JP6991712B2 - Colored polyimide film, coverlay film, copper-clad laminate and circuit board - Google Patents

Description

The present invention relates to a colored polyimide film, a coverlay film, a copper-clad laminate and a circuit board.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, flexible printed circuit boards (FPCs) are used as electronic components that are thin, lightweight, flexible, and have excellent durability even after repeated bending. Demand for Flexible Printed Circuits) is increasing. Since FPC can be mounted three-dimensionally and at high density even in a limited space, its use is expanded to, for example, wiring of moving parts in electronic devices such as HDDs and personal digital assistants, and parts such as cables and connectors. I'm doing it.

In recent years, as the performance of electronic devices has improved, it is also necessary to cope with the increase in the frequency of transmission signals in FPCs. 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 required to reduce the transmission loss of the FPC.

By the way, in an electronic device using an FPC, the reflected light from the surface of the coverlay film for protecting the wiring portion of the FPC and the transmitted light via the FPC may adversely affect the performance of the electronic device. Therefore, the FPC or the coverlay film may be required to have a light-shielding property. In addition, when multiple wirings are identified inside an electronic device or the housing of the electronic device is transparent, it is convenient to color the FPC or coverlay film, and designability is required. In some cases.

As the insulating resin layer and the coverlay film in the FPC, a polyimide film having flexibility, heat resistance, insulating property and the like is preferably used. Then, in order to impart light-shielding property and design property to the polyimide film, a pigment is contained.

For example, Patent Document 1 proposes a pigment-added polyimide film containing two or more kinds of pigments and having a glossiness and a coefficient of thermal expansion adjusted within a predetermined range. Further, Patent Document 2 proposes a black polyimide film in which the moisture permeability is adjusted to a predetermined value in order to improve the deterioration of electrical insulation and electrical reliability due to the addition of a pigment such as carbon black.

Japanese Patent Application No. 2014-141575 Japanese Patent Application No. 2016-47863

In the above-mentioned conventional technique, by adding a pigment to the polyimide film, a light-shielding property, a design property, etc. are imparted, and a device for compensating for a decrease in electrical insulating property due to the addition of the pigment is made. However, the influence of the addition of the pigment on the transmission loss of the high frequency signal is not considered at all. Dielectric properties (dielectric constant, dielectric loss tangent) may deteriorate by blending a polyimide film with a pigment, and when the polyimide film containing a pigment is applied to an insulating resin layer or a coverlay film in an FPC, a high frequency signal is obtained. There is concern about the impact on transmission.

Therefore, an object of the present invention is to provide a colored polyimide film capable of achieving both colorability and low dielectric property.

As a result of diligent research in view of the above circumstances, it was found that the dielectric property of the polyimide film can be improved by blending a benzodifuranone derivative as a colorant, and the present invention has been completed.
That is, the colored polyimide film of the present invention contains a benzodifuranone derivative.

In the colored polyimide film of the present invention, the benzodifuranone derivative is represented by the following formula (1a) or (1b), and may be colored black.

In the formulas (1a) and (1b), R ₁ and R ₆ are independently hydrogen atoms or fluorine atoms, and R ₂ , R ₄ , R ₅ , R ₇ , R ₉ and R ₁₀ are hydrogen. It is an atom, a fluorine atom or a chlorine atom, and R ₃ and R ₈ are a hydrogen atom, a bromine atom, a chlorine atom, NO ₂ , OCH ₃ , OC ₂ H ₅ , CH ₃ , C ₂ H ₅ , N (CH ₃ ). ₂ , N (CH ₃ ) (C ₂ H ₅ ), N (C ₂ H ₅ ) ₂ , α-naphthyl, β-naphthyl or SO _3- ^, R ₁ is the same as R ₆ , R ₂ is R ₇ Same as, R ₃ is the same as R ₈ , R ₄ is the same as R ₉ , and / or R ₅ is the same as R ₁₀ .

The colored polyimide film of the present invention has the following mathematical formula (a),
E1 = √ε1 × Tanδ1 ・ ・ ・ (a)
[Here, ε1 indicates the dielectric constant at 10 GHz by the split-post derivative (SPDR) resonator, and Tan δ1 indicates the dielectric loss tangent at 10 GHz by the split-post derivative (SPDR) resonator].
The E1 value, which is an index indicating the dielectric property calculated based on the above, may be 0.02 or less.

