Release film

Abstract

The present invention provides a release film that offers excellent conformability and yields molded products with a good appearance. [Solution] The release film 11 of the present invention satisfies the following (a): (a) In thermomechanical analysis (TMA) measurement, under the conditions of a heating rate of 2°C / min and a load of 500mN, the TMA curve obtained from the relationship between the temperature measured by tensile measurement of the release film and the dimensional change in the length of the release film is such that the dimensional change at 140°C is X1 (%), the dimensional change at 160°C is X2 (%), and (X2-X1) / (160-140) is α1, and α1 is between 0.1 and 1.0.

Description

Technical Field

[0001] The present invention relates to a release film.

Background Art

[0002] Release films are used, for example, when producing molded articles or when producing laminates obtained by bonding different materials together. For example, when producing a flexible printed circuit board (hereinafter also referred to as "FPC") in which a coverlay film (hereinafter also referred to as "CL film") is bonded via an adhesive to a flexible film with exposed circuits (hereinafter also referred to as "circuit-exposed film") by hot pressing, a release film is disposed between the coverlay film and a hot plate, and is hot pressed together with the hot plate (for example, Patent Document 1). Further, for example, in a semiconductor device manufacturing process, it is known that a release film is disposed between a mold and a molding target, and the molding target on which electronic members such as semiconductor elements are mounted is resin-sealed by a molding method such as a transfer molding method or a compression molding method to manufacture a semiconductor device (for example, Patent Documents 2 to 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of Invention

Problems to be Solved by the Invention

[0004] In recent years, with the miniaturization and increased functionality of electronic devices, flexible printed circuit boards (FPCs) have become increasingly miniaturized, and special bump technologies are being developed to achieve the mounting capabilities required by this miniaturization. Therefore, release films require high conformability to follow the fine structure. In addition, wrinkles and distortions that occur in the release film may be transferred to the surface of molded products obtained using the release film, so it is necessary to obtain molded products with a good appearance. However, conventional release films, such as those described in Patent Documents 1 to 4, had room for improvement in terms of achieving both high conformability and a good appearance. [Means for solving the problem]

[0005] The inventors of this invention conducted diligent research to obtain high conformability and a good appearance, and found that it is effective to devise an index related to the amount of dimensional change of the release film in response to heat as an indicator for controlling the properties of the release film, and to control this index, thus completing the present invention.

[0006] According to the present invention, the following release films and related technologies are provided.

[0007] [1] A release film that meets the following requirement (a): (a) In thermomechanical analysis (TMA) measurements, under conditions of a heating rate of 2°C / min and a load of 500mN, the TMA curve obtained from the relationship between the temperature measured by tensile testing of the release film and the dimensional change in the length of the release film is such that the dimensional change at 140°C is X1 (%), the dimensional change at 160°C is X2 (%), and (X2-X1) / (160-140) is α1, where α1 is between 0.1 and 1.0. [2] The release film described in [1], further satisfying requirement (b) below. (b) Thermomechanical analysis (TMA) shows that when the temperature is increased from 30°C to 150°C at a rate of 2°C / min under a tensile load of 500mN, the dimensional change (Y1) of the release film is between 4% and 80%. [3] The release film described in [1] or [2], which further satisfies requirement (c) below. (c) When dynamic viscoelasticity (DMA) measurements were taken under the conditions of a heating rate of 5°C / min and a frequency of 1 Hz, the storage modulus at 150°C was 10 MPa to 500 MPa. [4] A release film according to any one of [1] to [3], which further satisfies requirement (d) below. (d) The release film has a 5% tensile strength (5% modulus) of 0.9 MPa to 3.0 MPa at 150°C. [5] A release film according to any one of [1] to [4], which further satisfies requirement (e) below. (e) Let S1 (MPa) be the breaking strength at 25°C and S2 (MPa) be the breaking strength at 150°C, and let β1 be (1 - (S1 - S2) / S1), then β1 is between 0.2 and 0.9. [6] A release film according to any one of [1] to [5], comprising a multilayer structure including a release layer which forms at least one surface of the release film and a base layer made of a material different from the release layer. [7] The release film according to [6], wherein the base layer comprises an elastomer. [8] A release film according to any one of [1] to [7], used in a encapsulation process with a thermosetting resin. [Effects of the Invention]

[0008] According to the present invention, a release film is provided that yields molded articles with excellent conformability and a good appearance. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the cross-section of the release film of this embodiment. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to those of actual items.

[0011] In the present specification, the notation "a to b" in the description of numerical ranges means a or more and b or less, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% or more and 5 mass% or less".

[0012] <Release Film> The release film of the present embodiment may have a single-layer structure, or may have a multilayer structure including at least one surface of the release film, that is, a release layer serving as a release surface, and a base material layer made of a material different from that of the release layer. Hereinafter, details will be described by taking the case where the release film has a multilayer structure as an example.

[0013] Figure 1 is a cross-sectional view schematically showing a cross section of the release film of the present embodiment. As shown in Figure 1, the release film 11 of the present embodiment includes a base material layer 2 and a release layer 1 laminated on the base material layer 2.

[0014] [Requirement (a)] The release film 11 of the present embodiment satisfies the following requirement (a). (a) In a thermomechanical analysis (TMA) measurement, in a TMA curve obtained from the relationship between the temperature at which the release film is subjected to tensile measurement under the conditions of a temperature rise rate of 2°C / min and a load of 500 mN, and the dimensional change amount of the length of the release film, when the dimensional change amount at 140°C is defined as X1 (%), the dimensional change amount at 160°C is defined as X2 (%), and (X2-X1) / (160-140) is defined as α1, α1 is 0.1 to 1.0.

