Metal-clad laminate, circuit board, electronic component, and electronic device

Abstract

The present application relates to a metal-clad laminate, a circuit substrate, an electronic component, and an electronic device. A metal-clad laminate (100) includes: a first metal layer (101); and an insulating resin layer (110) laminated to the first metal layer (101), the insulating resin layer (110) having a polyimide layer (A) in contact with the first metal layer (101), and a polyimide layer (B) having a resin surface formed on a side opposite to the first metal layer (101). When a storage elastic modulus of the polyimide layer (A) at any temperature in a range from Tg+20°C to Tg+90°C is set as E'(A) with a glass transition temperature Tg of the polyimide layer (B) as a reference, and a storage elastic modulus of the polyimide layer (B) is set as E'(B), a ratio E'(A) / E'(B) of the storage elastic moduli is 2.0 or more.

Description

Technical Field

[0001] The present invention relates to a metal-clad laminate, a circuit board obtained by circuit processing thereon, electronic components and electronic devices using the circuit board. Background Technology

[0002] In recent years, with the advancements in miniaturization, weight reduction, and space-saving of electronic devices, the demand for thin, lightweight, flexible, and highly durable flexible printed circuit boards (FPCs) that withstand repeated bending has increased. FPCs can achieve three-dimensional and high-density installation even in limited spaces; therefore, their applications are gradually expanding in components such as wiring or cables and connectors for movable parts of electronic devices like hard disk drives (HDDs), digital video disks (DVDs), and smartphones.

[0003] Typically, FPCs are manufactured by etching the metal layers of metal-clad laminates, such as copper clad laminates (CCLs), to perform wiring processing. Regarding metal-clad laminates, it has been proposed to use a laminate with a high storage modulus of polyimide in the insulating resin layer in contact with the metal foil (e.g., Patent Document 1, Patent Document 2).

[0004] In single-sided metal-clad laminates, where a metal layer is included on one side of the polyimide layer serving as the insulating resin layer, thermoplastic polyimide is widely used in the polyimide layer adjacent to the metal layer. Specifically, most laminates employ a structure of thermoplastic polyimide layer / non-thermoplastic polyimide layer / thermoplastic polyimide layer starting from the metal layer side of the single-sided metal-clad laminate. When fabricating double-sided metal-clad laminates by hot-pressing a metal foil onto the outermost thermoplastic polyimide layer of this type of single-sided metal-clad laminate, hot-pressing is required at a high temperature of approximately 200°C to 400°C to ensure sufficient peel strength between the laminated surface of the outermost thermoplastic polyimide layer and the metal foil. However, if hot-pressing is performed at high temperatures, there is a problem that the thermoplastic polyimide layer on the side of the single-sided metal-clad laminate adjacent to the metal layer softens, easily causing wrinkles on the adjacent metal layer. The problem can be solved by reducing the hot-pressing temperature to suppress the softening of the thermoplastic polyimide layer. However, in this case, the adhesion between the thermoplastic polyimide layer on the laminate side and the hot-pressed metal foil becomes insufficient, and the reliability of the connection after wiring cannot be guaranteed.

[0005] [Existing Technical Documents]

[0006] [Patent Literature]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2020-104340

[0008] [Patent Document 2] Japanese Patent Application Publication No. 2006-051800 Summary of the Invention

[0009] [The problem the invention aims to solve]

[0010] The purpose of this invention is to achieve both the suppression of wrinkles and the good interfacial adhesion between the hot-pressed metal foil and the polyimide layer when metal foil is hot-pressed onto a single-sided metal-coated laminate at high temperature.

[0011] [Technical means to solve the problem]

[0012] Through diligent research, the inventors discovered that the problem can be solved by making the storage elastic modulus of the thermoplastic polyimide layer in contact with the metal layer of the single-sided metal-coated laminate greater than that of the thermoplastic polyimide layer on the laminated side, thus completing the present invention.

[0013] That is, the metal-clad laminate of the present invention includes:

[0014] First metal layer; and

[0015] An insulating resin layer is laminated onto the first metal layer, wherein...

[0016] The insulating resin layer has a polyimide layer (A) in contact with the first metal layer, and a polyimide layer (B) on the side opposite to the first metal layer, forming a resin surface.

[0017] When the storage elastic modulus of the polyimide layer (A) at any temperature in the range from Tg+20°C to Tg+90°C is set as E'(A) and the storage elastic modulus of the polyimide layer (B) is set as E'(B), the ratio of the storage elastic modulus E'(A) / E'(B) is 2.0 or higher, with the glass transition temperature Tg of the polyimide layer (B) as the reference.

[0018] In the metal-clad laminate of the present invention, the insulating resin layer may have a polyimide layer (C) stacked between the polyimide layer (A) and the polyimide layer (B).

[0019] In the metal-clad laminate of the present invention, the thickness of the first metal layer can be in the range of 6 μm to 18 μm, and the tensile elastic modulus can be in the range of 10 GPa to 100 GPa.

[0020] The metal-clad laminate of the present invention may further include a second metal layer laminated in contact with the resin surface of the polyimide layer (B).

[0021] In the metal-clad laminate of the present invention, the peel strength between the second metal layer and the polyimide layer (B) can be 0.7 kN / m or higher.

[0022] The circuit board of the present invention is formed by processing either or both of the first metal layer and the second metal layer in the metal-clad laminate.

[0023] The circuit board of the present invention is a circuit board formed by processing the first metal layer in the metal-clad laminate.

[0024] The electronic components of the present invention may include the circuit board.

[0025] The electronic device of the present invention may include the circuit board.

[0026] [The effects of the invention]

[0027] In the metal-clad laminate of the present invention, the ratio of the storage elastic modulus E'(A) of the polyimide layer (A) in contact with the first metal layer to the storage elastic modulus E'(B) of the polyimide layer (B) on the laminated side, E'(A) / E'(B), is 2.0 or higher. Therefore, even when the metal foil is hot-pressed onto the laminated side at high temperature, wrinkles in the first metal layer can be prevented. Thus, it is possible to achieve both tight interfacial adhesion between the hot-pressed metal foil and the polyimide layer and suppression of wrinkles in the first metal layer when the metal foil is hot-pressed onto the metal-clad laminate at high temperature. Therefore, by using the metal-clad laminate of the present invention as an FPC material, the reliability and yield of the circuit board can be improved. Attached Figure Description

[0028] Figure 1 This is a schematic cross-sectional view showing the structure of the metal-clad laminate according to the first embodiment of the present invention.

