Manufacturing method for single-sided metal-clad laminates

Abstract

The present invention relates to a method for manufacturing a single-side metal-clad layered plate comprising: core layers (110, 120) made of a heat-resistant film; and metal foil (151, 152) adhesively layered onto thermoplastic resin layers (111, 121) on one side of an adhesive sheet comprising thermoplastic resin layers (111, 112, 121, 122) provided on both sides of the core layers. A first metal foil (151), a first adhesive sheet (101), a second adhesive sheet (102), and a second metal foil (152) are thermally laminated to form a layered body, and by peeling the layered body apart between the first adhesive sheet and the second adhesive sheet, a first single-sided metal-clad layered plate (121) of the first adhesive sheet which has the first metal foil adhesively layered on a first main surface thereof, and a second single-sided metal-clad layered plate (122) of the second adhesive sheet which has the second metal foil adhesively layered on a first main surface thereof are obtained at the same time.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a single-sided metal-clad laminate.

Background Art

[0002] A flexible printed wiring board (FPC) having a metal wiring formed by patterning a metal layer such as copper on a heat-resistant resin film such as a polyimide film is used in various electronic devices. With the high performance and miniaturization of electronic devices, the development of a multilayer FPC in which a plurality of wiring layers are laminated with an insulating layer interposed therebetween has been progressing.

[0003] In the manufacture of FPCs, double-sided metal-clad laminates in which metal foils such as copper are laminated on both sides of a heat-resistant resin film and single-sided metal-clad laminates in which a metal foil is laminated on one side of a heat-resistant resin film are used. In the manufacture of multilayer FPCs, mainly single-sided metal-clad laminates are used.

[0004] As a method for manufacturing a metal-clad laminate, a method is known in which a multilayer film having a thermoplastic resin layer functioning as an adhesive layer on both sides of a heat-resistant resin film (core layer) is used, and a metal foil is thermally laminated to the thermoplastic resin layer of the multilayer film. A single-sided metal-clad laminate can be obtained by laminating a metal foil only on one side of a multilayer film having thermoplastic resin layers on both sides of the core layer. When laminating a metal foil only on one side of a multilayer film having thermoplastic resin layers on both sides of the core layer, problems such as the thermoplastic resin layer on the side where the metal foil is not laminated fusing to a heat roll or the like may occur during thermal lamination.

[0005] In Patent Document 1, a method has been proposed in which, in a method for manufacturing a single-sided metal-clad laminate in which a metal foil is laminated on one side of a multilayer film, thermal lamination is performed with a metal foil disposed on one surface of the multilayer film and a release film disposed on the other surface. In Patent Document 2, a method has been proposed in which a non-fusing or low-fusing surface layer is provided on the thermoplastic resin layer on one surface of a multilayer film, and a metal foil is disposed on the thermoplastic resin layer on the other surface of the multilayer film and thermal lamination is performed.

[0006] As proposed in Patent Documents 1 and 2, by performing thermal lamination with a release film or surface layer placed on the thermoplastic resin layer on the side where the metal foil is not laminated, it is possible to prevent the thermoplastic resin layer from fusing to manufacturing equipment such as metal rolls. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2007-109694 [Patent Document 2] International Publication No. 2021 / 251214 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to provide a single-sided metal-clad laminate with higher productivity while preventing the thermoplastic resin layer from fusing to manufacturing equipment such as metal rolls, by using a multilayer film having thermoplastic resin layers on both sides of a heat-resistant resin film (core layer). [Means for solving the problem]

[0009] The present invention relates to a method for manufacturing a single-sided metal-clad laminate comprising an adhesive sheet having thermoplastic resin layers on both sides of a core layer made of a heat-resistant film, and a metal foil closely laminated to the thermoplastic resin layer on one side of the adhesive sheet.

[0010] The first metal foil, first adhesive sheet, second adhesive sheet, and second metal foil are arranged so that the first main surface of the first adhesive sheet faces the first main surface of the first metal foil, the second main surface of the first adhesive sheet faces the second main surface of the second adhesive sheet, and the first main surface of the second adhesive sheet faces the first main surface of the second metal foil, and then heat lamination is performed. This forms a laminate in which the first metal foil, first adhesive sheet, second adhesive sheet, and second metal foil are laminated (lamination process). By peeling and separating this laminate between the first adhesive sheet and the second adhesive sheet (peeling process), a first single-sided metal-clad laminate in which the first metal foil is tightly laminated on the first main surface of the first adhesive sheet and a second single-sided metal-clad laminate in which the second metal foil is tightly laminated on the first main surface of the second adhesive sheet are obtained simultaneously.

[0011] The first adhesive sheet and the second adhesive sheet each have a thermoplastic resin layer on both sides of a core layer made of a heat-resistant film. The core layer of the adhesive sheet may be a non-thermoplastic polyimide film. The thermoplastic resin layer of the adhesive sheet may contain a thermoplastic polyimide resin. The tensile modulus of the adhesive sheet at a temperature of 350°C may be 0.05 to 1.5 GPa.

[0012] In the lamination process, thermal lamination may be performed by bringing the metal foils into contact with a heat-compression bonding means without placing any other layers on the second main surface of the first metal foil and the second main surface of the second metal foil. Alternatively, a surface protection film may be placed on the second main surface of the first metal foil and / or the second main surface of the second metal foil, and thermal lamination may be performed with the surface of the metal foils protected by the surface protection film. When a surface protection film is used, in the peeling process, peeling is performed not only between the first adhesive sheet and the second adhesive sheet, but also at the interface between the metal foil and the surface protection film.

[0013] In the lamination process, lamination may be carried out without placing any other layer between the first adhesive sheet and the second adhesive sheet, such that the thermoplastic resin layer on the second main surface of the first adhesive sheet (second thermoplastic resin layer) and the thermoplastic resin layer on the second main surface of the second adhesive sheet (second thermoplastic resin layer) are in contact. Alternatively, lamination may be carried out with an intermediate protective film placed between the first adhesive sheet and the second adhesive sheet.

