Release film and method for manufacturing semiconductor package

Abstract

Provided are: a film comprising a substrate, a base layer, and an adhesive layer in the stated order, the base layer including a cured reaction product of a (meth)acrylic polymer and a curing agent, and the rate of elongation of the base layer, which is derived using the formula (rate of elongation (%))=(elongation (mm) during breakage)×100 / (distance (mm) between grippers before stretching), being 90% or greater as measured at a temperature of 25°C and a speed of 100 mm / min through a stretching test; and a method for manufacturing a semiconductor package in which the aforementioned film is used.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a film and a semiconductor package. [Background technology]

[0002] Semiconductor elements are sealed in a package and mounted on a substrate to protect them from the outside air. A curable resin such as an epoxy resin is used to seal the semiconductor elements. Resin sealing is performed by placing the semiconductor element in a predetermined location in a mold, filling the mold with a curable resin, and curing it. Commonly known sealing methods include transfer molding and compression molding. When sealing semiconductor elements, a release film is often placed on the inner surface of the mold to improve the releasability of the package from the mold. For example, Patent Documents 1 to 3 describe films suitable for manufacturing semiconductor packages. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 133630 [Patent Document 2] International Publication No. 2016 / 093178 [Patent Document 3] International Publication No. 2016 / 125796 Summary of the Invention [Problem to be solved by the invention]

[0004] In semiconductor packages, electronic components such as semiconductor elements, source electrodes, and sealing glass may be exposed from the encapsulating resin to improve heat dissipation or reduce thickness. A typical example of an electronic device with such an exposed portion is a sensor. Semiconductor packages with a portion of the electronic component exposed from the encapsulating resin are manufactured by filling the exposed portion with a curable resin and curing it while the resin is pressed against a mold.

[0005] When a release film is used in the manufacture of a semiconductor package having such an exposed portion, sealing is performed with the film in direct contact with the exposed portion of the electronic component. In this case, when the sealed semiconductor package is peeled from the film, some of the components of the film's adhesive layer may remain attached to the electronic component, contaminating the electronic component. To address the contamination of electronic components due to migration of film components, Patent Document 3 proposes a film comprising a substrate having a specific storage modulus and an adhesive layer containing a reaction-cured product of an acrylic polymer having a specific functional group ratio and a polyfunctional isocyanate compound.

[0006] However, in recent years, with the further increasing complexity of semiconductor package shapes and the increasing height difference of semiconductor packages with exposed parts, the use of films that conform to complex shapes has become more common. In this case, it has been found that as the film stretches, components of the adhesive layer tend to migrate to the encapsulant, resulting in so-called adhesive residue, which can easily contaminate the encapsulant.

[0007] The present disclosure relates to providing a film that can prevent components of an adhesive layer from migrating to an encapsulant even when stretched, and a method for manufacturing a semiconductor package using the film. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> A film comprising a substrate, a foundation layer, and an adhesive layer in this order, the underlayer contains a cured product of a reaction between a (meth)acrylic polymer and a curing agent, A film characterized in that the elongation of the underlayer is 90% or more when measured in a tensile test at 25°C at a speed of 100 mm / min and calculated by the following formula: Elongation (%) = (elongation at break (mm)) x 100 / (distance between grips before tension (mm)) <2> A film comprising a substrate, a foundation layer, and an adhesive layer in this order, the underlayer comprises a reaction-cured product of a (meth)acrylic polymer and a curing agent that is at least one selected from the group consisting of a metal chelate and an epoxy compound; A film, wherein the (meth)acrylic polymer contains a carboxy group-containing (meth)acrylic polymer. <3> The elongation of the underlayer is 90% or more when measured at 25°C and at a speed of 100 mm / min using a tensile test, and is calculated using the following formula: <2> The film according to claim 1. Elongation (%) = (elongation at break (mm)) x 100 / (distance between grips before tension (mm)) <4> The acid value of the underlayer is 1 to 80 mgKOH / g. <1> ~ <3> The film according to any one of claims 1 to 10. <5> the curing agent contains a metal chelate, and the amount of the metal chelate is 0.1 to 10 parts by mass per 100 parts by mass of the (meth)acrylic polymer; <1> ~ <4> The film according to any one of claims 1 to 10. <6> the curing agent contains an epoxy compound, and the amount of the epoxy compound is 0.1 to 10 parts by mass per 100 parts by mass of the (meth)acrylic polymer. <1> ~ <5> The film according to any one of claims 1 to 10. <7> The substrate comprises a fluororesin. <1> ~ <6> The film according to any one of claims 1 to 10. <8> the fluororesin comprises at least one selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, and a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer; <7> The film according to claim 1. <9> the substrate is corona-treated or plasma-treated; <1> ~ <8> The film according to any one of claims 1 to 10. <10> The adhesive layer contains a reaction cured product of a hydroxy group-containing (meth)acrylic polymer and a polyfunctional isocyanate compound. <1> ~ <9> The film according to any one of claims 1 to 10. <11> An antistatic layer is further provided between the base layer and the adhesive layer. <1> ~ <10> The film according to any one of claims 1 to 10. <12> This is a release film used in the process of sealing semiconductor elements with hardening resin. <1> ~ <11> The film according to any one of claims 1 to 10. <13> The aforementioned <1> ~ <12> Placing the film according to any one of the above on an inner surface of a mold; placing a substrate having a semiconductor element fixed thereto in the mold in which the film is placed; encapsulating the semiconductor element in the mold with a curable resin to produce an encapsulated body; Releasing the encapsulated body from the mold; A method for manufacturing a semiconductor package, comprising: [Effects of the Invention]

[0009] According to the present disclosure, there are provided a film that can prevent components of an adhesive layer from migrating to an encapsulant even when stretched, and a method for manufacturing a semiconductor package using the film. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows a schematic cross-sectional view of a film according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail, but the embodiments of the present disclosure are not limited to the following embodiments. In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these. In this disclosure, the term "unit" of a polymer refers to a portion derived from a monomer that exists in the polymer and constitutes the polymer. The term "unit" also refers to a unit obtained by chemically converting the structure of a unit after polymer formation. In some cases, units derived from individual monomers are referred to by the name of the monomer followed by "unit." In this disclosure, films and sheets are referred to as "films" regardless of their thickness. In this disclosure, acrylate and methacrylate are collectively referred to as "(meth)acrylate," and acrylic and methacrylic are collectively referred to as "(meth)acrylic." In the present disclosure, the film according to the first embodiment and the film according to the second embodiment may be collectively referred to as "the film of the present disclosure."

[0012] <Film> A film according to a first embodiment of the present disclosure is a film comprising a substrate, an underlayer, and an adhesive layer in this order, wherein the underlayer contains a cured product of a reaction between a (meth)acrylic polymer and a curing agent, and wherein the elongation of the underlayer is determined by the following formula in a tensile test at 25°C and a speed of 100 mm / min and is 90% or more: Elongation (%) = (elongation at break (mm)) x 100 / (distance between grips before tension (mm)) Hereinafter, the elongation measured by the above method will also be simply referred to as "elongation."

[0013] A film according to a second embodiment of the present disclosure is a film comprising a substrate, an underlayer, and an adhesive layer in this order, wherein the underlayer contains a reaction-cured product of a (meth)acrylic polymer and a curing agent that is at least one selected from the group consisting of a metal chelate and an epoxy compound, and the (meth)acrylic polymer contains a carboxy group-containing (meth)acrylic polymer.

[0014] It has been discovered that the film of the present disclosure can suppress the occurrence of adhesive residue, particularly when sealing elements in semiconductor packages having complex shapes. The inventors speculated that when a film is stretched during element sealing in a semiconductor package having a complex shape, the adhesive layer of the film cannot conform to the complex shape and cracks, resulting in the adhesive layer peeling off from the substrate and transferring to the sealing resin of the semiconductor package. Therefore, they attempted to create a film whose adhesive layer can conform to complex shapes and is therefore less likely to peel off from the substrate, leading to the development of the film of the present disclosure. The film according to the first embodiment has an underlayer between the substrate and the adhesive layer, the underlayer containing a cured product of a (meth)acrylic polymer and a curing agent, and the underlayer has an elongation rate of 90% or more. By providing an underlayer with an elongation rate of 90% or more between the substrate and the adhesive layer, it is believed that the propagation of stress due to the elongation of the substrate to the adhesive layer is alleviated, and cracking of the adhesive layer is suppressed. It is also believed that this makes the adhesive layer less likely to peel from the substrate and suppresses migration of components of the adhesive layer. A film according to a second embodiment has an underlayer between the substrate and the adhesive layer, and the underlayer comprises a reaction-cured product of a (meth)acrylic polymer containing a carboxyl group-containing (meth)acrylic polymer and at least one curing agent selected from the group consisting of a metal chelate and an epoxy compound. It is believed that using a metal chelate as a curing agent for the (meth)acrylic polymer results in a loose crosslinked structure formed by coordinate bonding between the carboxyl group in the (meth)acrylic polymer and the metal chelate, resulting in a highly extensible underlayer. It has also been found that a highly extensible underlayer can be obtained even when an epoxy compound is used as a curing agent. Providing such an underlayer between the substrate and the adhesive layer is believed to mitigate the transmission of stress caused by the extension of the substrate to the adhesive layer, thereby suppressing cracking of the adhesive layer. It is also believed that this makes the adhesive layer less likely to peel from the substrate and inhibits migration of the adhesive layer's components.

