JP5009756B2 - Method for producing polyimide resin layer having adhesive layer and method for producing metal tension plate - Google Patents

Description

  The present invention relates to a method for producing a polyimide resin layer having an adhesive layer with improved adhesion and a method for producing a metal-clad laminate in which a metal layer is laminated on the surface thereof, and more particularly, suitable for printed wiring boards. The present invention relates to a method for producing a metal-clad laminate.

  In an electronic circuit of an electronic device, a printed wiring board obtained by processing a laminated board made of an insulating material and a conductive material is used. A printed wiring board is formed by fixing a conductive pattern based on electrical design on the surface (and inside) of an insulating substrate with a conductive material. Depending on the type of insulating resin used as the base material, a plate-shaped rigid printed wiring is used. It is roughly divided into a board and a flexible printed wiring board which is rich in flexibility. The flexible printed wiring board is characterized by having flexibility, and is a necessary part for connection in a movable part that constantly bends. In addition, since the flexible printed wiring board can be stored in a bent state in an electronic device, it is also used as a space-saving wiring material. In a flexible substrate as a material for a flexible printed wiring board, polyimide ester or polyimide resin is often used as an insulating resin as a base material, but the amount of heat-resistant polyimide resin is overwhelmingly large. On the other hand, copper foil is generally used as the conductive material from the viewpoint of conductivity.

  The flexible substrate includes a three-layer flexible substrate and a two-layer flexible substrate because of its structure, and is a metal-clad laminate having a conductive material layer such as a copper foil layer and an insulating material layer such as a polyimide resin layer. A three-layer flexible substrate is made by bonding a base film such as polyimide and a copper foil with an adhesive such as an epoxy resin or an acrylic resin to form a base film layer (main layer of an insulating resin layer), an adhesive layer, and a copper foil layer. Composed of layers. On the other hand, the two-layer flexible substrate is a laminated board composed of two layers, a base film layer and a copper foil layer, using a special construction method without using an adhesive. Since the two-layer flexible substrate does not include an adhesive layer with low heat resistance such as an epoxy resin or an acrylic resin, the two-layer flexible substrate has high reliability, and the entire circuit can be thinned, and the amount of use is increasing. On the other hand, from a different viewpoint, the base film layer of the flexible substrate is desired to have a low thermal expansion coefficient in order to prevent curling, but a polyimide resin having a low thermal expansion coefficient is inferior in adhesiveness. When using all the polyimide resin without using an adhesive, it was necessary to provide a good adhesion polyimide resin layer as an adhesion-imparting layer on the adhesive surface side. A flexible substrate having a copper foil layer on both sides is also known. After manufacturing a single-sided flexible substrate having a copper foil layer on one side, a method of stacking two flexible substrates on top of each other or copper on a single-sided flexible substrate A method of laminating and stacking foils is known.

  In recent years, there is an increasing demand for higher performance and higher functionality in electronic devices, and accordingly, higher density of printed wiring boards, which are circuit board materials used in electronic devices, is desired. In order to increase the density of the printed wiring board, it is necessary to reduce the width and interval of the circuit wiring, that is, to make the pitch finer. In addition, dimensional stability during circuit processing is also required. Further, the etching accuracy at the time of etching of the polyimide resin layer is not an exception, and the requirements for the processing shape after etching are severe. In general, the thermoplastic polyimide used as the adhesive layer is different from the low thermal expansion polyimide used as the base of the polyimide resin layer in terms of dissolution rate (etching rate) with an alkali treatment solution, etc., and therefore undercutting during etching processing. There arises a problem that it occurs or the adhesive layer remains in a hook shape.

  Therefore, in order to improve the etching shape of the polyimide resin layer during etching, a material in which the thickness of the thermoplastic polyimide layer, which is an adhesive layer, is reduced is 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, in this method, since it is necessary to pay sufficient attention to the etching rate of non-thermoplastic polyimide and thermoplastic polyimide, it is difficult to accurately control the etching shape including overetching and undercutting. Moreover, in order to improve the etching shape at the time of the etching process of a polyimide resin layer, the material which made the polyimide resin layer the single layer is proposed (patent document 3). However, such a polyimide resin layer has a thermoplastic polyimide as a base layer, and its thermal expansion coefficient is larger than that of metal, so that it has been difficult to control the dimensional stability of the material.

JP-A-2006-190824 Japanese Patent Laid-Open No. 2005-111858 Japanese Patent Laid-Open No. 2004-276413

  In addition, as a method for forming a polyimide resin layer having an adhesive layer, a precursor solution of a non-thermoplastic polyimide resin is applied on a substrate and dried, and a precursor solution of a thermoplastic polyimide resin is applied thereon and dried. However, a method of curing is conventionally known, and for example, disclosed in Patent Document 1. In this case, the thermoplastic polyimide resin layer becomes the adhesive layer, but a thickness of a certain level or more is necessary to give the desired adhesiveness, and as a result, the problem of the etching shape or the like occurs as described above.

  The present invention has an adhesive layer that gives a high adhesion to the metal layer by forming a specific adhesive layer on the polyimide resin layer and does not generate an undercut or wrinkle-like etching residue during polyimide etching. An object of the present invention is to provide a method for producing a polyimide resin layer and to provide a metal-clad laminate that can cope with an extremely thin insulating resin layer while ensuring sufficient adhesive strength to meet the fine pitch of printed circuit boards. And Another object is to provide a method for producing a double-sided metal-clad laminate.

  In order to achieve the above-mentioned object, the present inventors have studied, and by appropriately improving the formation of the adhesive layer of the polyimide resin layer, the polyimide resin layer using this has an adhesive strength with the metal layer. And the inventors have found that it is easy to control the shape during polyimide etching and have completed the present invention.

That is, the present invention is a method for producing a polyimide resin layer having an adhesive layer,
a) On the polyamic acid layer which is a precursor of a low thermal expansion polyimide resin having a thermal linear expansion coefficient of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), the solid content concentration is 0.1 weight. An impregnation layer forming step of applying a precursor solution of thermoplastic polyimide resin in a thickness of 1.0 to 3% by weight to impregnate a part or all of the solution into a polyamic acid layer;
b) It is provided with an adhesive layer forming step in which the polyamic acid layer on which the impregnated layer is formed is dried and imidized by heat treatment to form an adhesive layer having a thickness of less than 1.0 μm on the polyimide resin layer. This is a method for producing a polyimide resin layer having an adhesive layer.