[0014] If no other layer is placed between the first adhesive sheet and the second adhesive sheet, the separation between the first and second adhesive sheets is performed in the peeling process by peeling at the interface between the second thermoplastic resin layer of the first adhesive sheet and the second thermoplastic resin layer of the second adhesive sheet. If an intermediate protective layer is placed between the first and second adhesive sheets, the separation between the first and second adhesive sheets is performed in the peeling process by peeling at the interface between the second thermoplastic resin layer of the first adhesive sheet and the intermediate protective film, and at the interface between the second thermoplastic resin layer of the second adhesive sheet and the intermediate protective film. [Effects of the Invention]

[0015] In the method of the present invention, the thermoplastic resin layer of the adhesive sheet does not come into contact with the heat-pressure bonding means such as a heat roll, thus preventing problems such as the thermoplastic resin layer fusing to the heat-pressure bonding means. Furthermore, since two single-sided metal laminates can be obtained simultaneously in a single heat lamination process, the productivity of single-sided metal-clad laminates can be significantly improved. [Brief explanation of the drawing]

[0016] [Figure 1] This is a cross-sectional view of a single-sided metal-clad laminate according to one embodiment. [Figure 2] This is a schematic cross-sectional view illustrating an example of the manufacturing process for a single-sided metal-clad laminate. [Figure 3] This is a schematic cross-sectional view illustrating an example of the manufacturing process for a single-sided metal-clad laminate. [Figure 4] This is a schematic cross-sectional view illustrating an example of the manufacturing process for a single-sided metal-clad laminate. [Figure 5] This is a schematic cross-sectional view illustrating an example of the manufacturing process for a single-sided metal-clad laminate. [Modes for carrying out the invention]

[0017] FIG. 1 is a cross-sectional view showing the laminated structure of a single-sided metal-clad laminate. The single-sided metal-clad laminate 20 includes a metal foil 5 closely laminated on one surface of an adhesive sheet 1. The adhesive sheet 1 is a multilayer film having thermoplastic resin layers 11 and 12 that function as adhesive layers on both surfaces of a core layer 10. In the single-sided metal-clad laminate 20, the metal foil 5 is laminated on the first thermoplastic resin layer 11 on one surface of the adhesive sheet 1. A metal foil is not provided on the second thermoplastic resin layer 12 on the other surface of the adhesive sheet 1, and the thermoplastic resin layer 12 is exposed.

[0018] <舍 Hereinafter, the main surface on the side where the metal foil of the adhesive sheet is disposed will be referred to as the "first main surface", and the surface on the side where the metal foil is not disposed will be referred to as the "second main surface". In some cases, the main surface of the metal foil to be bonded to the adhesive sheet will be referred to as the "first main surface", and the other main surface will be referred to as the "second main surface". Also, the thermoplastic resin layer 11 provided on the first main surface of the core layer 10 may be referred to as the "first thermoplastic resin layer", and the thermoplastic resin layer 12 provided on the second main surface of the core layer 10 may be referred to as the "second thermoplastic resin layer".

[0019] FIGS. 2A to 2C are cross-sectional views schematically showing the manufacturing process of a single-sided metal-clad laminate according to an embodiment of the present invention. In the present invention, heat lamination is performed in a state where two adhesive sheets 101 and 102 and two metal foils 151 and 152 are overlapped to produce a laminate 502 (FIGS. 2A and 2B: lamination process), and peeling is performed between the two adhesive sheets 101 and 102 (FIG. 2C: peeling process). As a result, a first single-sided metal-clad laminate 121 in which the first metal foil 151 is bonded to the thermoplastic resin layer 111 on the first main surface of the first adhesive sheet 101, and a second single-sided metal-clad laminate 122 in which the second metal foil 152 is bonded to the thermoplastic resin layer 121 on the first main surface of the second adhesive sheet 102 are simultaneously obtained. That is, according to the method of the present invention, two single-sided metal-clad laminates can be obtained by one heat lamination.

[0020] [Components of Single-Sided Metal-Clad Laminate] As described above, the single-sided metal-clad laminate includes a metal foil 5 on one surface of the adhesive sheet 1.

[0021] [Adhesive Sheet] It should be noted that there seems to be a misspelling in the original text where "舍0000087" should probably be " ". This has been retained as is in the translation. The adhesive sheet 1 is a multilayer film comprising thermoplastic resin layers 11 and 12 that function as adhesive layers on both sides of a core layer 10.

[0022] (Core layer) The core layer 10 is required to withstand the heating temperatures during the heat lamination process in the manufacturing of the FPC. Therefore, a high heat-resistant film is used as the core layer 10. As the resin material for the core layer 10, polyimide film and polyethylene naphthalate film are preferred, and among these, non-thermoplastic resin materials that do not have thermoplastic properties are preferred. Non-thermoplastic polyimide film is preferred as the core layer 10 because it has high heat resistance and excellent electrical properties. The core layer 10 preferably contains 80% by weight or more of non-thermoplastic polyimide, and more preferably contains 90% by weight or more.

[0023] "Non-thermoplastic polyimides" are polyimides that do not soften when heated and do not exhibit adhesive properties. Specifically, polyimides that maintain their shape without wrinkling or stretching when a single layer of polyimide film is heated at 380°C for 2 minutes are included in "non-thermoplastic polyimides." Polyimides that substantially do not exhibit a glass transition temperature are also included in non-thermoplastic polyimides. The glass transition temperature is the temperature at which the storage modulus, measured by a dynamic viscoelasticity analyzer (DMA), shows an inflection point. A resin material that "substantially does not have a glass transition temperature" refers to one that begins thermal decomposition before reaching the glass transition state.

[0024] Polyimides are generally obtained by preparing a polyimide precursor (polyamic acid) by polymerization of a diamine and a tetracarboxylic dianhydride, and then imidizing the polyamic acid by dehydration and cyclization. In the preparation of non-thermoplastic polyimides, a combination of an aromatic diamine and an aromatic tetracarboxylic dianhydride is preferably used as the monomer.

[0025] Aromatic diamines include 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2-bis{4-(4-aminophenoxy)phenyl}propane, 2,2-bis{4-(4-aminophenoxy)phenyl}hexafluoropropane, bis{4-(3-aminophenoxy)phenyl}sulfone, bis{4-(4-aminophenoxy)phenyl}sulfone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, and 3,3'-dichlorobenzo Examples include diaminobenzoidine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 1,4-diaminobenzene(p-phenylenediamine), 1,3-diaminobenzene(m-phenylenediamine), 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 9,9-bis(4-aminophenyl)fluorene, 4,4'-(1,4-phenylenebis(1-methylethylidene))bisaniline, 4,4'-(1,3-phenylenebis(1-methylethylidene))bisaniline, 4,4'-diaminobenzanilide, and 2,2'-dimethylbiphenyl-4,4'-diamine. Two or more aromatic diamines may also be used.