[0029] Figure 2 This is a schematic cross-sectional view showing the structure of the metal-clad laminate according to the second embodiment of the present invention.

[0030] Figure 3 This is an explanatory diagram illustrating a method for manufacturing a metal-clad laminate according to a second embodiment of the present invention.

[0031] Figure 4 This is an explanatory diagram illustrating a method for manufacturing a metal-clad laminate according to a third embodiment of the present invention.

[0032] Figure 5 This is a schematic cross-sectional view showing the structure of the metal-clad laminate according to the third embodiment of the present invention.

[0033] Figure 6This is an explanatory diagram illustrating a method for manufacturing a metal-clad laminate according to a fourth embodiment of the present invention.

[0034] Figure 7 This is a schematic cross-sectional view showing the structure of the metal-clad laminate according to the fourth embodiment of the present invention.

[0035] [Explanation of Symbols]

[0036] 100, 200, 300, 400: Metal-clad laminates

[0037] 101: First metal layer

[0038] 102: Second metal layer

[0039] 102A: Metal foil

[0040] 110: Insulating resin layer

[0041] 110a: Laminated surface

[0042] (A): Polyimide layer (A)

[0043] (B): Polyimide layer (B)

[0044] (C): Polyimide layer (C)

[0045] BS: Joining plate Detailed Implementation

[0046] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0047] <First Embodiment and Second Embodiment>

[0048] like Figure 1 As shown, the metal-clad laminate 100 of the first embodiment of the present invention includes a first metal layer 101 and an insulating resin layer 110 laminated on the first metal layer 101. The metal-clad laminate 100 is a single-sided metal-clad laminate.

[0049] In addition, such as Figure 2 As shown, the metal-clad laminate 200 of the second embodiment of the present invention includes a first metal layer 101, an insulating resin layer 110 laminated on the first metal layer 101, and a second metal layer 102 laminated on the insulating resin layer 110 on the side opposite to the first metal layer 101. The metal-clad laminate 200 is a double-sided metal-clad laminate.

[0050] <Insulating Resin Layer>

[0051] The insulating resin layer 110 includes a polyimide layer (A) in contact with the first metal layer 101, a polyimide layer (B) on the side opposite to the first metal layer 101 with a resin surface, and a polyimide layer (C) stacked between the polyimide layer (A) and the polyimide layer (B).

[0052] The polyimide layer (A) is a thermoplastic polyimide layer obtained by coating a polyamic acid solution onto the first metal layer 101 by casting and then drying and imidizing it, and it is a polyimide layer having a casting surface in contact with the first metal layer 101.

[0053] The polyimide layer (B) is a thermoplastic polyimide layer having a laminated surface 110a, which is used for hot-pressing metal foil, etc., as a second metal layer 102.

[0054] The polyimide layer (C) serves as the base resin layer and bears the responsibility of maintaining the mechanical strength of the insulating resin layer 110. In this invention, the polyimide layer (A) and the polyimide layer (B) forming the insulating resin layer 110 use polyimides with different storage elastic moduli.

[0055] Here, "non-thermoplastic polyimide" generally refers to polyimide that does not exhibit softening or stickiness even when heated. However, in this invention, it refers to a storage elastic modulus of 1.0 × 10⁻⁶ at 30°C, as measured using a dynamic viscoelasticity measuring device (dynamic thermomechanical analyzer, DMA). 9 The storage elastic modulus above Pa and at 320°C is shown to be 3.0 × 10⁻⁶. 8 Polyimides with a strength of Pa or higher. Furthermore, while thermoplastic polyimides generally refer to polyimides whose glass transition temperature (Tg) can be definitively determined, in this invention, they refer to polyimides with a storage modulus of elasticity of 1.0 × 10⁻⁶ at 30°C as measured using DMA. 9 The storage elastic modulus above Pa and at 320°C is shown to be less than 3.0 × 10⁻⁶. 8 Pa's polyimide.

[0056] Furthermore, without impairing the effect of the invention, the insulating resin layer 110 may include any resin layer other than the polyimide layer (A) to the polyimide layer (C).

[0057] Regarding the insulating resin layer 110, when the storage elastic modulus of the polyimide layer (A) at any temperature in the range from Tg+20°C to Tg+90°C is set as E'(A) and the storage elastic modulus of the polyimide layer (B) is set as E'(B), based on the glass transition temperature Tg of the polyimide layer (B), the ratio of the storage elastic modulus E'(A) / E'(B) is 2.0 or higher.

[0058] When a metal foil serving as the second metal layer 102 is hot-pressed onto the lamination surface 110a of the polyimide layer (B) at high temperature, the smaller the storage elastic modulus E'(B) of the polyimide layer (B), the better the filling ability of the polyimide to the micro-unevenness of the metal foil during hot pressing, and the higher the reliability of the tight bond. In addition, tension is applied during hot pressing, but the larger the storage elastic modulus E'(A) of the polyimide layer (A), the less likely the polyimide layer (A) in contact with the first metal layer 101, which serves as the support, is to soften during hot pressing at high temperature, thus suppressing the formation of wrinkles in the first metal layer 101. Therefore, by setting the ratio E'(A) / E'(B) to 2.0 or higher, when hot pressing is performed at high temperatures, such as 200°C to 400°C, particularly 270°C to 400°C, and further 320°C to 400°C, it is possible to achieve both good adhesion at the laminated surface 110a and wrinkle suppression in the first metal layer 101. From this perspective, the ratio E'(A) / E'(B) is preferably 3 to 100, more preferably 5 to 60, and most preferably 10 to 40.

[0059] In this invention, the ratio E'(A) / E'(B) only needs to satisfy the above requirement at any temperature within the range of Tg+20°C to Tg+90°C relative to the glass transition temperature Tg of the polyimide layer (B), and preferably satisfies the above requirement at all temperatures within the range of Tg+20°C to Tg+90°C. The reason for comparing the storage modulus of the polyimide layer (B) at any temperature within the range of Tg+20°C to Tg+90°C is as follows: At the glass transition temperature Tg of the polyimide layer (B), the polyimide layer (B) does not soften; therefore, Tg+20°C is set as the lower limit based on the temperature range until sufficient softening, while Tg+90°C is set as the upper limit so that a practical hot-pressing temperature can be covered even when the Tg of the polyimide layer (B) is relatively low.