[0015] Hereinafter, examples of the film configuration will be described with reference to the drawings, but the film of the present disclosure is not limited to the embodiments shown in the drawings. 1 is a schematic cross-sectional view showing one embodiment of the film of the present disclosure. Film 1 comprises, in this order, a substrate 2, an underlayer 3, and an adhesive layer 4. When the film is used to encapsulate a semiconductor element, substrate 2 is disposed so as to contact a mold, and after resin encapsulation, adhesive layer 4 contacts the encapsulant (i.e., a semiconductor package in which a semiconductor element is encapsulated). Film 1 may also comprise other layers, such as an antistatic layer. Each layer of the film of the present disclosure is described in detail below.

[0016] <Base material> The material of the substrate is not particularly limited, and from the viewpoint of the releasability of the film, it is preferable that the substrate contains a resin having releasability (hereinafter also referred to as "releasable resin"). The releasable resin means a resin that has releasability when made only of the resin. Examples of releasable resins include fluororesin, polymethylpentene, syndiotactic polystyrene, polycycloolefin, silicone rubber, polyester elastomer, polybutylene terephthalate, and unstretched nylon. From the viewpoints of releasability from a mold, heat resistance at the mold temperature (e.g., 180°C) during sealing, strength capable of withstanding the flow and pressure of the curable resin, and elongation at high temperatures, fluororesin, polymethylpentene, syndiotactic polystyrene, and polycycloolefin are preferred, and from the viewpoint of excellent releasability, fluororesin is more preferred. The resin contained in the substrate may be used alone or in combination of two or more types. It is particularly preferable that the substrate consists solely of fluororesin.

[0017] As the fluororesin, a fluoroolefin polymer is preferred from the viewpoint of excellent mold releasability and heat resistance. The fluoroolefin polymer is a polymer having units based on a fluoroolefin. The fluoroolefin polymer may further have units other than the units based on a fluoroolefin. Examples of the fluoroolefin include tetrafluoroethylene (TFE), vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, etc. One type of fluoroolefin may be used alone, or two or more types may be used in combination.

[0018] Examples of the fluoroolefin polymer include ETFE, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), etc. One type of fluoroolefin polymer may be used alone, or two or more types may be used in combination.

[0019] As the fluoroolefin polymer, ETFE is preferred from the viewpoint of its high elongation at high temperatures. ETFE is a copolymer having TFE units and ethylene units (hereinafter also referred to as "E units"). As ETFE, a polymer having TFE units, E units, and units based on a third monomer other than TFE and ethylene is preferred. The crystallinity of ETFE can be easily adjusted by the type and content of the units based on the third monomer, which makes it easy to adjust the storage modulus or other tensile properties of the substrate. For example, when ETFE has units based on a third monomer (especially a monomer having a fluorine atom), the tensile strength and elongation at high temperatures (especially around 180°C) tend to be improved.

[0020] The third monomer includes a monomer having a fluorine atom and a monomer having no fluorine atom. Examples of the monomer having a fluorine atom include the following monomers (a1) to (a5). Monomer (a1): Fluoroolefins having 2 or 3 carbon atoms. Monomer (a2): X(CF2) n Fluoroalkylethylenes represented by CY=CH2 (wherein X and Y each independently represent a hydrogen atom or a fluorine atom, and n represents an integer of 2 to 8). Monomer (a3): Fluorovinyl ethers. Monomer (a4): Functional group-containing fluorovinyl ethers. Monomer (a5): A fluorine-containing monomer having an aliphatic ring structure.

[0021] Examples of the monomer (a1) include fluoroethylenes (trifluoroethylene, vinylidene fluoride, vinyl fluoride, chlorotrifluoroethylene, etc.), fluoropropylenes (hexafluoropropylene (HFP), 2-hydropentafluoropropylene, etc.), and the like.

[0022] As the monomer (a2), a monomer in which n is 2 to 6 is preferred, and a monomer in which n is 2 to 4 is more preferred. Also preferred is a monomer in which X is a fluorine atom and Y is a hydrogen atom, that is, (perfluoroalkyl)ethylene. Specific examples of the monomer (a2) include the following compounds: CF3CF2CH=CH2, CF3CF2CF2CF2CH=CH2((perfluorobutyl)ethylene (PFBE)), CF3CF2CF2CF2CF=CH2, CF2HCF2CF2CF=CH2, CF2HCF2CF2CF2CF=CH2 etc.

[0023] Specific examples of the monomer (a3) ​​include the following compounds: Among the following, diene monomers are cyclopolymerizable monomers. CF2 = CFOCF3, CF2 = CFOCF2CF3, CF2 = CFO(CF2)2CF3 (perfluoro(propyl vinyl ether) (PPVE)), CF2=CFOCF2CF(CF3)O(CF2)2CF3, CF2 = CFO(CF2)3O(CF2)2CF3, CF2=CFO(CF2CF(CF3)O)2(CF2)2CF3, CF2=CFOCF2CF(CF3)O(CF2)2CF3, CF2=CFOCF2CF=CF2, CF2 = CFO(CF2)2CF = CF2 etc.

[0024] Specific examples of the monomer (a4) include the following compounds: CF2 = CFO(CF2)3CO2CH3, CF2=CFOCF2CF(CF3)O(CF2)3CO2CH3, CF2=CFOCF2CF(CF3)O(CF2)2SO2F etc.

[0025] Specific examples of the monomer (a5) include perfluoro(2,2-dimethyl-1,3-dioxole), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, and perfluoro(2-methylene-4-methyl-1,3-dioxolane).

[0026] Examples of the monomer not having a fluorine atom include the following monomers (b1) to (b4). Monomer (b1): olefins, Monomer (b2): vinyl esters, Monomer (b3): ​​vinyl ethers, Monomer (b4): unsaturated acid anhydride.

[0027] Specific examples of the monomer (b1) include propylene and isobutene. Specific examples of the monomer (b2) include vinyl acetate. Specific examples of the monomer (b3) include ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, and hydroxybutyl vinyl ether. Specific examples of the monomer (b4) include maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride.

[0028] The third monomer may be used alone or in combination of two or more kinds. As the third monomer, from the viewpoint of easy adjustment of crystallinity and excellent tensile strength and elongation at high temperatures (particularly around 180°C), the monomer (a2), HFP, PPVE, and vinyl acetate are preferred, HFP, PPVE, CF3CF2CH=CH2, and PFBE are more preferred, and PFBE is even more preferred. That is, as ETFE, a copolymer having units based on TFE, units based on E, and units based on PFBE is preferred.

[0029] In ETFE, the molar ratio of TFE units to E units (TFE units / E units) is preferably 80 / 20 to 40 / 60, more preferably 70 / 30 to 45 / 55, and even more preferably 65 / 35 to 50 / 50. When the TFE units / E units is within the above range, the ETFE has excellent heat resistance and mechanical strength.

[0030] The proportion of units based on the third monomer in ETFE is preferably 0.01 to 20 mol %, more preferably 0.10 to 15 mol %, and even more preferably 0.20 to 10 mol %, relative to the total (100 mol %) of all units constituting ETFE. When the proportion of units based on the third monomer is within the above range, the ETFE has excellent heat resistance and mechanical strength.

[0031] When the units based on the third monomer include PFBE units, the proportion of the PFBE units is preferably 0.5 to 4.0 mol%, more preferably 0.7 to 3.6 mol%, and even more preferably 1.0 to 3.6 mol%, relative to the total (100 mol%) of all units constituting ETFE. When the proportion of the PFBE units is within the above range, the tensile modulus of the film at 180°C can be adjusted within the above range. Furthermore, the tensile strength and elongation at high temperatures, particularly around 180°C, are improved.

[0032] The substrate may consist solely of a release resin, or may further contain other components in addition to the release resin. Examples of other components include lubricants, antioxidants, antistatic agents, plasticizers, release agents, etc. From the viewpoint of preventing mold contamination, it is preferable that the substrate does not contain other components.

[0033] The thickness of the substrate is preferably 25 to 250 μm, more preferably 25 to 100 μm, and even more preferably 25 to 75 μm. When the thickness of the substrate is equal to or less than the upper limit of the above range, the film is easily deformable and has excellent mold conformability. When the thickness of the substrate is equal to or greater than the lower limit of the above range, the film is easy to handle, for example, in a roll-to-roll process, and wrinkles are less likely to occur when the film is stretched and placed to cover the cavity of a mold. The thickness of the substrate can be measured in accordance with ISO 4591:1992 (JIS K7130:1999) B1 method (a method for measuring thickness by the mass method of a sample taken from a plastic film or sheet). The same applies to the thickness of each layer of the film hereinafter.

