 parts by mass of the content of the polymer component (a). When the content of the thermosetting component (B) is in such a range, the adhesive force between the protective film and the support sheet is suppressed, and the releasability of the support sheet is improved.

[ curing Accelerator (C) ]

The composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may further contain a curing accelerator (C). The curing accelerator (C) is a component for adjusting the curing speed of the composition (III-1) for forming a protective film.

Examples of the preferable curing accelerator (C) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris (dimethylaminomethyl) phenol; imidazoles (i.e., imidazoles in which at least one hydrogen atom is replaced with a group other than a hydrogen atom) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4, 5-dimethyloimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organophosphines such as tributylphosphine, diphenylphosphine, and triphenylphosphine (i.e., phosphines in which at least one hydrogen atom is substituted with an organic group); tetraphenylphosphoniumTetraphenylborate salts such as tetraphenylborate and triphenylphosphine tetraphenylborate.

The curing accelerator (C) contained in the composition for forming a protective film (III-1) and the film for forming a thermosetting protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof may be arbitrarily selected.

When the curing accelerator (C) is used, the content of the curing accelerator (C) is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the thermosetting component (B) in the composition (III-1) for forming a protective film and the film for forming a thermosetting protective film. By setting the content of the curing accelerator (C) to the lower limit or more, the effect of using the curing accelerator (C) can be more remarkably obtained. Further, by setting the content of the curing accelerator (C) to the upper limit or less, for example, the effect of suppressing the occurrence of segregation due to the highly polar curing accelerator (C) moving to the side of the adhesive interface with the adherend in the film for forming a thermosetting protective film under high temperature-high humidity conditions is increased, and the reliability of the package obtained by using the composite sheet for forming a protective film is further improved.

[ Filler (D) ]

The composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may further contain a filler (D). By incorporating the filler (D) into the thermosetting protective film-forming film, it becomes easy to adjust the thermal expansion coefficient of the protective film obtained by curing the thermosetting protective film-forming film, and by optimizing the thermal expansion coefficient with respect to the object to be protected, the reliability of the package obtained by using the composite sheet for protecting film formation is further improved. Further, by incorporating the filler (D) into the thermosetting protective film-forming film, the moisture absorption rate of the protective film can be reduced, and the heat dissipation can be improved.

The filler (D) may be any of an organic filler and an inorganic filler, and is preferably an inorganic filler.

Examples of preferable inorganic fillers include powders of silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, boron nitride, and the like; beads obtained by spheroidizing these inorganic fillers; surface modifications of these inorganic filler materials; single crystal fibers of these inorganic filler materials; glass fibers, and the like.

Among them, the inorganic filler is preferably silica or alumina.

The filler (D) contained in the composition (III-1) for forming a protective film and the thermosetting film for forming a protective film may be one type or two or more types, and when two or more types are used, the combination and ratio thereof may be arbitrarily selected.

When the filler (D) is used, the content of the filler (D) in the protective film-forming composition (III-1) is preferably 5 to 80% by mass, more preferably 7 to 60% by mass, based on the total content of all the components except the solvent (the total mass of the protective film-forming composition (III-1)). By making the content of the filler (D) in such a range, it becomes easier to adjust the above-mentioned thermal expansion coefficient.

[ coupling agent (E) ]

The composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may further contain a coupling agent (E). By using a compound having a functional group reactive with an inorganic compound or an organic compound as the coupling agent (E), the adhesiveness and adherence of the thermosetting protective film-forming film to an adherend can be improved. Further, by using the coupling agent (E), the protective film obtained by curing the thermosetting protective film-forming film does not deteriorate heat resistance, and water resistance is improved.

The coupling agent (E) is preferably a compound having a functional group reactive with the functional group of the polymer component (a), the thermosetting component (B), or the like, and more preferably a silane coupling agent.

Examples of the preferable silane coupling agent include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxymethyldiethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, 3- (2-aminoethylamino) propylmethyldiethoxysilane, 3- (phenylamino) propyltrimethoxysilane, 3-anilinopropyltrimethoxysilane, 3-ureopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, and the like, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis (3-triethoxysilylpropyl) tetrasulfide, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, imidazolesilane and the like.

The coupling agent (E) contained in the composition for forming a protective film (III-1) and the film for forming a thermosetting protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof may be arbitrarily selected.