（式（１）中、Ar₁は式（２）、式（３）又は式（４）で表される２価の芳香族基を示し、Ar₂は式（５）又は式（６）で表される４価の芳香族基を示す。式（２）〜式（４）及び式（６）において、R₁は独立に炭素数１〜６の１価の炭化水素基又はアルコキシ基を示し、nは独立に０〜４の整数を示し、X及びWは独立に単結合又は-C(CH₃)₂-、-(CH₂)m-、-O-、-S-、-CO-、-SO₂-、-NH-若しくは-CONH-から選ばれる２価の基を示し、mは１〜５の整数を示す。そして、Ar₁1モル中に-(CH₂)m-、-O-、-S-、-CO-、-SO₂-、-NH-及び-CONH-から選ばれる２価の基(Y)を合計で1〜3モル含む。） Moreover, this invention is a manufacturing method of said polyimide resin layer whose precursor of a thermoplastic polyimide resin has a structural unit represented by following formula (1).

(In formula (1), Ar ₁ represents a divalent aromatic group represented by formula (2), formula (3) or formula (4), and Ar ₂ represents formula (5) or formula (6). In the formulas (2) to (4) and (6), R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms. , N independently represents an integer of 0 to 4, and X and W independently represent a single bond or —C (CH ₃ ) ₂ —, — (CH ₂ ) m—, —O—, —S—, —CO—. , —SO ₂ —, —NH— or —CONH—, wherein m represents an integer of 1 to 5. And in 1 mol of Ar ₁ , — (CH ₂ ) m—, — 1 to 3 mol in total of divalent groups (Y) selected from O—, —S—, —CO—, —SO ₂ —, —NH— and —CONH— are included.)

In the above formula (1), Ar ₂ 1 in molar include 0.4-0.8 moles above divalent group of (Y) in total, or Ar ₁ and the divalent on total 2 moles of Ar ₂ The total amount of the group (Y) is 1.6 to 2.4 mol, or Ar ₂ is represented by the formula (6) and W is —SO ₂ —, and has a tetravalent aromatic group. If one or more is satisfied, an excellent adhesive layer is provided.

Furthermore, the present invention provides a method for producing a metal-clad laminate,
I) an adhesive layer forming step of forming an adhesive layer on one side of the polyimide resin layer;
II) A method for producing a metal-clad laminate, comprising a step of forming a metal layer on the surface of the adhesive layer, wherein step I) comprises the steps a and b.

  Here, it is suitable that the step II) includes c) a step of superimposing a metal foil on the surface of the adhesive layer and thermocompression bonding, or d) a step of depositing a metal thin film layer on the surface of the adhesive layer.

  Hereinafter, the present invention relating to a method for producing a polyimide resin layer having an adhesive layer will be described, and then the present invention relating to a method for producing a metal-clad laminate will be explained, but common parts will be explained simultaneously.

  The polyimide resin layer having an adhesive layer obtained by the production method of the present invention has a polyimide resin layer (1) and an adhesive layer (2) on one or both sides thereof, but the adhesive layer (2) also has It consists of a polyimide resin layer (2). The adhesive layer (2), that is, the polyimide resin layer (2) has higher adhesiveness than the polyimide resin layer (1). The polyimide resin layer having an adhesive layer is preferably a polyimide resin film or film.

  Hereinafter, the polyimide resin layer (1) is sometimes referred to as a polyimide resin layer, and the adhesive layer (2) or the polyimide resin layer (2) is sometimes referred to as an adhesive layer. When it is necessary to distinguish the polyimide resin layer (1) from the adhesive layer (2) or the polyimide resin layer (2), the former is referred to as the polyimide resin layer (1) and the latter is referred to as the adhesive layer. Moreover, the polyamic acid which is the precursor of the polyimide resin which forms a polyimide resin layer (1) may be abbreviated as a polyamic acid. The precursor of the thermoplastic polyimide resin that forms the adhesive layer (2) or the polyimide resin layer (2) may be abbreviated as a precursor. Since the polyamic acid or precursor and the polyimide resin are in a relationship between the precursor and the product, the structure of the other is understood by explaining one of them.

  The aspect of the polyimide resin layer having an adhesive layer is not particularly limited, and may be a film (sheet) or may be in a state of being laminated on a substrate such as a metal foil, a glass plate, or a resin film. In addition, the base material here means a sheet-like resin or metal foil on which a polyimide resin layer is laminated. However, the adhesive layer laminated | stacked on the single side | surface or both surfaces of a polyimide resin layer exists as a surface layer. The total thickness of the polyimide resin layer having an adhesive layer is in the range of 3 to 100 μm, preferably 3 to 50 μm.

  The polyimide resin can be formed by curing (imidizing) a polyamic acid that is a precursor of the polyimide resin. Details of the curing will be described later.

  Examples of the polyimide resin that can be applied as the polyimide resin layer include heat-resistant resins having an imide group in a structure such as polyamideimide, polybenzimidazole, polyimide ester, polyetherimide, polysiloxaneimide, and the like including so-called polyimide resins.

In the method for producing a polyimide resin layer having an adhesive layer of the present invention, the polyimide resin layer (1) is preferably a polyimide resin layer having low adhesion and low thermal expansion. Specifically, the thermal expansion coefficient is 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), preferably 1 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K), more preferably 15 ×. When applied to a low thermal expansion polyimide resin layer of 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K), a great effect is obtained. Therefore, as the polyamic acid layer, a layer that gives the polyimide resin layer by imidizing it is used.

但し、Ar₃は式（８）又は式（９）で表される４価の芳香族基を示し、Ar₄は式（１０）又は式（１１）で表される２価の芳香族基を示し、R₂は独立に炭素数１〜６の1価の炭化水素基又はアルコキシ基を示し、V及びYは独立に単結合又は炭素数１〜１５の２価の炭化水素基、O、S、CO、SO、SO₂若しくはCONHから選ばれる２価の基を示し、ｍは独立に０〜４の整数を示し、qは構成単位の存在モル比を示し、０．１〜１．０の範囲である。 As a polyimide resin which comprises the said polyimide resin layer, the polyimide resin which has a structural unit represented by General formula (7) is preferable.

However, Ar ₃ represents a tetravalent aromatic group represented by formula (8) or formula (9), and Ar ₄ represents a divalent aromatic group represented by formula (10) or formula (11). R ₂ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, V and Y independently represent a single bond or a divalent hydrocarbon group having 1 to 15 carbon atoms, O, S , CO, SO, SO ₂ or CONH represents a divalent group, m independently represents an integer of 0 to 4, q represents a molar ratio of constituent units, and represents 0.1 to 1.0. It is a range.

  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 resins having such a structural unit, a polyimide resin that can be suitably used is a non-thermoplastic polyimide resin. A non-thermoplastic polyimide resin is excellent in low thermal expansion, but has a feature of poor adhesion.

