阅读说明：本技术 半导体装置制造用粘接片及使用其的半导体装置的制造方法 (Adhesive sheet for manufacturing semiconductor device and method for manufacturing semiconductor device using the same ) 是由 近藤恭史 付文峰 松永佑规 于 2019-02-12 设计创作，主要内容包括：本发明提供一种粘接片及使用其的半导体装置的制造方法,该粘接片在剥离工序之前,即使受到伴随QFN组装的热历程,也充分且稳定地粘贴,而不会从引线框的背面及密封树脂的背面剥离,也不会泄漏密封树脂,而且,在剥离工序中能够容易地剥离,不会产生粘接剂残留的残胶,或断裂。半导体装置制造用粘接片具备基材和设置于该基材的一个面的热固化型粘接剂层,能够剥离地粘贴于半导体装置的引线框或配线基板,所述半导体装置制造用粘接片中,所述粘接剂层含有含羧基的丙烯腈-丁二烯共聚物(a)、具有下述结构式(1)的环氧树脂(b)和含2个以上马来酰亚胺基的化合物(c),未反应的马来酰亚胺残留量为0.02～0.13。<Image he="516" wi="700" file="DDA0002574824210000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention provides an adhesive sheet and a method for manufacturing a semiconductor device using the same, wherein the adhesive sheet is sufficiently and stably adhered before a peeling process even if subjected to a thermal history accompanying QFN assembly, does not peel off from the back surface of a lead frame and the back surface of a sealing resin, does not leak the sealing resin, and is used for manufacturing a semiconductor deviceThe peeling step can be easily performed, and adhesive residue or breakage does not occur. An adhesive sheet for manufacturing a semiconductor device, which comprises a base material and a thermosetting adhesive layer provided on one surface of the base material and can be peeled off and adhered to a lead frame or a wiring board of a semiconductor device, wherein the adhesive sheet for manufacturing a semiconductor device comprises a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1) and a compound (c) containing 2 or more maleimide groups, and the amount of unreacted maleimide groups remaining is 0.02 to 0.13.)

1. An adhesive sheet for manufacturing a semiconductor device, comprising a base material and a thermosetting adhesive layer provided on one surface of the base material, and being capable of being peeled off and adhered to a lead frame or a wiring board of a semiconductor device, wherein the adhesive layer contains a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and a compound (c) containing 2 or more maleimide groups, and the amount of unreacted maleimide groups remaining is 0.02 to 0.13,

2. the adhesive sheet for manufacturing a semiconductor device according to claim 1, wherein the component (a) is a carboxyl group-containing acrylonitrile-butadiene copolymer having an acrylonitrile content of 5 to 50 mass% and a carboxyl group equivalent weight calculated from a number average molecular weight of 100 to 20000.

3. The adhesive sheet for manufacturing a semiconductor device according to claim 1, wherein the total of the component (b) and the component (c) is 20 to 300 parts by mass based on100 parts by mass of the component (a).

4. A method for manufacturing a semiconductor device, using the adhesive sheet for manufacturing a semiconductor device according to claim 1, the method comprising:

a bonding step of bonding an adhesive sheet for manufacturing a semiconductor device to a lead frame or a wiring board;

a die bonding step of mounting a semiconductor element on the lead frame or the wiring board;

a wire bonding step of connecting the semiconductor element and an external connection terminal;

a sealing step of sealing the semiconductor element with a sealing resin; and

and a peeling step of peeling the adhesive sheet for manufacturing a semiconductor device from the lead frame or the wiring board after the sealing step.

Technical Field

The present invention relates to an adhesive sheet suitable for use as a masking tape when a semiconductor device is assembled by a QFN (Quad Flat Non-lead) method, and a method for manufacturing a semiconductor device using the same.

The present application is based on the priority claim of Japanese patent application No. 2018-022641, filed in Japan on 12/2/2018, and the contents of which are incorporated herein by reference.

Background

In recent years, demands for miniaturization, thinning, and multi-functionalization of IT devices typified by mobile phones have increased, and there is an increasing need for higher-density mounting technology in semiconductor devices (semiconductor packages).