[0034] The surface of the substrate may have surface roughness. The arithmetic mean roughness Ra of the substrate surface is preferably 0.2 to 3.0 μm, more preferably 0.2 to 2.5 μm. When the arithmetic mean roughness Ra of the substrate surface is equal to or greater than the lower limit of the above range, the releasability from the mold is better. In addition, blocking is less likely to occur between the substrate surface and the mold, and wrinkling due to blocking is less likely to occur. When the arithmetic mean roughness Ra of the substrate surface is equal to or less than the upper limit of the above range, pinholes are less likely to form in the film. The arithmetic mean roughness Ra is measured based on JIS B0601:2013 (ISO 4287:1997, Amd.1:2009). The reference length lr (cutoff value λc) for the roughness curve is 0.8 mm.

[0035] The surface of the substrate adjacent to other layers may be subjected to any surface treatment. Examples of surface treatment include corona treatment, plasma treatment, coating with a silane coupling agent, coating with an adhesive, etc. From the viewpoint of adhesion between the substrate and other layers, corona treatment or plasma treatment is preferred.

[0036] From the viewpoint of adhesion between the substrate and the adjacent layer, the wetting tension of the surface of the substrate on the undercoat layer side is preferably 20 mN / m or more, more preferably 30 mN / m or more, and particularly preferably 35 mN / m or more. The upper limit of the wetting tension is not particularly limited, and may be 80 mN / m or less.

[0037] The substrate may be a single layer or may have a multilayer structure. Examples of the multilayer structure include a structure in which multiple layers, each containing a release resin, are laminated. In this case, the release resins contained in the multiple layers may be the same or different. From the viewpoints of mold followability, tensile elongation, production costs, etc., the substrate is preferably a single layer. From the viewpoint of film strength, the substrate is preferably a multilayer structure. The multilayer structure may be, for example, a structure in which a layer containing the above-mentioned release resin (preferably a fluororesin) is laminated on a resin film (which may be a film containing only resin) containing a resin such as polyester, polybutylene terephthalate, polystyrene (preferably syndiotactic), or polycarbonate, or a structure in which a layer containing a first release resin, the resin film, and a layer containing a second release resin are laminated in this order. The layer containing the release resin and the resin film may be laminated via an adhesive. One or both sides of each release resin-containing layer may be subjected to corona treatment or plasma treatment. When the substrate has such a multilayer structure, it is preferable that the layer containing a release resin be disposed on the underlayer side.When the substrate has such a multilayer structure, it is preferable that the surface of the layer containing a release resin disposed on the underlayer side, on the underlayer side, has been subjected to a corona treatment or a plasma treatment.

[0038] <Underlayer> The underlayer contains a cured product obtained by reaction between a (meth)acrylic polymer and a curing agent, and is provided between the substrate and the adhesive layer.

[0039] The acid value of the underlayer is not particularly limited, but is preferably 1 to 80 mgKOH / g, more preferably 1 to 40 mgKOH / g, even more preferably 1 to 30 mgKOH / g, and particularly preferably 5 to 30 mgKOH / g. When the acid value is equal to or less than the upper limit of the above range, the underlayer has excellent extensibility. When the acid value is equal to or greater than the lower limit of the above range, the underlayer has excellent adhesion. The acid value of the underlayer is measured by the method specified in JIS K0070: 1992. The acid value of the underlayer can also be calculated using the following formula.

[0040] Acid value of the underlayer (mgKOHg / g) = ((total mass of the carboxyl group-containing (meth)acrylic polymer used) × its acid value) ÷ (total mass of the solid contents of the (meth)acrylic polymer, metal chelate, and additionally added materials used)

[0041] When multiple types of carboxyl group-containing (meth)acrylic polymers are used in the undercoat layer, the "acid value thereof" in the above formula is the arithmetic mean value of the acid values ​​of all of the multiple types of carboxyl group-containing (meth)acrylic polymers.

[0042] ((Meth)acrylic polymer) The (meth)acrylic polymer is a polymer having structural units derived from a monomer having a (meth)acryloyl group or (meth)acrylic acid (hereinafter, a monomer having a (meth)acryloyl group or (meth)acrylic acid will also be referred to as a "(meth)acrylic monomer"). The proportion of structural units derived from the (meth)acrylic monomer in the entire (meth)acrylic polymer is not particularly limited, and is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0043] The (meth)acrylic monomer that is a polymerization component of the (meth)acrylic polymer may be one type or two or more types. Examples of the (meth)acrylic monomer include (meth)acrylates that do not contain a hydroxy group or a carboxy group, hydroxy group-containing (meth)acrylates, carboxy group-containing (meth)acrylates, and (meth)acrylic acid. The (meth)acrylic polymer may be a polymer obtained by polymerizing any combination of these (meth)acrylic monomers.

[0044] Examples of (meth)acrylates that do not contain a hydroxy group or a carboxy group include alkyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, 3-(methacryloyloxypropyl)trimethoxysilane, trifluoromethylmethyl (meth)acrylate, and 2-trifluoromethylethyl (meth)acrylate. acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, and the like.

[0045] The alkyl (meth)acrylate is preferably a compound in which the alkyl group has 1 to 12 carbon atoms, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate.

[0046] Examples of hydroxy group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,4-cyclohexanedimethanol monoacrylate, and 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid.

[0047] Examples of the carboxy group-containing (meth)acrylate include ω-carboxy-polycaprolactone mono(meth)acrylate.

[0048] (Meth)acrylic acids include acrylic acid and methacrylic acid.

[0049] In one embodiment, the (meth)acrylic polymer preferably includes a carboxy-containing (meth)acrylic polymer. Examples of the carboxy-containing (meth)acrylic polymer include (meth)acrylic polymers having a carboxy-containing monomer as a constituent component, such as a (meth)acrylic polymer having a carboxy-containing (meth)acrylic monomer as a polymerization component. Examples of the carboxy-containing (meth)acrylic monomer include the above-mentioned carboxy-containing (meth)acrylate and (meth)acrylic acid. The carboxy-containing (meth)acrylic polymer may be composed solely of a carboxy-containing (meth)acrylic monomer as a constituent component, or may be a copolymer of a carboxy-containing (meth)acrylic monomer and another monomer.

[0050] The mass average molecular weight (Mw) of the (meth)acrylic polymer is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,000, and even more preferably 100,000 to 600,000. When Mw is at least the lower limit of the above range, the strength of the undercoat layer is excellent. When Mw is not more than the upper limit of the above range, the extensibility of the undercoat layer is excellent.

[0051] The Mw of the carboxy group-containing (meth)acrylic polymer is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,000, and even more preferably 100,000 to 600,000. When the Mw is at least the lower limit of the above range, the strength of the undercoat layer is excellent. When the Mw is at most the upper limit of the above range, the extensibility of the undercoat layer is excellent.

[0052] The Mw of the (meth)acrylic polymer is a polystyrene-equivalent value obtained by measuring by gel permeation chromatography using a calibration curve prepared using standard polystyrene samples of known molecular weight.

[0053] The acid value of the (meth)acrylic polymer is not particularly limited, and is preferably 1 to 80 mgKOH / g, more preferably 1 to 40 mgKOH / g, even more preferably 1 to 30 mgKOH / g, and particularly preferably 5 to 30 mgKOH / g. When the acid value is equal to or less than the upper limit of the above range, the underlayer has excellent extensibility. When the acid value is equal to or greater than the lower limit of the above range, the underlayer has excellent adhesion. When multiple types of (meth)acrylic polymers are used in the underlayer, the above range is the preferred range for the acid value of the entire multiple types of (meth)acrylic polymers.

[0054] The acid value of the carboxyl group-containing (meth)acrylic polymer is not particularly limited, but is preferably 1 to 80 mgKOH / g, more preferably 1 to 40 mgKOH / g, even more preferably 1 to 30 mgKOH / g, and particularly preferably 5 to 30 mgKOH / g. When the acid value is equal to or less than the upper limit of the above range, the undercoat layer has excellent extensibility. When the acid value is equal to or greater than the lower limit of the above range, the undercoat layer has excellent adhesion.

[0055] The acid value of the (meth)acrylic polymer is measured by the method specified in JIS K0070: 1992. The acid value of the (meth)acrylic polymer is an index of the ease of forming crosslinks when reacted with a curing agent.

[0056] (hardening agent) The curing agent is not particularly limited as long as it reacts with the (meth)acrylic polymer to cause curing, and examples of the curing agent include polyfunctional isocyanate compounds, metal chelates, and epoxy compounds.

[0057] Examples of the polyfunctional isocyanate compound include the polyfunctional isocyanate compounds described below as components of the adhesive layer.

[0058] In one embodiment, the curing agent may be at least one selected from the group consisting of a metal chelate and an epoxy compound. In one embodiment, the underlayer includes a reaction-cured product of a (meth)acrylic polymer and a curing agent including at least one selected from the group consisting of a metal chelate and an epoxy compound, and the (meth)acrylic polymer includes a carboxy group-containing (meth)acrylic polymer.

[0059] -Metal chelate- The metal chelate may be a compound in which a polyvalent metal atom and an organic compound are coordinately bonded. One type of metal chelate may be used alone, or two or more types may be used in combination. Examples of polyvalent metal atoms include Al, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, etc. From the viewpoints of low cost and easy availability, at least one selected from the group consisting of Al, Zr, and Ti is preferred, and Al is more preferred. Examples of organic compounds that form coordinate bonds with polyvalent metal atoms include organic compounds having oxygen atoms, such as alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

[0060] From the viewpoint of being relatively stable and easy to handle, the metal chelate is preferably an aluminum chelate, such as aluminum trisacetylacetonate.