[0015] Thereby, the followability of the release film 11 is excellent, and a molded article with good appearance can be obtained by using the release film 11. Although the details of such a reason are not clear, the dimensional change amount at 140°C and the dimensional change amount at 160°C intend the dimensional change of the release film during heating in a mold when the release film is used. Therefore, by setting the change amount at 140°C and 160°C to be equal to or more than the lower limit value, appropriate deformation is achieved to obtain good followability, while by setting the change amount to be equal to or less than the upper limit value, shape recovery is performed to suppress the occurrence of wrinkles and distortion, which is considered to improve the appearance of the obtained molded article.

[0016] In (a) above, α1 is 0.1 to 1.0, preferably 0.1 to 0.9, and more preferably 0.1 to 0.7.

[0017] Furthermore, the dimensional change (X1) at 140°C is preferably 8-60%, more preferably 10-55%.

[0018] The dimensional change (X2) at 160°C is preferably 15-65%, more preferably 23-58%.

[0019] [Requirements (a1)] The release film 11 of this embodiment is preferably further satisfied with the following requirement (a1). (a1) In thermomechanical analysis (TMA) measurements, under the conditions of a heating rate of 2°C / min and a load of 500mN, the TMA curve obtained from the relationship between the temperature measured by tensile testing of the release film and the dimensional change in the length of the release film is such that the dimensional change at 25°C is X3 (%), the dimensional change at 100°C is X4 (%), and (X4-X3) / (100-25) is α2. In this case, α1 / α2 is preferably 0.1 to 20, more preferably 0.2 to 18.

[0020] This improves the conformability of the release film 11 to the mold when it is placed on the mold. It also suppresses wrinkles and distortions in the release film 11, and prevents these wrinkles and distortions from being transferred to the molded product.

[0021] [Requirement (b)] The release film 11 of this embodiment is preferably further satisfied with the following requirement (b). (b) Thermomechanical analysis (TMA) shows that when the temperature is increased from 30°C to 150°C at a rate of 2°C / min with a tensile load of 500mN, the dimensional change (Y1) of the release film is between 4% and 80%.

[0022] This improves the conformability of the release film 11 to the mold when it is placed on the mold. It also suppresses wrinkles and distortions in the release film 11, and prevents these wrinkles and distortions from being transferred to the molded product.

[0023] Furthermore, the dimensional change (Y1) (%) is 4% to 80%, preferably 10% to 70%, and more preferably 17% to 60%.

[0024] [Requirement (c)] The release film 11 of this embodiment is preferably further satisfied with the following requirement (c). (c) When dynamic viscoelasticity (DMA) measurements were taken under the conditions of a heating rate of 5°C / min and a frequency of 1 Hz, the storage modulus at 150°C was 10 MPa to 500 MPa.

[0025] The storage modulus of the release film 11 at 150°C is intended to be the storage modulus when the release film 11 is placed in the mold and heated and compressed. By setting the storage modulus of the release film 11 at 150°C within the above numerical range, it becomes easier to suppress the occurrence of wrinkles and distortions while improving mold conformability during vacuum adhesion.

[0026] The storage modulus at 150°C is 10 to 500 MPa, preferably 12 to 200 MPa, and more preferably 15 to 100 MPa.

[0027] [Requirement (d)] The release film 11 of this embodiment is preferably further satisfied with the following requirement (d). (d) The release film has a 5% tensile strength (5% modulus) of 0.9 MPa to 3.0 MPa at 150°C.

[0028] This allows for effective control of the release film 11's ability to return to its original shape in response to stretching. As a result, effective recovery from stretching is achieved, making it easier to suppress wrinkles and distortions that may occur when using the release film.

[0029] At 150°C, the 5% tensile strength (5% modulus) is 0.9 MPa to 3.0 MPa, preferably 1.0 MPa to 2.5 MPa, and more preferably 1.0 MPa to 2.0 MPa.

[0030] Claim 5 [Requirement (e)] The release film 11 of this embodiment is preferably further satisfied with the following requirement (e). (e) Let S1 (MPa) be the breaking strength at 25°C and S2 (MPa) be the breaking strength at 150°C, and let β1 be (1 - (S1 - S2) / S1), then β1 is between 0.2 and 0.9.

[0031] This allows for a moderate degree of flexibility during heating while maintaining strength against deformation. As a result, good conformability is achieved while further reducing the occurrence of wrinkles and distortions in the release film 11.

[0032] β1 is 0.2 to 0.9, preferably 0.3 to 0.8, and more preferably 0.4 to 0.8.

[0033] The indicators (a) to (e) above can be achieved by appropriately selecting and combining known methods, such as the selection of raw materials for the base layer 2, the type and amount of raw materials for the release layer 1, the method of preparing the raw materials, and the method of manufacturing the release film 11, and by using methods different from conventional methods. Specifically, for example, selecting elastomer components as raw materials for the base layer 2, appropriately controlling the crosslinking density and crosslinking structure of the resin, improving the blending ratio and dispersibility of the inorganic filler, and aging the release film 11 during its manufacturing process are all factors that can bring the above indicators within the desired numerical range.

[0034] [Overall thickness] The thickness of the release film 11 is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 120 μm or less, and even more preferably 30 μm or more and 90 μm or less.

[0035] The following describes each layer of the release film 11 of this embodiment.

[0036] [Release layer] The release layer 1 forms one side of the release film 11 and has a release surface 3.

