Method for manufacturing adhesive film and electronic device

Abstract

The adhesive film (50) of the present invention is an adhesive film comprising a base layer (10), an adhesive resin layer (A) provided on the first surface (10A) side of the base layer (10), and an adhesive resin layer (B) provided on the second surface (10B) side of the base layer (10) and whose adhesive strength decreases in response to an external stimulus, and has a shrinkage percentage of 0.0% or more and 0.40% or less in the direction in which the thermal shrinkage of the adhesive film (50) is maximum, measured in accordance with JIS C2151 under conditions of heating at 150°C for 30 minutes.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an adhesive film and an electronic device. [Background technology]

[0002] BACKGROUND ART Fan-out type WLP (wafer level package) has been developed as a technology that can reduce the size and weight of electronic devices (for example, semiconductor devices). In eWLB (Embedded Wafer Level Ball Grid Array), one of the methods for fabricating fan-out WLPs, multiple electronic components such as semiconductor chips are temporarily fixed at a distance from each other on an adhesive film attached to a support substrate, and then the multiple electronic components are collectively encapsulated with an encapsulant. Here, the adhesive film must be adhered to the electronic components and support substrate during the encapsulation process, and after encapsulation, it must be removed from the encapsulated electronic components along with the support substrate.

[0003] Techniques relating to the manufacturing method of such a fan-out WLP include, for example, the one described in Patent Document 1 (JP 2011-134811 A).

[0004] Patent Document 1 describes a heat-resistant adhesive sheet for use in manufacturing semiconductor devices that is adhered when resin-encapsulating a substrateless semiconductor chip, the heat-resistant adhesive sheet having a base layer and an adhesive layer, the adhesive layer having an adhesive strength to SUS304 of 0.5 N / 20 mm or more after lamination, and hardening due to stimuli received up to the point at which the resin-encapsulating process is completed, so that the peel strength to the package is 2.0 N / 20 mm or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-134811 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the inventors' investigations, it has become clear that when electronic components are placed on an adhesive film and sealed with a sealing material, the position of the electronic components may shift (hereinafter also referred to as "misalignment of the electronic components"). The present invention has been made in view of the above circumstances, and provides an adhesive film that can suppress displacement of electronic components during the sealing process. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to achieve the above object, and as a result, have found that, in an adhesive film comprising a base layer, an adhesive resin layer (A) provided on a first surface side of the base layer, and an adhesive resin layer (B) provided on a second surface side of the base layer and having adhesive strength reduced by an external stimulus, a measure of shrinkage rate measured by a specific method is effective as a design guideline for the adhesive film to suppress displacement of electronic components during a sealing process, and have completed the present invention.

[0008] According to the present invention, there are provided the following methods for producing a pressure-sensitive adhesive film and an electronic device.

[0009] [1] a substrate layer; an adhesive resin layer (A) provided on the first surface side of the base material layer; An adhesive film comprising an adhesive resin layer (B) provided on the second surface side of the base material layer and having adhesive strength reduced by an external stimulus, An adhesive film having a shrinkage rate of 0.0% or more and 0.40% or less in the direction in which the adhesive film has maximum thermal shrinkage, measured in accordance with JIS C2151 under conditions of heating at 150°C for 30 minutes. [2] In the adhesive film according to the above [1], An adhesive film used to temporarily fix electronic components when the electronic components are sealed with a sealing material in the manufacturing process of electronic devices. [3] In the adhesive film according to the above [1] or [2], The adhesive film, wherein the substrate layer comprises a uniaxially or biaxially oriented polyester film. [4] In the pressure-sensitive adhesive film according to any one of the above [1] to [3], The adhesive resin layer (B) is an adhesive film whose adhesive strength decreases when heated at a temperature exceeding 180°C. [5] In the adhesive film according to the above [4], The adhesive film, wherein the adhesive resin layer (B) contains at least one selected from a gas-generating component and heat-expandable microspheres. [6] In the adhesive film according to any one of the above [1] to [5], An adhesive film, wherein the content of at least one selected from a gas-generating component and heat-expandable microspheres in the adhesive resin layer (A) is 0.1% by mass or less, when the entire adhesive resin layer (A) is taken as 100% by mass. [7] In the adhesive film according to any one of the above [1] to [6], The adhesive resin layer (A) is an adhesive film containing a (meth)acrylic adhesive resin. [8] A step (1) of preparing a structure comprising the adhesive film according to any one of the above [1] to [7], an electronic component attached to the adhesive resin layer (A) of the adhesive film, and a support substrate attached to the adhesive resin layer (B) of the adhesive film; a step (2) of sealing the electronic component with a sealing material; a step (3) of applying an external stimulus to reduce the adhesive strength of the adhesive resin layer (B) to peel off the support substrate from the structure; a step (4) of peeling the adhesive film from the electronic component; A method for manufacturing an electronic device comprising at least [9] In the method for manufacturing an electronic device according to the above [8], The method for manufacturing an electronic device, wherein the sealing material is an epoxy resin-based sealing material. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an adhesive film that can suppress displacement of electronic components during the sealing process. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of the structure of an adhesive film according to an embodiment of the present invention. [Figure 2] 1A to 1C are cross-sectional views schematically illustrating an example of a method for manufacturing an electronic device according to an embodiment of the present invention. [Figure 3] 1A to 1C are cross-sectional views schematically illustrating an example of a method for manufacturing an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are given the same reference numerals and their explanations will be omitted as appropriate. The drawings are schematic and do not correspond to the actual dimensional ratios. Furthermore, unless otherwise specified, the numerical range "A to B" represents A or more and B or less. Furthermore, in this embodiment, "(meth)acrylic" means acrylic, methacrylic, or both acrylic and methacrylic.

[0013] 1. Adhesive film The adhesive film 50 according to this embodiment will be described below. FIG. 1 is a cross-sectional view schematically showing an example of the structure of an adhesive film 50 according to an embodiment of the present invention.

[0014] As shown in FIG. 1, the adhesive film 50 of this embodiment is an adhesive film comprising a base layer 10, an adhesive resin layer (A) provided on the first surface 10A side of the base layer 10, and an adhesive resin layer (B) provided on the second surface 10B side of the base layer 10 and whose adhesive strength decreases in response to an external stimulus, and the shrinkage percentage of the adhesive film 50 in the direction in which thermal shrinkage is maximum, measured in accordance with JIS C2151 under conditions of heating at 150°C for 30 minutes, is 0.0% or more and 0.40% or less. Here, the MD direction of the resin film used to form the base layer 10 tends to be subject to winding stress during film formation, which leaves residual stress after film formation and causes significant shrinkage, so the direction in which the thermal shrinkage of the adhesive film 50 is greatest is often the MD direction of the resin film used to form the base layer 10. Furthermore, when the resin film for forming the base layer 10 is a uniaxially stretched film or a biaxially stretched film, the direction in which the thermal shrinkage of the adhesive film 50 is greatest is often the direction in which the stretching ratio is greatest.

[0015] As described above, the inventors' investigations have revealed that when electronic components are placed on an adhesive film and sealed with a sealing material, displacement of the electronic components may occur.