The coverlay film of the present invention is a coverlay film including a polyimide insulating layer (A) and a polyimide adhesive layer (B) provided on one surface of the polyimide insulating layer (A). The coverlay film of the present invention is characterized in that the polyimide insulating layer (A) and / or the polyimide adhesive layer (B) is made of the colored polyimide film.

The circuit board of the present invention includes the coverlay film.

The copper-clad laminate of the present invention is a copper-clad laminate having an insulating resin layer and a copper foil on at least one surface of the insulating resin layer, and the insulating resin layer is any of the above colored polyimide films. It is characterized by including a layer.

The circuit board of the present invention is formed by processing the copper foil of the copper-clad laminate into wiring.

Since the colored polyimide film of the present invention contains a benzodifuranone derivative as a colorant, it has light-shielding properties, concealing properties, and design properties, and has improved dielectric properties.
Therefore, by applying the colored polyimide film of the present invention to an insulating resin layer, a coverlay film, etc. in an FPC, an FPC having light-shielding properties, concealing properties, and design properties, and capable of transmitting high-frequency signals can be obtained. Can be provided.
Further, the FPC using the colored polyimide film of the present invention can block the reflected light from the surface of the coverlay film and the transmitted light via the FPC, and has excellent identification, so that the reliability of the electronic device equipped with the FPC is excellent. Also contributes to the improvement of.

Hereinafter, embodiments of the present invention will be described.
[Colored polyimide film]
The colored polyimide film according to this embodiment contains a benzodifuranone derivative. The polyimide constituting the colored polyimide film means a resin composed of a polymer having an imide group in its molecular structure, such as polyimide, polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, and polybenzimidazoleimide. The benzodifuranone derivative is a pigment that colors a polyimide film into a color such as black or deep red. Among the benzodifuranone derivatives, those represented by the following formula (1a) or (1b) are preferable as those expressing black color.

In the formulas (1a) and (1b), R ₁ and R ₆ are independently hydrogen atoms or fluorine atoms, and R ₂ , R ₄ , R ₅ , R ₇ , R ₉ and R ₁₀ are hydrogen. It is an atom, a fluorine atom or a chlorine atom, and R ₃ and R ₈ are a hydrogen atom, a bromine atom, a chlorine atom, NO ₂ , OCH ₃ , OC ₂ H ₅ , CH ₃ , C ₂ H ₅ , N (CH ₃ ). ₂ , N (CH ₃ ) (C ₂ H ₅ ), N (C ₂ H ₅ ) ₂ , α-naphthyl, β-naphthyl or SO _3- ^, R ₁ is the same as R ₆ , R ₂ is R ₇ Same as, R ₃ is the same as R ₈ , R ₄ is the same as R ₉ , and / or R ₅ is the same as R ₁₀ .

The benzodifuranone derivative represented by the formula (1a) or (1b) can color the polyimide film black and also contributes to the improvement of its dielectric properties (lower dielectric constant, lower dielectric loss tangent).

The content of the benzodifuranone derivative in the colored polyimide film is preferably in the range of 1 to 20 parts by weight, more preferably in the range of 1 to 10 parts by weight with respect to 100 parts by weight of the polyimide. If the content of the benzodifuranone derivative is less than 1 part by weight, coloring may be insufficient or the improvement of the dielectric property may be insufficient, and if it exceeds 20 parts by weight, the polyimide film becomes fragile. Or, the electrical insulation may be reduced.

For example, the benzodifuranone derivative represented by the formula (1a) or (1b) is contained in an amount of preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyimide. The black polyimide film to be used is the following formula (a),
E1 = √ε1 × Tanδ1 ・ ・ ・ (a)
[Here, ε1 indicates the permittivity at 10 GHz by the split post derivative (SPDR) resonator, and Tan δ1 indicates the dielectric loss tangent at 10 GHz by the SPDR resonator].
The E1 value, which is an index indicating the dielectric property calculated based on the above, is 0.02 or less.

When the colored polyimide film of the present embodiment is a black polyimide film containing a benzodifuranone derivative represented by the formula (1a) or (1b), in order to effectively exhibit light-shielding property, concealing property, design property and the like. In addition, a black pigment other than the benzodifuranone derivative represented by the formula (1a) or (1b), a matte pigment that suppresses the gloss of the surface of the black polyimide film, and the like can be contained as long as the effect of improving the dielectric property is not impaired. ..