When the coupling agent (E) is used, the content of the coupling agent (E) is preferably 0.03 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the total content of the polymer component (A) and the thermosetting component (B) in the composition (III-1) for forming a protective film and the film for forming a thermosetting protective film. By setting the content of the coupling agent (E) to the lower limit or more, effects produced by using the coupling agent (E) such as improvement of dispersibility of the filler (D) in the resin, improvement of adhesion between the thermosetting protective film-forming film and the adherend, and the like can be more remarkably obtained. Further, by setting the content of the coupling agent (E) to the upper limit value or less, the occurrence of degassing can be further suppressed.

[ crosslinking agent (F) ]

When the acrylic resin or other compound having a functional group such as a vinyl group, (meth) acryloyl group, amino group, hydroxyl group, carboxyl group, or isocyanate group, which is capable of bonding to another compound, is used as the polymer component (a), the protective film-forming composition (III-1) and the thermosetting protective film-forming film may further contain a crosslinking agent (F) for bonding the functional group to another compound and crosslinking the functional group. By crosslinking with the crosslinking agent (F), the initial adhesive force and cohesive force of the film for forming a thermosetting protective film can be adjusted.

Examples of the crosslinking agent (F) include an organic polyisocyanate compound, an organic polyimine compound, a metal chelate crosslinking agent (i.e., a crosslinking agent having a metal chelate structure), an aziridine crosslinking agent (i.e., a crosslinking agent having an aziridine group), and the like.

Examples of the organic polyisocyanate compound include an aromatic polyisocyanate compound, an aliphatic polyisocyanate compound, and an alicyclic polyisocyanate compound (hereinafter, these compounds may be collectively abbreviated as "aromatic polyisocyanate compound, etc.); trimers, isocyanurate bodies and adducts of the aromatic polyisocyanate compounds and the like; and isocyanate-terminated urethane prepolymers obtained by reacting the aromatic polyisocyanate compound and the like with a polyol compound. The "adduct" refers to a reaction product of the aromatic polyisocyanate compound, the aliphatic polyisocyanate compound or the alicyclic polyisocyanate compound with a low molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane or castor oil, and examples of the adduct include xylylene diisocyanate adducts of trimethylolpropane described later and the like. Further, the "isocyanate-terminated urethane prepolymer" refers to a prepolymer having a urethane bond and having an isocyanate group at a terminal portion of a molecule.

More specific examples of the organic polyisocyanate compound include 2, 4-tolylene diisocyanate; 2, 6-toluene diisocyanate; 1, 3-xylylene diisocyanate; 1, 4-xylene diisocyanate; diphenylmethane-4, 4' -diisocyanate; diphenylmethane-2, 4' -diisocyanate; 3-methyl diphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; dicyclohexylmethane-4, 4' -diisocyanate; dicyclohexylmethane-2, 4' -diisocyanate; a compound obtained by adding one or more of tolylene diisocyanate, hexamethylene diisocyanate and xylylene diisocyanate to all or a part of hydroxyl groups of a polyol such as trimethylolpropane; lysine diisocyanate, and the like.

Examples of the organic polyimine compound include N, N ' -diphenylmethane-4, 4 ' -bis (1-aziridinecarboxamide), trimethylolpropane-tris- β -aziridinylpropionate, tetramethylolmethane-tris- β -aziridinylpropionate, and N, N ' -toluene-2, 4-bis (1-aziridinecarboxamide) triethylenemelamine.

When an organic polyisocyanate compound is used as the crosslinking agent (F), a hydroxyl group-containing polymer is preferably used as the polymer component (A). When the crosslinking agent (F) has an isocyanate group and the polymer component (a) has a hydroxyl group, the crosslinked structure can be easily introduced into the film for forming a thermosetting protective film by the reaction of the crosslinking agent (F) with the polymer component (a).

The crosslinking agent (F) contained in the composition for forming a protective film (III-1) and the film for forming a thermosetting protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof may be arbitrarily selected.

When the crosslinking agent (F) is used, the content of the crosslinking agent (F) in the protective film forming composition (III-1) is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and particularly preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the content of the polymer component (A). By making the content of the crosslinking agent (F) the lower limit or more, the effect produced by using the crosslinking agent (F) can be more remarkably obtained. When the content of the crosslinking agent (F) is not more than the upper limit, it is possible to suppress an excessive decrease in the adhesive strength between the thermosetting protective film-forming film and the support sheet and between the thermosetting protective film-forming film and the semiconductor wafer or the semiconductor chip.