[0037] The thickness of the release layer 1 is preferably 0.1 μm or more and 150 μm or less, more preferably 0.5 μm or more and 100 μm or less, and even more preferably 1 μm or more and 5 μm or less. By setting the thickness of the release layer 1 to be greater than or equal to the lower limit, the rigidity of the release film 11 is increased, making it easier to suppress excessive deformation and wrinkle formation. As a result, mold conformability and dimensional stability can be obtained. On the other hand, by setting the thickness of the release layer 1 to be less than or equal to the upper limit, the rigidity of the release film 11 can be controlled, and a good balance between mold conformability and release properties can be achieved.

[0038] (First resin composition) The release layer 1 is composed of a first resin composition containing resin. The first resin composition preferably contains one or more resins selected from, for example, silicone resins, fluororesins, polyolefin resins, polyester resins, epoxy resins, polyamide resins, acrylic resins, and melamine resins. In particular, from the viewpoint of obtaining a release surface 3 with good release properties, it is more preferable to include one or more selected from silicone resin, fluororesin, melamine resin, epoxy resin, acrylic resin, and polyolefin resin, and even more preferable to include melamine resin and acrylic resin.

[0039] (Silicone resin) The silicone resin is not particularly limited. For example, various known or commercially available siloxane polymers and other compounds containing two or more siloxane bonds (-Si-O-) can be used.

[0040] Preferably, the silicone resin contains one or two selected from, for example, vinyl group-containing organopolysiloxanes and organohydrogenpolysiloxanes. This provides rubber-like properties such as elasticity and compressibility of the silicone, making it easier to obtain sufficient elongation and shape recovery properties for the release film.

[0041] (Fluororesin) Examples of the fluororesins mentioned above include polymers of monomers such as tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, and perfluoroalkyl vinyl ether, or copolymers of two or more monomers. These may be used individually or in combination of two or more.

[0042] (Polyolefin resin) The polyolefin resins mentioned above are resins having structural units derived from α-olefins such as ethylene, propylene, and butene, and known resins can be used. Specifically, examples of polyolefin resins include polyethylene (PE), such as low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (mLLPE); polypropylene (PP); polyvinyl alcohol (PVA); ethylene-vinyl acetate copolymer (EVA); ethylene-methyl acrylate copolymer (EMA); ethylene-acrylic acid copolymer (EAA); ethylene-methyl methacrylate copolymer (EMMA); ethylene-ethyl acrylate copolymer (EEA); ethylene-methacrylic acid copolymer (EMAA); ionomer resins; ethylene-vinyl alcohol copolymer (EVOH); and cyclic olefin resins (COP). These may be used individually or in combination of two or more types.

[0043] (Polyester resin) Examples of the polyester resins mentioned above include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), polyhexamethylene terephthalate resin (PHT), and polyethylene naphthalate resin (PEN). These may be used individually or in combination of two or more types.

[0044] (Epoxy resin) The epoxy resins mentioned above can be any monomer, oligomer, or polymer that has two or more epoxy groups in one molecule, regardless of its molecular weight or molecular structure. Specific examples of such epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol M type epoxy resin (4,4'-(1,3-phenylenediisopridiene)bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4'-(1,4-phenylenediisopridiene)bisphenol type epoxy resin), bisphenol Z type epoxy resin (4,4'-cyclohexydiene bisphenol type epoxy resin), and other bisphenol type epoxy resins; novolac type epoxy resins such as phenol novolac type epoxy resin, brominated phenol novolac type epoxy resin, cresol novolac type epoxy resin, tetraphenol group ethane type novolac type epoxy resin, and novolac type epoxy resin having a condensed ring aromatic hydrocarbon structure; biphenyl type epoxy resin; xyl Aalkyl epoxy resins such as elenium-type epoxy resins and biphenylaralkyl-type epoxy resins; epoxy resins having a naphthalene skeleton such as naphthylene ether-type epoxy resins, naphthol-type epoxy resins, naphthalene-type epoxy resins, naphthalenediol-type epoxy resins, bifunctional or tetrafunctional epoxy-type naphthalene resins, binaphthyl-type epoxy resins, and naphthalene aralkyl-type epoxy resins; anthracene-type epoxy resins; phenoxy-type epoxy resins; dicyclopentadiene-type epoxy resins; norbornene-type epoxy resins; adamantane-type epoxy resins; fluorene-type epoxy resins, phosphorus-containing epoxy resins, alicyclic epoxy resins, aliphatic chain epoxy resins, bisphenol A novolac-type epoxy resins, bixylenol-type epoxy resins, triphenolmethane-type epoxy resins, trihydroxyphenylmethane-type epoxy resins, tetraphenyloleethane-type epoxy resins, and heterocyclic epoxy resins such as triglycidyl isocyanurate;It may contain one or more selected from glycidylamines such as N,N,N',N'-tetraglycidylmetoxylendiamine, N,N,N',N'-tetraglycidylbisaminomethylcyclohexane, and N,N-diglycidylaniline; copolymers of glycidyl (meth)acrylate and compounds having an ethylenically unsaturated double bond; epoxy resins having a butadiene structure; diglycidyl ethers of bisphenols; diglycidyl ethers of naphthalenediols; and glycidyl ethers of phenols.

[0045] (Polyamide resin) Examples of the polyamide resins mentioned above include aliphatic polyamides and aromatic polyamides. Specific examples of aliphatic polyamides include polyamide 6, polyamide 6,6, polyamide 6-6,6 copolymer, polyamide 11, and polyamide 12. Specific examples of aromatic polyamides include polyamide 61, polyamide 66 / 6T, polyamide 6T / 6, and polyamide 12 / 6T.

