JP2009184256A - Metal-clad laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-clad laminate which gives high adhesion to metal layers to a polyimide resin layer and prevents the occurrence of an undercut or an eaves-shaped etching residue during polyimide etching and to provide a high precision HDD suspension high in reliability obtained from he metal-clad laminate. <P>SOLUTION: The metal-clad laminate is composed of the metal layer A, the polyimide resin layer B, an adhesive layer C, and the metal layer D which are laminated in turn. The polyimide resin layer B has a thickness of 5-50 μm and a linear thermal expansion coefficient of 10×10<SP>-6</SP>-30×10<SP>-6</SP>(1/K). The thickness of the adhesive layer C is 0.1-2.0 μm. The metal-clad laminate is formed by drying and imidating a mixed solution containing a polyamide acid (B') which is the precursor of a polyimide resin composing the polyimide layer B and the precursor resin (X') of a thermoplastic polyimide resin (X). The mixed solution contains 25-85 pts.wt. of the precursor resin (B') per 100 pts.wt. of the precursor resins (B') and (X'). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a metal-clad laminate and a manufacturing method thereof, and more particularly, to a metal-clad laminate suitable for use in a hard disk drive (HDD) suspension.

  HDD production has been increasing with the recent increase in demand for personal computers and new installations in home appliances and car navigation systems. In addition, HDDs are expected to increase in capacity and miniaturization in the future, and suspension parts constituting flexure blanks that read magnetism in HDDs are becoming smaller, more diversified in wiring, and thinner. As capacity increases, most of the wireless type suspensions that have been used in the past are replaced by suspensions with integrated wiring that have stable buoyancy and positional accuracy with respect to the disk that is the storage medium. Among wiring-integrated suspensions, there is a type called a TSA (trace suspension assembly) method in which a metal-clad laminate (also called a laminate) of stainless steel foil-polyimide resin-copper foil is processed into a predetermined shape by etching.

  The method of etching polyimide is roughly divided into a dry etching type using a plasma method and a wet etching type using an alkaline solution, but the latter wet etching type method has recently been applied from the viewpoint of processing cost and the like. . In addition, with the technological innovation of suspensions such as fly-high control and microactuators, the number of signal lines has also increased, and this has led to thinner wires. Metal-clad laminates used as HDD suspension materials are also required to have metal-polyimide adhesive strength and dimensional stability during circuit processing. Further, there is no exception with respect to the etching accuracy at the time of polyimide processing, and the requirements are severe regarding the processed shape after etching. In general, the polyimide used in these suspension materials has a three-layer structure that uses thermoplastic polyimide and low thermal expansion polyimide to develop metal-polyimide bond strength when thermocompression bonding the metal. It is configured. The thermoplastic polyimide used here and the low thermal expansion polyimide have different dissolution rates (etching rates) due to the alkali treatment liquid, etc., so, for example, the etching rate of thermoplastic polyimide is faster than the etching rate of low thermal expansion polyimide. In such a case, an undercut may occur during the etching process, or on the contrary, if it is slow, a thermoplastic polyimide layer having a slow etching rate may remain in a bowl shape after the etching. With regard to suspensions that require strict cleanliness, such a polyimide shape defect may cause generation of particles during ultrasonic cleaning, or may cause malfunction when mounted on a hard disk.

  On the other hand, methods for reducing the thickness of thermoplastic polyimide and materials that do not contain thermoplastic polyimide have been proposed. For example, in Japanese Patent Application Laid-Open No. 2006-190824 (Patent Document 1), the thickness of a polyimide layer in contact with a conductor is set to 2.0 μm in order to prevent wiring sinking when an IC chip is mounted in a COF (chip on film) manufacturing process. The following laminates have been proposed. However, such a laminate does not take into account the difference in the etching rate between non-thermoplastic polyimide and thermoplastic polyimide, and tends to cause shape defects after etching of the polyimide resin layer.

  On the other hand, a method has been proposed in which the thickness ratio of the thermoplastic polyimide in the outermost layer of the non-thermoplastic polyimide is defined to control overetching or undercut during wet etching (Patent Document 2). However, with this method, it is difficult to perfectly match the etching rates of the non-thermoplastic polyimide and the thermoplastic polyimide, so it is difficult to accurately control the etching shape including overetching and undercutting. It was. Furthermore, a laminate that can be wet-etched has been proposed (Patent Document 3). However, the shape of the polyimide resin layer after the etching process cannot satisfy these severe requirements.

  Moreover, in order to control overetching and undercut during wet etching, a metal laminate having a single polyimide resin layer has been proposed (Patent Document 4). However, such a polyimide resin layer is thermoplastic and has a thermal expansion coefficient larger than that of metal due to its molecular structure, which may cause a problem in dimensional stability of the material.

JP 2006-190824 A Japanese Patent Laying-Open No. 2005-111858 JP 2002-240193 A JP 2004-276413 A

  The present invention improves the dimensional stability as a metal-clad laminate while preventing the occurrence of undercuts and wrinkle-like etching residues during polyimide etching while imparting high adhesion to the metal layer to the polyimide resin layer. Another object of the present invention is to provide a metal-clad laminate suitable for HDD suspension applications that can sufficiently meet the demand for higher-level microcircuits. Another object is to provide an HDD suspension manufactured from the metal-clad laminate.

  As a result of intensive studies to achieve the above object, the present inventors have found that when a specific adhesive layer is present between a specific polyimide resin layer and a metal layer, the metal layer of the manufactured laminate is insulated from the metal layer. It is possible to have excellent uniformity of adhesion between the surfaces of the resin layer, to control the dimensional change rate of the laminate, to be a material that does not generate warpage, and to control the shape during polyimide etching. It has been found that it becomes easy and the present invention has been completed.

That is, the present invention is a metal-clad laminate composed of a metal layer A, a polyimide resin layer B, an adhesive layer C, and a metal layer D in this order, and the polyimide resin layer B is a single layer having a thickness of 5 to 50 μm. The linear thermal expansion coefficient is 10 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), the adhesive layer C has a thickness of 0.1 to 2.0 μm, and constitutes the polyimide resin layer B. It is formed by drying and imidizing a mixed solution containing a polyamide resin (B ′) which is a polyimide resin precursor and a precursor resin (X ′) of a thermoplastic polyimide resin (X). The solution is a metal-clad laminate characterized by containing 25 to 85 parts by weight of the precursor resin (B ′) with respect to 100 parts by weight of the total of the precursor resins (B ′) and (X ′).

  Here, the glass transition temperature of the thermoplastic polyimide resin (X) is preferably in the range of 200 to 320 ° C.

  Further, 1) the total thickness of the polyimide resin layer B and the adhesive layer C is in the range of 5 to 50 μm, 2) the metal layer A is a conductive metal layer having a thickness of 0.1 to 50 μm, and the metal layer D Is a stainless steel layer having a thickness of 10 to 50 μm, or 3) the metal layer A is a stainless steel layer having a thickness of 10 to 50 μm and the metal layer D is a conductive metal layer having a thickness of 0.01 to 50 μm. Satisfying any one or more gives a better metal-clad laminate.

  The present invention also provides a metal-clad laminate for HDD suspensions comprising the above-described metal-clad laminate and a HDD suspension obtained by processing the metal-clad laminate.

  According to the present invention, an excellent metal-clad laminate can be provided because the polyimide resin layer can be provided with high adhesion to the metal layer, and undercut and hook-like etching residue can be prevented during polyimide etching. It becomes possible. Moreover, since the adhesive layer obtained by this invention can suppress the malfunction by generation | occurrence | production of foaming under high temperature heating, the industrial value is high. Therefore, it is possible to provide a highly reliable and highly accurate HDD suspension in response to the demand for a HDD suspension with high density and ultra-fine wiring.

  The metal-clad laminate of the present invention is composed of a metal layer A, a polyimide resin layer B, an adhesive layer C, and a metal layer D in this order.

  The metal layer A and the metal layer D used in the metal-clad laminate of the present invention are not particularly limited as long as the material is a layer made of metal. For example, iron, nickel, beryllium, aluminum, zinc, indium, silver , Gold, tin, zirconium, stainless steel, tantalum, titanium, copper, lead, magnesium, manganese, and metals made of these alloys. Among these, stainless steel, copper, or a copper alloy is suitable.