In the present invention, the effects of the present invention can be sufficiently obtained without using the crosslinking agent (F).

[ energy ray-curable resin (G) ]

The protective film-forming composition (III-1) may further contain an energy ray-curable resin (G). By incorporating the energy ray-curable resin (G) into the film for forming a thermosetting protective film, the properties can be changed by irradiation with an energy ray.

The energy ray-curable resin (G) is obtained by polymerizing (curing) an energy ray-curable compound.

Examples of the energy ray-curable compound include compounds having at least one polymerizable double bond in the molecule, and acrylate compounds having a (meth) acryloyl group are preferable.

Examples of the acrylic ester-based compound include (meth) acrylates having a chain-like aliphatic skeleton such as trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 4-butanediol di (meth) acrylate, and 1, 6-hexanediol di (meth) acrylate; cyclic aliphatic skeleton-containing (meth) acrylates such as dicyclopentyl di (meth) acrylate; polyalkylene glycol (meth) acrylates such as polyethylene glycol di (meth) acrylate; an oligoester (meth) acrylate; a urethane (meth) acrylate oligomer; epoxy-modified (meth) acrylates; a polyether (meth) acrylate other than the polyalkylene glycol (meth) acrylate; itaconic acid oligomers, and the like.

The weight average molecular weight of the energy ray-curable compound is preferably 100 to 30000, more preferably 300 to 10000.

The energy ray-curable compound used for polymerization may be only one kind, or two or more kinds. When two or more kinds are used, the combination and ratio thereof can be arbitrarily selected.

The energy ray-curable resin (G) contained in the protective film-forming composition (III-1) may be one type only, or two or more types, and when two or more types are used, the combination and ratio thereof may be arbitrarily selected.

In the composition (III-1) for forming a protective film, the content of the energy ray-curable resin (G) is preferably 1 to 95% by mass, more preferably 2 to 90% by mass, and particularly preferably 3 to 85% by mass, based on the total mass of the composition (III-1) for forming a protective film.

[ photopolymerization initiator (H) ]

When the protective film-forming composition (III-1) contains the energy ray-curable resin (G), a photopolymerization initiator (H) may be contained in order to efficiently perform the polymerization reaction of the energy ray-curable resin (G).

The photopolymerization initiator (H) in the protective film-forming composition (III-1) may be the same photopolymerization initiator as that in the adhesive composition (I-1).

The photopolymerization initiator (H) contained in the protective film-forming composition (III-1) may be one kind only, or two or more kinds, and in the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

In the protective film-forming composition (III-1), the content of the photopolymerization initiator (H) is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, and particularly preferably 2 to 5 parts by mass, relative to 100 parts by mass of the content of the energy ray-curable resin (G).

[ colorant (I) ]

The composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may further contain a colorant (I).

Examples of the colorant (I) include known colorants such as inorganic pigments, organic pigments, and organic dyes.

Examples of the organic pigment and the organic dye include amines(aminium) type pigment, cyanine type pigment, merocyanine type pigment, croconic acid (croconium) type pigment, squarylium (squarylium) type pigment, chamomile blue(azulenium) pigments, polymethine pigments, naphthoquinone pigments, pyransExamples of the colorant include pigments such as phthalocyanine-based pigments, naphthalocyanine-based pigments, naphthalimide-based pigments, azo-based pigments, condensed azo-based pigments, indigo-based pigments, perinone-based pigments, perylene-based pigments, dioxazine-based pigments, quinacridone-based pigments, isoindolinone-based pigments, quinophthalone-based pigments, and the likePyrrole pigments, thioindigo pigments, metal complex pigments (metal complex salt dyes), dithiol metal complex pigments, indophenol pigments, triarylmethane pigments, anthraquinone pigments, dioxazine pigments, naphthol pigments, azomethine pigments, benzimidazolone pigments, pyranthrone pigments, threne pigments, and the like.

Examples of the inorganic pigments include carbon black, cobalt pigments, iron pigments, chromium pigments, titanium pigments, vanadium pigments, zirconium pigments, molybdenum pigments, ruthenium pigments, platinum pigments, ITO (indium tin oxide) pigments, ATO (antimony tin oxide) pigments, and the like.

