阅读说明：本技术 耐热脱模片和热压接方法 (Heat-resistant release sheet and thermocompression bonding method ) 是由 秋叶府统 吉松王彦 于 2019-10-01 设计创作，主要内容包括：本申请的耐热脱模片是在利用热加压头进行压接对象物的热压接时配置在压接对象物与热加压头之间而用于防止压接对象物与热加压头的固着的片,其由厚度35μm以下的单层的耐热性树脂薄膜构成,构成耐热性树脂薄膜的耐热性树脂具有310℃以上的熔点和/或210℃以上的玻璃化转变温度。该耐热脱模片的使用温度可以设为例如250℃以上。根据本申请的耐热脱模片,能够更可靠地应对热压接温度上升的要求。(The heat-resistant release sheet is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressure-bonded by the heat pressing head, and is used for preventing the object to be pressure-bonded and the heat pressing head from being fixed, and is composed of a single-layer heat-resistant resin film having a thickness of 35 [ mu ] m or less, wherein the heat-resistant resin constituting the heat-resistant resin film has a melting point of 310 ℃ or higher and/or a glass transition temperature of 210 ℃ or higher. The use temperature of the heat-resistant release sheet may be, for example, 250 ℃. According to the heat-resistant release sheet of the present application, it is possible to more reliably respond to a request for an increase in the thermocompression bonding temperature.)

1. A heat-resistant release sheet which is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressure-bonded by the heat pressing head, and which prevents the object to be pressure-bonded and the heat pressing head from being fixed to each other,

which is composed of a single-layer heat-resistant resin film having a thickness of 35 μm or less,

the heat-resistant resin constituting the heat-resistant resin film has a melting point of 310 ℃ or higher and/or a glass transition temperature of 210 ℃ or higher.

2. The heat-resistant release sheet according to claim 1, wherein the thickness of the heat-resistant resin film is 25 μm or less.

3. The heat-resistant release sheet according to claim 1 or 2, wherein the heat-resistant resin is at least 1 selected from the group consisting of polyimide, polyetherimide, polysulfone, polyethersulfone, aromatic polyether ketone, and polyamideimide.

4. The heat-resistant release sheet according to any one of claims 1 to 3, which has a use temperature of 250 ℃ or higher.

5. The heat-resistant release sheet according to any one of claims 1 to 4, wherein the heat-resistant release sheet has an indentation hardness at 300 ℃ represented by the following formula A₃₀₀(％)＝(d₃₀₀/t₀) X 100 degree of indentation A₃₀₀And is 3 to 15%,

wherein, t₀The thickness of the heat-resistant release sheet at normal temperature, i.e., 20 ℃; d₃₀₀The indentation amount of the penetration probe at 300 ℃ to the heat-resistant release sheet was evaluated by thermomechanical analysis (TMA) based on the following measurement conditions,

the measurement conditions were as follows:

measurement mode: penetration mode and temperature measurement

Shape and tip diameter of the penetrating probe: cylindrical and 1mm phi

Application of pressure: 1MPa of

Temperature increase start temperature and temperature increase rate: 20 ℃ and 10 ℃/min.

6. A heat-resistant release sheet which is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressure-bonded by the heat pressing head, and which prevents the object to be pressure-bonded and the heat pressing head from being fixed to each other,

which is composed of a single-layer heat-resistant resin film having a thickness of 35 μm or less,

the heat-resistant resin constituting the heat-resistant resin film is at least 1 selected from the group consisting of polyimide, polyetherimide, polysulfone, polyethersulfone, aromatic polyether ketone, and polyamideimide.

7. A thermal compression bonding method for bonding an object by a thermal compression head, wherein,

performing thermocompression bonding of the object to be pressure-bonded by the heat pressing head in a state where the heat-resistant release sheet is arranged between the heat pressing head and the object to be pressure-bonded,

the heat-resistant release sheet according to any one of claims 1 to 6.

Technical Field

The present invention relates to a heat-resistant release sheet and a thermal compression bonding method using the same.