[0046] (Melamine resin) The melamine resins described above can be obtained, for example, by polycondensation of a melamine compound and formaldehyde under neutral or weakly alkaline conditions. Specifically, examples include methylated melamine resins, alkylated melamine resins such as butylated melamine resins, methylolated melamine resins, alkyl etherated melamines, and the like.

[0047] (Acrylic resin) Specific examples of acrylic resins include acrylic acid esters such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; and resins composed of monomers such as acrylonitrile, methacrylonitrile, and acrylamide. The constituent monomers of the acrylic resin include one or more monomers from these examples. Furthermore, the constituent monomers of the acrylic resin may also include monomers other than those listed above. Derivatives of these monomers may also be included.

[0048] [others] In addition to the resin described above, the first resin composition may contain other components as long as they do not impair the properties of the release film 11. These other components are not limited to, but may include solvents, inorganic fillers, coupling agents, antistatic agents, leveling agents, dispersants, pigments, dyes, antioxidants, flame retardants, thermal conductivity enhancers, etc., as appropriate. Representative components are described below.

[0049] (solvent) The first resin composition may contain, for example, a solvent, depending on the method for manufacturing the release layer 1. If a solvent is included, the release layer 1 can be produced by dissolving the first resin composition in the solvent and applying it. The solvent is not limited, but specifically, examples include aliphatic hydrocarbons such as water, pentane, hexane, cyclohexane, heptane, methylcyclohexane, ethylcyclohexane, octane, decane, dodecane, and tetradecane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, trifluoromethylbenzene, and benzotrifluoride; ethers such as diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, cyclopentyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, 1,4-dioxane, 1,3-dioxane, and tetrahydrofuran; haloalkanes such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, and 1,1,2-trichloroethane; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide. These can be used individually or in combination of two or more types.

[0050] (Inorganic filler) In this embodiment, the first resin composition may also contain an inorganic filler. This allows for the formation of fine irregularities on the surface of the release layer 1, thereby improving release properties. The inorganic filler is not particularly limited, but examples include particles made from one or more materials obtained from the group consisting of diatomaceous earth, iron oxide, titanium oxide, barium oxide, magnesium oxide, cerium oxide, magnesium carbonate, zinc carbonate, glass wool, mica, calcium carbonate, zinc oxide, alumina, crystalline silica, amorphous silica, fused silica, and zeolite. Among these, one or more materials obtained from the group consisting of calcium carbonate, zinc oxide, alumina, crystalline silica, amorphous silica, fused silica, and zeolite are preferred. Furthermore, depending on the method of silica synthesis, fumed silica (flame-processed silica), calcined silica, precipitated silica, etc., may be used. These inorganic fillers may be used individually or in combination of two or more types.

[0051] Inorganic fillers, for example, have a specific surface area of ​​50-400 m² as determined by the BET method. 2 It is preferable that the amount be / g, and 100-400m 2 It is more preferable that it be / g. Furthermore, the average primary particle size of the inorganic filler is preferably, for example, 1 to 100 nm, and more preferably about 5 to 20 nm.

[0052] By using an inorganic filler that falls within the specified range of specific surface area and average particle size, the hardness and mechanical strength of the formed release layer 1 can be improved, making it easier to improve the balance between release properties, mold conformability, and dimensional stability.

[0053] (Silane coupling agent) Silane coupling agents can have hydrolyzable groups. These hydrolyzable groups are hydrolyzed by water to form hydroxyl groups, and these hydroxyl groups undergo a dehydration condensation reaction with hydroxyl groups on the surface of the inorganic filler, thereby modifying the surface of the inorganic filler.

[0054] Furthermore, the silane coupling agent may include a silane coupling agent having hydrophobic groups. As a result, these hydrophobic groups are imparted to the surface of the inorganic filler, which reduces the cohesive force of the inorganic filler in the first resin composition and consequently in the release layer 1 (in the case of silica particles, aggregation due to hydrogen bonding by silanol groups is reduced), and as a result, the dispersibility of the inorganic filler in the release layer 1 is presumed to improve. This increases the interface between the inorganic filler and the rubber matrix, and enhances the reinforcing effect of the inorganic filler. Furthermore, it is presumed that the slipperiness of the inorganic filler within the matrix is ​​improved during deformation of the rubber matrix. And, due to the improved dispersibility and slipperiness of the inorganic filler, the mechanical strength of the release layer 1 due to the inorganic filler (e.g., mold conformability, dimensional stability, etc.) is improved.

[0055] Furthermore, the silane coupling agent may include a silane coupling agent having vinyl groups. This introduces vinyl groups to the surface of the inorganic filler. Therefore, when the release layer 1 hardens, that is, when the vinyl groups of the vinyl group-containing organopolysiloxane (A) and the hydride groups of the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction to form a network (crosslinked structure), the vinyl groups of the inorganic filler (in the case of silica particles) also participate in the hydrosilylation reaction with the hydride groups of the organohydrogenpolysiloxane (B), thus incorporating the inorganic filler into the network. This makes it possible to achieve lower hardness and higher modulus in the formed release layer 1.

[0056] As a silane coupling agent, a silane coupling agent having a hydrophobic group and a silane coupling agent having a vinyl group can be used in combination.

[0057] Examples of silane coupling agents include those represented by the following formula (a).

[0058] Y n -Si-(X) 4-n (a) In formula (a) above, n represents an integer from 1 to 3. Y represents a functional group having a hydrophobic group, a hydrophilic group, or a vinyl group, where n is a hydrophobic group when n is 1, and at least one of them is a hydrophobic group when n is 2 or 3. X represents a hydrolyzable group.

