JP6262691B2 - Solvent-soluble polyimide resin - Google Patents

Description

  The present invention relates to a solvent-soluble polyimide resin useful as an adhesive in a circuit board such as a flexible printed wiring 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 and components such as cables and connectors in electronic devices such as HDDs, DVDs, and mobile phones. It is expanding.

  For the FPC, a coverlay film is used for the purpose of protecting the wiring portion. The coverlay film is formed by laminating a coverlay film material made of a synthetic resin such as a polyimide resin and an adhesive layer. In manufacturing an FPC, a coverlay film material is attached to a circuit board through an adhesive layer by using a method such as hot pressing. The adhesive layer is required to have high adhesion to both the circuit wiring pattern such as copper wiring and the film material for coverlay. As an adhesive for such a coverlay film, it can be processed under relatively low temperature thermocompression bonding conditions, and it has excellent heat resistance and other characteristics, and it can be used as a mixed resin of polyimide resin and epoxy resin having a siloxane unit. In addition, an adhesive resin composition for printed circuit boards, in which one or more plasticizers selected from phosphoric acid ester-based, phthalic acid ester-based, polyester-based and fatty acid ester-based materials are blended has been proposed (for example, Patent Document 1). ).

  In addition, bis (3,4-dicarboxyphenyl) ether dianhydride and a specific structure are used for the purpose of improving the low-temperature sticking property, low hygroscopicity, adhesive force during heating, and PCT resistance of polyimide resins used for adhesive films. A method for producing a polyimide resin in which another acid anhydride and / or another diamine is reacted after reacting with another siloxane diamine has been proposed (for example, Patent Document 2).

JP-A-10-212468 JP 2006-117945 A

  As listed in Patent Documents 1 and 2 above, a polyimide resin containing a siloxane skeleton is suitable for use as an FPC coverlay film adhesive because it has moderate flexibility and heat durability. Yes. However, a polyimide resin containing a siloxane skeleton may contain a cyclic siloxane compound derived from the raw material, and the cyclic siloxane compound is volatilized by long-term exposure to a high-temperature environment and adheres to electrical contacts in electronic components. There is a concern that this may cause poor conduction. Therefore, development of a polyimide resin adhesive that does not use a siloxane compound is desired.

  Furthermore, in-vehicle electronic devices using FPC deployed in the engine room of an automobile are repeatedly placed in a high temperature environment of about 150 ° C., so that the adhesive strength between the FPC coverlay film and the wiring can be maintained over a long period of use. This causes a problem that the wiring protection function is greatly lowered. With the expansion of FPC applications, it is expected that the number of scenes where FPC is used not only in in-vehicle electronic devices but also in severe temperature environments will continue to increase. For this reason, in an FPC used in a high temperature environment, it is strongly required to take measures against a decrease in the adhesive strength of the coverlay film.

  Accordingly, an object of the present invention is to form an adhesive layer that does not generate a volatile component composed of a cyclic siloxane compound and that does not lower the adhesive force between the wiring layer and the coverlay film even in a use environment that is repeatedly exposed to high temperatures. It is to provide a solvent-soluble polyimide resin.

The solvent-soluble polyimide resin for forming an adhesive of the coverlay film of the present invention is a solvent-soluble polyimide resin having a weight average molecular weight in the range of 20,000 to 150,000,
It is obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride and a diamine component containing an aliphatic diamine, and does not contain a siloxane compound as a raw material,
It has the structural unit represented by the following general formula (1) and (2), It is characterized by the above-mentioned.

［式中、Ａｒは芳香族テトラカルボン酸無水物を含む酸無水物から誘導される４価の芳香族基、Ｒ _１ はダイマー酸から誘導される炭素数２４〜４８の範囲内にある脂肪族ジアミンから誘導される２価のジアミン残基、Ｒ _２ は芳香族ジアミンから誘導される２価のジアミン残基をそれぞれ表し、Ａｒ及び／又はＲ _２ 中にはケトン基を含み、ｍ、ｎは各構成単位の存在モル比を示し、ｍは０．５〜１．０の範囲内、ｎは０〜０．５の範囲内である。ただし、Ａｒ中にケトン基を含まない場合は、ｍが１．０、かつ、ｎが０である場合を除く。］