Background

Thermocompression bonding is used in the manufacture and flip chip mounting of semiconductor chips and the manufacture of Printed Circuit Boards (PCBs) using an underfill such as NCF (Non-Conductive Film) and NCP (Non-Conductive Paste). The thermocompression bonding method is also used for connection between a PCB and an electronic component using an Anisotropic Conductive Film (ACF). In thermocompression bonding of a bonding object, a thermal pressing head is generally used as a heat source and a pressure source. In order to prevent the fixation between the object to be pressure-bonded and the thermal pressing head during the thermal compression bonding, a heat-resistant release sheet is generally disposed between the object to be pressure-bonded and the thermal pressing head.

Patent document 1 does not disclose the heat-resistant release sheet itself, but discloses a release sheet that is used by being housed in a molding die during molding of a thermosetting resin, and that has a release layer containing a fluorosilicone formed on at least one surface of a thermoplastic resin film.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-201033

Disclosure of Invention

Problems to be solved by the invention

The thermocompression bonding temperature at the time of thermocompression bonding of the object to be bonded is expected to further increase. By further increasing the thermocompression bonding temperature, for example, thermocompression bonding of the object to be bonded in which more layers are stacked than in the past can be achieved, and the manufacturing efficiency and mounting efficiency of the semiconductor chip can be improved. However, the release sheet of patent document 1 is premised on its use at a common molding temperature of a thermosetting resin, i.e., at most about 200 ℃. Patent document 1 does not take into consideration any further increase in the thermocompression bonding temperature that can be expected in the thermocompression bonding by the thermal pressure head in the future. The release sheet of patent document 1 is merely a release sheet used for molding a thermosetting resin, and is not supposed to be used for thermocompression bonding by a hot press head.

The purpose of the present invention is to provide a heat-resistant release sheet that can more reliably meet the demand for a further increase in the thermocompression bonding temperature in thermocompression bonding by a thermocompression head.

Means for solving the problems

The invention provides a heat-resistant release sheet which is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressed by the heat pressing head and is used for preventing the object to be pressure-bonded and the heat pressing head from being fixed,

which is composed of a single-layer heat-resistant resin film having a thickness of 35 μm or less,

the heat-resistant resin constituting the heat-resistant resin film has a melting point of 310 ℃ or higher and/or a glass transition temperature of 210 ℃ or higher.

From other aspects, the present invention provides a thermocompression bonding method,

the hot press bonding method of the object to be bonded by using a hot press head, wherein,

the heat-resistant release sheet is arranged between the heat pressing head and the object to be pressure-bonded, and the object to be pressure-bonded is subjected to thermocompression bonding by the heat pressing head,

the heat-resistant release sheet is the heat-resistant release sheet of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

First, the heat-resistant resin film constituting the heat-resistant release sheet of the present invention has high heat resistance. Secondly, according to the studies of the present inventors, when the release sheet of patent document 1 is used for the thermal compression bonding by the thermal compression head in which the thermal compression bonding temperature is further increased, the object to be compression bonded is contaminated with the decomposition of the release layer on the surface. However, according to the heat-resistant release sheet of the present invention, since the sheet is formed of a single layer of the heat-resistant resin film, contamination of the object to be pressure-bonded can be prevented. Third, when the thermocompression bonding temperature is further increased, particularly when thermocompression bonding is performed on an object to be bonded in which more layers are stacked than in the past, the thermal conductivity of the heat-resistant release sheet disposed between the thermal pressing head and the object to be bonded significantly affects the efficiency of thermocompression bonding. According to the heat-resistant release sheet of the present invention, since the sheet is a single layer and has a thickness of a predetermined thickness or less, good thermal conductivity can be ensured. From these viewpoints, the heat-resistant release sheet of the present invention can more reliably meet the demand for further increase in the thermocompression bonding temperature when thermocompression bonding is performed by the thermal pressing head.

