Laminated film

Abstract

The present invention relates to a laminated film comprising a substrate and a functional layer disposed on one surface of the substrate, wherein the substrate contains a fluororesin, and the arithmetic average roughness Ra of the other surface of the substrate is 0.3-1.9 μm.

Description

Laminated film

[0001] This invention relates to a laminated film.

[0002] Semiconductor packages have a resin encapsulation section to protect the semiconductor elements, and curable resins such as thermosetting epoxy resins are widely used to form the resin encapsulation section. As a method for encapsulating semiconductor elements, the so-called compression molding method or transfer molding method is known, in which a substrate on which semiconductor elements are mounted is placed in the cavity of a mold, and the cavity is filled with curable resin to form the resin encapsulation section. In these encapsulation methods, the so-called Film-Assisted Molding (FAM) method is usually employed, in which a release film is placed on the cavity surface of the mold to prevent the resin encapsulation section from sticking to the mold.

[0003] Patent Document 1 describes a release film for semiconductor device manufacturing, in which the main surface requiring release properties is modified.

[0004] International Publication No. 2016 / 125796

[0005] However, with the film described in Patent Document 1, when stored or distributed in a wound roll state, the modified side of the film and the other side sometimes come into contact with each other, becoming tightly bound and difficult to peel apart (blocking).

[0006] Furthermore, in the case of the film described in Patent Document 1, the condition of the film surface sometimes changed when it was stored in a wound roll state.

[0007] The present invention aims to provide a laminated film that is less prone to blocking at the contact surfaces between films and less prone to changes in the film surface.

[0008] The present invention relates to the following laminated films: [1] A laminated film comprising a substrate and a functional layer provided on one side of the substrate, wherein the substrate contains a fluororesin and the arithmetic mean roughness Ra of the other side of the substrate is 0.3 to 1.9 μm. [2] The laminated film according to [1], wherein the substrate contains a fluoroolefin polymer. [3] The laminated film according to [1] or [2], wherein the outermost surface of the functional layer contains at least one resin selected from acrylic resin, urethane resin, polyester resin, and epoxy resin. [4] The laminated film according to any one of [1] to [3], wherein the functional layer has a release layer. [5] The laminated film according to any one of [1] to [3], wherein the functional layer has an antistatic layer. [6] The laminated film according to any one of [1] to [3], wherein the functional layer has an antistatic layer and a release layer. [7] The dry coating amount of the functional layer is 0.01 to 20 g / m ２ A laminated film according to any one of [1] to [6]. [8] A laminated film according to any one of [1] to [7] used as a release film. [9] A laminated film according to any one of [1] to [8] used in the manufacture of semiconductor packages.

[0009] According to the present invention, a laminated film can be provided in which blocking is less likely to occur at the contact surfaces between films, and in which the film surface is less likely to change.

[0010] Figure 1 is a cross-sectional view of the laminated film according to this embodiment. Figure 2 is a cross-sectional view of the laminated film according to this embodiment.

[0011] Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments. In the present invention, the numerical range indicated using "~" includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the present invention, the arithmetic mean roughness Ra is measured in accordance with JIS B0601:2013 (ISO 4287:1997, Amd.1:2009). A surface roughness measuring instrument is used for measurement, and the ambient temperature is 23 to 25°C.

[0012] <Laminated Film> A laminated film according to an embodiment of the present invention (hereinafter also referred to as "this laminated film") comprises a base material and a functional layer provided on one side of the base material, wherein the base material contains a fluororesin and the arithmetic mean roughness Ra of the other side of the base material is 0.3 to 1.9 μm.

[0013] By having a Ra of 0.3 to 1.9 μm on the other side of the substrate, i.e., the side opposite to the side with the functional layer, a laminated film can be obtained in which blocking is less likely to occur at the contact surfaces between the films and the film surface is less likely to change. Furthermore, because the substrate contains fluororesin, the release properties from the mold after sealing are excellent, resulting in a laminated film suitable for release films. The laminated film may be in the form of a single sheet or a roll.

[0014] An example of the structure of this laminated film will be explained using the drawings. Figures 1 and 2 are schematic cross-sectional views showing an example of this laminated film.

[0015] The laminated film 10 shown in Figure 1 is an example having a base material 1 and a functional layer 2 provided on one surface of the base material (hereinafter also referred to as the "first surface of the base material") 1A. In the laminated film 10, the Ra of the other surface of the base material (hereinafter also referred to as the "second surface of the base material") 1B is within the specific range described above.

[0016] The laminated film 10 shown in Figure 2 comprises a base material 1 and a functional layer 2 provided on one surface (first surface of the base material) 1A of the base material, and the functional layer 2 is an example in which an antistatic layer 3 and a release layer 4 are provided.

[0017] Furthermore, this laminated film may have other layers between the substrate and the functional layer.

[0018] (Base material) In this laminated film, the base material contains a fluororesin. Since the fluororesin has release properties, a laminated film suitable for release films can be obtained. Furthermore, since the fluororesin is a crystalline thermoplastic resin, it is preferable from the viewpoint of having excellent heat resistance, strength, storage modulus, tensile elongation and other mechanical properties when used at the mold temperature during sealing (for example, 180°C).

[0019] As a fluororesin, fluoroolefin polymers are preferred due to their excellent release properties and heat resistance. A fluoroolefin polymer is a polymer having units based on fluoroolefin. A fluoroolefin polymer may further have other units besides those based on fluoroolefin.

[0020] Examples of fluoroolefins include tetrafluoroethylene (hereinafter also referred to as "TFE"), vinyl fluoride, vinylidene fluoride, trifluoroethylene, hexafluoropropylene, and chlorotrifluoroethylene. Fluoroolefins may be used individually or in combination of two or more. Examples of fluoroolefin polymers include ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV). Fluoroolefin polymers may be used individually or in combination of two or more. Among fluoroolefin polymers, ETFE is particularly preferred due to its high elongation at high temperatures. ETFE is a copolymer having TFE units and ethylene units (hereinafter also referred to as "E units").