[0016] The present inventors have conducted extensive research to realize an adhesive film that can suppress displacement of electronic components during the sealing process. As a result, they have found for the first time that, in an adhesive film 50 that includes a base layer 10, an adhesive resin layer (A) provided on the first surface 10A side of the base layer 10, and an adhesive resin layer (B) provided on the second surface 10B side of the base layer 10 and whose adhesive strength decreases in response to an external stimulus, a measure of the shrinkage rate in the direction in which the thermal shrinkage of the adhesive film 50 is maximized, measured under conditions of heating at 150°C for 30 minutes in accordance with JIS C2151, is effective as a design guideline for adhesive films that suppress displacement of electronic components during the sealing process. That is, the adhesive film 50 of this embodiment is configured so that the shrinkage rate in the direction in which the thermal shrinkage of the adhesive film 50 is maximum, measured under conditions of heating at 150°C for 30 minutes in accordance with JIS C2151, is 0.0% or more and 0.40% or less, thereby making it possible to suppress misalignment of electronic components during the sealing process. The reason why the use of the adhesive film 50 according to this embodiment can suppress misalignment of electronic components during the sealing process is not clear, but the following reasons are thought to be the cause. First, in the manufacturing process of electronic devices such as eWLB, after temporarily fixing multiple electronic components on an adhesive film while keeping them spaced apart, a preheating process called pre-baking is usually carried out before the process of sealing the electronic components with a sealing material. According to the inventors' investigations, it was found that during this pre-bake process, the adhesive film attached to the support substrate becomes lifted, mainly on the outer peripheral surface, and this lifting of the adhesive film causes lifting between the adhesive film and the support substrate during the sealing process, resulting in the infiltration of the sealant between the adhesive film and the electronic component. That is, it is thought that the sealing material penetrates between the adhesive film and the electronic component, resulting in displacement of the electronic component during the sealing process. Furthermore, the inventors have found through their investigations that the adhesive film may undergo thermal shrinkage during the pre-baking step and the sealing step. That is, it is thought that the thermal shrinkage of the adhesive film during the pre-baking step and the sealing step causes displacement of the electronic components temporarily fixed on the adhesive film. On the other hand, an adhesive film 50 having a shrinkage rate of 0.0% or more and 0.40% or less in the direction in which thermal shrinkage is greatest is less likely to lift off from the support substrate during the pre-baking process or the sealing process, and gaps are less likely to form between the adhesive film and the support substrate, making it less likely for the sealing material to penetrate.As a result, it is thought that misalignment of electronic components during the sealing process can be suppressed. Furthermore, adhesive film 50 having a shrinkage rate of 0.0% or more and 0.40% or less in the direction in which thermal shrinkage is greatest is less likely to undergo thermal shrinkage during the pre-baking process or the sealing process, and as a result, it is thought that misalignment of electronic components during the sealing process can be suppressed. For the above reasons, it is believed that by using the adhesive film 50 according to this embodiment, it is possible to suppress displacement of electronic components during the sealing process.

[0017] In the adhesive film 50 according to this embodiment, the upper limit of the shrinkage rate in the direction in which the thermal shrinkage of the adhesive film 50 is maximum, measured under conditions of heating at 150°C for 30 minutes, is 0.40% or less, but from the viewpoint of further suppressing misalignment of electronic components during the sealing process, 0.30% or less is preferred, 0.20% or less is more preferred, 0.10% or less is even more preferred, and 0.05% or less is particularly preferred.

[0018] In the adhesive film 50 of this embodiment, the shrinkage rate in the direction in which the thermal shrinkage of the adhesive film 50 is greatest, measured in accordance with JIS C2151 under conditions of heating at 150°C for 30 minutes, can be controlled, for example, by using a film with a low thermal shrinkage rate as the resin film for forming the base layer 10; by subjecting the resin film for forming the base layer 10 to a stress relaxation treatment such as heat treatment to reduce thermal stress; by setting the drying temperature when forming the adhesive resin layer (A) and the adhesive resin layer (B) on the base layer 10 to a higher temperature, thereby reducing the thermal stress of the adhesive resin layer (A), the adhesive resin layer (B) and the base layer 10; etc.

[0019] The total thickness of the adhesive film 50 according to this embodiment is preferably 10 μm or more and 1000 μm or less, more preferably 20 μm or more and 500 μm or less, from the viewpoint of the balance between mechanical properties and ease of handling.

[0020] The adhesive film 50 of this embodiment can be used, for example, as a film for temporarily fixing electronic components when sealing the electronic components with a sealing material in the manufacturing process of an electronic device, and is particularly suitable for use as a film for temporarily fixing electronic components in the manufacturing process of a fan-out type WLP or a fan-out type PLP.

[0021] Next, each layer constituting the adhesive film 50 according to this embodiment will be described.

[0022] <Base material layer> The base layer 10 is a layer provided for the purpose of improving the properties of the adhesive film 50, such as ease of handling, mechanical properties, and heat resistance. The base layer 10 is not particularly limited, but may be, for example, a resin film. The resin constituting the resin film may be one or more of known thermoplastic resins, such as polyolefins (e.g., polyethylene, polypropylene, poly(4-methyl-1-pentene) and poly(1-butene)); polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate); polyamides (e.g., nylon-6, nylon-66 and polymethaxylene adipamide); polyacrylates; polymethacrylates; polyvinyl chloride; polyvinylidene chloride; polyimides; polyetherimides; ethylene-vinyl acetate copolymers; polyacrylonitrile; polycarbonates; polystyrenes; ionomers; polysulfones; polyethersulfones; and polyphenylene ethers. Among these, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred from the viewpoint of an excellent balance of low shrinkage, mechanical strength, price, and the like, and polyethylene terephthalate and polybutylene terephthalate are more preferred.

[0023] The substrate layer 10 may be a single layer or may be made up of two or more layers. Furthermore, the form of the resin film used to form the base layer 10 is preferably a stretched film stretched uniaxially or biaxially, from the viewpoint of providing an excellent balance between the low shrinkage properties and mechanical strength of the base layer 10. As the resin film used to form the base layer 10, from the viewpoint of an excellent balance of low shrinkage, mechanical strength, price, etc., uniaxially oriented or biaxially oriented polyester film is more preferable, and uniaxially oriented or biaxially oriented polyethylene terephthalate (PET) film is particularly preferable.

[0024] The shrinkage percentage of the base material layer 10 in the direction in which the thermal shrinkage is maximum, measured in accordance with JIS C2151 under conditions of heating at 150°C for 30 minutes, is preferably 0.0% or more and 1.3% or less, and more preferably 0.0% or more and 1.3% or less. If the shrinkage percentage of the base material layer 10 in the direction in which the thermal shrinkage is maximum is within the above range, it is preferable because it is easy to control the shrinkage percentage of the adhesive film 50 in the direction in which the thermal shrinkage is maximum within the above range. Here, the MD direction of the resin film used to form the base layer 10 tends to be large due to the stress applied during film formation, which remains after film formation and causes significant shrinkage, so the direction in which the thermal shrinkage of the base layer 10 is greatest is often the MD direction of the resin film used to form the base layer 10. Furthermore, when the resin film for forming the base layer 10 is a uniaxially stretched film or a biaxially stretched film, the direction in which the thermal shrinkage of the base layer 10 is greatest is often the direction in which the stretching ratio is greatest.

[0025] Here, the shrinkage rate in the direction in which the thermal shrinkage of the base layer 10 is greatest can be controlled, for example, by subjecting the resin film used to form the base layer 10 to a stress relaxation treatment such as heat treatment to reduce thermal stress. When the resin film used to form the base layer 10 is a uniaxially or biaxially oriented polyethylene terephthalate (PET) film, the heat treatment temperature is, for example, 140°C or higher and 240°C or lower, and the heat treatment time is, for example, 10 seconds or higher and 200 seconds or lower.

[0026] From the viewpoint of obtaining good film properties, the thickness of the base layer 10 is preferably 1 μm or more and 500 μm or less, more preferably 5 μm or more and 300 μm or less, and even more preferably 10 μm or more and 250 μm or less. The substrate layer 10 may be subjected to a surface treatment to improve adhesion to other layers, such as corona treatment, plasma treatment, undercoat treatment, or primer coat treatment.

[0027] <Adhesive resin layer (A)> The adhesive resin layer (A) is a layer provided on one side of the base layer 10, and is a layer that comes into contact with the surface of an electronic component to temporarily fix the electronic component when sealing the electronic component with a sealing material during the manufacturing process of an electronic device, for example.

[0028] The adhesive resin layer (A) contains an adhesive resin (A1). Examples of the adhesive resin (A1) include (meth)acrylic adhesive resins (a), silicone adhesive resins, urethane adhesive resins, olefin adhesive resins, and styrene adhesive resins. Among these, the (meth)acrylic adhesive resin (a) is preferred from the viewpoint of facilitating adjustment of adhesive strength.