[0060] The glass transition temperature Tg of the polyimide layer (A) is not particularly limited as long as the effect of the invention can be obtained, but in order to ensure the adhesion with the first metal layer 101, it is preferably in the range of 200°C or higher and 400°C or lower, more preferably in the range of 250°C or higher and 380°C or lower.

[0061] Furthermore, the storage elastic modulus E'(A) of the polyimide layer (A) is not particularly limited as long as the effects of the invention can be achieved, but a higher storage elastic modulus E'(A) is effective in suppressing wrinkles in the first metal layer 101 during hot pressing, and is preferably 1×10 7 Pa ~ 1×10 10 Within the range of Pa, more preferably 1×10 Pa8 Pa ~ 1×10 10 It is advisable to use a range within Pa.

[0062] The glass transition temperature Tg of the polyimide layer (B) is not particularly limited as long as the effect of the invention can be obtained, but in order to ensure the adhesion with the second metal layer 102, it is preferably in the range of 200°C or higher and 400°C or lower, more preferably in the range of 200°C or higher and 350°C or lower.

[0063] Furthermore, the storage elastic modulus E'(B) of the polyimide layer (B) is not particularly limited as long as the desired effect of the invention can be achieved. However, a lower storage elastic modulus E'(B) is advantageous for improving adhesion, but if it is too low, hot pressing becomes difficult. Therefore, a value of 1×10 is preferred. 5 Pa ~ 1×10 8 Within the range of Pa, more preferably 1×10 Pa 6 Pa~9×10 7 It is advisable to use a range within Pa.

[0064] In addition, the Tg and storage elastic modulus of each polyimide layer were measured using a dynamic viscoelasticity (DMA) measuring device.

[0065] Next, the resin structures of polyimide layers (A) to (C) will be described. In this invention, in order to make the ratio E'(A) / E'(B) 2.0 or higher, it is preferable to use polyimides with different compositions in the polyimide layers (A) and (B) that form the insulating resin layer 110.

[0066] Polyimide is produced by imidizing polyamic acid and contains anhydride residues and diamine residues. Here, anhydride residues refer to tetravalent groups derived from dianhydrides, and diamine residues refer to divalent groups derived from diamine compounds. When the dianhydride and diamine compound used as raw materials are reacted in approximately equimolar amounts, the types and molar ratios of dianhydride residues and diamine residues contained in the polyimide can be made to roughly correspond to the types and molar ratios of the raw materials.

[0067] Furthermore, when referred to as "polyimide" in this invention, it means, in addition to polyimide, also resins containing polymers having an imide group in their molecular structure, such as polyamide imide, polyether imide, polyester imide, polysiloxane imide, and polybenzimidazole imide.

[0068] Polyimide layer (A):

[0069] The dianhydride residues contained in the polyimide constituting the polyimide layer (A) are not particularly limited as long as the storage elastic modulus E'(A) can be controlled, but are preferably dianhydride residues derived from pyromellitic dianhydride (PMDA) (hereinafter also referred to as "PMDA residues") and / or dianhydride residues derived from 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) (hereinafter also referred to as "BTDA" residues). It is preferable that the total content of PMDA residues and / or BTDA residues is preferably in the range of 30 mol% or more, more preferably 50 mol% to 100 mol%, relative to all dianhydride residues. Both PMDA residues and BTDA residues are residues that have the effect of increasing the storage elastic modulus. Therefore, if the total amount of PMDA residues and / or BTDA residues is less than 30 mol%, the storage elastic modulus E'(A) of the polyimide layer (A) cannot be sufficiently increased, and the effect of suppressing wrinkles in the first metal layer 101 becomes insufficient.

[0070] Other acid dianhydride residues contained in the polyimide constituting the polyimide layer (A) include, for example, 4,4'-oxydiphthalic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-benzophenone tetracarboxylic acid dianhydride or 2,3,3',4'-benzophenone tetracarboxylic acid dianhydride, 2,3',3,4'-diphenyl ether tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3”,4,4”-p-terphenyltetracarboxylic acid dianhydride, 2,3,3”,4”-p-terphenyltetracarboxylic acid dianhydride or 2,2”,3,3”-p-terphenyltetracarboxylic acid dianhydride, 2,2-diphenyl ether tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3”,4,4”-p-terphenyltetracarboxylic acid dianhydride, 2,3”,3,3”-p-terphenyltetracarboxylic acid dianhydride, 2,2-diphenyl ether tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3”,4,4”-p-terphenyltetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl) ether ... (2,3-Dicarboxyphenyl)-propane dianhydride or 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride or bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)sulfone dianhydride or bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride or 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-phenanthrene-tetracarboxylic acid dianhydride, 1,2,6,7-phenanthrene-tetracarboxylic acid dianhydride or 1,2,9,10-phenanthrene-tetracarboxylic acid dianhydride, 2,3,6,7-anthracite-tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1,4,5,8-(or 2,3,6,7-)tetracarboxylic dianhydride Aromatic tetracarboxylic dianhydride residues such as 2,3,8,9-perylene-tetracarboxylic dianhydride, 3,4,9,10-perylene-tetracarboxylic dianhydride, 4,5,10,11-perylene-tetracarboxylic dianhydride or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, and 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride.

[0071] Furthermore, the diamine residues contained in the polyimide constituting the polyimide layer (A) are not particularly limited as long as the storage elastic modulus E'(A) can be controlled, but are preferably derived from diamine compounds, i.e., diamine compounds with a backbone of aromatic rings constituting the main chain linked at the para position (hereinafter also referred to as "para-linked diamine residues"). It is preferable that the total content of para-linked diamine residues is preferably in the range of 30 mol% or more, more preferably 50 mol% to 100 mol%, relative to all diamine residues. Since para-linked diamine residues have molecular linearity, they have the effect of suppressing the decrease in the storage elastic modulus E'(A) of the polyimide layer (A). Therefore, by containing para-linked diamine residues within the aforementioned range, the storage elastic modulus of the polyimide layer (A) is sufficiently increased, and the softening of the polyimide layer (A) can be suppressed even at high temperatures during hot pressing, and the formation of wrinkles in the first metal layer can be suppressed. If the content of para-linked diamine residues is less than 30 mol%, the storage elastic modulus E'(A) of the polyimide layer (A) cannot be sufficiently increased, and the effect of suppressing wrinkles in the first metal layer 101 becomes insufficient.

