JP2016188298A - Polyimide, resin film, metal-clad laminate, and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide excellent in dielectric characteristics and dimensional stability after heat treatment, a resin film and a metal-clad laminate.SOLUTION: There is polyimide which contains i) 70-100 mol% of pyromellitic dianhydride in whole tetracarboxylic acid dianhydride; ii) 4-8 mol% of dimer acid type diamine obtained by substituting a primary aminomethyl group or an amino group for two terminal carboxylic acid groups of dimer acid, and aromatic diamine in whole diamine; iii) 76-92 mol% of 4,4'-diaminobiphenyl; and iv) 4-16 mol% of diamine represented by formula (2).SELECTED DRAWING: None

Description

  The present invention relates to polyimide, a resin film using the same, a metal-clad laminate, and a circuit board.

  In recent years, with the progress of downsizing, weight reduction, and space saving of electronic devices, flexible printed wiring boards (FPCs) that are thin, light, flexible, and have excellent durability even after repeated bending are used. The demand for Circuits) is increasing. FPC can be mounted three-dimensionally and densely in a limited space. For example, it can be used for wiring of movable parts of electronic devices such as HDDs, DVDs, mobile phones, and parts such as cables and connectors. It is expanding.

  In addition to the above-described higher density, higher performance of equipment has been advanced, so that it is necessary to cope with higher frequency transmission signals. When transmitting a high-frequency signal, if there is a point where the impedance changes in the signal transmission path, the electromagnetic wave is reflected at that point, causing problems such as loss of an electric signal and disturbance of the signal waveform. Therefore, impedance matching of the FPC becomes an important characteristic. In order to cope with higher frequencies, FPC using a liquid crystal polymer characterized by a low dielectric constant and a low dielectric loss tangent as a dielectric layer is used. However, although the liquid crystal polymer is excellent in dielectric properties, there is room for improvement in heat resistance and adhesion to metal foil.

  In order to improve heat resistance and adhesiveness, a metal-clad laminate using 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 polymer as a monomer, and an aliphatic (chain) tetracarboxylic dianhydride is used. Since the heat resistance of the polyimide obtained in this way is extremely low, it cannot be used for processing such as soldering, and there is a problem in practical use. It is said that polyimide with improved heat resistance can be obtained. However, although such a polyimide film has a dielectric constant at 10 GHz of 3.2 or less, the dielectric loss tangent exceeds 0.01, and the dielectric properties have not been sufficient.

  The present inventors previously proposed a polyimide that contains a predetermined amount of dimer acid type diamine as a raw material diamine component in order to provide a circuit board excellent in impedance matching in a high frequency region by suppressing dielectric loss tangent. (Patent Document 2).

JP 2004-358916 A International Publication WO2014 / 208644

  A polyimide in which a certain amount or more of dimer acid type diamine is blended as a raw material diamine component tends to have a large dimensional change rate due to heat treatment. On the other hand, if the blending amount of the dimer acid diamine is too small, the low dielectric loss tangent effect tends to be small and the influence on the dielectric loss tangent by the heat treatment conditions tends to be large.

  An object of the present invention is to provide a polyimide, a resin film, and a metal-clad laminate that can cope with a high frequency associated with downsizing and high performance of an electronic device and that has excellent dimensional stability after heat treatment.

  In order to solve the above-mentioned problems, the present inventors suppress the blending amount of the dimer acid type diamine by using the dimer acid type diamine in combination with a specific tetracarboxylic dianhydride component and a specific diamine compound. As a result, the inventors have found that a polyimide having a low dielectric loss tangent can be obtained stably with little dependence on heat treatment conditions while improving dimensional stability by heat treatment, and the present invention has been completed.

That is, the polyimide of the present invention is obtained by reacting a tetracarboxylic dianhydride component and a diamine component, and the following conditions (i) to (iv);
i) containing pyromellitic dianhydride in the range of 70 to 100 mol% in all tetracarboxylic dianhydrides;
ii) The dimer acid type diamine in which the two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups in the total diamine within a range of 4 to 8 mol%;
iii) containing diamine A represented by the following formula (1) in the range of 76 to 92 mol% in all diamines;
iv) In all diamines, the diamine B represented by the following formula (2) is contained within a range of 4 to 16 mol%;
It is characterized by satisfying.

［Ｒは炭素数３以下のアルキル基、−ＣＦ_３、又は、−ＣＨ＝ＣＨ_２を意味する］

[R represents an alkyl group having 3 or less carbon atoms, —CF ₃ , or —CH═CH ₂ ]

［式中、Ｘは以下の構造を意味する］

[Wherein X means the following structure]

  The polyimide of the present invention may have an imide group concentration of 31 to 33% by weight.

The resin film of the present invention is a resin film having a single layer or multiple polyimide layers,
At least one of the polyimide layers is made of any of the above polyimides.

  The metal-clad laminate of the present invention is a metal-clad laminate comprising an insulating resin layer and a metal layer, and the insulating resin layer is made of the resin film.

  The circuit board of the present invention is obtained by processing the metal layer of the metal-clad laminate into a wiring.

  Since the polyimide of the present invention is used as a raw material in combination with a dimer acid type diamine and a specific tetracarboxylic dianhydride component and a specific diamine compound, it has excellent dimensional stability by heat treatment and dependency on heat treatment conditions. And stable and has a low dielectric loss tangent. Therefore, the polyimide of the present invention can be suitably used as an electronic material that requires high-speed signal transmission. Moreover, by forming a resin base material using the polyimide of the present invention, it can be widely applied to a resin film or a metal-clad laminate depending on the purpose.