[0029] The adhesive resin layer (A) may be a radiation-crosslinked adhesive resin layer whose adhesive strength is reduced by radiation. The radiation-crosslinked adhesive resin layer is crosslinked by irradiation with radiation, significantly reducing its adhesive strength, making it easier to peel the adhesive film 50 from the electronic component. Examples of radiation include ultraviolet rays, electron beams, and infrared rays. The radiation crosslinkable adhesive resin layer is preferably an ultraviolet crosslinkable adhesive resin layer.

[0030] Examples of the (meth)acrylic adhesive resin (a) used in the adhesive resin layer (A) include copolymers containing (meth)acrylic acid alkyl ester monomer units (a1) and monomer units (a2) having functional groups that can react with a crosslinking agent. In this embodiment, the (meth)acrylic acid alkyl ester means an acrylic acid alkyl ester, a methacrylic acid alkyl ester, or a mixture thereof.

[0031] The (meth)acrylic adhesive resin (a) according to this embodiment can be obtained, for example, by copolymerizing a monomer mixture containing a (meth)acrylic acid alkyl ester monomer (a1) and a monomer (a2) having a functional group capable of reacting with a crosslinking agent.

[0032] Examples of the monomer (a1) that forms the (meth)acrylic acid alkyl ester monomer unit (a1) include (meth)acrylic acid alkyl esters having an alkyl group with about 1 to 12 carbon atoms. Preferably, they are (meth)acrylic acid alkyl esters having an alkyl group with 1 to 8 carbon atoms. Specific examples include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. These may be used alone or in combination of two or more. In the (meth)acrylic adhesive resin (a) according to the present embodiment, the content of the (meth)acrylic acid alkyl ester monomer unit (a1) is preferably 10% by mass or more and 98.9% by mass or less, more preferably 50% by mass or more and 97% by mass or less, and even more preferably 85% by mass or more and 95% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0033] Examples of the monomer (a2) that forms the monomer (a2) having a functional group reactive with a crosslinking agent include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid, itaconic acid monoalkyl ester, mesaconic acid monoalkyl ester, citraconic acid monoalkyl ester, fumaric acid monoalkyl ester, maleic acid monoalkyl ester, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, tert-butylaminoethyl acrylate, and tert-butylaminoethyl methacrylate. Preferred are acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, and the like. These may be used alone or in combination of two or more. In the (meth)acrylic adhesive resin (a) according to this embodiment, the content of the monomer unit (a2) is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 20% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0034] The (meth)acrylic adhesive resin (a) according to this embodiment may further contain, in addition to the monomer unit (a1) and the monomer unit (a2), a bifunctional monomer unit (a3) or a specific comonomer unit having surfactant properties (hereinafter referred to as a polymerizable surfactant). The polymerizable surfactant has the property of copolymerizing with the monomers (a1), (a2) and (a3), and also acts as an emulsifier when emulsion polymerization is carried out.

[0035] Examples of the monomer (a3) that forms the bifunctional monomer unit (a3) include allyl methacrylate, allyl acrylate, divinylbenzene, vinyl methacrylate, vinyl acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tetraethylene glycol di(meth)acrylate, and, for example, those having diacrylate or dimethacrylate at both ends and a propylene glycol main chain structure (e.g., manufactured by NOF Corporation; trade names: PDP-200, PDP-400, ADP-200, ADP-400), tetramethylene glycol (e.g., manufactured by NOF Corporation; trade names: ADT-250, ADT-850), and mixtures thereof (e.g., manufactured by NOF Corporation; trade names: ADET-1800, ADPT-4000).

[0036] In the (meth)acrylic adhesive resin (a) according to the present embodiment, the content of the monomer unit (a3) is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 15% by mass or less, even more preferably 0.1% by mass or more and 20% by mass or less, and particularly preferably 0.1% by mass or more and 5% by mass or less, when the sum of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0037] Examples of polymerizable surfactants include those in which a polymerizable 1-propenyl group has been introduced into the benzene ring of polyoxyethylene nonylphenyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; trade names: Aqualon RN-10, RN-20, RN-30, RN-50, etc.), those in which a polymerizable 1-propenyl group has been introduced into the benzene ring of an ammonium salt of a sulfate ester of polyoxyethylene nonylphenyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; trade names: Aqualon HS-10, HS-20, HS-1025, etc.), and sulfosuccinic acid diesters having a polymerizable double bond in the molecule (manufactured by Kao Corporation; trade names: Latemul S-120A, S-180A, etc.). In the (meth)acrylic adhesive resin (a) according to the present embodiment, the content of the polymerizable surfactant is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 15% by mass or less, even more preferably 0.1% by mass or more and 20% by mass or less, and particularly preferably 0.1% by mass or more and 5% by mass or less, when the sum of all monomer units in the (meth)acrylic adhesive resin (a) is 100% by mass.

[0038] The (meth)acrylic adhesive resin (a) according to the present embodiment may further contain, if necessary, a monomer unit formed from a monomer having a polymerizable double bond, such as vinyl acetate, acrylonitrile, or styrene.

[0039] The polymerization reaction mechanism of the (meth)acrylic adhesive resin (a) according to the present embodiment may be radical polymerization, anionic polymerization, cationic polymerization, etc. Taking into consideration the production cost of the (meth)acrylic adhesive resin (a), the influence of functional groups of the monomers, the influence of ions on the surface of electronic components, etc., polymerization by radical polymerization is preferred. When polymerizing by radical polymerization reaction, the following radical polymerization initiators are used: benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 3,3,5-trimethylhexanoyl peroxide, di-2-ethylhexyl peroxydicarbonate, methyl ethyl ketone peroxide, t-butyl peroxyphthalate, t-butyl peroxybenzoate, di-t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxy-2-hexanoate, t-butyl peroxy Examples of the peroxide include organic peroxides such as di-2-ethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, t-butyl peroxide, and di-t-amyl peroxide; inorganic peroxides such as ammonium persulfate, potassium persulfate, and sodium persulfate; and azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, and 4,4'-azobis-4-cyanovaleric acid.

[0040] When polymerization is performed by emulsion polymerization, among these radical polymerization initiators, inorganic peroxides such as water-soluble ammonium persulfate, potassium persulfate, and sodium persulfate, and azo compounds having a carboxyl group in the molecule such as water-soluble 4,4'-azobis-4-cyanovaleric acid are preferred. Considering the influence of ions on the surface of electronic components, azo compounds having a carboxyl group in the molecule such as ammonium persulfate and 4,4'-azobis-4-cyanovaleric acid are more preferred, and azo compounds having a carboxyl group in the molecule such as 4,4'-azobis-4-cyanovaleric acid are particularly preferred.

[0041] The adhesive resin layer (A) according to this embodiment preferably further contains, in addition to the adhesive resin (A1), a crosslinking agent (A2) having two or more crosslinkable functional groups in one molecule. The crosslinking agent (A2) having two or more crosslinkable functional groups in one molecule is used to react with the functional groups of the adhesive resin (A1) to adjust the adhesive strength and cohesive strength. Examples of such crosslinking agents (A2) include epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, and resorcinol diglycidyl ether; isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate triadduct of trimethylolpropane, polyisocyanate, diphenylmethane diisocyanate, and tolylene diisocyanate; and trimethylolpropane-tri-β-aziridinylpropionate. Examples of suitable aziridine compounds include aziridine compounds such as tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), and trimethylolpropane-tri-β-(2-methylaziridine)propionate; tetrafunctional epoxy compounds such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane; and melamine compounds such as hexamethoxymethylolmelamine. These compounds may be used alone or in combination of two or more. Among these, it is preferable to contain one or more compounds selected from the group consisting of epoxy compounds, isocyanate compounds, and aziridine compounds.

[0042] The content of the crosslinking agent (A2) is usually preferably within a range in which the number of functional groups in the crosslinking agent (A2) is not greater than the number of functional groups in the adhesive resin (A1), but an excess amount may be added as necessary when new functional groups are generated in the crosslinking reaction or when the crosslinking reaction is slow. The content of the crosslinking agent (A2) in the adhesive resin layer (A) is preferably 0.1 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the adhesive resin (A1), from the viewpoint of improving the balance between the heat resistance and adhesion of the adhesive resin layer (A).

