Mold release film and method for manufacturing semiconductor package

Abstract

A mold release film includes a mold release layer having an elongation at break of 120% or more and an average thickness of 5 [mu] m or more, and a base material layer.

Description

Technical Field

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

[0002] Semiconductor chips are usually sealed with resin to isolate and protect them from the outside air, and are mounted on a substrate as a molded product called a package. In the past, the molded product was molded into a package molded product in which each chip was connected via a flow channel as a flow path for the sealing resin. In this case, the molded product is releasable from the mold by the structure of the mold, adding a release agent to the sealing resin, etc.

[0003] On the other hand, due to the demand for miniaturization and multi-pin packaging, the ball grid array (BGA) method, the quad flat non-leaded (QFN) method, the wafer level chip size package (WL-CSP) method and other packages are increasing. In the QFN method, in order to ensure the stand-off height and prevent the burr of the sealing material from the terminal part, in addition, in the BGA method and the WL-CSP method, in order to improve the demolding property of the package from the mold, a resin release film is used (for example, refer to patent document 1). The molding method using a release film is called "film-assisted molding".

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2002-158242 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Patent Document 1 discloses a mold release film mainly composed of an acrylic resin as a layer responsible for releasability from a molded article. From the viewpoint of mold releasability, it is preferable to use a mold release layer composed of an acrylic resin.

[0009] However, in recent years, the packaging structure has become more complicated, and the precision of the packaging structure is also required. Therefore, sometimes the release film is also required to have properties other than demolding properties. For example, with the complexity of the packaging structure, a part of the release layer is easy to break when the package is peeled off from the release film, and as a result, a part of the release layer that is easy to break is attached to the package (hereinafter also referred to as "release layer residue"). It is expected to reduce the occurrence of such release layer residue.

[0010] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a release film capable of reducing the occurrence of a release layer residue and a method for manufacturing a semiconductor package using the release film.

[0011] Means for solving problems

[0012] The present disclosure includes the following aspects.

[0013] <1> A release film comprises a release layer and a substrate layer, wherein the release layer has an elongation at break greater than or equal to 120%, and an average thickness of the release layer greater than or equal to 5 μm.

[0014] <2> like <1> The release film, wherein the release layer comprises polyurethane resin.

[0015] <3> A release film comprises a release layer and a base layer, wherein the release layer comprises a polyurethane resin, and the polyurethane resin comprises a structural unit 1 having an alkylene oxide skeleton.

[0016] <4> like <1> ~ <3> The release film according to any one of the preceding claims, wherein the substrate layer is a polyester film.

[0017] <5> like <2> In the release film, the polyurethane resin comprises a structural unit 1 having an alkylene oxide skeleton.

[0018] <6> like <3> or <5> In the release film, the structural unit 1 includes at least one of a structural unit 2 having an ethylene oxide skeleton and a structural unit 3 having a propylene oxide skeleton.

[0019] <7> like <3> , <5> and <6> The release film according to any one of the preceding claims, wherein the polyurethane resin further comprises a structural unit 4 having urethane bonds at both ends of a divalent linking group, and the total content of the structural unit 2 and the structural unit 3 is greater than or equal to 50 mol % relative to the total of the structural unit 1 and the structural unit 4.

[0020] <8> like <3> , <5> , <6> and <7> The release film according to any one of the preceding claims, wherein the structural unit 1 includes the structural unit 2 and the structural unit 3, and the ratio of the structural unit 2 to the structural unit 3, that is, the structural unit 2:structural unit 3, is 10:90 to 60:40.

[0021] <9> like <2> , <3> and <5> ~ <8> The release film according to any one of the preceding claims, wherein the polyurethane resin comprises a structural unit 4 having urethane bonds at both ends of a divalent linking group, wherein the divalent linking group is hexamethylene, 2,2,4-trimethylhexamethylene, 2,4,4-trimethylhexamethylene, pentamethylene or tetramethylene.

[0022] <10> like <1> to <9> The mold release film according to any one of the preceding claims, wherein the mold release film is used for transfer molding or compression molding.

[0023] <11> A method for manufacturing a semiconductor package, comprising: using <1> to <10> The release film described above is used for transfer molding or compression molding.