  Embodiments of the present invention will be described below.

[Polyimide]
The polyimide according to an embodiment of the present invention is obtained by reacting a tetracarboxylic dianhydride component and a diamine component, and the following (i) to (iv);
i) containing pyromellitic dianhydride in the range of 70 to 100 mol% in all tetracarboxylic dianhydrides;
ii) The dimer acid type diamine in which the two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups in the total diamine within a range of 4 to 8 mol%;
iii) In all diamines, the diamine A represented by the following formula (1) (hereinafter sometimes referred to as “diamine A”) is contained within a range of 76 to 92 mol%;
iv) All diamines contain diamine B represented by the following formula (2) (hereinafter sometimes referred to as “diamine B”) within a range of 4 to 16 mol%;
It is comprised with the polyimide which satisfy | fills these conditions.

［Ｒは炭素数３以下のアルキル基、−ＣＦ_３、又は、−ＣＨ＝ＣＨ_２を意味する］

[R represents an alkyl group having 3 or less carbon atoms, —CF ₃ , or —CH═CH ₂ ]

［式中、Ｘは以下の構造を意味する］

[Wherein X means the following structure]

  Since polyimide is generally produced by reacting a tetracarboxylic dianhydride component and a diamine, a specific example of the polyimide of this embodiment can be understood by explaining the tetracarboxylic dianhydride component and the diamine. Is done. Hereinafter, a preferable polyimide will be described using a tetracarboxylic dianhydride component and a diamine.

(Pyromellitic dianhydride)
The polyimide of this Embodiment contains pyromellitic dianhydride in the range of 70-100 mol% in the total tetracarboxylic dianhydride, Preferably it exists in the range of 80-100 mol%. If the amount of pyromellitic dianhydride in all tetracarboxylic dianhydrides is less than 70 mol%, the coefficient of thermal expansion (CTE) increases and the dimensional stability decreases. Therefore, it is preferable to use 70 mol% or more of pyromellitic dianhydride with respect to all tetracarboxylic dianhydrides, and more preferably 80%.

  The polyimide of this embodiment can use a tetracarboxylic dianhydride component other than pyromellitic dianhydride. Examples of tetracarboxylic dianhydride components other than pyromellitic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetra Preferred examples include carboxylic dianhydride and 4,4′-oxydiphthalic anhydride. Moreover, 2,2 ', 3,3'-, 2,3,3', 4'- or 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,3 ', 3,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3 ', 3,4'-diphenyl ether tetracarboxylic 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-di Carboxyphenyl) methane dianhydride, bis (2,3- or 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane dianhydride Products such as 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic acid Dianhydride 2,2-bis (3,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7- Hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3, 6,7- (or 1,4,5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8 , 9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4- Tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5 -Tetracarboxylic acid Anhydride, 4,4'-bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride and the like.

(Dimer acid type diamine)
The polyimide of this Embodiment contains dimer acid type diamine in the range of 4-8 mol%, Preferably it is in the range of 5-7 mol%. The dimer acid type diamine is a diamine obtained by substituting the primary aminomethyl group (—CH ₂ —NH ₂ ) or the amino group (—NH ₂ ) of the two terminal carboxylic acid groups (—COOH) of the dimer acid. Means.

  Dimer acid is a known dibasic acid obtained by an intermolecular polymerization reaction of an unsaturated fatty acid, and its industrial production process is almost standardized in the industry, and an unsaturated fatty acid having 11 to 22 carbon atoms is converted into a clay catalyst. It is obtained by dimerization with the above. The dimer acid obtained industrially is mainly composed of a dibasic acid having 36 carbon atoms obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid or linoleic acid, depending on the degree of purification. , Containing any amount of monomeric acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. In the first embodiment, it is preferable to use dimer acid whose dimer acid content is increased to 90% by weight or more by molecular distillation. In addition, although a double bond remains after the dimerization reaction, in the first embodiment, the dimer acid further includes a hydrogenation reaction that lowers the degree of unsaturation.

  As a feature of the dimer acid diamine, a characteristic derived from the skeleton of the dimer acid can be provided. That is, since the dimer acid type diamine is a macromolecular aliphatic having a molecular weight of about 560 to 620, the molecular molar volume can be increased and the polar groups of the polyimide can be relatively reduced. Such a feature of the dimer acid type diamine is considered to contribute to improving the dielectric properties while suppressing a decrease in the heat resistance of the polyimide. In addition, since it has two freely moving hydrophobic chains having 7 to 9 carbon atoms and two chain-like aliphatic amino groups having a length close to 18 carbon atoms, not only gives flexibility to the polyimide, Since polyimide can be made into a non-target chemical structure or a non-planar chemical structure, it is thought that the dielectric constant of polyimide can be reduced.

  The charging amount of the dimer acid type diamine is within the range of 4 to 8 mol%, preferably within the range of 5 to 7 mol%, based on the total diamine component. If the dimer acid type diamine is less than 4 mol%, the dielectric properties of the polyimide will be reduced, and the influence of the heat treatment conditions on the dielectric loss tangent will tend to increase. If it exceeds 8 mol%, the dimensional change rate due to the heat treatment Tends to increase and heat resistance deteriorates.

  The dimer acid type diamine is commercially available. For example, PRIAMINE 1073 (trade name) manufactured by Croda Japan, PRIAMINE 1074 (trade name), Versamine 551 (trade name), Versamine 552 (product) manufactured by Cognis Japan. Name).