[0072] Representative examples of para-linked diamine residues include 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), and 2,2'-n-propyl-4,4'-diaminobiphenyl (m-POB). biphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (2,2'-divinyl-4,4'-diaminobiphenyl) Biphenyl (VAB), 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone, 1,4-bis(4-aminophenoxy)benzene (TPE-Q), 4,4'-diaminodiphenyl ether (4,4'-diaminodiphenyl) Diamine residues derived from diamine compounds such as ether (DAPE).

[0073] Of the para-linked diamine residues, from the viewpoint of balancing dimensional stability and adhesion to the first metal layer 101, diamine residues derived from 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) and 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) are particularly preferred.

[0074] Furthermore, in this specification, the hydrogen atoms in the two terminal amino groups of the "diamine compound" may be substituted, for example, to be -NR1R2 (here, R1 and R2 independently refer to any substituent such as alkyl).

[0075] Polyimide layer (B):

[0076] The dianhydride residues contained in the polyimide constituting the polyimide layer (B) are not particularly limited as long as the storage elastic modulus E'(B) can be controlled. It is preferable that the total content of PMDA residues and / or anhydride residues derived from 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) (hereinafter also referred to as "BPDA residues") is preferably in the range of 30 mol% or more, more preferably 50 mol% to 100 mol%, relative to all anhydride residues. The storage elastic modulus in the high-temperature region can be controlled by adjusting the content of BPDA residues. If the total amount of PMDA residues and / or BPDA residues is less than 30 mol%, sufficient chemical adhesion with the second metal layer 102 may not be achieved.

[0077] Other acid dianhydride residues contained in the polyimide constituting the polyimide layer (B) may be the same as those listed in the polyimide layer (A).

[0078] Furthermore, there are no particular limitations on the diamine residues contained in the polyimide constituting the polyimide layer (B), as long as the storage elastic modulus E'(B) can be controlled. It is preferable that the total content of diamine residues derived from a flexible diamine compound (hereinafter also referred to as "flexible diamine residues") is preferably 50 mol% or more, more preferably 80 mol% to 100 mol%, relative to all diamine residues. Here, a flexible diamine compound refers to a diamine compound whose aromatic ring constituting the main chain has a highly flexible linking group such as -O- or -CH2-, and more preferably includes a meta-linking group. By containing flexible diamine residues, the storage elastic modulus at temperatures above Tg can be reduced, improving the heat-pressurization and adhesion to the second metal layer 102. If the total amount of flexible diamine residues is less than 50 mol%, the storage elastic modulus of the polyimide layer (B) may become too high, reducing the heat-pressurization and adhesion to the second metal layer 102.

[0079] Preferred examples of curved diamine residues include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)dioxy]bisaniline, 4,4 '-[4-methyl-(1,3-phenylene)dioxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene)dioxy]bisaniline, 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl sulfone Phenylacetane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, (3,3'-diamino)diphenylamine, 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]aniline, 3-[3-(4-aminophenoxy)phenoxy]aniline, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]benzene The diamine residues are derived from diamine compounds such as 1,3-bis(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, bis[4,4'-(3-aminophenoxy)]benzoylaniline, 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenoxy)]bisaniline, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP). Among these, the diamine residues derived from 1,3-bis(4-aminophenoxy)benzene (TPE-R) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) exhibit excellent flexibility, thus reducing the storage elastic modulus of the polyimide layer (B) and imparting softness, making them the most preferred.

[0080] Other diamine residues contained in the polyimide constituting the polyimide layer (B) may be the same as those listed in the polyimide layer (A).

[0081] In the polyimides constituting polyimide layers (A) and (B), the coefficient of thermal expansion, storage modulus, and tensile modulus can be controlled by selecting the types of dianhydride residues and diamine residues and the molar ratio of two or more dianhydride residues or diamine residues. Furthermore, in the polyimides constituting polyimide layers (A) and (B), when multiple polyimide structural units are present, they can exist in a block form or randomly, but randomly is preferred.

[0082] Polyimide layer (C):

[0083] There are no particular restrictions on the resin structure and storage modulus of the polyimide constituting the polyimide layer (C), and known structures can be used.

[0084] In addition, in order to ensure the overall dimensional stability of the insulating resin layer 110, the coefficient of thermal expansion (CTE) of the polyimide layer (C) is preferably 30 ppm / K or less, and more preferably a low-expansion resin layer in the range of -5 ppm / K to 25 ppm / K.

[0085] The polyimides constituting polyimide layers (A) to polyimide layers (C) can be suitably formulated with other curing resin components such as plasticizers, epoxy resins, curing agents, curing accelerators, organic fillers, inorganic fillers, coupling agents, flame retardants, etc., as any component.

[0086] (Synthesis of polyimide)

[0087] Generally, polyimides can be manufactured by reacting a tetracarboxylic dianhydride with a diamine compound in a solvent, followed by heating to close the ring of the resulting polyamic acid. For example, the tetracarboxylic dianhydride and the diamine compound are dissolved in an organic solvent at approximately equimolar amounts, and the polymerization reaction is carried out by stirring at a temperature ranging from 0°C to 100°C for 30 minutes to 24 hours, thereby obtaining polyamic acid as a precursor for polyimides. During the reaction, the reactants are dissolved in the organic solvent at a concentration ranging from 5% to 30% by weight, preferably from 10% to 20% by weight. Examples of organic solvents used in polymerization reactions include: N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, cresol, etc. Two or more of these solvents may be used in combination, and aromatic hydrocarbons such as xylene and toluene may also be used. Furthermore, there are no particular limitations on the amount of this organic solvent used; it is preferable to adjust the concentration of the polyamic acid solution obtained through the polymerization reaction to approximately 5% to 30% by weight.

[0088] The synthesized polyamic acid is generally advantageously used as a reaction solvent solution, but it can be concentrated, diluted, or replaced with other organic solvents as needed. Furthermore, polyamic acid generally has excellent solvent solubility, thus it can be used advantageously. The viscosity of the polyamic acid solution is preferably in the range of 500 cP to 100,000 cP. If it deviates from this range, uneven thickness, streaks, and other defects are easily produced on the film during coating operations using a coating machine or the like. There are no particular limitations on the method of imidizing the polyamic acid; for example, heat treatment such as heating in the solvent at a temperature in the range of 80°C to 400°C for 1 hour to 24 hours is preferred.

