JP2022126664A - Metal-clad laminate and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal-clad laminate and a circuit board which each have an adhesive layer that is excellent in adhesion, are small in a dielectric constant and a dielectric loss tangent, and can reduce transmission loss even in high frequency transmission.

SOLUTION: A metal-clad laminate has: an insulating resin layer; an adhesive layer laminated on at least one surface of the insulating resin layer; and a metal layer laminated on the insulating resin layer through the adhesive layer. The metal layer is made of a copper foil, and has a corrosion prevention treatment layer which is formed through corrosion prevention treatment and contains a plating treatment layer containing zinc and a chromated layer on a surface contacting the adhesive layer in the copper foil. In the corrosion prevention treatment layer, a nickel content is 0.01 mg/dm² or less, a cobalt content falls within a range of 0.01-0.5 mg/dm², a molybdenum content falls within a range of 0.01-0.5 mg/dm², and the total amount (Co+Mo) of the cobalt element and the molybdenum content falls within a range of 0.1-0.7 mg/dm². The adhesive layer has polyimide containing a tetracarboxylic acid residue and a diamine residue, and contains 50 pts.mol of a diamine residue derived from dimer acid type diamine obtained by substituting a primary aminomethyl group or an amino group for two terminal carboxylic acid groups of a dimer acid with respect to 100 pts.mol of a diamine residue.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a metal-clad laminate, an adhesive sheet, an adhesive polyimide resin composition, and a circuit board.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, flexible printed circuit boards (FPCs) that are thin, lightweight, flexible, and have excellent durability even after repeated bending have been developed. Circuits are in increasing demand. Since FPCs can be mounted three-dimensionally and at high density even in a limited space, their applications are expanding, for example, to the wiring of moving parts of electronic devices such as HDDs, DVDs, and smartphones, as well as components such as cables and connectors. I'm doing it.

In addition to the higher density described above, the performance of equipment has advanced, so it is also necessary to deal with higher frequency transmission signals. 2. Description of the Related Art When transmitting a high-frequency signal, if the transmission loss in the transmission path is large, problems such as the loss of the electrical signal and the increase in signal delay time occur. Therefore, reduction of transmission loss will be important for FPC in the future. In order to cope with higher frequencies, FPCs having dielectric layers made of liquid crystal polymers, which are characterized by low dielectric constant and low dielectric loss tangent, are used. However, although liquid crystal polymers are excellent in dielectric properties, there is room for improvement in heat resistance and adhesiveness to metal layers.

A metal-clad laminate, which is a material for circuit boards such as FPC, has a form in which a metal layer to be wired and an insulating resin layer are bonded via an adhesive layer made of an adhesive resin (three-layer metal-clad laminate ) is known (for example, Patent Document 1). In order to use such a three-layer metal-clad laminate as a circuit board for high-frequency signal transmission, it is considered important to improve the dielectric properties of the adhesive layer.

By the way, as a technology related to an adhesive layer having polyimide as a main component, there are polyimides made from diamine compounds derived from aliphatic diamines such as dimer acid, and amino compounds having at least two primary amino groups as functional groups. is applied to an adhesive layer of a coverlay film (for example, Patent Document 2). The crosslinked polyimide resin of Patent Document 2 does not generate a volatile component composed of a cyclic siloxane compound, has excellent soldering heat resistance, and maintains the adhesive strength between the wiring layer and the coverlay film even in an environment where it is repeatedly exposed to high temperatures. It has the advantage of not deteriorating. However, Patent Literature 2 does not discuss applicability to high-frequency signal transmission or application to adhesive layers in three-layer metal-clad laminates.

International publication WO2016/031960 Japanese Patent No. 5777944

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal-clad laminate and a circuit board provided with an adhesive layer that has excellent adhesiveness, a small dielectric constant and a small dielectric loss tangent, and is capable of reducing transmission loss even in high-frequency transmission.

As a result of intensive research, the present inventors have found that polyimide is used for the adhesive layer that functions to bond the wiring layer and the insulating resin layer in the circuit board, and the type and amount of the monomer that is the raw material of the polyimide is controlled. The present inventors have found that it is possible to achieve a low dielectric constant and a low dielectric loss tangent while maintaining excellent adhesiveness, thereby completing the present invention.

The metal-clad laminate of the present invention comprises an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer. have.
The adhesive layer in the metal-clad laminate of the present invention has a polyimide containing a tetracarboxylic acid residue and a diamine residue.
And the polyimide, with respect to 100 mole parts of the diamine residue,
It is characterized by containing 50 mol parts or more of a diamine residue derived from a dimer acid-type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

In the metal-clad laminate of the present invention, the polyimide is a tetracarboxylic anhydride represented by the following general formulas (1) and/or (2) with respect to 100 mol parts of the tetracarboxylic acid residue. A total of 90 mol parts or more of induced tetracarboxylic acid residues may be contained.

In general formula (1), X represents a single bond or a divalent group selected from the following formula, and in general formula (2), the cyclic portion represented by Y is a 4-membered ring, a 5-membered ring , represents that a saturated cyclic hydrocarbon group selected from a 6-, 7-, or 8-membered ring is formed.

In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, where n is 1 Indicates an integer from ~20.

In the metal-clad laminate of the present invention, the polyimide is
It may contain a diamine residue derived from the dimer acid-type diamine in the range of 50 mol parts or more and 99 mol parts or less,
containing a diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the following general formulas (B1) to (B7) in the range of 1 to 50 mol parts; good too.

In formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group, and the linking group A independently represents -O-, -S-, -CO- , —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C(CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently Indicates an integer from 0 to 4. However, the formula (B3) that overlaps with the formula (B2) is excluded, and the formula (B5) that overlaps with the formula (B4) is excluded.

In the metal-clad laminate of the present invention, the metal layer may be made of copper foil, and the surface of the copper foil in contact with the adhesive layer may be subjected to antirust treatment.

The circuit board of the present invention is obtained by processing the metal layer of any one of the above metal-clad laminates into wiring.

The adhesive sheet of the present invention is a metal having an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer. An adhesive sheet for forming the adhesive layer in a tension laminate.
The adhesive sheet of the present invention has polyimide containing tetracarboxylic acid residues and diamine residues.
And the polyimide, with respect to 100 mole parts of the diamine residue,
It is characterized by containing 50 mol parts or more of a diamine residue derived from a dimer acid-type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

In the adhesive sheet of the present invention, the polyimide is derived from a tetracarboxylic anhydride represented by the general formula (1) and/or (2) with respect to 100 mol parts of the tetracarboxylic acid residue. may contain 90 mole parts or more of tetracarboxylic acid residues in total.

In the adhesive sheet of the present invention, the polyimide is
It may contain a diamine residue derived from the dimer acid-type diamine in the range of 50 mol parts or more and 99 mol parts or less,
containing a diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the general formulas (B1) to (B7) in the range of 1 mol part or more and 50 mol parts or less; good too.

The adhesive polyimide resin composition of the present invention comprises an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer. A composition for forming the adhesive layer in a metal-clad laminate having
The adhesive polyimide resin composition of the present invention contains a polyimide containing a tetracarboxylic acid residue and a diamine residue.
And the polyimide, with respect to 100 mole parts of the diamine residue,
It is characterized by containing 50 mol parts or more of a diamine residue derived from a dimer acid-type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

In the adhesive polyimide resin composition of the present invention, the polyimide is a tetracarboxylic anhydride represented by the above general formula (1) and / or (2) with respect to 100 mol parts of the tetracarboxylic acid residue. It may contain 90 mol parts or more of tetracarboxylic acid residues derived from substances in total.

In the adhesive polyimide resin composition of the present invention, the polyimide is
It may contain a diamine residue derived from the dimer acid-type diamine in the range of 50 mol parts or more and 99 mol parts or less,
containing a diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the general formulas (B1) to (B7) in the range of 1 mol part or more and 50 mol parts or less; good too.