(Diamine A)
Diamine A is an aromatic diamine, and contributes to the reduction of CTE and the improvement of dielectric properties by improving the orientation and suppressing the moisture absorption rate. From such a viewpoint, the diamine A is used in the range of 76 to 92 mol%, preferably in the range of 82 to 92 mol%, with respect to the total diamine component of the raw material. When the amount of diamine A charged relative to the total diamine component of the raw material is less than 76 mol%, the molecular orientation is lowered and it is difficult to reduce CTE. Moreover, since the compounding ratio of dimer acid type diamine and diamine B will become comparatively low when the preparation amount of diamine A with respect to all the diamine components of a raw material exceeds 92 mol%, the effect which improves the dielectric property of the polyimide obtained. Is not enough.

  Specific examples of diamine A include 2,3′-dimethyl-4,4′-diaminodiphenyl, 3,3 ′, 5-trimethyl-4,4′-diaminodiphenyl, 2,2 ′, 5,5′- Tetramethyl-4,4'-diaminodiphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenyl, 2,3', 5,5'-tetramethyl-4,4'- Diaminodiphenyl, 2,2 ', 3,5-tetramethyl-4,4'-diaminodiphenyl, 2,2', 3,3 ', 5,5'-hexamethyl-4,4'-diaminodiphenyl, 2, 2 ', 3,3', 5,5 ', 6,6'-octamethyl-4,4'-diaminodiphenyl, 2,5-dimethylmethyl-4,4'-diaminodiphenyl, 2,3,5,6 -Tetramethyl-4,4'-diaminodiphenyl, 2,2'-diethyl-4,4'-diaminodiphenyl, 2,2'-propyl-4,4'-diaminodiphenyl, 2,2'-bis (1 -Methylethyl) -4,4'-diaminodiphenyl, 5,5'dimethyl-2,2'-bis (1-methylethyl) -4,4'-diaminodiphenyl, 2,2'-dioctyl-4,4 '- Mino diphenyl, 2,2'-bis mention may be made of (phenylmethyl) -4,4'-diaminodiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl.

  The diamine A is preferably one in which R is an alkyl group having 1 to 3 carbon atoms, 4,4′-diamino-2,2′-dimethyldiphenyl, 4,4′-diamino-3,3′-dimethyldiphenyl. Is more preferable.

(Diamine B)
Diamine B is an aromatic diamine. When combined with dimer acid diamine, diamine B can contribute to reduction of dielectric loss tangent even if the blending amount of dimer acid diamine is suppressed, and indirectly stabilizes the dimension before and after heat treatment of polyimide. Also contributes to improvement of sex. From such a viewpoint, the polyimide of the present embodiment contains diamine B within the range of 4 to 16 mol%, preferably within the range of 6 to 12 mol%, based on the total diamine. If the amount of diamine B is less than 4 mol% in all diamines, it is difficult to obtain a low dielectric loss tangent effect, and if it exceeds 16 mol%, CTE increases and dimensional stability decreases.

  As diamine B, 1,3-bis (4-aminophenoxy) benzene (TPE-R), 1,3-bis (3-aminophenoxy) benzene (APB), 1,4-bis (4-aminophenoxy) Examples include benzene (TPE-Q), 2,2-bis (4-aminophenoxyphenyl) propane (BAPP), and the like.

  A diamine other than the above can also be used for the polyimide of the present embodiment. Examples of diamines other than those described above include diamines other than the diamine A and diamine B diamines such as 4,4′-diaminodiphenyl ether, 2′-methoxy-4,4′-diaminobenzanilide, and 2,2′-dimethyl- 4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 2,2-bis- [4- (3-aminophenoxy) phenyl] propane Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-amino Phenoxy) biphenyl, bis [1- (4-aminophenoxy)] biphenyl, bis [1- (3-aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) phenyl] methane, bis [4- (3 -Aminopheno Si) 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'-diaminodiphenyl Propane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'- Diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl ether, 3,3-diaminodiphenyl ether, 3,4 ′ -Diaminodiphenyl ether, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4 ''-diamino-p-terphenyl, 3,3 ''-diamino-p-terphenyl, m- Phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 4,4 '-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4'-[1,3-phenylenebis (1 -Mechi Ethylidene)] bisaniline, bis (p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2- Methyl-4-aminopentyl) benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino- t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diamino Examples include pyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine and the like.

Based on the dielectric properties of polyimide and the dimensional stability before and after heat treatment, the combination of tetracarboxylic acid anhydride and diamine preferably used for the preparation of the polyimide precursor of the present embodiment includes, for example, tetracarboxylic acid anhydride As pyromellitic dianhydride (PMDA);
2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB) as diamine A; 1,3-bis (4-aminophenoxy) benzene (TPE-R) as diamine B at the above blending ratio Can be listed.

  In the polyimide of the present embodiment, by selecting the types of the above acid anhydride and diamine, and the molar ratios when using two or more acid anhydrides or diamines, thermal expansion, adhesion, glass The transition temperature and the like can be controlled.

  The polyimide of the present embodiment can be produced by reacting the tetracarboxylic acid anhydride, dimer acid type diamine, diamine A, and diamine B in a solvent to form a precursor resin, followed by heating and ring closure. For example, it is a polyimide precursor by dissolving an acid anhydride component and a diamine component in an approximately equimolar amount in an organic solvent and stirring and polymerizing at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours. A polyamic acid is obtained. In the reaction, the reaction components are dissolved so that the precursor to be produced is in the range of 5 to 30% by weight, preferably in the range of 10 to 20% by weight in the organic solvent. Examples of the organic solvent used for the polymerization reaction include N, N-dimethylformamide, N, N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, and dioxane. , Tetrahydrofuran, diglyme, triglyme and the like. Two or more of these solvents can be used in combination, and further, aromatic hydrocarbons such as xylene and toluene can be used in combination. The amount of such organic solvent used is not particularly limited, but the amount used is such that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction is about 5 to 30% by weight. It is preferable to adjust and use.