[0026] Aromatic tetracarboxylic dianhydrides include 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic acid dianhydride, 3,4'-oxyphthalic acid dianhydride, ethylenebis(trimellitic acid monoester acid anhydride), bisphenol A bis(trimellitic acid monoester acid anhydride), pyromellitic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, and 3,3',4,4 Examples include aromatic tetracarboxylic dianhydrides such as '-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3',4,4'-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 4,4'-hexafluoroisopropylidene diphthalic acid anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, p-phenylenebis(trimellitic acid monoester anhydride), and p-phenylenediphthalic acid anhydride. Two or more aromatic tetracarboxylic dianhydrides may also be used.

[0027] Polyamic acid is obtained by reacting a diamine with a tetracarboxylic dianhydride in substantially equimolar amounts. The order of addition, the combination of monomers, and the composition are not particularly limited. The organic solvent used for polymerization of polyamic acid is not particularly limited as long as it dissolves the diamine, tetracarboxylic dianhydride, and polyamic acid. Preferred organic solvents include amide solvents such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. The polymerization temperature is preferably -10°C to 50°C. The reaction time is not particularly limited, but is usually several minutes to several hours. The solid content concentration of the polyamic acid solution is usually 5 to 35% by weight, preferably 10 to 30% by weight.

[0028] Polyimides can be obtained by imidizing (dehydrating and cyclizing) polyamic acid, which serves as a polyimide precursor. A curing agent may be added to the polyamic acid solution during imidation. Examples of curing agents include dehydrating agents and imidation catalysts. Examples of dehydrating agents include aliphatic anhydrides, aromatic anhydrides, N,N'-dialkylcarbodiimides, lower aliphatic halides, halogenated lower aliphatic anhydrides, arylsulfonic acid dihalides, and thionyl halides. Examples of imidation catalysts include aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines.

[0029] The core layer may contain a filler in addition to the non-thermoplastic polyimide resin. Examples of filler materials include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

[0030] (thermoplastic resin layer) Examples of materials for the thermoplastic resin layers 11 and 12 provided on both sides of the core layer 10 include polycarbonate resins, acrylonitrile-styrene copolymer resins, and thermoplastic polyimide resins. In particular, from the viewpoint of heat resistance and adhesion to the core layer, the thermoplastic resin layers 11 and 12 preferably contain thermoplastic polyimide resin, and preferably contain 50% by weight or more of thermoplastic polyimide resin.

[0031] The thermoplastic resin layer 11 provided on the first main surface of the core layer 10 and the thermoplastic resin layer 12 provided on the second main surface of the core layer 10 may have the same composition or different compositions. From the viewpoint of suppressing warping of the adhesive sheet and the single-sided metal-clad laminate, and simplifying the manufacturing process, it is preferable that the thermoplastic resin layers 11 and 12 provided on both sides of the core layer have the same composition.

[0032] From the viewpoint of adhesion to the metal foil 5 and heat resistance, it is preferable that the thermoplastic resin layers 11 and 12 have a glass transition temperature in the range of 150°C to 320°C. The glass transition temperature of the thermoplastic resin layers 11 and 12 may be 200°C to 300°C. The glass transition temperature is the temperature at which the storage modulus measured by a dynamic viscoelasticity analyzer (DMA) shows an inflection point.

[0033] Thermoplastic polyimides, like non-thermoplastic polyimides, are obtained by dehydration and cyclization of polyamic acid as a polyimide precursor. In the preparation of thermoplastic polyimides, a combination of aromatic diamines and aromatic tetracarboxylic dianhydrides is preferably used as monomers. The properties of the polyimide can be adjusted by selecting the diamine and tetracarboxylic dianhydride.

[0034] Generally, as the proportion of rigid aromatic diamines used increases, the glass transition temperature rises, which in turn increases the elastic modulus at high temperatures and tends to decrease adhesion and processability. Examples of thermoplastic polyimide resin compositions include those using benzophenone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, oxydiphthalic acid dianhydride, biphenyl sulfone tetracarboxylic dianhydride, etc., as the tetracarboxylic dianhydride, and aromatic diamines having an aminophenoxy group as the diamine. The proportion of rigid aromatic diamines used in the diamines used in the preparation of thermoplastic polyimide is preferably 40 mol% or less, more preferably 30 mol% or less, and even more preferably 20 mol% or less.

[0035] (Preparation of adhesive sheets) The method for producing an adhesive sheet having thermoplastic resin layers 11 and 12 on both sides of a core layer 10 is not particularly limited. For example, a method in which thermoplastic resin layers are formed sequentially or simultaneously on both main surfaces of the core layer 10; or a method in which the material for the core layer 10 and the materials for the thermoplastic resin layers 11 and 12 are co-extruded in a multilayer die.

[0036] Polyimides obtained by imidizing polyamic acids, which are produced by polymerization of aromatic diamines and aromatic tetracarboxylic dianhydrides, have low solubility in organic solvents after imidization. Therefore, when the core layer 10 and thermoplastic resin layers 11 and 12 are polyimides, it is preferable to form a polyamic acid solution (polyimide precursor) into a film before performing imidization.

[0037] When producing a multilayer polyimide film comprising a non-thermoplastic polyimide core layer 10 with thermoplastic polyimide layers 11 and 12 on both sides by multilayer co-extrusion, it is preferable to apply a polyamic acid solution as a precursor for the non-thermoplastic polyimide constituting the core layer 10 and a polyamic acid solution as a precursor for the thermoplastic polyimide constituting the thermoplastic resin layers 11 and 12 in a film-like manner onto a support substrate by three-layer co-extrusion, remove the solvent by heating as necessary, and then heat again to perform imidization. As mentioned above, a curing agent may be added to the polyamic acid solution to promote imidization. In the case of three-layer co-extrusion, the curing agent may be added only to the polyimide precursor of the core layer 10, or it may be added to both the polyimide precursor of the core layer 10 and the polyimide precursors of the thermoplastic resin layers 11 and 12. The polyimides of the core layer 10 and the thermoplastic resin layers 11 and 12 may be completely imidized, or they may contain some unimidized structures (polyamic acid in an open ring state).

[0038] The thickness of the core layer 10 and the thermoplastic resin layers 11 and 12 are not particularly limited, but it is preferable to adjust the balance of the thicknesses by considering the coefficient of thermal expansion of each layer, etc., so that warping does not occur in the multilayer film state.

[0039] The thickness of the core layer 10 is preferably 3 to 50 μm, and more preferably 5 to 40 μm. The thickness of each of the thermoplastic resin layers 11 and 12 is preferably 0.5 to 15 μm, and more preferably 1 to 10 μm. The thicknesses of the thermoplastic resin layers 11 and 12 provided on both sides of the core layer 10 may be the same or different. From the viewpoint of suppressing warping, it is preferable that the difference between the thickness of the thermoplastic resin layer 11 and the thickness of the thermoplastic resin layer 12 be small. The ratio of the thickness of the thermoplastic resin layer 11 to the thickness of the thermoplastic resin layer 12 is preferably 0.7 to 1.3, more preferably 0.8 to 1.2, and even more preferably 0.9 to 1.1.