The QFN system has attracted attention as a CSP (Chip Size Package) technology that satisfies this requirement (see patent documents 1 and 2). Particularly, the low pin type below 100 pins is being widely adopted.

Among these, the following methods are generally known as a method of assembling a QFN package in general according to the QFN system. First, in the bonding step, an adhesive sheet is bonded to one surface of a lead frame, and then, in the die bonding step, semiconductor devices such as IC chips are mounted on a plurality of semiconductor device mounting portions (pad portions) formed on the lead frame. Next, in the wire bonding step, a plurality of leads arranged along the outer periphery of each semiconductor element mounting portion of the lead frame and the semiconductor element are electrically connected by bonding wires. Next, in the sealing step, the semiconductor element mounted on the lead frame is sealed with a sealing resin. Thereafter, in the peeling step, the adhesive sheet is peeled from the lead frame, whereby a QFN unit in which a plurality of QFN packages are arranged can be formed. Finally, in the cutting process, a plurality of QFN packages can be manufactured by cutting the QFN units along the periphery of each QFN package.

Adhesive sheets for such use require: the adhesive sheet is sufficiently and stably adhered before the peeling step without peeling from the back surface of the lead frame and the back surface of the sealing resin, and can be easily peeled in the peeling step without causing troubles such as adhesive residue on the back surface of the lead frame or the back surface of the sealing resin, or adhesive sheet breakage.

In particular, in recent years, lead frames made of copper alloys have been used to reduce the cost of semiconductor devices. Such a lead frame made of a copper alloy also has a catalytic action of oxidation degradation on a polymer material of copper as a transition metal, and the adhesive is easily oxidized and degraded by a thermal history accompanying the QFN package assembly after the taping process, and is easily peeled off again and remains of adhesive at the time of sheet peeling.

However, the adhesive sheet used in the past has not sufficiently satisfied a practical level that can be used for a lead frame made of a copper alloy.

For example, there is a conventional adhesive sheet in which an adhesive layer containing an acrylonitrile-butadiene copolymer and a bismaleimide resin is laminated on a base material composed of a heat-resistant film (see patent document 3), and when this adhesive sheet is used, there are problems as follows: the acrylonitrile-butadiene copolymer is easily deteriorated by heat applied in the die attach curing process, the wire bonding process, and the resin sealing process after the taping process, and is difficult to peel off in the peeling process, or the adhesive sheet is broken to cause adhesive residue.

Patent document 1: japanese patent laid-open publication No. 2003-165961

Patent document 2: japanese laid-open patent publication No. 2005-142401

Patent document 3: japanese laid-open patent publication No. 2008-095014

Disclosure of Invention

In view of the above, an object of the present invention is to provide an adhesive sheet that can be sufficiently and stably attached without peeling from the back surface of a lead frame and the back surface of a sealing resin and without leaking the sealing resin even when subjected to a thermal history accompanying QFN assembly before a peeling step, and that can be easily peeled off in the peeling step without generating adhesive residue or breakage, and a method for manufacturing a semiconductor device using the same.

The adhesive sheet for manufacturing a semiconductor device of the present invention comprises a base material and a thermosetting adhesive layer provided on one surface of the base material, and is capable of being peeled off and adhered to a lead frame or a wiring board of a semiconductor device, and is characterized in that the adhesive layer contains a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and a compound (c) containing 2 or more maleimide groups, and the amount of unreacted maleimide groups remaining is 0.02 to 0.13.

[ chemical formula 1]

The component (a) is preferably a carboxyl group-containing acrylonitrile-butadiene copolymer having an acrylonitrile content of 5 to 50 mass% and a carboxyl group equivalent weight calculated from the number average molecular weight of 100 to 20000.

The total amount of the component (b) and the component (c) is preferably 20 to 300 parts by mass per 100 parts by mass of the component (a).