[0059] Hydrophobic groups are alkyl groups, aryl groups, or hydrocarbon groups having 1 to 6 carbon atoms, such as methyl groups, ethyl groups, propyl groups, and phenyl groups, with methyl groups being preferred.

[0060] Furthermore, hydrophilic groups include, for example, hydroxyl groups, sulfonic acid groups, carboxyl groups, or carbonyl groups, with hydroxyl groups being preferred among them. While hydrophilic groups may be included as functional groups, it is preferable that they are not included from the viewpoint of imparting hydrophobicity to the silane coupling agent.

[0061] Furthermore, hydrolyzable groups include alkoxy groups such as methoxy groups and ethoxy groups, chloro groups, or silazane groups, and among these, silazane groups are preferred due to their high reactivity with inorganic fillers (in the case of silica particles). Note that those having a silazane group as a hydrolyzable group are, due to their structural characteristics, (Y in formula (a) above n It will have two -Si-) structures.

[0062] Specific examples of silane coupling agents represented by the above formula (a) include, for example, alkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, and decyltrimethoxysilane, which have a hydrophobic functional group; chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and phenyltrichlorosilane; and hexamethyldisilazane, which have a hydrophobic functional group. Examples of materials having a vinyl group include alkoxysilanes such as methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane. Among these, considering the above, hexamethyldisilazane is particularly preferred as the material having a hydrophobic group, and divinyltetramethyldisilazane is preferred as the material having a vinyl group.

[0063] (catalyst) The first resin composition may contain a catalyst when forming the release layer 1 by a curing reaction. Examples of catalysts include platinum or platinum compounds. Known platinum or platinum compounds can be used, such as platinum black, platinum supported on silica or carbon black, chloroplatinic acid or an alcoholic solution of chloroplatinic acid, a complex salt of chloroplatinic acid and an olefin, or a complex salt of chloroplatinic acid and a vinylsiloxane. Platinum or platinum compounds may be used individually or in combination of two or more.

[0064] In this embodiment, the content ratio of each component of the first resin composition is not particularly limited, but for example, it can be set as follows.

[0065] In this embodiment, the upper limit of the inorganic filler content may be, for example, 60 parts by weight or less, preferably 50 parts by weight or less, and more preferably 40 parts by weight or less, based on 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A). This improves the mechanical strength of the release film 11, such as hardness and tear strength, and improves the balance of release properties, mold conformability, and dimensional stability. The lower limit of the inorganic filler content is not particularly limited, but may be, for example, 10 parts by weight or more, based on 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A).

[0066] The silane coupling agent is preferably contained in a ratio of 5 to 100 parts by weight, and more preferably 5 to 40 parts by weight, per 100 parts by weight of vinyl group-containing organopolysiloxane (A). This ensures that the dispersibility of the inorganic filler in the release layer 1 is reliably improved.

[0067] The content of organohydrogenpolysiloxane (B) is preferably, for example, 0.5 parts by weight to 20 parts by weight, and more preferably 0.8 parts by weight to 15 parts by weight, based on 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A), inorganic filler, and silane coupling agent. A content of (B) within the above range may enable a more effective curing reaction.

[0068] [Method for manufacturing release layer] Next, the manufacturing method for the release layer 1 of this embodiment will be described. In this embodiment, the release layer 1 can be manufactured by preparing the first resin composition described above, forming the first resin composition into a film, and curing it.

[0069] The first resin composition may be dissolved in a solvent to form a paste or a varnish. The first resin composition is processed into a film and cured to form the release layer 1. Specifically, the first resin composition is formed into a film by extrusion molding, calendering, press molding, coating, etc. The surface shape of a roll or the like may be transferred or embossed during film formation.

[0070] By going through the above steps, a release layer 1 using the first resin composition of this embodiment can be obtained.

[0071] [Base material layer 2] In the release film 11 of this embodiment, the base material layer 2 is used to provide appropriate rigidity in order to exhibit the shape stability, manufacturing stability, and release function of the release layer of the release film 11.

[0072] The thickness of the base layer 2 is preferably 5 μm or more and 130 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 20 μm or more and 80 μm or less. By setting the thickness of the base material layer 2 to be greater than or equal to the lower limit mentioned above, the rigidity of the release film 11 is increased, making it easier to suppress excessive deformation and wrinkle formation. As a result, mold conformability and dimensional stability can be obtained. On the other hand, by setting the thickness of the base material layer 2 to be less than or equal to the upper limit mentioned above, the rigidity of the release film 11 can be controlled, and a good balance between mold conformability and release properties can be achieved.

[0073] The base layer 2 is composed of a second resin composition containing resin.

[0074] Examples of resins included in the second resin composition include one or more selected from polyester resins, polyamide resins, and polyolefin resins, as well as elastomers thereof. Examples of the polyester resin, polyamide resin, and polyolefin resin mentioned above are those similar to those described in the release layer 1 above.

[0075] Elastomers are block copolymers in which hard segments and soft segments are chemically bonded to the molecular structure, thereby possessing both hardness and flexibility. In this embodiment, the elastomer is preferably a thermoplastic elastomer (TPE). Specifically, examples of elastomers include polyester elastomers, polyamide elastomers, and polyolefin elastomers. The above-mentioned polyester elastomer is not limited to any particular type, and can include an elastomer containing polyester as the hard segment and polyether or polyester as the soft segment. Specifically, examples of polyester elastomers include polyester-polyether elastomers and polyester-polyester elastomers. Examples of polyester-polyether elastomers include those using polybutylene terephthalate (PBT) as the hard segment and polyether as the soft segment. This improves heat resistance while providing good flexibility at low temperatures and excellent mechanical strength.