[0089] The weight-average molecular weight of the polyamic acid, which is the precursor of the polyimides constituting polyimide layers (A) to (C), is preferably in the range of, for example, 10,000 to 400,000, and more preferably in the range of 50,000 to 350,000. If the weight-average molecular weight is less than 10,000, the strength of the insulating resin layer 110 tends to decrease and it is prone to embrittlement. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity of the polyamic acid solution becomes high, and defects such as uneven thickness and streaks are easily generated during the coating process.

[0090] <Thickness and ratio of each layer>

[0091] There is no particular limitation on the thickness of the polyimide layer (A) and the polyimide layer (B), but in order to ensure close contact with the metal foil, they are preferably 1 μm or more, and more preferably in the range of 2 μm to 10 μm.

[0092] To suppress wrinkling in the first metal layer 101 during hot pressing, the thickness of the polyimide layer (A) relative to the overall thickness of the insulating resin layer 110 is preferably in the range of 3% to 45%, more preferably in the range of 4% to 20%. When the thickness ratio is less than 3%, it is sometimes impossible to sufficiently suppress wrinkling in the first metal layer 101 during hot pressing. If the thickness ratio exceeds 45%, the proportion of low-expansion resin layer in the insulating resin layer 110 decreases, thus tending to deteriorate the dimensional stability of the insulating resin layer 110.

[0093] Furthermore, to ensure adhesion to the second metal layer 102, the thickness of the polyimide layer (B) relative to the overall thickness of the insulating resin layer 110 is preferably in the range of 3% to 45%, more preferably in the range of 4% to 20%. When the thickness ratio is less than 3%, the adhesion based on heat pressing sometimes becomes insufficient; if the thickness ratio exceeds 45%, the proportion of low-expansion resin layers within the insulating resin layer 110 decreases, thus tending to deteriorate the dimensional stability of the insulating resin layer 110.

[0094] The thickness of the polyimide layer (C) is not particularly limited and can be appropriately set according to the intended use, but is preferably in the range of 3 μm to 75 μm, and more preferably in the range of 8 μm to 50 μm. Furthermore, to ensure the dimensional stability of the insulating resin layer 110, the thickness of the polyimide layer (C) is preferably 30% or more of the total thickness of the insulating resin layer 110, and more preferably in the range of 60% to 92%.

[0095] Regarding the insulating resin layer 110, in order to reduce dielectric loss during high-frequency signal transmission, the dielectric loss tangent (Df) at 10 GHz, as measured using a split post dielectric resonator (SPDR), is preferably 0.004 or less. To improve the transmission loss of the circuit board, it is particularly important to control the dielectric loss tangent of the insulating resin layer. By keeping the dielectric loss tangent within the aforementioned range, the effect of reducing transmission loss is increased. Therefore, when the metal-clad laminate of the present invention is used as a material for circuit boards used in high-frequency applications, transmission loss can be reduced efficiently. If the dielectric loss tangent at 10 GHz exceeds 0.004, adverse conditions such as increased signal loss along the high-frequency signal transmission path are likely to occur. While there is no particular limitation on the lower limit of the dielectric loss tangent at 10 GHz, the physical properties of the insulating resin layer 110 need to be considered.

[0096] <First metal layer and second metal layer>

[0097] The metals constituting the first metal layer 101 and the second metal layer 102 are not particularly limited as long as they can be used as wiring layers in the FPC. Examples include metals selected from copper, aluminum, stainless steel, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zirconium, gold, cobalt, titanium, tantalum, zinc, lead, tin, silicon, bismuth, indium, or alloys thereof. From the viewpoint of adhesion, the first metal layer 101 and the second metal layer 102 are preferably made of metal foil. Copper foil is particularly preferred in terms of conductivity. Furthermore, in the case of continuous production of the metal-clad laminate 100 and the metal-clad laminate 200, long strips of metal foil of a specified thickness wound into a roll can be used as the metal foil.

[0098] The thickness of the first metal layer 101 is not particularly limited, but when used as an FPC material, it is preferably in the range of 6 μm to 18 μm, more preferably in the range of 9 μm to 12 μm. Similarly, the tensile modulus of elasticity of the first metal layer 101 is not particularly limited, but when used as an FPC material, it is preferably in the range of 10 GPa to 100 GPa, more preferably in the range of 15 GPa to 70 GPa. Furthermore, if the thickness and tensile modulus of elasticity of the first metal layer 101 are less than the aforementioned ranges, the mechanical strength may be insufficient and the processability may be reduced during roller-to-roll transport. On the other hand, if the thickness and tensile modulus of elasticity of the first metal layer 101 are greater than the aforementioned ranges, the processability becomes better, but on the other hand, the flexibility decreases, and previously, wrinkles were almost non-existent in the first metal layer 101 during hot pressing. However, when the thickness and tensile modulus of the first metal layer 101 are set within the range in order to balance the mechanical strength and flexibility required for use as an FPC material, wrinkles are more likely to occur during hot pressing at high temperatures. Therefore, the effects of the present invention are significantly demonstrated.

[0099] The thickness of the second metal layer 102 is not particularly limited, but when used as an FPC material, it is preferably in the range of 6 μm to 18 μm, and more preferably in the range of 9 μm to 12 μm. Furthermore, the tensile modulus of elasticity of the second metal layer 102 is not particularly limited, but when used as an FPC material, it is preferably in the range of 10 GPa to 100 GPa, and more preferably in the range of 15 GPa to 70 GPa.

[0100] <Manufacturing Method of Metal-Clad Laminates>

[0101] Examples of methods for manufacturing the metal-clad laminate 100 include:

[0102] [1] A method of coating a solution of polyamic acid onto a metal foil serving as the first metal layer 101 and then drying it before imidizing it (hereinafter referred to as the casting method);

[0103] [2] A method of coating and drying polyamic acid solution on a metal foil serving as the first metal layer 101 in a multilayer extrusion state, followed by imidization (hereinafter referred to as multilayer extrusion method).

[0104] wait.

[0105] The method described in [1] includes, for example, the following steps:

[0106] (1a) The step of coating a solution of polyamic acid onto a metal foil serving as the first metal layer 101 and drying it; and

[0107] (1b) The step of forming a polyimide layer by heat-treating polyamic acid on a metal foil to imidize it can be performed by repeatedly performing steps 1a and 1b, thereby sequentially stacking polyimide layers (A), (C), and (B) on the first metal layer 101. Alternatively, after repeatedly performing step 1a, multiple layers can be batch-imidized in step 1b.