In view of the characteristics of the heat-resistant resin constituting the heat-resistant resin film, the heat-resistant resin film lacks cushioning properties in the thickness direction at a conventional thermocompression bonding temperature, that is, around 200 ℃, and therefore it is difficult to uniformly apply pressure to a bonding object by a heat-pressing head, and therefore, those skilled in the art have considered "it cannot be used as a heat-resistant release sheet for thermocompression bonding by a heat-pressing head" for many years. However, according to the study of the present inventors, it was found that: when the thermocompression bonding temperature is raised to, for example, about 250 ℃, particularly about 300 ℃, the heat-resistant release sheet can be used as a heat-resistant release sheet for thermocompression bonding by a heat pressing head, since the cushioning property in the thickness direction can be unexpectedly secured. The heat-resistant release sheet of the present invention is realized based on findings not yet found by the present inventors based on the above-described various studies.

Drawings

Fig. 1 is a cross-sectional view schematically showing an example of the heat-resistant release sheet of the present invention.

Fig. 2 is a schematic view for explaining an example of a thermal compression bonding method using the heat-resistant release sheet of the present invention.

Fig. 3 is a schematic diagram for explaining a method of evaluating thermal conductivity of a pressure-bonding object when thermocompression bonding is performed using a thermal pressing head with respect to the heat-resistant release sheets of examples and comparative examples.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[ Heat-resistant Release sheet ]

Fig. 1 shows an example of the heat-resistant release sheet of the present invention. The heat-resistant release sheet 1 shown in fig. 1 is composed of a polyimide film 2. The heat-resistant release sheet 1 of fig. 1 has a single-layer structure of a polyimide film 2. The heat-resistant release sheet 1 has high heat resistance derived from polyimide contained in the film 2. The heat-resistant release sheet 1 has a higher heat resistance than a heat-resistant release sheet composed of a thin film of a fluororesin such as Polytetrafluoroethylene (PTFE) or a tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA).

Further, the polyimide film 2 is less likely to be deformed even at high temperatures than a film of, for example, a fluororesin. Therefore, the heat-resistant release sheet 1 composed of the polyimide film 2 is excellent in dimensional stability at high temperatures. From this viewpoint, the heat-resistant release sheet 1 can more reliably respond to a further increase in the thermocompression bonding temperature when thermocompression bonding is performed by the thermal pressing head.

In an industrial thermocompression bonding process, a thermal pressure head is generally disposed in a transport path of an object to be bonded, and the object to be bonded sequentially transported in the transport path is continuously thermocompressed. In this thermocompression bonding step, a strip-shaped heat-resistant release sheet may be fed between the thermal pressing head and the object to be bonded by conveyance. In this case, the heat-resistant release sheet is heated by the heat-pressurizing head, and at the same time, tension is applied in the longitudinal direction by the conveyance. However, the polyimide film has a low elongation due to a tensile force at a high temperature. Therefore, the heat-resistant release sheet 1 having the polyimide film 2 can be stably conveyed at the time of the supply. From this viewpoint, the heat-resistant release sheet 1 can more reliably respond to a further increase in the thermocompression bonding temperature when thermocompression bonding is performed by the thermal pressing head.

The thickness of the polyimide film 2 and the heat-resistant release sheet 1 composed of the polyimide film 2 is 35 μm or less. The heat-resistant release sheet 1 can ensure good thermal conductivity by being composed of the single-layer polyimide film 2 having a thickness of 35 μm or less. The upper limit of the thickness may be 30 μm or less, 25 μm or less, and further 20 μm or less. The lower limit of the thickness is, for example, 5 μm or more, and may exceed 5 μm, be 7 μm or more, and may be 10 μm or more.

In the industrial thermocompression bonding process, as described above, a strip-shaped heat-resistant release sheet may be fed between the heat pressing head and the object to be bonded by conveyance. In this case, a new heat-resistant release sheet is supplied for every 1 thermocompression bonding, in other words, the heat-resistant release sheet is heated from room temperature to the thermocompression bonding temperature for every thermocompression bonding, whereby necessary heat is transferred to the object to be bonded. Therefore, a slight difference in thermal conductivity of the heat-resistant release sheet greatly affects the time required for thermocompression bonding, that is, the working time (work time). Further, the influence is further increased with an increase in the thermocompression bonding temperature, and for example, the manufacturing efficiency and mounting efficiency of the semiconductor chip by the thermocompression bonding process are significantly influenced. However, the heat-resistant release sheet 1 made of the polyimide film 2 can ensure good thermal conductivity. Therefore, according to the heat-resistant release sheet 1, in addition to the demand for further increase in the thermocompression bonding temperature, the demand for shortening the operation time can be more reliably satisfied.