A method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device using the adhesive sheet for manufacturing a semiconductor device described above, including:

a bonding step of bonding an adhesive sheet for manufacturing a semiconductor device to a lead frame or a wiring board;

a die bonding step of mounting a semiconductor element on the lead frame or the wiring board;

a wire bonding step of connecting the semiconductor element and an external connection terminal;

a sealing step of sealing the semiconductor element with a sealing resin; and

and a peeling step of peeling the adhesive sheet for manufacturing a semiconductor device from the lead frame or the wiring board after the sealing step.

According to the present invention, it is possible to provide an adhesive sheet that can be sufficiently and stably attached without peeling from the back surface of a lead frame and the back surface of a sealing resin and without leaking the sealing resin even when subjected to a thermal history accompanying QFN assembly before a peeling step, and that can be easily peeled off in the peeling step without generating adhesive residue or breakage of an adhesive, and a method for manufacturing a semiconductor device using the same.

Drawings

Fig. 1 is a plan view showing an example of a lead frame used in the method for manufacturing a semiconductor device of the present invention.

Fig. 2 is a process diagram for describing a method for manufacturing a semiconductor device of the present invention.

Detailed Description

The present invention will be described in detail below.

[ adhesive sheet for semiconductor device production ]

The adhesive sheet for manufacturing a semiconductor device (hereinafter referred to as adhesive sheet) of the present invention comprises a base material and a thermosetting adhesive layer provided on one surface of the base material, and is capable of being peeled off and adhered to a lead frame or a wiring board of a semiconductor device, wherein the adhesive layer contains a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and a compound (c) containing 2 or more maleimide groups, and the amount of unreacted maleimide remaining is 0.02 to 0.13, and the adhesive sheet is used as a mask tape when a semiconductor device is assembled by the QFN method.

[ chemical formula 2]

The carboxyl group-containing acrylonitrile-butadiene copolymer (a) functions to appropriately maintain the melt viscosity of the adhesive layer at the initial stage of heating, and imparts good flexibility and adhesiveness to the cured adhesive layer, and by containing it, an adhesive layer having good adhesion to a substrate made of a heat-resistant film or the like and having no cracks can be formed. The carboxyl group-containing acrylonitrile-butadiene copolymer (a) may be any known one without limitation, but preferably contains 5 to 50% by mass of acrylonitrile, and more preferably contains 10 to 40% by mass of acrylonitrile. When the acrylonitrile content is less than the above range, the solubility in a solvent or the compatibility with other components is lowered, and therefore, the uniformity of the obtained adhesive layer tends to be lowered. On the other hand, if the acrylonitrile content exceeds the above range, the adhesiveness of the obtained adhesive layer to a lead frame or a sealing resin becomes excessive, and when the adhesive layer is used for an adhesive sheet, the adhesive sheet may be difficult to peel in a peeling step or may be broken.

The carboxyl equivalent weight of the carboxyl group-containing acrylonitrile-butadiene copolymer calculated from the number average molecular weight is preferably in the range of 100 to 20000, more preferably 200 to 10000. If the carboxyl group equivalent is less than the above range, the reactivity with other components is too high, and the storage stability of the resulting adhesive layer tends to be lowered. On the other hand, if the carboxyl group equivalent exceeds the above range, the reactivity with other components is insufficient, and therefore the resulting adhesive layer tends to have a low B-stage. As a result, when the adhesive sheet is used in an adhesive sheet, the viscosity of the adhesive layer is lowered at the initial stage of heating, that is, in the step of sticking the adhesive sheet, the die bonding curing treatment, or the like, and the adhesive layer is likely to be foamed or flow out, thereby lowering the thermal stability.

The carboxyl equivalent weight calculated from the number average molecular weight is a value obtained by dividing the number average molecular weight (Mn) by the number of carboxyl groups per molecule (number of functional groups), and is represented by the following formula.

Carboxyl equivalent (Mn/number of functional groups)

The epoxy resin (b) and the compound (c) having 2 or more maleimide groups bear the thermosetting property of the adhesive layer, and by using them in combination, an adhesive layer having good thermal stability, being easily peelable in the peeling step, and not causing adhesive residue or breakage can be formed. In particular, the epoxy resin (b) imparts toughness to the adhesive layer, and the inclusion thereof can suppress adhesive residue caused by breakage of the adhesive layer in the peeling step.

