JP6767751B2 - Polyamic acid, polyimide, resin film and metal-clad laminate - Google Patents

Description

The present invention relates to a polyamic acid, a polyimide, and a resin film and a metal-clad laminate using the polyimide.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, a flexible printed wiring board (FPC; Flexible Printed Circuit Board) (FPC), which is thin and lightweight, has flexibility, and has excellent durability even after repeated bending. The demand for Circuits) is increasing. Since FPC can be mounted three-dimensionally and at high density even in a limited space, it can be used for wiring of moving parts of electronic devices such as HDDs, DVDs, and mobile phones, and for parts such as cables and connectors. It is expanding.

In addition to the above-mentioned high density, the high performance of the equipment has advanced, so it is also necessary to cope with the high frequency of the transmission signal. When a high-frequency signal is transmitted, if the transmission loss of the signal transmission path is large, inconveniences such as loss of an electric signal and long delay time of the signal occur. Therefore, it is important to reduce the transmission loss of the FPC. In order to cope with high frequency, an FPC having a liquid crystal polymer having a low dielectric constant and a low dielectric loss tangent as a dielectric layer is used. However, although the liquid crystal polymer has excellent dielectric properties, there is room for improvement in heat resistance and adhesiveness to the metal foil.

In order to improve heat resistance and adhesiveness, a metal-clad laminate having a polyimide as an insulating layer has been proposed (Patent Document 1). According to Patent Document 1, it is generally known that the dielectric constant is lowered by using an aliphatic monomer as the monomer of the polymer material, and an aliphatic (chain) tetracarboxylic dianhydride is used. Since the heat resistance of the obtained polyimide is extremely low, it cannot be used for processing such as soldering, which poses a practical problem. However, when an aliphatic tetracarboxylic dianhydride is used, it becomes a chain. It is said that a polyimide with improved heat resistance can be obtained. However, although the polyimide film formed from such a polyimide has a dielectric constant of 3.2 or less at 10 GHz, the dielectric loss tangent is more than 0.01, and the dielectric property is still not sufficient. In addition, many of the polyimides using the above-mentioned aliphatic monomers have a large coefficient of thermal expansion, and a metal-clad laminate having these as an insulating layer causes warpage, so that it is difficult to use the polyimide as an insulating layer of a circuit board. It was.

Japanese Unexamined Patent Publication No. 2004-358961

An object of the present invention is to provide a polyimide, a resin film, and a metal-clad laminate, which can cope with high frequency due to miniaturization and high performance of electronic devices and have a low coefficient of thermal expansion (CTE). ..

In order to solve the above-mentioned problems, the present inventors have found that a polyimide obtained from a polyamic acid having a specific diamine structure has a low coefficient of thermal expansion (CTE) when a resin film is formed, while having low dielectric properties. We have found that it is possible to obtain a circuit board such as an FPC which can be suppressed and has good transmission characteristics while suppressing the occurrence of warpage, and has completed the present invention.

That is, the polyamic acid of the present invention is a polyamic acid obtained by reacting a diamine component with an acid anhydride component containing a tetracarboxylic acid anhydride.
The diamine component is characterized by containing the diamine compound represented by the following general formula (i) in the range of 5 to 100 mol% with respect to the total diamine component.

In formula (i), R _{1 to} R ₈ independently represent a hydrogen atom or an alkyl group or an alkoxy group having 1 to 20 carbon atoms, but the total number of carbon atoms of R _{1 to} R ₈ is 12 to 40.

The polyamic acid of the present invention may contain the diamine compound represented by the general formula (i) in the range of 5 to 70 mol% with respect to the total diamine component.
The pyromellitic anhydride (PMDA) may be contained in the range of 30 to 100 mol% with respect to the acid anhydride component.

The polyamic acid of the present invention may contain the diamine compound represented by the following general formula (ii) in the diamine component in the range of 30 to 95 mol% with respect to the total diamine component.

Wherein (ii), R ₉ and R ₁₀ each independently represent a hydrogen atom, a halogen atom or an alkyl group which may be substituted with halogen atoms having 1 to 3 carbon atoms, although an alkoxy group or alkenyl group, R ₉ and The total number of carbon atoms of R ₁₀ is 0 to 11, and m and n are independently 1 to 4.

The polyimide of the present invention is obtained by imidizing any of the above polyamic acids.

The resin film of the present invention may contain a polyimide obtained by imidizing any of the above polyamic acids. In this case, the coefficient of thermal expansion of the resin film may be in the range of 10 × 10 ^-6 to 30 × 10 ^-6 (1 / K).