[0021] ETFE may have units based on a third monomer in addition to TFE units and E units. The third monomer may be used alone or in combination of two or more types. Examples of the third monomer include monomers having fluorine atoms and monomers not having fluorine atoms.

[0022] Examples of monomers containing a fluorine atom include the following monomers (a1) to (a5). Monomer (a1): Fluoroolefins having 2 or 3 carbon atoms. Monomer (a2): X(CF ２ ) ｎ CY = CH ２(However, X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer of 2 to 8.) Fluoroalkyl ethylenes represented by. Monomer (a3): Fluorovinyl ethers. Monomer (a4): Functional group-containing fluorovinyl ethers. Monomer (a5): Fluorine-containing monomers having an aliphatic ring structure.

[0023] As the monomer (a1), fluoroethylenes (trifluoroethylene, vinylidene fluoride, vinyl fluoride, chlorotrifluoroethylene, etc.), fluoropropylenes (hexafluoropropylene (hereinafter, also referred to as "HFP"), 2-hydroperfluoropropylene, etc.) and the like can be mentioned.

[0024] As the monomer (a2), monomers with n being 2 to 6 are preferable, and monomers with n being 2 to 4 are particularly preferable. Also, a monomer in which X is a fluorine atom and Y is a hydrogen atom, that is, (perfluoroalkyl) ethylene is particularly preferable. Specific examples of the monomer (a2) include the following compounds. CF ３ CF ２ CH=CH ２ 、 CF ３ CF ２ CF ２ CF ２ CH=CH ２ ((Perfluorobutyl) ethylene. Hereinafter, also referred to as "PFBE"), CF ３ CF ２ CF ２ CF ２ CF=CH ２ 、 CF ２ HCF ２ CF ２ CF=CH ２ 、 CF ２ HCF ２ CF ２ CF ２ CF=CH ２ etc.

[0025] Specific examples of the monomer (a3) include the following compounds. Among the following, monomers that are dienes are monomers that can undergo cyclopolymerization. CF ２ =CFOCF ３ 、 CF ２ =CFOCF２ CF ３ CF ２ = CFO (CF ２ ) ２ CF ３ (Perfluoro(propyl vinyl ether. Hereinafter also referred to as "PPVE"), CF ２ = CFOCF ２ CF (CF ３ )O(CF ２ ) ２ CF ３ CF ２ = CFO (CF ２ ) ３ O(CF) ２ ) ２ CF ３ CF ２ = CFO (CF ２ CF (CF ３ )O) ２ (CF ２ ) ２ CF ３ CF ２ = CFOCF ２ CF (CF ３ )O(CF ２ ) ２ CF ３ CF ２ = CFOCF ２ CF = CF ２ CF ２ = CFO (CF ２ ) ２ CF = CF ２ etc.

[0026] Specific examples of monomers (a4) include the following compounds: CF ２ = CFO (CF ２ ) ３ CO ２ CH ３ CF ２ = CFOCF ２ CF (CF ３ )O(CF ２ ) ３ CO ２ CH ３ CF ２ = CFOCF ２ CF (CF ３ )O(CF ２) ２ SO ２ F etc.

[0027] Specific examples of monomers (a5) include perfluoro(2,2-dimethyl-1,3-dioxol), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol, and perfluoro(2-methylene-4-methyl-1,3-dioxolane).

[0028] Examples of monomers that do not contain a fluorine atom include the following monomers (b1) to (b4): Monomer (b1): Olefins, Monomer (b2): Vinyl esters, Monomer (b3): ​​Vinyl ethers, Monomer (b4): Unsaturated acid anhydrides.

[0029] Specific examples of monomer (b1) include propylene and isobutene. Specific examples of monomer (b2) include vinyl acetate. Specific examples of monomer (b3) include ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, and hydroxybutyl vinyl ether. Specific examples of monomer (b4) include maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic acid anhydride.

[0030] As the third monomer, monomer (a2), HFP, PPVE, and vinyl acetate are preferred due to their ease of adjusting the degree of crystallinity and their excellent tensile strength and elongation at high temperatures (especially around 180°C). ３ CF ２ CH=CH ２ PFBE is more preferred, and PFBE is even more preferred.

[0031] In ETFE, the molar ratio of TFE units to E units (TFE units / E units) is preferably 80 / 20 to 40 / 60, more preferably 70 / 30 to 45 / 55, and particularly preferably 65 / 35 to 50 / 50. When the TFE units / E units are within the above range, ETFE exhibits excellent heat resistance and mechanical strength. The proportion of units based on the third monomer in ETFE is preferably 0.01 to 20 mol%, more preferably 0.10 to 15 mol%, and particularly preferably 0.20 to 10 mol%, relative to the total amount of all units constituting ETFE (100 mol%). When the proportion of units based on the third monomer is within the above range, ETFE exhibits excellent heat resistance and mechanical strength.

[0032] When the units based on the third monomer include PFBE units, the proportion of PFBE units is preferably 0.5 to 4.0 mol%, more preferably 0.7 to 3.6 mol%, and particularly preferably 1.0 to 3.6 mol%, relative to the total amount of all units constituting ETFE (100 mol%). When the proportion of PFBE units is within the above range, the tensile elongation at high temperatures (especially around 180°C) is improved.

[0033] The melting point of ETFE is preferably 190°C or higher, more preferably 200°C or higher, even more preferably 210°C or higher, and particularly preferably 220°C or higher. The upper limit of the melting point of ETFE is not particularly limited, but for example, it is 270°C. When the melting point of ETFE is within this range, the release film tends to have excellent tensile strength and elongation at high temperatures (especially around 180°C). "Melting point" refers to the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC).