Since a polyimide resin is generally produced by reacting an acid anhydride and a diamine, a specific example of the polyimide resin can be understood by explaining the acid anhydride and the diamine. In the general formula (7), Ar ₃ can be referred to as an acid anhydride residue, and Ar ₄ can be referred to as a diamine residue. Therefore, a preferred polyimide resin will be described using an acid anhydride and a diamine. However, it is not limited to the polyimide resin obtained by this method.

Examples of the acid anhydride include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, Preferred is 4,4′-oxydiphthalic anhydride.
Also, 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 dianhydride, bis (2, Preferable examples include 3-dicarboxyphenyl) ether dianhydride. 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- Alternatively, 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane dianhydride and the like are preferable.

  Other acid anhydrides include 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-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7- Naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic 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 acid Dianhydride, 2,3,6,7- (or 1,4,5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic acid di Anhydride, 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-tetracar Boronic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5- Examples thereof include tetracarboxylic dianhydride and 4,4′-bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride.

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'- Preferred examples include diaminobiphenyl and 4,4′-diaminobenzanilide.
Also, 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-amino Phenoxy) phenyl] ether, bis [4- (4-aminophenoxy)] benzophenone, bis [4- (3-aminophenoxy)] benzophenone, bis [4,4 ′-(4-aminophenoxy)] benzanilide, bis [ Four, 4 ′-(3-aminophenoxy)] benzanilide, 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3-aminophenoxy) phenyl] fluorene and the like are preferable. Can be mentioned.

  Other diamines include 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'-diamino Diphenylpropane, 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'-di Minobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4 ''-diamino-p-terphenyl, 3,3 ''-diamino-p-ter Phenyl, m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 1,4-bis (4-aminophenoxy) benzene, 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, Examples include 5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine and the like.

  Each of acid anhydrides and diamines may be used alone or in combination of two or more. Further, other acid anhydrides or diamines not included in the general formula (7) can be used together with the above acid anhydrides or diamines. In this case, the other acid anhydrides or diamines are used in a proportion of 90 mol. % Or less, preferably 50 mol% or less. Control the thermal expansion, adhesiveness, glass transition point (Tg), etc. by selecting the type of acid anhydride or diamine and the molar ratio of each of two or more acid anhydrides or diamines. be able to.

  The synthesis of the polyamic acid which is a precursor of the polyimide resin can be performed by reacting approximately equimolar acid anhydride and diamine 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 method for forming the polyamic acid layer is not particularly limited, for example, it can be formed by applying a polyimide acid solution on the substrate and then drying, but the method for applying is not particularly limited, and a comma, die, knife, It can be applied with a coater such as a lip. Thereafter, it is dried to form a polyamic acid layer.

It does not restrict | limit especially as a method to dry, For example, it is good to carry out for 1 to 60 minutes on 60-200 degreeC temperature conditions. In this drying step, the temperature is controlled on the side where the adhesive layer is formed so that imidization due to the progress of dehydration and ring closure of the polyamic acid is not completed. For this purpose, it is preferable to perform drying under a temperature condition of 60 to 150 ° C. It is necessary to leave the polyamic acid state on the side on which the adhesive layer is formed in order to impregnate the precursor solution of the thermoplastic polyimide resin. The polyamic acid layer after drying may have a part of the polyamic acid structure imidated as described above, but the imidization rate is 50% or less, more preferably 20% or less, and the polyamic acid structure remains at 50% or more. It is good. The imidization ratio of the polyamic acid is 1,000 cm by measuring the infrared absorption spectrum of the polyimide thin film by a transmission method using a Fourier transform infrared spectrophotometer (commercial product: FT / IR620 manufactured by JASCO Corporation). ^-1 benzene ring carbon hydrogen bond as a reference is calculated from the absorbance from the imide groups of 1,720 cm ^-1.

  The polyamic acid layer may be formed of only a single layer or may be composed of a plurality of layers. When the polyamic acid layer is composed of a plurality of layers, it can be formed by sequentially applying other polyamic acids on the polyamic acid layer composed of different components. When the polyamic acid layer is composed of three or more layers, the polyamic acid having the same configuration may be used twice or more. Two layers or a single layer, in particular a single layer, having a simple layer structure can be advantageously obtained industrially. In the case of a plurality of layers, the polyamic acid layer in contact with the adhesive layer is a polyamic acid layer that is a precursor of the low thermal expansion polyimide resin layer. The thickness of the polyamic acid layer (after drying) is 3 to 100 μm, preferably 3 to 50 μm.

  In the method for producing a polyimide resin layer having an adhesive layer according to the present invention, a) a thermoplastic polyimide having a solid content concentration of 0.1 wt% to 3 wt% on a polyamic acid layer which is a precursor of the polyimide resin. A resin precursor solution is applied in a thickness of 1.0 μm or more, and an impregnation layer forming step (step a) is performed in which part or all of the solution is impregnated into the polyamic acid layer.

  The precursor of a thermoplastic polyimide resin (hereinafter also referred to as a precursor) can be a known thermoplastic polyimide resin precursor obtained from a known acid anhydride and diamine, 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 obtained polyimide precursor resin is 5 to 30 wt%, preferably 10 to 20 wt% 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 weight average molecular weight of the precursor of the thermoplastic polyimide resin is preferably in the range of 10,000 to 500,000, more preferably 100,000 to 400,000, and still more preferably 200,000 to 300,000. It is better to be in the range. The weight average molecular weight can be controlled by the use ratio of tetracarboxylic dianhydride and diamine, and the reaction temperature and reaction time of the polymerization reaction when the precursor of the thermoplastic polyimide resin is produced.

  The solid content concentration of the precursor solution of the thermoplastic polyimide resin is 0.1 wt% to 3 wt%, preferably 0.5 wt% to 2.5 wt%, more preferably 1 wt% to 2 wt%. The solid content here is understood to be the precursor of the thermoplastic polyimide resin itself. Further, in calculating the solid content concentration, the weight of the solid content is divided by the weight of the polyimide precursor resin solution and expressed as a percentage (%). When the solid content concentration is higher than 3% by weight, it becomes difficult to ensure sufficient adhesive strength with the metal layer when the thickness of the adhesive layer is 1 μm or less.

  The polyimide precursor resin solution may contain an unreacted anhydride and a diamine or oligomer, and the carboxyl group or amino group that these have are bound to the terminal carboxyl group or terminal amino group present in the polyamic acid layer. The ring reaction is considered to further improve the adhesion.