  The synthesized precursor is usually advantageously used as a reaction solvent solution, but can be concentrated, diluted, or replaced with another organic solvent if necessary. Moreover, since a precursor is generally excellent in solvent solubility, it is advantageously used. The method for imidizing the precursor is not particularly limited, and for example, heat treatment such as heating in the solvent at a temperature within the range of 80 to 400 ° C. for 1 to 24 hours is suitably employed.

The polyimide of this embodiment preferably has an imide group concentration in the range of 31% to 33%. Here, the “imide group concentration” means a value obtained by dividing the molecular weight of the imide group (— (CO) ₂ —N—) in the polyimide by the molecular weight of the entire structure of the polyimide. If the imide group concentration is less than 31%, the dimensional stability is reduced due to a decrease in heat resistance and an increase in CTE, and if it exceeds 33%, the dielectric properties are also deteriorated due to an increase in polar groups. In the polyimide of the present embodiment, the dimer acid type diamine improves the dielectric characteristics, and by selective combination of pyromellitic dianhydride as tetracarboxylic dianhydride, diamine A and diamine B, By controlling the orientation of the molecules in the polyimide, an increase in CTE accompanying a decrease in imide group concentration is suppressed, and both low dielectric properties and high dimensional stability are achieved.

[Resin film]
The resin film of this embodiment is not particularly limited as long as it is an insulating resin film including a polyimide layer formed from the polyimide of the above embodiment, and even a film (sheet) made of an insulating resin. Alternatively, it may be a film of an insulating resin laminated on a substrate such as a resin sheet such as a copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film. Moreover, the thickness of the resin film of 1st Embodiment becomes like this. Preferably it exists in the range of 3-100 micrometers, More preferably, it exists in the range of 3-75 micrometers.

  The resin film of the present embodiment preferably has a dielectric constant at 3 GHz of 3.3 or less in order to ensure impedance matching when used for a circuit board such as an FPC. If the dielectric constant of the resin film at 3 GHz exceeds 3.3, when used for a circuit board such as an FPC, the impedance tends to change on the transmission path of the high-frequency signal, reflection of electromagnetic waves occurs, Inconveniences such as loss and signal waveform disturbance are likely to occur.

  In addition, the resin film of the present embodiment preferably has a dielectric loss tangent at 3 GHz of 0.006 or less in order to ensure impedance matching when used for a circuit board such as an FPC. When the dielectric tangent at 3 GHz of the resin film exceeds 0.006, when used for a circuit board such as an FPC, the impedance tends to change on the transmission path of the high-frequency signal, and reflection of electromagnetic waves occurs. Inconveniences such as loss and signal waveform disturbance are likely to occur.

Among the polyimide layers formed from the polyimide of the present embodiment, the low adhesion and low thermal expansion polyimide layer is suitable for application as a base film layer (main layer of an insulating resin layer). . Specifically, the thermal linear expansion coefficient is in the range of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), preferably in the range of 1 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K). More preferably, when a low thermal expansion polyimide layer in the range of 15 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K) is applied to the base film layer, a great effect can be obtained. On the other hand, a polyimide layer exceeding the thermal linear expansion coefficient is also preferably applied as an adhesive layer with a base material such as a metal layer or another resin layer. As a polyimide that can be suitably used as such an adhesive polyimide layer, a glass transition temperature of, for example, 350 ° C. or lower is preferable, and a glass transition temperature in the range of 200 to 320 ° C. is more preferable.

  The method for forming the polyimide film as the resin film of the present embodiment is not particularly limited. For example, after applying a polyimide solution (or polyamic acid solution) on an arbitrary substrate, heat treatment (drying and curing) is performed. An example is a method of forming a polyimide film (or polyamic acid layer) on a substrate and then peeling it to form a polyimide film. The method for applying the polyimide solution (or polyamic acid solution) on the substrate is not particularly limited, and for example, it can be applied by a coater such as a comma, die, knife, lip or the like. In forming a multi-layer polyimide layer, a method of repeatedly applying and drying a polyimide solution (or polyamic acid solution) on a substrate is preferable.

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

  The resin film of this Embodiment may contain an inorganic filler in a polyimide layer as needed. Specific examples include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, and calcium fluoride. These may be used alone or in combination of two or more.

  What applied the resin film of this Embodiment as a low-thermal-expansion polyimide film can be applied, for example as a film material for coverlays in a coverlay film. A cover lay film can be formed by laminating an arbitrary adhesive layer on the resin film of the present embodiment. 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.

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

[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. Preferable specific examples of the metal-clad laminate include a copper-clad laminate (CCL).

<Insulating resin layer>
In the metal-clad laminate of this 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 of the polyimide layers (preferably the base film layer) is formed using the non-thermoplastic polyimide of the present embodiment. It is preferable. For example, when two insulating resin layers are used, P1 is a non-thermoplastic polyimide layer, P2 is a thermoplastic polyimide layer, and M1 is a metal layer. Here, P1 is a base film layer formed using the non-thermoplastic polyimide of the present embodiment. P2 may be made of a polyimide other than the polyimide of the present embodiment.