The colorant (I) contained in the composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof may be arbitrarily selected.

When the colorant (I) is used, the content of the colorant (I) in the film for forming a thermosetting protective film may be appropriately adjusted depending on the purpose. For example, printing may be performed on the protective film by laser irradiation, and printing visibility may be adjusted by adjusting the content of the colorant (I) in the thermosetting protective film-forming film and adjusting the light transmittance of the protective film. Further, by adjusting the content of the colorant (I) in the film for forming a thermosetting protective film, the design of the protective film can be improved, or the polishing trace on the back surface of the semiconductor wafer can be made less visible. In view of these points, the ratio of the content of the colorant (I) to the total content of all components except the solvent in the composition (III-1) for forming a protective film (i.e., the content of the colorant (I) in the film for forming a thermosetting protective film) is preferably 0.1 to 10% by mass, more preferably 0.1 to 7.5% by mass, and particularly preferably 0.1 to 5% by mass. By making the content of the colorant (I) the lower limit or more, the effect produced by using the colorant (I) can be more remarkably obtained. Further, by setting the content of the colorant (I) to the upper limit or less, excessive decrease in light transmittance of the film for forming a thermosetting protective film can be suppressed.

[ general additive (J) ]

The composition (III-1) for forming a protective film and the film for forming a thermosetting protective film may further contain a general-purpose additive (J) within a range not to impair the effects of the present invention.

The general-purpose additive (J) may be a known additive, may be arbitrarily selected according to the purpose, and is not particularly limited, but preferable additives include, for example, a plasticizer, an antistatic agent, an antioxidant, and a gettering agent (gelling agent).

The general additive (I) contained in the composition for forming a protective film (III-1) and the film for forming a thermosetting protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio thereof may be arbitrarily selected.

The content of the general-purpose additive (I) in the protective film-forming composition (III-1) and the thermosetting protective film-forming film is not particularly limited, and may be appropriately selected depending on the purpose.

[ solvent ]

The composition (III-1) for forming a protective film preferably further contains a solvent. The composition (III-1) for forming a protective film containing a solvent is excellent in handling properties.

The solvent is not particularly limited, but preferable examples thereof include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutanol (2-methylpropane-1-ol), and 1-butanol; esters such as ethyl acetate and butyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.

The amount of the solvent contained in the composition (III-1) for forming a protective film may be one kind or two or more kinds, and when two or more kinds are contained, the combination and ratio of these may be arbitrarily selected.

The solvent contained in the composition (III-1) for forming a protective film is preferably methyl ethyl ketone or the like, since the components contained in the composition (III-1) for forming a protective film can be mixed more uniformly.

Preparation method of composition for Forming thermosetting protective film

The composition for forming a thermosetting protective film such as the composition (III-1) for forming a protective film can be obtained by blending the respective components for constituting the composition.

The order of addition of the components in blending is not particularly limited, and two or more components may be added simultaneously.

When a solvent is used, the solvent may be used by mixing with any of the blending components other than the solvent and preliminarily diluting the blending components, or the solvent may be used by mixing with the blending components without preliminarily diluting any of the blending components other than the solvent.

The method of mixing the components at the time of blending is not particularly limited. The method may be appropriately selected from the following known methods: a method of mixing by rotating a stirrer, a stirring blade, or the like; a method of mixing using a mixer; a method of mixing by applying ultrasonic waves, and the like.

The temperature and time when each component is added and mixed are not particularly limited as long as each component is not deteriorated, and the temperature and time may be appropriately adjusted. But the preferred temperature is 15 to 30 ℃.

As a composite sheet which is attached to the back surface of a semiconductor wafer or a semiconductor chip on the opposite side to the circuit surface like the composite sheet for forming a protective film of the present invention and has a layer exhibiting adhesiveness on a supporting sheet, there is a dicing die bonding sheet (dicing sheet).