[0024] Effects of the Invention

[0025] According to the present disclosure, it is possible to provide a release film capable of reducing the occurrence of a release layer residue and a method for manufacturing a semiconductor package using the release film. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [ Figure 1 ] is a diagram showing a test piece used for measuring the elongation at break (%) of the release layer. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0028] In the present disclosure, in a numerical range expressed using “to”, the numerical values ​​described before and after “to” are included as the minimum value and the maximum value, respectively.

[0029] In the numerical range recorded in stages in the present disclosure, the upper limit or lower limit recorded in one numerical range can also be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical range recorded in the present disclosure, the upper limit or lower limit of the numerical range can also be replaced by the value shown in the embodiment.

[0030] In the present disclosure, each component may include a plurality of corresponding substances. When a plurality of substances corresponding to each component are present in the composition, the content or content of each component refers to the total content or content of the plurality of substances present in the composition unless otherwise specified.

[0031] In the present disclosure, the word "layer" includes not only a case where the layer is formed in the entire region when the region where the layer exists is observed, but also a case where the layer is formed only in a part of the region.

[0032] In the present disclosure, the average thickness of a layer or a film (also referred to as the average value of thickness) is a value obtained by measuring the thickness at five points of the target layer or film and giving the measured thickness as the arithmetic average value.

[0033] The thickness of a layer or film can be measured using a micrometer or the like. In the present disclosure, when the thickness of a layer or film can be directly measured, the thickness is measured using a micrometer. On the other hand, when measuring the thickness of one layer or the total thickness of multiple layers, the thickness can be measured by observing the cross section of the film using an electron microscope.

[0034] Hereinafter, regarding the release film of the present disclosure, the release film of the first embodiment and the release film of the second embodiment will be described. In addition, the release film of the present disclosure is not limited to the following first embodiment and second embodiment. In addition, the configurations that can be adopted in the first embodiment and the second embodiment can also be appropriately combined.

[0035] [First embodiment]

[0036] <Release film>

[0037] The release film in the first embodiment of the present disclosure includes a release layer and a substrate layer, wherein the release layer has an elongation at break of 120% or more and an average thickness of 5 μm or more. The release layer has an elongation at break of 120% or more.

[0038] The release film of the first embodiment can reduce the occurrence of release layer residue by adopting the above-mentioned configuration. The reason is not clear, but is presumed as follows.

[0039] In the release film disclosed herein, the release layer has an elongation at break of 120% or more and an average thickness of 5 μm or more, so that the release layer has excellent stretchability, and a portion of the release layer is not easily broken when the semiconductor package is peeled off. As a result, a portion of the release layer is not easily attached to the semiconductor package, and the occurrence of release layer residue can be reduced.

[0040] The mold release film of the present disclosure is preferably used for semiconductor molding. More specifically, it is preferably used when manufacturing a semiconductor package using a sealing material in a state where the base material layer is brought into contact with a mold used for resin molding of a semiconductor package and the mold release layer is located on the semiconductor chip side to be molded.

[0041] [Mold release layer]

[0042] The release film of the present disclosure includes a release layer. The structure of the release layer is not particularly limited as long as the elongation at break is 120% or more and the average thickness is 5 μm or more.

[0043] (Elongation at break of release layer)

[0044] The elongation at break of the release layer is greater than or equal to 120%, preferably greater than or equal to 150%, and more preferably greater than or equal to 180%. The elongation at break of the release layer can be adjusted, for example, by the composition of the resin component constituting the release layer, the amount of the cross-linking agent described later, etc. The upper limit of the elongation at break of the release layer is not particularly limited, and for example, it may be less than or equal to 800%, less than or equal to 500%, or less than or equal to 300%.

[0045] The breaking elongation (%) of the release layer is determined as follows. First, a release film is used to prepare a Figure 1 Test pieces of the shape shown. Figure 1 The unit of the numerical value is mm. The two ends of the test piece are clamped by a testing machine to perform a tensile test. The measurement is carried out at 170°C and the tensile speed is 200 mm / min. Based on the distance A between the points of the sample before the test ( Figure 1 The elongation at break of the release layer was calculated from the length of the portion of the test piece with a width of 10 mm (40 mm) and the distance B between the marks when the release layer was broken by the following formula.

[0046] [Number 1]

[0047]

[0048] The breaking elongation of the release layer of the release film may be measured by, for example, using "Tensilon tensile tester RTA-100" manufactured by Orientec Corporation, "Tensilon universal tester RTG-1210" manufactured by A&D Corporation, or similar testing machines having a clamping tool.