  In the metal-clad laminate of the present embodiment, the insulating resin layer preferably has a dielectric constant at 3 GHz of 3.3 or less in order to ensure impedance matching when used for a circuit board such as an FPC. When the dielectric constant of the insulating resin layer at 3 GHz exceeds 3.3, when used on a circuit board such as an FPC, the impedance is likely to change on the transmission path of the high-frequency signal, and reflection of electromagnetic waves occurs. Inconvenience such as loss of signal and disturbance of signal waveform is likely to occur.

  In addition, in the metal-clad laminate of this embodiment, the insulating resin layer may have a dielectric loss tangent at 3 GHz of 0.006 or less in order to ensure impedance matching when used for a circuit board such as an FPC. preferable. If the dielectric tangent at 3 GHz of the insulating resin layer exceeds 0.006, when used for a circuit board such as an FPC, the impedance easily changes on the transmission path of the high-frequency signal, and electromagnetic waves are reflected, resulting in an electrical signal. Inconvenience such as loss of signal and disturbance of signal waveform is likely to occur.

<Metal layer>
The material of the metal layer in the metal-clad laminate of the first embodiment is not particularly limited. For example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium Tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or a copper alloy is particularly preferable. The material of the wiring layer in the circuit board of the first embodiment to be described later is the same as that of the metal layer.

  When a high-frequency signal is supplied to the signal wiring, current flows only on the surface of the signal wiring, the effective cross-sectional area through which the current flows decreases, the DC resistance increases, and the signal attenuates (skin effect) is there. By reducing the surface roughness of the surface of the metal layer in contact with the insulating resin layer, an increase in the resistance of the signal wiring due to the skin effect can be suppressed. However, if the surface roughness is lowered to satisfy the electrical performance requirement standard, 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 adhesion with the insulating resin layer, the surface roughness of the surface of the metal layer in contact with the insulating resin layer is 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 including the polyimide of the above-described embodiment, forming a seed layer by sputtering a metal on the resin film, and then forming the metal layer by, for example, plating. May be.

  The metal-clad laminate may be prepared by preparing a resin film including the polyimide of the above embodiment and laminating a metal foil on the resin film by a method such as thermocompression bonding.

  Further, the metal-clad laminate is cast on a metal foil with a coating solution containing the polyamic acid that is a precursor of the polyimide of the above embodiment, dried to form a coating film, and then heat treated to imidize. Alternatively, it may be prepared by forming a polyimide layer.

[Circuit board]
The circuit board of the present embodiment includes an insulating resin layer and a wiring layer formed on the insulating resin layer. In the circuit board of this embodiment, the insulating resin layer can include 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 of the polyimide layers (preferably the base film layer) is formed using the non-thermoplastic polyimide of the above embodiment. preferable. For example, when two insulating resin layers are used, P1 is a non-thermoplastic polyimide layer, P2 is a thermoplastic polyimide layer, and M2 is a wiring layer. P1 / P2 / M2 are preferably laminated in this order. Here, P1 is a base film layer formed using the non-thermoplastic polyimide of the above embodiment. P2 may be made of polyimide other than the above embodiment.

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

  Hereinafter, a method for manufacturing a circuit board according to the present embodiment will be specifically described by taking as an example a combination of a casting method and a subtractive method.

First, the manufacturing method of the metal-clad laminate of the present embodiment can include the following steps (1) to (3).
Step (1):
Step (1) is a step of obtaining a resin solution of polyamic acid that is a precursor of the polyimide of the above embodiment. As described above, this step is performed by reacting a tetracarboxylic dianhydride containing pyromellitic dianhydride and a diamine component containing dimer acid diamine, diamine A and diamine B in an appropriate solvent. be able to.

Step (2):
Step (2) is a step of applying a polyamic acid resin solution onto a metal foil to be a metal layer to form a coating film. The metal foil can be used in the form of a cut sheet, a roll, or an endless belt. In order to obtain productivity, it is efficient to use a roll-like or endless belt-like form so that continuous production is possible. Furthermore, the copper foil is preferably in the form of a roll that is formed in a long shape from the viewpoint of expressing the effect of improving the accuracy of the wiring pattern on the circuit board.

  The coating film can be formed by directly applying the polyamic acid resin solution on the metal foil or by applying the solution on the polyimide layer supported by the metal foil and then drying. The method of applying is not particularly limited, and it is possible to apply with a coater such as a comma, die, knife, lip or the like.

  The polyimide layer may be a single layer or a plurality of layers. In the case where a plurality of polyimide layers are used, other precursors can be sequentially applied on the precursor layers made of different components. When the precursor layer is composed of three or more layers, the precursor having the same configuration may be used twice or more. A two-layer or a single layer having a simple layer structure is preferable because it can be advantageously obtained industrially. The thickness of the precursor layer (after drying) is, for example, in the range of 3 to 100 μm, preferably in the range of 3 to 50 μm.

  When multiple polyimide layers are used, the precursor film is formed so that the base film layer is a non-thermoplastic polyimide layer made of the polyimide of the above embodiment, and the polyimide layer in contact with the metal layer is a thermoplastic polyimide layer. It is preferable to do. By using thermoplastic polyimide, adhesion with the metal layer can be improved. Such a thermoplastic polyimide preferably has a glass transition temperature (Tg) of 360 ° C. or lower, more preferably 200 to 320 ° C.

  It is also possible to once imidize a single layer or a plurality of precursor layers into a single layer or a plurality of polyimide layers, and further form a precursor layer thereon.