In the metal-clad laminate of the present invention, by forming the adhesive layer with a polyimide into which specific tetracarboxylic acid residues and diamine residues are introduced, it is possible to secure adhesiveness and achieve a low dielectric constant and a low dielectric loss tangent. did. By using the metal-clad laminate of the present invention, it can be applied to circuit boards and the like that transmit high-frequency signals of 10 GHz or more, for example. Therefore, it is possible to improve the reliability and yield of the circuit board.

An embodiment of the present invention will be described in detail.

[Metal clad laminate]
The metal-clad laminate of the present embodiment comprises an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer. It is a so-called three-layer metal-clad laminate. In the three-layer metal-clad laminate, the adhesive layer may be provided on one or both sides of the insulating resin layer, and the metal layer may be provided on one or both sides of the insulating resin layer via the adhesive layer. . That is, the metal-clad laminate of the present embodiment may be a single-sided metal-clad laminate or a double-sided metal-clad laminate. A single-sided FPC or a double-sided FPC can be manufactured by etching the metal layer of the metal-clad laminate of the present embodiment for wiring circuit processing.

<Insulating resin layer>
The insulating resin layer is not particularly limited as long as it is made of an electrically insulating resin, and examples thereof include polyimide, epoxy resin, phenol resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, and ETFE. can be made, but is preferably made of polyimide. The polyimide layer constituting the insulating resin layer may be a single layer or multiple layers, but preferably includes a non-thermoplastic polyimide layer. Here, the term "non-thermoplastic polyimide" generally refers to a polyimide that does not soften or exhibit adhesiveness when heated. A polyimide having a storage modulus of 1.0×10 ⁹ Pa or more at 30° C. and a storage modulus of 3.0×10 ⁸ Pa or more at 300° C.

Polyimide is produced by imidizing a precursor polyamic acid obtained by reacting a specific acid anhydride and a diamine compound. Examples are understood (as is the thermoplastic polyimide that forms the adhesive layer described below). The polyimide used in the present invention includes so-called polyimides as well as those having imide groups in their structures, such as polyamideimides, polybenzimidazoles, polyimide esters, polyetherimides, and polysiloxaneimides.

(acid anhydride)
Acid anhydrides used in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer include, for example, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 1 ,4-phenylenebis(trimellitic acid monoester) dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-, 2,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride anhydride, 2,3′,3,4′-diphenyl ether tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3″,4,4″-, 2 ,3,3'',4''- or 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,2-bis(2,3- or 3,4- dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3.4-dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10- phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic 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-naphthalene Tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- 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, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- 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, 2, 2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, p-phenylene bis(trimellitic acid monoester acid anhydride) products), and acid dianhydrides such as ethylene glycol bis-anhydro-trimellitate.

(Diamine compound)
Examples of the diamine compound used in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer include aromatic diamine compounds and aliphatic diamine compounds. Specific examples thereof include 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB), 2,2′-n- Propyl-4,4'-diaminobiphenyl (m-NPB), 4-aminophenyl-4'-aminobenzoate (APAB), 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[ 4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)phenyl]methane , bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)]benzophenone, 9,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 2,2- Bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'- diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl) ether, bis(p-β -methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2 ,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m -xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4, 4'-diaminobenzanilide, 4,4'-dia Minobenzanilide, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 6-amino-2-(4-aminophenoxy)benzoxazole, 1,3-bis(3-aminophenoxy ) Diamine compounds such as benzene and dimer acid-type diamines in which the two terminal carboxylic acid groups of dimer acid are substituted with primary aminomethyl groups or amino groups.

In the non-thermoplastic polyimide, by selecting the types of the acid anhydrides and diamine compounds, and the respective molar ratios when two or more acid anhydrides and diamine compounds are applied, the thermal expansion coefficient, storage modulus, Tensile modulus and the like can be controlled. Further, in the non-thermoplastic polyimide, when it has a plurality of polyimide structural units, it may exist as a block or may exist randomly, but from the viewpoint of suppressing in-plane variation, it is possible to exist randomly. preferable.

The thickness of the insulating resin layer is, for example, preferably in the range of 1 to 125 μm, more preferably in the range of 5 to 50 μm. If the thickness of the insulating resin layer is less than the above lower limit, problems such as insufficient electrical insulation may occur. On the other hand, if the thickness of the insulating resin layer exceeds the above upper limit, problems such as warping of the metal-clad laminate will occur. Also, the ratio of the thickness of the insulating resin layer to the thickness of the adhesive layer (thickness of the insulating resin layer/thickness of the adhesive layer) is preferably in the range of 0.5 to 2.0. Warping of the metal-clad laminate can be suppressed by using such a ratio.

The non-thermoplastic polyimide layer constituting the insulating resin layer has low thermal expansion and has a coefficient of thermal expansion (CTE) of preferably 10 ppm/K or more and 30 ppm/K or less, more preferably 10 ppm/K or more and 25 ppm/K or less. is within the range of If the CTE is less than 10 ppm/K or more than 30 ppm/K, warping will occur and dimensional stability will decrease. A polyimide layer having a desired CTE can be obtained by appropriately changing the combination of raw materials to be used, thickness, and drying/curing conditions.

For example, when the insulating resin layer is applied to a circuit board, the dielectric loss tangent (Tan δ) at 10 GHz is 0.02 or less, more preferably 0.0005 or more and 0.01 or less, in order to suppress deterioration of dielectric loss. Within the range, more preferably within the range of 0.001 to 0.008. If the dielectric loss tangent of the insulating resin layer at 10 GHz exceeds 0.02, problems such as loss of electrical signals on the transmission path of high-frequency signals tend to occur when used in circuit boards such as FPCs. On the other hand, although the lower limit value of the dielectric loss tangent of the insulating resin layer at 10 GHz is not particularly limited, the control of physical properties as the insulating resin layer of the circuit board is taken into consideration.

For example, when the insulating resin layer is applied as an insulating layer of a circuit board, the insulating layer as a whole preferably has a dielectric constant of 4.0 or less at 10 GHz in order to ensure impedance matching. If the dielectric constant of the insulating resin layer exceeds 4.0 at 10 GHz, it leads to deterioration of the dielectric loss of the insulating resin layer when used for a circuit board such as FPC, resulting in loss of electrical signals on the transmission path of high frequency signals. inconvenience is more likely to occur.

The insulating resin layer may contain a filler if necessary. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, metal salts of organic phosphinic acids, and the like. These can be used singly or in combination of two or more.

<Adhesive layer>
The adhesive layer contains a polyimide containing a tetracarboxylic acid residue derived from a tetracarboxylic anhydride and a diamine residue derived from a diamine compound, and is preferably made of a thermoplastic polyimide. Here, the term "thermoplastic polyimide" generally refers to a polyimide whose glass transition temperature (Tg) can be clearly identified. A polyimide having a storage modulus of 0×10 ⁸ Pa or more and a storage modulus of less than 3.0×10 ⁷ Pa at 300° C. In the present invention, the tetracarboxylic acid residue means a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue is a divalent group derived from a diamine compound. means that

(tetracarboxylic acid residue)
The thermoplastic polyimide forming the adhesive layer is derived from a tetracarboxylic anhydride represented by the following general formulas (1) and/or (2) with respect to 100 mol parts of the tetracarboxylic acid residue. tetracarboxylic acid residue (hereinafter sometimes referred to as "tetracarboxylic acid residue (1) and "tetracarboxylic acid residue (2)") is preferably contained in a total of 90 mol parts or more. In the present invention, the tetracarboxylic acid residues (1) and/or (2) are contained in a total of 90 mol parts or more with respect to 100 mol parts of the tetracarboxylic acid residues, thereby forming an adhesive layer. While imparting solvent solubility to the polyimide, it is easy to achieve both flexibility and heat resistance of the thermoplastic polyimide, which is preferable. If the total amount of tetracarboxylic acid residues (1) and/or (2) is less than 90 mol parts, the solvent solubility of the thermoplastic polyimide tends to decrease.