[0043] The total content of the adhesive resin (A1) and the crosslinking agent (A2) in the adhesive resin layer (A) is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less, when the entire adhesive resin layer (A) is taken as 100% by mass. This makes it possible to further suppress adhesive residue on the electronic component when peeling the adhesive film from the electronic component.

[0044] The thickness of the adhesive resin layer (A) is not particularly limited, but is preferably, for example, from 1 μm to 100 μm, and more preferably from 3 μm to 50 μm.

[0045] The adhesive resin layer (A) can be formed, for example, by applying an adhesive to the base layer 10. The adhesive may be dissolved in a solvent and applied as a coating liquid, or may be applied as an aqueous emulsion, or the liquid adhesive may be applied directly. Among these, an aqueous emulsion coating liquid is preferred. Examples of the aqueous emulsion coating liquid include a coating liquid obtained by dispersing a (meth)acrylic adhesive resin (a), a silicone adhesive resin, a urethane adhesive resin, an olefin adhesive resin, a styrene adhesive resin, or the like in water. A pressure-sensitive adhesive coating solution dissolved in an organic solvent may also be used. The organic solvent is not particularly limited and may be appropriately selected from known solvents taking into consideration solubility and drying time. Examples of organic solvents include esters such as ethyl acetate and methyl acetate; ketones such as acetone and MEK; aromatic solvents such as benzene, toluene, and ethylbenzene; linear or cyclic aliphatic solvents such as heptane, hexane, and cyclohexane; and alcohols such as isopropanol and butanol. Ethyl acetate and toluene are preferred as organic solvents. These solvents may be used alone or in combination of two or more. The adhesive coating solution can be applied by a conventionally known coating method, such as a roll coater method, a reverse roll coater method, a gravure roll method, a bar coater method, a comma coater method, or a die coater method. The drying conditions for the applied adhesive are preferably a temperature range of 100 to 240°C for 10 seconds to 5 minutes, from the viewpoint of reducing thermal stress in the adhesive resin layer (A) and the base layer 10 and reducing the shrinkage rate of the adhesive film 50. More preferably, the drying is performed at a temperature range of 120 to 200°C for 30 seconds to 3 minutes.

[0046] <Adhesive resin layer (B)> The adhesive film 50 according to this embodiment includes an adhesive resin layer (B) on the second surface 10B of the base layer 10 opposite to the first surface 10A, the adhesive resin layer (B) having adhesive strength that decreases in response to an external stimulus. This allows the adhesive film 50 to be easily peeled off from the support substrate 80 by applying an external stimulus. Here, examples of the adhesive resin layer (B) whose adhesive strength decreases with an external stimulus include a heat-peelable adhesive resin layer whose adhesive strength decreases with heating, a radiation-peelable adhesive resin layer whose adhesive strength decreases with radiation, etc. Among these, a heat-peelable adhesive resin layer whose adhesive strength decreases with heating is preferred. Examples of heat-peelable adhesive resin layers include adhesive resin layers made of a heat-expandable adhesive containing a gas-generating component, a heat-expandable adhesive containing heat-expandable microspheres that can expand to reduce adhesive strength, and a heat-expandable adhesive whose adhesive strength is reduced by a crosslinking reaction of the adhesive component due to heat.

[0047] In this embodiment, the thermally expandable adhesive used in the adhesive resin layer (B) is an adhesive whose adhesive strength decreases or is lost when heated, for example, at a temperature exceeding 180° C. For example, a material can be selected that does not peel at temperatures below 180° C. but peels at temperatures exceeding 180° C., and it is preferable that the adhesive strength is such that the adhesive film 50 does not peel from the support substrate 80 during the manufacturing process of the electronic device. Here, the decrease or loss of adhesive strength due to heating at temperatures above 180°C can be evaluated, for example, by attaching the adhesive resin layer (B) side to a stainless steel plate, heating it at 140°C for 1 hour, and then heating it at a temperature above 180°C for 2 minutes, and then measuring the peel strength from the stainless steel plate. The specific heating temperature when heating at temperatures above 180°C is set to a temperature higher than the temperature at which gas is generated or the temperature at which the heat-expandable microspheres thermally expand, and is appropriately set depending on the type of gas generated and the type of heat-expandable microspheres. In this embodiment, loss of adhesive strength refers, for example, to a 180° peel strength of less than 0.5 N / 25 mm measured at 23°C and a tensile speed of 300 mm / min.

[0048] Examples of gas-generating components that can be used in thermally expandable pressure-sensitive adhesives include azo compounds, azide compounds, and Meldrum's acid derivatives. Other examples include inorganic blowing agents such as ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium boron hydroxide, and various azides; water; fluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxybis(benzene)sulfonylhydrazide, and the like. Other examples of organic blowing agents that can be used include hydrazine compounds such as benzenesulfonyl hydrazide, allyl bis(sulfonyl hydrazide), and the like; semicarbazide compounds such as p-toluylenesulfonyl semicarbazide, 4,4'-oxybis(benzenesulfonyl semicarbazide), and the like; triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole, and the like; and N-nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'-dinitrosoterephthalamide, and the like. The gas-generating component may be added to the adhesive resin (B1), or may be directly bonded to the adhesive resin (B1).

[0049] The heat-expandable microspheres used in heat-expandable pressure-sensitive adhesives can be, for example, microencapsulated blowing agents. Examples of such heat-expandable microspheres include microspheres in which a substance that easily gasifies and expands upon heating, such as isobutane, propane, or pentane, is encapsulated within an elastic shell. Examples of materials constituting the shell include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone. Heat-expandable microspheres can be produced, for example, by coacervation or interfacial polymerization. Heat-expandable microspheres can be added to adhesive resins.

[0050] The content of at least one selected from the gas-generating component and the heat-expandable microspheres can be appropriately set depending on the expansion ratio and adhesive strength reduction of the heat-peelable adhesive resin layer (B), and is not particularly limited, but is, for example, 1 part by mass or more and 150 parts by mass or less, preferably 10 parts by mass or more and 130 parts by mass or less, and more preferably 12 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the adhesive resin (B1) in the heat-peelable adhesive resin layer (B). It is preferable to design the temperature at which gas is generated and the temperature at which the heat-expandable microspheres thermally expand exceed 180°C.

[0051] Examples of the adhesive resin (B1) constituting the thermally expandable adhesive include (meth)acrylic resin (b), urethane resin, silicone resin, polyolefin resin, polyester resin, polyamide resin, fluorine resin, styrene-diene block copolymer resin, etc. Among these, (meth)acrylic resin (b) is preferred.

[0052] Examples of the (meth)acrylic adhesive resin (b) used in the adhesive resin layer (B) include copolymers containing (meth)acrylic acid alkyl ester monomer units (b1) and monomer units (b2) having functional groups that can react with a crosslinking agent. In this embodiment, the (meth)acrylic acid alkyl ester means an acrylic acid alkyl ester, a methacrylic acid alkyl ester, or a mixture thereof.

[0053] The (meth)acrylic adhesive resin (b) according to this embodiment can be obtained, for example, by copolymerizing a monomer mixture containing a (meth)acrylic acid alkyl ester monomer (b1) and a monomer (b2) having a functional group capable of reacting with a crosslinking agent.

[0054] Examples of the monomer (b1) that forms the (meth)acrylic acid alkyl ester monomer unit (b1) include (meth)acrylic acid alkyl esters having an alkyl group with about 1 to 12 carbon atoms. Preferred are (meth)acrylic acid alkyl esters having an alkyl group with 1 to 8 carbon atoms. Specific examples include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. These may be used alone or in combination of two or more. In the (meth)acrylic adhesive resin (b) according to this embodiment, the content of the (meth)acrylic acid alkyl ester monomer unit (b1) is preferably 10% by mass or more and 98.9% by mass or less, more preferably 50% by mass or more and 97% by mass or less, and even more preferably 85% by mass or more and 95% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (b) is 100% by mass.