[0108] The method described in [2] can be carried out in the same manner as the method described in [1], except that in step 1a of the method described in [1], the polyamic acid laminate structure is simultaneously coated by multilayer extrusion and dried.

[0109] In this embodiment, it is preferable to perform the imidization of polyamic acid on the first metal layer 101. Since the polyamic acid resin layer is imidized while fixed to the first metal layer 101, the stretching and shrinking of each polyimide layer during the imidization process can be suppressed, thus maintaining thickness or dimensional accuracy.

[0110] like Figure 3 As shown, the metal-clad laminate 200 can be manufactured by hot-pressing a metal foil 102A, which serves as the second metal layer 102, onto the lamination surface 110a of the insulating resin layer 110 of the metal-clad laminate 100. The temperature conditions for hot-pressing are preferably in the range of Tg+20°C to Tg+90°C relative to the glass transition temperature Tg of the polyimide layer (B).

[0111] In the metal-clad laminate 200 having the above structure, in order to ensure the reliability after being processed into a circuit board such as an FPC, the peel strength between the second metal layer 102 and the polyimide layer (B) is preferably 0.7 kN / m or more, and more preferably 1.0 kN / m or more.

[0112] <Third Implementation Method>

[0113] Reference Figure 4 and Figure 5 A third embodiment, which is an application example of the present invention, will be described. For example... Figure 4 and Figure 5 As shown, a metal-clad laminate 300 can be manufactured by arranging two metal-clad laminates 100 with the polyimide layer (B) facing each other and hot-pressing the laminated surfaces 110a together. The metal-clad laminate 300 of this embodiment is a double-sided metal-clad laminate having a structure in which a first metal layer 101 / polyimide layer (A) / polyimide layer (C) / polyimide layer (B) / polyimide layer (B) / polyimide layer (C) / polyimide layer (A) / first metal layer 101 are stacked in sequence.

[0114] <Fourth Implementation>

[0115] Reference Figure 6 and Figure 7 The fourth embodiment, which is an application example of the present invention, will be described. For example... Figure 6 and Figure 7 As shown, the metal-clad laminate 400 can be fabricated by: arranging two metal-clad laminates 100 with polyimide layers (B) facing each other, sandwiching a bonding tab BS between the two metal-clad laminates 100, and then heat-pressing the bonding tab BS to the two laminated surfaces 110a. The metal-clad laminate 400 is a double-sided metal-clad laminate having a structure consisting of a first metal layer 101 / polyimide layer (A) / polyimide layer (C) / polyimide layer (B) / bonding tab BS / polyimide layer (B) / polyimide layer (C) / polyimide layer (A) / first metal layer 101 stacked sequentially.

[0116] <Circuit Board>

[0117] The metal-clad laminates 100, 200, 300, and 400 described in the embodiments are primarily used as materials for circuit boards such as FPCs. Specifically, by patterning the first metal layer 101 and / or the second metal layer 102 of the metal-clad laminates 100, 200, 300, and 400 using conventional methods to form wiring layers, a circuit board such as an FPC, as described in one embodiment of the present invention, can be manufactured. Although figures are omitted, the circuit board of the preferred embodiment has a structure in which any one or both of the first metal layer 101 and the second metal layer 102 in the metal-clad laminates 100, 200, 300, and 400, or any one or both of the two first metal layers 101, are replaced with wiring layers.

[0118] <Electronic Components / Electronic Devices>

[0119] The electronic components and electronic devices of this embodiment include the circuit board. Examples of electronic components in this embodiment include: liquid crystal displays, organic electroluminescence (EL) displays, electronic paper, organic EL lighting, solar cells, touch screens, camera modules, inverters, converters, and their components. Examples of electronic devices include: HDDs, DVDs, mobile phones, smartphones, tablets, electronic control units (ECUs) and power control units (PCUs) in automobiles. In these electronic components or electronic devices, the circuit board is preferably used as, for example, wiring, cables, connectors, or other components for movable parts.

[0120] [Example]

[0121] The following embodiments illustrate the features of the present invention in more detail. However, the scope of the present invention is not limited to these embodiments. Furthermore, in the following embodiments, unless otherwise specified, various measurements and evaluations are based on the following.

[0122] [Viscosity Measurement]

[0123] The viscosity at 25°C was measured using an E-type viscometer (Brookfield, trade name: DV-II+Pro). The rotation speed was set to 10%–90% torque, and the viscosity was read after 2 minutes from the start of the measurement when it stabilized.

[0124] [Determination of weight-average molecular weight]

[0125] The determination was performed using a gel permeation chromatography system (Tosoh Corporation, trade name: HLC-8420GPC). Polystyrene was used as the standard, and N,N-dimethylacetamide was used as the eluent.

[0126] [Determination of Coefficient of Thermal Expansion (CTE)]

[0127] For a polyimide film measuring 3mm × 20mm, a thermomechanical analysis apparatus (manufactured by Hitachi High-Tech Science, trade name: TMA6100) was used to apply a 5.0g load while heating from 30°C to 270°C at a certain heating rate, holding at that temperature for 10 minutes, and then cooling at a rate of 5°C / min to determine the average coefficient of thermal expansion from 250°C to 100°C.

[0128] [Determination of glass transition temperature (Tg) and storage elastic modulus]

[0129] For polyimide films measuring 5 mm × 20 mm, dynamic viscoelasticity was measured using a DMA (TA Instruments, trade name: RSA3) device at a heating rate of 5 °C / min from 30 °C to 400 °C and a frequency of 1 Hz. The glass transition temperature was determined based on the maximum temperature of tanδ of the main dispersion.

[0130] [Determination of peel strength]

[0131] A single-sided copper-clad laminate is obtained by etching away the copper foil (first copper foil layer) on the coated side of the flexible copper-clad laminate. The copper foil (second copper foil layer) of the single-sided copper-clad laminate is then processed with circuitry to a width of 1.0 mm to prepare a sample. The surface of the polyimide layer is fixed to an aluminum plate using double-sided tape, and the results are measured using a Tensilon testing machine (manufactured by Toyo Seiki Co., Ltd., trade name: Strograph VE-1D). The copper foil is stretched in a 180-degree direction at a speed of 50 mm / min, and the center strength after peeling 10 mm is determined. A peel strength of 1.3 kN / m or more is marked as "◎", a peel strength of 1.0 kN / m or more but less than 1.3 kN / m is marked as "○", a peel strength of 0.7 kN / m or more but less than 1.0 kN / m is marked as "△", and a peel strength less than 0.7 kN / m is marked as "×".