Examples of black pigments other than benzodifuranone derivatives include organic pigments such as aniline black and perylene black, carbon black, iron manganese bismuth black, iron chrome black, cobalt iron chrome black, iron manganese oxide spinel black, and copper chrome manganese black. , Manganese bismuth black, manganese ittrium black, copper chromate spinel black, hematite, magnetite, mica-like iron oxide, titanium black and other inorganic pigments.

The content of the black pigment other than the benzodifuranone derivative is preferably in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the polyimide as the total amount with the benzodifuranone derivative represented by the formula (1a) or (1b). It is more preferably in the range of 1 to 10 parts by weight. If the total amount of the benzodifuranone derivative represented by the formula (1a) or (1b) and the black pigment is less than 1 part by weight, sufficient black color may not be developed, and if it exceeds 20 parts by weight, the polyimide film becomes fragile. Or the electrical insulation may be reduced.

Examples of the matte pigment include silica, mica, titanium oxide, boron nitride, aluminum nitride, aluminum oxide, magnesium oxide, calcium phosphate and the like. The matte pigment is preferably contained in the range of, for example, 3 to 12 parts by weight with respect to 100 parts by weight of the polyimide in order to suppress the glossiness of the black polyimide film to, for example, 40% or less, preferably 30% or less. .. If the content of the matte pigment is less than 3 parts by weight, the suppression of glossiness may be insufficient, and if it exceeds 12 parts by weight, the strength of the black polyimide film may be lowered.

When a benzodifuranone derivative that develops a color other than black (for example, deep red) is used, other pigments or matte pigments can be used in combination in the same manner.

[Manufacturing of colored polyimide film]
The colored polyimide film of the present embodiment can be produced by reacting an acid anhydride component and a diamine component in a solvent to generate a precursor, and then heating and closing the ring. For example, the acid anhydride component and the diamine component are dissolved in an organic solvent in approximately equal molar amounts, and the mixture is stirred at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours to carry out a polymerization reaction to obtain a polyimide precursor. Polyimide is obtained. Here, the acid anhydride and the diamine component can be appropriately selected depending on the purpose of use of the colored polyimide film. In the reaction, the reaction components are dissolved in the organic solvent 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. Examples of the organic solvent used in 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 aromatic hydrocarbons such as xylene and toluene can be used in combination. The amount of the organic solvent used is not particularly limited, but is adjusted so 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 use it.

The synthesized precursor is usually advantageous for use as a reaction solvent solution, but can be concentrated, diluted or replaced with other organic solvents as needed. In addition, precursors are generally excellent in solvent solubility and are therefore used advantageously. The benzodifuranone derivative as a colorant may be mixed in the above-mentioned organic solvent used for synthesizing the precursor polyamic acid, or after synthesizing the polyamic acid, the benzodifuranone derivative may be dispersed in the polyamic acid. The liquid may be mixed. The method for imidizing the precursor 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.

The colored polyimide film obtained as described above is preferably applicable as a coverlay film in a circuit board typified by FPC, or as an insulating resin layer supporting wiring in a circuit board. For example, the colored polyimide film of the present embodiment is a copper-clad laminate having an insulating resin layer and a copper foil on at least one surface of the insulating resin layer, and one or a plurality of layers constituting the insulating resin layer. Can be applied as. Then, a circuit board can be manufactured by processing the copper foil of the copper-clad laminate into wiring.

[Coverlay film]
Next, a case where the colored polyimide film of the present embodiment is applied to a coverlay film of a circuit board will be described as an example. The coverlay film is composed of a polyimide insulating layer (A) and a polyimide adhesive layer (B) provided on one surface of the polyimide insulating layer (A). The colored polyimide film containing the benzodifuranone derivative can be applied to both the polyimide insulating layer (A) and the polyimide adhesive layer (B).

The coverlay film may have a mold release material layer attached to the surface on the polyimide adhesive layer (B) side. The material of the release material is not particularly limited as long as it can be peeled off without impairing the form of the coverlay film, but for example, a resin film such as polyethylene terephthalate, polyethylene, polypropylene, or these resin films are placed on paper. A laminated product or the like can be used.