The cushioning property in the thickness direction of the heat-resistant release sheet 1 can be evaluated by indentation hardness of the sheet measured by a so-called "through mode" of thermomechanical analysis (hereinafter referred to as "TMA"). Pass formula A for indentation hardness at 250 ℃ of heat-resistant release sheet 1₂₅₀(％)＝(d₂₅₀/t₀) X 100 degree of indentation A₂₅₀For example, the content is 3% or more, and may be 4% or more, 5% or more, 6% or more, 6.5% or more, 7% or more, and may be 7.5% or more. Degree of indentation A₂₅₀The upper limit of (b) is, for example, 15% or less. Further, the indentation hardness at 300 ℃ of the heat-resistant release sheet 1 is represented by the general formula A₃₀₀(％)＝(d₃₀₀/t₀) X 100 degree of indentation A₃₀₀For example, it is 3% or more, and may be 5% or more, 6% or more, 9% or more, 9.5% or more, 10% or more, 10.5% or more, and may be 11% or more. Degree of indentation A₃₀₀An upper limit of, for example20% or less, and may be 15% or less. Wherein, t₀The thickness of the heat-resistant release sheet 1 at room temperature (20 ℃ C.). d₂₅₀The trace amount of the penetration probe at 250 ℃ to the heat-resistant release sheet 1 was evaluated by TMA based on the following measurement conditions. d₃₀₀The trace amount of the penetrating probe at 300 ℃ to the heat-resistant release sheet 1 was evaluated by TMA based on the following measurement conditions.

[ measurement conditions ]

Measurement mode: penetration mode and temperature measurement

Shape and tip diameter of the penetrating probe: cylindrical and 1mm phi

Application of pressure: 1MPa of

Temperature increase start temperature and temperature increase rate: 20 ℃ and 10 ℃/min

The heat-resistant release sheet 1 has an indentation degree a in the above range₂₅₀And/or A₃₀₀In this case, the thermal compression bonding temperature can be further reliably satisfied when thermal compression bonding is performed by the thermal compression head. In this case, the object to be pressure-bonded can be more uniformly pressurized when the object is thermally pressure-bonded by the thermal pressure head, and thus, for example, the accuracy and efficiency of thermal pressure-bonding of the object to be pressure-bonded can be improved.

The tensile strength of the heat-resistant release sheet 1 is, for example, 200MPa or more, and may be 220MPa or more, 240MPa or more, and further 260MPa or more. The upper limit of the tensile strength is, for example, 500MPa or less. According to the heat-resistant release sheet 1 having a tensile strength in these ranges, the heat-resistant release sheet can be supplied between the heat pressing head and the object to be pressure-bonded more reliably and stably by conveyance.

The maximum tensile elongation of the heat-resistant release sheet 1 is, for example, 200% or less, and may be 180% or less, 150% or less, 100% or less, 50% or less, 40% or less, and further may be 35% or less. The lower limit of the maximum tensile elongation is, for example, 5% or more. According to the heat-resistant release sheet 1 having the maximum tensile elongation in these ranges, when the heat-resistant release sheet 1 is fed between the heat pressing head and the object to be pressure-bonded by conveyance, even when the heat pressing head and/or the object to be pressure-bonded and the heat-resistant release sheet 1 are locally bonded, the sheet 1 can be prevented from following these members due to elongation. In other words, the releasability of the heat-resistant release sheet 1 from the hot pressing head and/or the object to be pressure-bonded can be further improved.

The polyimide film 2 and the heat-resistant release sheet 1 made of the polyimide film 2 are usually non-porous sheets, which are impermeable sheets that do not allow a fluid (fluid) such as water to pass through in the thickness direction. The polyimide film 2 and the heat-resistant release sheet 1 made of the polyimide film 2 may be insulating sheets (non-conductive sheets) based on the high insulating properties of polyimide.