The metal-clad laminate of the present invention is a metal-clad laminate provided with an insulating resin layer and a metal layer, wherein the resin insulating layer has a single layer or a plurality of polyimide layers, and at least the polyimide layer is provided. One layer is a polyimide layer having a coefficient of thermal expansion in the range of 10 × 10 ^-6 to 30 × 10 ^-6 (1 / K), and the polyimide layer is formed by imidizing any of the above polyamic acids. It was done.

The polyamic acid and polyimide of the present invention form a resin film while having low dielectric properties by using a diamine compound of the general formula (i) in which an alkyl group or an alkoxy group having a specific carbon number is introduced into the side chain. Even in this case, the decrease in the glass transition temperature (Tg) can be suppressed, and the increase in the coefficient of thermal expansion (CTE) can also be suppressed low. Therefore, the resin film using the polyamic acid and the polyimide of the present invention can be suitably used, for example, as an insulating resin layer of a metal-clad laminate. Further, by using the polyamic acid and the polyimide of the present invention as the insulating layer material, it is possible to provide a circuit board such as FPC having good transmission characteristics while suppressing the occurrence of warpage.

Hereinafter, embodiments of the present invention will be described.

[Polyamic acid and polyimide]
<Polyamic acid>
The polyamic acid of the present embodiment is a precursor of the polyimide of the present embodiment, and is obtained by reacting a diamine component with an acid anhydride component containing a tetracarboxylic acid anhydride. Here, the diamine component is a diamine compound represented by the general formula (i) (hereinafter, may be referred to as “diamine compound (i)”) within a range of 5 to 100 mol% with respect to the total diamine component. Included in.

In formula (i), R _{1 to} R ₈ independently represent a hydrogen atom or an alkyl group or an alkoxy group having 1 to 20 carbon atoms, but the total number of carbon atoms of R _{1 to} R ₈ is 12 to 40.

In the diamine compound (i), the alkyl group or alkoxy group constituting the substituents R _{1 to} R ₈ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms. It may be an alkoxy group having a straight chain, a branched chain or a cyclic alkyl chain, preferably a straight chain having 8 to 18 carbon atoms, a branched chain or a cyclic alkyl group, a straight chain having 8 to 18 carbon atoms, or a branched group. An alkoxy group having a chain or a cyclic alkyl chain. Further, as the diamine compound (i), it is preferable that each of the two aromatic rings in the general formula (i) has one or more of the above alkyl groups or alkoxy groups as substituents.

Examples of preferred diamine compounds include, for example, 3,3'-di-n-octadecyloxy-4,4'-diaminobiphenyl, 3,3'-di-n-octyloxy-4,4'-diaminobiphenyl. 3,3'-bis (2-ethylhexyloxy) -4,4'-diaminobiphenyl, 3,3'-bis (methylcyclohexyloxy) -4,4'-diaminobiphenyl, 2,2'-di-n- Octyloxy-4,4'-diaminobiphenyl, 2,2'-bis (2-ethylhexyloxy) -4,4'-diaminobiphenyl, 2,2'-bis (methylcyclohexyloxy) -4,4'-diamino Examples thereof include biphenyl, 2,2'-di-n-dodecyloxy-4,4'-diaminobiphenyl and the like. Among these, 2,2'-di-n-octyloxy-4,4'-diaminobiphenyl, 2,2'-bis (2-ethylhexyloxy) -4,4'-diaminobiphenyl, 2,2'- Bis (methylcyclohexyloxy) -4,4'-diaminobiphenyl, 2,2'-di-n-dodecyloxy-4,4'-diaminobiphenyl and the like are preferable.

A feature of the diamine compound (i) is that by introducing a low-polarity alkyl group or alkoxy group into the side chain, the concentration of polar groups as polyimide is reduced and the concentration of imide groups is lowered, resulting in low dielectric properties. can do. Further, since the rigid benzidine skeleton is the main clavicle skeleton, the decrease in Tg can be suppressed and the significant increase in CTE can be suppressed.

In the polyamic acid of the present embodiment, the diamine component contains the diamine compound (i) in the range of 5 to 100 mol% with respect to the total diamine component. In the case of achieving both low dielectric constant and low CTE of the resin film formed by using the polyamic acid of the present embodiment, the diamine compound (i) is preferably in the range of 5 to 70 mol%, more preferably 10 to 60. It is recommended to use within the range of mol%.

As a method for producing the diamine compound (i), for example, the amino group of 3,3'-dihydroxy-4,4'-diaminobiphenyl is protected, a side chain is introduced by a Williamson reaction or a Mitsunobu reaction, and then deprotection is performed. The method can be mentioned.

In order to achieve both low dielectric constant and low CTE in the resin film formed by using the polyamic acid of the present embodiment, a diamine compound represented by the following general formula (ii) is used as another diamine component as a total diamine. It is preferably in the range of 30 to 95 mol%, more preferably in the range of 40 to 90 mol% with respect to the component.