[0040] The thickness of each thermoplastic resin layer 11 and 12 is preferably 0.05 to 0.5 times the thickness of the core layer 10, and may be approximately 0.1 to 0.4 times. The total thickness of the adhesive sheet 1 is preferably 5 to 50 μm. If the thickness is within this range, it can be suitably used as a substrate for FPC.

[0041] Commercially available multilayer films with thermoplastic resin layers on both sides of the core layer may also be used. For example, Kaneka's "Pixio" series is a three-layer multilayer polyimide film with thermoplastic polyimide layers on both sides of a non-thermoplastic polyimide core layer.

[0042] The adhesive sheet 1 preferably has a tensile modulus of 0.05 to 1.5 GPa at a temperature of 350°C. If the modulus of elasticity of the adhesive sheet 1 at the temperature during heat lamination is excessively high, the adhesive sheet will be too hard and lack sufficient cushioning against the lamination pressure, which can lead to defects in appearance such as wrinkles during lamination. On the other hand, if the modulus of elasticity of the adhesive sheet 1 at the temperature during heat lamination is excessively low, the adhesive sheet will be easily deformed by the lamination pressure, which can easily lead to defects in appearance such as the transfer of fine scratches from the surface of the heat roll or protective film, or dents caused by foreign matter.

[0043] The tensile modulus of the adhesive sheet 1 at a temperature of 350°C being within the above range suppresses appearance defects caused by wrinkles and deformation during heat lamination. The tensile modulus of the adhesive sheet at a temperature of 350°C is more preferably 0.08 to 1 GPa, even more preferably 0.1 to 0.7 GPa, and may also be 0.12 to 0.6 GPa or 0.14 to 0.5 GPa.

[0044] Since the glass transition temperatures of the thermoplastic resin layers 11 and 12 of the adhesive sheet 1, which is a multilayer film, are generally below 350°C, the tensile modulus at 350°C is greatly influenced by the properties of the core layer 10. When the core layer 10 is a non-thermoplastic polyimide film, the higher the proportion of monomers with a rigid structure in the monomer components (tetracarboxylic dianhydride and diamine) that make up the polyimide, the greater the tensile modulus at 350°C tends to be.

[0045] A typical example of a tetracarboxylic dianhydride with a rigid structure is pyromellitic dianhydride (PMDA), and a typical example of a diamine with a rigid structure is p-phenylenediamine (PDA). The higher the proportion of PMDA in the tetracarboxylic dianhydride component and the higher the proportion of PDA in the diamine component that constitutes polyimide, the greater the tensile modulus at 350°C tends to be.

[0046] <Metal foil> As the metallic material for the metal foil 5, copper or copper alloys, stainless steel or its alloys, nickel or nickel alloys (including 42 alloys), aluminum or aluminum alloys are preferred due to their high conductivity. Metal foil is preferred for the metal foil 5 because it is easy to laminate, and copper foil such as rolled copper foil or electrolytic copper foil is preferred, as with general FPCs. The surface of the metal foil may be provided with a rust-preventive layer, a heat-resistant layer, an adhesive layer, etc. The thickness of the metal foil 5 is not particularly limited and should be selected according to the configuration of the FPC and the required conductivity. The thickness of the metal foil 5 is, for example, 3 to 30 μm, and 5 to 20 μm is preferred. From the viewpoint of adhesion to the thermoplastic resin layer, the surface roughness (Rz) of the metal foil 5 is preferably 0.01 μm to 1 μm.

[0047] [Manufacturing method for single-sided metal-clad laminated boards] As shown in Figures 2A-C, a laminate 502 is fabricated by heat lamination with two adhesive sheets 101 and 102 and two metal foils 151 and 152 stacked on top of each other (lamination process), and then peeling is performed between the two adhesive sheets (peeling process). Through these processes, two single-sided metal-clad laminates 121 and 122 are obtained.

[0048] <Lamination process> First, the first metal foil 151, the first adhesive sheet 101, the second adhesive sheet 102, and the second metal foil 152 are arranged in this order along a direction perpendicular to the sheet surface (Figure 2A). The first metal foil 151 is a metal foil that is bonded to the thermoplastic resin layer 111 of the first main surface of the first adhesive sheet 101, and the second metal foil 152 is a metal foil that is bonded to the thermoplastic resin layer 121 of the first main surface of the second adhesive sheet 102.

[0049] In this state, the thermoplastic resin layer 111 of the first main surface of the first adhesive sheet 101 faces the first main surface of the first metal foil 151, the thermoplastic resin layer 121 of the first main surface of the second adhesive sheet 102 faces the first main surface of the first metal foil 152, and the thermoplastic resin layer 112 of the second main surface of the first adhesive sheet 101 faces the thermoplastic resin layer 122 of the second main surface of the second adhesive sheet 102.

[0050] In this specification, "facing" means that two surfaces are arranged facing each other, and other layers may be interposed between the two surfaces. For example, as will be described later, an intermediate protective film 71 may be placed between the first adhesive sheet 101 and the second adhesive sheet 102 (see Figures 3A and 5A). In this case, the intermediate protective film 71 is placed between the thermoplastic resin layer 112 of the second main surface of the first adhesive sheet 101 and the thermoplastic resin layer 122 of the second main surface of the second adhesive sheet 102, but since the second main surface of the first adhesive sheet 101 and the second main surface of the second adhesive sheet 102 are arranged facing each other, the second main surface of the first adhesive sheet 101 and the second main surface of the second adhesive sheet 102 are facing each other.

[0051] With the first metal foil 151, first adhesive sheet 101, second adhesive sheet 102, and second metal foil 152 arranged in this order, heat lamination is performed by applying pressure from the second main surface side of the first metal foil 151 and the second main surface of the second metal foil 152, thereby forming a laminate 502 in which the first metal foil 151, first adhesive sheet 101, second adhesive sheet 102, and second metal foil 152 are stacked (Figure 2B).

[0052] Examples of thermal lamination (thermocompression bonding) include batch thermal lamination using a single-sheet press, continuous processing using a double-belt press (DBP) device, and thermal lamination using a hot roll. From the viewpoint of productivity, a method of thermal lamination using a roll-to-roll method with a thermal roll laminating device equipped with a hot roll for heating and pressurizing the material is preferred. The thermal roll laminating device is equipped with one or more pairs (two) of hot rolls, and thermal lamination is performed by clamping the object to be laminated between the two hot rolls and heating and pressurizing it. Since heating and temperature control are easy, the nip rolls are preferably metal rolls.