However, the adhesive layer provided in the die bonding sheet is picked up from the support sheet together with the semiconductor chip, and then functions as an adhesive when the semiconductor chip is attached to a substrate, a lead frame, another semiconductor chip, or the like. On the other hand, the protective film-forming film in the protective film-forming composite sheet of the present invention is the same as the adhesive layer in that it is picked up from the support sheet together with the semiconductor chip, but it finally becomes a protective film by curing, and has a function of protecting the back surface of the semiconductor chip attached. As described above, the protective film forming film of the present invention is different in the purpose of dicing the adhesive layer in the die bonding sheet, and naturally, the required performance is different. Reflecting the difference in the application, the protective film forming film tends to be harder and harder to pick up than the adhesive layer in the ordinary dicing die bonding sheet. Therefore, it is generally difficult to directly transfer the adhesive layer in the cut die bonding sheet to be used as a film for protective film formation in the composite sheet for protective film formation. The protective film-forming composite sheet of the present invention, which is provided with a thermosetting protective film-forming film, is required to have excellent pick-up suitability for semiconductor chips with protective films.

◇ method for manufacturing composite sheet for forming protective film

The composite sheet for forming a protective film of the present invention can be produced by sequentially laminating the above layers so that the layers are in a corresponding positional relationship. The formation method of each layer is the same as that described above.

For example, when an adhesive layer is laminated on a substrate in the production of a support sheet, the adhesive composition may be applied to the substrate and dried as necessary.

On the other hand, for example, when a film for forming a protective film is further laminated on an adhesive layer laminated on a substrate, the film for forming a protective film can be directly formed by applying the composition for forming a protective film on the adhesive layer. In the same manner, a layer other than the film for forming a protective film can be laminated on the adhesive layer using the composition for forming the layer. In this manner, when an arbitrary composition is used to form a laminated structure of two successive layers, a layer formed of the composition can be further coated with the composition to form a new layer.

However, it is preferred that: the composition is used to form a post-laminated layer of the two layers on another release film in advance, and an exposed surface of the formed layer on the side opposite to the side in contact with the release film is bonded to an exposed surface of the other layer formed, thereby forming a continuous two-layer laminated structure. In this case, the composition is preferably applied to the release-treated surface of the release film. After the laminated structure is formed, the release film may be removed as necessary.

For example, in the case of producing a composite sheet for forming a protective film (a composite sheet for forming a protective film in which a support sheet is a laminate of a substrate and an adhesive layer) in which an adhesive layer is laminated on a substrate and a film for forming a protective film is laminated on the adhesive layer, the adhesive layer is laminated on the substrate by applying an adhesive composition to the substrate and drying it as necessary, and the film for forming a protective film is formed on a release film by applying a composition for forming a protective film to the release film and drying it as necessary. Then, the exposed surface of the protective film-forming film is laminated on the exposed surface of the adhesive layer laminated on the base material, whereby a protective film-forming composite sheet can be obtained.

In addition, when the adhesive layer is laminated on the substrate, as described above, the adhesive layer may be laminated on the substrate by applying the adhesive composition on the release film and drying it as necessary to form the adhesive layer on the release film and bonding the exposed surface of the layer to the surface on the one side of the substrate, instead of applying the adhesive composition on the substrate.

In either method, the release film may be removed at any timing after the formation of the target layered structure.

In this manner, since all layers other than the base material constituting the composite sheet for forming a protective film can be laminated by a method of forming the layers on the release film in advance and bonding the layers to the surface of the target layer, the composite sheet for forming a protective film can be produced by appropriately selecting the layers to be used in such steps as necessary.

The composite sheet for forming a protective film is generally stored in a state where a release film is bonded to the surface of the outermost layer (for example, a film for forming a protective film) on the opposite side to the support sheet. Therefore, even when a composition for forming a layer constituting the outermost layer, such as a composition for forming a protective film, is applied to a release film (preferably, a release-treated surface thereof) and dried as necessary to form the layer constituting the outermost layer on the release film, and other layers are laminated on an exposed surface of the layer on the opposite side to the side in contact with the release film by any of the above-described methods, the release film is bonded without being removed, a composite sheet for forming a protective film can be obtained.

◎ method for manufacturing semiconductor chip with protective film

The method for manufacturing a semiconductor chip with a protective film according to the present invention includes: a step of laminating a semiconductor wafer on the thermosetting protective film forming film side of the composite sheet for forming a protective film to produce a laminate;

irradiating the interior of the semiconductor wafer of the laminate with laser light to form a modified layer in the interior of the semiconductor wafer;

a step of heating and curing the film for forming a thermosetting protective film of the laminate to form a protective film; and

and a step of dividing the semiconductor wafer, the thermosetting protective film-forming film, or the protective film by cold-expanding the laminate at a temperature lower than normal temperature.