Next, the polyimide insulating layer (A) and the polyimide adhesive layer (B) will be described in detail.

[Polyimide Insulation Layer (A)]
The resin used for the polyimide insulating layer (A) is a polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride component with a diamine component containing an aliphatic diamine and / or an aromatic diamine. Is. Since polyimide is generally produced by reacting acid anhydride with diamine, a specific example of polyimide can be understood by explaining acid anhydride and diamine. Hereinafter, a polyimide preferable as a material for the polyimide insulating layer (A) will be described with acid anhydride and diamine.

<Acid anhydride>
As the acid anhydride of the raw material of the polyimide used for the polyimide insulating layer (A), pyromellitic anhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetra Carous acid dianhydride, 3,3', 4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid anhydride are 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 acid 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) sulfonate 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 hydride, 2,3,6,7-anthracene tetracarboxylic dianhydride Anhydride, 2,2-bis (3,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride Anhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetra Carboxydic 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 acid dianhydride, 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-2,3,4,5-Tetracarboxylic acid dianhydride, 4,4'- Bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride or the like can also be used.

<Diamine>
As the diamine component of the raw material of the polyimide used for the polyimide insulating layer (A), a dimer acid type diamine having two terminal carboxylic acid groups of dimer acid substituted with a primary aminomethyl group or an amino group, paraphenylenediamine, 4 , 4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 4 , 4'-diaminodiphenyl ether, 2'-methoxy-4,4'-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2 '-Bis [4- (4-aminophenoxy) phenyl] propane, 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] Pulmonates, 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'-diaminodiphenylether, 3,3-diaminodiphenylether, 3,4'-diaminodiphenylether, benzidine , 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4''-diamino-p-terphenyl, 3,3''-diamino-p-terphenyl, m-phenylenediamine, p- Phenylene diamine, 2,6-diaminopyridine, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4'-[1,4-phenylene bis (1) -Methylethylidene)] bisaniline, 4,4'-[1,3-phenylenebis (1-methylethylidene)] bisaniline, bis (p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) Ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1 , 5-Diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene- 2,5-diamine, m-xylylene diamine, p-xylylene diamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, etc. Can be used.

As the acid anhydride and the diamine, only one kind thereof may be used, or two or more kinds thereof may be used in combination. Further, diamines and acid anhydrides other than the above can also be used. Thermal expansion, adhesiveness, glass transition temperature, etc. can be controlled by selecting the types of acid anhydride and diamine, and the molar ratio of each when two or more types of acid anhydride or diamine are used. ..

The polyimide constituting the polyimide insulating layer (A) preferably has an imide group concentration of 36% by weight or less, more preferably 35% by weight or less. Here, the "imide group concentration" means a value obtained by dividing the molecular weight of the imide base portion (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 36% by weight, the flame retardancy of the polyimide is lowered, and the dielectric property is also deteriorated due to the increase in polar groups.

The polyimide constituting the polyimide insulating layer (A) can be produced by reacting the acid anhydride component and the diamine component in a solvent to generate a precursor, and then heating and closing the ring. The step of synthesizing the precursor from the acid anhydride component and the diamine component and imidizing the precursor can be carried out according to the method described in the above-mentioned "Production of Colored Polyimide Film".

The polyimide insulating layer (A) exhibits a function as a protective film, and is preferably 12 μm or more from the viewpoint of transportability during manufacturing and coating of the adhesive layer, and has a dielectric property as a coverlay film. In order to avoid deterioration, it is preferably in the range of 30 μm or less.

From the viewpoint of heat resistance, the polyimide insulating layer (A) preferably has a glass transition temperature (Tg) of 280 ° C. or higher, more preferably 300 ° C. or higher. Further, from the viewpoint of suppressing warpage when the coverlay film is bonded to the FPC, the heat ray expansion coefficient of the polyimide insulating layer (A) is in the range of 1 to 30 [ppm / K], preferably 1 to 25 [. It is preferably in the range of [ppm / K], more preferably in the range of 15 to 25 [ppm / K].

Further, the resin used for the polyimide insulating layer (A) includes other curing resin components such as a plasticizer and an epoxy resin, a curing agent, a curing accelerator, a coupling agent, a filler, a solvent, and a flame retardant as optional components. Etc. can be appropriately blended. However, some plasticizers contain a large amount of polar groups, which may promote the diffusion of copper from the copper wiring. Therefore, it is preferable not to use the plasticizer as much as possible.