[0053] From the viewpoint of adhesion (peel strength) between the adhesive film and metal foil in a single-sided metal-clad laminate, dimensional stability of the single-sided metal-clad laminate, and suppression of warping, it is preferable that the heating temperature during heat lamination be above the glass transition temperature (Tg) of the thermoplastic resin layer of the adhesive sheet. By heating above the glass transition temperature of the thermoplastic resin layers 111 and 121 and heat-pressing them, the thermoplastic resin layer 111 of the first adhesive sheet 101 and the first metal foil 151 are bonded, and the thermoplastic resin layer 121 of the second adhesive sheet 102 and the first metal foil 152 are bonded. The heating temperature is preferably (Tg+0)℃ to (Tg+180)℃, more preferably (Tg+10)℃ to (Tg+160)℃, and may also be (Tg+20)℃ to (Tg+150)℃. The heating temperature may also be 280 to 400℃, 300 to 380℃, or 320 to 370℃.

[0054] <Peeling process> Through the lamination process described above, a laminate 502 is formed in which a first single-sided metal-clad laminate 121, formed by laminating a first adhesive sheet 101 and a first metal foil 151, and a second single-sided metal-clad laminate 122, formed by laminating a second adhesive sheet 102 and a second metal foil 152, are closely laminated via the thermoplastic resin layer 112 on the second main surface of the first adhesive sheet 101 and the thermoplastic resin layer 122 on the second main surface of the second adhesive sheet 102 (Figure 2B). By peeling and separating this laminate 502 between the first adhesive film 101 and the second adhesive film 102, two single-sided metal-clad laminates 121 and 122 are obtained.

[0055] In the laminate shown in Figure 2B, the adhesive sheets and metal foils are firmly bonded at the interface between the thermoplastic resin layer 111 on the first main surface of the first adhesive sheet 101 and the first metal foil 151, and at the interface between the thermoplastic resin layer 121 on the first main surface of the second adhesive sheet 102 and the second metal foil 152. However, the adhesive force at the interface between the thermoplastic resin layer 112 on the second main surface of the first adhesive sheet 101 and the thermoplastic resin layer 122 on the second main surface of the second adhesive sheet 102 is small, so the laminate 502 can be easily peeled apart from the first adhesive sheet and the second adhesive sheet.

[0056] In the above manufacturing method, the second main surfaces of the two adhesive sheets 101 and 102 are arranged to face each other in the laminate 502, and the thermoplastic resin layers 112 and 122 of the second main surfaces of the adhesive sheets do not come into contact with the heat-pressure bonding means such as a heat roll, thus preventing problems such as the thermoplastic resin layer fusing to the heat-pressure bonding means. Furthermore, since the laminate 502 is formed by a single heat lamination and separated between the adhesive sheets 101 and 102, two single-sided metal laminates are obtained simultaneously, doubling the productivity of single-sided metal-clad laminates.

[0057] <Process using thermal roll lamination> As described above, it is preferable to perform thermal lamination using a thermal roll laminating apparatus that performs thermal compression bonding with a hot roll. Thermal roll lamination offers excellent productivity because it performs thermal lamination while continuously conveying the first metal foil 151, first adhesive sheet 101, second adhesive sheet 102, and second metal foil 152 that constitute the laminate 502.

[0058] A heat roll laminating apparatus is typically equipped with a feeding mechanism upstream of the heat rolls used as a heat-compression bonding means, which unwinds the laminated material from the winding body of each laminate to be laminated material and continuously feeds it out, and a winding mechanism downstream of the heat rolls, which winds the laminated material onto the winding body. A specific example of the feeding mechanism and winding mechanism is a roll winding machine.

[0059] The laminate 502 formed by heat roll lamination may be wound up by a winding means while the two single-sided metal-clad laminates are still laminated together, or a peeling process may be performed after heat lamination to separate the two single-sided metal-clad laminates, and then each of the two single-sided metal-clad laminates 121 and 122 may be wound up by a winding means.

[0060] [Differential examples of layered configurations] In the embodiments shown in Figures 2A to C, no other layer is placed between the first adhesive sheet 101 and the second adhesive sheet 102. The lamination process forms a laminate 502 in which the thermoplastic resin layer 112 of the second main surface of the first adhesive sheet 101 and the thermoplastic resin layer 122 of the second main surface of the second adhesive sheet 102 are in contact. The laminate obtained by the lamination process may have an intermediate protective film 71 placed between the thermoplastic resin layer 112 of the second main surface of the first adhesive sheet 101 and the thermoplastic resin layer 122 of the second main surface of the second adhesive sheet 102.

[0061] For example, as shown in Figure 3A, by performing thermal lamination with an intermediate protective film 71 placed between the first adhesive sheet 101 and the second adhesive sheet 102, a laminate 503 is obtained as shown in Figure 3B, in which the thermoplastic resin layer 112 of the second main surface of the first adhesive sheet 101 is in contact with one side (first main surface) of the intermediate protective film 71, and the thermoplastic resin layer 122 of the second main surface of the second adhesive sheet 102 is in contact with the other side (second main surface) of the intermediate protective film 71.

[0062] When an intermediate protective film 71 is placed between the first adhesive sheet 101 and the second adhesive sheet 102, the peeling process is performed by peeling at the interface between the thermoplastic resin layer 112 on the second main surface of the first adhesive sheet 101 and the intermediate protective film 71, and at the interface between the thermoplastic resin layer 122 on the second main surface of the second adhesive sheet 102 and the intermediate protective film 71.

[0063] In this embodiment, the second thermoplastic resin layer 112 of the first adhesive sheet 101 and the second thermoplastic resin layer 122 of the second adhesive sheet 102 do not come into contact. Therefore, even if the adhesive strength of the thermoplastic resin layers of the adhesive sheets is high, the thermoplastic resin layers 112 and 122 of the two adhesive sheets 101 and 102 do not adhere to each other, making it possible to perform the peeling process stably.

[0064] In the lamination process, a surface protection material may be placed between the heat-pressure bonding means (not shown), such as a heat roll, and the metal foils 151 and 152. For example, as shown in Figure 4A, by placing the first surface protection film 91 on the second main surface of the first metal foil 151 and the second surface protection film 92 on the second main surface of the second metal foil 152, and then performing heat lamination, a laminate 504 is obtained in which the first surface protection film 91 is laminated on the second main surface of the first metal foil 151 and the second surface protection film 92 is laminated on the second main surface of the second metal foil 152, as shown in Figure 4B.