  The solid content concentration of the precursor of the thermoplastic polyimide resin is within the above range, so that the impregnation effect can be effectively utilized regardless of the weight average molecular weight of the precursor of the thermoplastic polyimide resin. For example, a low molecular weight type polyimide precursor resin having a weight average molecular weight of less than 10,000 can suppress in-plane variation of the adhesive layer accompanying the thinning of the adhesive layer, while the weight average molecular weight is 200, Even in a high molecular weight type polyimide precursor resin of 000 or more, the polyamic acid layer can be easily impregnated, and the amount of the polyimide precursor resin deposited on the surface of the polyamic acid layer can be suppressed. When the amount is less than the above lower limit, even if the amount of the precursor solution impregnated in the polyamic acid layer is constant, the amount of the precursor of the thermoplastic polyimide resin is insufficient, so that the adhesive strength tends to decrease. . Further, when the above upper limit is exceeded, the impregnation effect of the polyimide precursor resin solution is difficult to obtain, and the amount of the polyimide precursor resin deposited on the surface of the polyamic acid layer increases. The thickness tends to change.

  In addition, by setting the solid content concentration within the above range, swelling of the extreme surface layer of the polyamic acid layer due to contact with the solvent of the polyimide precursor resin solution is likely to occur, and the polyimide precursor resin is effectively applied to the swollen portion. It is considered to be impregnated. This effect is considered to appear immediately after the start of application of the polyimide precursor resin solution, that is, when the polyamic acid layer comes into contact with the polyimide precursor resin solution, and thus can be dealt with by a conventionally known application method, for example, application time A certain effect can be obtained without increasing the length of the film, or increasing the time for which the coating is left after the application is completed, or without special control in the application process.

  A polyimide precursor resin solution is applied to the surface of the polyamic acid layer, and part or all of the polyamic acid layer is impregnated in the polyamic acid layer. Advantageously, 50% or more, preferably 80% or more is impregnated. Therefore, after coating and impregnation, each layer has a polyamic acid layer, an impregnated layer, and an unimpregnated precursor resin solution layer (if there is unimpregnated), and after drying and imidization, an imidized resin layer is formed. Will have. Here, since the polyamic acid layer is a polyimide resin layer that gives the basic performance (low thermal expansion, etc.) of the polyimide resin layer having the adhesive layer of the present invention, it has a thickness of 50% or more of the whole. Good. Since the resin layer formed by imidizing the impregnated layer and the unimpregnated precursor resin solution layer provides an adhesive layer, the thickness should be less than 1 μm, preferably 0.2 to 0.8 μm. . The amount of impregnation can be controlled by adjusting the solid content concentration within the above range. And the properties such as etching property of the polyimide resin layer generated from the impregnated layer are almost equal to the main component polyimide resin layer (1), but the polyimide resin layer generated from the unimpregnated precursor resin solution layer is the polyimide resin layer (1) Is a heterogeneous polyimide resin layer, and its thickness should be less than 0.5 μm, preferably less than 0.2 μm. From another viewpoint, the ratio of the thickness of the impregnated layer and the unimpregnated precursor resin solution layer in the adhesive layer may be 10: 0-5, preferably 10: 0-2, The thickness of the adhesive layer with respect to the total thickness 100 of the polyimide resin layer having a thickness of 0.5 to 20, preferably 1 to 10. In order to control to such a thickness, it is possible to control the concentration of the precursor resin solution and the coating thickness and impregnation time of the precursor resin solution, particularly the concentration and the coating thickness. The thickness ratio of the impregnated layer in the adhesive layer is preferably 80% or more.

  After coating and impregnation, the polyamic acid and the precursor are cured by drying and heat treatment to form a polyimide resin, and a polyimide resin layer and an adhesive layer having a thickness of 1 μm are formed (step b). Here, the adhesive layer formed by the heat treatment is a layer derived from the precursor resin solution, and the thickness of the adhesive layer from the impregnated layer and the unimpregnated precursor resin layer is measured by a transmission electron microscope (TEM). ) Can be measured.

  The polyimide precursor resin solution is preferably used after the reaction solvent solution is diluted with an organic polar solvent to obtain a concentration within the above range. The organic polar solvent is preferably one used for the polymerization reaction, more preferably N, N-dimethylacetamide or N-methyl-2-pyrrolidone, and by selecting such a solvent as a dilution solvent, The impregnation effect on the polyamic acid layer is easily obtained.

  The polyimide precursor resin solution has a coating thickness (hereinafter referred to as wet thickness) of 1.0 μm or more, and the thickness of the adhesive layer formed in the subsequent adhesive layer forming step is less than 1.0 μm, preferably 0.00. The thickness may be in the range of 05 to 0.8 μm, more preferably 0.1 to 0.5 μm. The wet thickness of the polyimide precursor resin solution is preferably 10 to 70 μm, more preferably 20 to 50 μm, and the thickness of the adhesive layer formed in the adhesive layer forming step is controlled by such a range. It can be within the above range. The method of applying the polyimide precursor resin solution is not particularly limited, and can be applied with a coater such as a comma, die, knife, lip, etc. The application may be performed in several steps. It is industrially advantageous to make the wet thickness by applying the resin once. When the desired wet thickness is 30 μm or more and the desired wet thickness is obtained by applying only once, for example, a die coater having a discharge port height equivalent to the wet thickness can be used, It is preferable to use a lip coater in which the gap distance is a wet thickness. Further, the impregnation method does not require any special operation, and the impregnation can be performed in the process of the above-described application and the operation by drying described later. For example, it is possible to increase the impregnation time by setting the drying temperature lower.

  Also, the drying and curing methods are not particularly limited, and for example, heat treatment such as heating for 1 to 60 minutes at a temperature of 80 to 400 ° C. is suitably employed. In order to obtain the impregnation effect, the drying preferably has a step of holding at 120 to 130 ° C. for 1 to 3 minutes. The polyimide resin layer in which the polyimide resin layer is formed on the substrate may be used as it is, or may be used after being peeled off.

The precursor of the thermoplastic polyimide resin preferably has a structural unit represented by the formula (1). In Formula (1), Ar ₁ represents a divalent aromatic group represented by Formula (2), Formula (3), or Formula (4), and Ar ₂ is represented by Formula (5) or Formula (6). Represents a tetravalent aromatic group. In the formulas (2) to (4), R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, n independently represents an integer of 0 to 4, and X and W are 2 independently selected from a single bond or —C (CH ₃ ) ₂ —, — (CH ₂ ) m—, —O—, —S—, —CO—, —SO ₂ —, —NH— or —CONH—. Represents a valent group, and m represents an integer of 1 to 5. Here, a divalent group selected from — (CH ₂ ) m—, —O—, —S—, —CO—, —SO ₂ —, —NH— or —CONH— (hereinafter referred to as a divalent group ( Y)) is a flexible group that gives flexibility to the polyimide resin, and a single bond and -C (CH ₃ ) ₂ -is a group that gives rigidity, so the thermoplastic polyimide can be controlled by controlling the balance The properties of the resin can be adjusted.