  When the metal layer A or the metal layer D is used for an application requiring spring characteristics or dimensional stability, the material is preferably stainless steel. When electrical conductivity is required, the material is preferably a conductive metal such as copper or a copper alloy. When one of the metal layer A or the metal layer D is required for spring characteristics and dimensional stability and the other is required for electrical conductivity, it is preferable that one material is stainless steel and the other material is a conductive metal. . As an application in which such a case occurs, there is an HDD suspension application. In addition, as both applications requiring electrical conductivity, there is a double-sided flexible printed circuit board (double-sided FPC) application.

  As the stainless steel, for example, a highly elastic and high strength stainless steel such as SUS304 is preferable. Furthermore, in order to suppress the warp of the metal-clad laminate, SUS304 annealed at a temperature of 300 ° C. or higher is preferable. When the metal-clad laminate is applied as an HDD suspension, the thickness of the stainless steel layer is preferably 10 to 50 μm, more preferably 10 to 30 μm, and still more preferably 15 to 25 μm. If the thickness of the stainless steel layer is less than 10 μm, there is a problem that it is not possible to secure the spring property that sufficiently suppresses the flying height of the slider. Become.

  As the conductive metal, copper or a copper alloy is preferable. Here, the copper alloy refers to an alloy containing copper as an essential element and containing at least one different element other than copper, such as chromium, zirconium, nickel, silicon, zinc, and beryllium. Say something more than weight percent. As the copper alloy, it is preferable to use copper having a copper content of 95% by weight or more. Examples of the metal contained in copper include chromium, zirconium, nickel, silicon, zinc, and beryllium. An alloy containing two or more of these metals may also be used.

  It is also advantageous that the conductive metal layer is made of a rolled copper foil or an electrolytic copper foil. The rolled copper foil and the electrolytic copper foil can be produced by a known method, and the former can be produced by rolling a copper ingot to a predetermined thickness and repeating heat treatment. Moreover, the electrolytic copper foil can be obtained by depositing copper sulfate as a main component from an electrolytic solution by electrolysis. When used as a HDD suspension, for example, when a fine flying lead with a circuit width of 40 μm or less is formed, a problem such as disconnection is particularly likely to occur. Therefore, the tensile strength of the laminated copper foil is 400 MPa or more. The upper limit is not particularly limited, but 1000 MPa or less is preferable. In this case, the thickness of the conductive metal layer is desirably in the range of 0.1 to 50 μm. Advantageously, copper or a copper alloy is advantageously used as the conductor metal layer, and the thickness range is 5 to 25 μm, more preferably 7 to 12 μm, and even more preferably 8 to 10 μm. In particular, when the thickness of the conductive metal layer is in the range of 5 to 10 μm, it is preferable to use a highly conductive electrolytic copper foil, and the conductivity is 95% or more, preferably 97% or more, more preferably. It is good that it is 98% or more. By using such a metal layer, it is easy to generate electrical resistance, and heat dissipation can be suppressed to a low level. As a result, impedance can be easily controlled.

  When the thickness of the conductive metal layer is 0.1 to 9 μm, from the viewpoint of handling properties in the laminate manufacturing process, the conductive metal layer is attached to the support in which the support metal layer is laminated via the release layer. It is preferable to use a conductive metal layer. The conductor metal layer from which the support metal layer has been peeled can be formed into a circuit by a subtractive method or a semi-additive method. The surface roughness of the conductive metal layer is not particularly limited, but preferably Rz is JIS = 2.0 μm or less, more preferably Rz is JIS = 1.5 μm or less from the viewpoint of flash etching property. In addition, said Rz shows the ten-point average roughness (JIS B0601-1994) in surface roughness.

  Here, the peel strength between the support metal layer and the conductor metal layer is preferably 1 N / m or more and 100 N / m or less. Preferably it is 1 N / m to 50 N / m, more preferably 3 N / m to 15 N / m, still more preferably 4 N / m to 10 N / m. When the peel strength is less than 1 N / m, the conductor metal layer may peel from the support metal layer in the laminate manufacturing process, which causes a problem in stable operation. On the other hand, when the peel strength exceeds 100 N / m, the laminated body after peeling of the support metal layer is likely to warp. The peel strength here refers to a metal foil 1 mm width 90 ° peeling method (JIS C6471). This peel strength can be changed by adjusting the adhesive strength between the support metal layer and the conductor metal layer (by using a release agent or a low-tack material).

  When the conductive metal layer has a thickness of 0.001 to 1.0 μm, the conductive metal layer can be formed by, for example, a sputtering method. Although details will be described later, when the conductor metal layer is further thickened, it can be formed into a thick film by electroless plating or electrolytic plating. Which metal layer is used as the metal layer A and the metal layer D is determined by the use of the metal-clad laminate, the adhesion between the metal layer and the polyimide resin layer, the ease of manufacturing the metal-clad laminate, and the like.

  The metal-clad laminate of the present invention has a polyimide resin layer B and an adhesive layer C in addition to the metal layer A and the metal layer D. The polyimide resin layer B is formed substantially from a single layer. A single layer having a simple layer structure can be advantageously obtained industrially.

  Examples of the polyimide resin that forms the polyimide resin layer B include heat-resistant resins having an imide group in the structure such as polyamideimide, polybenzimidazole, polyimide ester, polyetherimide, polysiloxaneimide, including so-called polyimide resin. . In addition, a varnish of a commercially available polyimide precursor resin (also referred to as polyamic acid) can be used to form the polyimide resin layer B. For example, U-varnish-A (a polyamic acid varnish manufactured by Ube Industries, Ltd.) Product name), U-varnish-S (product name) and the like.

In addition, the polyimide resin layer B has a linear thermal expansion coefficient of 10 × 10 ⁻⁶ to 30 × 10 from the viewpoint of reducing the warpage of the laminate when the metal layer A or the metal layer D is removed by etching. ^-6 (1 / K), preferably 13 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K), more preferably 15 × 10 ⁻⁶ to 23 × 10 ⁻⁶ ( 1 / K). Such a polyimide resin is a non-thermoplastic polyimide resin.

As the polyimide resin constituting the polyimide resin layer B, a polyimide resin having a structural unit represented by the general formula (1) is preferable. In General Formula (1), Ar ₁ represents a tetravalent aromatic group represented by Formula (2) or Formula (3), and Ar ₃ represents a divalent group represented by Formula (4) or Formula (5). R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, and X and Y independently represent a single bond or a divalent hydrocarbon having 1 to 15 carbon atoms. A divalent group selected from the group, O, S, CO, SO ₂ or CONH, n independently represents an integer of 0 to 4, q represents the molar ratio of constituent units, 0.1 to 1 0.0, preferably in the range of 0.5 to 1.0.

  The structural unit may be present in the homopolymer or may be present as a structural unit of the copolymer. In the case of a copolymer having a plurality of structural units, it may exist as a block or may exist randomly.

Since a polyimide resin is generally produced by reacting a diamine and an acid anhydride, a specific example of the polyimide resin can be understood by explaining the diamine and the acid anhydride. In the above general formula (1), Ar ₃ can be referred to as a diamine residue, and Ar ₁ can be referred to as an acid anhydride residue. Therefore, a preferred polyimide resin will be described using a diamine and an acid anhydride. However, it is not limited to the polyimide resin obtained by this method.

  Examples of the diamine include 4,4′-diaminodiphenyl ether, 4,4′-diamino-2′-methoxy-benzanilide, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-amino). Phenoxy) benzene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diamino-2,2'-dimethylbiphenyl, 3,3'-dihydroxy-4,4'- Diaminobiphenyl, 4,4′-diaminobenzanilide, 2,2-bis- [4- (3-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- ( 3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-aminophenoxy)] biphenyl, bis [1 -(3-Aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) ) Phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, bis [4 -(4-Aminophenoxy)] benzophenone, bis [4- (3-aminophenoxy)] benzophenone, bis [4,4 '-(4-aminophenoxy)] benzanilide, bis [4,4'-(3-amino Phenoxy)] benzanilide, 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3-aminophenoxy) phenyl] fluorene, 2,2-bis- [4- (4-Aminophenoxy) phenyl] hexafluoropropane, 2,2-bis- [4- (3-aminophenoxy) phenyl] hexafluoropropane, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi -2,6-xylidine, 4,4'-methylene-2,6- Diethylaniline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3 '-Diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3 , 3-Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4 '' -Diamino-p-terphenyl, 3,3 ''-diamino-p-terphenyl, m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 1,4-bis (4-aminophenoxy) ) Zen, 1,3-bis (4-aminophenoxy) benzene, 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 and the like can be mentioned. Among these, preferable diamines particularly used for HDD suspension applications include 4,4′-diamino-2,2′-dimethylbiphenyl (m-TB), 4,4′-diamino-2′-methoxybenzanilide (MABA). ), 3,4'-diaminodiphenyl ether (DAPE34), 4,4'-diaminodiphenyl ether (DAPE44), 4,4'-bis (4-aminophenoxy) biphenyl (BAPB), 2,7'-bis (4- One or more diamines selected from aminophenoxy) naphthalene (NBOA), 1,3-bis (4-aminophenoxy) benzene (TPE-R), and 1,3-bis (3-aminophenoxy) benzene (APB) is there.