Step (3):
Step (3) is a step of forming an insulating resin layer by heat-treating the coating film to imidize it. The imidization method is not particularly limited, and for example, heat treatment such as heating for 1 to 60 minutes under a temperature condition in the range of 80 to 400 ° C. is suitably employed. In order to suppress the oxidation of the metal layer, heat treatment in a low oxygen atmosphere is preferable. Specifically, the heat treatment is performed in an inert gas atmosphere such as nitrogen or a rare gas, in a reducing gas atmosphere such as hydrogen, or in a vacuum. Is preferred. By the heat treatment, the polyamic acid in the coating film is imidized to form polyimide.

  As described above, a metal-clad laminate having a polyimide layer (single layer or multiple layers) and a metal layer can be produced.

  The circuit board manufacturing method of the first embodiment can further include the following step (4) in addition to the steps (1) to (3).

Step (4):
Step (4) is a step of forming a wiring layer by patterning the metal foil of the metal-clad laminate. In this step, the circuit layer is obtained by forming a pattern by etching the metal layer into a predetermined shape and processing it into a wiring layer. Etching can be performed by any method using, for example, photolithography.

  In the above description, only the characteristic steps of the circuit board manufacturing method have been described. That is, when manufacturing a circuit board, processes other than the above normally performed, for example, processes such as through-hole processing in a previous process, terminal plating in a subsequent process, and external processing can be performed according to a conventional method.

  As described above, the polyimide of the above embodiment has excellent dimensional stability by heat treatment and has a low dielectric loss tangent. Therefore, by using the polyimide of the present embodiment, a metal-clad laminate having excellent impedance matching can be formed. In addition, by using the polyimide according to the above-described embodiment, electrical signal transmission characteristics can be improved and reliability can be improved in a circuit board typified by FPC.

  The features of the present invention will be described more specifically with reference to examples. 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 coefficient of thermal expansion (CTE)]
The coefficient of thermal expansion was 30 ° C. to 250 ° C. with a constant temperature increase rate while applying a 5.0 g load using a thermomechanical analyzer (trade name: 4000SA) made of a polyimide film having a size of 3 mm × 20 mm. Then, the temperature was further maintained at that temperature for 10 minutes, followed by cooling at a rate of 5 ° C./minute, and an average thermal expansion coefficient (linear thermal expansion coefficient) from 240 ° C. to 100 ° C. was determined.

[Measurement of glass transition temperature (Tg)]
The glass transition temperature is 5 mm × 20 mm using a viscoelasticity measuring device (DMA: manufactured by TA Instruments Co., Ltd., trade name: RSA3). The temperature at which the elastic modulus change was maximum (the tan δ change rate was the largest) was evaluated as the glass transition temperature.

[Measurement of peel strength]
Peel strength was measured using a tensilon tester (trade name: Strograph VE-10, manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the double-sided tape was applied to the resin layer side of a 1 mm wide sample (laminate composed of substrate / resin layer). Was fixed to the aluminum plate, and the force for peeling the resin layer and the substrate in the 180 ° direction at a speed of 50 mm / min was determined.

[Measurement of dielectric constant and dissipation factor]
The dielectric constant and dielectric loss tangent were determined by the following method 1 (cavity resonator perturbation method) or method 2 (parallel plate method).
Method 1) Using a cavity resonator perturbation method dielectric constant evaluation apparatus (manufactured by Agilent, trade name: Vector Network Analyzer E8363B), the dielectric constant and dielectric loss tangent of a resin sheet (cured resin sheet) at a predetermined frequency were measured. . In addition, the resin sheet used for the measurement was left for 24 hours under the conditions of temperature; 24-26 ° C., humidity: 45-55%.
Method 2) The dielectric constant and dielectric loss tangent of the resin sheet (cured resin sheet) at a predetermined frequency were measured using a parallel plate method dielectric constant evaluation apparatus (trade name; Material Analyzer E4991A, manufactured by Agilent). In addition, the resin sheet used for the measurement was left for 1 hour under the conditions of temperature; 30 to 85 ° C., humidity; 30 to 85%.

Abbreviations used in Examples and Comparative Examples indicate the following compounds.
DDA: Dimer acid type diamine (trade name; PRIAMINE 1074, carbon number: 36, amine value: 210 mgKOH / g, content of dimer component: 95% by weight or more)
m-TB: 2,2′-dimethyl-4,4′-diaminobiphenyl TPE-R: 1,3-bis (4-aminophenoxy) benzene TPE-Q: 1,4-bis (4-aminophenoxy) benzene APB : 1,3-bis (3-aminophenoxy) benzene BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl] propane PMDA: pyromellitic dianhydride BPDA: 3, 3 ′, 4, 4 '-Biphenyltetracarboxylic dianhydride DMAc: N, N-dimethylacetamide

Synthesis example 1
In a 300 ml separable flask, 2.578 g DDA (4.82 mmol), 1.410 g TPE-R (4.82 mmol), 15.022 g m-TB (70.76 mmol), 212.5 g DMAc. The mixture was stirred and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.661 g of BPDA (15.84 mmol) and 13.821 g of PMDA (63.36 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution A. The resulting polyamic acid solution A had a viscosity of 8,900 cP and a weight average molecular weight (Mw) of 114,000.

Synthesis example 2
In a 300 ml separable flask, 2.558 g DDA (4.79 mmol), 1.866 g TPE-R (6.38 mmol), 14.568 g m-TB (68.62 mmol), 212.5 g DMAc. The mixture was stirred and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.625 g of BPDA (15.72 mmol) and 13.715 g of PMDA (62.88 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution B. The resulting polyamic acid solution B had a viscosity of 9,500 cP and a weight average molecular weight (Mw) of 120,000.