In the above general formula (1), Ar ₁ can be referred to as a diamine residue, and Ar ₂ 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 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'-diamino Biphenyl, 4,4′-diaminobenzanilide and the like can be mentioned. In addition, the diamine mentioned by description of the said polyimide resin can be mentioned. Among these, particularly preferable diamine components include 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane (DANPG), 2,2-bis [4- (4-aminophenoxy) phenyl] propane ( BAPP), 1,3-bis (3-aminophenoxy) benzene (APB), paraphenylenediamine (p-PDA), 3,4'-diaminodiphenyl ether (DAPE34), 4,4'-diaminodiphenyl ether (DAPE44) One or more selected diamines are preferred.

  Examples of the acid anhydride include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride. In addition, the acid anhydride mentioned by description of the said polyimide resin can be mentioned. Among these, particularly preferred acid anhydrides include pyromellitic anhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3', 4,4'- Examples thereof include at least one acid anhydride selected from benzophenone tetracarboxylic dianhydride (BTDA) and 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA).

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

  The precursor of the thermoplastic polyimide resin may be a structural unit represented by the formula (1) in the homopolymer or may be present as a structural unit of the copolymer. When they are combined, they may exist as blocks or randomly. The structural unit represented by the formula (1) is plural, but may be one type or two or more types. Advantageously, the main component is the structural unit represented by the formula (1), and it is preferably a polyimide precursor resin containing 60 mol% or more, more preferably 80 mol% or more.

The divalent group (Y) which is a flexible group contributes to the adhesiveness of the obtained polyimide resin. The adhesiveness of the polyimide resin is preferably such that the ratio of the divalent group (Y) contained in the polyimide precursor resin is 1.0 mol or more with respect to 1 mol of Ar _2. As the proportion of Y) increases, the mechanical strength (for example, tear strength) of the polyimide resin itself tends to decrease. Therefore, the proportion of the divalent group (Y) is set to 3.0 with respect to 1 mol of Ar _2. It is preferable to make it less than mol.

Further, the precursor of the thermoplastic polyimide resin, in the formula (1), the divalent group in Ar ₂ relative to Ar ₁ 1 mole (Y) is good to be included from 0.4 to 0.8 mol. Preferably, the divalent group (Y) is contained in an amount of 1.6 to 2.4 mol with respect to 2 mol in total of Ar ₁ and Ar ₂ . Since the thermoplastic polyimide resin obtained from the precursor of the thermoplastic polyimide resin can advantageously utilize the impregnation effect according to the present invention, the function as an adhesive layer can be improved. Incidentally, Ar ₁ and Ar ₂ as is apparent from equation (1) because there equimolar, Ar ₁ 1 mole is calculated to Ar ₂ 1 mol.

Further, the precursor of the thermoplastic polyimide resin in the formula (1) preferably includes the one in which W is —SO ₂ — in the formula (6). Such a thermoplastic polyimide resin precursor is considered to have a high impregnation effect because it has a high polarity —SO ₂ — to improve compatibility with an organic polar solvent.

  In the precursor of the thermoplastic polyimide resin used in the present invention, a specific example of a preferable combination of a diamine component and an acid anhydride component will be described. When the diamine component is 100 mol%, APB is an essential component as the diamine, preferably 50 to 100 mol%, more preferably 60 to 90 mol%. Moreover, when using together diamine other than APB, it is preferable to use 10-30 mol% of p-PDA, More preferably, 10-30 mol%. Furthermore, when the acid anhydride component is 100 mol%, DSDA is an essential component as the acid anhydride, preferably 50 to 100 mol%, more preferably 60 to 90 mol%. When an acid anhydride other than DSDA is used in combination, at least one of PMDA and BPDA is used in an amount of 10 to 40 mol%, more preferably 20 to 40 mol%.

  Next, the details of the method for producing the metal-clad laminate of the present invention will be described. Step I) The adhesive layer forming step of forming an adhesive layer on one side of the polyimide resin layer can be performed in the same manner as the method for producing a polyimide resin layer having an adhesive layer. The polyimide resin layer obtained by this method (hereinafter also referred to as an adhesive polyimide resin layer) is subjected to Step II). That is, after being subjected to step a and step b in the method for producing a metal-clad laminate, it is subjected to step II). In step II), a metal layer is formed on the surface of the adhesive layer. As this forming method, a method of forming a metal layer by a thermocompression bonding method and a vapor deposition method is suitable. The thermocompression bonding method has a step c in addition to the steps a and b. A method for forming a metal thin film by vapor deposition or the like includes a step d in addition to the steps a and b.

  In step c, the method for thermocompression bonding the metal foil 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.

  In thermocompression bonding, it is preferable to press the metal foil while heating in the range of 150 to 450 ° C. 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, copper foil (copper alloy foil) or stainless steel foil is suitable. The copper foil here means copper or a copper alloy foil containing copper as a main component. Preferably, the copper foil has a copper content of 90% by mass or more, particularly preferably 95% by mass or more. Examples of the metal contained in the copper foil include chromium, zirconium, nickel, silicon, zinc, and beryllium. An alloy foil containing two or more of these metals may also be used. The stainless steel foil is not limited in material, but for example, a stainless steel foil such as SUS304 is preferable.

  The metal foil may be treated with a silane coupling agent on the surface on which the polyimide resin layer is laminated. 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 / or 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.

  An example in which the metal foil is a copper foil includes a case where the metal foil is used for a flexible substrate. The preferred thickness of the copper foil when used as this application is in the range of 3 to 50 μm, more preferably in the range of 5 to 30 μm, but the copper-clad laminate used in applications where fine pitch is required, A thin copper foil is preferably used, and in this case, a range of 5 to 20 μm is suitable. Moreover, since the adhesiveness with respect to a resin layer is acquired even if it uses copper foil with small surface roughness, this invention is suitable especially when using copper foil with small surface roughness. The preferred surface roughness of the copper foil is 10-point average roughness in the range of 0.1 to 3 μm. Particularly for copper foils used in applications requiring a fine pitch, a surface roughness of 10-point average roughness of 0.1 to 1.0 μm is suitable.

  An example in which the metal foil is a stainless steel foil is a case where the metal foil is used for a suspension (hereinafter referred to as HDD suspension) mounted on a hard disk drive. The preferred thickness of the stainless steel foil when used for this purpose is in the range of 10 to 100 μm, more preferably in the range of 15 to 70 μm, and still more preferably in the range of 15 to 50 μm.

