JP2007186586A - Metallized polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallized polyimide film without containing factors giving a large effect to insulation property such as a sulfate ion, etc., usable for a flexible printed circuit having a fine wiring pattern and dealing with the requirements of downsizing, reduced weight and wiring in a high density of instruments. <P>SOLUTION: This metallized polyimide film is obtained by forming a metal layer having 0.5 to 5 μm thickness by a dry type film-forming method on at least one side surface of a polyimide film having 1 to 10 μm thickness, -5 to +25 ppm/°C range mean value of its linear expansion coefficient from 100°C to 350°C and also -0.20 to +0.12 ppm/°C<SP>2</SP>minimum value of differential linear expansion coefficient from 100°C to 350°C as above. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel flexible printed wiring board (FPC), a TAB, COF, COG, a metallized polyimide film used for a build-up layer material of a multilayer board using a film, an interposer, and the like. , Flexible printed wiring boards with miniaturized wiring patterns and multilayer boards using TAB, COF, COG, and films in response to miniaturization, weight reduction, and high-density wiring of electronic devices such as image display devices The present invention relates to a novel metallized polyimide film capable of producing materials for use, interposers and the like.

Along with technological advances in electronic devices such as mobile phones, the demand for build-up layers of multilayer substrates using FPC, TAB, COF, COG, and films has increased rapidly. Corresponding to the high density wiring, thinning of FPC and the like is progressing. For this reason, thinning of the FPC copper adhesive film (FCL) is also progressing at the same time. In particular, in order to make the wiring pattern fine, it is necessary to reduce the thickness of the copper layer.
As a conventional FPC, for example, there is a three-layer FPC composed of three layers of a polyimide film layer, an adhesive layer, and a copper layer. The three-layer FPC bonds a polyimide film and a copper foil through an adhesive. A three-layer flexible copper-clad laminate (metallized polyimide film) is produced, and the copper layer of the copper-clad laminate is etched to form a circuit. Since the adhesive layer exists in such a three-layer FPC, there is a limit to reducing the thickness. In addition, since an adhesive having inferior heat resistance, electrical properties, and mechanical strength is used as the adhesive layer as compared with the polyimide film, there is a problem that the properties of the polyimide film are not fully utilized.

As an FPC that compensates for the above-described drawbacks of the three-layer FPC, a two-layer FPC (for example, composed of a polyimide film layer and a copper layer) that does not have an adhesive layer has attracted attention and has been developed. Such a two-layer FPC can fully utilize the characteristics of the polyimide film because there is no adhesive layer, and can be made thinner than the three-layer FPC, improving the heat resistance and flexibility of the FPC. Made possible. This two-layer FPC can be manufactured by first preparing a flexible copper-clad laminate composed of two layers, a polyimide film layer and a copper layer, and etching the copper layer of the copper-clad laminate to form a circuit. it can. This two-layer flexible copper-clad laminate is a cast method in which polyamic acid varnish, which is a polyimide precursor, is applied to one side or both sides of a copper foil, followed by heat treatment and imidization, or copper foil and thermoplasticity. A laminating method in which a polyimide resin film is hot-pressed and produced by thermal fusion, a dry film-forming method in which a copper piece is heated and evaporated in a high vacuum to adhere to the polyimide film surface as a thin film, or a chemical in a plating solution It can be produced by an electroless plating method or a plating method (wet film forming method) in which copper is deposited on the surface of the polyimide film by a reduction reaction to form a copper layer.
However, in producing a copper clad laminate comprising two layers by the above method, there are the following problems due to the handling properties of the material (polyimide film or copper foil), and conventionally, the thickness of each material is 10 μm or less. I couldn't. When producing a two-layer flexible copper-clad laminate by the casting method, it is necessary to apply a polyamic acid varnish to one side of the copper foil, and the handling of the copper foil must be maintained. There is a problem that the thickness cannot be made 10 μm or less. On the other hand, when producing a two-layer flexible copper-clad laminate by a dry film-forming method such as a vapor deposition method or a wet film-forming method such as a plating method, the polyimide film surface is subjected to vapor deposition or plating. Sex must be maintained. Therefore, there has been a problem that the thickness of the polyimide film cannot be reduced.
It was difficult to produce a two-layer FPC having a polyimide film layer and a copper layer thickness of 10 μm or less, and further thinning of the FPC was a difficult problem.
In order to solve these problems, the initial tensile elasticity was achieved for the purpose of providing a flexible copper-clad laminate capable of producing an FPC excellent in flexibility and heat resistance by realizing further thinning of the two-layer FPC. A copper layer having a thickness of 10 μm or less is directly formed on one or both sides of a polyimide film having a thickness of 10 μm or less made of a polyimide polymer having a rate of 400 kg / mm ² or more (see Patent Document 1). However, although the mechanical strength of the thin polyimide film is regulated and the problem in handling is solved, the problem in the heat resistance behavior of the polyimide film in the direct copper layer formation in the dry film forming method such as vapor deposition and sputtering, for example At realistic deposition rates, film thermal deformation such as warp and wrinkles due to thermal shrinkage and thermal expansion of the film, and film alteration, or Corruption occurs, also, in which problems may remain in peeling between the copper layer. Also, in order to provide a flexible printed wiring board with high adhesion between layers, excellent heat resistance, chemical resistance, bending resistance and electrical characteristics, and high reliability even in high-density wiring, one or both sides of plastic film In addition, a flexible print is formed by sequentially laminating a vapor deposition layer of chromium, a chromium alloy or a chromium-based ceramic, and an electron beam heating vapor deposition copper layer composed of an aggregate having a deposited particle size in the range of 0.007 to 0.850 μm. Although a wiring substrate (see Patent Document 2) has been proposed, it has solved the problems in terms of heat resistance, chemical resistance, bending resistance and electrical characteristics, but as described above, vapor deposition and sputtering, Issues in heat resistance behavior of polyimide film in direct copper layer formation by dry film forming methods such as electron beam heating vapor deposition, for example, due to thermal shrinkage and thermal expansion of the film Thermal deformation of the film such Riyashiwa, and alteration of the film, or problems in peeling of damage or copper layer is one that it can not be said that a sufficiently resolved.
Japanese Patent Laid-Open No. 08-156176 JP 05-259595 A