Synthesis example 3
In a 300 ml separable flask, 2.152 g DDA (4.03 mmol), 2.355 g TPE-R (8.05 mmol), 14.534 g m-TB (68.46 mmol), 212.5 g DMAc. The mixture was stirred and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.669 g of BPDA (15.87 mmol) and 13.844 g of PMDA (63.47 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution C. The resulting polyamic acid solution C had a viscosity of 13,700 cP and a weight average molecular weight (Mw) of 126,000.

Synthesis example 4
In a 300 ml separable flask, 1.316 g DDA (2.46 mmol), 2.401 g TPE-R (8.21 mmol), 15.169 g m-TB (71.45 mmol), 212.5 g DMAc. The mixture was stirred and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.760 g of BPDA (16.18 mmol) and 14.116 g of PMDA (64.72 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution D. The resulting polyamic acid solution D had a viscosity of 10,000 cP and a weight average molecular weight (Mw) of 112,000.

Synthesis example 5
To a 300 ml separable flask, 7.056 g of TPE-R (24.1 mmol), 11.957 g of m-TB (56.24 mmol), and 212.5 g of DMAc were added and stirred at room temperature under a nitrogen stream. . After sufficiently stirring, 4.664 g of BPDA (15.83 mmol) and 13.824 g of PMDA (63.31 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution E. The resulting polyamic acid solution E had a viscosity of 6,200 cP and a weight average molecular weight (Mw) of 111,000.

Synthesis Example 6
A 300 ml separable flask was charged with 4.786 g of TPE-R (16.35 mmol), 13.904 g of m-TB (65.40 mmol), and 212.5 g of DMAc, and stirred at room temperature under a nitrogen stream. . After sufficiently stirring, 4.746 g of BPDA (16.10 mmol) and 14.065 g of PMDA (64.42 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution F. The resulting polyamic acid solution F had a viscosity of 19,600 cP and a weight average molecular weight (Mw) of 155,000.

Synthesis example 7
A 300 ml separable flask was charged with 2.396 g of TPE-R (8.18 mmol), 15.659 g of m-TB (73.65 mmol), and 212.5 g of DMAc, and stirred at room temperature under a nitrogen stream. . After sufficiently stirring, 7.126 g of BPDA (24.18 mmol) and 12.320 g of PMDA (56.43 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution G. The resulting polyamic acid solution G had a viscosity of 28,300 cP and a weight average molecular weight (Mw) of 146,000.

Synthesis Example 8
A 300 ml separable flask was charged with 2.491 g DDA (4.66 mmol), 3.189 g BAPP (7.77 mmol), 13.854 g m-TB (65.26 mmol), 212.5 g DMAc. The mixture was stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.503 g of BPDA (15.30 mmol) and 13.353 g of PMDA (61.22 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution H. The resulting polyamic acid solution H had a viscosity of 1,900 cP and a weight average molecular weight (Mw) of 77,000.

Synthesis Example 9
In a 300 ml separable flask, 1.316 g DDA (2.46 mmol), 2.401 g TPE-R (8.21 mmol), 15.169 g m-TB (71.45 mmol), 212.5 g DMAc. The mixture was stirred and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.760 g of BPDA (16.18 mmol) and 14.116 g of PMDA (64.72 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution I. The resulting polyamic acid solution I had a viscosity of 10,000 cP and a weight average molecular weight (Mw) of 112,000.

Synthesis Example 10
To a 300 ml separable flask, 7.056 g of TPE-R (24.1 mmol), 11.957 g of m-TB (56.24 mmol), and 212.5 g of DMAc were added and stirred at room temperature under a nitrogen stream. . After sufficiently stirring, 4.664 g of BPDA (15.83 mmol) and 13.824 g of PMDA (63.31 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution J. The resulting polyamic acid solution J had a viscosity of 6,200 cP and a weight average molecular weight (Mw) of 111,000.

Synthesis Example 11
A 300 ml separable flask was charged with 4.786 g of TPE-R (16.35 mmol), 13.904 g of m-TB (65.40 mmol), and 212.5 g of DMAc, and stirred at room temperature under a nitrogen stream. . After sufficiently stirring, 4.746 g of BPDA (16.10 mmol) and 14.065 g of PMDA (64.42 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution K. The resulting polyamic acid solution K had a viscosity of 19,600 cP and a weight average molecular weight (Mw) of 155,000.

Synthesis Example 12
A 300 ml separable flask was charged with 2.396 g of TPE-R (8.18 mmol), 15.659 g of m-TB (73.65 mmol), and 212.5 g of DMAc, and stirred at room temperature under a nitrogen stream. . After sufficiently stirring, 7.126 g of BPDA (24.18 mmol) and 12.320 g of PMDA (56.43 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution L. The resulting polyamic acid solution L had a viscosity of 28,300 cP and a weight average molecular weight (Mw) of 146,000.

Synthesis Example 13
A 300 ml separable flask was charged with 4.228 g of DDA (7.91 mmol), 15.120 g of m-TB (71.22 mmol), and 212.5 g of DMAc, and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 4.578 g of BPDA (15.56 mmol) and 13.574 g of PMDA (62.23 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution M. The obtained polyamic acid solution M had a viscosity of 12,800 cP and a weight average molecular weight (Mw) of 115,000.