The compound (c) containing 2 or more maleimide groups imparts thermal stability to the adhesive layer and also functions to adjust the adhesiveness of the adhesive layer, and by containing it, an adhesive layer can be formed in which the adhesiveness is appropriately controlled and which can be easily peeled off in the peeling step.

As a containing 2 or more maleimide compounds (c) specific examples, preferably using a bismaleimide resin compounds, for example can be cited to the following formula (2-1) - (2-3) compounds, especially the following formula (2-1) or (2-3) compounds are useful in the solubility in solvents.

[ chemical formula 3]

As each of the components (a) to (c), a compound composed of 1 kind of compound may be used, or a mixture of 2 or more kinds of compounds may be used.

In the adhesive layer of the adhesive sheet for manufacturing a semiconductor device of the present invention, the residual amount of unreacted maleimide must be 0.02 to 0.13. In particular, the residual amount of unreacted maleimide is preferably 0.02 to 0.10. If the residual amount of unreacted maleimide is less than 0.02, problems such as low initial adhesion strength to the lead frame and generation of an unbonded portion during lamination may occur. On the other hand, if it is higher than 0.13, the initial adhesion strength to the lead frame increases, and as a result, the tape-peeling property after package assembly deteriorates (high peel strength, easy occurrence of adhesive residue, and tape breakage). The adhesive layer can be obtained by appropriately controlling the curing in the drying process during the production of the adhesive layer so that the residual amount of unreacted maleimide is 0.02 to 0.13.

The unreacted maleimide-remaining amount can be obtained by analyzing the result of measuring the adhesive layer by FT-IR spectroscopy (fourier transform infrared spectroscopy). Unreacted maleimide residueThe retention was determined by the peak of maleimide in FT-IR (1148 cm)^-1) Integral value and peak of aromatic ring of maleimide (1500 cm)^-1) The ratio of the integrated values (S1148/S1500) is calculated. The method for analyzing the residual amount of unreacted maleimide is described in detail in the evaluation results of examples.

The ratio of the components is preferably 20 to 300 parts by mass, more preferably 20 to 200 parts by mass, based on100 parts by mass of the total of the component (a), the component (b) and the component (c). If the total amount of the components (b) and (c) is less than the above range, the reactivity of the adhesive layer is lowered, and insolubilization is difficult to proceed even by heating, so that thermal stability is lowered, and the adhesive strength tends to be enhanced. On the other hand, if the amount exceeds the above range, the melt viscosity of the adhesive layer at the initial stage of heating is insufficient, and in the adhesive sheet using the adhesive layer, the adhesive layer may flow out or foam during die attach curing or the like after the taping step.

Further, the mass ratio ((c)/(b)) of the component (c) to the component (b) is preferably in the range of 0.1 to 10. If the content is less than the above range, the obtained adhesive layer tends to undergo a curing reaction at room temperature, and storage stability may deteriorate, or the adhesive strength may become too strong, and an adhesive sheet using the adhesive layer may not be peeled off or may be broken in a peeling step. On the other hand, if the content exceeds the above range, the adhesiveness between the adhesive layer and the base material composed of the heat-resistant film may be reduced, or the adhesive layer may foam, or the obtained adhesive sheet may easily be left.

The adhesive layer in the adhesive sheet for manufacturing a semiconductor device of the present invention may contain a reactive siloxane compound. The reactive silicone compound is used to improve the compatibility of the components constituting the adhesive layer and to improve the peelability of the sealing resin from the adhesive layer, and by containing it, a uniform adhesive layer can be formed in which the components are well compatible and in which troubles such as separation and precipitation of the components do not occur. As a result, the adhesive strength of the adhesive layer becomes uniform, and defects such as a decrease in peelability and adhesive residue due to a high partial adhesive strength can be suppressed.