[0132] [Evaluation of appearance and shape]

[0133] The appearance of the copper foil (first copper foil layer) on the coated side of the flexible copper-clad laminate was evaluated. A 350mm × 250mm sheet was cut from the laminated sample and visually inspected. A "◎" was used to indicate a good shape without wrinkles; "○" was used to indicate localized horizontal wrinkles that did not affect circuit fabrication; "△" was used to indicate horizontal wrinkles that did not affect circuit fabrication across the entire surface; and "×" was used to indicate horizontal wrinkles that affected circuit fabrication across the entire surface.

[0134] [Determination of tensile modulus of elasticity]

[0135] After cutting copper foil to a width of 12.7 mm, it was annealed at 380°C for 15 minutes, and then tested using a tensile compression testing machine (manufactured by Toyo Seiki Co., Ltd., trade name: Strograph R-1). Tensile testing was performed at a clamping distance of 101.6 mm and a scanning speed of 10 mm / min, and the tensile modulus of elasticity was calculated based on the slope of the obtained stress-displacement curve at 0.2% displacement.

[0136] [Determination of dielectric loss tangent]

[0137] The dielectric loss tangent of a polyimide film at a frequency of 10 GHz was measured using a vector network analyzer (Agilent Technologies, trade name: E8363C) and a split-pillar dielectric resonator (SPDR resonator). Furthermore, the material used in the measurement was a polyimide film prepared by etching away the copper foil layer of a flexible copper-clad laminate, which was then placed at a temperature of 24°C–26°C and a humidity of 45%–55% for 24 hours.

[0138] The codes used in the examples and comparative examples denote the following compounds.

[0139] PMDA: Pyromellitic dianhydride

[0140] BTDA: 3,3',4,4'-benzophenone tetracarboxylic dianhydride

[0141] BPDA: 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride

[0142] m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

[0143] TPE-R: 1,3-Bis(4-aminophenoxy)benzene

[0144] BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

[0145] DMAc: N,N-dimethylacetamide

[0146] Copper Foil 1: Rolled copper foil, 9 μm thick, tensile modulus of elasticity after annealing 36 GPa

[0147] Copper foil 2: Rolled copper foil, 12 μm thick, with a tensile modulus of elasticity of 36 GPa after annealing.

[0148] Copper foil 3: Rolled copper foil, 18 μm thick, with a tensile modulus of elasticity of 36 GPa after annealing.

[0149] Copper foil 4: Rolled copper foil, 18 μm thick, with a tensile modulus of elasticity of 18 GPa after annealing.

[0150] (Synthesis example 1)

[0151] 21.43 parts by weight of m-TB (100.92 mol parts) were added to 255.0 parts by weight of DMAc, and the mixture was stirred at room temperature for at least 30 minutes until completely dissolved. Then, 16.26 parts by weight of PMDA (74.56 mol parts) and 7.31 parts by weight of BPDA (24.85 mol parts) were added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution 1 with a viscosity of 27,400 cP and a weight average molecular weight of 117,000.

[0152] A polyamic acid solution 1 is uniformly coated onto a substrate to a hardened thickness of approximately 25 μm, followed by heating and drying at below 140°C to remove the solvent. Then, heat treatment is performed by progressively increasing the temperature from 140°C to 360°C to complete imidization, thereby preparing a polyimide film 1 as shown. The obtained polyimide film 1 has a CTE of 23 ppm / K and is non-thermoplastic.

[0153] (Synthesis example 2)

[0154] 10.55 parts by weight of TPE-R (36.10 mol) and 7.66 parts by weight of m-TB (33.10 mol) were added to 264.0 parts by weight of DMAc, and the mixture was stirred at room temperature for at least 30 minutes until completely dissolved. Then, 10.89 parts by weight of PMDA (49.93 mol) and 6.90 parts by weight of BTDA (21.40 mol) were added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution 2 with a viscosity of 3,800 cP and a weight average molecular weight of 180,000.

[0155] The polyimide film 2, prepared in the same manner as in Synthesis Example 1, has a Tg of 300°C and a storage elastic modulus of 1.2 × 10⁻⁶. 9 Pa (270℃), 1.2×10 9 Pa (275℃), 2.0×10 8 Pa (350℃) and 1.3×10 8 Pa (400℃).

[0156] (Synthesis example 3)

[0157] Add 23.20 parts by weight of BAPP (56.53 mol) to 264.0 parts by weight of DMAc, and stir at room temperature for at least 30 minutes until completely dissolved. Then, add 11.95 parts by weight of PMDA (54.77 mol) and 0.85 parts by weight of BPDA (2.88 mol), and stir at room temperature for 4 hours to obtain a polyamic acid solution 3 with a viscosity of 1,700 cP and a weight average molecular weight of 200,000.

[0158] The polyimide film 3, prepared in the same manner as in Synthesis Example 1, has a Tg of 320°C and a storage modulus of 1.5 × 10⁻⁶. 9 Pa (270℃), 1.0×10 8 Pa (275℃), 6.3×10 7 Pa (350℃) and 1.9×10 7 Pa (400℃).

[0159] (Synthesis Example 4)

[0160] 17.94 parts by weight of TPE-R (61.36 mol) and 0.69 parts by weight of m-TB (3.23 mol) were added to 264.0 parts by weight of DMAc, and the mixture was stirred at room temperature for at least 30 minutes until completely dissolved. Then, 11.63 parts by weight of BPDA (39.53 mol) and 5.75 parts by weight of PMDA (26.35 mol) were added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution 4 with a viscosity of 2,500 cP and a weight average molecular weight of 121,000.

[0161] The polyimide film 4, prepared in the same manner as in Synthesis Example 1, has a Tg of 225°C and a storage modulus of 1.0 × 10⁻⁶. 8 Pa (275℃).

[0162] (Synthesis Example 5)

[0163] Add 15.33 parts by weight of TPE-R (52.43 mol) and 2.78 parts by weight of m-TB (13.11 mol) to 264.0 parts by weight of DMAc, and stir at room temperature for at least 30 minutes until completely dissolved. Then add 12.79 parts by weight of BPDA (43.45 mol) and 5.10 parts by weight of PMDA (23.40 mol), and stir at room temperature for 4 hours to obtain a polyamic acid solution with a viscosity of 2,300 cP and a weight average molecular weight of 118,000.