Synthesis Example 14
A 300 ml separable flask was charged with 10.681 g of BAPP (26.02 mmol), 1.127 g of DDA (2.11 mmol) and 132 g of DMAc, and stirred at room temperature under a nitrogen stream. After sufficiently stirring, 0.411 g of BPDA (1.40 mmol) and 5.782 g of PMDA (26.51 mmol) were added and stirred at room temperature for 4 hours to obtain a polyamic acid solution N. The viscosity of the obtained polyamic acid solution N was 2,700 cP, and the weight average molecular weight (Mw) was 233,000.

Example 1
Polyamic acid solution A was uniformly applied onto an electrolytic copper foil having a thickness of 12 μm so that the thickness after heat treatment was about 25 μm, and the solvent was removed by heating and drying at 120 ° C. for 3 minutes. Thereafter, the temperature was raised stepwise from 130 ° C. to 360 ° C., and imidization was performed by heat treatment (heat treatment condition 1) for a total of about 20 minutes. About the obtained copper clad laminated board, the copper foil was etched away and the polyimide film was obtained. Further, a film was produced in the same manner as described above except that the heat treatment after drying was stepwise raised from 130 ° C. to 360 ° C. and imidization was performed by a heat treatment (heat treatment condition 2) of about 180 minutes in total. The characteristics of the film obtained by the two heat treatment conditions are shown in the table.

Example 2
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution B was used. The properties of the obtained film are shown in the table.

Example 3
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution C was used. The properties of the obtained film are shown in the table.

Example 4
The polyamic acid solution D was uniformly applied onto an electrolytic copper foil having a thickness of 12 μm so that the thickness after heat treatment was about 25 μm, and the solvent was removed by heating and drying at 120 ° C. for 3 minutes. Thereafter, the temperature was raised stepwise from 130 ° C. to 360 ° C., and imidization was performed by heat treatment (heat treatment condition 1) for a total of about 20 minutes. About the obtained copper clad laminated board, the copper foil was etched away and the polyimide film was obtained. The properties of the obtained film are shown in the table.

Example 5
A film was obtained in the same manner as in Example 4 except that the polyamic acid solution E was used. The properties of the obtained film are shown in the table.

Example 6
A film was obtained in the same manner as in Example 4 except that the polyamic acid solution F was used. The properties of the obtained film are shown in the table.

Example 7
A film was obtained in the same manner as in Example 4 except that the polyamic acid solution G was used. The properties of the obtained film are shown in the table.

Example 8
A film was obtained in the same manner as in Example 4 except that the polyamic acid solution H was used. The properties of the obtained film are shown in the table.

Comparative Example 1
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution D was used. The properties of the obtained film are shown in the table.

Comparative Example 2
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution E was used. The properties of the obtained film are shown in the table.

Comparative Example 3
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution F was used. The properties of the obtained film are shown in the table.

Comparative Example 4
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution G was used. The properties of the obtained film are shown in the table.

Comparative Example 5
A film was obtained in the same manner as in Example 1 except that the polyamic acid solution M was used. The properties of the obtained film are shown in the table.

Test example 1
A polyamic acid solution N was uniformly applied onto an electrolytic copper foil having a thickness of 12 μm so that the thickness after the heat treatment was about 4 μm, and the solvent was removed by heating and drying at 120 ° C. for 1 minute and 30 seconds. On top of that, the polyamic acid solution A was uniformly applied so that the thickness after heat treatment was about 42 μm, and the solvent was removed by heating and drying at 120 ° C. for 5 minutes. Furthermore, the polyamic acid solution N was uniformly applied so that the thickness after the heat treatment was about 4 μm, and the solvent was removed by heating and drying at 120 ° C. for 1 minute and 30 seconds. Thereafter, the temperature was raised stepwise from 130 ° C. to 360 ° C. to perform imidization. About the obtained copper clad laminated board, the copper foil was etched away and the polyimide film was obtained. The dimensional change rate of the obtained film is shown in the table.

Test example 2
A polyimide film was obtained in the same manner as in Reference Example 7 except that the polyamic acid M was used in place of the polyamic acid solution A. The dimensional change rate of the obtained film is shown in the table.

  From Table 3, by including dimer acid type diamine as a raw material of polyimide, low dielectric constant and low dielectric loss tangent are obtained, and it is difficult to be affected by dielectric loss tangent due to heat treatment conditions. However, if too much dimer acid type diamine is added, the difference between the dimensional change rate after etching and the dimensional change rate after heating becomes large, and it is difficult to keep both within the preferable range (within ± 0.10).

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible.

Claims (5)

A polyimide obtained by reacting a tetracarboxylic dianhydride component and a diamine component, the following conditions (i) to (iv);
i) containing pyromellitic dianhydride in the range of 70 to 100 mol% in all tetracarboxylic dianhydrides;
ii) The dimer acid type diamine in which the two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups in the total diamine within a range of 4 to 8 mol%;
iii) containing diamine A represented by the following formula (1) in the range of 76 to 92 mol% in all diamines;

[R represents an alkyl group having 3 or less carbon atoms, —CF ₃ , or —CH═CH ₂ ]
iv) In all diamines, the diamine B represented by the following formula (2) is contained within a range of 4 to 16 mol%;

[Wherein X means the following structure]

Polyimide characterized by satisfying   The polyimide according to claim 1, wherein the imide group concentration is in the range of 31 to 33% by weight. A resin film having a single layer or a plurality of polyimide layers,
At least 1 layer of the said polyimide layer is comprised by the polyimide of Claim 1 or 2, The resin film characterized by the above-mentioned.   A metal-clad laminate comprising an insulating resin layer and a metal layer, wherein the insulating resin layer comprises the resin film according to claim 3.   A circuit board obtained by processing the metal layer of the metal-clad laminate according to claim 4 into a wiring.