  The present inventors have solved the above problems, realized further thinning of the FPC, reduced the size and weight of the electronic device, and refined the wiring pattern in response to higher density wiring, flexibility and heat resistance Results of extensive research aimed at providing a metallized polyimide film that can be used to fabricate build-up layer materials, interposers, etc. for multi-layer boards using FPC, TAB, COF, COG, and films. The polyimide film with specific physical properties that can sufficiently withstand the heat generated by the dry film-forming method is suitable for miniaturization of wiring, has sufficient heat resistance and handling properties, and has high insulation properties such as sulfate ions. The present inventors have found that it is a metallized polyimide film that does not contain an influencing factor, and have reached the present invention.

As a result of intensive studies, the present inventors have found that a polyimide film having specific physical properties has sufficient adhesion strength with a metal layer such as copper and should satisfy the metallized film production in the thermal behavior in the dry film forming method. It is a dry film-forming method that does not include factors that greatly affect insulation properties such as sulfate ions when a copper layer is formed by a wet film-forming method by using a thin film of this polyimide film. Ultra-thin metallized polyimide, which can directly form a thin film of copper, etc., can be made into a metallized polyimide film that can contribute to miniaturization and power saving, has sufficient adhesion to the metal layer, and has very little wrinkling and peeling It is a highly reliable wiring board that can hold the film and the resulting conductive pattern with sufficient adhesive strength and withstand the heat history of cooling and heating. It found that it was arrived at the present invention.
That is, this invention consists of the following structures.
1. The thickness is 1 to 10 μm, the average value of the linear expansion coefficient from 100 ° C. to 350 ° C. is in the range of −5 to +25 ppm / ° C., and the minimum value of the differential linear expansion coefficient from 100 ° C. to 350 ° C. is −0. A metallized polyimide film, wherein a metal layer having a thickness of 0.5 to 5 μm formed by a dry film-forming method is formed on at least one surface of a polyimide film of 20 to +0.12 ppm / ° C. ² .
2. 2. The metallization according to 1 above, wherein the polyimide film is a polyimide film obtained by reacting a diamine having a benzoxazole structure with a diamine and a tetracarboxylic acid in the range of 10 to 100 mol% of the total diamine. Polyimide film.
3. 3. The metallized polyimide film as described in 1 or 2 above, wherein the metal layer is mainly composed of copper.

The thickness of the present invention is 1 to 10 μm, the average value of linear expansion coefficient from 100 ° C. to 350 ° C. (hereinafter also referred to as CTE) is in the range of −5 to +25 ppm / ° C., and the differential line from 100 ° C. to 350 ° C. A metal layer having a thickness of 0.5 to 5 μm formed by a dry film-forming method on at least one surface of a polyimide film having a minimum expansion coefficient (hereinafter also referred to as dCTE) of −0.20 to +0.12 ppm / ° C. ² The metallized polyimide film on which no is formed does not cause poor insulation or deterioration of insulation due to residual chemicals in wet plating or electroless plating, and does not have adverse effects on the environment of chemicals used for plating. , Flexible printed wiring boards with miniaturized wiring patterns that can support miniaturization, weight reduction, and high-density wiring, and TAB, COF, COG, Be a novel metallized polyimide film may be produced such as build-up layer material of the multilayer substrate using the Lum, industrial significance is extremely large.