In general formula (1), X represents a single bond or a divalent group selected from the following formula, and in general formula (2), the cyclic portion represented by Y is a 4-membered ring, a 5-membered ring , a cyclic saturated hydrocarbon group selected from a 6-, 7-, or 8-membered ring.

In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, where n is 1 Indicates an integer from ~20.

Tetracarboxylic dianhydrides for deriving the tetracarboxylic acid residue (1) include, for example, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′, 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride (ODPA), 4, 4′-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), p-phenylenebis(tri mellitic acid monoester acid anhydride).

Further, the tetracarboxylic dianhydride for deriving the tetracarboxylic acid residue (2) includes, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4- Cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,4,5-cycloheptanetetracarboxylic dianhydride, 1,2,5,6- cyclooctanetetracarboxylic dianhydride, and the like.

The thermoplastic polyimide forming the adhesive layer is a tetracarboxylic acid derived from an acid anhydride other than the tetracarboxylic acid anhydride represented by the above general formula (1) or (2) within the range that does not impair the effects of the invention. It can contain residues. Acid anhydride residues other than the tetracarboxylic acid residue (1) or (2) are exemplified as the acid anhydrides used in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer in the insulating resin layer described above. can be mentioned.

(diamine residue)
The thermoplastic polyimide forming the adhesive layer contains 50 mol parts or more, for example, 50 mol parts or more and 99 mol parts or less of the dimer acid-type diamine residue derived from the dimer acid-type diamine with respect to 100 mol parts of the diamine residue. , preferably 80 mol parts or more, for example, 80 mol parts or more and 99 mol parts or less. By containing the dimer acid-type diamine residue in the amount described above, it is possible to improve the dielectric properties of the adhesive layer and ensure the necessary flexibility of the adhesive layer. If the dimer acid-type diamine residue is less than 50 mol parts with respect to 100 mol parts of the diamine residue, sufficient adhesiveness as an adhesive layer interposed between the insulating resin layer and the metal layer cannot be obtained. Also, the metal-clad laminate may warp.

Here, the dimer acid-type diamine means that the two terminal carboxylic acid groups (-COOH) of the dimer acid are substituted with primary aminomethyl groups (-CH ₂ -NH ₂ ) or amino groups (-NH ₂ ). means a diamine consisting of Dimer acid is a known dibasic acid obtained by an intermolecular polymerization reaction of unsaturated fatty acids, and its industrial production process is almost standardized in the industry. It is obtained by dimerization with Etc. Industrially obtained dimer acid is mainly composed of dibasic acid with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms such as oleic acid and linoleic acid. , any amount of monomeric acids (18 carbon atoms), trimer acids (54 carbon atoms), and other polymerized fatty acids of 20 to 54 carbon atoms. In the present invention, it is preferable to use dimer acid whose content is increased to 90% by weight or more by molecular distillation. Moreover, although a double bond remains after the dimerization reaction, in the present invention, the dimer acid includes the one which is further hydrogenated to reduce the degree of unsaturation.

As a feature of the dimer acid-type diamine, it is possible to impart properties derived from the skeleton of the dimer acid to the polyimide. That is, the dimer acid-type diamine is a macromolecular aliphatic with a molecular weight of about 560 to 620, so that the molar volume of the molecule can be increased and the polar groups of the polyimide can be relatively reduced. Such features of the dimer acid-type diamine are considered to contribute to improving the dielectric properties by reducing the dielectric constant and the dielectric loss tangent while suppressing the deterioration of the heat resistance of the polyimide. In addition, since it has two freely moving hydrophobic chains having 7 to 9 carbon atoms and two chain aliphatic amino groups having a length close to 18 carbon atoms, it not only gives the polyimide flexibility, Since polyimide can have an asymmetrical chemical structure or a non-planar chemical structure, it is thought that a low dielectric constant and a low dielectric loss tangent of polyimide can be achieved.

Dimer acid-type diamines are commercially available, for example, PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name) and PRIAMINE 1075 (trade name) manufactured by Croda Japan, Versamin 551 (trade name) manufactured by Cognis Japan. ), Versamin 552 (trade name), and the like.

In addition, the thermoplastic polyimide forming the adhesive layer contains a diamine residue derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7). It is preferably contained within the range of 1 mol part or more and 50 mol parts or less in total, and more preferably contained within the range of 1 mol part or more and 20 mol parts or less with respect to 100 mol parts. Since the diamine compounds represented by the general formulas (B1) to (B7) have a flexible molecular structure, by using at least one diamine compound selected from these in an amount within the above range, the polyimide molecule It can improve chain flexibility and impart thermoplasticity. When the total amount of diamine (B1) to diamine (B7) exceeds 50 mol parts per 100 mol parts of the total diamine component, the solvent solubility of the polyimide may be low. The flexibility of the steel may be insufficient, and the workability at high temperatures may deteriorate.

In formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group, and the linking group A independently represents -O-, -S-, -CO- , —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C(CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently Indicates an integer from 0 to 4. However, the formula (B3) that overlaps with the formula (B2) is excluded, and the formula (B5) that overlaps with the formula (B4) is excluded.
In formulas (B1) to (B7), the hydrogen atoms in the two terminal amino groups may be substituted, for example —NR ₂ R ₃ (wherein R ₂ and R ₃ are independently alkyl (meaning any substituent such as a group).

The diamine represented by formula (B1) (hereinafter sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. In this diamine (B1), the amino group directly attached to at least one benzene ring and the divalent linking group A are at the meta position, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B1) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -CO-, -SO ₂ -, -S-, or -COO-.

Diamine (B1) includes, for example, 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'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, (3,3'-bisamino ) diphenylamine and the like.

The diamine represented by formula (B2) (hereinafter sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. This diamine (B2) has an amino group directly attached to at least one benzene ring and a divalent linking group A at the meta position, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B2) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B2) include 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzenamine, 3-[3-(4-aminophenoxy)phenoxy] Benzenamine and the like can be mentioned.

The diamine represented by formula (B3) (hereinafter sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. This diamine (B3) has two divalent linking groups A directly connected to one benzene ring at the meta-position to each other, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that this contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B3) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B3) include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2- Methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene) ) bisoxy] bisaniline and the like.

The diamine represented by formula (B4) (hereinafter sometimes referred to as "diamine (B4)") is an aromatic diamine having four benzene rings. This diamine (B4) has high flexibility due to the fact that the amino group directly connected to at least one benzene ring and the divalent linking group A are in the meta position, and improve the flexibility of the polyimide molecular chain. considered to contribute. Therefore, the use of the diamine (B4) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO-, or -CONH-.

Diamines (B4) include bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis Examples include [4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, bis[4,4'-(3-aminophenoxy)]benzanilide and the like.

The diamine represented by formula (B5) (hereinafter sometimes referred to as "diamine (B5)") is an aromatic diamine having four benzene rings. This diamine (B5) has two divalent linking groups A directly connected to at least one benzene ring at the meta position to each other, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B5) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B5) include 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, and the like. .

The diamine represented by formula (B6) (hereinafter sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. Since this diamine (B6) has at least two ether bonds, it has high flexibility, and is considered to contribute to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B6) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -C(CH ₃ ) ₂ -, -O-, -SO ₂ -, or -CO-.

Examples of the diamine (B6) include 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4 -(4-aminophenoxy)phenyl]sulfone (BAPS), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK) and the like.

The diamine represented by formula (B7) (hereinafter sometimes referred to as "diamine (B7)") is an aromatic diamine having four benzene rings. Since this diamine (B7) has highly flexible divalent linking groups A on both sides of the diphenyl skeleton, it is believed that this contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B7) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B7) include bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl and the like.