[Polyimide adhesive layer (B)]
The resin used for the polyimide adhesive layer (B) is a polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride component with an aliphatic diamine and / or an aromatic diamine. Hereinafter, a polyimide preferable as a material for the polyimide adhesive layer (B) will be described with acid anhydride and diamine.

The resin used for the polyimide adhesive layer (B) is, for example, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), 4,4'-oxydiphthalic acid anhydride as a raw material acid anhydride. Stuff (ODPA, also known as; 5,5'-oxybis-1,3-isobenzofrangion), 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 3,3', 4, 4'-Diphenylsulfone tetracarboxylic acid dianhydride (DSDA), pyromellitic acid dianhydride (PMDA), 5,5'-[1-methyl-1,1-ethanediylbis (1,4-phenylene) bisoxy] bis (Isobenzofuran-1,3-dione) (BISDA), 4,4'-diaminodicyclohexylmethane and the like can be preferably used. These can be used alone or in combination of two or more.

<Alphatic diamine>
The resin used for the polyimide adhesive layer (B) has, as a raw material diamine component, for example, a dimer acid type diamine in which two terminal carboxylic acid groups of dimer acid are replaced with a primary aminomethyl group or an amino group, 1, 4-Diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 2-methyl-1,5-diaminopentane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,3-bis ( Aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 4,4'-methylenebis Diaminoalkanes such as cyclohexylamine, tris (2-aminoethyl) amine, N, N'-bis (2-aminoethyl) -1,3-propanediamine, bis (3-aminopropyl) ethylenediamine, 1,4- Nitrogen atoms such as bis (3-aminopropyl) piperazine, diethylenetriamine, N-methyl-2,2'-diaminodiethylamine, 3,3'-diaminodipropylamine, N, N-bis (3-aminopropyl) methylamine Amines containing, bis (3-aminopropyl) ether, 1,2-bis (2-aminoethoxy) ethane, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxa It is desirable that the main component is amines containing oxygen atoms such as Spiro [5.5] -undecane, and aliphatic diamines such as amines having sulfur atoms such as 2,2'-thiobis (ethylamine). These can be used alone or in combination of two or more.

<Aromatic diamine>
The resin used for the polyimide adhesive layer (B) has 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl as a raw material diamine component. 4'-Diamino-2,2'-bis (trifluoromethyl) biphenyl, 4,4'-diaminodiphenyl ether, 2'-methoxy-4,4'-diaminobenzanilide, 1,4-bis (4-aminophenoxy) ) Benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 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- (4- (4-) Aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-Aminophenoxy)] biphenyl, bis [1- (3-aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, Bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy)] benzophenone, bis [4- (3-aminophenoxy) )] Benzophenone, bis [4,4'-(4-aminophenoxy)] benzanilide, bis [4,4'-(3-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-diethyl Aniline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmetha , 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 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, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4) -Aminophenoxy) benzene, 4,4'-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4'-[1,3-phenylenebis (1-methylethylidene)] bisaniline, bis ( p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) Benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2 , 4-Diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylene diamine, p-xylylene diamine, 2,6-diaminopyridine, 2,5-diamino It may contain aromatic diamines such as pyridine, 2,5-diamino-1,3,4-oxadiazole and piperazine, which may be used alone or in combination of two or more. Further, the aromatic diamine and the aliphatic diamine may be combined.

The resin used for the polyimide adhesive layer (B) can be produced by reacting the acid anhydride component and the diamine component in a solvent to generate a precursor, and then heating and closing the ring. The step of synthesizing the precursor from the acid anhydride component and the diamine component and imidizing the precursor can be carried out according to the method described in the above-mentioned "Production of Colored Polyimide Film".

Further, in the resin used for the polyimide adhesive layer (B), in addition to the polyimide, other curing resin components such as a plasticizer and an epoxy resin, a curing agent, a curing accelerator, a coupling agent, and filling are optional components. Agents, solvents, flame retardants and the like can be appropriately blended. However, some plasticizers contain a large amount of polar groups, which may promote the diffusion of copper from the copper wiring. Therefore, it is preferable not to use the plasticizer as much as possible.