The polyimide film in the metallized polyimide film of the present invention has a thickness of 1 to 10 μm, an average value of linear expansion coefficient (CTE) from 100 ° C. to 350 ° C. is in the range of −5 to +25 ppm / ° C., and 100 if polyimide film minimum value of the differential coefficient of linear expansion (dCTE) is -0.20~ + 0.12ppm / ℃ ² at ° C. 350 ° C. from, but is not particularly limited.
In the present invention, the minimum value (dCTE) of the differential linear expansion coefficient from 100 ° C. to 350 ° C. is a differential coefficient of the linear expansion coefficient in a plot of each linear expansion coefficient with respect to each temperature from 100 ° C. to 350 ° C.
Therefore, the minimum value of the differential coefficient of linear expansion 350 ° C. from 100 ° C. In the present invention (dCTE) is -0.20~ + 0.12ppm / ℃ ² is linear expansion coefficient for each temperature at 350 ° C. from 100 ° C. This means that the slope does not drop rapidly. Rapid change in linear expansion coefficient with respect to temperature change, such as the minimum value of the differential coefficient of linear expansion is less than -0.20ppm / ℃ ² at 350 ° C. from 100 ° C., the adhesion of the film and the metal layer when laminating a metal thin film The metal thin film layer may be peeled off or wrinkled. On the other hand, when the change of the linear expansion coefficient with respect to the temperature change is small, when the metal thin film is laminated, sufficient adhesion can be obtained, and peeling of the metal thin film layer and generation of wrinkles can be extremely suppressed. If the minimum value of the differential linear expansion coefficient from 100 ° C to 350 ° C exceeds +0.12, the average value (CTE) of the linear expansion coefficient from 100 ° C to 350 ° C cannot be made in the range of -5 to +25 ppm / ° C. When the metal thin film is laminated, the adhesion between the film and the metal layer becomes insufficient, and the metal thin film layer may be peeled off or wrinkled.

The plots of Comparative Example 1 and Comparative Example 2 in FIG. 1 have clear peaks and valleys, and the differential linear expansion coefficient (dCTE) from 100 ° C. to 350 ° C. has a large negative value. On the other hand, the plots of the examples depict a gradually increasing plot in which the differential linear expansion coefficient (dCTE) from 100 ° C. to 350 ° C. is slightly on the plus side from 0.
Such a polyimide film is obtained, for example, by reacting a diamine with a tetracarboxylic acid, preferably a tetracarboxylic acid anhydride.

The above “reaction” is not particularly limited, but preferably a diamine and a tetracarboxylic acid anhydride are subjected to a ring-opening polyaddition reaction in a solvent to obtain a polyamic acid solution, and then the polyamic acid solution From a self-supporting film (hereinafter also referred to as a polyimide precursor film or a green film), followed by dehydration condensation (imidization).
In the present invention, a polyamic acid solution (A) obtained by reacting an aromatic diamine having a benzoxazole structure with a tetracarboxylic acid, an aromatic diamine having no benzoxazole structure, and an aromatic tetracarboxylic acid And the polyamic acid solution (B) obtained by reacting with A: B in a molar ratio of 30-100: 70-0, preferably A: B in a molar ratio of 50-100: 50-0. Then, the mixed solution is applied and cast on a support, dried to obtain a self-supporting film (green film), and the green film is heat-treated in a range of 150 ° C. to 500 ° C. to form a ring-closure imidization. The method of forming a polyimide film is preferably employed.

By using the above-mentioned specific diamine within a predetermined range, a polyimide film having specific linear expansion coefficient characteristics of the present invention can be easily obtained, and when outside the predetermined range, these specific linear expansion coefficient characteristics and mechanical properties are obtained. It becomes difficult to produce a polyimide film having strength, high rigidity, and strength.
In the present invention, aromatic diamines having a benzoxazole structure are preferably used at a predetermined ratio.

  Specific examples of aromatic diamines having a benzoxazole structure that are preferably used at a predetermined ratio of the present invention include the following.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.
In the present invention, the following aromatic diamine may be used in addition to the diamine.
Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'- Diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1 , 1-Bi [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] propane, 1 , 2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ]propane,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3 Aminophenoxy) benzoyl] benzene, 4,4′-bis [4- (3-aminophenoxy) benzoyl] biphenyl, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [ 4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis 4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3 -Bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl Benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] benzonitrile and some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or alkyl groups or alkoxyl group hydrogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms, partially or entirely substituted with halogen atoms, or alkoxyl groups.

  The tetracarboxylic acids used in the present invention are preferably aromatic tetracarboxylic anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following. Among them, pyromellitic anhydride of Chemical Formula 4 can be preferably used, and this pyromellitic acid anhydride is 70 mol% or more, more preferably 90 mol% or more of all tetracarboxylic acids.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.
In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are less than 30 mol% of the total tetracarboxylic dianhydrides. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride,

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when polymerizing diamines and tetracarboxylic acid anhydrides to obtain polyamic acid is not particularly limited as long as it dissolves both the raw material monomer and the polyamic acid to be produced. Organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphos Examples include hollic amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 30% by mass.

Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for min-70 hours. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited. For example, it is preferable to add aromatic tetracarboxylic acid anhydrides to a solution of aromatic diamines. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 2.0 dl / g or more, more preferably 3.0 dl / g or more, and still more preferably 4.0 dl / g or more. preferable.

Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.
In order to form a polyimide film from the polyamic acid solution obtained by the polymerization reaction, a green film is obtained by coating the polyamic acid solution on a support and drying, and then subjecting the green film to a heat treatment. A method of imidization reaction may be mentioned.

  The support on which the polyamic acid solution is applied is only required to have smoothness and rigidity sufficient to form the polyamic acid solution into a film, and a drum or belt whose surface is made of metal, plastic, glass, porcelain, etc. And the like. Among them, the surface of the support is preferably a metal, more preferably stainless steel that does not rust and has excellent corrosion resistance. The surface of the support may be plated with metal such as Cr, Ni, or Sn. The surface of the support can be made into a mirror surface as needed, or can be processed into a satin finish. Application of the polyamic acid solution to the support includes, but is not limited to, casting from a slit base, extrusion through an extruder, squeegee coating, reverse coating, die coating, applicator coating, wire bar coating, etc. Conventionally known solution coating means can be appropriately used.

  When the green film is dried to such an extent that self-supporting properties can be obtained, a green film can be obtained in which the imidation ratio of the front and back surfaces and the difference thereof are within a predetermined range by controlling the amount of residual solvent relative to the total mass after drying. . Specifically, the amount of residual solvent with respect to the total mass after drying is preferably 25 to 50% by mass, more preferably 35 to 50% by mass. When the residual solvent amount is lower than 25% by mass, the imidization rate on one side of the green film becomes relatively high, and it becomes difficult to obtain a green film with a small difference in imidization rate between the front and back surfaces. In addition, the green film tends to become brittle due to a decrease in molecular weight. Moreover, when it exceeds 50 mass%, self-supporting property becomes inadequate and conveyance of a film becomes difficult in many cases.

  As drying conditions for obtaining a green film in which the amount of residual solvent relative to the total mass after drying is within a predetermined range, for example, when N-methylpyrrolidone is used as a solvent, the drying temperature is preferably 70 to 130 ° C., More preferably, it is 75-125 degreeC, More preferably, it is 80-120 degreeC. When the drying temperature is higher than 130 ° C., the molecular weight is lowered and the green film tends to be brittle. In addition, imidization partially proceeds during the production of the green film, and it becomes difficult to obtain desired physical properties during the imidization process. On the other hand, when the temperature is lower than 70 ° C., the drying time becomes long, the molecular weight tends to decrease, and the handling property tends to be poor due to insufficient drying. The drying time is preferably 10 to 90 minutes, more preferably 15 to 80 minutes, although it depends on the drying temperature. When the drying time is longer than 90 minutes, the molecular weight is lowered and the film tends to be brittle. When the drying time is shorter than 10 minutes, the drying property is insufficient and the handling property tends to be poor. Further, in order to improve the drying efficiency or suppress the generation of bubbles at the time of drying, the temperature may be raised stepwise in the range of 70 to 130 ° C. for drying.

A conventionally known drying apparatus that achieves such conditions can be applied, and examples thereof include hot air, hot nitrogen, far infrared rays, and high frequency induction heating.
In the case of performing hot air drying, when the green film is dried to such an extent that self-supporting property is obtained, the range of the imidization ratio on the front and back surfaces of the green film and the difference thereof are set within a predetermined range. It is preferable to control the temperature difference to 10 ° C. or less, preferably 5 ° C. or less, and it is necessary to control the temperature difference by individually controlling the hot air temperature on the upper surface / lower surface.

As a method for imidizing the green film, a conventionally known imidization reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or the polyamic acid solution contains a ring-closing catalyst and a dehydrating agent. In order to obtain a polyimide film in which the difference in surface orientation between the front and back surfaces of the polyimide film is small, a chemical ring closing method can be mentioned in which an imidization reaction is performed by the action of the above ring closing catalyst and dehydrating agent. The thermal ring closure method is preferred.
The maximum heating temperature of the thermal ring closure method is about 100 to 500 ° C, preferably 200 to 480 ° C. When the maximum heating temperature is lower than this range, it is difficult to close the ring sufficiently, and when it is higher than this range, deterioration proceeds and the film tends to become brittle. A more preferable embodiment includes a two-stage heat treatment in which treatment is performed at 150 to 250 ° C. for 3 to 20 minutes and then treatment is performed at 350 to 500 ° C. for 3 to 20 minutes.

In the chemical ring closure method, after the polyamic acid solution is applied to a support, the imidization reaction is partially advanced to form a self-supporting film, and then imidization can be performed completely by heating. In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes.
The timing for adding the ring-closing catalyst to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and betapicoline. Among them, heterocyclic tertiary amines are mentioned. At least one amine selected from is preferred. Although the usage-amount of a ring-closing catalyst with respect to 1 mol of polyamic acids does not have limitation in particular, Preferably it is 0.5-8 mol.