[0034] The melt flow rate (MFR) of ETFE is preferably 2 to 40 g / 10 min, more preferably 3 to 30 g / 10 min, and particularly preferably 5 to 20 g / 10 min. When the ETFE MFR is within this range, the release film expands significantly at high temperatures, resulting in excellent conformability to the mold. The ETFE MFR is measured according to ASTM D3159 at a load of 49 N and 297°C. The fluororesin content in the total resin contained in the substrate is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, particularly preferably 99% by mass or more, and may also be 100% by mass.

[0035] The base material may further contain other components besides fluororesin. Examples of other components include resins other than fluororesin, lubricants, antioxidants, antistatic agents, plasticizers, and mold release agents. In terms of minimizing mold contamination, the content of other components in the base material is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0% by mass (not included).

[0036] The substrate may consist of a single layer containing fluororesin, or it may be a laminate containing a layer containing fluororesin and other layers.

[0037] When the substrate is a laminate, the other layers are preferably a shrinkable film layer or a reinforcing film layer. A shrinkable film is a resin film that shrinks in size when heated to room temperature (e.g., 25°C) or higher. This is preferable because, when this laminated film is used as a release film, it can suppress both the generation of wrinkles when the release film is brought into contact with the cavity surface during compression molding, and the generation of wrinkles when the bottom surface of the cavity to which the release film is attached is raised. A reinforcing film is a resin film with higher mechanical strength than fluororesin. This is preferable because, when this laminated film is used as a release film, it can suppress both the generation of wrinkles when the release film is brought into contact with the cavity surface during compression molding, and the generation of wrinkles when the bottom surface of the cavity to which the release film is attached is raised.

[0038] Examples of resins that make up the shrinkable film layer include polyvinyl chloride (PVC), polyester resins (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc.), polyolefin resins (polyethylene, polypropylene, etc.), polyamide resins (PA6, PA66, PA11, PA12, PAMDX6, etc.), polyphenylene sulfide (PPS), and bio-derived resins (resins mainly composed of polylactic acid, cellulose, chitin, chitosan, kenaf, etc.). The shrinkable film layer may consist of one or more resins. Among these, at least one selected from the group consisting of polyamide resins, polyester resins, polystyrene resins, and bio-derived resins is preferred in terms of excellent mechanical strength and film moldability.

[0039] Examples of resins that constitute the reinforcing film layer include polyvinyl chloride (PVC), polyester resins (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc.), polyolefin resins (polyethylene, polypropylene, etc.), polyamide resins (PA6, PA66, PA11, PA12, PAMDX6, etc.), polyphenylene sulfide (PPS), and bio-derived resins (resins mainly composed of polylactic acid, cellulose, chitin, chitosan, kenaf, etc.). The reinforcing film layer may consist of one or more resins. Among these, at least one selected from the group consisting of polyamide resins, polyester resins, polystyrene resins, and bio-derived resins is preferred in terms of excellent mechanical strength and film moldability.

[0040] The shrinkable film and the reinforcing film may further contain additives as needed. Examples of additives include colorants, antioxidants, thermal degradation inhibitors, and stabilizers.

[0041] When the substrate is a laminate, it is preferable that the other side of the substrate (hereinafter also referred to as the "second substrate side") be a fluororesin layer, from the viewpoint of high thermal stability and suppressing film decomposition, migration of low molecular weight components to the surface, and consequently contamination of mold surfaces, etc., that come into contact with the film, depending on the heating conditions during use. Furthermore, when the substrate is a laminate, a combination of one shrinkable film layer or reinforcing film layer and one to two fluororesin layers is preferable. When the substrate is a laminate, the configuration of the laminated film is preferably a functional layer / shrinkable film layer or reinforcing film layer / fluororesin layer, or a functional layer / fluororesin layer / shrinkable film layer or reinforcing film layer / fluororesin layer.

[0042] When the substrate is a laminate, it is preferable that each layer is laminated via an adhesive layer. Examples of adhesive layers include layers formed from adhesives. The adhesive may be an adhesive known for dry lamination, for example. Examples of adhesives include polyvinyl acetate adhesives, polyacrylic acid ester adhesives consisting of homopolymers or copolymers of acrylic acid esters (ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), or copolymers of acrylic acid esters with other monomers (methyl methacrylate, acrylonitrile, styrene, etc.), cyanoacrylate adhesives, ethylene copolymer adhesives consisting of copolymers of ethylene with other monomers (vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc.), cellulose adhesives, polyester adhesives, and polyamide adhesives. Examples of adhesives include: polyimide adhesives, amino resin adhesives made of urea resin or melamine resin, phenol resin adhesives, epoxy adhesives, polyurethane adhesives made of combinations of polyols (polyether polyols, polyester polyols, etc.) and polyisocyanates or their reaction products (isocyanate group-containing polyurethane prepolymers, etc.), reactive (meth)acrylic adhesives, rubber adhesives made of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc., silicone adhesives, and inorganic adhesives made of alkali metal silicates, low-melting-point glass, etc. The dry coating amount of the adhesive is 0.1 to 5 g / m². ２It may be. The thickness (μm) of the adhesive layer can be converted from the above dry coating amount (g / m ２ ), using the density of the adhesive material.

[0043] In this laminated film, the Ra of the second surface of the base material is 0.3 to 1.9 μm. The second surface of the base material is the surface opposite to the surface (the first surface of the base material) on which the functional layer is provided, and is the surface that contacts the functional layer in the state where the laminated film is wound up. When the Ra of the second surface of the base material is 0.3 μm or more, blocking is unlikely to occur on the contact surface between the laminated films, which is preferable. Also, when the Ra is 1.9 μm or less, a laminated film in which the film surface on the side where the concavo-convex shape is imparted is unlikely to change can be obtained, which is preferable. From the viewpoint of the slipperiness on the mold surface when applied to mold molding, the Ra is more preferably 0.5 μm or more, and for the same reason, it is more preferably 1.8 μm or less. The Ra may be 0.5 to 1.8 μm. To make the Ra of the second surface of the base material within the above range, for example, as described later, a method of transferring the concavo-convex of the master mold to the surface can be mentioned.