The resin for the polyimide adhesive layer (B) obtained as described above has excellent flexibility and thermoplasticity when the adhesive layer is formed by using the resin, for example, FPC, rigid flex circuit. It has preferable properties as an adhesive for a coverlay film that protects a wiring portion such as a substrate.

[Manufacturing of colored coverlay film]
The colored coverlay film of the present embodiment can be produced, for example, by the method exemplified below.
First, as a first method, an adhesive resin composition to be a polyimide adhesive layer (B) is applied to one side of a film material for a polyimide insulating layer (A) in a solution state (for example, in the form of a varnish containing a solvent). After coating, a colored coverlay film having a polyimide insulating layer (A) and a polyimide adhesive layer (B) can be formed by heat-bonding at a temperature of, for example, 60 to 220 ° C. Here, the benzodifuranone derivative as a colorant can be blended in either one or both of the film material for the polyimide insulating layer (A) and the adhesive resin composition. When a resin component such as a cross-linking agent or an epoxy resin is contained, the cross-linking reaction and the curing reaction of the thermosetting resin can be promoted by utilizing the heat at the time of thermocompression bonding. Further, even if the thermocompression bonding is not sufficient, the thermocompression bonding can be followed by further heat treatment to cause the thermocompression bonding. When the heat treatment is performed after thermocompression bonding, the heat treatment temperature is preferably, for example, 60 to 220 ° C, more preferably 80 to 200 ° C.

Further, as a second method, the adhesive resin composition for the polyimide adhesive layer (B) is applied in a solution state (for example, in the form of a varnish containing a solvent) on an arbitrary substrate, for example, 80 to 80. After drying at a temperature of 180 ° C. and then peeling off, an adhesive film for the polyimide adhesive layer (B) is formed, and this adhesive film is used with a film material for the polyimide insulating layer (A), for example, from 60 to 60. The colored coverlay film of the present embodiment can also be formed by heat-bonding at a temperature of 220 ° C. Here, the benzodifuranone derivative as a colorant can be blended in either one or both of the film material for the polyimide insulating layer (A) and the adhesive resin composition. The polyimide adhesive layer (B) is formed by applying an adhesive resin composition in a solution state on an arbitrary substrate by, for example, screen printing to form a coating film, which is heated at a temperature of, for example, 80 to 180 ° C. It can also be dried in and made into a film for use.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited thereto.

Each characteristic in Examples and Comparative Examples was evaluated as follows.

[Measurement of permittivity and dielectric loss tangent]
The dielectric constant (ε1) and dielectric loss tangent (tanδ1) of the resin sheet at a predetermined frequency were measured using a vector network analyzer (manufactured by Agilent, trade name E8633C) and a split post derivative (SPDR) resonator. From these measured values, E1 = √ε1 × Tanδ1 was calculated. The material used for the measurement was left for 24 hours under the conditions of temperature; 24-26 ° C. and humidity; 45-55%.

[Measurement of coefficient of thermal expansion (CTE)]
A polyimide film having a size of 3 mm × 20 mm was heated from 30 ° C. to 265 ° C. at a constant temperature rise rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). Further, the film was kept 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 240 ° C. to 100 ° C.

[viscosity]
It was determined by measurement using an E-type viscometer.

The abbreviations used in Examples and Comparative Examples indicate the following compounds.
BPDA: 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride PMDA: pyromellitic acid dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl PDA: paraphenylenediamine BTDA: 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride DDA: aliphatic diamine having 36 carbon atoms (manufactured by Claude Japan Co., Ltd., trade name; PRIAMINE1074, amine value; 210 mgKOH / g, cyclic structure and Chain-structured dimerdiamine mixture, content of dimer component; 95% by weight or more)
N-12: Dodecanedioic acid dihydrazide OP935: Aluminum salt of phosphinic acid (manufactured by Clariant Japan Co., Ltd., trade name; Exolit OP935, phosphorus content; 23%, average particle size: 2 μm)
DMAc: N, N-dimethylacetamide black pigment dispersion (i): bis-oxodihydroindoliren-benzodifuranone compound solution (concentration 16% by weight, propylene glycol monomethyl ether acetate (PGMEA) solution)
Black pigment dispersion (ii): carbon black solution (concentration 25% by weight, PGMEA solution)
Copper foil: Rz = 0.35 μm, thickness 12 μm

(Synthesis Example 1)
<Preparation of resin for polyimide insulating layer>
Under a nitrogen stream, 14.00 g of m-TB (0.066 mol) and 170 g of DMAc were placed in a 500 ml separable flask and dissolved by stirring at room temperature. Next, after adding 6.73 g of BPDA (0.023 mol) and 9.26 g of PMDA (0.042 mol), stirring was continued for 3 hours at room temperature to carry out a polymerization reaction to prepare a polyamic acid solution a. did. The solid content concentration in the polyamic acid solution a was 15% by weight, and the solution viscosity was 20,600 cps.