Wherein (ii), R ₉ and R ₁₀ each independently represent a hydrogen atom, a halogen atom or an alkyl group which may be substituted with halogen atoms having 1 to 3 carbon atoms, although an alkoxy group or alkenyl group, R ₉ and The total number of carbon atoms of R ₁₀ is 0 to 11, and m and n are independently 1 to 4.

Specific examples of the diamine compound (ii) include 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) and 2,2'-bis (trifluoromethyl) -4,4'-diamino. Biphenyl (TFMB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2 '-Divinyl-4,4'-diaminobiphenyl (VAB) and the like can be mentioned. Among these, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB) is a diamine component that contributes to lowering the CTE of the resin film formed by using the polyamic acid of the present embodiment. ), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-n-propyl -4,4'-diaminobiphenyl (m-NPB) and the like are particularly preferable.

Examples of diamines other than the diamine compounds (i) and (ii) include 4,4'-diaminodiphenyl ether, 2'-methoxy-4,4'-diaminobenzanilide, and 1,4-bis (4-amino). Phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 3,3'-dihydroxy-4,4'-diaminobiphenyl , 4,4'-diaminobenzanilide, 2,2-bis- [4- (3-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3- (3-)3- Aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-aminophenoxy)] biphenyl, bis [1-( 3-Aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] ether, Bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy)] benzophenone, bis [4- (3-aminophenoxy)] benzophenone, bis [4,4'-(4-) Aminophenoxy)] benzanilide, bis [4,4'-(3-aminophenoxy)] benzanilide, 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3) -Aminophenoxy) phenyl] fluorene, 2,2-bis- [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis- [4- (3-aminophenoxy) phenyl] hexafluoropropane, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 4,4'-diaminodiphenylpropane, 3,3 '-Diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3 , 3'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diamino Diphenyl ether, 3,3-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4''-diamino-p-terphenyl, 3,3''-diamino-p-terphenyl, m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 1,4-bis (4) -Aminophenoxy) 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-tert-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-tert-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylene diamine, p-xylylene diamine , 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine and the like.

Based on the dielectric properties of polyimide, the aromatic tetracarboxylic dianhydride used in the preparation of the polyamic acid of the present embodiment contains 30 mol% or more of pyromellitic dianhydride (PMDA) with respect to the acid anhydride component. More specifically, it is preferably used in the range of 30 to 100 mol%. By using 30 mol% or more of PMDA, it is possible to reduce the CTE of the resin film formed from the polyamic acid of the present embodiment.

Examples of other acid anhydrides include 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4. '-Oxydiphthalic anhydride is preferably exemplified. In addition, as an acid anhydride, 2,2', 3,3'-, 2,3,3', 4'-or 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 2,3 ', 3,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dianhydride, 2,3', 3,4'-diphenyl ether tetracarboxylic acid dianhydride , Bis (2,3-dicarboxyphenyl) ether dianhydride, 3,3'', 4,4''-, 2,3,3'', 4''-or 2,2'',3, 3''-p-terphenyltetracarboxylic dianhydride, 2,2-bis (2,3- or 3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3- or 3.4) -Dicarboxyphenyl) methane dianhydride, bis (2,3- or 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane Dianhydride 1,2,7,8-,1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic acid dianhydride 2,3,6,7-anthracene tetracarboxylic Acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalene tetracarboxylic Acid dianhydride 1,2,5,6-naphthalenetetracarboxylic acid dianhydride 1,4,5,8-naphthalenetetracarboxylic acid dianhydride 4,8-dimethyl-1,2,3,5 , 6,7-Hexahydronaphthalene-1,2,5,6-tetracarboxylic acid 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 dianhydride, 2,3,8,9-,3,4,9,10-4,5,10,11-or 5,6,11,12-perylene-tetracarboxylic hydride, cyclopentane-1,2 , 3,4-Tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride, thiophene-2, Examples thereof include 3,4,5-tetracarboxylic acid dianhydride, 4,4'-bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride and the like.

<Polyimide>
The polyimide of the present embodiment is obtained by imidizing the above polyamic acid, and is generally produced by reacting an acid anhydride with a diamine. Therefore, the present embodiment will be described by explaining the acid anhydride and the diamine. Specific examples of polyimides in the form of are understood.

In the polyimide of the present embodiment, the diamine compound (i) is indispensably used as the diamine component as the diamine component to reduce the imide group concentration, obtain low dielectric properties, and suppress a significant increase in CTE of the resin film. can do.

In the polyimide of the present embodiment, by selecting the types of the acid anhydride and diamine and the molar ratio of each when two or more kinds of acid anhydride or diamine are used, thermal expansion, adhesiveness, and glass The transition temperature (Tg) and the like can be controlled.