[0044] In this laminated film, the thickness of the base material is preferably 6 to 500 μm, more preferably 25 to 300 μm, still more preferably 35 to 100 μm, and particularly preferably 35 to 75 μm, whether it is a single layer or a laminate. If the thickness of the base material is 6 μm or more, the laminated film of the present disclosure is likely to have excellent releasability. If the thickness of the base material is 500 μm or less, the handling (for example, roll-to-roll handling) when using this laminated film as a release film is easy, and wrinkles are unlikely to occur when arranging it to cover the cavity of the mold while pulling the release film.

[0045] When the base material is a laminate, from the viewpoint of excellent film-forming properties, the fluororesin layer is preferably 3 to 300 μm, and other layers such as the shrinkable film layer are preferably 3 to 300 μm. Also, the ratio of the total thickness of the fluororesin layer to the total thickness of the other layers is preferably 1:9 to 9:1.

[0046] The thickness of the base material is determined by observing the cross section of the laminated film using an optical microscope, measuring the thickness of the layer corresponding to the base material at 5 locations, and calculating the average value.

[0047] From the viewpoint of conformability to the mold at 175°C, the tensile elongation of the substrate is preferably 100% or more, and more preferably 150% or more at 175°C. Furthermore, since morphological stability of the film is required after conformability to the mold, there may be a practical upper limit to the elongation, preferably 2,000% or less, and more preferably 1,000% or less. The tensile elongation of the substrate can be measured according to JIS K7127:1999.

[0048] The storage modulus of the substrate at 175°C (hereinafter also referred to as "storage modulus (175°C)") is preferably 0.5 MPa or higher, more preferably 5 MPa or higher, even more preferably 20 MPa or higher, and particularly preferably 35 MPa or higher. It is also preferably 100 MPa or lower, more preferably 75 MPa or lower, and particularly preferably 60 MPa or lower. 175°C is a typical mold temperature when sealing semiconductor elements. If the storage modulus (175°C) is below the upper limit of the above range, the release film will exhibit appropriate elongation under high-temperature conditions, the release film will adhere securely to the cavity surface, and a highly accurate resin seal will be formed. If the storage modulus (175°C) is above the lower limit of the above range, the release film will exhibit appropriate strength under high-temperature conditions, and tearing and pinholes are less likely to occur when the release film is positioned to cover the cavity surface of the mold while being pulled under vacuum. Furthermore, the tension is applied uniformly to the release film, making it less likely to wrinkle, and reducing the likelihood of appearance defects caused by wrinkles in the release film being transferred to the surface of the resin-sealed area.

[0049] The storage modulus (175°C) is measured according to ISO 6721-4:1994 (JIS K7244-4:1999). The frequency is 10 Hz, the static force is 0.98 N, and the dynamic displacement is 0.035%. The temperature is increased from 20°C at a rate of 2°C / min, and the modulus measured at 175°C is defined as the storage modulus (175°C). The storage modulus of the substrate of this laminated film can be measured by peeling off the functional layer from the laminated film, leaving only the substrate.

[0050] (Functional layer) The functional layer is preferably a layer that has the necessary functions when the laminated film is used as a release film. Examples of such functions include tackiness, release properties, antistatic properties, and shape-imparting properties, and it is preferable that the functional layer has at least one of these functions.

[0051] It is preferable for the functional layer to be adhesive, from the viewpoint of easily exhibiting the effects of the present invention. This is because if the functional layer is adhesive, blocking is likely to occur at the contact surface between the laminated films. In this case, it is preferable that the outermost surface of the functional layer contains at least one resin selected from acrylic resin, urethane resin, polyester resin, and epoxy resin. Having these resins on the outermost surface makes blocking more likely to occur at the contact surface between the laminated films, which is preferable as it makes it easier to exhibit the effects of the present invention. For the outermost surface of the functional layer to contain the above resin, if the functional layer consists of a single layer, it is sufficient that the single layer contains the above resin, and if the functional layer is a laminate of multiple layers, it is sufficient that the outermost layer contains the above resin.

[0052] The functional layer may comprise multiple layers necessary to exhibit various functions such as tackiness, release properties, antistatic properties, and shape-forming properties, or it may comprise layers corresponding to each function. If the functional layer has a single-layer structure, for example, the functional layer may be a release layer, or it may be an adhesive release layer. If the functional layer is a laminate of two or more layers, the functional layer may comprise a release layer and an antistatic layer, or it may comprise an adhesive release layer and an antistatic layer.

[0053] From the viewpoint of using the laminated film as a release film, the functional layer preferably has a release layer. The material of the release layer is not limited as long as it is a layer with release properties, but the release layer is usually provided on the outermost surface of the functional layer. If the functional layer is adhesive, the laminated films tend to adhere to each other, so blocking is likely to occur at the contact surface of the films. Therefore, it is preferable for the release layer to be adhesive from the viewpoint of easily exhibiting the effects of the present invention. In this case, from the viewpoint of the release layer being adhesive, it is preferable that it contains at least one resin selected from acrylic resin, urethane resin, polyester resin, and epoxy resin.

[0054] In particular, the release layer is more preferably made of an acrylic resin, and from the viewpoint of release properties for encapsulating resins (e.g., epoxy compounds) used in semiconductor encapsulation and heat resistance to withstand use in transfer molding processes where the mold and encapsulating resin are at high temperatures, it is especially preferable that the release layer contains a reaction-cured product of a hydroxyl group-containing acrylic polymer and a bifunctional or more isocyanate compound (hereinafter also referred to as a "polyfunctional isocyanate compound"). In this case, the hydroxyl group-containing (meth)acrylic polymer reacts with the polyfunctional isocyanate compound to crosslink and become a reaction-cured product. The release layer may also be a reaction-cured product of a hydroxyl group-containing (meth)acrylic polymer, a polyfunctional isocyanate compound, and other components.