[0049] (Average thickness of release layer)

[0050] The average thickness of the release layer is greater than or equal to 5 μm, and may be 5 μm to 40 μm, or 5 μm to 30 μm.

[0051] The release layer may contain a resin component. The resin component of the release layer is not particularly limited, and examples thereof include polyurethane resins, acrylic resins, silicone resins, etc. In particular, from the viewpoint of excellent elongation at break of the release layer, the release layer preferably contains a polyurethane resin.

[0052] In the present disclosure, the polyurethane resin is preferably a resin component having a urethane bond in the main chain of the resin, and more preferably a resin component having a plurality of structural units containing a urethane bond in the main chain of the resin.

[0053] The release layer may contain only one resin component or may contain two or more resin components. For example, the release layer may be a layer containing only polyurethane resin as a resin component, or may be a layer containing two types of polyurethane resin and acrylic resin, or two types of polyurethane resin and silicone resin as resin components.

[0054] The release layer may contain a cross-linked polyurethane resin as the polyurethane resin or a cross-linked acrylic resin as the acrylic resin. From the viewpoint of reducing the occurrence of release layer residue and balancing the release properties, the release layer preferably contains a cross-linked polyurethane resin as the polyurethane resin.

[0055] In the present disclosure, the cross-linked polyurethane resin refers to a polyurethane resin cross-linked by a cross-linking agent, and the cross-linked acrylic resin refers to a acrylic resin cross-linked by a cross-linking agent.

[0056] The polyurethane resin may be a resin obtained by reacting a polyol compound having multiple hydroxyl groups with a polyisocyanate compound having multiple isocyanate groups. The polyurethane resin may include a compound having multiple urethane bonds in the main chain, or a compound having multiple urethane bonds in the main chain and a hydroxyl group at at least one of the two ends of the main chain.

[0057] The polyurethane resin preferably contains a structural unit 1 having an alkylene oxide skeleton. The polyurethane resin may contain a plurality of structural units 1. The polyurethane resin may contain only one structural unit 1, or may contain two or more structural units 1. When the polyurethane resin contains a plurality of two or more structural units 1, the polyurethane resin may be a block polymer of the structural unit 1, or may be a random polymer of the structural unit 1.

[0058] The structural unit 1 having an alkylene oxide skeleton preferably includes at least one of the structural unit 2 having an ethylene oxide skeleton and the structural unit 3 having a propylene oxide skeleton, and preferably includes both the structural unit 2 and the structural unit 3 .

[0059] The total content of the structural unit 2 and the structural unit 3 may be 50 mol% or more, 80 mol% to 100 mol%, or 90 mol% to 100 mol%, relative to the total amount of the structural unit 1.

[0060] In the present disclosure, the content of each structural unit can be expressed by, for example 1 It was calculated by H NMR measurement.

[0061] The structural unit 1 includes the structural unit 2 and the structural unit 3. The ratio of the structural unit 2 to the structural unit 3 (structural unit 2:structural unit 3) may be 10:90 to 60:40, 10:90 to 55:45, or 15:85 to 50:50.

[0062] The polyurethane resin preferably further comprises a structural unit 4 having a carbamate bond at both ends of a divalent linking group (i.e., *-carbamate bond-divalent linking group-carbamate bond-* represents a bonding position). The polyurethane resin more preferably comprises a structural unit 1 having an alkylene oxide skeleton together with the structural unit 4, and further preferably comprises both a structural unit 2 having an ethylene oxide skeleton and a structural unit 3 having a propylene oxide skeleton.

[0063] The polyurethane resin further comprises structural unit 4, and the total content of structural unit 2 and structural unit 3 relative to the total of structural unit 1 and structural unit 4 may be greater than or equal to 50 mol%, may be 80 mol% to 99.5 mol%, may be 90 mol% to 99 mol%, or may be 95 mol% to 99 mol%.

[0064] The divalent linking group contained in the structural unit 4 is preferably a substituted or unsubstituted hydrocarbon group, more preferably a linear or branched hydrocarbon group without a ring structure. The divalent linking group may have 2 to 20 carbon atoms, 3 to 15 carbon atoms, or 4 to 10 carbon atoms.

[0065] Examples of the divalent linking group contained in the structural unit 4 include a hexamethylene group, a 2,2,4-trimethylhexamethylene group, a 2,4,4-trimethylhexamethylene group, a pentamethylene group, and a tetramethylene group.