The thermoplastic polyimide forming the adhesive layer contains a diamine residue derived from a diamine compound other than the dimer acid-type diamine and diamines (B1) to (B7) within a range that does not impair the effects of the invention. As the diamine residue derived from a diamine compound other than the dimer acid type diamine and the diamines (B1) to (B7), the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer in the insulating resin layer described above is used. Residues of those exemplified as diamine compounds can be mentioned.

In the thermoplastic polyimide forming the adhesive layer, the types of the tetracarboxylic acid residues and diamine residues, and the respective molar ratios when applying two or more types of tetracarboxylic acid residues or diamine residues are selected. The thermal expansion coefficient, tensile modulus, glass transition temperature, etc. can be controlled by Further, when the thermoplastic polyimide has a plurality of structural units of polyimide, it may exist as a block or may exist randomly, but it is preferable to exist randomly.

The imide group concentration of the thermoplastic polyimide is preferably 33% by weight or less. Here, "imide group concentration" means a value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 33% by weight, the molecular weight of the resin itself becomes small, and the low hygroscopicity deteriorates due to the increase in polar groups. In the present embodiment, by selecting the combination of the above diamine compounds, the orientation of the molecules in the thermoplastic polyimide is controlled, thereby suppressing the increase in CTE accompanying the decrease in imide group concentration and ensuring low hygroscopicity. is doing. Further, if the hygroscopicity of polyimide becomes high, the dielectric properties of the polyimide film deteriorate, so ensuring low hygroscopicity is preferable because it can prevent an increase in dielectric constant and dielectric loss tangent.

The weight average molecular weight of the thermoplastic polyimide is, for example, preferably within the range of 10,000 to 400,000, more preferably within the range of 20,000 to 350,000. When the weight-average molecular weight is less than 10,000, the strength of the adhesive layer is lowered and the adhesive layer tends to become brittle. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven thickness of the adhesive layer and streaks tend to occur during coating.

Since the thermoplastic polyimide forming the adhesive layer is interposed between, for example, the insulating resin layer and the wiring layer of the circuit board, a completely imidized structure is most preferable in order to suppress the diffusion of copper. . However, part of the polyimide may be amic acid. The imidization rate is around 1015 cm ⁻¹ by measuring the infrared absorption spectrum of the polyimide thin film by the single reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation). can be calculated from the absorbance of C═O stretching derived from the imide group at 1780 cm ⁻¹ based on the benzene ring absorber of .

(crosslink formation)
When the thermoplastic polyimide forming the adhesive layer has a ketone group, the ketone group is reacted with the amino group of an amino compound having at least two primary amino groups as functional groups to form a C=N bond. A crosslinked structure can be formed by allowing the By forming a crosslinked structure, the heat resistance of the thermoplastic polyimide forming the adhesive layer can be improved. Preferred tetracarboxylic anhydrides for forming thermoplastic polyimides having ketone groups include, for example, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), and preferred diamine compounds include , 4,4′-bis(3-aminophenoxy)benzophenone (BABP) and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB).

Examples of the amino compound that can be used for crosslinking the thermoplastic polyimide that forms the adhesive layer include dihydrazide compounds, aromatic diamines, and aliphatic amines. Among these, dihydrazide compounds are preferred. When a dihydrazide compound is used, the curing time after cross-linking can be shortened compared to when other amino compounds are used. Examples of dihydrazide compounds include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and maleic acid. dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoedioic acid dihydrazide, 4,4-bisbenzene dihydrazide, 1,4 Dihydrazide compounds such as -naphthoic acid dihydrazide, 2,6-pyridinedioic acid dihydrazide, and itaconic acid dihydrazide are preferred. The above dihydrazide compounds may be used alone or in combination of two or more.

<Production of adhesive layer>
The thermoplastic polyimide forming the adhesive layer can be produced by reacting the tetracarboxylic dianhydride and the diamine compound in a solvent to form a polyamic acid, followed by heat ring closure. For example, a tetracarboxylic dianhydride and a diamine compound are dissolved in an organic solvent in approximately equimolar amounts and stirred at a temperature within the range of 0 to 100° C. for 30 minutes to 24 hours for a polymerization reaction to form a polyimide precursor. A polyamic acid is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the resulting precursor is within the range of 5 to 50% by weight, preferably within the range of 10 to 40% by weight. Examples of organic solvents used in the polymerization reaction 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, diglyme, triglyme, cresol and the like. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such an organic solvent to be used is not particularly limited, but the amount used is adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight. is preferred.

It is usually advantageous to use the synthesized polyamic acid as a reaction solvent solution, but if necessary, it can be concentrated, diluted, or replaced with another organic solvent. Polyamic acid is also advantageously used because it is generally excellent in solvent solubility. The viscosity of the polyamic acid solution is preferably in the range of 500 cps to 100,000 cps. If the thickness is out of this range, defects such as thickness unevenness and streaks are likely to occur in the film during the coating operation using a coater or the like.

The method of forming a thermoplastic polyimide by imidizing a polyamic acid is not particularly limited, for example, heat treatment such as heating in the solvent at a temperature within the range of 80 to 400 ° C. for 1 to 24 hours is preferable. adopted by

When cross-linking the thermoplastic polyimide obtained as described above, the above amino compound is added to a resin solution containing a thermoplastic polyimide having a ketone group, and the ketone group in the thermoplastic polyimide and the amino compound are combined. Condensation reaction with primary amino groups. Due to this condensation reaction, the resin solution is cured into a cured product. In this case, the amount of the amino compound added is 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, more preferably 0.005 mol to 1.2 mol in total of the primary amino group per 1 mol of the ketone group. The amino compound can be added at 0.03 mol to 0.9 mol, most preferably 0.04 mol to 0.5 mol. If the amount of the amino compound added is such that the total amount of primary amino groups is less than 0.004 mol with respect to 1 mol of the ketone group, the cross-linking of the thermoplastic polyimide by the amino compound is not sufficient. The heat resistance tends to be difficult to develop in the adhesive layer, and if the amount of the amino compound added exceeds 1.5 mol, the unreacted amino compound acts as a thermoplastic and tends to lower the heat resistance of the adhesive layer.

Conditions for the condensation reaction for cross-linking are not particularly limited as long as the ketone groups in the thermoplastic polyimide react with the primary amino groups of the amino compound to form imine bonds (C=N bonds). The temperature of the heat-condensation is, for example, 120° C. for reasons such as releasing water generated by the condensation to the outside of the system or simplifying the condensation step when the heat-condensation reaction is subsequently performed after synthesis of the thermoplastic polyimide. It is preferably within the range of -220°C, more preferably within the range of 140-200°C. The reaction time is preferably about 30 minutes to 24 hours, and the end point of the reaction is, for example, 1670 cm by measuring the infrared absorption spectrum using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation). It can be confirmed by the reduction or disappearance of the absorption peak derived from the ketone group in the polyimide resin around ⁻¹ and the appearance of the absorption peak derived from the imine group around 1635 cm ⁻¹ .

The thermal condensation of the ketone group of the thermoplastic polyimide and the primary amino group of the amino compound is, for example, (a) a method of adding an amino compound and heating following synthesis (imidation) of the thermoplastic polyimide, ( b) A method in which an excess amount of an amino compound is charged in advance as a diamine component, and following synthesis (imidization) of the thermoplastic polyimide, the thermoplastic polyimide is heated together with the remaining amino compound that does not participate in imidization or amidation, or , (c) After processing the thermoplastic polyimide composition (adhesive polyimide resin composition described later) to which an amino compound is added into a predetermined shape (for example, after coating it on an arbitrary substrate or after forming it into a film) ), and the like.

(Thickness of adhesive layer)
The thickness of the adhesive layer is, for example, preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.3 to 50 μm. In the three-layer metal-clad laminate of the present embodiment, if the thickness of the adhesive layer is less than the above lower limit, problems such as insufficient adhesiveness may occur. On the other hand, if the thickness of the adhesive layer exceeds the above upper limit, problems such as reduced dimensional stability will occur. From the viewpoint of reducing the dielectric constant and dielectric loss tangent of the entire insulating layer, which is a laminate of the insulating resin layer and the adhesive layer, the thickness of the adhesive layer is preferably 3 μm or more.