[0055] The release layer may further contain other components such as release agents, antistatic agents, lubricants, colorants, and coupling agents.

[0056] Examples of release agents include silicone compounds and fluorine compounds.

[0057] Examples of antistatic agents include ionic liquids, conductive polymers, metal ion-conducting salts, and conductive fillers. Examples of ionic liquids include pyridinium, imidazolium, and other onium and fluorine compounds. Conductive polymers are polymers in which electrons move and diffuse along the polymer skeleton. Examples of conductive polymers include polyaniline polymers, polyacetylene polymers, poly-p-phenylene polymers, polypyrrole polymers, polythiophene polymers, and polyvinylcarbazole polymers. Examples of conductive fillers include metal ion-conducting salts, metals, metal oxides, metal coatings, metal oxide coatings, conductive carbon, and conductive carbon nanotubes. Examples of metal ion-conducting salts include lithium salt compounds. Examples of metal oxides in metal oxide fillers and metal oxide-coated fillers include tin oxide, tin-doped indium oxide, antimond-doped tin oxide, phosphorus-doped tin oxide, zinc antimonate, and antimony oxide.

[0058] Examples of lubricants include microbeads made of thermoplastic resin, fumed silica, and polytetrafluoroethylene (PTFE) fine particles. Examples of colorants include various organic and inorganic colorants, more specifically, cobalt blue, red iron oxide, and cyanine blue. Examples of coupling agents include silane coupling agents and titanate coupling agents.

[0059] It is even more preferable that the functional layer has two layers: a release layer and an antistatic layer. Having an antistatic layer is preferable because it can suppress the generation of static electricity when peeling the release film from the resin encapsulation part. When the functional layer has a release layer and an antistatic layer, it is preferable that the laminated film has the layers in the order of substrate, antistatic layer, and release layer.

[0060] The antistatic layer is not limited in material as long as it has an antistatic function, but it is preferable that it contains an antistatic agent. An example of an antistatic agent is the antistatic agent contained in the release layer mentioned above. The amount of antistatic agent in the antistatic layer is set appropriately so that the surface resistance value is within the desired range.

[0061] The antistatic layer also preferably contains a resin binder to improve the dispersibility of the antistatic agent. Examples of resin binders include those contained in the functional layer. The resin binder is preferably heat-resistant, capable of withstanding the heat (e.g., 180°C) during the sealing process, and a thermosetting resin is preferred. Examples of thermosetting resins include acrylic resins, silicone resins, and urethane resins, with acrylic resins obtained by crosslinking a carboxyl group-containing acrylic polymer with a polyfunctional aziridine compound or a polyfunctional epoxy compound, and acrylic resins obtained by crosslinking a hydroxyl group-containing acrylic polymer with a polyfunctional isocyanate compound. Examples of other resin binders include polyester resins, polyamide resins, vinyl acetate resins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, chlorotrifluoroethylene-vinyl alcohol copolymers, and tetrafluoroethylene-vinyl alcohol copolymers.

[0062] From the viewpoint of excellent heat resistance and dispersibility of antistatic agents, polyester resin or acrylic resin is preferred as the resin binder. The resin binder may be crosslinked. When the resin binder is crosslinked, it has superior strength and heat resistance compared to when it is not crosslinked.

[0063] The antistatic layer may also contain release agents, lubricants, colorants, and coupling agents, which may be included in the release layer.

[0064] The thickness of the functional layer is preferably 0.01 to 10 μm, and more preferably 0.05 to 5 μm, from the viewpoint of allowing the various functions of the functional layer to be fully exhibited and of mold release properties. The thickness of the functional layer can be measured by cross-sectional observation using an optical microscope. Furthermore, the dry coating amount of the functional layer is preferably 0.01 to 20 g / m², from the viewpoint of allowing the various functions of the functional layer to be fully exhibited and of mold release properties. ２ Preferably, 0.01 to 10 g / m ２ More preferably, 0.05 to 10 g / m ２ This is particularly preferable. The dry coating amount of the functional layer can be calculated by removing the layer to be measured using a solvent and taking the change in mass before and after removal. Details will be explained in the examples. Note that the thickness of the functional layer (μm) and the dry coating amount (g / m) are as follows. ２ These can be converted to each other using the density of the material in the functional layer.

[0065] When the functional layer is a multilayer having an antistatic layer and a release layer, the thickness of the antistatic layer is 0.01 to 10 g / m² as the dry coating amount of the antistatic layer composition. ２ It may be as follows. The thickness of the release layer may be 0.01 to 50 g / m² as the dry coating amount of the release layer composition. ２ That's fine.

[0066] The surface of the functional layer (the surface opposite to the substrate side) may have a minute uneven surface. The surface of the functional layer is the surface that comes into contact with the curable resin when the laminated film is used as a release film. Therefore, it is preferable that this surface has a minute uneven surface, as this makes it possible to form a semiconductor package surface with excellent laser marking visibility. Specifically, the Ra of the functional layer surface is preferably 0.1 μm or more, and more preferably 0.3 μm or more.

[0067] (Physical Properties of the Multilayer Film) For this multilayer film, the Ra of the surface on the functional layer side is preferably 0.01 μm or more, more preferably 0.03 μm or more. When it is desired to form a semiconductor package surface with excellent laser marking visibility, the Ra of the surface on the functional layer side is preferably 0.1 μm or more, more preferably 0.3 μm or more. For this multilayer film, the Ra of the surface on the base material side is preferably 0.3 to 1.9 μm. More preferably, it is 0.5 μm or more, and more preferably 1.8 μm or less. Ra may be 0.5 to 1.8 μm.