As the reactive silicone compound, a silicone compound to which reactivity is imparted by a reactive group such as amino modification, epoxy modification, carboxyl modification, mercapto modification, or the like can be used without limitation. Among them, 1, 3-bis (3-aminopropyl) tetramethyldisiloxane, aminopropyl-terminated dimethylsiloxane 4-mer or 8-mer, and bis (3-aminophenoxymethyl) tetramethyldisiloxane are preferable from the viewpoint of rapidly proceeding the reaction with the component (b) and the component (c). The reactive siloxane compound is preferably a compound in which such reactive groups are bonded to both ends of the siloxane structure from the viewpoint of reactivity, but a compound having one end or a silane coupling agent in which one end is reactive and the other end is non-reactive can be used.

The adhesive layer in the adhesive sheet for producing a semiconductor device of the present invention preferably has a ratio of the number of reactive siloxane compounds to the sum of the number of epoxy groups of the component (b) and the number of maleimide groups of the component (c) of 0.05 to 1.2, more preferably 0.1 to 0.8. If the content is less than the above range, the reactivity of the entire adhesive layer is lowered, and the curing reaction is difficult to proceed in die attach curing treatment or the like, and as a result, the adhesive strength may become excessively strong. On the other hand, if the amount exceeds the above range, the reaction proceeds excessively, and problems such as gelation tend to occur during the preparation of the adhesive layer, and the adhesive strength tends to be weak.

In addition to the essential components (a) to (c), a reaction accelerator such as an organic peroxide, imidazole, or triphenylphosphine may be added to the adhesive layer. By adding these components, the state of the adhesive layer at room temperature can be controlled to a good B-stage.

Further, a filler having an average particle diameter of 1 μm or less may be added for the purpose of controlling melt viscosity, improving thermal conductivity, imparting flame retardancy, and the like. Examples of the filler include inorganic fillers such as silica, alumina, magnesia, aluminum nitride, boron nitride, titanium oxide, calcium carbonate, and aluminum hydroxide, and organic fillers such as silicone resins and fluororesins. When the filler is used, the content thereof in the adhesive layer is preferably 1 to 40% by mass.

The adhesive sheet of the present invention has the adhesive layer formed on one surface of the heat-resistant film as a base material.

When producing such an adhesive sheet, first, an adhesive coating is prepared which is composed of at least the above carboxyl group-containing acrylonitrile-butadiene copolymer (a), the epoxy resin (b) having the above structural formula (1), the compound (c) containing 2 or more maleimide groups, and, if necessary, a reactive siloxane compound and a solvent. Then, the coating material is applied to one surface of the heat-resistant film and dried so that the thickness of the adhesive layer after drying is preferably 1 to 50 μm, more preferably 3 to 20 μm. In addition, in order to protect the adhesive layer, it is preferable to further provide a peelable protective film on the formed adhesive layer, and in this case, the adhesive sheet can be produced by a method in which a coating material is applied on the protective film and dried to form the adhesive layer, and a heat-resistant film is provided thereon. When the adhesive sheet is used, the protective film is peeled off.

Examples of the heat-resistant film include heat-resistant plastic films made of polyimide, polyphenylene sulfide, polyether sulfone, polyether ether ketone, liquid crystal polymer, polyethylene terephthalate, polyethylene naphthalate, and the like, composite heat-resistant films made of epoxy resin-glass cloth, and the like, and particularly polyimide films are preferable.

The thickness of the polyimide film is preferably 12.5 to 125 μm, and more preferably 25 to 50 μm. If the hardness is less than the above range, the adhesive sheet tends to have insufficient hardness and to be difficult to handle, and if the hardness exceeds the above range, the work in the taping step or the peeling step in the QFN assembly tends to be difficult.

As the solvent used for the adhesive coating material, 1 or more kinds of organic solvents such as hydrocarbons, alcohols, ketones, ethers (tetrahydrofuran, etc.), and water can be preferably used, and the amount thereof may be appropriately adjusted so as to obtain a suitable viscosity as the coating material. The shape of the coating material may be any of a solution, an emulsion, and a suspension, and may be selected as appropriate depending on the application apparatus used, the environmental conditions, and the like.