[0066] The structural unit 4 may be a structural unit derived from a diisocyanate compound, or may be a structural unit derived from hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, pentamethylene diisocyanate, or tetramethylene diisocyanate.

[0067] The content of the structural unit 4 may be less than or equal to 50 mol %, 0.5 mol % to 20 mol %, 1 mol % to 10 mol %, or 1 mol % to 5 mol % relative to all structural units contained in the polyurethane resin.

[0068] The acrylic resin is preferably an acrylic copolymer obtained by copolymerizing a low glass transition temperature (Tg) monomer such as butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate as a main monomer with a functional group monomer such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, 4-hydroxybutyl acrylate, acrylamide, and acrylonitrile.

[0069] It can be confirmed by IR measurement, NMR measurement, or the like that the resin component contains a polyurethane resin, an acrylic resin, or the like.

[0070] Examples of the crosslinking agent used in the production of the crosslinked polyurethane resin or the crosslinked acrylic resin include known crosslinking agents such as isocyanate compounds, melamine compounds, and epoxy compounds. Among them, isocyanate compounds are preferred.

[0071] The cross-linked polyurethane resin or cross-linked acrylic resin produced using the cross-linking agent described above has a network structure that expands gently. Therefore, when the above resin is used as the resin component of the release layer, the stretchability of the release layer is improved, and the hindrance to the stretchability of the substrate layer can be suppressed. As a result, there is a tendency that the followability of the release film to the mold is improved.

[0072] From the viewpoint of the balance between the elongation at break of the release layer and the followability of the release film to the mold, the crosslinking agent is preferably a bifunctional to tetrafunctional multifunctional crosslinking agent, and more preferably a bifunctional or trifunctional multifunctional crosslinking agent. As the above-mentioned multifunctional crosslinking agent, a bifunctional or trifunctional isocyanate compound is preferred. As the bifunctional or trifunctional isocyanate compound, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,6-hexane diisocyanate, etc. can be cited.

[0073] The crosslinked polyurethane resin preferably has a urethane bond in the main chain and a urethane bond in the side chain that crosslinks the main chains, and more preferably has a plurality of urethane bonds in the main chain and a urethane bond in the side chain that crosslinks the main chains.

[0074] From the viewpoint of excellent elongation at break of the release layer and excellent followability of the release film to the mold, the resin component preferably contains a cross-linked polyurethane resin. Furthermore, the content of the cross-linked polyurethane resin relative to the entire resin component may be 50% to 100% by mass, 70% to 100% by mass, or 90% to 100% by mass.

[0075] The amount of the crosslinking agent used in the production of a crosslinked polyurethane resin or a crosslinked acrylic resin (preferably the production of a crosslinked polyurethane resin) can be 10 to 50 parts by mass, or 15 to 40 parts by mass, relative to 100 parts by mass of the resin to be crosslinked. From the viewpoint of releasability from a semiconductor package, it can be 20 to 30 parts by mass.

[0076] When the release layer contains a resin component, the content of the resin component may be 50 to 100 mass %, 80 to 100 mass %, or 90 to 100 mass % relative to the entire release layer.

[0077] (Other ingredients)

[0078] The release layer may further contain other components other than the resin component, such as a solvent, an anchor enhancer, a crosslinking accelerator, an antistatic agent, a colorant, and inorganic particles, as necessary, as long as the effects of the present invention are exhibited.

[0079] [Base material layer]

[0080] The release film disclosed herein includes a substrate layer. The substrate layer is not particularly limited and can be appropriately selected from resin-containing substrate layers used in the technical field. From the viewpoint of improving the followability to the mold shape, it is preferred to use a resin-containing substrate layer with excellent stretchability.

[0081] Considering that the molding of the sealing material is carried out at a high temperature (about 100°C to 200°C), the base material layer preferably has a heat resistance greater than or equal to this temperature. In addition, from the viewpoint of suppressing wrinkles of the sealing resin and rupture of the release film when the release film is attached to the mold and when the resin flows during molding, it is preferred to select the material of the base material layer in consideration of the elastic modulus and elongation at high temperature.

[0082] From the viewpoint of heat resistance and elastic modulus at high temperature, the material of the substrate layer is preferably a polyester resin. Examples of the polyester resin include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, and copolymers and modified resins thereof.

[0083] The substrate layer is preferably formed of a polyester resin in a sheet shape, and more preferably a polyester film. From the viewpoint of mold followability, a biaxially stretched polyester film is preferred.