(CTE of adhesion layer)
The thermoplastic polyimide forming the adhesive layer has high thermal expansion, and has a CTE of preferably 35 ppm/K or more, more preferably 35 ppm/K or more and 80 ppm/K or less, still more preferably 35 ppm/K or more and 70 ppm/K or more. It is within the range of K or less. A polyimide layer having a desired CTE can be obtained by appropriately changing the combination of raw materials to be used, thickness, and drying/curing conditions.

(Dielectric loss tangent of adhesive layer)
For example, when the adhesive layer is applied to a circuit board, the dielectric loss tangent (Tan δ) at 10 GHz is 0.004 or less, more preferably 0.001 or more and 0.004 or less in order to suppress deterioration of dielectric loss. Among them, it is more preferably in the range of 0.002 or more and 0.003 or less. If the dielectric loss tangent of the adhesive layer at 10 GHz exceeds 0.004, problems such as loss of electrical signals on the transmission path of high-frequency signals tend to occur when used in circuit boards such as FPCs. On the other hand, the lower limit of the dielectric loss tangent of the adhesive layer at 10 GHz is not particularly limited.

(Dielectric constant of adhesive layer)
The adhesive layer preferably has a dielectric constant of 4.0 or less at 10 GHz in order to ensure impedance matching when applied as an insulating layer of a circuit board, for example. If the dielectric constant of the adhesive layer exceeds 4.0 at 10 GHz, the dielectric loss of the adhesive layer will deteriorate when used in a circuit board such as an FPC, resulting in problems such as loss of electrical signals on the transmission path of high-frequency signals. becomes more likely to occur.

(filler)
The adhesive layer may contain a filler as needed. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, metal salts of organic phosphinic acids, and the like. These can be used singly or in combination of two or more.

<Metal layer>
The material of the metal layer in the metal-clad laminate of the present embodiment is not particularly limited, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, and tantalum. , titanium, lead, magnesium, manganese and alloys thereof. Among these, copper or a copper alloy is particularly preferable. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is also the same as that of the metal layer.

The thickness of the metal layer is not particularly limited. For example, when copper foil is used as the metal layer, the thickness is preferably 35 μm or less, more preferably in the range of 5 to 25 μm. The lower limit of the thickness of the copper foil is preferably 5 μm from the viewpoint of production stability and handling. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Moreover, as a copper foil, the copper foil marketed can be used.

(Antirust treatment)
When a copper foil is used as the metal layer in the present embodiment, the copper foil is formed on the base material copper foil and the surface of the base material copper foil on the side where the adhesive layer (or the insulating resin layer) is formed. It is preferable to have an anticorrosive layer. The anticorrosion treatment can suppress a decrease in adhesive strength between the copper foil and the adhesive layer during wiring processing of the metal-clad laminate, and can suppress a decrease in resistance to chemical solutions due to etching. The base copper foil may be either electrolytic copper foil or rolled copper foil. The thickness of the base material copper foil is not particularly limited as long as it is within the thickness range of copper foils used in general copper-clad laminates, but from the viewpoint of the flexibility of copper-clad laminates, it is 70 μm or less. Preferably. If the thickness exceeds 70 μm, the use of the obtained copper-clad laminate is limited, which is not preferable. Further, when the copper-clad laminate is used as a flexible copper-clad laminate, the thickness of the base material copper foil is preferably in the range of 5 to 35 μm. If the thickness of the base material copper foil is less than 5 μm, wrinkles tend to occur during production, and production of a thin copper foil tends to be costly. When it is used, it tends to be insufficient to reduce the thickness and size of an IC mounting substrate or the like that drives a liquid crystal display, which is the display portion of a personal computer, a mobile phone, or a personal digital assistant (PDA).

From the viewpoint of improving the adhesive strength (peel strength) between the base material copper foil, the copper foil, and the adhesive layer and the chemical resistance, it is preferable to use one whose surface has been subjected to a roughening treatment. Then, the ten-point average roughness (Rz) of the base copper foil is preferably, for example, 1.5 μm or less from the viewpoint of the above viewpoint and the flexibility and conductor loss reduction of the resulting copper-clad laminate. It is more preferably in the range of 0.1 to 1.0 μm.

The antirust treatment layer according to the present invention is a layer having antirust properties formed on the surface of the base material copper foil on the side where the adhesive layer is formed. In the present invention, by forming such an antirust treatment layer on the base copper foil, the base copper foil is provided with sufficient rust prevention properties, and the adhesive strength between the adhesive layer and the copper foil is improved. can be improved. The thickness of such an anticorrosive layer is preferably in the range of 10 to 50 nm, for example. If the thickness is less than the lower limit, the surface of the base copper foil is not uniformly covered, and it tends to be difficult to obtain a sufficient antirust effect. properties (etchability) tend to be insufficient.

It is preferable that the antirust layer includes a zinc-containing plating layer and a chromate layer. Such a treatment layer is formed by plating the surface of the base material copper foil with a plating solution containing a zinc compound to form a zinc plating treatment layer, and further by providing a chromate treatment layer. The rust effect and adhesion with the adhesive layer can be further improved. The chromate treatment layer can be formed by subjecting the surface of the antirust treatment layer to immersion or electrolytic chromate treatment using a chromate treatment agent containing chromium oxide or the like.

Moreover, it is preferable that the content of zinc in the antirust layer is 0.01 mg/dm ² or more. If the zinc content is less than the above lower limit, the solubility (etchability) of the rust-preventing layer in a copper etchant becomes insufficient, and the rust-preventing layer is separated from the adhesive layer by heat deterioration during the production of the copper-clad laminate. The adhesive strength between the copper foil tends to be insufficient. In addition, from the viewpoint of further improving the etchability of the antirust treatment layer and the adhesive strength between the adhesive layer and the copper foil, the zinc content is preferably in the range of 0.01 to 1.5 mg/dm ² . more preferred.

Furthermore, the antirust treatment layer may contain a metal other than zinc. Examples of metals other than zinc include nickel, cobalt, and molybdenum. For example, it is preferable that the content of nickel in the antirust layer is 0.1 mg/dm ² or more. If the nickel content is less than the above lower limit, the rust-preventing effect on the copper foil surface is not sufficient, and the copper foil surface tends to discolor after heating or in a high-temperature or high-humidity environment. Further, from the viewpoint of sufficiently preventing diffusion of copper from the base material copper foil to the antirust treatment layer and the adhesive layer, the nickel content is more preferably in the range of 0.1 to 3 mg/dm ² . .

Nickel is completely solid with respect to copper and can create an alloy state, or nickel easily diffuses with copper and creates an alloy state. In such a state, the electrical resistance is higher than that of pure copper, in other words, the electrical conductivity is lower. For this reason, when the anticorrosion treatment layer contains a large amount of nickel, the resistance of copper alloyed with nickel increases. As a result, loss during signal transmission increases due to increased resistance of signal wiring due to the skin effect. From this point of view, when the copper clad laminate of the present embodiment is used in a process for a circuit board or the like that performs high frequency transmission of 10 GHz, for example, it is preferable to suppress the amount of nickel to 0.01 mg/dm ² or less. .

When the amount of nickel in the antirust layer is suppressed to 0.01 mg/dm ² or less, the antirust layer preferably contains at least cobalt and molybdenum. Such an antirust treatment layer contains 0.01 mg/dm ² or less of nickel, 0.01 to 0.5 mg/dm ² of cobalt, and 0.01 to 0.5 mg/dm ² of molybdenum. It is preferably within the range and the total amount of cobalt element and molybdenum element (Co+Mo) is controlled to be within the range of 0.1 to 0.7 mg/dm ² . By setting it within such a range, it is possible to suppress the etching residue of the resin part between the wirings during the wiring processing of the copper clad laminate, suppress the deterioration of resistance to chemicals due to etching, and the adhesive strength and strength between the copper foil and the resin. A decrease in long-term reliability can be suppressed.