  The laminate obtained by this method for producing a metal-clad laminate is a laminate having a metal foil on one or both sides of a polyimide resin layer. A laminate having a metal foil on one side is obtained by laminating a metal foil on an adhesive layer obtained by the method for producing a polyimide resin layer having an adhesive layer of the present invention. When the polyimide resin layer having an adhesive layer is laminated on a substrate such as glass or a resin film, it is peeled off from the substrate as necessary. When the polyimide resin layer which has an adhesive layer is laminated | stacked on metal foils, such as copper foil, it can be set as a double-sided metal-clad laminate by laminating | stacking metal foil on this polyimide resin layer side. In addition to the above method, the metal-clad laminate having metal foil on both sides should be laminated on both sides if the polyimide resin layer having an adhesive layer has an adhesive layer on both sides. Is obtained.

  Next, the manufacturing method of the metal-clad laminated board of this invention provided with the process d in addition to the process a and the process b is demonstrated. Steps a and b are performed as described above, and are then applied to step d, that is, a metal thin film layer is formed on the surface of the adhesive layer in step d.

In step d, 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.

  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.

  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 d 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.

  According to the present invention, an excellent metal-clad laminate is provided because the polyimide resin layer is imparted with high adhesion to the metal layer by a simple process and does not cause undercuts or saddle-like etching residue during polyimide etching. It becomes possible to do. 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.

  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, unless otherwise specified, various measurements and evaluations are as follows.

[Measurement of adhesive strength]
The adhesive strength was evaluated by measuring 90 °, 1 mm peel strength at room temperature for a sample cut into 1 mm width strips using a strograph VES05D (Toyo Seiki Seisakusho).

[Measurement of thermal linear expansion coefficient]
The coefficient of linear thermal expansion was determined by using a thermomechanical analyzer (manufactured by Seiko Instruments Inc.), raising the temperature of the sample to 250 ° C., holding the sample at that temperature for 10 minutes, and then cooling at a rate of 5 ° C./min. To an average linear thermal expansion coefficient (CTE) from 100 ° C to 100 ° C.

[Measurement of adhesive layer thickness]
The thickness of the adhesive layer was evaluated 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 checking the thickness of the modified layer.

[Measurement of polyimide etching shape]
First, a 100 mm square metal-clad laminate was used, the metal layer side was etched, and a 100 μm diameter via was formed as a test piece. Thereafter, using the metal layer as an etching mask, an aqueous solution of 33.5 wt% potassium hydroxide, 11 wt% ethylenediamine, and 22 wt% ethylene glycol was used as an etching solution, and the test piece was immersed in an etching solution at 80 ° C. 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.

  Next, the present invention will be specifically described based on the following examples. Of course, the present invention is not limited to this. The abbreviations used in this example are as described above.

Production Example 1
In a 500 ml separable flask, 20.7 g of 2′-methoxy-4,4′-diaminobenzanilide (0.08 mol) was dissolved in 343 g of DMAc with stirring. Next, 28.5 g PMDA (0.13 mol) and 10.3 g DAPE44 (0.05 mol) were added to the solution in a nitrogen stream. Thereafter, stirring was continued for about 3 hours to conduct a polymerization reaction, and a viscous polyamic acid solution S was obtained.
The obtained polyamic acid solution S was applied on a stainless steel substrate, dried at 130 ° C. for 5 minutes, heated to 360 ° C. over 15 minutes to complete imidization, and laminated on the stainless steel substrate. A polyimide film was obtained. This polyimide film was peeled from the stainless steel substrate to obtain a polyimide film S having a thickness of 25 μm. The linear thermal expansion coefficient of this film S was 14.6 × 10 ⁻⁶ (1 / K).

Production Example 2
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. Stainless steel foil 1 (Shin Nippon Steel Co., Ltd. SUS304 H-TA, thickness 20 μm, surface roughness on the resin layer side: 10-point average roughness Rz 0.8 μm) washed in advance with a silane coupling agent solution (liquid temperature about 20) C.) for 30 seconds and then pulled up into the atmosphere to remove excess liquid. Then, it was dried by blowing compressed air for about 15 seconds. Thereafter, heat treatment was performed at 110 ° C. for 30 minutes to obtain a stainless steel foil 2 treated with a silane coupling agent.

Synthesis example 1
In a 500 ml separable flask, 11.7 g APB (0.04 mol) and 2.2 g p-PDA (0.02 mol) were dissolved in 262 g DMAc with stirring. The solution was then charged with 4.4 g PMDA (0.02 mol) and 14.3 g DSDA (0.04 mol) in a stream of nitrogen. Thereafter, stirring was continued for about 4 hours to carry out a polymerization reaction, and a viscous polyimide precursor resin a solution was obtained. The weight average molecular weight of the obtained polyimide precursor resin a was 286,000. In addition, the value of the standard polystyrene conversion weight average molecular weight measured using gel permeation chromatography (GPC) was calculated | required.
Here, the polyimide precursor resin a, in the above-mentioned formula (1), the divalent Ar ₁ relative to Ar ₂ 1 mole group (Y) is the Ar ₂ relative to 1.33 mole, Ar ₁ 1 mole divalent group (Y) is 0.66 moles, divalent groups of Ar ₁ and Ar ₂ relative to Ar ₁ 1 mole (Y) contains 1.99 mol.

Synthesis example 2
In a 500 ml separable flask, 14.6 g APB (0.05 mol) and 5.4 g p-PDA (0.05 mol) were dissolved in 359 g DMAc with stirring. The solution was then charged with 8.7 g PMDA (0.04 mol) and 21.5 g DSDA (0.06 mol) in a stream of nitrogen. Thereafter, stirring was continued for about 4 hours to carry out a polymerization reaction, thereby obtaining a viscous polyimide precursor resin b solution.

Synthesis example 3
In a 1000 ml separable flask, 26.3 g APB (0.09 mol) and 1.1 g p-PDA (0.01 mol) were dissolved in 411 g DMAc with stirring. The solution was then charged with 8.7 g PMDA (0.04 mol) and 21.5 g DSDA (0.06 mol) in a stream of nitrogen. Thereafter, stirring was continued for about 4 hours to conduct a polymerization reaction, and a viscous polyimide precursor resin c solution was obtained.

Synthesis example 4
In a 1000 ml separable flask, 29.2 g APB (0.1 mol) was dissolved in 409 g DMAc with stirring. The solution was then charged with 8.7 g PMDA (0.04 mol) and 19.3 g BTDA (0.06 mol) in a stream of nitrogen. Thereafter, stirring was continued for about 3 hours to conduct a polymerization reaction, and a viscous polyimide precursor resin d solution was obtained.