[0076] The Shore D hardness of the elastomer component is preferably D20 to D100, more preferably D30 to D90, and even more preferably D40 to D80. This improves heat resistance, provides good flexibility at low temperatures, and also allows for excellent mechanical strength.

[0077] Furthermore, a stretched film may be used as the base layer 2, and the stretching can be carried out using known methods such as sequential biaxial stretching, simultaneous biaxial stretching, and tubular stretching.

[0078] [Method for manufacturing release film] The release film 11 can be manufactured using known methods such as co-extrusion, extrusion lamination, dry lamination, or inflation. The release layer 1 may also be formed on the base layer 2 by coating the surface of the base layer 2 with a first resin composition prepared in paste form. In the release film 11, for example, the release layer 1 and the base layer 2 may be manufactured separately and then joined together using a laminator or the like. Alternatively, the release layer 1 and the base layer 2 may be joined directly, or they may be joined via an adhesive layer. The method for manufacturing the base layer 2 is not limited to this method, and specific examples include inflation extrusion and T-die extrusion.

[0079] [Uses and methods of using release film] The release film 11 of this embodiment is used in a encapsulation process using a thermosetting resin. In particular, it is used in the resin encapsulation process of semiconductor devices, where it is placed between the mold to which the encapsulation resin is supplied and the semiconductor device to be resin-encapsulated. That is, it may be a so-called mold release film, or it may be used for other purposes. Other uses include, for example, when manufacturing a flexible printed circuit board (hereinafter also called "FPC") by bonding a coverlay film (hereinafter also called "CL film") to a flexible film with exposed circuits (hereinafter also called "circuit exposed film") via an adhesive using a heat press, where the release film is placed between the cover film and the mold. It can also be used as, for example, a release film when curing a prepreg of a thermosetting resin such as CFRP, a release film for molding thermosetting resins, or a decorative transfer release film for printing on products with three-dimensional shapes.

[0080] The following describes an example of a method for manufacturing a resin-encapsulated semiconductor device using a release film 11.

[0081] The method for manufacturing a resin-encapsulated semiconductor device includes the following steps. (Process 1) Semiconductor device preparation process (Step 2) Installation of release film (Step 3) Encapsulation resin supply process (Process 4) Curing process (Step 5) Demolition process of the molded body The following explains the details of each step.

[0082] (Process 1) Semiconductor device preparation process A semiconductor device is an electrical connection between electrode pads on circuit wiring provided on a support and electrodes provided on a semiconductor element. Examples of semiconductor devices include diodes, transistors, capacitors, sensors, integrated circuits, light-emitting elements, photodetectors, and thyristors. Furthermore, the support is a substrate formed in any shape, such as a circular or polygonal shape. Examples of support materials include ceramic substrates, silicone substrates, metal substrates, rigid substrates such as epoxy resin and BT resin, or flexible substrates such as polyimide resin and polyethylene substrates.

[0083] (Step 2) Installation of release film The release film 11 is placed in a lower mold having a cavity recess for supplying the sealing resin. At this time, the release surface 3 of the release film 11 is positioned so that it is in contact with the front side, i.e., with the sealing resin that will be supplied later. Furthermore, the release film 11 is arranged within the cavity recess of the lower mold and along the surface of the flat portion surrounding the cavity recess. At this time, a suction port is provided in the flat portion surrounding the cavity recess to allow the release film 11 to conform to the shape of the cavity recess of the lower mold. Air, moisture, gas, etc. in the space between the release film 11 and the mold are sucked out and discharged from this suction port using a suction device or the like, creating vacuum suction. In addition, in order to firmly fix the release film 11 to the mold, the release film 11 may be clamped by a chuck mechanism positioned at a location corresponding to the outer periphery of the sealing resin injection area, the outer periphery of the entire release film 11, or the outer periphery of the entire mold. Examples of molds include well-known molds and resin molds.

[0084] (Step 3) Encapsulation resin supply process Next, a sealing resin is supplied to the recessed area of ​​the mold where the release film 11 is placed. A known method can be used for supplying the resin. The sealing resin can be any known resin, such as one or a mixture thereof of silicone resins, epoxy resins, acrylic resins, fluororesins, polyimide resins, silicone-modified epoxy resins, and their precursors. In this embodiment, when the release film 11 is applied to a compression molding method, the shape of the sealing resin is preferably in the form of a tablet, granules, sealing granules, or sheet. Inside the mold, the sealing resin is heated to a predetermined temperature and is in a fluid state.

[0085] (Process 4) Curing process Next, the semiconductor device to be molded is attached to the upper mold, which is equipped with a protruding fixing device to hold the outer edge of the object to be molded so that it does not fall. The surface of the semiconductor device with semiconductor elements is placed facing the lower mold, and the mold is pressed against the mold into which the sealing resin is supplied. At this time, the fixing device of the upper mold fits into the groove of the lower mold, and the semiconductor elements are covered with the sealing resin. Subsequently, the sealing resin is heated and pressurized to harden and obtain a molded body. Furthermore, if the encapsulating resin is a precursor of a curable resin, it may be cured by heating and irradiation with active energy rays. Examples of the above-mentioned active energy rays include radiation, ultraviolet light, visible light, and electron beams.