The polyimide according to the present invention can be produced by reacting a diamine component containing a diamine compound (i) with an acid anhydride component containing a tetracarboxylic acid anhydride in a solvent to generate a polyamic acid, and then heating and closing the ring. .. For example, it is a precursor of polyimide by dissolving an acid anhydride component and a diamine component in an organic solvent in approximately equimolar amounts, stirring at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours, and carrying out a polymerization reaction. Polyamic acid is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the precursor produced is in the range of 5 to 30% by weight, preferably in the range of 10 to 20% by weight. Examples of the organic solvent used in the polymerization reaction include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N, N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2 -Butanone, dimethyl sulfoxide (DMSO), hexamethylphospholamide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglime, triglime, cresol and the like can be mentioned. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can be used in combination. The amount of such an organic solvent used is not particularly limited, but it should be adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 30% by weight. Is preferable.

The synthesized polyamic acid is usually advantageous to be used as a reaction solvent solution, but can be concentrated, diluted or replaced with another organic solvent if necessary. In addition, polyamic acid is generally excellent in solvent solubility and is therefore used advantageously. The viscosity of the polyamic acid solution is preferably in the range of 500 cP to 100,000 cP. If it is out of this range, defects such as thickness unevenness and streaks are likely to occur in the film during coating work by a coater or the like. The method for imidizing the polyamic acid is not particularly limited, and for example, a heat treatment such as heating in the solvent under a temperature condition in the range of 80 to 400 ° C. for 1 to 24 hours is preferably adopted.

[Resin film]
The resin film of the present embodiment is not particularly limited as long as it is an insulating resin film containing a polyimide layer formed from the polyimide of the present embodiment, and may be a film (sheet) made of an insulating resin. Often, it may be an insulating resin film in a state of being laminated on a base material such as a resin sheet such as a copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film. The thickness of the resin film of the present embodiment is preferably in the range of 3 to 100 μm, more preferably in the range of 3 to 75 μm.

The polyimide of the present embodiment is preferably applied as a base film layer (main layer of an insulating resin layer). Specifically, the coefficient of thermal expansion (CTE) is in the range of 10 × 10 ^-6 to 30 × 10 ^-6 (1 / K), preferably 10 × 10 ^{-6 to} 25 × 10 ^-6 (1 / K). A large effect can be obtained by applying a low thermal expansion polyimide layer in the range of 15 × 10 ^{-6 to} 25 × 10 ^-6 (1 / K) to the base film layer. Among the low thermal expansion polyimides, a polyimide that can be preferably used is a non-thermoplastic polyimide. When the polyimide of the present embodiment is used to form a low thermal expansion base film layer, the thickness is preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 35 μm.

On the other hand, the highly expandable polyimide layer exceeding the coefficient of thermal expansion (CTE) is also preferably applied as an adhesive layer to a base material such as a metal layer or another resin layer. As the polyimide that can be suitably used as such an adhesive polyimide layer, a polyimide having a glass transition temperature (Tg) of, for example, 360 ° C. or lower is preferable, and a polyimide having a glass transition temperature (Tg) in the range of 200 to 320 ° C. is more preferable.

To obtain a highly expandable polyimide layer, for example, pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', as an acid anhydride component of the raw material 4,4'-Benzenephenone tetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, as a diamine component, 2,2'-bis [4- (4- (4- (4- (4-) Aminophenoxy) phenyl] propane, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene are preferably used, and particularly preferably pyromellitic dianhydride and 2,2'-bis [ 4- (4-Aminophenoxy) phenyl] Propane should be the main component of each component of the raw material.

The method for forming the polyimide film as the resin film of the present embodiment is not particularly limited. For example, [1] a polyimide film is produced by applying a polyamic acid solution to a supporting base material, drying the film, and then imidizing the polyimide film. A method (hereinafter referred to as a casting method), [2] a method of applying a polyamic acid solution to a support base material, drying it, peeling the polyamic acid gel film from the support base material, and imidizing the support base material to produce a polyimide film. Can be mentioned. When the polyimide film produced in the present invention is composed of a plurality of polyimide resin layers, as an embodiment of the production method, for example, [3] a support base material is coated with a polyamic acid solution and dried. After repeating the above multiple times, imidization is performed (hereinafter referred to as the sequential coating method). [4] The support substrate is simultaneously coated and dried with a laminated structure of polyamic acid by multi-layer extrusion, and then imidization is performed. Examples thereof include a method (hereinafter referred to as a multilayer extrusion method). The method of applying the polyimide solution (or polyamic acid solution) on the substrate is not particularly limited, and for example, it can be applied with a coater such as a comma, a die, a knife, or a lip. When forming the multilayer polyimide layer, a method of repeatedly applying a polyimide solution (or a polyamic acid solution) to the substrate and drying the substrate is preferable.