[0061] When the curing agent contains a metal chelate, the amount of the metal chelate per 100 parts by mass of the (meth)acrylic polymer is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, even more preferably 1.0 to 10 parts by mass, and particularly preferably 2.5 to 10 parts by mass. When the amount of the metal chelate is equal to or less than the upper limit of the above range, peeling of the adhesive layer due to an increase in unreacted metal chelate can be suppressed. When the amount of the metal chelate is equal to or greater than the lower limit of the above range, peeling of the adhesive layer due to an increase in unreacted (meth)acrylic polymer can be suppressed.

[0062] When the curing agent contains a metal chelate and is used in combination with a carboxy group-containing (meth)acrylic polymer, the amount of the metal chelate per 100 parts by mass of the carboxy group-containing (meth)acrylic polymer is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, even more preferably 1.0 to 10 parts by mass, and particularly preferably 2.5 to 10 parts by mass. When the amount of the metal chelate is equal to or less than the upper limit of the above range, peeling of the adhesive layer due to an increase in unreacted metal chelate can be suppressed. When the amount of the metal chelate is equal to or greater than the lower limit of the above range, peeling of the adhesive layer due to an increase in unreacted carboxy group-containing (meth)acrylic polymer can be suppressed.

[0063] -Epoxy compounds- The epoxy compound may be a compound having two or more epoxy groups in one molecule, preferably two or more, and more preferably two to six epoxy groups.

[0064] Examples of the epoxy compound include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, resorcinol diglycidyl ether, glycerol polyglycidyl ether, etc. One type of epoxy compound may be used alone, or two or more types may be used in combination.

[0065] Commercially available epoxy compounds may be used, such as TETRAD-X (trade name) and TETRAD-C (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc., and Denacol (registered trademark) EX-201 (trade name) and Denacol (registered trademark) EX-313 (trade name) manufactured by Nagase ChemteX Corporation.

[0066] From the viewpoint of obtaining high extensibility without excessively increasing the crosslink density, the epoxy equivalent of the epoxy compound is preferably 300 g / eq or less, more preferably 200 g / eq or less, even more preferably 150 g / eq or less, and particularly preferably 120 g / eq or less. From the viewpoint of increasing the strength of the undercoat layer, the epoxy equivalent of the epoxy compound is preferably 30 g / eq or more, more preferably 50 g / eq or more, and even more preferably 90 g / eq or more. From such viewpoints, the epoxy equivalent of the epoxy compound is preferably 30 to 300 g / eq, more preferably 50 to 200 g / eq, and even more preferably 90 to 120 g / eq.

[0067] When the curing agent contains an epoxy compound, the amount of the epoxy compound per 100 parts by mass of the (meth)acrylic polymer is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, even more preferably 1.0 to 10 parts by mass, and particularly preferably 2.5 to 10 parts by mass. When the amount of the epoxy compound is equal to or less than the upper limit of the above range, peeling of the adhesive layer due to an increase in unreacted epoxy compound can be suppressed. When the amount of the epoxy compound is equal to or greater than the lower limit of the above range, peeling of the adhesive layer due to an increase in unreacted (meth)acrylic polymer can be suppressed.

[0068] When the curing agent contains an epoxy compound and is used in combination with a carboxy group-containing (meth)acrylic polymer, the amount of the epoxy compound per 100 parts by mass of the (meth)acrylic polymer is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 10 parts by mass, even more preferably 1.0 to 10 parts by mass, and particularly preferably 2.5 to 10 parts by mass. When the amount of the epoxy compound is equal to or less than the upper limit of the above range, peeling of the adhesive layer due to an increase in unreacted epoxy compound can be suppressed. When the amount of the epoxy compound is equal to or greater than the lower limit of the above range, peeling of the adhesive layer due to an increase in unreacted carboxy group-containing (meth)acrylic polymer can be suppressed.

[0069] [Base layer thickness] The thickness of the underlayer is preferably 0.1 to 3.0 μm, more preferably 0.2 to 2.5 μm, and even more preferably 0.3 to 2.0 μm. When the thickness of the underlayer is at least the lower limit of the above range, stress relaxation against elongation of the substrate is excellent. When the thickness of the underlayer is not more than the upper limit of the above range, coating stability of the adhesive layer is excellent.

[0070] [Base layer elongation rate] The elongation of the underlayer is preferably 90% or more, more preferably 100% or more, even more preferably 150% or more, particularly preferably 200% or more, and extremely preferably 300% or more. There is no particular upper limit to the elongation, and the elongation may be 600% or less, or may be 500% or less. The elongation of the underlayer is measured under the following conditions. A tensile test is carried out at 25°C and a speed of 100 mm / min, and the elongation is calculated using the following formula. Elongation (%) = (elongation at break (mm)) x 100 / (distance between grips before tension (mm)) Specifically, the elongation is measured by the method described in the examples.

[0071] The method for adjusting the elongation percentage of the underlayer is not particularly limited, and can be done by adjusting the type and blending of the components of the underlayer, etc. For example, the elongation percentage can be adjusted to 90% or more by blending the components of the underlayer so as to reduce the crosslink density, or by selecting the components of the underlayer so as to have a gentle crosslinking structure.

[0072] <Adhesive layer> The adhesive layer is a layer that has adhesiveness to other members. The material of the adhesive layer is not particularly limited. In one embodiment, the adhesive layer may contain a reaction-cured product of a hydroxy group-containing (meth)acrylic polymer and a polyfunctional isocyanate compound. In this case, the hydroxy group-containing (meth)acrylic polymer reacts with the polyfunctional isocyanate compound to crosslink and become a reaction-cured product. The adhesive layer may also be a reaction-cured product of a hydroxy group-containing (meth)acrylic polymer, a polyfunctional isocyanate compound, and other components.

[0073] (Hydroxy group-containing (meth)acrylic polymer) The hydroxy group contained in the hydroxy group-containing (meth)acrylic polymer is a crosslinking functional group that reacts with the isocyanate group in the polyfunctional isocyanate compound. The hydroxyl value of the hydroxy group-containing (meth)acrylic polymer is preferably from 1 to 100 mgKOH / g, more preferably from 29 to 100 mgKOH / g. The hydroxyl value is measured by the method specified in JIS K0070:1992.

[0074] The hydroxyl group-containing (meth)acrylic polymer may or may not have a carboxyl group. The carboxyl group, like the hydroxyl group, is a crosslinking functional group that reacts with the isocyanate group in the polyfunctional isocyanate compound. The acid value of the hydroxy group-containing (meth)acrylic polymer is preferably 0 to 100 mgKOH / g, more preferably 0 to 30 mgKOH / g. The acid value is measured by the method specified in JIS K0070:1992, similar to the hydroxy value.

[0075] The crosslinkable functional group equivalent of the hydroxy group-containing (meth)acrylic polymer, ie, the total equivalent of the hydroxy group and the carboxy group, is preferably 2,000 g / mol or less, more preferably 500 to 2,000 g / mol, and even more preferably 1,000 to 2,000 g / mol. The crosslinking functional group equivalent corresponds to the molecular weight between crosslinking points and is a physical property that governs the elastic modulus after crosslinking, i.e., the elastic modulus of the reaction-cured product. When the crosslinking functional group equivalent is equal to or less than the upper limit of the above range, the elastic modulus of the reaction-cured product is high, and the adhesive layer has excellent releasability against resins, electronic components, etc. In addition, migration of the components of the adhesive layer to resins, electronic components, etc. is suppressed.

[0076] In the hydroxy group-containing (meth)acrylic polymer, the hydroxy group may be present in a side group, at the end of the main chain, or both in the side chain and the main chain. From the viewpoint of facilitating adjustment of the hydroxy group content, it is preferable that the hydroxy group be present at least in the side group.

[0077] The hydroxy group-containing (meth)acrylic polymer in which the hydroxy group exists in the side group is preferably a copolymer having the following units (c1) and (c2). Unit (c1): hydroxy group-containing (meth)acrylate unit Unit (c2): Unit other than Unit (c1)

[0078] Examples of the unit (c1) include the following units: -(CH2-CR 1 (COO-R 2 -OH))-

[0079] In unit (c1), R 1 is a hydrogen atom or a methyl group, and R 2 represents an alkylene group having 2 to 10 carbon atoms, a cycloalkylene group having 3 to 10 carbon atoms, or -R 3 -OCO-R 5 -COO-R 4 -R 3 and R 4 are each independently an alkylene group having 2 to 10 carbon atoms, and R 5 is a phenylene group. R 1 is preferably a hydrogen atom. R 2 , R 3 , R 4 The alkylene group in may be linear or branched.

[0080] Specific examples of the monomer that forms the unit (c1) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,4-cyclohexanedimethanol monoacrylate, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, etc. The monomer that forms the unit (c1) may be used alone or in combination of two or more. As the unit (c1), from the viewpoint of excellent reactivity of the hydroxy group, R 2is preferably an alkylene group having 2 to 10 carbon atoms. That is, a hydroxyalkyl (meth)acrylate unit having a hydroxyalkyl group having 2 to 10 carbon atoms is preferred.