[0084] The average thickness of the substrate layer is not particularly limited, but is preferably 5 μm to 300 μm, more preferably 10 μm to 200 μm, and further preferably 20 μm to 100 μm. When the average thickness is greater than or equal to 5 μm, there is a tendency that the workability is excellent and wrinkles are not easily generated. When the average thickness is less than or equal to 300 μm, the mold followability is excellent during molding, so there is a tendency that wrinkles, etc. can be suppressed in the molded semiconductor package.

[0085] [other]

[0086] The substrate layer is a layer located on the surface side of the mold. Depending on the material used, a greater peeling force is sometimes required to peel the release film from the mold. In the case where a material that is difficult to peel off from the mold is used for the substrate layer, it is preferably adjusted in a manner that makes it easy to peel the release film from the mold. For example, in order to improve the releasability from the mold, the surface of the substrate layer opposite to the release layer in contact with the release layer, that is, the surface of the substrate layer on the mold side, may be subjected to surface processing such as pear skin processing, or another release layer (second release layer) may be newly provided. As a material for the second release layer, there is no particular limitation as long as it satisfies heat resistance, peelability from the mold, etc., and the same material as the release layer can be used. The average thickness of the second release layer is not particularly limited and can be 0.1μm to 100μm.

[0087] In addition, the release layer or the anchoring enhancement layer of the second release layer, the antistatic layer, the colored layer, etc. may be provided between the release layer and the substrate layer, between the substrate layer and the second release layer, etc. as needed. As a preferred layer structure, a three-layer structure in which a substrate layer, an antistatic layer and a release layer are provided in sequence may be cited. The antistatic layer may include antistatic polymers such as polymers containing quaternary ammonium salts and polythiophene-based polymers.

[0088] From the viewpoint of mold followability, the total thickness of the release film is preferably 350 μm or less, more preferably 200 μm or less. From the viewpoint of workability, the total thickness of the release film is preferably 10 μm or more, more preferably 20 μm or more.

[0089] [Second embodiment]

[0090] <Release film>

[0091] The release film in the second embodiment of the present disclosure includes a release layer and a base material layer. The release layer includes a polyurethane resin including the structural unit 1 having an alkylene oxide skeleton.

[0092] The release film of the second embodiment can reduce the occurrence of release layer residue by adopting the above-mentioned configuration. The reason is not clear, but is presumed as follows.

[0093] In the release film disclosed herein, the release layer includes a polyurethane resin, and the polyurethane resin includes a structural unit 1 having an alkylene oxide skeleton, thereby having excellent stretchability, and a part of the release layer is not easily broken when the semiconductor package is peeled off. As a result, a part of the release layer is not easily attached to the semiconductor package, and the occurrence of residual release layer can be reduced.

[0094] [Method for producing release film]

[0095] The release film of the present disclosure can be manufactured by a known method. For example, the release film of the present disclosure can be manufactured by applying a release layer forming composition to one side of the substrate layer and drying it. The release layer forming composition can contain a resin component and other components added as needed. For example, the release layer forming composition can contain a polyurethane resin, a crosslinking agent, and other components as needed.

[0096] [Preparation of Release Layer Forming Composition]

[0097] The method for preparing the release layer forming composition is not particularly limited, and examples thereof include a method of dispersing or dissolving a resin component in a solvent, and the release layer forming composition can be prepared using a known composition preparation method.

[0098] The solvent used in the preparation of the release layer forming composition is not particularly limited, but is preferably an organic solvent capable of dissolving or dispersing the resin component, etc. Examples of the organic solvent include toluene, methyl ethyl ketone, and ethyl acetate.

[0099] [Giving and drying]

[0100] The method for applying the release layer forming composition to one side of the substrate layer is not particularly limited, and known coating methods such as roll coating, rod coating, and kiss coating can be used. When applying the release layer forming composition, it is preferably applied in such a manner that the average thickness of the composition layer (release layer) after drying becomes greater than or equal to 5 μm.

[0101] The method for drying the applied release layer-forming composition is not particularly limited, and a known drying method can be used. For example, the method may be a method of drying at 50° C. to 150° C. for 0.1 minute to 60 minutes.

[0102] When the composition for forming a release layer contains a polyurethane resin and a crosslinking agent, a crosslinking reaction between the polyurethane resin and the crosslinking agent can be advanced by drying treatment to form a release layer containing a crosslinked polyurethane resin.