Further, the copper foil used for the copper-clad laminate of the present embodiment is subjected to the above-described anticorrosion treatment, and for the purpose of improving the adhesive strength, the surface of the copper foil is coated with, for example, siding, aluminum alcoholate, aluminum chelate, silane. A surface treatment with a coupling agent or the like may be applied.

<Method for producing metal-clad laminate>
A metal-clad laminate, for example, is prepared by preparing a resin film in which an adhesive layer and an insulating resin layer are laminated, sputtering metal on the adhesive layer side to form a seed layer, and then forming a metal layer by plating, for example. may be prepared by

A metal-clad laminate is prepared by preparing a resin film in which an adhesive layer and an insulating resin layer are laminated, and laminating a metal foil such as copper foil on the adhesive layer side by a method such as thermocompression bonding. may

Furthermore, a metal-clad laminate is obtained by casting a coating liquid for forming an adhesive layer on a metal foil such as a copper foil, drying it to form a coating film, and forming an insulating resin layer on the coating film. It may be prepared by casting a coating liquid for coating, drying it to form a coating film, and then heat-treating it all at once. In this case, as the coating liquid for forming the adhesive layer, an adhesive polyimide resin composition (described later) or a polyamic acid solution that is a precursor of the thermoplastic polyimide that forms the adhesive layer can be used. Further, the thermoplastic polyimide forming the adhesive layer may be crosslinked by the above method.

[Circuit board]
The metal-clad laminate of the present embodiment is mainly useful as a circuit board material for FPCs, rigid-flex circuit boards, and the like. That is, the FPC according to one embodiment of the present invention can be manufactured by patterning the metal layer of the metal-clad laminate according to this embodiment into a pattern to form a wiring layer.

[Adhesive sheet]
The adhesive sheet of the present embodiment comprises an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer. It is an adhesive sheet for forming the adhesive layer in the metal-clad laminate. This adhesive sheet is formed by forming the thermoplastic polyimide that forms the above-mentioned adhesive layer into a sheet. That is, the thermoplastic polyimide forming the adhesive sheet contains predetermined amounts of tetracarboxylic acid residues and diamine residues, like the adhesive layer.

The adhesive sheet may be in a state of being laminated on any base material such as copper foil, glass plate, polyimide film, polyamide film, polyester film, and the like. The thickness, thermal expansion coefficient, dielectric loss tangent, dielectric constant, etc. of the adhesive sheet conform to those of the adhesive layer. In addition, the adhesive sheet can contain optional components such as fillers.

As an aspect of the method for producing an adhesive sheet of the present embodiment, for example, [1] a support substrate is coated with a polyamic acid solution, dried, imidized by heat treatment, and then peeled off from the support substrate to form an adhesive sheet. [2] A method of applying a polyamic acid solution to a supporting substrate and drying it, then peeling off the polyamic acid gel film from the supporting substrate and heat-treating it to imidize it to produce an adhesive sheet, [ 3] A method of producing an adhesive sheet by applying a solution of an adhesive polyimide resin composition (described later) to a supporting substrate, drying the solution, and then peeling the solution from the supporting substrate. The thermoplastic polyimide constituting the adhesive sheet may be crosslinked by the above method.

The method of applying the polyimide solution (or polyamic acid solution) onto the supporting substrate is not particularly limited, and it can be applied, for example, by a comma, die, knife, lip coater, or the like. The adhesive sheet to be produced is preferably formed by applying a polyimide solution in which imidization has been completed in a polyamic acid solution onto a supporting substrate and drying. Since the polyimide of the present embodiment is solvent-soluble, it is advantageous in that the polyamic acid can be imidized in a solution state and used as it is as a polyimide coating liquid.

The adhesive sheet obtained as described above has excellent flexibility and dielectric properties (low dielectric constant and low dielectric loss tangent) when it is used to form an adhesive layer of a circuit board. It has favorable properties as an adhesive layer for rigid-flex circuit boards and the like.

[Adhesive polyimide resin composition]
The adhesive polyimide resin composition of the present embodiment comprises an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal laminated on the insulating resin layer via the adhesive layer. It is for forming the adhesive layer in a metal-clad laminate having a layer. The adhesive polyimide resin composition contains a polyimide containing a tetracarboxylic acid residue and a diamine residue. 50 mol parts or more of a diamine residue derived from a dimer acid-type diamine substituted with a high-grade aminomethyl group or an amino group, for example, within the range of 50 mol parts or more and 99 mol parts or less, preferably 80 mol parts or more, For example, contained within the range of 80 mol parts or more and 99 mol parts or less, relative to 100 mol parts of the tetracarboxylic acid residue, a tetracarboxylic anhydride represented by the general formula (1) and / or (2) contains 90 mol parts or more of tetracarboxylic acid residues derived from substances.

In addition, the adhesive polyimide resin composition contains at least one diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the general formulas (B1) to (B7), and 1 mol part or more and 50 mol parts of the diamine residue. It is preferable to contain within the following range.

The adhesive polyimide resin composition of the present embodiment is solvent-soluble and can contain an organic solvent as an optional component. Preferred organic solvents include, for example, N,N-dimethylformamide, N,N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, 2-butanone, dimethylsulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, Examples include diglyme and triglyme. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination.

The adhesive polyimide resin composition of the present embodiment further includes, as another optional component, an amino compound having at least two primary amino groups used for cross-linking as functional groups, an inorganic filler, a plasticizer, an epoxy Other resin components such as resins, curing accelerators, coupling agents, fillers, pigments, solvents, flame retardants and the like can be appropriately blended.

The adhesive polyimide resin composition obtained as described above has excellent flexibility and dielectric properties (low dielectric constant and low dielectric loss tangent) when it is used to form an adhesive layer or adhesive sheet. , for example, as a material for forming adhesive layers of FPCs, rigid-flex circuit boards, and the like.

EXAMPLES The present invention will be specifically described below by way of examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, various measurements and evaluations are as follows.

[Measurement of coefficient of thermal expansion (CTE)]
A polyimide film with a size of 3 mm × 20 mm is heated from 30 ° C. to 300 ° C. at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). Further, after holding at that temperature for 10 minutes, it was cooled at a rate of 5°C/min, and the average thermal expansion coefficient (thermal expansion coefficient) from 250°C to 100°C was obtained.

[Measurement of surface roughness of copper foil]
The surface roughness of the copper foil is measured by AFM (manufactured by Bruker AXS, trade name: Dimension Icon type SPM), probe (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip curvature radius 10 nm, Using a spring constant of 42 N/m), measurements were made on the surface of the copper foil in an area of 80 μm×80 μm in tapping mode to obtain the ten-point average roughness (Rzjis).

[Measurement of metal elements on the surface of copper foil subjected to metal deposition treatment]
After masking the back surface of the analysis surface of the copper foil, dissolve the analysis surface with 1N-nitric acid, adjust the volume to 100 mL, and then measure using an inductively coupled plasma atomic emission spectrometer (ICP-AES) Optima 4300 manufactured by PerkinElmer. did.

[Warpage evaluation method]
The evaluation of warpage was performed by the following method. A film of 10 cm×10 cm was placed, and the average warped height at the four corners of the film was measured.

[Measurement of dielectric constant (Dk) and dielectric loss tangent (Df)]
Permittivity and dielectric loss tangent are measured using a cavity resonator perturbation method permittivity evaluation device (manufactured by Agilent, trade name; vector network analyzer E8363C) and a split post dielectric resonator (SPDR resonator), and a resin sheet at a frequency of 10 GHz. (or an insulating layer in which a resin sheet is laminated on an insulating resin layer) was measured for dielectric constant and dielectric loss tangent. The resin sheet (or the insulating layer in which the resin sheet is laminated on the insulating resin layer) used for the measurement was left for 24 hours under conditions of temperature: 24 to 26° C. and humidity: 45 to 55%.