[0081] The proportion of units (c1) relative to the total (100 mol%) of all units constituting the hydroxy group-containing (meth)acrylic polymer is preferably 3 to 30 mol%, more preferably 3 to 20 mol%. When the proportion of units (c1) is at least the lower limit of the above range, the crosslinking density by the polyfunctional isocyanate compound becomes sufficiently high, and the adhesive layer has excellent releasability against resins, electronic components, etc. When the proportion of units (c1) is at most the upper limit of the above range, the adhesive layer has excellent adhesion.

[0082] The unit (c2) is not particularly limited as long as it is copolymerizable with the monomer that forms the unit (c1). The unit (c2) may have a carboxy group, but preferably does not have a reactive group other than the carboxy group (e.g., an amino group) that can react with an isocyanate group. Examples of monomers that form unit (c2) include (meth)acrylates without a hydroxy group, (meth)acrylic acid, acrylonitrile, macromers with an unsaturated double bond, etc. Examples of macromers with an unsaturated double bond include macromers with a polyoxyalkylene chain, such as (meth)acrylates of polyethylene glycol monoalkyl ether. Examples of (meth)acrylates that do not have a hydroxy group include alkyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, 3-(methacryloyloxypropyl)trimethoxysilane, trifluoromethylmethyl (meth)acrylate, and 2-trifluoromethylethyl (meth)acrylate. perfluoromethylmethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, and the like.

[0083] The alkyl (meth)acrylate is preferably a compound in which the alkyl group has 1 to 12 carbon atoms, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate.

[0084] The unit (c2) preferably contains at least an alkyl (meth)acrylate unit. The proportion of alkyl (meth)acrylate units relative to the total (100 mol%) of all units constituting the hydroxy group-containing (meth)acrylic polymer is preferably 60 to 97 mol%, more preferably 70 to 97 mol%, and even more preferably 80 to 97 mol%. When the proportion of alkyl (meth)acrylate units is at or above the lower limit of the above range, the glass transition temperature, mechanical properties, etc., derived from the alkyl (meth)acrylate structure are exhibited, resulting in excellent mechanical strength and adhesiveness of the adhesive layer. When the proportion of alkyl acrylate units is at or below the upper limit of the above range, the hydroxy group content is sufficient, resulting in increased crosslinking density and a high elastic modulus.

[0085] The Mw of the hydroxy group-containing (meth)acrylic polymer is preferably 100,000 to 1,200,000, more preferably 200,000 to 1,000,000, and even more preferably 200,000 to 700,000. When the Mw is at least the lower limit of the above range, the adhesive layer has excellent releasability from resins, electronic components, etc. When the Mw is at most the upper limit of the above range, the adhesive layer has excellent adhesion. The Mw of the hydroxy group-containing (meth)acrylic polymer is a polystyrene-equivalent value obtained by measuring by gel permeation chromatography using a calibration curve prepared using standard polystyrene samples of known molecular weight.

[0086] The glass transition temperature (Tg) of the hydroxy group-containing (meth)acrylic polymer is preferably 20° C. or lower, more preferably 0° C. or lower. When Tg is equal to or higher than the lower limit of the above range, the adhesive layer exhibits sufficient flexibility even at low temperatures, and is less likely to peel from the substrate. The lower limit of Tg is not particularly limited, but is preferably −60° C. or higher within the above-mentioned molecular weight range. Tg means the midpoint glass transition temperature as measured by differential scanning calorimetry (DSC).

[0087] (Polyfunctional isocyanate compounds) The polyfunctional isocyanate compound is a compound having two or more isocyanate groups, and preferably a compound having 3 to 10 isocyanate groups. Examples of polyfunctional isocyanate compounds include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), triphenylmethane triisocyanate, tris(isocyanatophenyl)thiophosphate, etc. Further examples include isocyanurate (trimer) and biuret of these polyfunctional isocyanate compounds, and adducts of these polyfunctional isocyanate compounds with polyol compounds.

[0088] The polyfunctional isocyanate compound preferably has an isocyanurate ring, since the planarity of the ring structure allows the reaction-cured product (adhesive layer) to exhibit a high modulus of elasticity. Examples of polyfunctional isocyanate compounds having an isocyanurate ring include isocyanurate forms of HDI (isocyanurate-type HDI), isocyanurate forms of TDI (isocyanurate-type TDI), and isocyanurate forms of MDI (isocyanurate-type MDI).

[0089] (Other ingredients) Other components used in the adhesive layer include crosslinking catalysts (amines, metal compounds, acids, etc.), reinforcing fillers, coloring dyes, pigments, antistatic agents, and the like.

[0090] The crosslinking catalyst may be any substance that functions as a catalyst for the reaction (urethanization reaction) between the hydroxyl group-containing acrylic copolymer and the crosslinking agent when a polyfunctional isocyanate compound is used as the crosslinking agent, and a general urethanization reaction catalyst can be used. Examples of crosslinking catalysts include amine compounds such as tertiary amines, organotin compounds, organolead compounds, and organozinc compounds, among other organometallic compounds. Examples of tertiary amines include trialkylamines, N,N,N',N'-tetraalkyldiamines, N,N-dialkylaminoalcohols, triethylenediamine, morpholine derivatives, and piperazine derivatives. Examples of organotin compounds include dialkyltin oxides, fatty acid salts of dialkyltins, and fatty acid salts of stannous. As the crosslinking catalyst, an organic tin compound is preferred, and dioctyltin oxide, dioctyltin dilaurate, dibutyltin laurate, and dibutyltin dilaurate are more preferred. Also usable is a dialkylacetylacetone tin complex catalyst, which is synthesized by reacting a dialkyltin ester with acetylacetone in a solvent and has a structure in which two acetylacetone molecules are coordinated to one dialkyltin atom. The amount of the crosslinking catalyst used is preferably 0.01 to 0.5 parts by mass per 100 parts by mass of the hydroxy group-containing (meth)acrylic polymer.

[0091] Examples of the antistatic agent include ionic liquids, conductive polymers, metal ion conductive salts, and conductive metal oxides. Conductive polymers are polymers in which electrons move and diffuse along the polymer backbone, and examples of conductive polymers include polyaniline polymers, polyacetylene polymers, polyparaphenylene polymers, polypyrrole polymers, polythiophene polymers, and polyvinylcarbazole polymers. Examples of metal ion conductive salts include lithium salt compounds. Examples of conductive metal oxides include tin oxide, tin-doped indium oxide, antimony-doped tin oxide, phosphorus-doped tin oxide, zinc antimonate, and antimony oxide. The amount of the antistatic agent used is appropriately determined depending on the desired surface resistance value of the adhesive layer.

[0092] The total content of the hydroxy group-containing (meth)acrylic polymer and the polyfunctional isocyanate compound in the adhesive layer composition used to form the adhesive layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total amount of the adhesive layer composition. Note that the adhesive layer composition does not contain a liquid medium.

[0093] [Adhesive layer thickness] The thickness of the adhesive layer is preferably 0.05 to 3.0 μm, more preferably 0.05 to 2.5 μm, and even more preferably 0.05 to 2.0 μm. When the thickness of the adhesive layer is at least the lower limit of the above range, excellent releasability is achieved. When the thickness of the adhesive layer is at most the upper limit of the above range, excellent coating stability is achieved. Furthermore, when the thickness of the adhesive layer is at most the upper limit of the above range, tackiness after coating is not too strong, facilitating a continuous coating process.

[0094] <Other layers> The film may or may not have layers other than the substrate, underlayer, and adhesive layer. Examples of such layers include a gas barrier layer, an antistatic layer, and a colored layer. These layers may be used alone or in combination of two or more.

[0095] In order to effectively prevent damage to semiconductor elements, etc. due to discharge during peeling, it is preferable to have an antistatic layer between the substrate and the underlayer or between the underlayer and the adhesive layer. That is, the film may have the substrate, antistatic layer, underlayer, and adhesive layer in this order, or the substrate, underlayer, antistatic layer, and adhesive layer in this order. The antistatic layer is a layer containing an antistatic agent, and examples of the antistatic agent include the same as those described above. In the antistatic layer, the antistatic agent is preferably dispersed in a resin binder. The resin binder is preferably heat-resistant enough to withstand the heat (e.g., 180°C) in the sealing process, and examples thereof include acrylic resin, silicone resin, urethane resin, polyester resin, polyamide resin, vinyl acetate resin, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, chlorotrifluoroethylene-vinyl alcohol copolymer, and tetrafluoroethylene-vinyl alcohol copolymer. The resin binder may be cross-linked, which provides better heat resistance than a non-cross-linked resin binder. The thickness of the antistatic layer is preferably 0.05 to 3.0 μm, more preferably 0.1 to 2.5 μm. When the thickness of the antistatic layer is at least the lower limit of the above range, electrical conductivity is exhibited and the antistatic function is excellent. When the thickness of the antistatic layer is not more than the upper limit of the above range, the stability of the appearance of the coated surface and the stability of the production process are excellent. The surface resistance of the antistatic layer is 10 10 Ω / □ or less is preferable, and 10 9 Ω / □ or less is more preferable.