[0103] [use]

[0104] The release film disclosed herein can be used for molding of semiconductor packages, and can be suitably used for transfer molding or compression molding.

[0105] <Method for manufacturing semiconductor package>

[0106] The method for manufacturing a semiconductor package of the present disclosure includes: performing transfer molding or compression molding using the release film of the present disclosure.

[0107] In transfer molding, for example, a semiconductor chip is placed in a mold of a transfer molding device, and a release film is placed in another mold, and the release film is made to follow the shape of the mold by vacuum adsorption. Next, the mold is closed, and a molten thermosetting sealing material (such as epoxy resin) is injected into the heated mold by the transfer method, and the sealing material is cured to form a semiconductor package. Then, the mold is opened and the molded semiconductor package is taken out.

[0108] In compression molding, for example, a release film is placed in the mold of a compression molding device, and the release film is made to follow the shape of the mold by vacuum adsorption. Next, a thermosetting sealing material (such as epoxy resin, etc.) for the semiconductor package is injected into the mold, a semiconductor chip is placed on it, and the mold is compressed while being heated, thereby curing the sealing material and molding the semiconductor package. Then, the mold is opened and the molded semiconductor package is taken out.

[0109] In the manufacturing method of the semiconductor package disclosed in the present invention, the release film disclosed in the present invention is used. Therefore, when the molded semiconductor package is peeled off from the release film to remove the semiconductor package, a part of the release layer is not easy to break. As a result, a part of the release layer is not easy to adhere to the semiconductor package, which can reduce the occurrence of release layer residue.

[0110] Example

[0111] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[0112] (Synthesis of acrylic resin)

[0113] The acrylic resin was synthesized by copolymerizing the monomers shown in the following Table 1 in the blending amounts (parts by mass) shown in Table 1 by solution polymerization. In Table 1, BA is butyl acrylate, and 4-HBA is 4-hydroxybutyl acrylate.

[0114] The number average molecular weight Mn and the weight average molecular weight Mw of the obtained acrylic resin were measured by gel permeation chromatography (GPC) based on standard polystyrene.

[0115] Table 1 shows Mn and Mw of the obtained acrylic resin.

[0116] [Table 1]

[0117] Acrylic resin BA 92 4-HBA 8 Mn 144,000 M 854,000

[0118] <Example 1>

[0119] 100 parts by mass of a polyurethane resin (Lion Specialty Chemicals Co., Ltd.: US-1353H) and a toluene solution having a solid content of 15% by mass prepared by adding 20 parts by mass of Coronate L (Tosoh Corporation, trade name) as a crosslinking agent to toluene were mixed to prepare a release layer-forming composition. A biaxially stretched polyethylene terephthalate film (Unitika Co., Ltd.: S-38) having an average thickness of 38 μm and subjected to corona treatment was used as a substrate layer. Subsequently, the release layer-forming composition was applied to one side of the substrate layer using a roll coater so that the average thickness after drying was 5 μm and dried to form a release layer, thereby obtaining a release film.

[0120] <Example 2>

[0121] A release film was produced in the same manner as in Example 1 except that the average thickness of the release layer after drying was 10 μm.

[0122] <Example 3>

[0123] A release film was produced in the same manner as in Example 1 except that the average thickness of the release layer after drying was 25 μm.

[0124] <Example 4>

[0125] A release film was produced in the same manner as in Example 2 except that the amount of the cross-linking agent was changed to 40 parts by mass based on 100 parts by mass of the polyurethane resin.

[0126] <Example 5>

[0127] A release film was produced in the same manner as in Example 4 except that the average thickness of the release layer after drying was 15 μm.

[0128] <Comparative Example 1>

[0129] A release film was produced in the same manner as in Example 3 except that 100 parts by mass of the synthesized acrylic resin was used instead of 100 parts by mass of the polyurethane resin and the cross-linking agent was changed to 10 parts by mass.

[0130] <Comparative Example 2>

[0131] A release film was produced in the same manner as in Example 2 except that 100 parts by mass of the synthesized acrylic resin was used instead of 100 parts by mass of the polyurethane resin.

[0132] <Comparative Example 3>

[0133] A release film was produced in the same manner as in Comparative Example 2 except that the average thickness of the release layer after drying was 20 μm.

[0134] <Comparative Example 4>

[0135] A release film was produced in the same manner as in Comparative Example 2 except that the average thickness of the release layer after drying was 25 μm.