(Synthesis Example 2)
<Preparation of resin for polyimide insulating layer>
Under a nitrogen stream, 12.23 g of m-TB (0.058 mol), 1.10 g of PDA (0.010 mol) and 170 g of DMAc were placed in a 500 ml separable flask and stirred at room temperature. Dissolved. Next, after adding 7.89 g of BPDA (0.027 mol) and 8.78 g of PMDA (0.040 mol), stirring was continued for 3 hours at room temperature to carry out a polymerization reaction to prepare a polyamic acid solution b. did. The solid content concentration in the polyamic acid solution b was 15% by weight, and the solution viscosity was 12,400 cps.

(Comparative Example 1)
To 40 g of the polyamic acid solution a prepared in Synthesis Example 1, 1.2 g of the black pigment dispersion (ii) (2.5 parts by weight with respect to 100 parts by weight of the solid content of the polyamic acid) is blended and defoamed. A polyamic acid solution A containing a black pigment was prepared. A polyamic acid solution A containing a black pigment was uniformly applied to the copper foil so that the thickness after curing was about 25 μm, and then the solvent was removed by a stepwise heat treatment from 85 ° C to 110 ° C, and then 120 ° C. The metal-clad laminate A was prepared by performing a stepwise heat treatment from 1 to 360 ° C. to complete imidization. An opaque black polyimide film A was prepared by removing the copper foil. The characteristics of the black polyimide film A are shown in Table 1.
In Table 1, the numerical value of "black pigment" indicates the weight part of the black pigment with respect to 100 parts by weight of the solid content of the polyamic acid.

(Comparative Example 2)
An opaque black polyimide film B was prepared in the same manner as in Comparative Example 1 using the polyamic acid solution shown in Table 1, the types of the black pigment dispersion liquid, and the addition amounts of each. The characteristics of the black polyimide film B are shown in Table 1.

(Examples 1 to 6)
Opaque black polyimide films 1 to 6 were prepared in the same manner as in Comparative Example 1 using the polyamic acid solution and the type of the black pigment dispersion liquid shown in Table 1 and the addition amounts of each. The appearance of the black polyimide films 1 to 6 was the same as that of the black polyimide film A of Comparative Example 1. Table 1 shows the characteristics of the black polyimide films 1 to 6.

(Reference Examples 1 and 2)
Polyimide films 1a and 2b were prepared in the same manner as in Comparative Example 1 except that the polyamic acid solution shown in Table 1 was used and the black pigment dispersion liquid (ii) was not used. The characteristics of the polyimide films 1a and 2b are shown in Table 1.

As shown in Comparative Examples 1 and 2, when carbon black was used as the black pigment, the dielectric constant and the dielectric loss tangent became high, resulting in impaired dielectric properties.

Compared with Comparative Examples 1 and 2, the black polyimide films 1 to 6 of Examples 1 to 6 using the black pigment dispersion liquid (i) were able to suppress the deterioration of the dielectric properties, and good results were obtained.

<Preparation of resin for polyimide adhesive layer>
(Synthesis Example 3)
Under a nitrogen stream, 44.98 g of BTDA (0.139 mol), 75.02 g of DDA (0.140 mol), 168 g of N-methyl-2-pyrrolidone and 112 g of xylene were placed in a 500 ml separable flask. It was charged and mixed well at 40 ° C. for 30 minutes to prepare a polyamic acid solution. The temperature of this polyamic acid solution was raised to 190 ° C., the mixture was heated and stirred for 4.5 hours, and 112 g of xylene was added to prepare a polyimide adhesive solution c in which imidization was completed. The solid content in the polyimide adhesive solution c was 29.1% by weight, and the viscosity was 7,800 cps. The weight average molecular weight (Mw) of the polyimide adhesive solution c was 87,700.