Examples of the protective film having releasability include plastic films such as polyethylene, polypropylene, vinyl chloride, fluorine-based resins, and silicone, and films having releasability imparted thereto such as polyethylene terephthalate, polyethylene naphthalate, and paper by silicone coating.

[ method for manufacturing semiconductor device ]

The method for manufacturing a semiconductor device using the adhesive sheet of the present invention includes: a bonding step of bonding an adhesive sheet to the lead frame or the wiring board; a die bonding step of mounting a semiconductor element on a lead frame or a wiring board; a wire bonding step of connecting the semiconductor element and the external connection terminal; a sealing step of sealing the semiconductor element with a sealing resin; and a peeling step of peeling the adhesive sheet from the lead frame or the wiring board after the sealing step.

An example of a method for manufacturing a semiconductor device using the adhesive sheet of the present invention will be described below with reference to fig. 1 to 2. Fig. 1 is a plan view of a lead frame viewed from a side on which a semiconductor device is mounted, and fig. 2(a) to (f) are process views showing a method of manufacturing a QFN package using the lead frame shown in fig. 1, and are a-a' sectional views of the lead frame of fig. 1.

First, a lead frame 20 having a schematic configuration shown in fig. 1 is prepared. In the lead frame 20, a plurality of semiconductor element mounting portions (pad portions) 21 on which semiconductor elements such as IC chips are mounted are formed in a matrix, and a plurality of leads 22 (external connection terminals) are formed along the outer periphery of each semiconductor element mounting portion 21.

As the material of the lead frame 20, there are conventionally known materials, for example, a copper plate and a copper alloy plate, or a material in which a strike plating is provided on them, or a material in which a nickel plating layer, a palladium plating layer, and a gold plating layer are provided in this order on the surface of a copper alloy plate.

As shown in fig. 2 a, an adhesive sheet 10 is attached to one surface (lower surface) of the lead frame 20 so that an adhesive layer (not shown) abuts the lead frame 20 (attaching step). The method of attaching the adhesive sheet 10 to the lead frame 20 includes a lamination method, a press method, and the like, but from the viewpoint of productivity, a lamination method capable of continuously performing a taping process is preferable. The temperature of the adhesive sheet 10 in this step is, for example, from room temperature (5 to 35 ℃) to 150 ℃, and more preferably from 60 to 120 ℃. When the lead frame is attached at a temperature higher than 150 ℃, the lead frame is easily warped.

If the lead frame 20 is warped in this step, positioning in the die attach step or wire bonding step becomes difficult, or transportation to a heating furnace becomes difficult, and the productivity of the QFN package may be lowered.

As shown in fig. 2 b, a semiconductor device 30 such as an IC chip is mounted on the semiconductor device mounting portion 21 of the lead frame 20 through a die attach agent (not shown) on the side to which the adhesive sheet 10 is not attached. At this time, since the warpage is suppressed, the lead frame 20 is easily positioned. Then, the semiconductor element 30 is accurately mounted at a predetermined position. Thereafter, the semiconductor element 30 is fixed and mounted on the semiconductor element mounting portion 21 by heating to about 100 to 200 ℃. At this time, the adhesive layer of the adhesive sheet 10 is cured and adhered to the lead frame.

If a outgas component generated from the adhesive sheet 10, the die attach agent, or the like adheres to the lead frame 20 or the semiconductor element 30, a reduction in yield due to poor wire bonding is likely to occur in the wire bonding step. Therefore, after the die attach process and before the wire bonding process, the lead frame 20 or the semiconductor element 30 is subjected to plasma treatment (plasma cleaning process). As a method of plasma treatment, for example, a lead frame 20 (hereinafter, sometimes referred to as a "green product") to which the adhesive sheet 10 is attached and which is mounted with the semiconductor element 30 is irradiated with plasma in an atmosphere of argon gas or a mixed gas of argon gas and hydrogen gas. The plasma irradiation power in the plasma treatment is, for example, 150 to 600W. The plasma treatment time is, for example, 0.1 to 15 minutes.