[0136] (Elongation at break of release layer)

[0137] The elongation at break of the release layer at 170° C. was measured by the above method. The measurement was performed using “Tensilon Tensile Tester RTA-100 Model” manufactured by ORIENTEC CORPORATION. The results are shown in Table 2.

[0138] (Evaluation of EMC's mold release properties)

[0139] The mold release property with respect to epoxy molding compound (EMC) as a sealing material was evaluated as follows.

[0140] The release layer of the release film was placed in contact with a sealing material (Showa Denko Materials Co., Ltd.: trade name "CEL-9750ZHF10") and subjected to heat and pressure treatment at a temperature of 175°C, a pressure of 6 KPa, and a treatment time of 4 minutes.

[0141] As an index of the releasability of the release film and the sealing material after the heat and pressure treatment, the peeling force when the peeling test is performed at a peeling angle of 180° and a peeling speed of 1000 mm / min is measured. Based on the value of the peeling force obtained by the measurement, the releasability is evaluated according to the following criteria. The results are shown in Table 2. If it is evaluated A or B, the releasability is good.

[0142] -Evaluation Criteria-

[0143] A: less than 150mN / 50mm

[0144] B: greater than or equal to 150mN / 50mm and less than 250mN / 50mm

[0145] C: greater than or equal to 250mN / 50mm

[0146] (Whether there is any release layer remaining)

[0147] A SUS plate (5 mm in width and 0.6 mm in thickness) was placed in contact with the substrate layer side of the release film. A SUS plate (50 mm in width and 0.6 mm in thickness) was placed on the release layer side and subjected to heat and pressure treatment at 170° C. and 32 MPa for 5 minutes.

[0148] After the heating and pressing treatment, the release film was peeled off from the SUS plate on the release layer side. Then, the presence or absence of the release layer remaining on the SUS plate arranged on the release layer side was observed visually and with a "digital microscope VHX-7000" (20 times) manufactured by KEYENCE Co., Ltd., and evaluated according to the following criteria. The results are shown in Table 2.

[0149] A: No release layer residue was observed visually or under a microscope.

[0150] B: Remaining of the release layer was observed by at least either visual observation or microscopic observation.

[0151] [Table 2]

[0152]

[0153] As shown in Table 2, in Examples 1 to 5, the mold release layer was not confirmed to remain on the SUS plate. On the other hand, in Comparative Examples 1 to 4, the mold release layer was confirmed to remain on the SUS plate.

[0154] <Example 6>

[0155] A synthetic polyurethane resin 1 containing a structural unit having a propylene oxide skeleton (PO), a structural unit having an ethylene oxide skeleton (EO), and a structural unit derived from hexamethylene diisocyanate (HDI) at a molar ratio shown in Table 3 was prepared. The molar ratio of each structural unit in the synthetic polyurethane resin 1 was determined by 1 The value calculated from the peak area ratio of HNMR. 1 The peaks of H NMR are related to those from solvents, other components, etc. 1 Since the peaks of H NMR are partially repeated, peaks that are as non-repeating as possible are selected to calculate the molar ratio of each structural unit.

[0156] 100 parts by mass of the synthetic polyurethane resin 1 and a toluene solution having a solid content of 15% by mass prepared by adding 20 parts by mass of Coronate L (trade name of Tosoh Corporation) as a crosslinking agent to toluene were mixed to prepare a release layer-forming composition. A biaxially stretched polyethylene terephthalate film (Unitika Co., Ltd.: S-38) having an average thickness of 38 μm and subjected to corona treatment was used as a substrate layer. Subsequently, the release layer-forming composition was applied to one side of the substrate layer using a roll coater in such a manner that the average thickness after drying was 5 μm and dried to form a release layer, thereby obtaining a release film.

[0157] <Example 7>

[0158] A release film was produced in the same manner as in Example 1 except that the average thickness of the release layer after drying was 10 μm.

[0159] <Example 8>

[0160] A release film was produced in the same manner as in Example 1 except that the average thickness of the release layer after drying was 25 μm.

[0161] <Example 9>

[0162] A release film was prepared in the same manner as in Example 7 except that the amount of the cross-linking agent was changed to 40 parts by mass based on 100 parts by mass of the polyurethane resin.

[0163] <Example 10>

[0164] A release film was produced in the same manner as in Example 9 except that the average thickness of the release layer after drying was 15 μm.