  The timing of adding the dehydrating agent to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among them, acetic anhydride, benzoic anhydride, etc. Acids or mixtures thereof are preferred. Moreover, the usage-amount of the dehydrating agent with respect to 1 mol of polyamic acids is although there is no limitation in particular, Preferably it is 0.1-4 mol. When a dehydrating agent is used, a gelation retarder such as acetylacetone may be used in combination.

Whether it is a thermal cyclization reaction or a chemical cyclization method, the polyimide film precursor (green film) formed on the support may be peeled off from the support before it is completely imidized. You may peel after conversion.
Although the thickness of a polyimide film is not specifically limited, When considering using it for the base substrate for printed wiring boards mentioned later, it is 1-150 micrometers normally, Preferably it is 3-50 micrometers. This thickness can be easily controlled by the amount of the polyamic acid solution applied to the support and the concentration of the polyamic acid solution.
The thermal ring closure method is a method in which polyamic acid is imidized by heating. The polyamic acid solution may contain a ring closing catalyst and a dehydrating agent, and the imidization reaction may be promoted by the action of the ring closing catalyst and the dehydrating agent. In this method, after the polyamic acid solution is applied to the support, the imidization reaction is partially advanced to form a film having self-supporting property, and then imidization can be performed completely by heating.
The timing for adding the ring-closing catalyst to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and betapicoline. Among them, heterocyclic tertiary amines are mentioned. At least one amine selected from is preferred. Although the usage-amount of a ring-closing catalyst with respect to 1 mol of polyamic acids does not have limitation in particular, Preferably it is 0.5-8 mol.

The timing of adding the dehydrating agent to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among them, acetic anhydride, benzoic anhydride, etc. Acids or mixtures thereof are preferred. Moreover, the usage-amount of the dehydrating agent with respect to 1 mol of polyamic acids is not particularly limited, but is preferably 0.1 to 4 mol. When a dehydrating agent is used, a gelation retarder such as acetylacetone may be used in combination.
The polyimide film precursor (green film) formed on the support may be peeled off from the support before complete imidization, or may be peeled off after imidization.

The polyimide film of the present invention is preferably provided with a lubricant in the polyimide to give fine irregularities on the film surface to improve the slipping property of the film.
As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 μm to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.
The polyimide film of the present invention is usually an unstretched film, but may be stretched uniaxially or biaxially. Here, the unstretched film refers to a film obtained without intentionally applying a mechanical external force in the surface expansion direction of the film by tenter stretching, roll stretching, inflation stretching, or the like.

  In the metallized polyimide film of the present invention, it is obtained by forming a metal layer such as copper on the heat-resistant polyimide film having the specific physical properties by a dry film forming method, but as a dry film forming method, a chemical solution is used. The dry film forming method is not particularly limited as long as it is a dry film forming method, and examples thereof include a sputtering method, a resistance heating vapor deposition method, an electron beam heating vapor deposition method, a CVD method, an ion plating method, and a thermal spraying method. From the viewpoint of metal layer formation efficiency, the resistance heating evaporation method and the electron beam heating evaporation method are preferable, and the electron beam heating evaporation method is particularly preferable.

In the present invention, the surface treatment may be performed before the metal layer is formed on the surface of the polyimide film. For example, when the metal layer is laminated on one side or both sides of the surface-treated polyimide film, the base metal layer is previously formed. The metal used as the base metal layer may be formed to strengthen the adhesion with the polyimide film, no diffusion, chemical resistance and heat resistance. Good characteristics are important characteristics, and copper, nickel, chromium, chromium alloy, chromium-based ceramic, monel alloy, TiN, and Mo-containing Cu are preferable. Examples of chromium alloys include alloys containing manganese, nickel, cobalt, silicon, titanium, vanadium, carbon, molybdenum, and tungsten, and examples of chromium-based ceramics include Cr ₂ O ₃ .
The base metal layer described above is preferably one or more selected from the group consisting of chromium, a chromium alloy, a chromium-based ceramic monel alloy, TiN, and Mo-containing Cu on one or both surfaces of a plastic film that has been subjected to a surface treatment, for example. Is deposited by sputtering or ion plating to form a base metal layer. In this case, a sputtering method that improves processing stability, simplifies the process, improves the uniformity of the deposited layer, and reduces the occurrence of curling is more preferable.

The film thickness of the base metal layer is preferably in the range of 10 to 500 mm, more preferably in the range of 10 to 40 mm.
A main metal layer such as copper can be provided on the base metal layer or directly on the polyimide film, but the metal of the main metal layer is not particularly limited as long as it is a highly conductive metal, and gold, silver Aluminum, copper, indium, tin and the like can be mentioned, but copper or a copper alloy containing copper as a main component can be preferably used in view of economy and conductivity.
The formation method of these main metal layers may be the dry film formation method described above, but is preferably a vapor deposition method, and the film thickness (layer thickness) of this main metal layer is in the range of 0.5 μm to 5 μm. The range of 1 to 4 μm is more preferable. If the film thickness is less than 0.5 μm, various performances when the wiring is formed are deteriorated, and if it exceeds 5 μm, the cost increases and the effect of reducing the thickness of the film is reduced.
The metallized polyimide film of the present invention can be used very effectively as, for example, an FPC (flexible printed wiring board), but the FPC from the metallized polyimide film of the present invention is excellent in light and thin film formation and is flexible. A flexible printed wiring board rich in properties can be obtained, and a highly accurate wiring circuit can be formed.