As shown in fig. 2 c, the semiconductor element 30 and the lead 22 (external connection terminal) of the lead frame 20 are electrically connected by a bonding wire 31 such as a gold wire, a copper wire, or a copper wire covered with palladium (wire bonding step). The working procedure is carried out while heating the semi-finished product to about 150-250 ℃ on a heating block. The heating time in this step is, for example, 5 to 60 minutes.

When the semi-finished product is heated in the wire bonding step and the fluorine additive is contained in the adhesive layer, the fluorine additive migrates to the surface of the adhesive layer, and therefore the adhesive sheet 10 is easily peeled from the lead frame 20 and the sealing resin 40 in a peeling step described later.

As shown in fig. 2(d), the semi-finished product shown in fig. 2(c) is placed in a mold, and a sealing resin (molding material) is injected into the mold and filled. After an arbitrary amount is filled in the mold, the mold is maintained at an arbitrary pressure, and the semiconductor element 30 is sealed with the sealing resin 40 (sealing step). As the sealing resin, conventionally known materials are used, and for example, a mixture of an epoxy resin and an inorganic filler is used.

As shown in fig. 2 e, the adhesive sheet 10 is peeled off from the sealing resin 40 and the lead frame 20, thereby obtaining a QFN unit 60 in which a plurality of QFN packages 50 are arranged (peeling step).

As shown in fig. 2(f), a plurality of QFN packages 50 are obtained by cutting the QFN units 60 along the periphery of each QFN package 50 (cutting process).

In the above-described embodiments, the method of manufacturing a QFN package using a lead frame was described as an example, but the present invention is not limited to this, and can be applied to a method of manufacturing a semiconductor device other than a QFN package using a lead frame, and a method of manufacturing a semiconductor device using a wiring board.

The adhesive layer in the adhesive sheet of the present invention can be in a B-stage state (semi-cured state) by crosslinking the carboxyl group of the carboxyl group-containing acrylonitrile-butadiene copolymer (a) and the glycidyl group of the epoxy resin (B), and can have a low glass transition temperature (-30 ℃ to 50 ℃). The adhesive sheet having an adhesive layer with a low glass transition temperature can be continuously subjected to a taping process by a roll laminator or the like under heating conditions at relatively low temperatures, specifically at room temperature (5 ℃ to 35 ℃) to 150 ℃, and is excellent in productivity.

In addition, the adhesive layer having a low glass transition temperature (-30 ℃ C. to 50 ℃ C.) in the adhesive sheet of the present invention has a characteristic of high elastic modulus when heated. In recent years, products bonded with a low-cost copper wire or a copper wire covered with palladium instead of a conventional gold wire have been widely used for the purpose of cost reduction in a wire bonding step. Since copper wires or copper wires covered with palladium are metals having higher elasticity than gold, it is necessary to process them under a higher load than conventional gold wires in order to form a stable shape.

When such a large load is applied to the lead frame, if the adhesive layer in the adhesive sheet attached to the lower portion of the lead frame has a low elastic modulus, the adhesive layer is deformed, and resin sealing is performed in the state of the deformed adhesive layer. Then, the sealing resin leaks from the deformed adhesive layer portion. In addition, when the adhesive sheet is peeled from the lead frame, the following problems occur: the adhesive layer is broken from the deformed adhesive layer portion, and the adhesive remains on the surface of the lead frame. Further, when the adhesive has a low elastic modulus at the time of wire bonding, the adhesive is deformed, so that the wire load is hardly transmitted, and wire bonding failure is easily caused. Since the adhesive layer in the adhesive sheet of the present invention has a high elastic modulus as described above, even when wire bonding is performed using a copper wire or a copper wire covered with palladium, problems such as wire bonding failure, leakage of sealing resin, and adhesive layer residue are less likely to occur.

In addition, since the adhesive layer in the adhesive sheet of the present invention contains the compound (c) containing 2 or more maleimide groups and the amount of unreacted maleimide resin remains in a specific range, the adhesive layer can be brought into a high B-stage state, and therefore, the increase in the adhesive strength to the lead frame can be suppressed, and as a result, the leakage of the sealing resin, the adhesive remaining in the lead frame, and the breakage of the adhesive layer at the time of peeling can be suppressed.