  Examples of the acid anhydride include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 2,2 ', 3,3'-, 2,3,3', 4'- or 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 2,3 ', 3,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3 ', 3,4'-diphenyl ether tetracarboxylic acid Preferred examples include dianhydrides and bis (2,3-dicarboxyphenyl) ether dianhydrides. Also 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-anthracene tetracarboxylic dianhydride, 2,2-bis (3,4-di Carboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic Acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6 -Tet Carboxylic 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 and the like can also be mentioned. Among these, the preferred acid anhydride used particularly for HDD suspension applications is one selected from pyromellitic anhydride (PMDA) and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA). There are the above acid anhydrides.

  About the said diamine and an acid anhydride, only 1 type may respectively be used and it can also be used in combination of 2 or more type. Thermal dimensional stability can be maintained by selecting and using the above diamine and acid anhydride. In addition, diamines and acid anhydrides other than those mentioned above can be used in combination. In this case, the proportion of diamines or acid anhydrides other than those mentioned above is 90 mol% or less, preferably 50 mol% or less. Control the thermal expansion, adhesiveness, glass transition point (Tg), etc. by selecting the type of diamine and acid anhydride, and the molar ratios when using two or more diamines or acid anhydrides. be able to.

  The synthesis of the polyamic acid, which is a precursor of the polyimide resin, can be performed by reacting approximately equimolar amounts of diamine and acid anhydride in a solvent. Examples of the solvent to be used include N, N-dimethylacetamide (DMAc), n-methylpyrrolidinone, 2-butanone, diglyme, xylene and the like, and these may be used alone or in combination of two or more. it can.

  The synthesized polyamic acid is used as a solution. Usually, it is advantageous to use as a reaction solvent solution, but if necessary, it can be concentrated, diluted or replaced with another organic solvent. Moreover, since polyamic acid is generally excellent in solvent solubility, it is advantageously used.

The polyimide resin layer B is composed of a low thermal expansion polyimide resin (hereinafter also referred to as polyimide resin B) having a linear thermal expansion coefficient of 10 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K). Such a low thermal expansion polyimide resin layer tends to have a low adhesive strength with the metal layer. Therefore, in order to secure the adhesive strength between the polyimide resin layer B and the metal layer A, the lamination method of the polyimide resin layer B to the metal layer A is performed by using a solution of polyamic acid (B ′) which is a precursor of the polyimide resin B. It is preferable to employ a method of applying directly to the metal layer A (hereinafter also referred to as a coating method). By this method, variation in adhesion between the metal layer A and the polyimide resin layer B can be suppressed, and the adhesive strength can be improved. Specifically, the adhesive strength between the metal layer A and the polyimide resin layer B is preferably 0.5 kN / m or more.

  The method for applying the polyamic acid (B ′) resin solution to the metal layer A is not particularly limited, and it can be applied by a coater such as a comma, a die, a knife, or a lip. As the metal layer A, a conductive metal layer having a thickness of 0.1 to 50 μm or a stainless steel layer having a thickness of 10 to 50 μm is suitable. The applied polyamic acid (B ′) becomes a polyimide resin layer B by drying and imidization.

  Further, the surface of the metal layer A in contact with the polyimide resin layer B may be subjected to an organic surface treatment agent such as a silane coupling agent treatment in order to further improve the adhesive strength.

  Although the polyimide resin layer B can improve the low thermal expansion characteristics as an insulating resin layer and the adhesion characteristics with the metal layer A by the above coating method, the metal layer D is formed on the other surface on the polyimide resin layer B side. In the case of laminating, it is practically impossible to apply the above coating method for improving the adhesiveness. Accordingly, the adhesive layer C is provided in order to ensure the adhesive strength with the metal layer D. The adhesive layer C will be described later. In order to obtain a polyimide resin layer B that has low thermal expansion characteristics and can effectively improve adhesive properties by a coating method, when the diamine component is 100 mol%, 4,4'-diamino-2,2 as the diamine It is preferable to use '-dimethylbiphenyl (m-TB) as an essential component, preferably 50 to 100 mol%, more preferably 60 to 90 mol%. When diamine other than m-TB is used in combination, 2,7'-bis (4-aminophenoxy) naphthalene (NBOA) and 1,3-bis (4-aminophenoxy) benzene (TPE-R) It is preferred to use at least one 10-30 mol%, more preferably at least one 10-30 mol% of MBOA and TPE-R, and 3,4'-diaminodiphenyl ether (DAPE34) and 4,4 It is preferred to use 1-20 mol% of at least one of '-diaminodiphenyl ether (DAPE44). Use of such a diamine in combination is preferable because it improves etching characteristics. Furthermore, when the acid anhydride component is 100 mol%, one kind selected from pyromellitic anhydride (PMDA) and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) as the acid anhydride. Or it is preferable to use 100 mol% of 2 types, More preferably, it is good to use 100 mol% of PMDA only. By using such a diamine and acid anhydride, not only can the low thermal expansion characteristics and etching characteristics be improved, but also sufficient adhesive strength with the metal layer A can be ensured, as well as high heat resistance and toughness. It is also possible to improve such properties. Properties such as toughness of the polyimide resin layer can be improved by controlling the weight average molecular weight of the polyamic acid obtained by reacting the monomer. Specifically, the weight average molecular weight (Mw) is controlled to be in the range of 150,000 to 800,000, preferably in the range of 200,000 to 800,000. In addition, the weight average molecular weight of a polyamic acid can obtain | require the value of the standard polystyrene conversion weight average molecular weight measured using the gel permeation chromatography (GPC). The toughness of the polyimide resin layer can be evaluated by measuring the tear propagation resistance using, for example, a light load tear tester manufactured by Toyo Seiki Co., Ltd.

  The adhesive layer C is obtained by mixing a mixed solution containing a polyamic acid (B ′), which is a precursor of the polyimide resin layer B, and a precursor resin (X ′) of the thermoplastic polyimide resin (X), into the polyimide resin layer B, the polyamic acid. (B ′) formed on the layer or metal layer D by coating, drying and imidization.

  The adhesive layer C has a function of improving the adhesiveness between the polyimide resin layer B and the metal layer D. A preferred example of a method for obtaining such an adhesive layer C includes a step of producing a metal-clad laminate in which a polyamic acid layer to be a polyimide resin layer B is laminated on the metal layer A (step a), and then There is a method having a step of applying and drying the mixed solution (step b) and a step of forming the polyimide resin layer B and the adhesive layer C (step C) by imidization reaction. Here, in step b, the polyamic acid layer is obtained by applying and drying a polyamic acid (B ′) solution.

  As the precursor resins (B ′) and (X ′), a precursor resin of a polyimide resin obtained from a known acid anhydride and diamine can be applied and can be produced by a known method. For example, it can be obtained by dissolving tetracarboxylic dianhydride and diamine in an organic solvent in approximately equimolar amounts and stirring at 0 to 100 ° C. for 30 minutes to 24 hours to cause a polymerization reaction. In the reaction, it is preferable to dissolve the reaction components so that the precursor resin of the obtained polyimide resin is 5 to 30% by weight, preferably 10 to 20% by weight in the organic solvent. As the organic solvent used in the polymerization reaction, it is preferable to use a polar one. Examples of the organic polar solvent include N, N-dimethylformamide, N, N-dimethylacetamide (DMAc), N-methyl. -2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfate, phenol, halogenated phenol, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme and the like. Two or more of these can be used in combination, and some aromatic hydrocarbons such as xylene and toluene can also be used.