Although the temperature at the time of metal layer formation in this invention is not specifically limited, It is suitable to set it as 100-350 degreeC.
The degree of vacuum at the time of forming the metal layer is set to a high vacuum of 5 × 10 ⁻⁵ Torr or less in advance, and after maintaining a high vacuum of 5 × 10 ⁻⁶ Torr or less, a high vacuum with a gas pressure of 5 × 10 ⁻³ Torr or less The metal layer is preferably formed while maintaining a high vacuum of 5 × 10 ⁻⁴ Torr or less. For example, nitrogen, hydrogen, and oxygen can be adopted as the gas species used during sputtering in addition to rare gases such as argon, neon, krypton, and helium, but argon and nitrogen are preferable because they are inexpensive.
From the viewpoint of reducing productivity and thermal damage to the film, the traveling speed of the film at the time of forming the metal layer is preferably in the range of 0.5 to 20 m / min, and 1.0 to 10 m / min. A range is more preferred. When the speed is less than 0.5 m / min, productivity is lowered, and the film is easily influenced by radiant heat during evaporation, which is not preferable. On the other hand, if it exceeds 20 m / min, the formed metal layer is not uniform, which is not preferable.

An inorganic coating film such as a single metal or a metal oxide may be formed on the surface of the metal layer used in the present invention. Further, the surface of the metal layer may be subjected to treatment with a coupling agent (aminosilane, epoxysilane, etc.), sand plast treatment, hole treatment, corona treatment, plasma treatment, etching treatment, and the like. Similarly, the surface of the polyimide film may be subjected to honing treatment, corona treatment, plasma treatment, etching treatment, and the like. In the plasma treatment, oxygen, argon, nitrogen, CF ₄ , hydrogen, or a mixed gas thereof is desirable as a gas to be used. More desirable are oxygen gas and nitrogen gas. In addition to vacuum plasma, plasma at atmospheric pressure may be used as the pressure at the time of processing.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 25 ° C. with an Ubbelohde type viscosity tube.
(When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved and measured using N, N-dimethylacetamide.)

2. The thickness of the polyimide film The thickness was measured using a micrometer (Millitron 1254D manufactured by Fine Reef).

3. Specimen obtained by cutting a polyimide film to be measured into a strip of 100 mm × 10 mm in the flow direction (MD direction) and the width direction (TD direction), respectively. It was. Using a tensile tester (manufactured by Shimadzu Corporation, Autograph (trade name), model name AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile modulus of elasticity in each of the MD direction and TD direction, Tensile rupture strength and tensile rupture elongation were measured.

4). The linear expansion coefficient and the differential linear expansion coefficient of the polyimide film (a) For the polyimide film to be measured, the expansion and contraction rates in the MD direction and the TD direction are measured under the following conditions, and 30 ° C to 40 ° C, 40 ° C to 50 ° C, ... The stretch rate / temperature at intervals of 10 ° C. was measured, this measurement was performed up to 400 ° C., and the average value of all measured values from 100 ° C. to 350 ° C. was calculated as CTE (average value). The meanings of the MD direction and the TD direction are the same as in the measurement of “3.” above.
(B) About the polyimide film of a measuring object, the expansion / contraction rate of MD direction and TD direction was measured on the following conditions, and the expansion / contraction rate / temperature in the interval of 30 to 40 degreeC, 40 to 50 degreeC, ... and 10 degreeC. This measurement was performed up to 400 ° C., and the differential linear expansion coefficient from 100 ° C. to 350 ° C. was calculated by subjecting all measured values from 100 ° C. to 350 ° C. to differential calculation processing with respect to temperature. The outline is shown in FIG. 1 and FIG. The minimum value in Examples and Comparative Examples indicates the minimum value of the differential linear expansion coefficient in the MD direction and TD direction in this temperature range.
Device name: TMA4000S manufactured by MAC Science
Sample length; 10mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

5). Peeling of the laminated metal layer and wrinkle At least 0.3 m of the obtained metal layer laminated polyimide film was collected and allowed to stand on a horizontal surface, and the peeling of the metal thin film layer and wrinkles were visually observed, and almost no peeling and wrinkle occurred. ◎ was observed, △ was observed when peeling and wrinkles were slightly observed, and X was determined when peeling and wrinkles were observed.

[Reference Example 1]
<Polymerization of polyamic acid-1>
<Polymerization of a polyamic acid composed of a diamine having a benzoxazole structure>
The inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, and then 500 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole was charged. Next, after 8000 parts by mass of N, N-dimethylacetamide was added and completely dissolved, 485 parts by mass of pyromellitic dianhydride was added and stirred at a reaction temperature of 25 ° C. for 48 hours. A polyamic acid solution (A) was obtained. The solution obtained had a ηsp / C of 4.0 dl / g.