[0065] When surface protection films 91 and 92 are placed on the second main surfaces of metal foils 151 and 152, in the peeling process, peeling is performed not only between the first adhesive sheet 151 and the second adhesive sheet 152, but also at the interface between the first metal foil 151 and the first surface protection film 91, and at the interface between the second metal foil 152 and the second surface protection film 92, thereby peeling and removing the surface protection film from the surface of the single-sided metal-clad laminate.

[0066] In this embodiment, surface protective films 91 and 92 are placed between the heat-pressure bonding means, such as a heat roll, and the metal foils 151 and 152 during heat lamination. Since the heat-pressure bonding means and the metal foils do not come into direct contact, it is possible to reduce appearance defects such as scratches on the metal foils during heat bonding.

[0067] Figures 4A to 4C show a configuration in which surface protection films 91 and 92 are placed on metal foils 151 and 152 on both sides, but the surface protection film may also be placed on only one side of the metal foil. As shown in Figure 4B, when the laminated body 504 after heat lamination has a symmetrical laminated structure, warping of the laminated body and the single-sided metal-clad laminate tends to be suppressed. Therefore, when placing a surface protection film on metal foil, it is preferable to place the surface protection films 91 and 92 on both sides of the metal foil, as shown in Figures 4A to 4C.

[0068] As shown in Figure 5A, an intermediate protective film 71 may be placed between the first adhesive sheet 101 and the second adhesive sheet 102, and further, a first surface protective film 91 may be placed on the second main surface of the first metal foil 151, and a second surface protective film 92 may be placed on the second main surface of the second metal foil 152 before heat lamination. In this embodiment, the laminated body 505 after heat lamination has a structure in which the first surface protective film 91 / first adhesive sheet 101 / intermediate protective film 71 / second adhesive sheet 102 / second surface protective film 92 are laminated in that order, as shown in Figure 4B.

[0069] By peeling and separating this laminate 505 at the interface between the first surface protective film 91 and the first metal foil 151, the interface between the second surface protective film 92 and the second metal foil 152, the interface between the first adhesive sheet 101 and the intermediate protective film 71, and the interface between the second adhesive sheet 102 and the intermediate protective film 71, two single-sided metal-clad laminates 101 and 102 are obtained, as shown in Figure 5C.

[0070] <Protective film> The surface protective films 91 and 92 placed on the surface of the metal foil, and the intermediate protective film 71 placed between the two adhesive sheets, may have functions such as preventing fusion of the thermoplastic resin layer between the heat-pressure bonding means and the adhesive sheet, preventing excessive fusion of the thermoplastic resin layers with each other, and preventing wrinkle formation during heat lamination.

[0071] These protective films are not particularly limited as long as they can withstand the heating temperature during heat sealing, and heat-resistant resin films such as non-thermoplastic polyimide films, and metal foils such as copper foil, aluminum foil, and SUS foil are preferably used. Among these, non-thermoplastic polyimide films are particularly preferred from the viewpoint of heat resistance and recyclability. From the viewpoint of handling and preventing wrinkles during lamination, the thickness of the protective film is preferably 25 to 300 μm, more preferably 50 to 250 μm, and may also be 75 to 200 μm.

[0072] When using a non-thermoplastic polyimide film as a protective film, various known films can be used. For example, commercially available polyimide films such as Kaneka's "Apical" series, Ube Industries' "Upirex" series, and Toray DuPont's "Kapton" series may be used.

[0073] When the process using the protective film shown in Figures 3-5 is carried out using a hot roll laminating apparatus, the protective film can be continuously fed from the feeding means and heat-pressed together with the metal foil and adhesive sheet using a hot roll. After the peeling process, the protective film peeled from the single-sided metal-clad laminate is wound into a roll by the winding means. This protective film may be reused. When reusing the protective film, it is preferable to wind it so that the positions of both ends in the width direction of the protective film are constant. To align the positions of both ends in the width direction of the film, end position detection means and winding position correction means may be provided on the pass line of the hot roll laminating apparatus.

[0074] [Flexible Printed Circuit Board] The single-sided metal-clad laminate 20 described above is suitably used in the manufacture of flexible printed circuit boards (FPCs). The FPC may be a multilayer printed circuit board in which multiple wiring layers are laminated with insulating layers in between. In a multilayer printed circuit board, the adhesive sheet 1 serves as the insulating layer between the multiple wiring layers.

[0075] A wiring layer (first wiring layer) is formed by patterning the metal foil 5 of the single-sided metal-clad laminate 20. Multilayering is performed by laminating this single-sided wiring substrate with a substrate containing another wiring layer (second wiring layer). For example, multilayering is performed by bonding the non-wiring layer surface (second thermoplastic resin layer 12) of the single-sided metal-clad laminate having the first wiring layer formed by patterning the metal foil 5 to the wiring layer (second wiring layer) of another substrate. The thermoplastic resin layer 12 of the adhesive sheet 1 and the wiring layer of the other substrate may be bonded via an adhesive sheet such as a bonding sheet. [Examples]

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0077] [Fabrication of multilayer polyimide films] <Manufacturing Example 1> (Preparation of polyamic acid solution for the core layer) While maintaining the reaction system in a nitrogen atmosphere at 20°C, N,N-dimethylformamide (DMF) was stirred and the diamine and tetracarboxylic anhydride were sequentially added in the molar ratios shown in Table 1 to obtain polyamic acid solution A with a viscosity of 3000 poise.

[0078] (Preparation of polyamic acid solution for thermoplastic resin layer) While maintaining the reaction system in a nitrogen atmosphere at 20°C, the diamine and tetracarboxylic anhydride were sequentially added to the DMF while stirring, in the molar ratios shown in Table 1, to obtain polyamic acid solution B with a viscosity of 1000 poise.

[0079] (Film formation and imidization) To 100 parts by weight of polyamic acid solution A, 50 parts by weight of a curing agent solution containing acetic anhydride / isoquinoline / DMF in a weight ratio of 33 / 10 / 57 was added, and the mixture was stirred and degassed at 0°C or below to obtain a solution for forming the core layer. Polyamic acid solution B was diluted by adding DMF to a solid content concentration of 10% by weight, and the mixture was stirred and degassed at 0°C or below to obtain a solution for forming the thermoplastic resin layer.