  The precursor resins (B ′) and (X ′) are 25 to 85 parts by weight of the precursor resin (B ′), preferably 100 parts by weight of the precursor resins (B ′) and (X ′). Is used as a mixed solution mixed so as to be 30 to 70 parts by weight, more preferably 30 to 60 parts by weight. Usually, it is advantageous to use a mixed solution as each reaction solvent solution, but if necessary, it can be concentrated, diluted or replaced with another organic solvent. When the mixing ratio of the precursor resin (B ′) in the mixed solution is less than the above lower limit, the etching characteristics and the like of the obtained adhesive layer C tend to be similar to the characteristics of the thermoplastic polyimide resin (X). There is a possibility that a shape defect or the like occurs during etching of the resin layer. Moreover, when the mixing ratio of the precursor resin (B ′) exceeds the above upper limit, the adhesiveness of the adhesive layer C becomes poor. Here, the precursor resin (B ′) is the same as the polyamic acid (B ′) that gives the polyimide resin layer B, but it may not be completely the same, and some of the constituent monomers are different. However, the molecular weight and viscosity may be slightly different.

  The adhesive layer C is present so as to be laminated on one side of the polyimide resin layer B. The method for providing the adhesive layer C is not particularly limited. For example, the mixed solution is applied on the polyamic acid layer to be the polyimide resin layer B and dried to form two precursor resin layers, followed by heat treatment. The method of imidating by is mentioned. Moreover, although it may be provided on the metal layer D side, the former is simple in terms of process.

  The thickness of the adhesive layer C is 0.1 to 2.0 μm, preferably 0.5 to 1.5 μm, more preferably 0.8 to 1.2 μm. Furthermore, the value obtained by dividing the thickness of the polyimide resin layer B by the thickness of the adhesive layer C is preferably in the range of 1 to 40, and more preferably in the range of 2 to 30. By setting it as such a range, the adhesive strength of the adhesive layer is not lowered, and the etching shape becomes better.

  The mixed solution for forming the adhesive layer C contains the polyamic acid (B ′) and the precursor resin (X ′). By selecting the polyamic acid (B ′), the warp during the lamination of the metal layers is performed. In addition, the etching characteristics tend to be similar to that of the polyimide resin layer B, and the etching shape is improved. Further, the etching rate of the polyimide resin layer B is preferably 5 μm / min or more, and more preferably 10 μm / min or more. When the etching rate is less than 5 μm / min, it is difficult to obtain a good etching shape, and a higher etching rate value is preferable because a good etching shape is obtained. The details of the etching rate referred to in the present invention are based on the method described in the examples described later.

The precursor resin (X ′) of the thermoplastic polyimide resin (X) is preferably a polyimide precursor resin having a structural unit represented by the general formula (6). In General Formula (6), Ar ₄ represents a divalent aromatic group represented by Formula (7), Formula (8), or Formula (9), and Ar ₅ represents Formula (10) or Formula (11). R ₂ represents independently a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, and V and W independently represent a single bond or 1 to 15 carbon atoms. A divalent hydrocarbon group, a divalent group selected from O, S, CO, SO ₂ or CONH, m independently represents an integer of 0 to 4, p represents an existing mole of a structural unit; It is in the range of 1 to 1.0.

  The structural unit may be present in the homopolymer or may be present as a structural unit of the copolymer. In the case of a copolymer having a plurality of structural units, it may exist as a block or may exist randomly. Among the polyimide precursor resins having such a structural unit, a polyimide precursor resin that can be suitably used is a polyimide precursor resin that becomes a thermoplastic polyimide resin after imidization.

In the general formula (6), Ar ₄ can be referred to as a diamine residue, and Ar ₅ can be referred to as an acid dianhydride residue. Therefore, a preferable polyimide resin will be described using a diamine and an acid dianhydride. However, it is not limited to the polyimide precursor resin obtained by this method.

  Examples of the diamine include 4,4′-diaminodiphenyl ether, 2′-methoxy-4,4′-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-amino). Phenoxy) benzene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'- Diaminobiphenyl, 4,4′-diaminobenzanilide and the like can be mentioned. In addition, the diamine mentioned by description of the said polyimide resin can be mentioned.

  Examples of the acid dianhydride include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride 4,4′-oxydiphthalic anhydride. In addition, the acid dianhydride mentioned by description of the said polyimide resin can be mentioned.

  Each of diamine and acid dianhydride may be used alone or in combination of two or more. In addition, diamines and acid dianhydrides other than those described above can be used in combination.

  The thermoplastic polyimide resin (X) preferably has a glass transition temperature in the range of 200 to 320 ° C. By using such a polyimide resin, the adhesive strength with the metal layer is improved. Preferred diamines used to synthesize this polyimide resin include 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane and 2,2-bis [4- (4-aminophenoxy) phenyl. There is one or more diamines selected from propane, 1,3-bis- (3-aminophenoxy) benzene, paraphenylenediamine, 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether. Preferred acid anhydrides include pyromellitic anhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3', 4,4'-benzophenone tetra There is one or more acid anhydrides selected from carboxylic dianhydride (BTDA) and 3,3,4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA). About the said diamine and an acid anhydride, only 1 type may respectively be used and it can also be used in combination of 2 or more type.

  The metal layer D is provided on the adhesive layer C. As a method of providing the metal layer D, a method of superimposing a metal foil to be the metal layer D on the surface of the adhesive layer C and thermocompression bonding, or a metal thin film layer There is a method of forming. The lamination of the metal layer D in the metal-clad laminate of the present invention can obtain higher adhesive strength by applying thermocompression bonding. Therefore, the method of providing the metal layer D is preferably thermocompression bonding. Such an adhesive effect is more advantageously exhibited by controlling the thickness of the adhesive layer C. In addition, when the adhesive layer C is provided on the metal layer D, the laminate composed of the metal layer D / adhesive layer C is bonded to the polyimide resin layer B on the laminate composed of the metal layer / polyimide resin layer B. There is a method of thermocompression bonding so that the layer C is in contact.

  The metal layer A or the metal layer D may be subjected to a silane coupling agent treatment on the surface on which the polyimide resin layer is laminated. In particular, when thermocompression bonding is performed and the metal layer A or the metal layer D is a stainless steel layer, it is preferable to perform a silane coupling agent treatment. The silane coupling agent is preferably a silane coupling agent having a functional group such as an amino group or a mercapto group, more preferably a silane coupling agent having an amino group. Specific examples include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyl. Examples include trimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and the like. Among these, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyl It may be at least one selected from dimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine and N-phenyl-3-aminopropyltrimethoxysilane. In particular, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane are preferable.

  The silane coupling agent is used as a polar solvent solution. As the polar solvent, water or a polar organic solvent containing water is suitable. The polar organic solvent is not particularly limited as long as it is a polar liquid having an affinity for water. Examples of such a polar organic solvent include methanol, ethanol, propanol, isopropanol, acetone, tetrahydrofuran, dimethylformamide, dimethylacetamide and the like. The silane coupling agent solution has a concentration of 0.01 to 5% by weight, preferably 0.1 to 2.0% by weight, more preferably 0.5 to 1.0% by weight.

  The silane coupling agent treatment is not particularly limited as long as it is a method in which a solution of a polar solvent containing a silane coupling agent contacts, and a known method can be used. For example, a dipping method, a spray method, a brush coating method or a printing method can be used. The temperature may be 0 to 100 ° C., preferably 10 to 40 ° C. Moreover, as for immersion time, when applying the immersion method, it is effective to process for 10 second-1 hour, Preferably it is 30 second-15 minutes. Dry after treatment. The drying method is not particularly limited, and natural drying, spray drying with an air gun, oven drying, or the like can be used. The drying conditions depend on the type of polar solvent, but are 10 to 150 ° C. for 5 seconds to 60 minutes, preferably 25 to 150 ° C. for 10 seconds to 30 minutes, more preferably 30 to 120 ° C. for 1 minute to 10 minutes. It is.

  When the metal-clad laminate of the present invention is applied as an HDD suspension application, the total thickness of the polyimide resin layer B and the adhesive layer C is preferably in the range of 5 to 50 μm, more preferably 7 to 25 μm. Within the range, more preferably within the range of 8 to 12 μm. In addition, the metal layer A and the metal layer D are stainless steel layers having a thickness of 10 to 50 μm, the metal layer D is a conductive metal layer having a thickness of 0.01 to 50 μm, or the metal layer A is 0 It is a conductive metal layer having a thickness of 1 to 50 μm, and the metal layer D is preferably a stainless steel layer having a thickness of 10 to 50 μm. Further, when the conductive metal layer is formed as a fine flying lead having a circuit width of 40 μm or less, for example, the layer of the metal-clad laminate is used in terms of in-plane adhesion variation or chemical resistance. The configuration is preferably conductor metal layer / polyimide resin layer / adhesive layer / stainless steel layer. In addition, the range of the material and thickness of each layer is as having mentioned above.