The resin film of the present embodiment may include a single layer or a plurality of layers of polyimide layers. In this case, at least one layer (preferably a base film layer) of the polyimide layer may be formed by using the non-thermoplastic polyimide of the present embodiment. For example, assuming that the non-thermoplastic polyimide layer is P1 and the thermoplastic polyimide layer is P2, it is preferable to laminate the resin film in a combination of P2 / P1 when the resin film is two layers, and when the resin film is three layers. Is preferably laminated in the order of P2 / P1 / P2 or P2 / P1 / P1. Here, P1 becomes a base film layer formed by using the non-thermoplastic polyimide of the present embodiment. In addition, P2 may be composed of polyimide other than the polyimide of this embodiment.

The resin film of the present embodiment may contain an inorganic filler in the polyimide layer, if necessary. Specific examples thereof include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride and calcium fluoride. These can be used alone or in admixture of two or more.

The resin film of the present embodiment applied as a low thermal expansion polyimide film can be applied, for example, as a coverlay film material in a coverlay film. An arbitrary adhesive layer can be laminated on the resin film of the present embodiment to form a coverlay film. The thickness of the coverlay film material layer is not particularly limited, but is preferably 5 μm or more and 100 μm or less, for example. The thickness of the adhesive layer is not particularly limited, but is preferably 25 μm or more and 50 μm or less, for example.

The resin film of the present embodiment applied as an adhesive polyimide film can also be used, for example, as a bonding sheet for a multilayer FPC. When used as a bonding sheet, the resin film of the present embodiment may be used as it is as a bonding sheet on an arbitrary base film, or the resin film may be used in a state of being laminated with an arbitrary base film. May be good.

[Metal-clad laminate]
The metal-clad laminate of the present embodiment has an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer. A preferable specific example of the metal-clad laminate is, for example, a copper-clad laminate (CCL).

<Insulation resin layer>
In the metal-clad laminate of the present embodiment, the insulating resin layer has a single layer or a plurality of polyimide layers. In this case, in order to impart excellent high-frequency characteristics to the metal-clad laminate, at least one layer (preferably a base film layer) of the polyimide layer is formed by using the non-thermoplastic polyimide of the present embodiment. Just do it. Further, in order to enhance the adhesiveness between the insulating resin layer and the metal layer, the layer of the insulating resin layer in contact with the metal layer is preferably a thermoplastic polyimide layer. For example, when the insulating resin layer is two layers, if the non-thermoplastic polyimide layer is P1, the thermoplastic polyimide layer is P2, and the metal layer is M1, it is preferable to stack P1 / P2 / M1 in this order. Here, P1 becomes a base film layer formed by using the non-thermoplastic polyimide of the present embodiment. In addition, P2 may be composed of polyimide other than the polyimide of this embodiment.

<Metal layer>
The material of the metal layer in the metal-clad laminate of the present embodiment is not particularly limited, but for example, copper, stainless steel, iron, nickel, berylium, aluminum, zinc, indium, silver, gold, tin, zirconium, and tantalum. , Titanium, lead, magnesium, manganese and alloys thereof. Of these, copper or copper alloys are particularly preferable. The material of the wiring layer in the circuit board of the present embodiment described later is also the same as that of the metal layer.

When a high-frequency signal is supplied to the signal wiring, the current flows only on the surface of the signal wiring, and the effective cross-sectional area where the current flows decreases, the DC resistance increases, and the signal attenuates (skin effect). is there. By lowering the surface roughness of the surface of the metal layer in contact with the insulating resin layer, it is possible to suppress an increase in signal wiring resistance due to this skin effect. However, if the surface roughness is lowered in order to satisfy the required electrical performance standards, the adhesive strength (peeling strength) between the copper foil and the dielectric substrate becomes weak. Therefore, from the viewpoint of satisfying the electrical performance requirements and improving the visibility of the metal-clad laminate while ensuring the adhesiveness with the insulating resin layer, the surface roughness of the surface of the metal layer in contact with the insulating resin layer is determined. The ten-point average roughness Rz is preferably 1.5 μm or less, and the arithmetic average roughness Ra is preferably 0.2 μm or less.

The metal-clad laminate is prepared, for example, by preparing a resin film composed of the polyimide of the present embodiment, sputtering a metal on the resin film to form a seed layer, and then forming a metal layer by plating, for example. You may.

Further, the metal-clad laminate may be prepared by preparing a resin film composed of the polyimide of the present embodiment and laminating a metal foil on the resin film by a method such as thermocompression bonding.

Further, in the metal-clad laminate, a coating liquid containing polyamic acid, which is a precursor of the polyimide of the present embodiment, is cast on a metal foil, dried to form a coating film, and then heat-treated to imidize. It may be prepared by forming a polyimide layer.