[Evaluation method for laser processability]
Evaluation of laser processability was performed by the following method. UV-YAG, third harmonic 355 nm laser light is irradiated at a frequency of 60 kHz and an intensity of 1.0 W to process a bottomed via. When gouges or undercuts occurred in the coating layer, it was evaluated as "not acceptable".

[Measurement of peel strength]
Peel strength was measured by the following method. Using a tensile tester (Strograph VE manufactured by Toyo Seiki Seisakusho Co., Ltd.), the peel strength was measured when an insulating resin layer with a test piece width of 5 mm was pulled in the 90° direction of the adhesive layer at a speed of 50 mm/min. A peel strength of 0.9 kN/m or more is "good", a peel strength of 0.4 kN/m or more and less than 0.9 kN/m is "acceptable", and a peel strength of less than 0.4 kN/m is "improper". evaluated.

The abbreviations used in the examples represent the following compounds.
BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride BPDA: 3,3',4,4'-diphenyltetracarboxylic dianhydride 6FDA: 4,4'-(hexafluoroisopropylidene ) Diphthalic anhydride BPADA: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride PMDA: pyromellitic dianhydride APB: 1,3-bis(3-aminophenoxy ) Benzene BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane DDA: Aliphatic diamine having 36 carbon atoms (manufactured by Croda Japan Co., Ltd., trade name; PRIAMINE1074, amine value: 210 mgKOH/g, cyclic mixture of dimer diamines with structure and chain structure, content of dimer component; 95% by weight or more)
m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl ODPA: 4,4'-oxydiphthalic anhydride (also known as 5,5'-oxybis-1,3-isobenzofurandione)
N-12: dodecanedioic acid dihydrazide NMP: N-methyl-2-pyrrolidone DMAc: N,N-dimethylacetamide

(Synthesis example 1)
<Preparation of resin solution for adhesive layer>
A 1000 ml separable flask was charged with 56.18 g of BTDA (0.174 mol), 93.82 g of DDA (0.176 mol), 210 g of NMP and 140 g of xylene and mixed well at 40° C. for 1 hour. Then, a polyamic acid solution was prepared. The polyamic acid solution was heated to 190 ° C., heated and stirred for 4 hours, and 140 g of xylene was added to complete imidation. Polyimide solution 1 (solid content: 30% by weight, viscosity: 5,100 cps, weight average molecular weight 66, 100) were prepared.

(Synthesis Examples 2-10)
<Preparation of resin solution for adhesive layer>
Polyimide solutions 2 to 10 were prepared in the same manner as in Synthesis Example 1, except that the raw material compositions shown in Table 1 were used.

(Synthesis Example 11)
<Preparation of resin solution for adhesive layer>
100 g of polyimide solution 1 prepared in Synthesis Example 1 (30 g as solid content) was blended with 1.1 g of N-12 (0.004 mol), and diluted by adding 0.1 g of NMP and 10 g of xylene, A polyimide solution 11 was prepared by further stirring for 1 hour.

(Synthesis Examples 12-17)
<Preparation of resin solution for adhesive layer>
Polyimide solutions 12 to 17 were prepared in the same manner as in Synthesis Example 11, except that polyimide solutions 5 to 10 shown in Table 2 were used.

(Synthesis Example 18)
<Preparation of polyimide film for insulating resin layer>
2.196 g of DDA (0.0041 mol), 16.367 g of m-TB (0.0771 mol) and 212.5 g of DMAc are added to a 300 ml separable flask under a nitrogen stream and stirred at room temperature. to dissolve. Next, after adding 4.776 g of BPDA (0.0162 mol) and 14.161 g of PMDA (0.0649 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours, and polyamic acid solution P (viscosity 26,000 cps) were prepared.

The polyamic acid solution P was evenly applied to a copper foil (surface roughness Rz: 2.1 μm) so that the thickness after curing was about 25 μm, and then dried by heating at 120° C. to remove the solvent. Further, stepwise heat treatment was performed from 120° C. to 360° C. to complete imidization, and a metal-clad laminate P was prepared. A polyimide film P (CTE; 20 ppm/K, Dk; 2.95, Df; 0.0041) was prepared by removing the copper foil from the metal-clad laminate P by etching using an aqueous solution of ferric chloride.

(Production example 1)
<Preparation of resin sheet for adhesive layer>
A resin sheet 1a (thickness: 25 μm) was prepared by coating the polyimide solution 1 on one side of a release-treated PET film, drying it at 80° C. for 15 minutes, and peeling it off. Table 3 shows the dielectric constant (Dk) and dielectric loss tangent (Df) of the resin sheet 1a.

(Production Examples 2 to 7)
<Preparation of resin sheet for adhesive layer>
Using the polyimide solution 1, resin sheets 1b to 1g were prepared in the same manner as in Production Example 1, but with different thicknesses. Table 3 shows the dielectric constant (Dk) and dielectric loss tangent (Df) of the resin sheets 1b to 1g.

(Production Examples 8 to 16)
<Preparation of resin sheet for adhesive layer>
Resin sheets 2a to 10a each having a thickness of 25 μm were prepared in the same manner as in Production Example 1, except that the polyimide solution shown in Table 4 was used. Table 4 shows the dielectric constant (Dk) and dielectric loss tangent (Df) of the resin sheets 2a to 10a.

(Production example 17)
<Preparation of copper foil with antirust treatment>
An electrolytic copper foil (thickness: 12 μm, surface roughness Rz in MD (Machine Direction; flow direction of long copper foil) on the resin layer side: 0.3 μm) was prepared. After roughening the surface of this copper foil, it was subjected to plating treatment (metal deposition treatment) containing predetermined amounts of cobalt and molybdenum, and further zinc plating and chromate treatment were sequentially performed to obtain a copper foil 1 (Ni; 0. 01 mg/dm ² or less, Co; 0.23 mg/dm ² , Mo; 0.36 mg/dm ² , Zn; 0.11 mg/dm ² , Cr; 0.14 mg/dm ² ).

[Example 1]
A resin sheet 1a (thickness: 25 μm, Dk: 2.4, Df: 0.0020) is placed on a copper foil 1 (surface roughness Rz: 0.3 μm), and a polyimide film 1 (Toray manufactured by DuPont, trade name: Kapton EN-S, thickness: 25 μm, CTE: 16 ppm/K, Dk: 3.79, Df: 0.0126), temperature 170° C., pressure 0.85 MPa, A copper-clad laminate 1 was prepared by vacuum laminating for 1 minute and then heating in an oven at 160° C. for 1 hour. Table 5 shows the evaluation results of the copper-clad laminate 1.

[Example 2]
A copper-clad laminate 2 was prepared in the same manner as in Example 1, except that a resin sheet 1g (thickness: 50 µm, Dk: 2.4, Df: 0.0020) was used instead of the resin sheet 1a. Table 5 shows the evaluation results of the copper-clad laminate 2.

[Example 3]
A resin sheet 1g was used instead of the resin sheet 1a, and a liquid crystal polymer film 3 (manufactured by Kuraray Co., Ltd., trade name; CT-Z, thickness; 50 μm, CTE; 18 ppm/K, Dk; 3.40, Df: 0.0022), a copper-clad laminate 3 was prepared in the same manner as in Example 1. Table 5 shows the evaluation results of the copper-clad laminate 3.

The results of Examples 1 to 3 are summarized in Table 5.

[Example 4]
Polyimide solution 1 was applied to one side of polyimide film P prepared in Synthesis Example 18 and dried at 80° C. for 15 minutes to prepare insulating film 4 (adhesive layer thickness: 3 μm). With the adhesive layer surface of the insulating film 4 overlaid on the antirust-treated surface of the copper foil 1, vacuum lamination is performed under the conditions of a temperature of 170° C., a pressure of 0.85 MPa, and a time of 1 minute. A copper-clad laminate 4 was prepared by heating for one hour. Table 6 shows the evaluation results of the copper-clad laminate 4.