The shape of the heat-resistant release sheet 1 is, for example, a polygon including a square and a rectangle, a circle, an ellipse, and a belt. The corners of the polygon may have a curvature. The shape of the heat-resistant release sheet 1 is not limited to these examples. The polygonal, circular, and elliptical heat-resistant release sheet 1 can be distributed in a single piece, and the strip-shaped heat-resistant release sheet 1 can be distributed in a wound body (roll) formed by winding around a core. The width of the strip-shaped heat-resistant release sheet 1 and the width of a roll body formed by winding the strip-shaped heat-resistant release sheet 1 can be freely set.

The polyimide constituting the polyimide film 2 is, for example, a condensation polymer of tetracarboxylic dianhydride and diamine. The polyimide constituting the polyimide film 2 is not limited to the above examples. When the polyimide is the above condensation polymer, the kinds of tetracarboxylic dianhydride and diamine are not limited. The polyimide constituting the polyimide film 2 is typically an aromatic polyamide.

The heat-resistant release sheet 1 can be produced by a general method for producing a polyimide film, for example. An example of the production method is described below. First, a solution of polyamic acid as a precursor of polyimide is formed from tetracarboxylic dianhydride and diamine. Next, the formed polyamic acid solution is applied to the surface of a substrate sheet. The substrate sheet is composed of, for example, resin, metal, paper, and a composite material thereof. The surface of the substrate sheet to be coated with the polyamic acid solution may be subjected to a peeling treatment for facilitating peeling of the polyimide film from the substrate sheet. The peeling treatment may be performed by a known method. Various known coaters can be used for coating the polyamic acid solution on the substrate sheet. The surface of the substrate sheet may be coated with the polyamic acid solution by immersing the substrate sheet in the polyamic acid solution. Next, the coating film of the polyamic acid solution formed on the surface of the substrate sheet is imidized to form a polyimide thin film. Imidization can be carried out, for example, by heating and/or adding a catalyst. Then, after post-heating for removing the solvent and the like is performed as necessary, the formed polyimide film is peeled from the base sheet to obtain a polyimide film 2. The polyimide film 2 thus obtained may be used as it is as the heat-resistant release sheet 1, or may be used as the heat-resistant release sheet 1 after being subjected to a predetermined treatment. In this method, the thickness of the polyimide film 2 to be obtained can be controlled by the thickness of the polyamic acid solution applied to the substrate sheet.

The heat-resistant release sheet 1 may be composed of a heat-resistant resin other than polyimide. The heat-resistant resin has a melting point of 310 ℃ or higher and/or a glass transition temperature of 210 ℃ or higher. The melting point may be more than 310 ℃ and 315 ℃ or more, 320 ℃ or more, and further 325 ℃ or more. The upper limit of the melting point is, for example, 400 ℃ or lower. The glass transition temperature may be 220 ℃ or higher, 230 ℃ or higher, 240 ℃ or higher, and may be 250 ℃ or higher. The glass transition temperature is, for example, 300 ℃ or lower. In the present specification, the "melting point of the resin" means: the peak temperature of the "endothermic peak by crystal melting" measured when the temperature of the resin is raised at a predetermined temperature raising rate, for example, 10 ℃ per minute in differential scanning calorimetry (hereinafter referred to as "DSC"). In addition, the "glass transition temperature of the resin" in the present specification means: the peak temperature of the "endothermic peak by glass transition" measured when the resin is heated at a predetermined temperature-raising rate, for example, 10 ℃/min in the DSC.

The heat-resistant resin is, for example, at least 1 selected from the group consisting of polyimide, polyetherimide, polysulfone, polyethersulfone, aromatic polyether ketone, and polyamideimide. The heat-resistant resin may be polyimide and/or aromatic polyether ketone. Examples of the aromatic polyether ketone include polyether ether ketone (PEEK), polyether ketone, and polyether ether ketone. The aromatic polyether ketone may be PEEK. Fluorine resins such as Polytetrafluoroethylene (PTFE), polyvinylidene fluoride, Perfluoroalkoxyalkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene (ETFE) may be excluded from the heat-resistant resin.