[0096] [Film manufacturing method] The film is produced, for example, by the following method. A coating liquid for an underlayer, which contains a composition for an underlayer containing a (meth)acrylic polymer and a curing agent, and a liquid medium, is applied to one surface of a substrate and dried to form an underlayer. A coating liquid for an adhesive layer, which contains a composition for an adhesive layer and a liquid medium, is applied to the surface of the formed underlayer opposite the substrate and dried to form an adhesive layer. After forming the underlayer, an antistatic layer may be formed, and then an adhesive layer may be formed. Other optional layers may also be formed. Heat may be applied to promote curing during the formation of each layer.

[0097] [Film characteristics] (surface resistance value) The surface resistance of the film is not particularly limited, and is 10 17 It may be Ω / □ or less, and 10 11 Ω / □ or less is preferable, and 1010 Ω / □ or less is more preferable, and 10 9 The surface resistivity is more preferably Ω / □ or less. There is no particular lower limit to the surface resistivity. The surface resistance of the film is measured in accordance with IEC 60093:1980: double ring electrode method, at an applied voltage of 500 V for 1 minute. As a measuring device, for example, an ultra-high resistance meter R8340 (Advantec) can be used.

[0098] [Film uses] The film of the present disclosure is useful, for example, as a release film used in a process for encapsulating a semiconductor element with a curable resin, and is particularly useful as a release film used in a process for producing a semiconductor package having a complex shape, for example, an encapsulated body in which a portion of an electronic component is exposed from the resin.

[0099] <Semiconductor package manufacturing method> In one aspect, a method for manufacturing a semiconductor package includes: placing a film of the present disclosure on an interior surface of a mold; placing a substrate having a semiconductor element fixed thereto in the mold in which the film is placed; encapsulating the semiconductor element in the mold with a curable resin to produce an encapsulated body; Releasing the encapsulated body from the mold; Includes.

[0100] Examples of semiconductor packages include integrated circuits in which semiconductor elements such as transistors and diodes are integrated; and light-emitting diodes having light-emitting elements. The package shape of an integrated circuit may be one that covers the entire integrated circuit or one that covers only a portion of the integrated circuit, i.e., one that exposes a portion of the integrated circuit. Specific examples include BGA (Ball Grid Array), QFN (Quad Flat Non-leaded package), and SON (Small Outline Non-leaded package). From the viewpoint of productivity, semiconductor packages are preferably manufactured through collective sealing and singulation, and examples thereof include integrated circuits sealed by the MAP (Molded Array Packaging) method or the WL (Wafer Level Packaging) method.

[0101] As the curable resin, a thermosetting resin such as an epoxy resin or a silicone resin is preferred, and an epoxy resin is more preferred.

[0102] In one embodiment, the semiconductor package may or may not include electronic components such as a source electrode and a seal glass in addition to the semiconductor element. Also, some of the electronic components such as the semiconductor element, source electrode, and seal glass may be exposed from the resin.

[0103] The semiconductor package manufacturing method can be a known manufacturing method except for using the film of the present disclosure. For example, a transfer molding method can be used as a method for encapsulating a semiconductor element, and a known transfer molding device can be used as the device used in this method. The manufacturing conditions can also be the same as those in known semiconductor package manufacturing methods. [Example]

[0104] Next, embodiments of the present disclosure will be described in detail using examples, but the embodiments of the present disclosure are not limited to these examples. In the following examples, Examples 1 to 9 and 13 to 17 are working examples, and Examples 10 to 12 are comparative examples.

[0105] The materials used to form each layer are as follows:

[0106] <Base material> ETFE film 1: Fluon (registered trademark) ETFE C-88AXP (AGC) was fed into an extruder equipped with a T-die and taken up between a pressure roll with an uneven surface and a mirror-finished metal roll to produce a film with a thickness of 50 μm. The temperatures of the extruder and T-die were 320°C, and the temperatures of the pressure roll and metal roll were 100°C. The surface Ra of the obtained film was 2.0 μm on the pressure roll side and 0.2 μm on the mirror-finished side. ETFE film 2: Corona treatment was applied to the mirror side of ETFE film 1. The wetting tension of the corona-treated surface based on ISO8296:1987 (JIS K6768:1999) was 50 mN / m. ETFE film 3: A high-frequency voltage of 110 kHz was applied to both sides of ETFE film 1 under an argon atmosphere at a pressure of 0.2 Torr, with a discharge power density of 300 Wmin / m. 2 The plasma treatment was performed at 1000 W. The wetting tension of the plasma-treated surface was 58 mN / m based on ISO8296:1987 (JIS K6768:1999). ETFE film 4: Fluon (registered trademark) ETFE C-88AXP (manufactured by AGC) was fed into an extruder equipped with a T-die and taken up between a smooth pressing roll and a mirror-finished metal roll to produce a film with a thickness of 12 μm. The temperatures of the extruder and T-die were 320°C, and the temperatures of the pressing roll and metal roll were 100°C. The Ra of the surface of the obtained film was 0.2 μm on the pressing roll side and 0.2 μm on the mirror-finished side. Corona treatment was applied to both sides of the obtained film. The wetting tension of the corona-treated side according to ISO 8296:1987 (JIS K6768:1999) was 50 mN / m. ETFE film 5: The same procedure as for ETFE film 4 was repeated except that the mirror surface side of the obtained film was subjected to corona treatment, and the pressing roll side was not subjected to corona treatment. ETFE film 6: Obtained in the same manner as ETFE film 1, except that the thickness was changed to 25 μm. The Ra of the surface of the obtained film was 2.0 μm on the pressing roll side and 0.2 μm on the mirror side.

[0107] Laminate 1: An ETFE film 4 was bonded to one surface of a 12 μm thick polyester film (Ester (registered trademark) NSCW manufactured by Toyobo Co., Ltd.) via an adhesive (CRISVON (registered trademark) NT-258 manufactured by DIC Corporation: Coronate (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1 (mass ratio)). Next, the mirror side of an ETFE film 5 was bonded to the other surface of the polyester film via an adhesive (CRISVON (registered trademark) NT-258 manufactured by DIC Corporation: Coronate (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1). Laminate 2: An ETFE film 4 was bonded to one surface of a 25 μm thick polyester film (Tetoron GEC manufactured by Toyobo Co., Ltd.) via an adhesive (CRISVON (registered trademark) NT-258 manufactured by DIC Corporation: CORONATE (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1 (mass ratio)). Next, the mirror side of an ETFE film 5 was bonded to the other surface of the polyester film via an adhesive (CRISVON (registered trademark) NT-258 manufactured by DIC Corporation: CORONATE (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1 (mass ratio)). Laminate 3: An ETFE film 4 was bonded to one surface of a 38 μm thick polyester film (Tetoron GEC manufactured by Toyobo Co., Ltd.) via an adhesive (Crisvon (registered trademark) NT-258 manufactured by DIC Corporation: Coronate (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1). Laminate 4: An ETFE film 4 was bonded to one surface of a 75 μm thick polyester film (Teijin Tetron HS74 manufactured by DuPont Hongji Films Foshan) via an adhesive (Crisvon (registered trademark) NT-258 manufactured by DIC: Coronate (registered trademark) 2096 manufactured by Tosoh = 16:1). Laminate 5: An ETFE film 4 was bonded to one surface of a 12 μm thick polyester film (Ester (registered trademark) NSCW manufactured by Toyobo Co., Ltd.) via an adhesive (CRISVON (registered trademark) NT-258 manufactured by DIC Corporation: CORONATE (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1 (mass ratio)). Next, the mirror side of an ETFE film 6 was bonded to the other surface of the polyester film via an adhesive (CRISVON (registered trademark) NT-258 manufactured by DIC Corporation: CORONATE (registered trademark) 2096 manufactured by Tosoh Corporation = 16:1 (mass ratio)).

[0108] <Coating liquid for undercoat layer> [(Meth)acrylic polymer] (Meth)acrylic polymer 1: The following (meth)acrylic monomers 1 to 3 were mixed and polymerized to give an acid value of 18.7 mg KOH / g and an Mw of 150,000, to obtain (meth)acrylic polymer 1. (Meth)acrylic monomer 1: methyl methacrylate (Meth)acrylic monomer 2: 2-ethylhexyl acrylate (Meth)acrylic monomer 3: acrylic acid

[0109] [Metal chelates] Metal chelate 1: Aluminum trisacetylacetonate (trade name: Aluminum Chelate A, manufactured by Kawaken Fine Chemicals Co., Ltd.)