[0055] Examples of the monomer (b2) that forms the monomer (b2) having a functional group reactive with a crosslinking agent include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid, itaconic acid monoalkyl ester, mesaconic acid monoalkyl ester, citraconic acid monoalkyl ester, fumaric acid monoalkyl ester, maleic acid monoalkyl ester, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, tertiary-butylaminoethyl acrylate, and tertiary-butylaminoethyl methacrylate. Acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, and the like are preferred. These may be used alone or in combination of two or more. In the (meth)acrylic adhesive resin (b) according to this embodiment, the content of the monomer unit (b2) is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 20% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less, when the total of all monomer units in the (meth)acrylic adhesive resin (b) is 100% by mass.

[0056] The (meth)acrylic adhesive resin (b) according to this embodiment may further contain, in addition to the monomer unit (b1) and the monomer unit (b2), a bifunctional monomer unit (b3) or a specific comonomer unit having surfactant properties (hereinafter referred to as a polymerizable surfactant). The polymerizable surfactant has the property of copolymerizing with the monomer (b1), the monomer (b2) and the monomer (b3), and also acts as an emulsifier when emulsion polymerization is carried out.

[0057] Examples of the monomer (b3) that forms the bifunctional monomer unit (b3) include allyl methacrylate, allyl acrylate, divinylbenzene, vinyl methacrylate, vinyl acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tetraethylene glycol di(meth)acrylate, and, for example, those having diacrylate or dimethacrylate at both ends and a propylene glycol main chain structure (e.g., manufactured by NOF Corporation; trade names: PDP-200, PDP-400, ADP-200, ADP-400), tetramethylene glycol (e.g., manufactured by NOF Corporation; trade names: ADT-250, ADT-850), and mixtures thereof (e.g., manufactured by NOF Corporation; trade names: ADET-1800, ADPT-4000).

[0058] In the (meth)acrylic adhesive resin (b) according to this embodiment, the content of the monomer unit (b3) is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 15% by mass or less, even more preferably 0.1% by mass or more and 20% by mass or less, and particularly preferably 0.1% by mass or more and 5% by mass or less, when the sum of all monomer units in the (meth)acrylic adhesive resin (b) is 100% by mass.

[0059] Examples of polymerizable surfactants include those in which a polymerizable 1-propenyl group has been introduced into the benzene ring of polyoxyethylene nonylphenyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; trade names: Aqualon RN-10, RN-20, RN-30, RN-50, etc.), those in which a polymerizable 1-propenyl group has been introduced into the benzene ring of an ammonium salt of a sulfate ester of polyoxyethylene nonylphenyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; trade names: Aqualon HS-10, HS-20, HS-1025, etc.), and sulfosuccinic acid diesters having a polymerizable double bond in the molecule (manufactured by Kao Corporation; trade names: Latemul S-120A, S-180A, etc.). In the (meth)acrylic adhesive resin (b) according to this embodiment, the content of the polymerizable surfactant is preferably from 0.1% by mass to 30% by mass, more preferably from 0.1% by mass to 15% by mass, even more preferably from 0.1% by mass to 20% by mass, and particularly preferably from 0.1% by mass to 5% by mass, when the sum of all monomer units in the (meth)acrylic adhesive resin (b) is taken as 100% by mass.

[0060] The (meth)acrylic adhesive resin (b) according to the present embodiment may further contain, if necessary, a monomer unit formed from a monomer having a polymerizable double bond, such as vinyl acetate, acrylonitrile, or styrene.

[0061] The polymerization reaction mechanism of the (meth)acrylic adhesive resin (b) according to this embodiment may be radical polymerization, anionic polymerization, cationic polymerization, etc. Taking into consideration the production cost of the (meth)acrylic adhesive resin (b), the influence of functional groups of the monomers, the influence of ions on the surface of electronic components, etc., polymerization by radical polymerization is preferred. When polymerizing by radical polymerization reaction, the following radical polymerization initiators are used: benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 3,3,5-trimethylhexanoyl peroxide, di-2-ethylhexyl peroxydicarbonate, methyl ethyl ketone peroxide, t-butyl peroxyphthalate, t-butyl peroxybenzoate, di-t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxy-2-hexanoate, t-butyl peroxy Examples of the peroxide include organic peroxides such as di-2-ethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, t-butyl peroxide, and di-t-amyl peroxide; inorganic peroxides such as ammonium persulfate, potassium persulfate, and sodium persulfate; and azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, and 4,4'-azobis-4-cyanovaleric acid.

[0062] When polymerization is performed by emulsion polymerization, among these radical polymerization initiators, inorganic peroxides such as water-soluble ammonium persulfate, potassium persulfate, and sodium persulfate, and azo compounds having a carboxyl group in the molecule such as water-soluble 4,4'-azobis-4-cyanovaleric acid are preferred. Considering the influence of ions on the surface of electronic components, azo compounds having a carboxyl group in the molecule such as ammonium persulfate and 4,4'-azobis-4-cyanovaleric acid are more preferred, and azo compounds having a carboxyl group in the molecule such as 4,4'-azobis-4-cyanovaleric acid are particularly preferred.

[0063] In order to more stably perform peeling from the support substrate, the adhesive resin layer (B) of this embodiment preferably further contains, in addition to the adhesive resin (B1), a crosslinking agent (B2) having two or more crosslinkable functional groups in one molecule. The crosslinking agent (B2) having two or more crosslinkable functional groups in one molecule is used to react with the functional groups of the adhesive resin (B1) to adjust the adhesive strength and cohesive strength. Examples of such crosslinking agents (B2) include epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, and resorcinol diglycidyl ether; isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate triadduct of trimethylolpropane, polyisocyanate, diphenylmethane diisocyanate, and tolylene diisocyanate; and trimethylolpropane-tri-β-aziridinylpropionate. Examples of suitable aziridine compounds include aziridine compounds such as tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), and trimethylolpropane-tri-β-(2-methylaziridine)propionate; tetrafunctional epoxy compounds such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane; and melamine compounds such as hexamethoxymethylolmelamine. These compounds may be used alone or in combination of two or more. Among these, it is preferable to contain one or more compounds selected from the group consisting of epoxy compounds, isocyanate compounds, and aziridine compounds.

[0064] The content of the crosslinking agent (B2) is usually preferably within a range in which the number of functional groups in the crosslinking agent (B2) is not greater than the number of functional groups in the adhesive resin (B1). However, if necessary, an excess amount of the crosslinking agent (B2) may be added when new functional groups are generated in the crosslinking reaction or when the crosslinking reaction is slow. From the viewpoint of more stable peeling from the support substrate, the content of the crosslinking agent (B2) in the adhesive resin layer (B) is preferably 0.5 parts by mass or more and 4.0 parts by mass or less, and more preferably 1.0 parts by mass or more and 3.0 parts by mass or less, per 100 parts by mass of the adhesive resin (B1).

[0065] The total content of the adhesive resin (B1) and the crosslinking agent (B2) in the adhesive resin layer (B) is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less, when the entire adhesive resin layer (B) is taken as 100% by mass. This makes it possible to further suppress displacement of electronic components during the sealing process.

[0066] The total content of the adhesive resin (B1), the crosslinking agent (B2), and at least one component selected from the gas-generating component and the heat-expandable microspheres in the adhesive resin layer (B) is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less, when the entire adhesive resin layer (B) is taken as 100% by mass.

[0067] Furthermore, in the adhesive film 50 according to this embodiment, from the viewpoint of reducing the adhesive strength of the adhesive resin layer (B) by applying an external stimulus and stably holding the electronic component on the adhesive resin layer (A) when peeling the support substrate from the adhesive resin layer (B), the content of at least one substance selected from gas-generating components and heat-expandable microspheres in the adhesive resin layer (A) is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less, when the entire adhesive resin layer (A) is taken as 100% by mass, and it is particularly preferable that the adhesive resin layer (A) does not contain at least one substance selected from gas-generating components and heat-expandable microspheres.