[0080] Using a triple-coating apparatus, three layers of thermoplastic resin layer-forming solution (dry thickness 4 μm), core layer-forming solution (dry thickness 17 μm), and thermoplastic resin layer-forming solution (dry thickness 4 μm) were applied to a metal belt. After heating at 110°C for 180 seconds, the self-supporting gel film was peeled off the metal belt. Subsequently, heating at 300°C for 56 seconds and 380°C for 49 seconds was performed to obtain a multilayer polyimide film 1 with a total thickness of 25 μm, having thermoplastic polyimide layers on both sides of a core layer made of non-thermoplastic polyimide.

[0081] <Manufacturing Example 2> While maintaining the reaction system in a nitrogen atmosphere at 20°C, the DMF was stirred and the diamine and tetracarboxylic anhydride were sequentially added in the molar ratios shown in Table 1 to obtain polyamic acid solution C with a viscosity of 2000 poise. A multilayer polyimide film 2 with a total thickness of 25 μm was obtained in the same manner as in Production Example 1, except that polyamic acid solution C was used instead of polyamic acid solution A as the core layer forming solution.

[0082] <Manufacturing Example 3> While maintaining the reaction system in a nitrogen atmosphere at 20°C, the diamine and tetracarboxylic anhydride were sequentially added to the DMF while stirring, in the molar ratios shown in Table 1, to obtain polyamic acid solution D with a viscosity of 1500 poise and polyamic acid solution E with a viscosity of 1000 poise.

[0083] Polyamide acid solution D was used instead of polyamide acid solution A as the core layer forming solution, and polyamide acid solution E was used instead of polyamide acid solution B as the thermoplastic resin layer forming solution. The composition of the curing agent solution added to the core layer forming solution was changed to acetic anhydride / isoquinoline / DMF = 42 / 21 / 37. Otherwise, the process was the same as in Production Example 1 to obtain a multilayer polyimide film 3 with a total thickness of 25 μm.

[0084] <Evaluation of multilayer polyimide films> The tensile modulus of the multilayer polyimide films obtained in Production Examples 1-3 was measured at 350°C using a tensile testing machine. Furthermore, single-layer polyimide films with a thickness of approximately 10 μm were prepared using polyamic acid solution B and polyamic acid solution D, and dynamic viscoelasticity measurements were performed. The temperature at which the storage modulus inflects was defined as the glass transition temperature of the thermoplastic polyimide.

[0085] Table 1 shows the composition of the core layer and thermoplastic resin layer in the multilayer polyimide films of Production Examples 1 to 3, as well as the glass transition temperature (Tg) of the thermoplastic resin layer and the tensile modulus of the multilayer film at 350°C. In Table 1, diamines and tetracarboxylic dianhydrides are indicated by the following abbreviations.

[0086] <Diamine> PDA: p-phenylenediamine TPE-R: 1,3-bis(4-aminophenoxy)benzene ODA: 4,4'-oxydianiline BAPP: 2,2-Bis[4-(4-aminophenoxy)phenyl]propane m-TB: 4,4'-diamino-2,2'-dimethylbiphenyl <Tetracarboxylic acid dianhydride> PMDA: Pyromellitic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride BTDA:3,3',4,4'-benzophenonetetracarboxylic dianhydride ODPA: 4,4'-Oxydiphthalic anhydride

[0087] [Table 1]

[0088] [Example 1] Using a multilayer polyimide film 1 as the adhesive sheet and a 12 μm thick rolled copper foil (JX Metals "GHY5-93F-HA-V2") as the metal foil, a laminate configuration of copper foil / adhesive sheet / adhesive sheet / copper foil was used, as shown in Figure 2. Thermal lamination was performed using a hot roll laminating apparatus under the conditions of a lamination temperature of 360°C, a lamination pressure of 244 N / cm, and a lamination speed of 1 m / min. After delamination between the two adhesive sheets, two single-sided copper-clad laminates were obtained.

[0089] [Example 2] A multilayer polyimide film 1 was used as the adhesive sheet, and as shown in Figure 4, a laminated structure of protective film / copper foil / adhesive sheet / adhesive sheet / copper foil / protective film was used. After thermal lamination was performed using a hot roll laminating apparatus under the same conditions as in Example 1, the two adhesive sheets were peeled apart and between the copper foil and the protective film to obtain two single-sided copper-clad laminates. A non-thermoplastic polyimide film (Kaneka "Apical 125NPI") was used as the surface protective film placed on the outside of the upper and lower rolled copper foils.

[0090] [Example 3] A single-sided copper-clad laminate was obtained in the same manner as in Example 1, except that a multilayer polyimide film 2 was used as the adhesive sheet.

[0091] [Example 4] A single-sided copper-clad laminate was obtained in the same manner as in Example 1, except that a multilayer polyimide film 3 was used as the adhesive sheet.

[0092] [Comparative Example 1] Using a multilayer polyimide film 1 as the adhesive sheet, we attempted to perform thermal lamination with a copper foil / adhesive sheet laminate configuration using a thermal roll laminating apparatus under the same conditions as in Example 1. However, the adhesive sheet stuck to the thermal roll, and we were unable to obtain a single-sided copper-clad laminate.

[0093] [Comparative Example 2] A multilayer polyimide film 1 was used as the adhesive sheet, and a laminated structure of copper foil / adhesive sheet / protective film was formed. After thermal lamination using a hot roll laminating apparatus under the same conditions as in Example 1, the laminate was peeled off between the copper foil and the protective film to obtain a single-sided copper-clad laminate. A non-thermoplastic polyimide film (Kaneka "Apical 50AH") was used as the protective film.

[0094] [Comparative Example 3] A single-sided copper-clad laminate was obtained in the same manner as in Comparative Example 2, except that a multilayer polyimide film 2 was used as the adhesive sheet.

[0095] [Comparative Example 4] A single-sided copper-clad laminate was obtained in the same manner as in Comparative Example 2, except that a multilayer polyimide film 3 was used as the adhesive sheet.

[0096] [evaluation] <Peel strength of copper foil> A 1mm wide masking tape was applied to the surface of the copper foil of a single-sided copper-clad laminate, and the copper foil was etched using a ferric chloride aqueous solution to form a 1mm wide copper foil pattern. The peel strength of the copper foil pattern was measured using a tensile testing machine under conditions of a peel angle of 90° and a peel speed of 50mm / min.

[0097] <curve> A single-sided copper-clad laminate was cut into a 5cm x 5cm square and placed on a horizontal surface with the copper foil-laminated side facing upwards. The distance from the surface (amount of lift) was measured at each of the four vertices of the square, and the average value was defined as the amount of warping.

[0098] <Exterior> The copper foil side and adhesive sheet side of the obtained single-sided copper-clad laminates were visually observed under fluorescent light. Those with no wrinkles or streaks on either side were designated as A, and those with wrinkles or streaks on either side were designated as B.