The heat-resistant release sheet 1 made of a heat-resistant resin film other than the polyimide film 2 may have the same configuration and/or characteristics as those of the heat-resistant release sheet 1 made of the polyimide film 2, except that the heat-resistant resin film has a single-layer structure instead of the single-layer structure of the polyimide film 2. Further, the heat-resistant resin film other than the polyimide film 2 may have the same configuration and/or characteristics as those of the polyimide film 2 except that the material constituting the film is not polyimide but other heat-resistant resin.

The heat-resistant resin film other than the polyimide film 2 can be produced by various film forming methods such as melt extrusion.

From other aspects, the present invention provides a heat-resistant release sheet,

which is a heat-resistant release sheet arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressed by the heat pressing head, for preventing the object to be pressure-bonded and the heat pressing head from being fixed,

which is composed of a single-layer heat-resistant resin film having a thickness of 35 μm or less,

the heat-resistant resin constituting the heat-resistant resin film is at least 1 selected from the group consisting of polyimide, polyetherimide, polysulfone, polyethersulfone, aromatic polyether ketone, and polyamideimide.

The heat-resistant release sheet may have the same configuration and/or characteristics as those of the heat-resistant release sheet 1 composed of the polyimide film 2.

[ use of Heat-resistant Release sheet ]

As shown in fig. 2, the heat-resistant release sheet 1 can be used as a heat-resistant release sheet that is disposed between the hot pressing head 21 and the object 22 to be pressed when the object 22 to be pressed is thermocompressed by the hot pressing head 21, and prevents the fixation of both. The heat-resistant release sheet 1 is excellent in releasability. According to the heat-resistant release sheet 1, it is possible to prevent fixation (heat fixation) of the sheet 1 to the thermal pressing head 21 and/or the object 22 to be pressure-bonded, which is caused by heat at the time of thermocompression bonding.

The heat-resistant release sheet 1 can be fed and disposed between the heat pressing head 21 and the object 22 to be pressure-bonded by conveyance. The heat-resistant release sheet 1 supplied and arranged by conveyance is, for example, in a belt shape.

The object 22 to be pressure-bonded is, for example, a semiconductor chip, a PCB, or an electronic component. The heat-resistant release sheet 1 can be used for, for example, the manufacture and flip chip mounting of semiconductor chips by thermocompression bonding, the manufacture of PCBs, and the connection of electronic components, and the like.

The heating set temperature of the hot pressing head 21 at the time of thermocompression bonding, in other words, the use temperature of the heat-resistant release sheet 1, may be 250 ℃. The use temperature may be 260 ℃ or higher, 270 ℃ or higher, 280 ℃ or higher, 290 ℃ or higher, and further 300 ℃ or higher. The use temperature of the heat-resistant release sheet 1 is not limited to these ranges.

[ Hot Press bonding method ]

The object 22 to be pressure-bonded can be subjected to thermocompression bonding using the heat-resistant release sheet 1 of the present invention. This thermocompression bonding method is a thermocompression bonding method for the object 22 to be bonded by the thermal pressing head 21, and the object 22 to be bonded is thermocompression bonded by the thermal pressing head 21 in a state where the heat-resistant release sheet 1 is arranged between the thermal pressing head 21 and the object 22 to be bonded. For example, the heat-resistant release sheet 1 can be supplied and disposed between the thermal pressing head 21 and the object 22 to be pressure-bonded by conveyance.

[ method for producing thermocompression bonded article ]

The heat-resistant release sheet 1 of the present invention can be used to produce a thermocompression bonded product. The manufacturing method of the thermal compression bonding object comprises the following steps: the heat-resistant release sheet 1 is arranged between the hot pressing head 21 and the object 22 to be pressure-bonded, and the object 22 to be pressure-bonded is subjected to thermocompression bonding using the hot pressing head 21, thereby obtaining a thermocompression bonded body of the object 22 to be pressure-bonded, that is, a thermocompression bonded body. Examples of thermocompression bonds are PCBs and electronic components.