[0165] <Example 11>

[0166] A synthetic polyurethane resin 2 containing a structural unit having a propylene oxide skeleton (PO), a structural unit having an ethylene oxide skeleton (EO), and a structural unit derived from hexamethylene diisocyanate (HDI) at a molar ratio shown in Table 3 was prepared. The molar ratio of each structural unit in the synthetic polyurethane resin 2 is given by 1 The value calculated from the peak area ratio of HNMR. 1 The peaks of H NMR are related to those from solvents, other components, etc. 1 Since the peaks of H NMR are partially repeated, peaks that are as non-repeating as possible are selected to calculate the molar ratio of each structural unit.

[0167] 100 parts by mass of the synthetic polyurethane resin 2 was mixed with a toluene solution having a solid content of 15% by mass prepared by adding 10 parts by mass of CORONATE L (trade name of Tosoh Corporation) as a crosslinking agent to toluene to prepare a release layer forming composition. A biaxially stretched polyethylene terephthalate film (Unitika Co., Ltd.: S-38) having an average thickness of 38 μm and subjected to corona treatment was used as a substrate layer. Subsequently, the release layer forming composition was applied to one side of the substrate layer using a roll coater in a manner such that the average thickness after drying was 15 μm and dried to form a release layer, thereby obtaining a release film.

[0168] <Example 12>

[0169] A release film was prepared in the same manner as in Example 11 except that the amount of the cross-linking agent was changed to 20 parts by mass based on 100 parts by mass of the polyurethane resin.

[0170] <Example 13>

[0171] A release film was produced in the same manner as in Example 11 except that the average thickness of the release layer after drying was 25 μm.

[0172] The release films of Examples 6 to 13 were evaluated for the elongation at break of the release layer, the releasability to EMC, and the release layer residue in the same manner as in the release films of Examples 1 to 5. The results are shown in Table 4.

[0173] [Table 3]

[0174] Synthetic polyurethane resin 1 Synthetic polyurethane resin 2 PO 55 45 EO 10 40 HDI 1 1 Number average molecular weight Mn 12,000 3,400 Weight average molecular weight Mw 190,000 89,000

[0175] [Table 4]

[0176]

[0177] As shown in Table 4, in Examples 6 to 13, no release layer residue was observed on the SUS plate.

[0178] The entire disclosure of Japanese Patent Application No. 2022-146410 filed on September 14, 2022 is incorporated into this specification by reference.

[0179] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A release film comprising a release layer and a substrate layer, wherein the release layer has an elongation at break greater than or equal to 120%, and an average thickness of the release layer greater than or equal to 5 μm.

2. The release film according to claim 1, wherein The release layer includes a polyurethane resin.

3. A release film comprising a release layer and a base layer, wherein the release layer comprises a polyurethane resin, and the polyurethane resin comprises a structural unit 1 having an alkylene oxide skeleton.

4. The release film according to any one of claims 1 to 3, wherein The substrate layer is a polyester film.

5. The release film according to claim 2, wherein The polyurethane resin includes a structural unit 1 having an alkylene oxide skeleton.

6. The release film according to claim 3 or 5, wherein The structural unit 1 includes at least one of a structural unit 2 having an ethylene oxide skeleton and a structural unit 3 having a propylene oxide skeleton.

7. The release film according to any one of claims 3, 5 and 6, wherein The polyurethane resin further includes a structural unit 4 having urethane bonds at both ends of a divalent linking group, wherein the total content of the structural unit 2 and the structural unit 3 is greater than or equal to 50 mol % relative to the total of the structural unit 1 and the structural unit 4.

8. The release film according to any one of claims 3, 5, 6 and 7, wherein The structural unit 1 includes the structural unit 2 and the structural unit 3, and the ratio of the structural unit 2 to the structural unit 3, that is, the structural unit 2: the structural unit 3, is 10:90 to 60:

40.

9. The release film according to any one of claims 2, 3, and 5 to 8, wherein The polyurethane resin includes a structural unit 4 having urethane bonds at both ends of a divalent connecting group, wherein the divalent connecting group is hexamethylene, 2,2,4-trimethylhexamethylene, 2,4,4-trimethylhexamethylene, pentamethylene or tetramethylene.

10. The release film according to any one of claims 1 to 9, wherein The release film is used for transfer molding or compression molding.

11. A method for manufacturing a semiconductor package, comprising: Transfer molding or compression molding is performed using the release film according to any one of claims 1 to 10.

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