Synthesis example 5
In a 1000 ml separable flask, 41.1 g BAPP (0.1 mol) was dissolved in 524 g DMAc with stirring. Next, 32.2 g of BTDA (0.1 mol) was added to the solution in a nitrogen stream. Thereafter, stirring was continued for about 2 hours to carry out a polymerization reaction, and a viscous polyimide precursor resin e solution was obtained.

Synthesis Example 6
In a 500 ml separable flask, 28.7 g BAPP (0.07 mol) was dissolved in 320 g DMAc with stirring. The solution was then charged with 13.1 g PMDA (0.06 mol) and 2.9 g BPDA (0.01 mol) in a stream of nitrogen. Thereafter, the polymerization reaction was continued for about 3 hours to obtain a viscous polyimide precursor resin f solution.

The synthesis examples 1 to 6 are summarized in Table 1. In Table 1, the unit of the amount of diamine and acid anhydride used is g (the numerical value in parentheses represents the number of moles), and “precursor” indicates the obtained polyimide precursor resin, “Ar ₁ “Y” indicates the number of moles of the divalent group (Y) in 1 mole of Ar ₁ , and “Y of Ar ₂ ” means the number of moles of the divalent group (Y) in 1 mole of Ar ₂ “Y of Ar ₁ Ar ₂ ” indicates the number of moles of the divalent group (Y) in a total of 2 moles of Ar ₁ and Ar ₂ .

A polyimide precursor resin solution A prepared by adding 453 g of DMAc to 47 g of the polyimide precursor resin a solution of Synthesis Example 1 and adjusting the solid content concentration to 1% by weight was prepared.
The polyamic acid solution S of Production Example 1 was applied onto a stainless steel substrate so that the thickness after imidization was 25 μm, and dried at 130 ° C. for 5 minutes to produce a polyamic acid layer.
On the polyamic acid layer, a polyimide coater resin solution A was applied with a wet thickness of 50 μm using a die coater (discharge port height: 50 μm), then dried at 130 ° C. for 2 minutes, and 360 ° C. over 15 minutes. The polyimide resin layer which has an adhesive layer was produced by heating up to complete the imidization. The polyimide film 1 which has an adhesive layer was obtained by peeling the obtained resin layer from a base material. The thickness of the adhesive layer of this film was 0.4 μm. Further, almost 100% of the adhesive layer was an impregnated layer.

  Note that the ratio W (%) of the impregnated layer in the adhesive layer is the theoretical thickness F0 (μm) after imidation of the polyamic acid layer, the thickness F1 (μm) of the polyimide film 1 and the thickness T ( μm) was calculated as W (%) = [T− (F1−F0)] / T × 100 (%). Here, “theoretical thickness after imidization of the polyamic acid layer” means that after the polyamic acid layer is formed, the polyamic acid layer is simply imidized without applying the precursor solution of the thermoplastic polyimide resin. This is the thickness of the layer.

  The surface of the adhesive layer of the obtained film 1 is overlaid with the surface treated with the silane coupling agent of the stainless steel foil 2 of Preparation Example 2 and is subjected to a high-performance high-temperature vacuum press at 20 MPa, a temperature of 370 ° C., and a press time of 1 minute. A metal-clad laminate A1 was produced by thermocompression bonding. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2. The obtained metal-clad laminate had no particular problems with respect to adhesive strength and the shape of the insulating resin layer after etching. The adhesive strength of 0.5 kN / m or more was regarded as no problem.

A polyimide precursor resin solution B prepared by adding 458 g of DMAc to 42 g of the polyimide precursor resin b solution of Synthesis Example 2 and adjusting the solid content concentration to 1% by weight was prepared.
A polyimide film 2 having an adhesive layer and a metal-clad laminate B2 are produced in the same manner as in Example 1 except that the polyimide precursor resin solution B is used instead of the polyimide precursor resin solution A in Example 1. did. Note that almost 100% of the adhesive layer of the film 2 was an impregnated layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

A polyimide precursor resin solution C prepared by adding 458 g of DMAc to 42 g of the polyimide precursor resin c solution of Synthesis Example 3 and adjusting the solid content concentration to 1% by weight was prepared.
A polyimide film 3 having an adhesive layer and a metal-clad laminate C3 were prepared in the same manner as in Example 1 except that the polyimide precursor resin solution C was used instead of the polyimide precursor resin solution A in Example 1. did. Note that almost 100% of the adhesive layer of the film 3 was an impregnated layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

A polyimide precursor resin solution D prepared by adding 458 g of DMAc to 42 g of the polyimide precursor resin d solution of Synthesis Example 4 and adjusting the solid content concentration to 1% by weight was prepared.
A polyimide film 4 having an adhesive layer and a metal-clad laminate D4 are prepared in the same manner as in Example 1 except that the polyimide precursor resin solution D is used instead of the polyimide precursor resin solution A in Example 1. did. In addition, 90% or more of the adhesive layer of the film 4 was an impregnated layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

A polyimide precursor resin solution E prepared by adding 458 g of DMAc to 42 g of the polyimide precursor resin e solution of Synthesis Example 5 and adjusting the solid content concentration to 1 wt% was prepared.
A polyimide film 5 having an adhesive layer and a metal-clad laminate E5 are produced in the same manner as in Example 1 except that the polyimide precursor resin solution E is used instead of the polyimide precursor resin solution A in Example 1. did. In addition, 80% or more of the adhesive layer of the film 5 was the impregnated layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

A polyimide precursor resin solution F prepared by adding 458 g of DMAc to 42 g of the polyimide precursor resin f solution of Synthesis Example 6 to prepare a solid content concentration of 1% by weight was prepared.
A polyimide film 6 having an adhesive layer and a metal-clad laminate F6 were prepared in the same manner as in Example 1 except that the polyimide precursor resin solution F was used instead of the polyimide precursor resin solution A in Example 1. did. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. In addition, 80% or more of the adhesive layer of the film 6 was an impregnated layer. The results are shown in Table 2.

A polyimide precursor resin solution G prepared by adding 495 g of DMAc to 25 g of the polyimide precursor resin a solution of Synthesis Example 1 and adjusting the solid content concentration to 0.5% by weight was prepared.
A polyimide film 7 having an adhesive layer and a metal-clad laminate G7 are produced in the same manner as in Example 1 except that the polyimide precursor resin solution G is used instead of the polyimide precursor resin solution A in Example 1. did. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. Note that almost 100% of the adhesive layer of the film 7 was an impregnated layer. The results are shown in Table 2.