[Circuit board]
The circuit board of the present embodiment has an insulating resin layer and a wiring layer formed on the insulating resin layer. In the circuit board of the present embodiment, the insulating resin layer may have a single layer or a plurality of polyimide layers. In this case, in order to impart excellent high frequency characteristics to the circuit board, at least one layer (preferably a base film layer) of the polyimide layer may be formed by using the non-thermoplastic polyimide of the present embodiment. .. Further, in order to enhance the adhesiveness between the insulating resin layer and the wiring layer, it is preferable that the layer in contact with the wiring layer in the insulating resin layer is a thermoplastic polyimide layer formed by using the polyimide of the present embodiment. For example, when the insulating resin layer is two layers, if the non-thermoplastic polyimide layer is P1, the thermoplastic polyimide layer is P2, and the wiring layer is M2, it is preferable to stack P1 / P2 / M2 in this order. Here, P1 becomes a base film layer formed by using the non-thermoplastic polyimide of the present embodiment. In addition, P2 may be composed of polyimide other than the polyimide of this embodiment.

A method for producing a circuit board is not limited except that the polyimide of the present embodiment is used. For example, a subtractive method may be used in which a metal-clad laminate composed of an insulating resin layer containing polyimide and a metal layer of the present embodiment is prepared and the metal layer is etched to form wiring. Further, a semi-additive method may be used in which the seed layer is formed on the polyimide layer of the present embodiment, the resist is patterned, and the metal is pattern-plated to form the wiring.

As described above, by using the polyimide of the present embodiment, it is possible to form a metal-clad laminate with a small transmission loss.

Examples will be shown below, and the features of the present invention will be described in more detail. However, the scope of the present invention is not limited to the examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of glass transition temperature (Tg)]
The glass transition temperature is a heating rate of a polyimide film having a size of 5 mm × 20 mm from 30 ° C. to 400 ° C. using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F). The measurement was performed at 4 ° C./min and a frequency of 11 Hz, and the temperature was determined from the maximum temperature of tan δ based on the main dispersion.

[Measurement of coefficient of thermal expansion (CTE)]
The coefficient of thermal expansion is 30 ° C to 265 ° C at a constant temperature rise rate while applying a load of 5.0 g to a polyimide film with a size of 3 mm × 20 mm using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). The temperature was raised to 100 ° C., held at that temperature for 10 minutes, and then cooled at a rate of 5 ° C./min to obtain an average coefficient of thermal expansion (linear thermal expansion coefficient) from 250 ° C. to 100 ° C.

[Measurement of permittivity]
For the permittivity and the permittivity of the resin sheet (resin sheet after curing) at a frequency of 3 GHz, a cavity resonator perturbation method permittivity evaluator (manufactured by Agilent, trade name; vector network analyzer E8633B) is used. It was measured. The resin sheet used for the measurement was left to stand for 24 hours under the conditions of temperature: 24-26 ° C. and humidity: 45-55%. The dielectric constant was 3.3 or less as a reference, and when the dielectric constant was 3.2 or less, it was evaluated as excellent.

The abbreviations used in Examples and Comparative Examples indicate the following compounds.
o-HAB: 3,3'-dihydroxy-4,4'-diaminobiphenyl m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TFMB: 2,2'-bis (trifluoromethyl)- 4,4'-Diaminobiphenyl PDA: p-phenylenediamine PMDA: pyromellitic acid dianhydride BPDA: 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride NMP: N-methyl-2-pyrrolidone DMF : N, N-dimethylformamide DMAc: N, N-dimethylacetamide THF: tetrahydrofurandiamine A: 3,3'-di-n-octadecyloxy-4,4'-diaminobiphenyldiamine B: 3,3'-di- n-octyloxy-4,4'-diaminobiphenyldiamine C: 3,3'-bis (2-ethylhexyloxy) -4,4'-diaminobiphenyldiamine D: 3,3'-bis (methylcyclohexyloxy)- 4,4'-Diaminobiphenyldiamine E: 2,2'-di-n-octyloxy-4,4'-diaminobiphenyl

(Synthesis of diamine A)
Under a nitrogen atmosphere, 17.30 g of o-HAB (80 mmol) was added to a four-necked flask containing a stirrer, dissolved in 200 ml of NMP, 23.94 g of phthalic anhydride (162 mmol) was added, and the mixture was stirred at 170 ° C. for 6 hours. Was done. Then, it cooled to room temperature, and the solid part was recovered by filtration.