[0068] From the viewpoint of improving adhesion to the support substrate, the adhesive resin layer (B) according to this embodiment preferably contains a tackifier resin in addition to the adhesive resin (B1). Incorporation of a tackifier resin into the adhesive resin layer (B) is preferred because it facilitates adjustment of adhesion to the support substrate at around room temperature. The tackifier resin preferably has a softening point of 100°C or higher. Specific examples of tackifier resins include rosin-based resins such as rosin derivatives that have been treated with esterification or the like; terpene-based resins such as α-pinene, β-pinene, dipentene, and terpene phenol; natural rosins such as gum, wood, and tall oil; hydrogenated, disproportionated, polymerized, or maleated natural rosins; petroleum resins; and coumarone-indene resins.

[0069] Among these, those having a softening point in the range of 100 to 160°C are more preferred, and those in the range of 120 to 150°C are particularly preferred. Using a tackifier resin having a softening point within this range not only minimizes contamination and adhesive residue on the support substrate, but also further improves adhesion to the support substrate in the working environment. Furthermore, using a polymerized rosin ester-based tackifier resin not only minimizes contamination and adhesive residue on the support substrate, but also improves adhesion to the support substrate in an environment of 80 to 130°C, and allows the heat-expandable microspheres to be more easily peeled from the support substrate after expansion.

[0070] The blending ratio of the tackifier resin is not particularly limited, and may be appropriately selected so as to adjust the elastic modulus of the adhesive resin layer (B) within a desired predetermined numerical range. However, in terms of the elastic modulus and initial peel strength of the adhesive resin layer (B), it is preferably 1 to 100 parts by mass per 100 parts by mass of the adhesive resin (B1). When the blending ratio of the tackifier resin is equal to or greater than the above-mentioned lower limit per 100 parts by mass of the adhesive resin (B1), adhesion to the support substrate during operation tends to be improved. On the other hand, when the blending ratio is equal to or less than the above-mentioned upper limit, attachment to the support substrate at room temperature tends to be improved. In terms of adhesion to the support substrate and attachment at room temperature, it is more preferable that the blending ratio of the tackifier resin be 2 to 50 parts by mass per 100 parts by mass of the adhesive resin (B1). Furthermore, the acid value of the tackifier resin is preferably 30 or less. When the acid value of the tackifier resin is equal to or less than the above-mentioned upper limit, adhesive residue on the support substrate tends to be less likely to be left during peeling.

[0071] The thickness of the adhesive resin layer (B) is not particularly limited, but is preferably, for example, from 5 μm to 300 μm, and more preferably from 20 μm to 150 μm.

[0072] The adhesive resin layer (B) can be formed, for example, by applying an adhesive onto the base layer 10. The adhesive may be dissolved in a solvent and applied as a coating liquid, or may be applied as an aqueous emulsion, or the liquid adhesive may be applied directly. Among these, a pressure-sensitive adhesive coating solution dissolved in an organic solvent is preferred. The organic solvent is not particularly limited, and may be appropriately selected from known solvents taking into consideration solubility and drying time. Examples of organic solvents include esters such as ethyl acetate and methyl acetate; ketones such as acetone and MEK; aromatics such as benzene, toluene, and ethylbenzene; linear or cyclic aliphatics such as heptane, hexane, and cyclohexane; and alcohols such as isopropanol and butanol. Ethyl acetate and toluene are preferred as organic solvents. These solvents may be used alone or in combination of two or more. The adhesive coating solution can be applied by a conventionally known coating method, such as a roll coater method, a reverse roll coater method, a gravure roll method, a bar coater method, a comma coater method, or a die coater method. The drying conditions for the applied adhesive are preferably a temperature range of 100 to 240°C for 10 seconds to 5 minutes, from the viewpoint of reducing thermal stress in the adhesive resin layer (B) and the base layer 10 and reducing the shrinkage rate of the adhesive film 50. More preferably, the drying conditions are a temperature range of 120 to 200°C for 30 seconds to 3 minutes. Here, when the adhesive resin layer (B) contains at least one selected from a gas-generating component and heat-expandable microspheres, the drying temperature for the applied adhesive is preferably within a range not exceeding the temperature at which gas is generated or the temperature at which the heat-expandable microspheres thermally expand.

[0073] <Other layers> The adhesive film 50 of this embodiment may further include, for example, an irregularity absorbing layer, an impact absorbing layer, an easy-adhesion layer, etc., between the base layer 10 and the adhesive resin layer (A) or between the base layer 10 and the adhesive resin layer (B), as long as the effect of this embodiment is not impaired.

[0074] The irregularity-absorbing layer is preferably formed from natural rubber or synthetic rubber, or synthetic resin having rubber elasticity, having a Shore D hardness according to ASTM D-2240 Shore D of, for example, 50 or less, preferably 40 or less. The thickness of the irregularity-absorbing layer is, for example, 500 μm or less, preferably 5 to 300 μm, more preferably 10 to 150 μm.

[0075] Examples of synthetic rubbers or synthetic resins include nitrile-based, diene-based, and acrylic-based synthetic rubbers, polyolefin-based and polyester-based thermoplastic elastomers, and synthetic resins having rubber elasticity such as ethylene-vinyl acetate copolymers, polyurethanes, polybutadiene, and soft polyvinyl chloride. In this embodiment, even essentially hard polymers such as polyvinyl chloride can be used that have rubber elasticity due to the addition of additives such as plasticizers and softeners. Furthermore, the adhesive resins exemplified above for the adhesive resin layer (A) and the adhesive resin layer (B) can also be preferably used to form the irregularity-absorbing layer.

[0076] 2. Manufacturing method of electronic device Next, a method for manufacturing an electronic device according to this embodiment will be described. Figures 2 and 3 are cross-sectional views that schematically show an example of a method for manufacturing an electronic device according to an embodiment of the present invention. The method for manufacturing an electronic device according to this embodiment includes at least the following four steps. (1) A step of preparing a structure 100 including an adhesive film 50, an electronic component 70 attached to the adhesive resin layer (A) of the adhesive film 50, and a support substrate 80 attached to the adhesive resin layer (B) of the adhesive film 50. (2) A step of sealing the electronic component 70 with the sealing material 60 (3) A step of applying an external stimulus to reduce the adhesive strength of the adhesive resin layer (B) and peeling the support substrate 80 from the structure 100. (4) Step of peeling off the adhesive film 50 from the electronic component 70 In the method for manufacturing an electronic device according to this embodiment, the adhesive film 50 according to this embodiment described above is used as the adhesive film for temporarily fixing the electronic component 70 .

[0077] Each step of the method for manufacturing an electronic device according to this embodiment will be described below.

[0078] (Process (1)) First, a structure 100 is prepared, which includes an adhesive film 50, an electronic component 70 attached to the adhesive resin layer (A) of the adhesive film 50, and a support substrate 80 attached to the adhesive resin layer (B) of the adhesive film 50.

[0079] Such a structure 100 can be fabricated, for example, by the following procedure. First, the adhesive film 50 is attached onto the support substrate 80 so that the adhesive resin layer (B) faces the support substrate 80. A protective film may be attached onto the adhesive resin layer (B), and the protective film can be peeled off, and the exposed surface of the adhesive resin layer (B) can be attached to the surface of the support substrate 80. The support substrate 80 may be, for example, a quartz substrate, a glass substrate, or a SUS substrate.

[0080] Next, the electronic component 70 is placed on the adhesive resin layer (A) of the adhesive film 50 attached to the support substrate 80, whereby the structure 100 can be obtained. Examples of the electronic component 70 include semiconductor chips such as ICs, LSIs, discrete devices, light-emitting diodes, and light-receiving elements, semiconductor panels, and semiconductor packages.