  Next, a method for providing the metal layer D and a method for producing the metal-clad laminate will be described in detail. A preferred example of the method for producing a metal-clad laminate includes a step of producing a metal-clad laminate in which a polyamic acid layer to be a polyimide resin layer B is laminated on the metal layer A (step a), and then the above mixed solution The step of applying and drying (step b), the step of forming the polyimide resin layer B and the adhesive layer C by imidization reaction (step C), and forming the metal layer D on the adhesive layer C There is a method having a step (step d).

  Step d is a step of providing a metal layer D on the adhesive layer C formed in step c. As a method of providing the metal layer D, there is a method of overlaying a metal foil on the surface of the adhesive layer C and thermocompression bonding (step d1), or a method of forming a metal thin film (step d2).

  In the step d1, a method for thermocompression bonding is not particularly limited, and a known method can be appropriately employed. Examples of the method of laminating the metal foil include a normal hydro press, a vacuum type hydro press, an autoclave pressurizing vacuum press, and a continuous thermal laminator. Among the methods of laminating metal foils, a vacuum hydropress and a continuous thermal laminator are used from the viewpoint that sufficient pressing pressure is obtained, residual volatiles can be easily removed, and oxidation of the metal foil can be prevented. It is preferable to use it.

  Moreover, it is preferable to press the metal foil used as the metal layer D, heating in the range of 150-450 degreeC for thermocompression bonding. More preferably, it exists in the range of 150-400 degreeC. Furthermore, it is preferably in the range of 150 to 380 ° C. From another point of view, the temperature is preferably equal to or higher than the glass transition temperature of the polyimide resin layer or the modified imidized layer. The press pressure is usually about 1 to 50 MPa, although it depends on the type of press equipment used.

  As metal foil, iron foil, nickel foil, beryllium foil, aluminum foil, zinc foil, indium foil, silver foil, gold foil, tin foil, zirconium foil, stainless steel foil, tantalum foil, titanium foil, copper foil, lead foil, magnesium foil , Manganese foils and alloy foils thereof. Among these, stainless steel foil, copper foil or copper alloy foil is suitable. The thickness is preferably in the range of 0.1 to 50 μm.

In step d2, the metal thin film layer is formed by a vapor deposition method. The vapor deposition method is not particularly limited. For example, a vacuum vapor deposition method, a sputtering method, an electron beam vapor deposition method, an ion plating method, or the like can be used, and the sputtering method is particularly preferable. This sputtering method includes various methods such as DC sputtering, RF sputtering, DC magnetron sputtering, RF magnetron sputtering, EC sputtering, and laser beam sputtering, but is not particularly limited and can be appropriately employed. Regarding the conditions for forming the metal thin film layer by sputtering, for example, argon gas is used as the sputtering gas, and the pressure is preferably 1 × 10 ^{−2 to 1} Pa, more preferably 5 × 10 ^{−2 to} 5 × 10 ⁻¹ Pa. The sputtering power density is preferably 1 to 100 Wcm ⁻² , more preferably 1 to 50 Wcm ⁻² . In this case, the metal layer comprising the metal thin film layer can be made sufficiently thin. A thick conductive metal layer may be appropriately formed on the thin metal film layer thus formed by electroless plating or electrolytic plating. That is, the thickness can be 0.01 to 50 μm, preferably 0.05 to 5 μm, more preferably 0.1 to 1.0 μm.

  Examples of metals suitable for the metal thin film layer provided by vapor deposition include copper, nickel, chromium, and alloys thereof. The vapor deposition method has an advantage that a metal thin film can be formed, but is not suitable for forming a thick film. Therefore, when the metal thin film layer is thickened to lower the electrical resistance or increase the strength, a relatively thick copper thin film layer may be provided thereon. That is, a metal thin film having a thickness of about 0.001 to 0.5 μm is formed by vapor deposition, and a plating layer may be provided when the thickness is more than that. As the vapor deposition method, a known method such as sputtering or CVD can be employed.

  Formation of the metal thin film by the vapor deposition method preferably uses copper as the thin film layer. Under the present circumstances, the base metal thin film layer which improves adhesiveness more may be provided in a surface treatment polyimide resin layer, and a copper thin film layer may be provided on it. Examples of the base metal thin film layer include nickel, chromium, and an alloy layer thereof. When the base metal thin film layer is provided, the thickness is 1/2 or less, preferably 1/5 or less of the thickness of the copper thin film layer, and is preferably about 1 to 50 nm. This underlying metal thin film layer is also preferably formed by sputtering.

  The copper used here may be alloy copper partially containing other metals. The copper or copper alloy formed by the sputtering method preferably has a copper content of 90% by mass or more, particularly preferably 95% by mass or more. Examples of the metal that copper can contain include chromium, zirconium, nickel, silicon, zinc, and beryllium. Moreover, the copper alloy in which these metals contain 2 or more types may be sufficient.

  The thickness of the metal thin film layer formed in step d2 is preferably in the range of 0.01 to 1.0 μm, preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.5 μm. . When the thin film layer is further thickened, it may be thickened by electroless plating or electrolytic plating. The metal layer formed in this way can be formed into a circuit by a subtractive method or a semi-additive method.

  The metal-clad laminate of the present invention is suitable for double-sided FPC, HDD suspension applications and the like. The metal-clad laminate for HDD suspension of the present invention is the metal-clad laminate of the present invention, wherein one metal layer is made of a stainless steel layer and the other layer is made of a conductive metal layer such as copper.

  The HDD suspension of the present invention can be obtained by processing the metal-clad laminate. As a preferable processing method, there is a method called a TSA method in which a laminate of stainless steel foil-polyimide resin-copper foil is processed into a predetermined shape by etching to form a wiring integrated suspension.

  EXAMPLES Hereinafter, although an Example demonstrates this invention based on an Example, this invention is not limited at all by these Examples. In the examples of the present invention, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of adhesive strength]
The adhesion strength between the metal layer and the polyimide resin layer is as follows. For a metal-clad laminate, a test piece for measuring 1/8 inch wiring width is prepared by circuit processing, and the metal layer side is attached to the fixed plate. Then, using a tensile tester (Strograph-M1 manufactured by Toyo Seiki Co., Ltd.), the metal foil was peeled in the 90 ° direction and the strength was measured.
Moreover, it measured similarly about the adhesive strength of the metal layer and polyimide resin layer through an adhesive layer.
The peel strength between the support copper foil and the ultrathin copper foil was fixed to the stainless steel plate with double-sided tape using a Tensilon tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a double-sided tape. The support copper foil was peeled off at a rate of 50 mm / min in the 90 ° direction.

[Measurement of dimensional change rate]
For measuring the dimensional change rate, first, a 300 mm square metal-clad laminate is used, and a test piece 1 is formed by exposing and developing a dry film resist with a position measurement target at 200 mm intervals. After measuring the dimensions before etching (normal state) in an atmosphere with a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%, the copper other than the target of the test piece 1 is etched (liquid temperature 40 # C or less, within 10 minutes) ) To form the test piece 2. After being left for 24 ± 4 hours in an atmosphere having a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%, the dimensions after etching are measured in the same manner as in the normal state. The dimensional change rate with respect to the normal state at each of the three positions in the vertical direction and the horizontal direction is calculated, and the average value of each is taken as the dimensional change rate after etching.

[Measurement of linear thermal expansion coefficient]
The linear thermal expansion coefficient was measured using a thermomechanical analyzer (manufactured by Seiko Instruments Inc.) at a rate of 20 ° C./min up to 255 ° C., held at that temperature for 10 minutes, and then kept constant at 5 ° C./min. Cooled at speed. The average thermal expansion coefficient (linear thermal expansion coefficient) from 240 ° C. to 100 ° C. during cooling was calculated.

[Measurement of glass transition temperature]
Using a viscoelasticity analyzer (RSA-II, manufactured by Rheometric Science Effy Co., Ltd.), using a 10 mm wide sample, raising the temperature from room temperature to 400 ° C. at a rate of 10 ° C./min while applying 1 Hz vibration Of the loss tangent (Tanδ).