Further, the manufacturing method may further include: separating and picking up the divided semiconductor wafer from the support sheet together with the protective film laminated on the semiconductor wafer, thereby obtaining semiconductor chips with the protective film.

The method for manufacturing a semiconductor chip with a protective film according to the present invention may include, after the step of laminating a semiconductor wafer on the thermosetting protective film-forming film side of the composite sheet for forming a protective film to form a laminate, the steps of: irradiating the inside of the semiconductor wafer of the laminate with laser light to form a modified layer inside the semiconductor wafer; a step of dividing the semiconductor wafer and the film for forming a thermosetting protective film by cold-expanding the laminate at a temperature lower than normal temperature; and a step of heating and curing the film for forming a thermosetting protective film of the laminate to form a protective film. An example of a method for manufacturing the semiconductor chip with the protective film will be described with reference to fig. 3.

First, the back surface of the semiconductor wafer 18 is ground to a desired thickness, and then the back surface of the semiconductor wafer 18 after back grinding is attached to the thermosetting protective film forming film 23 of the composite sheet for protective film formation 2, and at the same time, the composite sheet for protective film formation 2 is fixed to the ring frame 17 ((a) in fig. 3). When the back grinding tape 20 is attached to the surface (electrode forming surface) of the semiconductor wafer 18, the back grinding tape 20 is removed from the semiconductor wafer 18.

Next, the composite sheet for forming a protective film 2 is irradiated with laser light (SD) so as to be focused at a focal point set in the semiconductor wafer 18, thereby forming a modified layer 18c in the semiconductor wafer 18 ((b) in fig. 3). Here, laser printing is performed by irradiating laser light from the support sheet 10 side as necessary. Next, the semiconductor wafer 18 on which the modified layer is formed and the composite sheet 2 for forming a protective film is attached on the back surface thereof is cold-expanded (CE) together with the composite sheet 2 for forming a protective film in the planar direction of the composite sheet for forming a protective film, thereby cutting the film for forming a curable protective film and at the same time, the semiconductor wafer 18 is divided into individual pieces at the modified layer 18c (fig. 3 (c)). Here, infrared inspection is performed by irradiating infrared laser light from the support sheet 10 side as necessary.

The composite sheet 2 for forming a protective film of the present invention has a loss tangent (tan) at-15 ℃ of the base material 11 of the support sheet 10 of 0.05 or more, and thus the base material 11 has good cold resistance, and the base material 11 of the support sheet 10 is not cracked by Cold Expansion (CE) at a temperature lower than the normal temperature.

Further, the support sheet 10, the singulated film 23 for forming a thermosetting protective film, and the singulated semiconductor chip 19 are laminated and heated to cure the film 23 for forming a thermosetting protective film, thereby forming a protective film 23' (fig. 3 (d)).

The composite sheet 2 for forming a protective film of the present invention has a storage modulus (G') at 80 ℃ of 35.0MPa or more of the base 11 of the support sheet 10, and therefore, even when the thermosetting protective film-forming film 23 is cured by heating, the support sheet 10 is not bent, and even when a plurality of the support sheets 10 are stacked with a minute gap therebetween, and the thermosetting protective film-forming film 23 and the semiconductor chip 19 are individually formed in a stacked state, the thermosetting protective film-forming film 23 is cured by heating, the support sheet 10 can be prevented from coming into contact with another semiconductor chip 19 on the lower side thereof.

Finally, the semiconductor chip 19 is peeled off from the support sheet 10 together with the protective film 23 'attached to the back surface thereof and picked up, thereby obtaining the semiconductor chip 19 with the protective film 23' (fig. 3 (e)). For example, when the support sheet 10 is formed by laminating the base material 11 and the adhesive agent layer 12 is an energy ray-curable layer, the semiconductor chip 19 with the protective film 23 'can be more easily obtained by irradiating an energy ray to cure the adhesive agent layer 12 and picking up the semiconductor chip 19 and the protective film 23' attached to the back surface thereof from the cured adhesive agent layer 12.

In fig. 3, an example of a method for manufacturing a semiconductor chip with a protective film using the composite sheet for forming a protective film 2 having the adhesive layer 16 for a jig is described, and an example of a method for manufacturing a semiconductor chip with a protective film using the composite sheet for forming a protective film 1 not having the adhesive layer 16 for a jig is also the same.