[0099] Table 2 shows the types of adhesive sheets (multilayer polyimide films) used in the examples and comparative examples, their tensile modulus at 350°C, the lamination configuration during thermal lamination, and the evaluation results of the single-sided copper-clad laminates.

[0100] [Table 2]

[0101] In Comparative Example 1, where one multilayer polyimide film (adhesive sheet) and one copper foil were heat-laminated, the thermoplastic resin layer of the multilayer polyimide film adhered to the heat roll, preventing the creation of a single-sided copper temporary laminate. In contrast, in Example 1, where two adhesive sheets and two copper foils were heat-laminated, the thermoplastic resin layer of the multilayer polyimide film did not come into contact with the heat roll, allowing for successful heat lamination without any problems.

[0102] The copper-clad laminate of Example 1, obtained by peeling the heat-laminated laminate at the interface of two adhesive sheets, exhibited high adhesion (peel strength) of the copper foil and low warping, similar to the copper-clad laminate of Comparative Example 2. Similar trends were observed in the comparison between Example 3 and Comparative Example 3, and between Example 4 and Comparative Example 4.

[0103] In Example 1, where two adhesive sheets and two copper foils were heat-laminated, the thermoplastic resin layer of the multilayer polyimide film did not come into contact with the heat roll, so heat lamination was possible without any problems. Furthermore, the copper-clad laminate obtained from Example 1 by peeling the laminated structure at the interface between the two adhesive sheets exhibited high adhesion (peel strength) of the copper foil and low warping, similar to the copper-clad laminate of Comparative Example 2.

[0104] These results show that by thermal laminating two adhesive sheets and two metal foils and peeling them off at the interface of the adhesive layer, it is possible to obtain single-sided copper-clad laminates with properties equivalent to or better than conventional ones, with higher productivity.

[0105] In Examples 3 and 4, the single-sided copper-clad laminates using multilayer polyimide films 2 and 3 showed no wrinkles or streaks, whereas the single-sided copper-clad laminates using multilayer polyimide film 1 in Examples 1 and 2 (and Comparative Example 2) had an inferior appearance. It is thought that multilayer polyimide films 2 and 3 have a lower elastic modulus at high temperatures compared to multilayer polyimide film 1, resulting in higher cushioning during heat lamination, which suppressed the occurrence of wrinkles and streaks. [Explanation of Symbols]

[0106] 1,101,102 Adhesive Sheet (Multilayer Film) 10,110,120 core layers 11,12,111,112,121,122 Thermoplastic resin layer 5,151,152 Metal foil 20,121,121 Single-sided metal-clad laminate 71 Intermediate protective film 91, 92 Surface protective film

Claims

1. A method for manufacturing a single-sided metal-clad laminate comprising: an adhesive sheet comprising a core layer made of a heat-resistant film, a first thermoplastic resin layer provided on the first main surface of the core layer, and a second thermoplastic resin layer provided on the second main surface of the core layer; and a metal foil closely laminated to the first thermoplastic resin layer of the adhesive sheet, A lamination process in which a first metal foil, a first adhesive sheet, a second adhesive sheet, and a second metal foil are arranged such that the first main surface of the first adhesive sheet faces the first main surface of the first metal foil, the second main surface of the first adhesive sheet faces the second main surface of the second adhesive sheet, and the first main surface of the second adhesive sheet faces the first main surface of the second metal foil, and then heat lamination is performed to form a laminate in which the first metal foil, the first adhesive sheet, the second adhesive sheet, and the second metal foil are laminated; and A peeling step of separating the laminate between the first adhesive sheet and the second adhesive sheet, Perform To simultaneously obtain a first single-sided metal-clad laminate in which a first metal foil is closely laminated on the first main surface of the first adhesive sheet, and a second single-sided metal-clad laminate in which a second metal foil is closely laminated on the first main surface of the second adhesive sheet. A method for manufacturing a single-sided metal-clad laminate.

2. The method for manufacturing a single-sided metal-clad laminate according to claim 1, wherein, in the lamination step, thermal lamination is performed without placing any other layers on the second main surface of the first metal foil and the second main surface of the second metal foil.

3. In the lamination process, a first surface protective film is placed on the second main surface of the first metal foil, and a second surface protective film is placed on the second main surface of the second metal foil, and then thermal lamination is performed. The method for manufacturing a single-sided metal-clad laminate according to claim 1, wherein, in the peeling step, peeling is performed not only between the first adhesive sheet and the second adhesive sheet, but also at the interface between the first metal foil and the first surface protective film, and at the interface between the second metal foil and the second surface protective film.

4. In the lamination process, the second thermoplastic resin layer of the first adhesive sheet and the second thermoplastic resin layer of the second adhesive sheet are laminated in contact with each other. A method for manufacturing a single-sided metal-clad laminate according to any one of claims 1 to 3, wherein in the peeling step, the first adhesive sheet and the second adhesive sheet are peeled apart by peeling at the interface between the second thermoplastic resin layer of the first adhesive sheet and the second thermoplastic resin layer of the second adhesive sheet.

5. In the lamination process, an intermediate protective film is placed between the first adhesive sheet and the second adhesive sheet, and the sheets are laminated such that the second thermoplastic resin layer of the first adhesive sheet and the first main surface of the intermediate protective film are in contact, and the second thermoplastic resin layer of the second adhesive sheet and the second main surface of the intermediate protective film are in contact. A method for manufacturing a single-sided metal-clad laminate according to any one of claims 1 to 3, wherein in the peeling step, peeling is performed at the interface between the second thermoplastic resin layer of the first adhesive sheet and the intermediate protective film, and at the interface between the second thermoplastic resin layer of the second adhesive sheet and the intermediate protective film, thereby peeling the first adhesive sheet and the second adhesive sheet.

6. A method for manufacturing a single-sided metal-clad laminate according to any one of claims 1 to 3, wherein the core layer of the first adhesive sheet and the core layer of the second adhesive sheet are non-thermoplastic polyimide films.

7. A method for manufacturing a single-sided metal-clad laminate according to any one of claims 1 to 3, wherein the first thermoplastic resin layer and the second thermoplastic resin layer of the first adhesive sheet, and the first thermoplastic resin layer and the second thermoplastic resin layer of the second adhesive sheet, contain a thermoplastic polyimide resin.

8. A method for manufacturing a single-sided metal-clad laminate according to any one of claims 1 to 3, wherein the first adhesive sheet and the second adhesive sheet have a tensile modulus of elasticity of 0.05 to 1.5 GPa at a temperature of 350°C.

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