  The thickness of the adhesive layer was measured by setting the transmission mode using a scanning transmission electron microscope (manufactured by Hitachi High-Technologies Corporation), observing the cross section of the sample, and confirming the thickness of the adhesive layer.

[Measurement of etching rate]
The polyimide film was immersed in an etching solution heated to 80 ° C. (ethylene diamine 11.0 wt%, ethylene glycol 22.0 wt%, potassium hydroxide 33.5 wt%), and the time when the polyimide was completely dissolved was measured. It was determined by dividing the film thickness by the measurement time.

[Measurement of polyimide etching shape]
First, a 100 mm square metal-clad laminate was used, the copper foil side was etched, and a via having a diameter of 100 μm was formed as a test piece. Thereafter, using the copper foil as an etching mask, the test piece was immersed in an etching solution heated to 80 ° C. (ethylene diamine 11.0 wt%, ethylene glycol 22.0 wt%, potassium hydroxide 33.5 wt%) for 10 to 60 seconds. After immersion, the cross section of the test piece was polished, and the side etching shape of polyimide was observed.
In addition, in the insulating resin layer after etching, the level where the boundary between the polyimide resin layer and the adhesive layer is not confirmed is “excellent”, and the level where the boundary between the polyimide resin layer and the adhesive layer is slightly confirmed Although it was judged as “good”, the boundary between the polyimide resin layer and the adhesive layer could be confirmed, but those having no unevenness were evaluated as “good”. Moreover, the thing with an unevenness | corrugation confirmed in the boundary of a polyimide resin layer and an adhesive layer was evaluated as "impossible."

  Next, the present invention will be specifically described based on the following examples. Of course, the present invention is not limited to this.

In addition, the symbol used for the present Example is as follows.
m-TB: 4,4'-Diamino-2,2'-dimethylbiphenyl
TPE-R: 1,3-bis (4-aminophenoxy) benzene
PMDA: pyromellitic anhydride
NBOA: 2,7'-bis (4-aminophenoxy) naphthalene
DAPE34: 3,4'-diaminodiphenyl ether
DAPE44: 4,4'-diaminodiphenyl ether
DANPG: 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane
BTDA: 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride
APB: 1,3-bis (3-aminophenoxy) benzene
DMAc: N, N-dimethylacetamide

Synthesis example 1
In a 500 ml separable flask, 15.77 g m-TB (0.074 mol) and 2.41 g TPE-R (0.008 mol) were dissolved in 264 g DMAc with stirring. Next, 17.82 g PMDA (0.082 mol) was added to the solution under a nitrogen stream. Thereafter, the polymerization reaction was continued by stirring for 4 hours to obtain a viscous polyamic acid resin solution s1. The viscosity of the polyamic acid resin solution s1 at 25 ° C. was 29,200 cP. The viscosity was measured at 25 ° C. with a cone plate viscometer (manufactured by Tokimec Co., Ltd.) equipped with a constant temperature water bath. Moreover, the weight average molecular weight (Mw) of the polyamic acid in the resin solution s1 was 210,000.
The obtained polyamic acid resin solution s1 was applied onto a substrate, dried at 130 ° C. for 5 minutes, then heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide resin layer was obtained, and this resin layer was peeled from the stainless steel base material to obtain a polyimide film S1 having a thickness of 12 μm. The linear thermal expansion coefficient of this film was 12 × 10 ⁻⁶ / K. The etching rate was 25 μm / min.

Synthesis example 2
In a 500 ml separable flask, 12.76 g m-TB (0.06 mol) and 5.49 g NBOA (0.024 mol) were dissolved in 268 g DMAc with stirring. Next, 18.31 g of PMDA (0.084 mol) was added to the solution under a nitrogen stream. Thereafter, stirring was continued for 4 hours to carry out a polymerization reaction, thereby obtaining a viscous polyamide acid resin solution s2. The viscosity of the polyamic acid resin solution s2 at 25 ° C. was 30,000 cP. Moreover, the weight average molecular weight (Mw) in the resin solution s2 was 180,000.
The obtained polyamic acid resin solution s2 was applied onto a substrate, dried at 130 ° C. for 5 minutes, then heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide resin layer was obtained, and this resin layer was peeled off from the stainless steel substrate to obtain a polyimide film S2 having a thickness of 12 μm. The linear thermal expansion coefficient of this film was 16 × 10 ⁻⁶ / K. The etching rate was 19 μm / min.

Synthesis example 3
In a 500 ml separable flask, with stirring, 12.08 g m-TB (0.057 mol), 4.75 g TPE-R (0.016 mol) and 1.63 g DAPE34 (0.008 mol) Was dissolved in 264 g of DMAc. The solution was then added 17.55 g PMDA (0.08 mol) under a stream of nitrogen. Thereafter, the polymerization reaction was continued by stirring for 4 hours to obtain a viscous polyamide acid resin solution s3. The viscosity of the polyamic acid resin solution s3 at 25 ° C. was 13,200 cP. Moreover, the weight average molecular weight (Mw) of the polyamic acid in the resin solution s3 was 219,000.
The obtained polyamic acid resin solution s3 was applied onto a substrate, dried at 130 ° C. for 5 minutes, then heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide resin layer was obtained, and this resin layer was peeled from the stainless steel base material to obtain a polyimide film S3 having a thickness of 12 μm. The linear thermal expansion coefficient of this film was 22 × 10 ⁻⁶ / K. The etching rate was 23 μm / min.

Synthesis example 4
In a 500 ml separable flask, with stirring, 12.08 g m-TB (0.057 mol), 4.75 g TPE-R (0.016 mol) and 1.63 g DAPE44 (0.008 mol) Was dissolved in 264 g of DMAc. The solution was then added 17.55 g PMDA (0.08 mol) under a stream of nitrogen. Thereafter, stirring was continued for 4 hours to carry out a polymerization reaction, thereby obtaining a viscous polyamide acid resin solution s4. The viscosity of the polyamic acid resin solution s4 at 25 ° C. was 19,200 cP. Moreover, the weight average molecular weight (Mw) of the polyamic acid in the resin solution s4 was 235,000.
The obtained polyamic acid resin solution s4 was applied onto a substrate, dried at 130 ° C. for 5 minutes, then heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide resin layer was obtained, and this resin layer was peeled off from the stainless steel substrate to obtain a polyimide film S4 having a thickness of 12 μm. The linear thermal expansion coefficient of this film was 17 × 10 ⁻⁶ / K. The etching rate was 23 μm / min.

Synthesis example 5
264 g of 12.08 g m-TB (0.057 mol), 4.75 g NBOA (0.016 mol) and 1.63 g DAPE34 (0.008 mol) with stirring in a 500 ml separable flask. In DMAc. The solution was then added 17.55 g PMDA (0.08 mol) under a stream of nitrogen. Thereafter, the polymerization reaction was continued by stirring for 4 hours to obtain a viscous polyamide acid resin solution s5. The viscosity of the polyamic acid resin solution s5 at 25 ° C. was 3,400 cP. Further, the weight average molecular weight (Mw) of the polyamic acid in the resin solution s5 was 150,000.
The obtained polyamic acid resin solution s5 was applied onto a substrate, dried at 130 ° C. for 5 minutes, then heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide resin layer was obtained, and this resin layer was peeled off from the stainless steel substrate to obtain a polyimide film S5 having a thickness of 12 μm. The linear thermal expansion coefficient of this film was 19 × 10 ⁻⁶ / K. The etching rate was 17 μm / min.

Synthesis Example 6
In a 500 ml separable flask, 30.3 g of 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane (DANPG) (0.057 mol) was dissolved in 352 g of DMAc with stirring. . The solution was then added with 9.3 g PMDA (0.04 mol) and 20.5 g BTDA (0.06 mol) under a stream of nitrogen. Then, the polymerization reaction was continued for about 3 hours to obtain a viscous polyamic acid resin solution s6.
The obtained polyamic acid resin solution s6 was applied onto a substrate, dried at 130 ° C. for 5 minutes, then heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide resin layer was obtained, and this resin layer was peeled off from the stainless steel substrate to obtain a polyimide film S6 having a thickness of 12 μm. The linear thermal expansion coefficient of this film was 35 × 10 ⁻⁶ / K.