[0086] (Step 5) Demolition process of the molded body Subsequently, the molded body is removed from the mold. In the molded body demolding process, air, moisture, gas, etc., are supplied between the release film 11 and the mold, causing the release film 11 to peel off the mold and the molded body to be demolded. Simultaneously or afterward, the release film 11 separates from the molded body. When there is only one semiconductor element mounted on the support, this molded body becomes a resin-encapsulated semiconductor device. This results in a semiconductor device with a good appearance.

[0087] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0088] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to the descriptions of these examples.

[0089] (1) First resin composition (raw material for release layer) The following raw materials were used as the first resin composition. (raw materials) • Melamine-based release agent: Arakawa Chemical Industries, Ltd., Aracoat, RL3021 (main component) / RA2000 (hardener) (Solid content 10% by mass, solvent: IPA) • Acrylic mold release agent: Tokushiki Co., Ltd., SQ100 (main component) / UAX-615 (hardener) (solid content 10% by mass, solvent: ethyl acetate)

[0090] (2) Base material layer Each base layer was fabricated by extrusion molding using the raw materials listed below, to achieve the thicknesses shown in Table 1. • TPE-1: Polybutylene terephthalate elastomer resin, manufactured by Toray Celanese, Hytrel, 4777 (Shore D hardness: D47) • TPE-2: Polybutylene terephthalate elastomer resin, manufactured by Toray Celanese, Hytrel, 5577 (Shore D hardness: D53) • TPE-3 polybutylene terephthalate elastomer resin: Manufactured by Toray Celanese, Hytrel, 6377 (Shore D hardness: D63) • TPE-4: Polybutylene terephthalate elastomer resin, manufactured by Toray Celanese, Hytrel, 7277 (Shore D hardness: D72) Furthermore, the following films were used directly as the base layer. • OPET: Biaxially oriented polyethylene terephthalate film manufactured by Toray Industries, Inc. (Lumirror® film, 50 μm thick)

[0091] (3) Preparation of release film Using the raw materials described in (1) and (2) above, each release film shown in Table 1 was prepared as follows.

[0092] <Example 1> The melamine-based release agent described in (1) above was applied to the TPE-1 (base layer) prepared in (2) above using a bar coater, and cured at 120°C for 1 minute to obtain a release film having a release layer on the base layer. The thickness of the release layer of the obtained release film was 1 μm.

[0093] <Example 2> A release film was obtained in the same manner as in Example 1, except that TPE-1 was changed to TPE-2 as the base layer.

[0094] <Example 3> The acrylic release agent described in (1) above was applied to the TPE-3 (base layer) prepared in (2) above using a bar coater, and cured at 80°C for 3 minutes / 40°C for 3 days to obtain a release film having a release layer on the base layer. The thickness of the release layer of the obtained release film was 1 μm.

[0095] <Example 4> A release film was obtained in the same manner as in Example 3, except that the substrate thickness was changed to 75 μm.

[0096] <Example 5> A release film was obtained in the same manner as in Example 3, except that TPE-3 was changed to TPE-4 as the base layer.

[0097] <Comparative Example 1> A release film was obtained in the same manner as in Example 3, except that TPE-3 was replaced with OPET as the base layer.

[0098] (4) Measurement and evaluation The following measurements and evaluations were performed using the obtained release film. The results are shown in Table 2.

[0099] (a) In thermomechanical analysis (TMA) measurements, under the conditions of a heating rate of 2°C / min and a load of 500mN, the release film was measured in tensile strength. In the TMA curve obtained from the relationship between the temperature and the dimensional change in the length of the release film, the dimensional change at 140°C was defined as X1 (%), the dimensional change at 160°C was defined as X2 (%), and (X2-X1) / (160-140) was defined as α1.

[0100] (a1) In thermomechanical analysis (TMA) measurements, under the conditions of a heating rate of 2°C / min and a load of 500mN, the release film was measured in tensile strength. From the relationship between the temperature and the dimensional change in the length of the release film, the dimensional change at 25°C was defined as X3 (%), and the dimensional change at 100°C was defined as X4 (%). (X4-X3) / (100-25) was defined as α2, and α1 / α2 was calculated.

[0101] (b) Thermomechanical analysis (TMA) was performed to determine the dimensional change (Y1) of the release film when the temperature was increased from 30°C to 150°C at a rate of 2°C / min, with a tensile load of 500mN.

[0102] (c) When dynamic viscoelasticity (DMA) measurements were taken under the conditions of a heating rate of 5°C / min and a frequency of 1 Hz, the storage modulus (MPa) at 150°C was determined.

[0103] (d) The 5% tensile strength (5% modulus) (MPa) of the release film at 150°C was calculated from the SS curve obtained by measuring in accordance with the tensile test JIS-K7127.

[0104] (e) Let S1 (MPa) be the breaking strength at 25°C, and S2 (MPa) be the breaking strength at 150°C. Measurements were taken in accordance with JIS-K7127. The breaking strength at 150°C was defined as S2 (MPa), and (1 - (S1 - S2) / S1) was defined as β1.