The obtained solid portion is added to a three-necked flask containing a stirrer, dissolved in 400 ml of DMF, 33.17 g of potassium carbonate (240 mmol) is added and stirred, and 64.78 g of 1-bromooctadecane (192 mmol) is added. The mixture was stirred at 80 ° C. for 5 hours. Then, it was cooled to room temperature, and the solid part was recovered by filtration. The obtained solid portion was washed with water and dried under reduced pressure to obtain 44.06 g of Compound A (47 mmol).

37.66 g of Compound A (40 mmol) and 400 ml of DMAc were added to a three-necked flask containing a stirrer and stirred, 18.02 g of hydrazine monohydrate (360 mmol) was added, and the mixture was stirred at 40 ° C. for 4 hours. The mixture was cooled to room temperature and the solid part was recovered by filtration. The obtained solid portion was dissolved in 800 ml of THF, 800 ml of acetone was added, and the mixture was sufficiently stirred, and then allowed to stand in a freezer overnight. The precipitated solid portion was collected by filtration and dried under reduced pressure to obtain 23.66 g of diamine A (33 mmol).

(Synthesis of diamine B)
Under a nitrogen atmosphere, 17.30 g of o-HAB (80 mmol) was added to a four-necked flask containing a stirrer, dissolved in 200 ml of NMP, 23.94 g of phthalic anhydride (162 mmol) was added, and the mixture was stirred at 170 ° C. for 6 hours. Was done. Then, it cooled to room temperature, and the solid part was recovered by filtration.

The obtained solid portion is added to a three-necked flask containing a stirrer, dissolved in 400 ml of DMF, 33.17 g of potassium carbonate (240 mmol) is added and stirred, and 37.08 g of 1-bromooctane (192 mmol) is added. The mixture was stirred at 80 ° C. for 5 hours. Then, the mixture was cooled to room temperature and filtered to collect the filtrate. After concentrating the filtrate, purification by column chromatography was performed to obtain 32.0 g of Compound B (45.6 mmol).

28.04 g of Compound B (40 mmol) and 400 ml of DMAc were added to a three-necked flask containing a stirrer and stirred, 18.02 g of hydrazine monohydrate (360 mmol) was added, and the mixture was stirred at 40 ° C. for 4 hours. The mixture was cooled to room temperature and the solid part was recovered by filtration. The obtained solid portion was dissolved in 800 ml of THF, 800 ml of acetone was added, and the mixture was sufficiently stirred, and then allowed to stand in a freezer overnight. The precipitated solid portion was collected by filtration and dried under reduced pressure to obtain 13.40 g of diamine B (30.4 mmol).

(Synthesis of diamine C)
Compound C and diamine C were obtained in the same manner as in the synthesis of diamine B except that 1-bromo-2-ethylhexane was used instead of 1-bromooctane.

(Synthesis of diamine D)
Compound D and diamine D were obtained in the same manner as in the synthesis of diamine B, except that (bromomethyl) cyclohexane was used instead of 1-bromooctane.

(Synthesis of diamine E)
Compound E and diamine E were obtained in the same manner as in the synthesis of diamine B, except that 2,2'-dihydroxy-4,4'-diaminobiphenyl was used instead of o-HAB.

[Example 1]
(1) Preparation of polyamic acid Under a nitrogen atmosphere, 2.2682 g of diamine A (3.15 mmol), 6.0090 g of m-TB (28.31 mmol) and 85 g of DMAc / xylene mixed solvent were added to a separable flask. And stirred at room temperature. Next, after adding 6.7228 g of PMDA (30.82 mmol), the polymerization reaction was carried out by continuing stirring at room temperature for 4 hours to obtain a polyamic acid solution a.

(2) Preparation of Polyimide Film After applying the polyamic acid solution a uniformly to one side (surface roughness Rz; 1.06 μm) of an electrolytic copper foil having a thickness of 12 μm so that the cured thickness becomes about 25 μm. The solvent was removed by heating and drying at 120 ° C. Further, heat treatment was carried out stepwise from 120 ° C. to 320 ° C. to complete imidization. A copper foil was etched and removed from the obtained metal-clad laminate with an aqueous ferric chloride solution to obtain a polyimide film A. The Tg of the obtained polyimide film A is 400 ° C. or higher, and the CTE and the dielectric constant are shown in Table 1.

[Examples 2 to 13]
Polyamide acid solutions b to m and polyimide films B to M were prepared in the same manner as in Example 1 except that the raw material compositions shown in Table 1 were used. The Tg of the obtained polyimide films B to M is 400 ° C. or higher, and the CTE and the dielectric constant are shown in Table 1.

From the results of Examples 1 to 8, if the side chain of the diamine compound (i) has a large number of carbon atoms, the dielectric constant can be reduced with a small amount, and even if the diamine compound (i) has a small number of carbon atoms, the dielectric constant can be reduced by adjusting the composition ratio. Can be converted.