[0068] The surface resistivity of the surface on the functional layer side of this multilayer film is preferably 1 × 10 １０ Ω / sq or less, more preferably 5 × 10 ９ Ω / sq or less, and even more preferably 3 × 10 ９ Ω / sq or less. If the surface resistivity is 1 × 10 １０ Ω / sq or less, destruction of the semiconductor chip due to discharge during peeling can be effectively prevented. The lower limit value of the surface resistivity of the surface on the functional layer side is not particularly limited, but it may also be 1 × 10 ７ Ω / sq or more. In order to make the surface resistivity within the above range, for example, adjusting the content of the antistatic agent in the functional layer can be mentioned. The surface resistivity can be measured in accordance with IEC 60093, the double ring electrode method.

[0069] The tensile elongation of this multilayer film at 175°C is preferably 100 to 1000%, more preferably 200 to 800%, and even more preferably 350 to 500%. When the tensile elongation is within such a range, when this multilayer film is used as a release film, it is preferable because it is likely to have excellent shape followability to the mold. Also, when the tensile elongation is not less than the above lower limit value, it is preferable because film breakage is less likely to occur during mold following.

[0070] <Method for Manufacturing Laminated Film> As for the substrate, one side on which the functional layer is provided (hereinafter also referred to as the "first substrate surface") may be either a mirror surface or an uneven surface. On the other hand, the second substrate surface has an Ra of 0.3 to 1.9 μm. As for the method for manufacturing such a substrate, known manufacturing methods can be used. For example, one method is to transfer the unevenness of the original mold to the second substrate surface of the resin film by heat processing, and from the viewpoint of productivity, for example, the following methods (i) or (ii) can be used.

[0071] (i) A method of passing a resin film between two rolls and continuously transferring the irregularities formed on the surface of the rolls to the surface (second surface) on which the irregularities of the resin film are formed. (ii) A method of passing resin extruded from the die of an extruder between two rolls to form the resin into a film, and continuously transferring the irregularities formed on the surface of the rolls to the surface (second surface) on which the irregularities of the film-like resin are formed.

[0072] The roll surface in contact with the first surface of the substrate may be a mirror surface or have an uneven shape.

[0073] Furthermore, in order to change Ra within a specific range, methods include changing the uneven shape of the original mold according to the desired Ra, changing the thickness of the resin film or resin passed through the two rolls, changing the temperature of the resin film, changing the film formation speed when the film is formed by continuously extruding and the surface shape is formed by passing it through the two rolls, and changing the force applied from the rolls to the resin film or resin.

[0074] Furthermore, if the substrate is a laminate comprising a layer containing fluororesin and other layers, for example, a resin film can be manufactured by laminating the layer containing fluororesin and other layers using dry lamination with an adhesive, and the original mold's irregularities can be transferred to the second surface of the substrate using method (i) above.

[0075] The functional layer is formed, for example, by a coating method in which a functional layer composition described later is applied to the first surface of a substrate. When the functional layer is a single layer, a method of applying the functional layer composition to the first surface of the substrate and drying is preferred. Various known wet coating methods can be used for the coating method, such as gravure coating, die coating, and bar coating. The drying temperature and time are adjusted as appropriate depending on the type and content of the liquid medium.

[0076] When the functional layer is a multilayer including an antistatic layer and a release layer, it is preferable to apply an antistatic layer composition containing an antistatic agent, etc., to the first surface of the substrate, dry it to form the antistatic layer, and then apply a release layer composition on top of the antistatic layer and dry it to form the release layer. Various known wet coating methods can be used for the coating method, such as the gravure coating method, die coating method, and bar coating method. The drying temperature and time are adjusted as appropriate depending on the type and content of the liquid medium. The antistatic layer composition and the release layer composition may each contain the components that make up each layer, and optionally a curing agent, a solvent, water, or other liquid medium.

[0077] Before applying the functional layer composition or the antistatic layer composition, it is preferable to corona treat the first surface of the substrate to improve wettability. The corona treatment is preferably carried out so that the wettability tension, according to ISO 8296:1987 (JIS K6768:1999), is 40 mN / m or more.

[0078] The drying temperature and time for the functional layer should be adjusted as appropriate depending on the type and content of the liquid medium.

[0079] <Method for Manufacturing Semiconductor Packages> This laminated film is useful as a release film used in the sealing process when manufacturing a semiconductor package having a semiconductor element and a resin sealing portion formed from a curable resin that seals the semiconductor element. A method for manufacturing a semiconductor package using this laminated film includes, for example, placing a substrate equipped with a semiconductor element in the cavity of a mold, placing a release film made of this laminated film on the cavity surface of the mold where the substrate is not placed, with the functional layer side of the laminated film facing the space inside the cavity of the mold, filling the cavity with a curable resin, and curing the curable resin in contact with the release film to form a resin sealing portion that seals the semiconductor element. Examples of curable resins include epoxy resins. The curable resin may also be used as a composition containing a curing agent. The curing agent may be an amine-based curing agent.

[0080] The semiconductor package manufacturing method of this disclosure can employ known manufacturing methods, except for the use of the laminated film as a release film. For example, compression molding or transfer molding can be used as methods for forming the resin encapsulation portion, and known compression molding apparatus or transfer molding apparatus can be used as the equipment in this process. The manufacturing conditions are also the same as those in known semiconductor package manufacturing methods.

[0081] The present invention will be described in more detail below using examples, but the present invention is not limited to these. Examples 1-1 to 1-4 are examples. Examples 1-5 to 1-6 are comparative examples. Examples 2-1 to 2-9 are examples. Examples 2-10 to 2-13 are reference examples.

[0082] [Examples 1-1 to 1-6] <Materials Used> (Base Material) ETFE (Fluon® ETFE C-88AXP (manufactured by AGC Corporation))

[0083] (Composition for antistatic layer) An antistatic layer composition (solids content 2% by mass) was prepared by mixing an antistatic agent-containing material (100 parts by mass), a curing agent (10 parts by mass), and methanol (100 parts by mass). Antistatic agent-containing material: Aracoat® AS601D (manufactured by Arakawa Chemical Industries, Ltd.), solids content 3.4%, conductive polythiophene 0.4%, acrylic resin 3.0%. Curing agent: Aracoat® CL910 (manufactured by Arakawa Chemical Industries, Ltd.), solids content 10%, polyfunctional aziridine compound.