[Example 5]
A copper-clad laminate 5 was prepared in the same manner as in Example 4, except that the adhesive layer had a thickness of 1 μm. Table 6 shows the evaluation results of the copper-clad laminate 5.

[Example 6]
A copper-clad laminate 6 was prepared in the same manner as in Example 4, except that the adhesive layer had a thickness of 0.3 μm. Table 6 shows the evaluation results of the copper-clad laminate 6.

The results of Examples 4 to 6 are summarized in Table 6.

[Example 7]
The polyimide solution 1 was applied to the polyimide film surface of the copper clad laminate 4 prepared in Example 4 and dried at 80° C. for 15 minutes to make the thickness of the adhesive layer 3 μm. With the treated surface overlaid on the adhesive layer surface, vacuum lamination is performed under the conditions of a temperature of 170 ° C., a pressure of 0.85 MPa, and a time of 1 minute. Laminate 7 was prepared. Table 7 shows the evaluation results of the copper-clad laminate 7.

[Example 8]
A copper-clad laminate 8 was prepared in the same manner as in Example 7, except that the adhesive layer had a thickness of 1 μm. Table 7 shows the evaluation results of the copper-clad laminate 8.

[Example 9]
A copper-clad laminate 9 was prepared in the same manner as in Example 7, except that the adhesive layer had a thickness of 0.3 μm. Table 7 shows the evaluation results of the copper-clad laminate 9.

The results of Examples 7 to 9 are summarized in Table 7.

[Example 10]
Polyimide solution 1 was applied to one side of polyimide film 1 and dried at 80° C. for 15 minutes to prepare insulating film 5 (adhesive layer thickness: 12 μm). With the adhesive layer surface of the insulating film 5 overlaid on the antirust-treated surface of the copper foil 1, vacuum lamination is performed under the conditions of a temperature of 170° C., a pressure of 0.85 MPa, and a time of 1 minute. A copper-clad laminate 10 was prepared by heating for one hour. Table 8 shows the evaluation results of the copper-clad laminate 10.

[Example 11]
The polyimide solution 1 was applied to the antirust-treated side of the copper foil 1 and dried at 80° C. for 15 minutes to prepare a film 6 with copper foil (adhesive layer thickness: 5 μm). The adhesive layer surface of the film 6 with copper foil and the polyimide film 2 (manufactured by Toray DuPont, trade name: Kapton EN, thickness: 5 μm, CTE: 16 ppm/K, Dk: 3.70, Df: 0.0076) were overlaid. In this state, vacuum lamination was performed at a temperature of 170° C. and a pressure of 0.85 MPa for 1 minute, followed by heating in an oven at a temperature of 160° C. for 1 hour to prepare a copper-clad laminate 11 . Table 8 shows the evaluation results of the copper-clad laminate 11.

[Example 12]
A polyimide solution 13 was applied to the polyimide film surface of the copper-clad laminate 4 prepared in Example 4 and dried at 80° C. for 15 minutes to make the thickness of the adhesive layer 25 μm. With the treated surface overlaid on the adhesive layer surface, vacuum lamination is performed under the conditions of a temperature of 170 ° C., a pressure of 0.85 MPa, and a time of 1 minute. A laminate 12 was prepared. Table 8 shows the evaluation results of the copper-clad laminate 12.

[Example 13]
A polyimide solution 16 was applied to the polyimide film surface of the copper-clad laminate 4 prepared in Example 4 and dried at 80° C. for 15 minutes to make the thickness of the adhesive layer 25 μm. With the treated surface overlaid on the adhesive layer surface, vacuum lamination is performed under the conditions of a temperature of 170 ° C., a pressure of 0.85 MPa, and a time of 1 minute. Laminate 13 was prepared. Table 8 shows the evaluation results of the copper-clad laminate 13.

(Synthesis Examples 19-21)
<Preparation of resin solution for adhesive layer>
Polyimide solutions 19 to 21 were prepared in the same manner as in Synthesis Example 1 except that the raw material compositions shown in Table 9 were used.

(Production Examples 18-20)
<Preparation of resin sheet for adhesive layer>
Resin sheets 18a to 20a having a thickness of 25 μm were prepared in the same manner as in Production Example 1 except that the polyimide solution shown in Table 10 was used. Table 10 shows the dielectric constant (Dk) and dielectric loss tangent (Df) of the resin sheets 18a to 20a.

(Comparative example 1)
Polyimide solution 19 was applied to one side of polyimide film 1 and dried at 80° C. for 15 minutes to prepare insulating film 7 (thickness of adhesive layer: 12 μm). With the adhesive layer surface of the insulating film 7 overlaid on the antirust-treated surface of the copper foil 1, vacuum lamination is performed under the conditions of a temperature of 170°C, a pressure of 0.85 MPa, and a time of 1 minute. A copper-clad laminate 18 was prepared by heating for one hour. Table 11 shows the evaluation results of the copper-clad laminate 18.

(Comparative example 2)
A copper-clad laminate 19 was prepared in the same manner as in Comparative Example 1, except that the polyimide solution 20 was used. Table 11 shows the evaluation results of the copper-clad laminate 19.

(Comparative Example 3)
A copper-clad laminate 20 was prepared in the same manner as in Comparative Example 1, except that the polyimide solution 21 was used. Table 11 shows the evaluation results of the copper-clad laminate 20.

Although the embodiments of the present invention have been described above in detail for the purpose of illustration, the present invention is not limited to the above embodiments and various modifications are possible.

Claims (4)

A metal-clad laminate comprising an insulating resin layer, an adhesive layer laminated on at least one surface of the insulating resin layer, and a metal layer laminated on the insulating resin layer via the adhesive layer,
The metal layer is made of copper foil, and the surface of the copper foil in contact with the adhesive layer has an antirust treatment layer containing a zinc-containing plating layer and a chromate treatment layer formed by antirust treatment, and The antirust layer has a nickel content of 0.01 mg/dm ² or less, a cobalt content of 0.01 to 0.5 mg/dm ² , and a molybdenum content of 0.01 to 0.5 mg/dm ² . within the range, and the total amount of cobalt element and molybdenum element (Co + Mo) is within the range of 0.1 to 0.7 mg / dm ² ,
The adhesive layer has a polyimide containing a tetracarboxylic acid residue and a diamine residue,
The polyimide, with respect to 100 mole parts of the diamine residue,
A metal clad laminate characterized by containing 50 mol parts or more of a diamine residue derived from a dimer acid-type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups. board. The polyimide, with respect to 100 mole parts of the tetracarboxylic acid residue,
2. The composition according to claim 1, containing a total of 90 mol parts or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formulas (1) and/or (2). metal-clad laminate.

[In the general formula (1), X represents a single bond or a divalent group selected from the following formula, and in the general formula (2), the cyclic portion represented by Y is a 4-membered ring, a 5-membered ring, It represents forming a cyclic saturated hydrocarbon group selected from a ring, a 6-membered ring, a 7-membered ring and an 8-membered ring. ]

[In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, where n is Indicates an integer from 1 to 20. ] The polyimide, with respect to 100 mole parts of the diamine residue,
Containing a diamine residue derived from the dimer acid-type diamine in the range of 50 to 99 mol parts,
1 to 50 mol parts of a diamine residue derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7): 3. The metal-clad laminate according to 1 or 2.

[In the formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group or an alkoxy group having 1 to 6 carbon atoms, and the linking group A independently represents -O-, -S-, -CO a divalent group selected from -, -SO-, -SO ₂ -, -COO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -NH- or -CONH-, n ₁ is independent indicates an integer from 0 to 4. However, the formula (B3) that overlaps with the formula (B2) is excluded, and the formula (B5) that overlaps with the formula (B4) is excluded. ] A circuit board formed by processing the metal layer of the metal-clad laminate according to claim 1 or 2 into wiring.