[0164] The polyimide film 5, prepared in the same manner as in Synthesis Example 1, has a Tg of 220°C and a storage modulus of 4.4 × 10⁻⁶. 7 Pa (270℃).

[0165] [Example 1]

[0166] Polyamic acid solution 2 is coated onto copper foil 1 to a hardened thickness of 2 μm, then dried by heating at below 140°C and the solvent is removed. Polyamic acid solution 1 is then coated onto it to a hardened thickness of 21 μm, then dried by heating at below 140°C and the solvent is removed. Next, polyamic acid solution 3 is coated onto it to a hardened thickness of 2 μm, then dried by heating at below 140°C and the solvent is removed. Then, imidization is performed by gradually increasing the temperature from 140°C to 360°C to prepare a single-sided copper-clad laminate 1. Copper foil 2 is placed on the polyimide layer side of the obtained single-sided copper-clad laminate 1, and a hot roller laminator is used at a lamination pressure of 1 kN / cm². 2 Flexible copper-clad laminate 1 was obtained by continuous hot lamination at a lamination temperature of 350℃. The evaluation results of flexible copper-clad laminate 1 are shown in Table 1.

[0167] [Example 2]

[0168] Except that copper foil 2 is used instead of copper foil 1, the same procedure as in Example 1 is followed to obtain the flexible copper clad laminate 2. The evaluation results of the flexible copper clad laminate 2 are shown in Table 1.

[0169] [Example 3]

[0170] Except that copper foil 3 is used instead of copper foil 1, the same procedure as in Example 1 is followed to obtain the flexible copper clad laminate 3. The evaluation results of the flexible copper clad laminate 3 are shown in Table 1.

[0171] [Example 4]

[0172] Except that copper foil 4 is used instead of copper foil 1, the same procedure as in Example 1 is followed to obtain the flexible copper clad laminate 4. The evaluation results of the flexible copper clad laminate 4 are shown in Table 1.

[0173] [Example 5]

[0174] Except that copper foil 3 was used instead of copper foil 1 and the lamination temperature was set to 400°C, the flexible copper-clad laminate 5 was obtained in the same manner as in Example 1. The evaluation results of the flexible copper-clad laminate 5 are shown in Table 1.

[0175] [Example 6]

[0176] Except for using copper foil 2 instead of copper foil 1, using polyamic acid solution 4 instead of polyamic acid solution 3, and setting the lamination temperature to 275°C, the flexible copper-clad laminate 6 was obtained in the same manner as in Example 1. The evaluation results of the flexible copper-clad laminate 6 are shown in Table 1.

[0177] [Example 7]

[0178] Except for using copper foil 2 instead of copper foil 1, using polyamic acid solution 5 instead of polyamic acid solution 3, and setting the lamination temperature to 270°C, the flexible copper-clad laminate 7 was obtained in the same manner as in Example 1. The evaluation results of the flexible copper-clad laminate 7 are shown in Table 1.

[0179] [Example 8]

[0180] Except for using copper foil 2 instead of copper foil 1, using polyamic acid solution 3 instead of polyamic acid solution 2, using polyamic acid solution 5 instead of polyamic acid solution 3, and setting the lamination temperature to 270°C, the flexible copper-clad laminate 8 was obtained in the same manner as in Example 1. The evaluation results of the flexible copper-clad laminate 8 are shown in Table 1.

[0181] Comparative Example 1

[0182] Except that copper foil 2 is used instead of copper foil 1 and polyamic acid solution 2 is used instead of polyamic acid solution 3, the same procedure as in Example 1 was followed to obtain the flexible copper clad laminate 9. The evaluation results of the flexible copper clad laminate 9 are shown in Table 1.

[0183] Comparative Example 2

[0184] Except for using copper foil 2 instead of copper foil 1, using polyamic acid solution 5 instead of polyamic acid solution 2, using polyamic acid solution 5 instead of polyamic acid solution 3, and setting the lamination temperature to 270°C, the flexible copper-clad laminate 10 was obtained in the same manner as in Example 1. The evaluation results of the flexible copper-clad laminate 10 are shown in Table 1.

[0185] In addition, "Layer (A)" and "Layer (B)" in Table 1 refer to "Polyimide Layer (A)" and "Polyimide Layer (B)" respectively. Furthermore, E'(A) and E'(B) in Table 1 both refer to the storage elastic modulus at the lamination temperature.

[0186] [Table 1]

[0187]

[0188] The dielectric loss tangent (Df) of polyimide films 1 to 10 prepared by etching away the copper foil layers of flexible copper clad laminates 1 to 8 and comparative examples 1 to 2 is shown in Table 2 at a frequency of 10 GHz.

[0189] [Table 2]

[0190]

[0191] The embodiments of the present invention have been described in detail above for illustrative purposes, but the present invention is not limited to the described embodiments and can be modified in various ways.

Claims

1. A metal-clad laminate, comprising: First metal layer; as well as An insulating resin layer is laminated onto the first metal layer, and the metal-clad laminate is characterized in that... The insulating resin layer has a polyimide layer (A) in contact with the first metal layer, and a polyimide layer (B) on the side opposite to the first metal layer, forming a resin surface. When the storage modulus of the polyimide layer (A) at any temperature in the range from Tg+20°C to Tg+90°C is set as E'(A) and the storage modulus of the polyimide layer (B) is set as E'(B), the ratio of the storage modulus E'(A) / E'(B) is 2.0 or higher.

2. The metal-clad laminate according to claim 1, wherein, The insulating resin layer has a polyimide layer (C) stacked between the polyimide layer (A) and the polyimide layer (B).

3. The metal-clad laminate according to claim 1 or 2, wherein, The thickness of the first metal layer is in the range of 6μm to 18μm, and the tensile elastic modulus is in the range of 10GPa to 100GPa.

4. The metal-clad laminate according to claim 1 further comprises a second metal layer laminated in contact with the resin surface of the polyimide layer (B).

5. The metal-clad laminate according to claim 4, wherein, The peel strength between the second metal layer and the polyimide layer (B) is greater than 0.7 kN / m.

6. A circuit board, formed by processing either or both of the first metal layer and the second metal layer in the metal-clad laminate according to claim 4.

7. A circuit board, formed by processing the first metal layer in the metal-clad laminate as described in claim 1.

8. An electronic component, characterized in that, Includes the circuit board as described in claim 6 or 7.

9. An electronic device, characterized in that, Includes the circuit board as described in claim 6 or 7.

Images