[0084] (Composition for mold release layer) A mold release layer composition (solid content 25% by mass) was prepared by mixing an acrylic polymer (100 parts by mass), a polyfunctional isocyanate compound (4 parts by mass), and ethyl acetate. Acrylic polymer: Nissetsu (registered trademark) KP2562 (manufactured by Nippon Carbide Industries Co., Ltd.). Polyfunctional isocyanate compound: Nissetsu CK157 (manufactured by Nippon Carbide Industries Co., Ltd.), solid content 100%, isocyanurate-type hexamentiene diisocyanate, NCO content 21% by mass.

[0085] <Example 1-1> ETFE was fed into an extruder equipped with a T-die and taken up between a rubber-wound roll having an uneven surface and a metal roll having a mirror surface to produce a substrate film having an uneven surface (substrate second surface) and a mirror surface (substrate first surface), with the thickness and surface roughness shown in Table 1. The temperature of the extruder and T-die was 320°C, and the temperature of the rubber-wound roll and metal roll was 100°C. The surface of the substrate first surface was subjected to corona treatment so that the wetting tension according to ISO 8296:1987 (JIS K6768:1999) was 40 mN / m or more. An antistatic layer composition was applied to the surface of the substrate first surface using a gravure coater and dried to form an antistatic layer. Coating was performed using a reverse gravure method, and drying was performed at 100°C for 1 minute. Next, a release layer composition was applied to the surface of the antistatic layer using a gravure coater and dried to form a release layer. The coating was performed using a reverse gravure method, and drying was carried out at 100°C for 1 minute. Subsequently, the film was cured at 40°C for 120 hours to obtain a laminated film. The first surface of the substrate is the surface on which the functional layer is provided. The second surface of the substrate is the surface on the opposite side of the substrate from the surface on which the functional layer is provided.

[0086] <Examples 1-2 to 1-6> Laminated films were obtained in the same manner as in Example 1-1, except that the thickness of the substrate and the Ra of the second surface of the substrate were changed as shown in Table 1.

[0087] [Examples 2-1 to 2-13] <Materials used> (Base material) ETFE: Fluon (registered trademark) ETFE C-88AXP (manufactured by AGC Inc.) PET: Toyobo Co., Ltd. G2CU0 Urethane adhesive: The main component and the hardener were mixed so that the mass ratio of solids (main component:hardener) was 10:1, and the urethane adhesive was prepared by diluting with ethyl acetate. Main component: Crisbon (registered trademark) NT-258 (manufactured by DIC Corporation). Hardener: Coronate 2096 (manufactured by Nippon Polyurethane Industry Co., Ltd.).

[0088] (Composition for antistatic layer) Same as in Example 1-1.

[0089] (Composition for release layer) Same as in Example 1-1.

[0090] <Example 2-1> A urethane adhesive was applied to one side of PET using a gravure roll and dried at 60°C. ETFE was then layered onto this coated surface and roll-pressed at 60°C and 1 m / min to obtain a PET / ETFE laminate. A urethane adhesive was applied to the PET side of this laminate and dried at 60°C. ETFE was then layered onto this coated surface and roll-pressed at 60°C and 1 m / min to obtain an ETFE / PET / ETFE laminate. The ETFE / PET / ETFE laminate was fed into an extruder equipped with a T-die and pulled between a rubber-wrapped roll with an uneven surface and a metal roll with a mirrored surface to produce a substrate with an uneven surface (second substrate surface) and a mirrored surface (first substrate surface), with the thickness and Ra shown in Table 2. The temperature of the extruder and T-die was 320°C, and the temperature of the rubber-wrapped roll and metal roll was 100°C. The surface of the first surface of the substrate was subjected to corona treatment so that the wet tensile strength, according to ISO 8296:1987 (JIS K6768:1999), was 40 mN / m or more. An antistatic layer was formed on the surface of the first surface of the substrate in the same manner as in Example 1-1, and then a release layer was formed on the surface of the antistatic layer in the same manner as in Example 1-1. The film was then cured at 40°C for 120 hours to obtain a laminated film.

[0091] <Examples 2-2 to 2-13> Laminated films were obtained in the same manner as in Example 2-1, except that the type of substrate, the thickness of the ETFE, and the Ra of the second surface of the substrate were changed as shown in Table 2 or Table 3.

[0092] [Evaluation Method] (Thickness of base material and laminated film) The thickness (μm) of the base material and laminated film was determined by measuring the cross-section at five points using an optical microscope and calculating the average value.

[0093] (Coating amount of antistatic layer and release layer) A 12 cm x 12 cm piece was cut from the laminated film, and the layer to be measured was removed by rubbing it with a 500 g load using a Kimwipe impregnated with a solvent. The coating amount (solid content) was calculated from the change in mass before and after removal. The layer removal was performed by using both isopropyl alcohol and ethyl acetate as solvents separately and sequentially. Layer removal and mass measurement were continued until the measured mass no longer changed. The load was measured by placing a glass plate on a balance and rubbing on it.

[0094] (Arithmetic mean roughness (surface roughness) Ra) Ra (μm) was measured according to JIS B0601:2013 (ISO 4287:1997, Amd. 1:2009). The reference length lr (cutoff value λc) was 0.8 mm, and the measurement length was 8 mm. For the measurement, a surface roughness measuring instrument (SURFCOM 480A, manufactured by Tokyo Seimitsu Co., Ltd.) was used, and Ra was determined at a total of 6 locations: 3 locations perpendicular to the flow direction during film manufacturing and 3 locations parallel to it. The average value of these values ​​was taken as the Ra of the surface in question.