[0081] (Process (2)) Next, the electronic component 70 is sealed with the sealing material 60 . The electronic component 70 is covered with the sealing material 60, and the sealing material 60 is cured at a temperature of, for example, 180°C or lower to seal the electronic component 70. When the adhesive resin layer (B) of the adhesive film 50 contains at least one selected from a gas-generating component and heat-expandable microspheres, the temperature for curing the sealing material 60 is preferably within a range not exceeding the temperature at which gas is generated or the temperature at which the heat-expandable microspheres thermally expand. The form of the sealing material 60 is not particularly limited, but may be, for example, granular, sheet, or liquid.

[0082] The sealing material 60 is not particularly limited, but for example, an epoxy resin-based sealing material using epoxy resin can be used. In particular, a liquid epoxy resin-based sealing material is preferred because it improves the affinity of the sealing material 60 to the adhesive film 50 and enables the electronic component 70 to be sealed more evenly. As such an epoxy resin-based sealing material, for example, T693 / R4000 series, T693 / R1000 series, T693 / R5000 series, etc. manufactured by Nagase ChemteX Corporation can be used.

[0083] Examples of the sealing method include transfer molding, injection molding, compression molding, cast molding, etc. After sealing the electronic component 70 with the sealing material 60, the sealing material 60 is cured by heating at a temperature of, for example, 180° C. or less, to obtain the structure 100 in which the electronic component 70 is sealed.

[0084] (Step (3)) Next, an external stimulus is applied to reduce the adhesive strength of the adhesive resin layer (B), and the support substrate 80 is peeled off from the structure 100. The support substrate 80 can be easily removed from the adhesive film 50, for example, by sealing the electronic component 70 and then heating it to a temperature exceeding 180°C to reduce the adhesive strength of the adhesive resin layer (B).

[0085] (Step (4)) Then, the adhesive film 50 is removed from the electronic component 70 to obtain the electronic device 200. Methods for removing the adhesive film 50 from the electronic component 70 include, for example, a mechanical peeling method, a method in which the adhesive strength of the surface of the adhesive film 50 is reduced before peeling, and the like.

[0086] (Step (5)) The method for manufacturing an electronic device according to this embodiment may further include a step (5) of forming a wiring layer 310 and bumps 320 on the exposed surface of the obtained electronic device 200, thereby obtaining the electronic device 300, as shown in FIG.

[0087] The wiring layer 310 includes pads (not shown) that are external connection terminals formed on the outermost surface, and wiring (not shown) that electrically connects the pads to the exposed electronic components 70. The wiring layer 310 can be formed by a conventionally known method, and may have a multi-layer structure.

[0088] Then, bumps 320 are formed on the pads of the wiring layer 310, thereby obtaining the electronic device 300. Examples of the bumps 320 include solder bumps and gold bumps. Solder bumps can be formed, for example, by placing solder balls on the pads that serve as external connection terminals of the wiring layer 310 and heating them to melt the solder (reflow). Gold bumps can be formed by methods such as ball bonding, plating, and Au ball transfer.

[0089] (Process (6)) The method for manufacturing an electronic device according to this embodiment may further include a step (6) of dicing the electronic device 300 to obtain a plurality of electronic devices 400, as shown in FIG. The electronic device 300 can be diced by a known method.

[0090] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0091] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0092] The present invention will be specifically explained below with reference to examples, but the present invention is not limited thereto.

[0093] Details of the materials used to prepare the adhesive film are as follows.

[0094] <Adhesive resin solution SA1> Deionized pure water was charged with 0.5 parts by weight of 4,4'-azobis-4-cyanovaleric acid (Otsuka Chemical Co., Ltd.; trade name: ACVA) as a polymerization initiator, 78 parts by weight of n-butyl acrylate and 10 parts by weight of methyl methacrylate as monomers (a1), 9 parts by weight of 2-hydroxyethyl methacrylate as monomer (a2), and 3 parts by weight of a polymerizable surfactant (Aqualon HS-1025; Daiichi Kogyo Seiyaku Co., Ltd.; trade name: Aqualon HS-1025) containing a polymerizable 1-propenyl group attached to the benzene ring of the ammonium salt of the sulfate ester of polyoxyethylene nonylphenyl ether. The emulsion was stirred at 70-72°C for 8 hours to obtain an acrylic resin emulsion. The emulsion was neutralized with aqueous ammonia (pH = 7.0) to obtain adhesive resin solution SA1 with a solids concentration of 42.5%.

[0095] <Adhesive resin solution SA2> 0.5 parts by weight of ammonium persulfate as a polymerization initiator, 61 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of n-butyl acrylate, and 9 parts by weight of methyl methacrylate as monomers (a1), 3 parts by weight of 2-hydroxyethyl methacrylate as monomers (a2), 1 part by weight of polytetramethylene glycol diacrylate (NOF Corporation; trade name: ADT-250) as monomer (a3), and 2 parts by weight of a polymerizable surfactant (Aqualon HS-1025; trade name: Aqualon HS-1025) of the ammonium salt of the sulfate ester of polyoxyethylene nonylphenyl ether with a polymerizable 1-propenyl group attached to the benzene ring) were added to deionized pure water and emulsion polymerization was carried out with stirring at 70–72°C for 8 hours to obtain an acrylic resin emulsion. This was neutralized with aqueous ammonia (pH = 7.0) to obtain adhesive resin solution SA2 with a solids concentration of 56.5%.

[0096] <Adhesive coating liquid A1> 55 parts by mass of adhesive resin solution SA1, 45 parts by mass of adhesive resin solution SA2, 0.5 parts by mass of dimethylethanolamine, and 4 parts by mass of an epoxy compound (Ex-1610, manufactured by Nagase ChemteX Corporation) serving as a crosslinking agent were mixed together to obtain adhesive coating solution A1.

[0097] <Adhesive resin solution SB1> In a mixed solvent containing ethyl acetate and toluene, 0.5 parts by weight of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation; trade name: Perbutyl O (registered trademark)) as a polymerization initiator, 35 parts by weight of 2-ethylhexyl acrylate, 40 parts by weight of n-butyl acrylate, and 15 parts by weight of ethyl acrylate as monomers (b1), and 10 parts by weight of 2-hydroxyethyl methacrylate as monomers (b2) were added, and solution polymerization was carried out with stirring at 83 to 87°C for 11 hours to obtain an acrylic resin solution with a solids concentration of 45% by weight. This was designated adhesive resin solution SB1.

[0098] <Adhesive coating liquid B1> 100 parts by mass of the adhesive resin solution SB1 and 0.9 parts by mass (2 parts by mass per 100 parts by mass of the adhesive resin) of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc.; product name: Olestar P49-75S) were mixed, and the solid content was adjusted to 40% with ethyl acetate to obtain adhesive coating solution B1.

[0099] <Adhesive coating liquid B2> Adhesive coating solution B2 was prepared by mixing 100 parts by weight of adhesive resin solution SB1, 2.25 parts by weight of a polymerized rosin ester tackifier (manufactured by Arakawa Chemical Industries, Ltd.; product name: Pencel D-125) (5 parts by weight per 100 parts by weight of adhesive resin), 1.2 parts by weight of an isocyanate crosslinker (manufactured by Mitsui Chemicals, Inc.; product name: Olester P49-75S) (2 parts by weight per 100 parts by weight of adhesive resin), and 6.75 parts by weight of thermally expandable microspheres (manufactured by Sekisui Chemical Co., Ltd.; product name: Advancell EM-503) (15 parts by weight per 100 parts by weight of adhesive resin), and adjusting the solids concentration to 30% with ethyl acetate.