A polyimide precursor resin solution H prepared by adding 407 g of DMAc to 93 g of the polyimide precursor resin a solution of Synthesis Example 1 and adjusting the solid content concentration to 2% by weight was prepared.
A polyimide film 8 having an adhesive layer and a metal-clad laminate H8 are produced in the same manner as in Example 1 except that the polyimide precursor resin solution H is used instead of the polyimide precursor resin solution A in Example 1. did. Note that almost 100% of the adhesive layer of the film 8 was an impregnated layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

The polyimide film 1 having an adhesive layer obtained in Example 1 was used, and set in an RF magnetron sputtering apparatus (ANELVA; SPF-332HS) so that a metal raw material was formed on the adhesive layer surface of this film. Then, after reducing the pressure in the tank to 3 × 10 ⁻⁴ Pa, 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 I9. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

  A metal-clad laminate J10 was produced in the same manner as in Example 9 except that the polyimide film 4 having an adhesive layer obtained in Example 4 was used instead of the polyimide film 1 having an adhesive layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

  A metal-clad laminate K11 was produced in the same manner as in Example 9, except that the polyimide film 6 having an adhesive layer obtained in Example 6 was used instead of the polyimide film 1 having an adhesive layer. The adhesive strength between the film and the metal and the etching shape of the insulating resin layer were evaluated. The results are shown in Table 2.

Comparative Example 1
The polyimide film of Preparation Example 1 is overlaid with the silane coupling agent-treated surface of Stainless Steel Foil 2 of Preparation Example 2, and thermocompression bonded with a high-performance high-temperature vacuum press at 20 MPa, a temperature of 370 ° C., and a press time of 1 minute. Thus, a metal-clad laminate was produced. The adhesive strength between the film and the metal was less than 0.1 kN / m.

Comparative Example 2
In the same manner as in Example 1, except that the polyimide precursor resin solution a (solid content concentration 11% by weight) obtained in Synthesis Example 1 was used instead of the polyimide precursor resin solution A in Example 1, a metal was obtained. A tension laminate was produced. The adhesion strength between the film and the metal was 0.3 kN / m, and the shape of the insulating resin layer after etching was uneven.

Comparative Example 3
A polyimide precursor resin solution M prepared by adding 266 g of DMAc to 234 g of the polyimide precursor resin a solution obtained in Synthesis Example 1 to adjust the solid content concentration to 5% by weight was prepared.
A metal-clad laminate was produced in the same manner as in Example 1 except that the polyimide precursor resin solution M was used instead of the polyimide precursor resin solution A in Example 1. The adhesive strength between the film and the metal was 0.3 kN / m.

Comparative Example 4
The polyimide precursor resin solution M is used in place of the polyimide precursor resin solution A in Example 1, and the die coater 2 (discharge port height 20 μm) is used instead of the die coater (discharge port height 50 μm). A metal-clad laminate was prepared in the same manner as in Example 1 except that the polyimide precursor resin solution M was applied with a wet thickness of 20 μm. The adhesive strength between the film and the metal was 0.3 kN / m.

  The above results are summarized in Table 2. In Table 2, “resin solution” refers to the polyimide precursor resin solution used to form the adhesive layer, “precursor” refers to the type of polyimide precursor resin, and “concentration” refers to , Indicates the solid content concentration (% by weight) of the polyimide precursor resin solution, “adhesive layer” indicates the thickness (μm) of the adhesive layer after completing imidization, and “shape” indicates etching The shape of the subsequent insulating resin layer was shown, and the case where no irregularities were observed was evaluated as good.

Claims (7)

A method for producing a polyimide resin layer having an adhesive layer,
a) On the polyamic acid layer which is a precursor of a low thermal expansion polyimide resin having a thermal linear expansion coefficient of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), the solid content concentration is 0.1 weight. An impregnation layer forming step of applying a precursor solution of thermoplastic polyimide resin in a thickness of 1.0 to 3% by weight to impregnate a part or all of the solution into a polyamic acid layer;
b) It is provided with an adhesive layer forming step in which the polyamic acid layer on which the impregnated layer is formed is dried and imidized by heat treatment to form an adhesive layer having a thickness of less than 1.0 μm on the polyimide resin layer. A method for producing a polyimide resin layer having an adhesive layer. The method for producing a polyimide resin layer according to claim 1, wherein the precursor of the thermoplastic polyimide resin has a structural unit represented by the following formula (1).

(In formula (1), Ar ₁ represents a divalent aromatic group represented by formula (2), formula (3) or formula (4), and Ar ₂ represents formula (5) or formula (6). In the formulas (2) to (4) and (6), R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms. , N independently represents an integer of 0 to 4, and X and W independently represent a single bond or —C (CH ₃ ) ₂ —, — (CH ₂ ) m—, —O—, —S—, —CO—. , —SO ₂ —, —NH— or —CONH—, wherein m represents an integer of 1 to 5. And in 1 mol of Ar ₁ , — (CH ₂ ) m—, — 1 to 3 mol in total of divalent groups selected from O-, -S-, -CO-, -SO _2- , -NH- and -CONH- are included.) In formula (1), a divalent group selected from — (CH ₂ ) m—, —O—, —S—, —CO—, —SO ₂ —, —NH— and —CONH— in 1 mol of Ar ₂ The method for producing a polyimide resin layer according to claim 2, comprising a total of 0.4 to 0.8 mol of groups. In the formula (1),-(CH ₂ ) m-, -O-, -S-, -CO-, -SO _2- , -NH- and -CONH- are added in 2 mol of Ar ₁ and Ar ₂ in total. The method for producing a polyimide resin layer according to claim 2 or 3, comprising a total of 1.6 to 2.4 mol of selected divalent groups. The polyimide according to claim 2, which has a tetravalent aromatic group represented by formula (1), wherein Ar ₂ is represented by formula (6), and W is —SO ₂ —. Manufacturing method of resin layer. In the method for producing a metal-clad laminate,
I) an adhesive layer forming step of forming an adhesive layer on one side of the polyimide resin layer;
II) comprising a step of forming a metal layer on the surface of the adhesive layer, wherein step I) comprises:
a) On the polyamic acid layer which is a precursor of a low thermal expansion polyimide resin having a thermal linear expansion coefficient of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), the solid content concentration is 0.1 weight. An impregnation layer forming step of applying a precursor solution of thermoplastic polyimide resin in a thickness of 1.0 to 3% by weight to impregnate a part or all of the solution into a polyamic acid layer;
b) It is provided with an adhesive layer forming step in which the polyamic acid layer on which the impregnated layer is formed is dried and imidized by heat treatment to form an adhesive layer having a thickness of less than 1.0 μm on the polyimide resin layer. A method for producing a metal-clad laminate. Step II)
The method for producing a metal-clad laminate according to claim 6, further comprising: c) a step of superimposing a metal foil on the surface of the adhesive layer and thermocompression bonding; or d) a step of depositing a metal thin film layer on the surface of the adhesive layer.