[0095] (Presence or absence of electrostatic discharge breakdown) A transfer mold test was conducted using an Apic Yamada Co., Ltd. molding device and an Apic Yamada Co., Ltd. transfer mold. Sumitomo Bakelite Co., Ltd. EGE 770GH was used as the sealing material. The molding temperature was 175°C. Molding was performed using a 73 mm wide, 230 mm long, and 200 μm thick Tip copper substrate. The mold depth was set to 0.4 mm so that a 200 μm thick EMC-cured material could be molded onto the copper plate. During molding, the device was stopped 30 seconds after the mold opened, and the electrostatic charge potential was measured using a charge meter (Keyence Corporation, electrostatic charge meter SK-H050) and evaluated according to the following criteria. A: Electrostatic charge potential less than 10 kV (no electrostatic discharge breakdown occurred, pass) B: Electrostatic charge potential 10 kV or more (electrostatic discharge breakdown occurred, fail)

[0096] (Roll Winding Test (Presence or Absence of Air Bubbles)) Laminated film was manufactured and wound into a roll using a 15 cm diameter core with a constant tension of 150 N per width. The resulting master roll was visually inspected from the horizontal and evaluated according to the following criteria: A: No air bubbles are trapped between the laminated films, resulting in a uniform winding state (Pass) B: Air bubbles are trapped between the laminated films (Fail)

[0097] (Presence or absence of surface morphological abnormalities in molded products) A transfer mold test was conducted using an Apic Yamada Co., Ltd. molding device and an Apic Yamada Co., Ltd. transfer mold. Sumitomo Bakelite Co., Ltd. EGE 770GH was used as the sealing material. The molding temperature was 175°C. Molding was performed using a 73 mm wide, 230 mm long, and 200 μm thick Tip copper substrate. The depth of the mold was set to 0.4 mm so that a 200 μm thick EMC cured product could be molded onto the copper plate. Visual inspection of the sealing resin surface of the obtained molded products revealed that the surface texture of the film used had been transferred. The products were evaluated according to the following criteria: A: The appearance is uniform (no morphological abnormalities, pass) B: Irregularities on the surface of the laminated film are unevenly transferred (morphological abnormalities present, fail)

[0098] (Slit Roll Storage Test) The laminated film obtained in the roll winding test was wound up to a width of 190 mm and a length of 260 m using a core with a diameter of 8 cm. The winding tension at this time was set to 100 N / m. The obtained slit roll was stored at 40°C for 5 days and then cooled to 25°C. The Ra of the second surface of the substrate was measured before and after storage at 40°C for 5 days and evaluated according to the following criteria. A: Ra did not change before and after storage (pass) B: Ra changed before and after storage (fail)

[0099] The results are shown in Tables 1-4.

[0100]

[0101]

[0102]

[0103] In Examples 1-1 to 1-4, the laminated films with a Ra of the second surface of the substrate in the range of 0.3 to 1.9 μm did not generate bubbles in the roll winding test, showed no change in Ra before and after storage in the slit roll storage test, and did not exhibit any surface morphological abnormalities in the molded products. In Example 1-5, the laminated film with an Ra of less than 0.3 μm on the second surface of the substrate generated bubbles in the roll winding test and exhibited surface morphological abnormalities in the molded products. In Example 1-6, the laminated film with an Ra of greater than 1.9 μm on the second surface of the substrate showed a change in Ra before and after storage in the slit roll storage test. In addition, since the functional layer of the laminated films in Examples 1-1 to 1-6 has an antistatic layer, no electrostatic discharge breakdown occurred.

[0104] Laminated films of Examples 2-1 to 2-9, in which the Ra of the second surface of the substrate was in the range of 0.3 to 1.9 μm, did not generate bubbles in the roll winding test, showed no change in Ra before and after storage in the slit roll storage test, and did not exhibit surface morphological abnormalities in the molded products. Laminated films of Examples 2-10 and 2-12, in which the Ra of the second surface of the substrate was less than 0.3 μm, generated bubbles in the roll winding test and exhibited surface morphological abnormalities in the molded products. Laminated films of Examples 2-11 and 2-13, in which the Ra of the second surface of the substrate was greater than 1.9 μm, showed a change in Ra before and after storage in the slit roll storage test. In addition, since the functional layer of the laminated films of Examples 2-1 to 2-13 has an antistatic layer, no electrostatic discharge breakdown occurred.

[0105] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-173376 filed on 2 October 2024, the contents of which are incorporated herein by reference.

[0106] The laminated film disclosed in this invention is useful as a release film that is less prone to blocking at the contact surfaces between films and less prone to changes in the film surface. Semiconductor packages can be manufactured using the laminated film disclosed herein.

[0107] 10 Laminated Film 1 Substrate 1A Substrate 1st surface (one side of the substrate) 1B Substrate 2nd surface (the other side of the substrate) 2 Functional layer 3 Antistatic layer 4 Release layer

Claims

1. A laminated film comprising a base material and a functional layer provided on one side of the base material, wherein the base material contains a fluororesin and the arithmetic mean roughness Ra of the other side of the base material is 0.3 to 1.9 μm.

2. The laminated film according to claim 1, wherein the substrate comprises a fluoroolefin polymer.

3. The laminated film according to claim 1, wherein the outermost surface of the functional layer contains at least one resin selected from acrylic resin, urethane resin, polyester resin, and epoxy resin.

4. The laminated film according to claim 1, wherein the functional layer has a release layer.

5. The laminated film according to claim 1, wherein the functional layer has an antistatic layer.

6. The laminated film according to claim 1, wherein the functional layer comprises an antistatic layer and a release layer.

7. The dry coating amount of the functional layer is 0.01 to 20 g / m². ２ The laminated film according to claim 1.

8. A laminated film according to any one of claims 1 to 7, used as a release film.

9. A laminated film according to any one of claims 1 to 7, used in the manufacture of a semiconductor package.

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