Synthesis example 7
In a 500 ml separable flask, 29.5 g APB (0.1 mol) was dissolved in 367 g DMAc with stirring. The solution was then charged with 9.1 g PMDA (0.04 mol) and 20.2 g BTDA (0.06 mol) in a stream of nitrogen. Thereafter, stirring was continued for about 3 hours to carry out a polymerization reaction to obtain a viscous polyimide resin precursor solution s7.
The obtained precursor solution s7 is coated on a stainless steel substrate, dried at 130 ° C. for 5 minutes, heated to 360 ° C. over 15 minutes to complete imidization, and polyimide laminated on the stainless steel substrate A resin layer was obtained, and this resin layer was peeled off from the stainless steel substrate to obtain a polyimide film S7 having a thickness of 12 μm. The glass transition temperature of this film was 218 ° C. The etching rate was 8 μm / min.

Synthesis example 8
A silane coupling agent solution was prepared by mixing 5 g of 3-aminopropyltrimethoxysilane, 500 g of methanol and 2.5 g of water and stirring for 2 hours. After pre-washing stainless steel foil 1 (SUS304 H-TA, manufactured by Nippon Steel Corp., thickness 20 μm) for 30 seconds in a silane coupling agent solution (liquid temperature of about 20 ° C.), the steel foil was once pulled up into the atmosphere to remove excess The liquid was dropped. Then, it was dried by blowing compressed air for about 15 seconds. Then, heat processing were performed for 30 minutes at 110 degreeC, and the stainless steel foil 2 of a silane coupling agent process was obtained.

Example 1
The weight ratio of the precursor component a1 in the polyamic acid resin solution s1 obtained in Synthesis Example 1 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is set to a ratio of 70:30. After mixing the resin solution s1 and the precursor solution s7, DMAc was added and diluted to prepare a mixed solution p1 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
The resin solution s1 was applied to the stainless steel foil 1 using an applicator and dried at 130 ° C. for 5 minutes to form a polyamic acid layer so that the thickness after curing was 12 μm. On the polyamic acid layer, the above mixed solution p1 is applied with a wet thickness of about 30 μm, dried at 130 ° C. for 2 minutes, and then heated to 360 ° C. over 15 minutes to complete imidization, and the stainless steel foil layer. A laminate L1 composed of a polyimide resin layer and an adhesive layer was produced. The thickness of the adhesive layer of this laminate was 1.0 μm.
Electrolytic copper foil 1 (manufactured by Mitsui Kinzoku Co., Ltd., NS-VLP foil, copper foil thickness 9 μm) is superimposed on the surface of the adhesive layer of the obtained laminate, and is 20 MPa and temperature 370 by a high-performance high-temperature vacuum press. The metal-clad laminate 1 composed of a stainless steel layer, an insulating resin layer, and a copper foil layer was obtained by thermocompression bonding under the conditions of ° C and a press time of 1 minute. The adhesive strength on the stainless steel side and the copper foil side and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 1 was excellent in adhesive strength and dimensional stability, and the shape of the insulating resin layer of the etching solution was also very good. The adhesive strength of 0.5 kN / m or more was regarded as no problem.

Example 2
The weight ratio of the precursor component a1 in the polyamic acid resin solution s1 obtained in Synthesis Example 1 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 50:50. After mixing the resin solution s1 and the precursor solution s7, DMAc was added to dilute to prepare a mixed solution p2 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
A metal composed of a stainless steel foil layer, a polyimide resin layer, an adhesive layer and a copper foil layer in the same manner as in Example 1, except that the above mixed solution p2 was used instead of the mixed solution p1 in Example 1. A stretched laminate 2 was obtained. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 2 was excellent in adhesive strength, and the shape of the insulating resin layer after etching was also good.

Example 3
The weight ratio of the precursor component a1 in the polyamic acid resin solution s1 obtained in Synthesis Example 1 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 30:70. After mixing the resin solution s1 and the precursor solution s7, DMAc was added to dilute to prepare a mixed solution p3 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
A metal composed of a stainless steel foil layer, a polyimide resin layer, an adhesive layer and a copper foil layer in the same manner as in Example 1 except that the above mixed solution p3 was used instead of the mixed solution p1 in Example 1. A stretched laminate 3 was obtained. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 3 was excellent in adhesive strength, and there was no problem with the shape of the insulating resin layer after etching.

Example 4
The weight ratio of the precursor component a2 in the resin solution s2 of the polyamic acid obtained in Synthesis Example 2 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 50:50. After the resin solution s2 and the precursor solution s7 were mixed, DMAc was added and diluted to prepare a mixed solution p4 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
The same procedure as in Example 1 was performed except that the above mixed solution p4 was used instead of the mixed solution p1 in Example 1, and the resin solution s2 was used instead of the resin solution s1 in Example 1. A metal-clad laminate 4 composed of a stainless steel foil layer, a polyimide resin layer, an adhesive layer and a copper foil layer was obtained. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 4 was excellent in adhesive strength, and the shape of the insulating resin layer of the etching solution was also good.

Example 5
The weight ratio of the precursor component a3 in the polyamic acid resin solution s3 obtained in Synthesis Example 3 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 50:50. After mixing the resin solution s3 and the precursor solution s7, DMAc was added to dilute to prepare a mixed solution p5 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
The same procedure as in Example 1 was performed except that the mixed solution p5 was used instead of the mixed solution p1 in Example 1, and the resin solution s3 was used instead of the resin solution s1 in Example 1. A metal-clad laminate 5 composed of a stainless steel foil layer, a polyimide resin layer, an adhesive layer and a copper foil layer was obtained. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 5 was excellent in adhesive strength, and the shape of the insulating resin layer of the etching solution was also good.

Example 6
The weight ratio of the precursor component a4 in the polyamic acid resin solution s4 obtained in Synthesis Example 4 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 50:50. After mixing the resin solution s4 and the precursor solution s7, DMAc was added to dilute to prepare a mixed solution p6 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
Except that the mixed solution p6 was used instead of the mixed solution p1 in Example 1, and that the resin solution s4 was used instead of the resin solution s1 in Example 1, the same procedure as in Example 1 was performed. A metal-clad laminate 6 composed of a stainless steel foil layer, a polyimide resin layer, an adhesive layer and a copper foil layer was obtained. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 6 was excellent in adhesive strength, and the shape of the insulating resin layer of the etching solution was also good.

Example 7
The weight ratio of the precursor component a5 in the polyamic acid resin solution s5 obtained in Synthesis Example 5 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 50:50. After the resin solution s5 and the precursor solution s7 were mixed, DMAc was added for dilution to prepare a mixed solution p7 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
The same procedure as in Example 1 was performed except that the mixed solution p7 was used instead of the mixed solution p1 in Example 1, and the resin solution s5 was used instead of the resin solution s1 in Example 1. A metal-clad laminate 7 composed of a stainless steel foil layer, a polyimide resin layer, an adhesive layer and a copper foil layer was obtained. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 7 was excellent in adhesive strength, and the shape of the insulating resin layer of the etching solution was also good.

Example 8
The mixed solution p2 used in Example 2 was prepared.
The resin solution s1 was applied to the stainless steel foil 2 using an applicator and dried at 130 ° C. for 5 minutes to form a polyamic acid layer so that the thickness after curing was 12 μm. On this polyamic acid layer, the above mixed solution p2 is applied with a wet thickness of about 30 μm, dried at 130 ° C. for 2 minutes, and then heated to 360 ° C. over 15 minutes to complete imidization, and the stainless steel foil layer. A laminate L8 composed of a polyimide resin layer and an adhesive layer was produced. The thickness of the adhesive layer of this laminate was 1.0 μm.
It was set in an RF magnetron sputtering apparatus (ANELVA; SPF-332HS) so that a metal raw material was formed on the surface of the adhesive layer of the obtained laminate, and the inside of the tank was depressurized to 3 × 10 ⁻⁴ Pa. Thereafter, argon gas was introduced to make the degree of vacuum 2 × 10 ⁻¹ Pa, and plasma was generated by an RF power source. A nickel: chromium alloy layer [ratio 8: 2, 99.9 wt%, hereinafter referred to as a nichrome layer (first sputtering layer)] was formed on the polyimide film by this plasma so as to have a film thickness of 30 nm. After forming the nichrome layer, in the same atmosphere, 0.2 μm of copper (99.99 wt%) was further formed on the nichrome layer by sputtering to obtain a second sputtering layer.
Next, a copper plating layer having a thickness of 8 μm was formed in an electrolytic plating bath using the sputtered film (second sputtering layer) as an electrode. As an electrolytic plating bath, a copper sulfate bath (copper sulfate 100 g / L, sulfuric acid 220 g / L, chlorine 40 mg / L, anode is phosphorus-containing copper) is used, and a plating film is formed at a current density of 2.0 A / dm ² . did. After plating, it was washed with sufficient distilled water and dried to produce a metal-clad laminate 8. The adhesive strength between the insulating resin layer and the metal layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 8 was excellent in adhesive strength, and the shape of the insulating resin layer after etching was also good.