[Reference Example 2]
<Polyamide acid polymerization-2>
Pyromellitic anhydride 545 parts by weight, 4,4 ′ diaminodiphenyl ether 500 parts by weight are dissolved in 8000 parts by weight of N, N-dimethylacetamide and reacted in the same manner while maintaining the temperature at 20 ° C. or lower to obtain a polyamic acid solution ( B-1) was obtained. The ηsp / C of the obtained solution was 2.2 and was dl / g.

[Reference Example 3]
<Polyamide acid polymerization-3>
As a tetracarboxylic dianhydride, 398 parts by mass of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 147 parts by mass of paraphenylenediamine are dissolved in 4600 parts by mass of N, N-dimethylacetamide, and the temperature is increased. Was kept in a temperature of 20 ° C. or lower in the same manner to obtain a polyamic acid solution (B-2). The obtained solution had a ηsp / C of 3.0 dl / g.

[Examples 1-5, Comparative Examples 1-2]
The polyamic acid solutions obtained in each reference example were mixed in the ratios shown in Tables 1 and 2, and this mixed polyamic acid solution was 600 mm wide using a comma coater, and the coating film dry thickness was 14 μm on one side of an endless stainless steel belt. The film is dried and peeled off at 110 ° C. for 60 minutes to obtain a green film as each polyimide precursor film, and this green film is passed through a continuous heat treatment furnace purged with nitrogen. The imidization reaction was advanced by applying two-stage high temperature heating in the second stage.
Then, the polyimide film of each example which exhibits brown was obtained by cooling to room temperature in 5 minutes. The measurement results of the obtained polyimide film are shown in Tables 1 and 2.

(Preparation of sputtered base metal layer film)
The film obtained in each of the above examples was set in a vacuum apparatus having a sputtering apparatus equipped with an unwinding apparatus, a winding apparatus, a plasma processing apparatus, and two targets, and then the film surface was plasma-treated while feeding the film. Went. The plasma treatment conditions are oxygen gas, frequency 13.56 MHz, output 90 W, gas pressure 0.9 Pa, and the temperature during the treatment is not particularly controlled. The residence time in the plasma atmosphere was about 20 seconds.
Next, the plasma-treated film is evacuated to an output of 800 W and an ultimate vacuum of 2 × 10 ⁻⁴ Pa in the sputtering area, and then introduced with argon gas, under conditions of argon gas pressure of 0.5 Pa, nickel -A nickel-chromium alloy film was formed by DC magnetron sputtering under an argon atmosphere using a chromium (chrome 12%) target. Subsequently, a 3000 angstrom copper thin film was formed by sputtering using a copper target, and a thin film production example 1 was obtained. The film during sputtering is in contact with a chill roll whose temperature is controlled at 5 ° C.

(Preparation of electron beam evaporated metal thin film)
Each film on which the sputtering base metal layer film was produced was set in a vacuum apparatus having an unwinding apparatus, a winding apparatus, a plasma processing apparatus, and electron beam evaporation. First, the surface of the sputtering underlayer was plasma treated while feeding the film. The plasma treatment conditions are oxygen gas, frequency 13.56 MHz, output 90 W, gas pressure 0.9 Pa, and the temperature during the treatment is not particularly controlled. The residence time in the plasma atmosphere was about 20 seconds. At this time, the oxide layer on the sputtering thin film was removed by the plasma treatment, and the sputtering base metal layer film was not significantly removed.
Next, a copper layer was deposited on the film after the plasma treatment by electron beam evaporation. After evacuation to an ultimate vacuum of 5 × 10 ⁻⁴ Pa, electron beam evaporation was performed.
In the vacuum tank of this apparatus, the base film unwound from the unwinding roll is supplied to the chill roll through the guide roll. Then, this base film is wound up on a winding roll through a guide roll. A hole is provided in the deposition preventing plate. The “crucible” is located at a location facing the chill roll across the hole portion of the high-frequency voltage application electrode and the deposition preventing plate. The evaporation source material filled in the “crucible” is heated to become vapor. The vapor passes through the holes and is deposited on the substrate film on the surface of the chill roll to form a desired thin film.
The peeling and wrinkle of the copper thin film layer in the copper thin film layer laminate of each polyimide film were evaluated. The results are shown in Tables 1, 2, and 3.