In fig. 3, the modified layer is formed inside the semiconductor wafer 18 by irradiating the composite sheet 2 for forming a protective film with laser light (SD) so as to focus on a focal point set inside the semiconductor wafer 18, but the present invention is not limited to this, and the modified layer forming step, the laminate forming step, the dividing step, and the protective film forming step may be sequentially provided, and specifically, for example, the modified layer may be formed inside the semiconductor wafer 18 to which the back grinding tape 20 is attached, and the composite sheet 2 for forming a protective film may be attached to the semiconductor wafer 18 on which the modified layer is formed. Then, laser printing is performed by irradiating laser light from the support sheet 10 side, and Cold Expansion (CE), hot curing, infrared inspection, and pickup are performed, thereby obtaining the semiconductor chip 19 with the protective film 23'.

The method for manufacturing a semiconductor chip with a protective film according to the present invention may include, after the step of laminating a semiconductor wafer on the thermosetting protective film-forming film side of the composite sheet for forming a protective film to form a laminate, the steps of: a step of heating and curing the film for forming a thermosetting protective film of the laminate to form a protective film; irradiating the inside of the semiconductor wafer with laser light to form a modified layer inside the semiconductor wafer; and a step of dividing the semiconductor wafer and the protective film by cold expanding the laminated body at a temperature lower than a normal temperature. An example of a method for manufacturing the semiconductor chip with the protective film will be described with reference to fig. 4.

First, the back surface of the semiconductor wafer 18 is ground to a desired thickness, and then the back surface of the semiconductor wafer 18 after back grinding is attached to the thermosetting protective film forming film 23 of the composite sheet for protective film formation 2, and at the same time, the composite sheet for protective film formation 2 is fixed to the ring frame 17 ((a) in fig. 4). When the back grinding tape 20 is attached to the surface (electrode forming surface) of the semiconductor wafer 18, the back grinding tape 20 is removed from the semiconductor wafer 18.

Next, the laminated body composed of the support sheet 10, the thermosetting protective film-forming film 23, and the semiconductor wafer 18 is heated to heat and cure the thermosetting protective film-forming film 23, thereby forming the protective film 23' (fig. 4 (b)).

In the composite sheet 2 for forming a protective film of the present invention, the storage modulus (G') of the base material 11 of the support sheet 10 at 80 ℃ is 35.0MPa or more, so that the support sheet 10 is not bent even under the condition that the thermosetting protective film forming film 23 is heat-cured, and the support sheet 10 can be prevented from contacting with another semiconductor wafer 18 on the lower side even when the thermosetting protective film forming film 23 is heat-cured in a state where a plurality of support sheets 10, the thermosetting protective film forming film 23, and the semiconductor wafer 18 are stacked with a minute gap therebetween.

Further, the laser beam (SD) is irradiated from the protective film 23' side so as to be focused on a focal point set in the semiconductor wafer 18, thereby forming a modified layer 18c in the semiconductor wafer 18 ((c) in fig. 4). Here, laser printing is performed by irradiating laser light from the support sheet 10 side as necessary. Next, the semiconductor wafer 18 on which the modified layer 18c is formed and the composite sheet 2 for forming a protective film is attached on the back surface thereof is cold-spread (CE) together with the composite sheet 2 for forming a protective film in the planar direction of the composite sheet for forming a protective film, thereby cutting the protective film 23' and at the same time, the semiconductor wafer 18 is divided and singulated at the modified layer 18c portion ((d) in fig. 4). Here, infrared inspection is performed by irradiating infrared laser light from the support sheet 10 side as necessary.

The composite sheet 2 for forming a protective film of the present invention has a loss tangent (tan) at-15 ℃ of the base material 11 of the support sheet 10 of 0.05 or more, and thus the base material 11 has good cold resistance, and the base material 11 of the support sheet 10 is not cracked by Cold Expansion (CE) at a temperature lower than the normal temperature.

Finally, the semiconductor chip 19 with the protective film 23 'is obtained by peeling and picking up the semiconductor chip 19 from the support sheet 10 together with the protective film 23' attached to the back surface thereof ((e) in fig. 4). For example, when the support sheet 10 is formed by laminating the base material 11 and the adhesive agent layer 12 is an energy ray-curable layer, the adhesive agent layer 12 is cured by irradiation with an energy ray, and the semiconductor chip 19 is picked up together with the protective film 23 'attached to the back surface thereof from the cured adhesive agent layer 12, thereby obtaining the semiconductor chip 19 with the protective film 23'.