Examples

The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples.

First, a method for evaluating the heat-resistant release sheet produced in this example is shown.

[ releasability at the time of thermocompression bonding ]

The mold release properties at the time of thermocompression bonding were evaluated as follows.

On a base of a thermocompression bonding apparatus (FC-3000W, product of dongli engineering corporation) having a thermal pressure head and a base, a semiconductor chip (7.3 mm × 7.3mm in size and 725 μm in thickness) was disposed as a pseudo pressure bonding object, and a heat-resistant release sheet as an evaluation object cut to 75mm × 75mm in size was further disposed on the semiconductor chip. The heat-resistant release sheet is disposed so that the semiconductor chip is located at the approximate center of the heat-resistant release sheet when viewed from a direction perpendicular to the disposition surface of the base. The set temperature of the susceptor was set to 120 ℃. Next, the thermal pressure head was lowered so that the pressure was 20N, and then the head was heated to 300 ℃ to perform a thermal compression bonding test for 10 seconds, to evaluate whether or not the thermal fixing of the heat-resistant release sheet to the thermal pressure head or the semiconductor chip as the object to be bonded occurred. The heat-resistant release sheet after the thermocompression bonding test was judged to have good releasability (o) when peeled from the thermal press head or the semiconductor chip naturally or by pulling the sheet with a hand, and was judged to have failed to peel when peeled without pulling the sheet with a hand (x).

[ thermal conductivity at the time of thermocompression bonding ]

The thermal conductivity at the time of thermocompression bonding was evaluated as follows. A specific evaluation method will be described with reference to fig. 3.

Assuming a pseudo flip chip mounting, a silicon base 52 (thickness: 360 μm), an adhesive sheet 53 (EM-350 ZT-P, thickness: 60 μm) assumed to be NCF, and a semiconductor chip 54 (size: 7.3 mm. times.7.3 mm, thickness: 725 μm) were disposed in this order on a base 51 of a thermocompression bonding apparatus (FC-3000W, manufactured by Toray engineering Co., Ltd.) including a thermal head 57 and the base 51. A thermocouple 55 for measuring the maximum reaching temperature of the adhesive sheet 53 in the thermocompression bonding test is embedded in the adhesive sheet 53. The thermocouple 55 is disposed such that a measuring portion at the tip thereof is located substantially at the center of the adhesive sheet 53 when viewed in a direction perpendicular to the disposition surface of the susceptor 51. Next, a heat-resistant release sheet 56 cut to 150mm × 150mm in size as an evaluation target was disposed on the semiconductor chip 54. The heat-resistant release sheet 56 is disposed so that the semiconductor chip 54 is positioned at the substantially center of the heat-resistant release sheet 56 when viewed from the direction perpendicular to the disposition surface of the base 51. The set temperature of the susceptor 51 was set to 120 ℃. Next, after the hot pressing head 57 was lowered so that the pressing pressure reached 20N, the head was heated to 300 ℃ to perform a thermocompression bonding test for 10 seconds, the maximum reaching temperature of the adhesive sheet 53 at the time of the test was measured by the thermocouple 55, and the thermal conductivity of the heat-resistant release sheet at the time of thermocompression bonding using the hot pressing head was evaluated based on the measured maximum reaching temperature.

[ Heat resistance ]

The heat resistance was evaluated by pressing the tip of a soldering iron set to 280 ℃, 290 ℃ or 300 ℃. Specifically, the tip of the iron set to each temperature was pressed against the surface of the heat-resistant release sheet to be evaluated for 10 seconds, and a case where the surface of the heat-resistant release sheet was not melted by the heat of the iron was judged as good in heat resistance (o), and a case where the surface was melted was judged as failed in heat resistance (x).