[0100] [Example 1] Adhesive coating liquid A1 was applied to a base layer of polyethylene terephthalate (PET) film 1 (uniaxially stretched film, thickness: 38 μm, shrinkage rate in MD direction: 1.2%, shrinkage rate in TD direction: 0.3% (note that the MD direction was the direction in which thermal shrinkage was greatest). Then, the adhesive coating liquid A1 was applied to the base layer, and the resultant was dried by heating at 120°C for 1 minute to form an adhesive resin layer (A) having a thickness of 10 μm. Next, adhesive coating liquid B1 was applied to the separator, and the resultant was dried by heating at 120°C for 1 minute to form an unevenness-absorbing layer having a thickness of 20 μm. Next, the unevenness-absorbing layer having a thickness of 20 μm was formed on the surface of the PET film 1 opposite the adhesive resin layer (A) via a separator. Adhesive coating liquid B2 was applied thereon, and the resultant was dried by heating at 120°C for 1 minute to form an adhesive resin layer (B) having a thickness of 25 μm. Thus, an adhesive film having an adhesive resin layer (B) was obtained. Here, the PET film 1 has been subjected to stress relaxation treatment by heat treatment. The resulting adhesive film was evaluated as follows, and the results are shown in Table 1.

[0101] [Comparative Example 1] An adhesive film was obtained in the same manner as in Example 1, except that PET film 2 (uniaxially stretched film, thickness: 38 μm, shrinkage rate in MD direction: 1.4%, shrinkage rate in TD direction: 0.3% (note that the MD direction was the direction in which thermal shrinkage was greatest) was used as the base layer instead of PET film 1. Here, the PET film 2 was not subjected to stress relaxation treatment by heat treatment. The resulting adhesive film was evaluated as follows, and the results are shown in Table 1.

[0102] <Evaluation> (1) Measurement of the shrinkage rate of the adhesive film and the base layer The shrinkage rate of the adhesive film and base layer was measured in accordance with JIS C2151, by heating at 150°C for 30 minutes. More specifically, it is as follows. Measurement equipment: Hitachi High-Tech Science TMA-7000 Sample width: 4mm Sample length: 20 mm Pull load: 5g The temperature of the sample was increased by placing it in a movable furnace set at 150°C, and decreased by removing the sample from the furnace.

[0103] (2) Whether or not the adhesive film lifts during pre-baking The adhesive resin layer (B) side of the 10 cm × 10 cm adhesive film obtained in the Examples and Comparative Examples was pressure-bonded to a 10 cm × 10 cm × 1 mm thick mirror-finished stainless steel plate (SUS304BA plate) at a pressure of 0.5 MPa. Next, two glass slides (Muto Chemical Co., Ltd., product name: Slide Glass 1102) measuring 76 mm × 26 mm × 1.0 mm thick were placed 5 mm apart on the center of the adhesive resin layer (A) of the adhesive film and adhered to each other to obtain a structure. The resulting structure was then pre-baked for 30 minutes at 130° C. The structure was then cooled to room temperature, and the presence or absence of the adhesive film lifting from the stainless steel plate was checked and evaluated according to the following criteria. None: No peeling of the adhesive film from the stainless steel plate was observed by visual inspection. Yes: The adhesive film was visually observed to be lifted off the stainless steel plate.

[0104] (3) Misalignment of electronic components during the sealing process The adhesive resin layer (B) side of the adhesive film obtained in the Examples and Comparative Examples was adhered to a stainless steel plate (φ310 mm, thickness 1.5 mm) for compression molding, and 5.0 mm square semiconductor chips were placed on the adhesive resin layer (A) of the adhesive film as electronic components in a grid pattern with 2.0 mm spacing and were adhered to each other to obtain a structure. Next, using a compression molding machine, the multiple semiconductor chips on the adhesive resin layer (A) were encapsulated by compression molding with a liquid epoxy resin-based encapsulant (manufactured by Nagase ChemteX Corporation, product name: T693 / R4212-2C), resulting in a structure in which an encapsulating resin wafer (φ300 mm, thickness 0.5 mm) was formed on a stainless steel plate. Next, the positional deviation of the electronic components was evaluated according to the following criteria. None: No misalignment of the semiconductor chip was observed visually. Present: Misalignment was visually observed in at least part of the semiconductor chip.

[0105] (4) Heat peelability after sealing process The adhesive resin layer (B) side of the 10 cm x 10 cm adhesive film obtained in the Examples and Comparative Examples was pressure-bonded to a mirror-finished stainless steel plate (SUS304BA plate) measuring 10 cm x 10 cm x 1 mm in thickness at a pressure of 0.5 MPa. The resulting structure was then heat-treated at 130°C for 30 minutes to stabilize the adhesive strength of the adhesive resin layer (A) and the adhesive resin layer (B). The structure was then cooled to room temperature. The structure was then heated on a hot plate at 190°C for 2 minutes, and the adhesive film was then peeled off from the stainless steel plate at 23°C and a pulling rate of 300 mm / min to measure the 180° peel strength. The adhesive film was evaluated for its ability to be peeled off from the stainless steel plate by heating according to the following criteria. Acceptable: 180° peel strength is less than 0.5N / 25mm No: 180° peel strength is 0.5N / 25mm or more [Table 1]

[0106] In the examples using adhesive films with a shrinkage rate in the range of 0.0% to 0.40%, no lifting from the support substrate was observed during pre-baking, and no misalignment of the semiconductor element was observed during the encapsulation process. Therefore, it can be seen that the adhesive films of the examples can suppress misalignment of electronic components during the encapsulation process. In contrast, in the comparative example using an adhesive film with a shrinkage rate exceeding 0.40%, misalignment of the semiconductor element was observed during the sealing process. Therefore, it can be understood that the adhesive film of the comparative example causes misalignment of the electronic component during the sealing process.

[0107] This application claims priority based on Japanese Patent Application No. 2018-190041, filed on October 5, 2018, the disclosure of which is incorporated herein by reference in its entirety. [Explanation of symbols]

[0108] A Adhesive resin layer B Adhesive resin layer 10 Base material layer 10A 1st side 10B 2nd side 50 adhesive film 60 Encapsulating material 70 Electronic Components 80 Support substrate 100 structures 200 Electronic equipment 300 Electronic equipment 310 wiring layer 320 Bump 400 Electronic equipment

Claims

1. a substrate layer; an adhesive resin layer (A) provided on the first surface side of the base material layer; An adhesive film comprising: an adhesive resin layer (B) provided on the second surface side of the base material layer and having an adhesive strength reduced by an external stimulus; a shrinkage rate of the pressure-sensitive adhesive film in a direction in which thermal shrinkage is maximum, measured in accordance with JIS C2151 under conditions of heating at 150°C for 30 minutes, of 0.0% or more and 0.40% or less; the adhesive resin layer (A) contains a (meth)acrylic adhesive resin, the substrate layer comprises a uniaxially or biaxially oriented polyester film, The resin constituting the polyester film is at least one selected from polyethylene terephthalate and polybutylene terephthalate, An adhesive film used to temporarily fix electronic components when sealing the electronic components with a sealing material in a manufacturing process of an electronic device, An adhesive film having a shrinkage rate of 1.2% or more and 1.3% or less in a direction in which the thermal shrinkage of the base layer is maximum, measured under conditions of heating at 150°C for 30 minutes in accordance with JIS C2151.

2. The adhesive film according to claim 1, The adhesive resin layer (B) is an adhesive film whose adhesive strength decreases when heated at a temperature exceeding 180°C.

3. The adhesive film according to claim 2, The adhesive resin layer (B) comprises at least one selected from the group consisting of a gas-generating component and heat-expandable microspheres.

4. The adhesive film according to any one of claims 1 to 3, An adhesive film, wherein the content of at least one selected from a gas-generating component and heat-expandable microspheres in the adhesive resin layer (A) is 0.1% by mass or less, when the entire adhesive resin layer (A) is taken as 100% by mass.

5. A step (1) of preparing a structure comprising the adhesive film according to any one of claims 1 to 4, an electronic component attached to the adhesive resin layer (A) of the adhesive film, and a support substrate attached to the adhesive resin layer (B) of the adhesive film; (2) a step of sealing the electronic component with a sealing material; a step (3) of applying an external stimulus to reduce the adhesive strength of the adhesive resin layer (B) to peel off the support substrate from the structure; (4) peeling the adhesive film from the electronic component; A method for manufacturing an electronic device comprising at least

6. 6. The method for manufacturing an electronic device according to claim 5, The method for manufacturing an electronic device, wherein the sealing material is an epoxy resin-based sealing material.

Images