[0105] Thermomechanical analysis (TMA) measurements were performed using a commercially available thermomechanical analyzer (TMA7100 (manufactured by Hitachi High-Tech Science Co., Ltd.)) under the following measurement conditions. (Measurement conditions) Temperature range: 0-200℃ • Heating rate: 2°C / min • Load: 500mN • Test specimen: 4mm wide x 10mm long • Test mode: Tensile

[0106] (5) Evaluation (i) Creation of molded body First, the following granular thermosetting resin composition was prepared as the encapsulating resin. (raw materials) • Epoxy resin 1: Biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000) • Epoxy resin 2: Biphenyl-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YL6677) • Hardener 1: Biphenylene skeleton-containing phenol aralkyl resin (manufactured by Nippon Kayaku Co., Ltd., GPH-65) • Hardener 2: Formaldehyde-modified triphenylmethane-type phenolic resin (Air Water Corporation, HE910-20) • Curing accelerator: Triphenylphosphine (manufactured by Hokko Chemical Industry Co., Ltd., TPP) • Inorganic filler: Molten spherical silica (manufactured by Denki Kagaku Kogyo Co., Ltd., FB-950FC) • Coloring agent: Carbon black (manufactured by Mitsubishi Chemical Corporation, MA-600) • Coupling agent: N-phenyl-γ-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573) • Release agent: Carnauba wax (manufactured by Nikko Fine Co., Ltd., Nikko Carnauba) (procedure) 4.5 parts by mass of epoxy resin 1, 4.5 parts by mass of epoxy resin 2, 2.8 parts by mass of curing agent 1, 2.8 parts by mass of curing agent 2, 0.4 parts by mass of curing accelerator, 84.2 parts by mass of inorganic filler, 0.2 parts by mass of colorant, 0.4 parts by mass of coupling agent, and 0.2 parts by mass of mold release agent were prepared. Next, each raw material component was mixed at room temperature using a mixer, and then roll-kneaded while heating with two rolls at 45°C and 90°C to obtain a kneaded product. Next, the kneaded product was cooled and then pulverized to obtain a granular thermosetting resin composition.

[0107] Next, the thermosetting resin composition was cured (resin-sealed) using each release film in the following procedure. First, five semiconductor elements, each 0.3 mm thick and 7.5 mm square, were bonded to an organic substrate, each 0.4 mm thick, 65 mm wide, and 190 mm long, using silver paste. Gold wires, each 18 μm in diameter and 7 mm long, were then bonded to the substrate at a pitch of 60 μm. Next, the mold temperature of the compression molding machine (TOWA Corporation, PMC1040) was pre-set to 150°C. Then, the organic substrate was fixed to the upper mold so that the side with the semiconductor elements mounted faced the lower mold. Next, the release films prepared in each example and comparative example were placed on the lower mold, and the mold interior space was evacuated to make the release films conform to the mold. After that, the prepared granular thermosetting resin composition (sealing resin composition) was uniformly supplied onto the release film. Next, immediately after supplying the encapsulating resin composition, the mold was clamped until the gap between the organic substrate and the release film was 4 mm. At the same time, the pressure inside the cavity formed by the lower and upper molds was reduced to 0.8 Torr in 4 seconds. Then, while continuing to reduce the pressure, the mold was completely clamped in 12 seconds, and encapsulating molding was performed under conditions of a molding pressure of 3.9 MPa and a curing time of 90 seconds to create a molded body.

[0108] (ii) Evaluation of release film [Type-following ability] In the procedure described above, the degree of air pockets between the mold and the release film when the release film was made to conform to the mold by vacuuming was evaluated according to the following criteria. ◎; No air pockets are generated. ○; There are tiny air pockets, but this does not pose a practical problem. △; There were tiny air pockets, which reduced the vacuum level of the film adsorption. ×; Large air pockets cause poor tracking (or make evaluation impossible).

[0109] [Dimensional stability] In the procedure described above, the appearance of the cured product after releasing it from the molded release film (including wrinkles, etc.) was evaluated according to the following criteria. ○; No wrinkles or deformation, no problems. △; There are some slight wrinkles, but it does not affect its practical use. ×; Large wrinkles and molding defects were present.

[0110] [Table 1] [Explanation of symbols]

[0111] 1 Release layer 2 Base material layer 3 Release surface 11 Release film

Claims

1. A release film that meets the following requirement (a): (a) In thermomechanical analysis (TMA) measurements, under the conditions of a heating rate of 2°C / min and a load of 500 mN, the TMA curve obtained from the relationship between the temperature measured by tensile testing of the release film and the dimensional change in the length of the release film is such that the dimensional change at 140°C is X1 (%), the dimensional change at 160°C is X2 (%), and (X2 - X1) / (160 - 140) is α1, where α1 is between 0.1 and 1.

0.

2. The release film according to claim 1, further satisfying the following requirement (b). (b) Thermomechanical analysis (TMA) shows that when the temperature is increased from 30°C to 150°C at a rate of 2°C / min with a tensile load of 500 mN, the dimensional change (Y1) of the release film is between 4% and 80%.

3. The release film according to claim 1 or 2, further satisfying the following requirement (c). (c) When dynamic viscoelasticity (DMA) is measured under conditions of a heating rate of 5°C / min and a frequency of 1 Hz, the storage modulus at 150°C is 10 MPa to 500 MPa.

4. The release film according to claim 1 or 2, further satisfying the following requirement (d). (d) The release film has a 5% tensile strength (5% modulus) of 0.9 MPa to 3.0 MPa at 150°C.

5. The release film according to claim 1 or 2, further satisfying the following requirement (e). (e) Let S1 (MPa) be the breaking strength at 25°C and S2 (MPa) be the breaking strength at 150°C, and let β1 be (1 - (S1 - S2) / S1), then β1 is between 0.2 and 0.

9.

6. The release film according to claim 1 or 2, having a multilayer structure comprising a release layer which forms at least one surface of the release film, and a base layer made of a material different from the release layer.

7. The release film according to claim 6, wherein the base layer comprises an elastomer.

8. A release film according to claim 1 or 2, for use in a encapsulation process using a thermosetting resin.

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