[ cushioning properties in thickness direction (indentation hardness) ]

As the cushioning properties in the thickness direction at each temperature of 250 ℃ and 300 ℃, the indentation degree A was evaluated by the above-described method₂₅₀And degree of indentation A₃₀₀. Specifically, the following is shown. First, a heat-resistant release sheet to be evaluated was cut into a square of 7mm × 7mm to obtain a test piece. Then, as the thickness t₀The thickness of the test piece was measured by a micrometer (manufactured by MITUTOYO corporation). Next, a test piece was placed on an evaluation stage of a TMA measuring apparatus (manufactured by BRUKER, TMA4000S), and the indentation amounts d of the penetration probe at 250 ℃ and 300 ℃ to the test piece were measured using a cylindrical penetration probe having a diameter of 1mm in a penetration mode and a measurement mode of temperature rise measurement₂₅₀And d₃₀₀. The applied pressure applied to the test piece was set to a predetermined pressure of 1MPa, the temperature increase start temperature was set to 20 ℃, and the temperature increase rate was set to 10 ℃/min. And, based on the measured thickness t₀And the amount of indentation d₂₅₀、d₃₀₀Respectively by the formula A₂₅₀(％)＝(d₂₅₀/t₀) X 100 to determine the degree of indentation A₂₅₀Through the formula A₃₀₀(％)＝(d₃₀₀/t₀) X 100 to determine the degree of indentation A₃₀₀。

[ tensile Strength and maximum tensile elongation ]

The tensile strength (tensile breaking strength) and the maximum tensile elongation were determined by a tensile test using a tensile tester (AG-I, Shimadzu corporation). The stretching direction is the longitudinal direction (MD direction) of the heat-resistant release sheet. The shape of the test piece was a dumbbell No. 1 as defined in JIS K6251: 1993. The measurement conditions were: the measurement temperature was 25 ℃, the distance between the standards of the test piece was 40mm, the distance between the jigs was 70mm, and the drawing speed was 200 mm/min. The maximum tensile elongation is calculated from the distance between the above-mentioned marks before the test and the distance between the marks at the time of breaking.

(example 1)

A polyimide film (KAPTON 100H, manufactured by Dupont-Toray) having a thickness of 25 μm was prepared as the heat-resistant release sheet of example 1.

(example 2)

A polyimide film (KAPTON 70H, manufactured by Dupont-Toray) having a thickness of 17.5 μm was prepared as the heat-resistant release sheet of example 2.

Comparative example 1

A PFA film (NEOFLON PFA AF-0025, product of Daikin Industries) having a thickness of 25 μm was prepared as the heat-resistant release sheet of comparative example 1.

(example 3)

A polyimide film (KAPTON 50H, manufactured by Dupont-Toray) having a thickness of 12.5 μm was prepared as the heat-resistant release sheet of example 3.

(example 4)

A PEEK Film (Shin-Etsu Polymer Co., Ltd., manufactured by Ltd., Shin-Etsu Sepla Film) having a thickness of 25 μm was prepared as the heat-resistant release sheet of example 4.

The evaluation results of the properties of the heat-resistant release sheets of examples and comparative examples are shown in table 1 below. The thermal conductivity (maximum reaching temperature) of comparative example 1 could not be measured because the heat-resistant release sheet melted.

[ Table 1]

As shown in table 1, the heat-resistant release sheets of examples were excellent in heat resistance and releasability, and also exhibited excellent thermal conductivity in a thermal conductivity test assuming thermocompression bonding by a thermal pressing head. In the heat-resistant release sheet of comparative example 1 composed of a PFA thin film, the indentation degree a was₂₅₀Becomes negative, indentation degree A₃₀₀To a positive value, which reflects: the PFA film exhibits significant thermal expansion in a temperature range of 200 to 280 ℃, and then rapidly thermally softens at a temperature of 280 ℃ or higher.

Industrial applicability

The heat-resistant release sheet of the present invention can be disposed between a thermal pressing head and an object to be pressure-bonded when the object to be pressure-bonded is thermally pressed by the thermal pressing head, and can be used for preventing the fixation of the thermal pressing head and the object to be pressure-bonded. Thermocompression bonding using the heat-resistant release sheet of the present invention can be applied to, for example, manufacturing of semiconductor chips, flip chip mounting, manufacturing of PCBs, and connection of electronic components.