Further, from the results of Example 12, it is possible to obtain an extremely low dielectric constant by using the diamine compound (i) having a large number of carbon atoms in the side chain, and the Tg does not decrease even at such a low dielectric constant. It is considered that this is because the main chain skeleton is rigid and does not contain a bent structure in the main chain.

[Examples 14 and 15]
Polyamide acid solutions n and o and polyimide films N and O were prepared in the same manner as in Example 1 except that the raw material compositions shown in Table 2 were used. Table 2 shows the CTE and dielectric constant of the obtained polyimide films N and O.

From Example 14 and Example 9, it is possible to adjust CTE while maintaining a low dielectric constant by changing the copolymerization ratio with an acid anhydride (here, BPDA) other than PMDA.

From Example 15, if the diamine compound (i) is contained in an appropriate ratio, it is possible to achieve both CTE and low dielectric constant other than the diamine compound (ii).

[Comparative Example 1]
A polyamic acid solution p and a polyimide film P were prepared in the same manner as in Example 1 except that the raw material compositions shown in Table 3 were used. Table 3 shows the CTE and the dielectric constant of the obtained polyimide film P.

From Comparative Example 1 (and Example 15), it can be seen that with a diamine compound having a small number of alkyl groups in the side chain, it is possible to obtain a low CTE, but at the same time it is difficult to reduce the dielectric constant.

Although the embodiments of the present invention have been described in detail for the purpose of exemplification, the present invention is not limited to the above embodiments and can be modified in various ways.

Claims (7)

A polyamic acid used for forming the polyimide layer in a circuit board including an insulating resin layer having a single-layer or a plurality of polyimide layers and a wiring layer.
The polyamic acid is obtained by reacting a diamine component with an acid anhydride component containing a tetracarboxylic dianhydride .
A polyamic acid in which the diamine component contains a diamine compound represented by the following general formula (i) in the range of 5 to 100 mol% with respect to the total diamine component.

[In the formula, R _{1 to} R ₈ each independently represent a hydrogen atom or an alkyl group or an alkoxy group having 1 to 20 carbon atoms, but the total number of carbon atoms of R _{1 to} R ₈ is 12 to 40. ] The diamine compound represented by the general formula (i) is contained in the range of 5 to 70 mol% with respect to the total diamine component.
The polyamic acid according to claim 1, wherein the pyromellitic anhydride (PMDA) is contained in the range of 30 to 100 mol% with respect to the acid anhydride component. The polyamic acid according to claim 2, wherein the diamine component contains a diamine compound represented by the following general formula (ii) in the range of 30 to 95 mol% with respect to the total diamine component.

[In the formula, R ₉ and R ₁₀ indicate an alkyl group, an alkoxy group or an alkenyl group which may be independently substituted with a hydrogen atom, a halogen atom or a halogen atom having 1 to 3 carbon atoms, respectively, but R ₉ and R ₁₀ The total number of carbon atoms in is 0 to 11, and m and n are independently 1 to 4. ] The polyimide used for forming the polyimide layer in a circuit board including an insulating resin layer having a single layer or a plurality of polyimide layers and a wiring layer, according to any one of claims 1 to 3. Polyimide obtained by imidizing the polyamic acid of. A resin film used for forming the polyimide layer in a circuit substrate including an insulating resin layer having a single-layer or a plurality of polyimide layers and a wiring layer, according to any one of claims 1 to 3. A resin film containing a polyimide obtained by imidizing the above-mentioned polyamic acid. A resin film used for forming the polyimide layer in a circuit substrate including an insulating resin layer having a single-layer or a plurality of polyimide layers and a wiring layer, in which the polyamic acid according to claim 2 is imidized. The resin film obtained in the above, wherein the coefficient of thermal expansion is in the range of 10 × 10 ^-6 to 30 × 10 ^-6 (1 / K). A metal-clad laminate having an insulating resin layer and a metal layer.
The resin insulating layer has a single layer or a plurality of polyimide layers.
At least one of the polyimide layers is a polyimide layer having a coefficient of thermal expansion in the range of 10 × 10 ^-6 to 30 × 10 ^-6 (1 / K), and the polyimide layer contains a diamine component and a tetracarboxylic acid. It is formed by imidizing a polyamic acid obtained by reacting an acid anhydride component containing an acid anhydride with an acid anhydride component.
The diamine component contains a diamine compound represented by the following general formula (i) in the range of 5 to 70 mol% with respect to the total diamine component.
A metal-clad laminate characterized by containing pyromellitic anhydride (PMDA) in the range of 30 to 100 mol% with respect to the acid anhydride component.

[In the formula, R _{1 to} R ₈ each independently represent a hydrogen atom or an alkyl group or an alkoxy group having 1 to 20 carbon atoms, but the total number of carbon atoms of R _{1 to} R ₈ is 12 to 40. ]