[0110] [Epoxy Compound] Epoxy compound 1: TETRAD-X (trade name, manufactured by Mitsubishi Gas Chemical Company, Inc., N,N,N',N'-tetraglycidyl-m-xylylenediamine, epoxy equivalent 95-110 g / eq)

[0111] <Coating liquid for antistatic layer> Antistatic agent-containing material 1: Aracoat (registered trademark) AS601D (manufactured by Arakawa Chemical Industries, Ltd.), solid content 3.4% by mass, conductive polythiophene 0.4% by mass, acrylic resin 3.0% by mass Curing agent 1: Araquat (registered trademark) CL910 (manufactured by Arakawa Chemical Industries, Ltd.), solid content 10% by mass, polyfunctional aziridine compound

[0112] <Coating liquid for adhesive layer> (Meth)acrylic polymer 2 diluted solution: Nissetsu (registered trademark) KP2562 (manufactured by Nippon Carbide Industries Co., Ltd.), solid content 35%. (Meth)acrylic polymer 2 contains hydroxy groups but does not contain carboxy groups. Polyfunctional isocyanate compound 1: Nissetsu CK157 (manufactured by Nippon Carbide Industries Co., Ltd.), solid content 100%, isocyanurate-type hexamentylene diisocyanate, NCO content 21% by mass

[0113] <Example 1> [Preparation of Underlayer] (Meth)acrylic polymer 1 was diluted with ethyl acetate to obtain a diluted (meth)acrylic polymer 1 solution with a solid content of 45% by mass. Metal chelate 1 was diluted with toluene and acetylacetone to a solid content of 7% by mass to obtain a diluted solution of Metal chelate 1. 100 parts by mass of diluted (meth)acrylic polymer 1, 37 parts by mass of diluted metal chelate 1, and 150 parts by mass of ethyl acetate as a dilution solvent were mixed to prepare a coating liquid for undercoat layer with a solid content of 14% by mass.

[0114] The primer layer coating solution was applied to the corona-treated mirror surface of ETFE film 2 using a gravure coater and dried to form a 0.8 μm thick primer layer. Coating was performed using a direct gravure method, using a Φ100 mm x 250 mm wide roll with a 150mm grid and a depth of 40 μm as the gravure plate. Drying was performed at 100°C for 1 minute, passing through a roll-supported drying oven with an air flow of 19 m / s. The film was then cured at 40°C for 120 hours to obtain the primer layer.

[0115] The acid value of the underlayer at this time was 17.7 mgKOH / g. The acid value of the underlayer was calculated using the following formula: The acid values ​​of the other examples were calculated in the same manner.

[0116] Acid value of the underlayer (mgKOH / g) = ((total mass of the carboxyl group-containing (meth)acrylic polymer used) × its acid value) ÷ (total mass of the solid contents of the (meth)acrylic polymer, metal chelate, and additionally added materials used)

[0117] The metal chelate content in the underlayer was 5.8 parts by mass per 100 parts by mass of the (meth)acrylic polymer. The metal chelate content was calculated using the following formula. The metal chelate contents of the other examples were also calculated in the same manner.

[0118] Metal chelate content (parts by mass) = mass of metal chelate solids in coating liquid / (total mass of (meth)acrylic polymers 1 and 2 in coating liquid) × 100

[0119] [Preparation of adhesive layer] A coating liquid for adhesive layer was prepared by mixing 100 parts by mass of the diluted solution of (meth)acrylic polymer 2, 6 parts by mass of polyfunctional isocyanate compound 1, and ethyl acetate. The amount of ethyl acetate added was such that the solid content of the coating liquid for adhesive layer became 14% by mass. The adhesive layer coating solution was applied to the surface of the base layer using a gravure coater and dried to form a 0.8 μm thick adhesive layer. Coating was performed using a direct gravure method, using a Φ100 mm x 250 mm wide, 150# grid, 40 μm deep roll as the gravure plate. Drying was performed at 100°C for 1 minute through a roll-supported drying oven with an airflow of 19 m / s. The film was then aged at 40°C for 120 hours to obtain a film.

[0120] <Example 2> A film was obtained in the same manner as in Example 1, except that an antistatic layer was formed on the underlayer of Example 1. The antistatic layer was formed as follows. [Preparation of Antistatic Layer] A coating solution for the antistatic layer with a solids content of 2% by mass was prepared by mixing 100 parts by mass of antistatic agent-containing material 1 and 10 parts by mass of curing agent 1. The coating solution for the antistatic layer was applied to the surface of the base layer using a gravure coater and dried to form an antistatic layer with a thickness of 0.2 μm. Coating was performed using a direct gravure method, using a Φ100 mm x 250 mm wide, 150mm grid, 40 μm deep roll as the gravure plate. Drying was performed at 100°C for 1 minute, passing through a roll-supported drying oven with an airflow of 19 m / s.

[0121] <Example 3> A coating liquid for an undercoat layer was prepared by mixing the same coating liquid for an adhesive layer as in Example 1 and the same coating liquid for an undercoat layer as in Example 1 in a mass ratio of 2:8. A film was obtained in the same manner as in Example 2, except that the undercoat layer was prepared using this coating liquid for an undercoat layer.

[0122] <Example 4> A film was obtained in the same manner as in Example 2, except that ETFE film 3 was used as the substrate instead of ETFE film 2. The underlayer was formed on the mirror side surface of ETFE film 3.

[0123] <Example 5> A coating liquid for an undercoat layer was prepared by mixing the same coating liquid for an adhesive layer as in Example 1 and the same coating liquid for an undercoat layer as in Example 1 in a mass ratio of 5:5. A film was obtained in the same manner as in Example 2, except that the undercoat layer was prepared using this coating liquid for an undercoat layer.

[0124] <Example 6> A film was obtained in the same manner as in Example 2, except that a diluted solution of epoxy compound 1 with a solid content of 7 mass % obtained by diluting epoxy compound 1 with ethyl acetate and isopropyl alcohol was used instead of the diluted solution of metal chelate 1 as the curing agent for the undercoat layer.

[0125] <Example 7> A film was obtained in the same manner as in Example 6, except that ETFE film 3 was used as the substrate instead of ETFE film 2. The underlayer was formed on the mirror side surface of ETFE film 3.

[0126] <Example 8> A film was obtained in the same manner as in Example 2, except that the thickness of the adhesive layer was changed to 0.1 μm.

[0127] <Example 9> A coating liquid for an undercoat layer was prepared by mixing the same coating liquid for an adhesive layer as in Example 1 and the same coating liquid for an undercoat layer as in Example 1 in a mass ratio of 9:1. A film was obtained in the same manner as in Example 2, except that the undercoat layer was prepared using this coating liquid for an undercoat layer.

[0128] <Example 10> A film was obtained in the same manner as in Example 2, except that the same adhesive layer coating liquid as in Example 1 was used as the underlayer coating liquid to form the underlayer.

[0129] <Example 11> A film was obtained in the same manner as in Example 2, except that no undercoat layer was provided.

[0130] <Example 12> A film was obtained in the same manner as in Example 2, except that the undercoat layer and adhesive layer were not provided.

[0131] <Example 13> A film was obtained in the same manner as in Example 2, except that the laminate 1 was used as the substrate instead of the ETFE film 2. The underlayer was formed on the surface of the ETFE film 4 opposite to the polyester film.

[0132] <Example 14> A film was obtained in the same manner as in Example 2, except that Laminate 2 was used as the substrate instead of ETFE film 2. The underlayer was formed on the surface of ETFE film 4 opposite to the polyester film.

[0133] <Example 15> A film was obtained in the same manner as in Example 2, except that the laminate 3 was used as the substrate instead of the ETFE film 2. The underlayer was formed on the surface of the ETFE film 4 opposite to the polyester film.

[0134] <Example 16> A film was obtained in the same manner as in Example 2, except that the laminate 4 was used as the substrate instead of the ETFE film 2. The underlayer was formed on the surface of the ETFE film 4 opposite to the polyester film.

[0135] <Example 17> A film was obtained in the same manner as in Example 2, except that the laminate 5 was used as the substrate instead of the ETFE film 2. The underlayer was formed on the surface of the ETFE film 4 opposite to the polyester film.

[0136] 〔evaluation〕 (Thickness) The thicknesses (μm) of the substrate, undercoat layer, antistatic layer, and adhesive layer were measured in accordance with ISO 4591:1992 (JIS K7130:1999) B1 method (a method for measuring thickness by the mass method of a sample taken from a plastic film or sheet).

[0137] (Base layer elongation rate) The test was carried out according to the following steps 1 to 4. 1. The coating liquid for the primer layer before curing was applied to a silicone-coated PET film (NS Separator A (product name), manufactured by Nakamoto Pax Co., Ltd.) so that the thickness after curing would be 100 μm, and then dried to produce a PET film with a primer layer. 2. The obtained PET with the underlayer was cut into strips of 20 mm width, and the PET was peeled off to obtain a molded product with only the underlayer. 3. The molded product with only the base layer was rolled up from the edge to form a cylindrical shape. 4. The cylindrical molded product was stretched using a tensile tester (Orientec RTC-131-A) with a clamping distance of 10 mm before tensioning at a rate of 100 mm / min, and the elongation (mm) until breakage (hereinafter also referred to as "elongation at break") was measured. The measurement was carried out at 25°C. Elongation (%) = Elongation at break (mm) / Distance between grips before tension (10 mm) × 100

[0138] (surface resistance value) The surface resistance (Ω / □) of the film was measured in accordance with IEC 60093:1980: double ring electrode method using an ultra-high resistance meter R8340 (Advantec) at an applied voltage of 500 V for 1 minute.