<Preparation of resin for polyimide adhesive layer>
(Synthesis Example 4)
34.4 g (10 g as a solid content) of the polyimide adhesive solution c prepared in Synthesis Example 3, 1.25 g of N-12 and 2.5 g of Exolit OP935 (manufactured by Clariant Japan Co., Ltd.) are blended and 1.297 g. N-Methyl-2-pyrrolidone and 3.869 g of xylene were added and diluted to prepare a polyimide adhesive solution d.

(Example 7)
The polyimide adhesive solution d prepared in Synthesis Example 5 was applied to one side of the black polyimide film 1 prepared in Example 1 so that the thickness after drying was about 25 μm, and then heated and dried at 80 ° C. for 15 minutes. A black coverlay film CL1 was prepared. Table 2 shows the dielectric properties of the black coverlay film CL1 heated at 180 ° C. for 120 minutes and then adjusted to humidity at 23 ° C. in a 50% environment.

(Examples 8 to 12)
Black coverlay films CL2 to CL6 were prepared in the same manner except that the black polyimide films 2 to 6 prepared in Examples 2 to 6 were used instead of the black polyimide film 1 prepared in Example 1. Table 2 shows the dielectric properties of the black coverlay films CL2 to CL6.

(Reference Examples 3 and 4)
Black coverlay films CL1a and CL2b were prepared in the same manner except that the black polyimide films A and B prepared in Comparative Examples 1 and 2 were used instead of the black polyimide film 1 prepared in Example 1. Table 2 shows the dielectric properties of the black coverlay films CL1a and CL2b.

Although the embodiments of the present invention have been described in detail above for the purpose of illustration, the present invention is not limited to the above embodiments.

Claims (6)

A benzodifuranone derivative represented by the following formula (1a) or (1b) is contained, and the following formula (a),
E1 = √ε1 × Tanδ1 ・ ・ ・ (a)
[Here, ε1 indicates the dielectric constant at 10 GHz by the split-post derivative (SPDR) resonator, and Tan δ1 indicates the dielectric loss tangent at 10 GHz by the split-post derivative (SPDR) resonator].
A colored polyimide film colored in black having an E1 value of 0.02 or less, which is an index showing dielectric properties, calculated based on the above.

[In formulas (1a) and (1b), R ₁ and R ₆ are independently hydrogen atoms or fluorine atoms, and R ₂ , R ₄ , R ₅ , R ₇ , R ₉ and R ₁₀ are It is a hydrogen atom, a fluorine atom or a chlorine atom, and R ₃ and R ₈ are a hydrogen atom, a bromine atom, a chlorine atom, NO ₂ , OCH ₃ , OC ₂ H ₅ , CH ₃ , C ₂ H ₅ , N (CH ₃ ). ) ₂ , N (CH ₃ ) (C ₂ H ₅ ), N (C ₂ H ₅ ) ₂ , α-naphthyl, β-naphthyl or SO _3- ^, R ₁ is the same as R ₆ and R ₂ is R. Same as ₇ , R ₃ is the same as R ₈ , R ₄ is the same as R ₉ , and / or R ₅ is the same as R ₁₀ . ] As a benzodifuranone derivative, a bis-oxodihydroindoliren-benzodifuranone compound is contained, and the following formula (a),
E1 = √ε1 × Tanδ1 ・ ・ ・ (a)
[Here, ε1 indicates the dielectric constant at 10 GHz by the split-post derivative (SPDR) resonator, and Tan δ1 indicates the dielectric loss tangent at 10 GHz by the split-post derivative (SPDR) resonator].
A colored polyimide film colored in black having an E1 value of 0.02 or less, which is an index showing dielectric properties, calculated based on the above. A coverlay film including a polyimide insulating layer (A) and a polyimide adhesive layer (B) provided on one surface of the polyimide insulating layer (A).
A coverlay film characterized in that the polyimide insulating layer (A) and / or the polyimide adhesive layer (B) is composed of the colored polyimide film according to claim 1 or 2. A circuit board provided with the coverlay film according to claim 3. A copper-clad laminate having a copper foil on at least one surface of the insulating resin layer and the insulating resin layer.
A copper-clad laminate comprising the layer of the colored polyimide film according to claim 1 or 2. A circuit board obtained by processing the copper foil of the copper-clad laminate according to claim 5 into wiring.