(Pattern production)
A photosensitive resist was laminated on the copper foil surface of the flexible metal-clad laminate, exposed and baked with a mask film, developed, and a “comb pattern” as shown in FIG. 3 was transferred as a necessary pattern. Here, the conductor width and the conductor interval were two types of 1 μm / 1 μm and 5 μm / 5 μm, and the pattern overlap was 15.75 mm. The number of patterns was 20 on one side and 21 on the other side. Next, the copper foil was removed by etching using a 35% cupric chloride solution at 40 ° C., and the resist used for circuit formation was removed with alkali to perform circuit processing.
The quality of the pattern was observed with an optical microscope, and then a test according to the HAST test method was performed. The applied voltage is 0.5 VDC, the measurement interval is 1 time, and the insulation is 60 minutes.
The quality of the copper thin film layer pattern in the copper thin film layer laminate of each polyimide film and the HAST test were evaluated. Resistance measurement device JIS C1303 specified product, test conditions 110 ° C., 85% RH, 400 hours. The results are shown in Tables 1, 2, and 3.
In addition, about the film of thickness 5 micrometers and 3 micrometers, PET film with an adhesive was stuck on the surface to vapor-deposit and the opposite surface, and sputtering and electron beam vapor deposition were performed. By doing in this way, it was prevented that a film turns into a wrinkle at the time of roll conveyance, and a slip generate | occur | produces at the time of conveyance.
As Comparative Examples 3 and 4, materials having different film thicknesses by electron beam evaporation were prepared. As Comparative Examples 5, 6, and 7, electrolytic plating was performed after the production of the sputtering base film.
The plating was copper sulfate plating. Immerse in an electrolytic plating solution (copper sulfate 80 g / l, sulfuric acid 210 g / l, HCl, a small amount of brightener), use a phosphor-containing copper plate for the anode, and pass a current of 1.5 Adm ² while stirring the plating solution by bubbling. A copper layer was prepared. The results are shown in Table 4.

In the column of tensile breaking strength to linear expansion coefficient (average value), the upper row shows values in the MD direction, and the lower row shows values in the TD direction.

In the column of tensile breaking strength to linear expansion coefficient (average value), the upper row shows values in the MD direction, and the lower row shows values in the TD direction.

A thin film production example 2 was obtained in the same manner as the thin film production example 1 except that a TiN target was used instead of the nickel-chromium (chromium 12%) target as the base metal layer.
A thin film preparation example 3 is performed in the same manner as in the thin film preparation example 1 except that a target obtained by adding a small amount of molybdenum (Mo) to copper (Cu) is used as the base metal layer instead of the nickel-chromium (chromium 12%) target. Obtained.
A thin film production example 4 was obtained in the same manner as in the thin film production example 1 except that a monel alloy target was used instead of the nickel-chromium (chromium 12%) target as the base.
(The target composition at this time is Ni: 66.0, C: 0.12, Mn: 0.9, Fe: 1.35, S: 0.005, Si: 0.15, Cu: 31.5. (It was mass%.)
For these thin film production examples 2, 3, and 4, as in the above examples and comparative examples, the film composition, the film thickness, the thickness of the electron beam evaporated copper, and the conductor width / conductor spacing of the pattern were changed. However, similar results were obtained.

The average linear expansion coefficient (CTE) of 100 to 350 ° C. in the range of −5 to +25 ppm / ° C. and the differential linear expansion coefficient from 100 to 350 ° C. A metal layer having a thickness of 0.5 μm to 5 μm formed by a dry film forming method on at least one side of a polyimide film having a minimum value (dCTE) of −0.20 to +0.12 ppm / ° C. ² The polyimide film is a metalized polyimide film that does not contain factors that greatly affect insulation properties such as sulfate ions, and the wiring pattern that can be used for miniaturization, weight reduction, and high-density wiring of equipment is fine. Effectively used for built-up flexible printed wiring boards, TAB, COF, COG, materials for build-up layers of multilayer boards using films, etc. Industrial significance can is extremely large.

Plot of linear expansion coefficient for each temperature of polyimide film from 100 ° C to 350 ° C Plot of each differential linear expansion coefficient with respect to each temperature from 100 ° C. to 350 ° C. of the polyimide film (Examples 1 and 2) Plot diagram of each differential linear expansion coefficient with respect to each temperature from 100 ° C. to 350 ° C. of the polyimide film (Examples 3 and 4) Plot diagram of each differential linear expansion coefficient with respect to each temperature at 100 ° C. to 350 ° C. of the polyimide film (Comparative Examples 1 and 2) Figure showing an example of comb pattern

Claims (3)

The thickness is 1 to 10 μm, the average value of the linear expansion coefficient from 100 ° C. to 350 ° C. is in the range of −5 to +25 ppm / ° C., and the minimum value of the differential linear expansion coefficient from 100 ° C. to 350 ° C. is −0. A metallized polyimide film, wherein a metal layer having a thickness of 0.5 to 5 μm formed by a dry film-forming method is formed on at least one surface of a polyimide film of 20 to +0.12 ppm / ° C. ² .   2. The metal according to claim 1, wherein the polyimide film is a polyimide film obtained by reacting a diamine having a benzoxazole structure with a diamine in the range of 10 to 100 mol% of the total diamine and a tetracarboxylic acid. Polyimide film.   The metallized polyimide film according to claim 1, wherein the metal layer is a layer containing copper as a main component.