[0139] (Adhesive layer peeling degree) The films prepared in each example were cut into strips (50 mm wide, 100 mm long). The films were clamped and set between the grips of a tensile tester (Orientec RTC-131-A). The films were stretched to an elongation of 200% at a grip distance of 25 mm and a speed of 100 mm / min before stretching. A cross-cut was made in the center of the film according to the cross-cut adhesion test method specified in JIS-K5600-5-6:1999. Then, Cellotape (CT-18, manufactured by Nichiban Co., Ltd.) was applied. The Cellotape was pressed by rolling a roller back and forth 20 times over the Cellotape, and then peeled off by hand. Test results corresponding to "Test result classification 0: The edges of the cut are completely smooth and no peeling occurs at any of the grid squares" as specified in JIS-K5600-5-6:1999 were evaluated as "good" (A), and those not corresponding to this were evaluated as "bad" (B).

[0140] (Mold releasability) A 100 μm thick, 15 cm x 15 cm square aluminum foil was placed on a 3 mm thick, 15 cm x 15 cm square first metal plate (SUS304). A 100 mm thick, 15 cm x 15 cm square spacer with a 10 cm x 8 cm rectangular hole in the center was placed on the aluminum foil, and 2 g of the following epoxy resin composition was placed near the center of the hole. A 15 cm x 15 cm square film was then placed on top of the aluminum foil, with the adhesive layer facing the spacer. A 3 mm thick, 15 cm x 15 cm square second metal plate (SUS304) was placed on top of the film to prepare a laminate sample. The laminate sample was pressed at 180°C and 10 MPa for 5 minutes to cure the epoxy resin composition. The laminate of the film, the cured epoxy resin composition layer, and the aluminum plate was cut into 25 mm wide pieces to prepare five test pieces. The 180° peel strength of each test piece at 180°C was measured at a rate of 100 mm / min using a tensile tester (Orientec RTC-131-A). The average peel strength (unit: N / cm) was calculated from the force (N) vs. grip movement distance curve over a grip movement distance of 25 mm to 125 mm. The arithmetic mean of the average peel strengths of the five test pieces was calculated, and this value was used as the peel strength of the film to the epoxy resin at 180°C. A value of 0.5 N / cm or less was rated as good (A), and a value of 0.5 N / cm or more was rated as poor (B).

[0141] The epoxy resin composition was prepared by grinding and mixing the following components in a supermixer for 5 minutes. The cured product of this epoxy resin composition had a glass transition temperature of 135°C, a storage modulus of 6 GPa at 130°C, and a storage modulus of 1 GPa at 180°C. 8 parts by mass of phenylene skeleton-containing phenol aralkyl epoxy resin (softening point 58°C, epoxy equivalent 277g / eq) Bisphenol A epoxy resin (melting point 45°C, epoxy equivalent 172g / eq) 2 parts by mass 2 parts by mass of phenylene skeleton-containing phenol aralkyl resin (softening point 65°C, hydroxyl group equivalent 165g / eq) 2 parts by mass of phenol novolac resin (softening point 80°C, hydroxyl group equivalent 105g / eq), Curing accelerator (triphenylphosphine) 0.2 parts by mass Inorganic filler (fused spherical silica with a median diameter of 16 μm) 84 parts by mass Carnauba wax 0.1 parts by weight Carbon black 0.3 parts by mass Coupling agent (3-glycidoxypropyltrimethoxysilane) 0.2 parts by mass

[0142] (Mold test) The sealing test was carried out using a transfer molding machine (G-LINE Manual System, Apic Yamada Co., Ltd.). A semiconductor element was fixed to a copper lead frame measuring 70 mm x 230 mm. The same epoxy resin composition as that used in the mold releasability evaluation was used as the sealing resin. Five 5mm x 5mm projections were provided at equal intervals on the upper mold. A 190mm wide roll of film was set in the upper mold using a roll-to-roll method. After placing the lead frame with the semiconductor element secured to it in the lower mold, the film was vacuum-sucked onto the upper mold, and the mold was then closed. The curable resin was poured into the upper mold. To expose the semiconductor element from the resin, the adhesive surface of the film on the five projections on the upper mold was brought into direct contact with the semiconductor element secured to the lower mold, and the encapsulation resin was filled around this area. After applying pressure for five minutes, the mold was opened and the encapsulated body was removed. The peeling state between the film and resin encapsulation area and the appearance of the exposed area of ​​the encapsulated body were visually inspected and evaluated according to the following criteria.

[0143] - Peeling state between film and resin sealing part - Good (A): Peeled off normally. Bad (B): The lead frame did not peel properly and came off the lower mold.

[0144] -Appearance of exposed part of semiconductor element- Good (A): Less than two adhesive layers transferred from the film to the semiconductor element Bad (B): Two or more adhesive layers have been transferred from the film to the semiconductor element.

[0145] The sealing conditions are as follows: Mold clamping pressure: 0.5 MPa per semiconductor element Transfer pressure: 5MPa Mold temperature (sealing temperature): 180℃

[0146] The evaluation results are shown in Tables 1 and 2. In Tables 1 and 2, "-" indicates not applicable.

[0147] [Table 1]

[0148] [Table 2]

[0149] In Tables 1 and 2, it was confirmed that Examples 1 to 9 and 13 to 17 had the undercoat layer of the present disclosure, and therefore the components of the adhesive layer were prevented from migrating to the encapsulant even when stretched. [Industrial Applicability]

[0150] The film of the present disclosure has excellent releasability when encapsulating a semiconductor element with a curable resin, and can reduce the occurrence of defects in the appearance of the encapsulated body due to the release film.The film of the present disclosure can be used as a release film to produce a semiconductor package such as an integrated circuit that integrates semiconductor elements such as transistors and diodes, source electrodes, sealing glass, and other electronic components.

[0151] The disclosure of Japanese Patent Application No. 2021-005780 is incorporated herein by reference in its entirety. All publications, patent applications, and technical standards mentioned in this specification are incorporated by reference into this specification to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0152] 1 film 2 Base material 3 Base layer 4 Adhesive layer

Claims

1. A release film comprising a substrate, a foundation layer, and an adhesive layer in this order, the substrate is at least one selected from fluororesin, polymethylpentene, syndiotactic polystyrene, polycycloolefin, silicone rubber, polyester elastomer, polybutylene terephthalate, and unstretched nylon; the underlayer contains a reaction cured product of a (meth)acrylic polymer and a curing agent, the underlayer has an acid value of 1 to 80 mgKOH / g and a thickness of 0.1 to 3.0 μm, the curing agent is at least one selected from a metal chelate and an epoxy compound, the adhesive layer contains a reaction-cured product of a hydroxy group-containing (meth)acrylic polymer and a polyfunctional isocyanate compound, A release film characterized in that, when a base layer has a thickness of 100 μm and a width of 20 mm, the distance between grippers before pulling is 10 mm in width, the temperature is 25°C, and the speed is 100 mm / min, the elongation of the base layer calculated by the following formula is 90% or more. Elongation (%) = (elongation at break (mm)) × 100 / (distance between grippers before tension (mm))

2. A release film comprising a substrate, a foundation layer, and an adhesive layer in this order, the substrate is at least one selected from fluororesin, polymethylpentene, syndiotactic polystyrene, polycycloolefin, silicone rubber, polyester elastomer, polybutylene terephthalate, and unstretched nylon; the underlayer comprises a reaction-cured product of a (meth)acrylic polymer and a curing agent which is at least one selected from the group consisting of a metal chelate and an epoxy compound, the underlayer having an acid value of 1 to 80 mgKOH / g and a thickness of 0.1 to 3.0 μm, the (meth)acrylic polymer includes a carboxy group-containing (meth)acrylic polymer, A release film, wherein the adhesive layer contains a reaction-cured product of a hydroxy group-containing (meth)acrylic polymer and a polyfunctional isocyanate compound.

3. 3. The release film according to claim 2, wherein the elongation of the base layer is 90% or more when measured in a tensile test with a thickness of 100 μm and a width of 20 mm, a gripping distance of 10 mm before tension, at 25° C., and at a speed of 100 mm / min, and calculated by the following formula: Elongation (%) = (elongation at break (mm)) × 100 / (distance between grippers before tension (mm))

4. The release film according to any one of claims 1 to 3, wherein the curing agent contains a metal chelate, and the amount of the metal chelate per 100 parts by mass of the (meth)acrylic polymer is 0.1 to 10 parts by mass.

5. The release film according to any one of claims 1 to 4, wherein the curing agent comprises an epoxy compound, and the amount of the epoxy compound per 100 parts by mass of the (meth)acrylic polymer is 0.1 to 10 parts by mass.

6. The release film according to any one of claims 1 to 5, wherein the substrate comprises a fluororesin.

7. 7. The release film according to claim 6, wherein the fluororesin comprises at least one selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, and a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.

8. The release film according to any one of claims 1 to 7, wherein the substrate is corona-treated or plasma-treated.

9. The release film according to any one of claims 1 to 8, further comprising an antistatic layer between the underlayer and the adhesive layer.

10. The release film according to any one of claims 1 to 9, which is a release film used in a step of encapsulating a semiconductor element with a curable resin.

11. Placing the release film according to any one of claims 1 to 10 on an inner surface of a mold; placing a substrate having a semiconductor element fixed thereto in the mold on which the release film is disposed; encapsulating the semiconductor element in the mold with a curable resin to produce an encapsulated body; Releasing the encapsulated body from the mold; A method for manufacturing a semiconductor package, comprising:

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