In the method for manufacturing a semiconductor chip with a protective film according to the present invention, the order of the respective steps is not limited to the above-described order, and after the heat curing, the support sheet side may be irradiated with laser light to perform laser printing, and then cold spreading (CE) may be performed. The adhesive layer 12 is cured by irradiation with an energy ray as necessary, and then the semiconductor chip 19 with the protective film 23' is picked up.

The method for manufacturing a semiconductor chip with a protective film according to the present invention may include the step of forming the modified layer, the step of forming the laminate, the step of forming the protective film, and the step of dividing in this order, or may include the step of forming the laminate, the step of forming the modified layer, the step of forming the protective film, and the step of dividing in this order.

◎ method for manufacturing semiconductor device

Then, the obtained semiconductor chip with the protective film is flip-chip connected directly to the circuit surface of the substrate in a state where the protective film is attached, by the same method as the conventional method, and then a semiconductor package is manufactured. Then, a target semiconductor device may be manufactured using the semiconductor package.

The composite sheet for forming a protective film of the present invention is a composite sheet for forming a protective film, which comprises:

a support sheet having a base material and an adhesive layer, and a film for forming a thermosetting protective film provided on the support sheet;

the composite sheet for forming a protective film comprises the base material, the adhesive layer, and the film for forming a thermosetting protective film laminated in this order;

the substrate has the following characteristics:

a loss tangent (tan) at-15 ℃ of 0.05 or more, preferably 0.06 or more and 0.09 or less, and

the storage modulus (G') at 80 ℃ is preferably 35.0MPa or more, preferably 60MPa or more and 150MPa or less;

the substrate is characterized in that the substrate is cut into a long side of 110mm × and a short side of 22mm so that the MD direction or the CD direction of the substrate is the long side direction, a load of 2.2g is applied to the substrate so that the measurement pitch before heating is about 100mm, the substrate is heated at 130 ℃ for 2 hours in this state, then the substrate is cooled, and the measurement pitch after heating L is measured at 23 DEG C₁When the temperature of the water is higher than the set temperature,

the thermal expansion and contraction rate X represented by the formula (1) is-3% or more and + 3% or less, preferably 0 to 2.2% when the base material is cut into long sides in the MD direction or in the CD direction;

the base material is preferably a film made of polybutylene terephthalate with a soft component, a three-layer transparent film made of a mixed resin of polypropylene (PP) and an olefin thermoplastic elastomer (TPO), or a three-layer transparent film of Polyethylene (PE)/polypropylene (PP)/Polyethylene (PE);

the adhesive layer is preferably non-energy ray-curable;

the adhesive layer is preferably formed of an adhesive composition containing a (meth) acrylate copolymer (a copolymer obtained by copolymerizing 2-ethylhexyl acrylate, methyl methacrylate, and 2-hydroxyethyl acrylate 10, a bisphenol a-type epoxy resin, and a crosslinking agent;

the protective film-forming film

Preferably, the protective film is formed from a composition for forming a protective film containing a polymer component (preferably, an acrylic polymer obtained by copolymerizing methyl acrylate and 2-hydroxyethyl acrylate), an epoxy resin (preferably, a bisphenol a type epoxy resin and a dicyclopentadiene type epoxy resin), a curing agent (preferably, a heat-activated latent epoxy resin curing agent), an effect promoter (preferably, 2-phenyl-4, 5-dimethyloimidazole), a filler (preferably, a silica filler), a coupling agent (preferably, a silane coupling agent), and a colorant (preferably, a trichromatic mixed pigment).

Further, in the composite sheet for forming a protective film, the thickness of the base material is preferably 15 to 300 μm, preferably 50 to 200 μm, more preferably 60 to 150 μm, and particularly preferably 70 to 100 μm;

the thickness of the adhesive layer is preferably 3 to 20 μm, and more preferably 10 to 15 μm;

the thickness of the protective film-forming film is preferably 1 to 100 μm, more preferably 5 to 75 μm, still more preferably 5 to 50 μm, and particularly preferably 5 to 30 μm.