Example 9
The mixed solution p2 used in Example 2 was prepared.
The mixed solution p2 was used instead of the mixed solution p1 in Example 1, the electrolytic copper foil 1 was used in place of the stainless steel foil 1 in Example 1, and the electrolytic copper foil 1 in Example 1 A metal-clad laminate 9 composed of a copper foil layer, an insulating resin layer, and a stainless steel foil layer was obtained in the same manner as in Example 1 except that the stainless steel foil 1 was used instead of. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 9 was excellent in adhesive strength, and the shape of the insulating resin layer of the etching solution was also good.

Example 10
The mixed solution p2 used in Example 2 was prepared.
Resin solution s1 is made of ultrathin copper foil 1 with support copper foil (manufactured by Nihon Electrolysis Co., Ltd., YSNAP-3B, support copper foil thickness 18 μm, ultrathin copper foil thickness 1 μm, inorganic release layer) It was applied using an applicator and dried at 130 ° C. for 5 minutes to form a polyamic acid layer so that the thickness after curing was 12 μm. On this polyamic acid layer, the above mixed solution p2 is applied with a wet thickness of about 30 μm, dried at 130 ° C. for 2 minutes, and then heated to 360 ° C. over 15 minutes to complete imidization, and a copper foil layer A laminate L10 composed of a polyimide resin layer and an adhesive layer was produced. The thickness of the adhesive layer of this laminate was 1.0 μm.
A stainless steel foil 2 is superimposed on the surface of the adhesive layer of the obtained laminate, and a metal-clad laminate 10 composed of a copper foil layer, an insulating resin layer and a stainless steel foil layer is obtained in the same manner as in Example 1. It was. The adhesive strength of the stainless steel side and the copper foil layer and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 1. The obtained metal-clad laminate 10 was excellent in adhesive strength, and the shape of the insulating resin layer of the etching solution was also good.

Comparative Example 1
The polyimide film S1 obtained in Synthesis Example 1 was overlaid with the electrolytic copper foil 1, and was pressed with a high-performance high-temperature vacuum press machine at 370 ° C., 20 MPa for 1 minute to obtain a metal-clad laminate 11. . The adhesive strength between the insulating resin layer and the copper foil was less than 0.1 kN / m.

Comparative Example 2
The polyimide film S2 obtained in Synthesis Example 2 was overlaid with the electrolytic copper foil 1 and pressed with a high-performance high-temperature vacuum press machine at 370 ° C., 20 MPa for 1 minute to obtain a metal-clad laminate 12. . The adhesive strength between the insulating resin layer and the copper foil was less than 0.1 kN / m.

Comparative Example 3
The polyimide film S3 obtained in Synthesis Example 3 was overlaid with the electrolytic copper foil 1, and pressed with a high-performance high-temperature vacuum press machine at 370 ° C., 20 MPa, for 1 minute to obtain a metal-clad laminate 13. . The adhesive strength between the insulating resin layer and the copper foil was less than 0.1 kN / m.

Comparative Example 4
The polyimide film S4 obtained in Synthesis Example 4 was overlaid with the electrolytic copper foil 1 and pressed with a high-performance high-temperature vacuum press machine at 370 ° C., 20 MPa for 1 minute to obtain a metal-clad laminate 14. . The adhesive strength between the insulating resin layer and the copper foil was less than 0.1 kN / m.

Comparative Example 5
The electrolytic copper foil 1 is superposed on the polyimide resin film S5 obtained in Synthesis Example 5, and pressed with a high-performance high-temperature vacuum press at 370 ° C., 20 MPa for 1 minute to obtain a metal-clad laminate 15. It was. The adhesive strength between the insulating resin layer and the copper foil was less than 0.1 kN / m.

Comparative Example 6
The resin solution s6 is applied to the stainless steel foil 1 using an applicator, dried at 130 ° C. for 5 minutes, and then heated to 360 ° C. over 15 minutes to complete imidization. 1 were stacked and pressed with a high-performance high-temperature vacuum press machine at 370 ° C., 20 MPa, and 1 minute to obtain a metal-clad laminate 16. The obtained laminate had no problem in the adhesive strength, but the dimensional change rate was −0.80%, and the laminate was warped.

Comparative Example 7
Instead of applying the mixed solution p1 in Example 1 with a wet thickness of about 30 μm, the polyimide resin precursor solution s7 obtained in Synthesis Example 7 was applied so that the thickness after curing was 1.0 μm. Obtained a metal-clad laminate 17 in the same manner as in Example 1. The obtained laminate had no problem in adhesive strength and dimensional stability, but unevenness occurred in the shape of the insulating resin layer after etching.

Comparative Example 8
The weight ratio of the precursor component a1 in the polyamic acid resin solution s1 obtained in Synthesis Example 1 and the precursor component b7 in the precursor solution s7 obtained in Synthesis Example 7 is 20:80. After mixing the resin solution s1 and the precursor solution s7, DMAc was added to dilute to prepare a mixed solution p18 in which the solid content concentration as the precursor component was adjusted to 12% by weight.
Instead of applying the mixed solution p1 in Example 1 with a wet thickness of about 30 μm, the same procedure as in Example 1 was performed except that the mixed solution p18 was applied so that the thickness after curing was 1.0 μm. As a result, a metal-clad laminate 18 was obtained. The obtained laminate had no problem in adhesive strength and dimensional stability, but unevenness occurred in the shape of the insulating resin layer after etching.

The above results are summarized in Table 1. In Table 1, the resin layer (μm) indicates the total thickness (μm) of the polyimide resin layer and the adhesive layer of the obtained metal-clad laminate, and the adhesive layer (μm) is the adhesive layer or Indicates the thickness (μm) of the adhesive layer, CTE (ppm / K) indicates the linear thermal expansion coefficient (× 10 ⁻⁶ / K) of the polyimide resin layer, and the A side of the adhesive strength is the metal layer A Indicates the adhesive strength of the polyimide resin layer, the D side of the adhesive strength indicates the adhesive strength between the metal layer D and the adhesive layer, and the dimensional change rate (%) indicates the dimensional change rate (%) after etching. The shape indicates the shape of the insulating resin layer after etching. In the column of metal layers A and D, SUS1 is stainless steel foil 1, SUS2 is stainless steel foil 2, copper foil is electrolytic copper foil 1, and s + p is sputter + plating.

Claims (7)

A metal-clad laminate composed of a metal layer A, a polyimide resin layer B, an adhesive layer C, and a metal layer D in this order. The polyimide resin layer B is a single layer having a thickness of 5 to 50 μm, and has a linear thermal expansion coefficient. Is 10 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), and the adhesive layer C has a thickness of 0.1 to 2.0 μm, and is a polyimide resin precursor constituting the polyimide resin layer B. It is formed by drying and imidizing a mixed solution containing a precursor resin (X ′) of a polyamic acid (B ′) and a thermoplastic polyimide resin (X), and the mixed solution is a precursor resin (B A metal-clad laminate comprising 25 to 85 parts by weight of the precursor resin (B ′) with respect to a total of 100 parts by weight of ') and (X').   2. The metal-clad laminate according to claim 1, wherein the thermoplastic polyimide resin (X) has a glass transition temperature in the range of 200 to 320 ° C. 3.   3. The metal-clad laminate according to claim 1, wherein the total thickness of the polyimide resin layer B and the adhesive layer C is in the range of 5 to 50 μm.   The metal-clad laminate according to any one of claims 1 to 3, wherein the metal layer A is a conductive metal layer having a thickness of 0.1 to 50 µm, and the metal layer D is a stainless steel layer having a thickness of 10 to 50 µm.   The metal-clad laminate according to any one of claims 1 to 3, wherein the metal layer A is a stainless steel layer having a thickness of 10 to 50 µm, and the metal layer D is a conductive metal layer having a thickness of 0.01 to 50 µm.   A metal-clad laminate for an HDD suspension, comprising the metal-clad laminate according to claim 4 or 5.   An HDD suspension obtained by processing the metal-clad laminate for an HDD suspension according to claim 6.