[In the formula, Ar is a tetravalent aromatic group derived from an acid anhydride including an aromatic tetracarboxylic acid anhydride, and R ₁ is an aliphatic group having a carbon number of 24 to 48 derived from dimer acid. Divalent diamine residue derived from diamine, R ₂ represents a divalent diamine residue derived from aromatic diamine, respectively, Ar and / or R ₂ contains a ketone group, m and n are The abundance ratio of each structural unit is shown, m is in the range of 0.5 to 1.0, and n is in the range of 0 to 0.5. However, when Ar does not contain a ketone group, the case where m is 1.0 and n is 0 is excluded. ]

The solvent-soluble polyimide resin for forming an adhesive for a coverlay film of the present invention is such that the aromatic diamine is 4,4′-bis (3-aminophenoxy) benzophenone, 1,3-bis [4- (3-aminophenoxy). ) Benzoyl] benzene, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2′-divinyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2 2,2′-diethyl-4,4′-diaminobiphenyl, 2,2 ′, 6,6′-tetramethyl-4,4′-diaminobiphenyl, 2,2′-diphenyl-4,4′-diaminobiphenyl, And 1 type (s) or 2 or more types chosen from the group which consists of 9,9-bis (4-aminophenyl) fluorene may be sufficient.

In the solvent-soluble polyimide resin for forming an adhesive for a coverlay film of the present invention, the aromatic tetracarboxylic acid anhydride is 3,3 ′, 4,4′-benzophenonetetracarboxylic acid represented by the following formula (3): It may be an acid dianhydride.

The solvent-soluble polyimide resin for forming an adhesive of the coverlay film of the present invention includes N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, It may be soluble in one or more solvents selected from the group consisting of cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, xylene and toluene.

  Since the solvent-soluble polyimide resin of the present invention does not require a siloxane compound as a raw material, generation of a volatile component composed of cyclic siloxane that adversely affects electronic components can be prevented. In addition, the resin film in which the adhesive layer is formed using the solvent-soluble polyimide resin of the present invention is excellent in adhesiveness to the metal wiring layer, and the circuit board used for applications such as a coverlay film and the like The reliability of electronic components can also be improved.

[Crosslinked polyimide resin]
The cross-linked polyimide resin is a cross-linked polyimide resin obtained by reacting (A) a polyimide resin having a ketone group and (B) an amino compound having at least two primary amino groups as functional groups. The component (A) is a polyimide resin obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride and a diamine component containing an aliphatic diamine. The ketone group in the polyimide resin is derived from one or both of the acid anhydride component and the diamine component. The polyimide group has a structure in which the polyimide group is crosslinked by an amino compound by reacting the ketone group in the polyimide resin with the amino group of the component (B) to form a C═N bond.

[(A) Polyimide resin having a ketone group]
Specific examples of the polyimide resin having a ketone group (A) used for the crosslinked polyimide resin include polyimide resins having structural units represented by the following general formulas (1) and (2).

［式中、Ａｒは芳香族テトラカルボン酸無水物を含む酸無水物から誘導される４価の芳香族基、Ｒ_１は脂肪族ジアミンから誘導される２価のジアミン残基、Ｒ_２は芳香族ジアミンから誘導される２価のジアミン残基をそれぞれ表し、Ａｒ及び／又はＲ_２中にはケトン基を含み、ｍ、ｎは各構成単位の存在モル比を示し、ｍは０．５〜１．０の範囲内、ｎは０〜０．５の範囲内である］

[In the formula, Ar is a tetravalent aromatic group derived from an acid anhydride including an aromatic tetracarboxylic acid anhydride, R ₁ is a divalent diamine residue derived from an aliphatic diamine, and R ₂ is an aromatic group. Each represents a divalent diamine residue derived from a group diamine, Ar and / or R ₂ contains a ketone group, m and n represent the molar ratio of each constituent unit, and m is from 0.5 to Within the range of 1.0, n is within the range of 0 to 0.5]

In the polyimide resin having the structural units represented by the above general formulas (1) and (2), one or both of the group Ar and the group R ₂ , preferably a group Ar, contains a ketone group, Involves in crosslinking reaction with compounds. That is, the C = N bond is formed by reacting the ketone group in the group Ar and / or the group R ₂ with an amino compound having at least two primary amino groups of the component (B) as functional groups. Thus, the polyimide resin is cross-linked by the amino compound.

  In the structural units represented by the general formulas (1) and (2), preferred aromatic tetracarboxylic acid anhydrides for forming a group Ar containing a ketone group are, for example, represented by the following formula (3): Mention may be made of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA).

  Moreover, in the structural units represented by the general formulas (1) and (2), as the aromatic tetracarboxylic acid anhydride as a raw material for forming the group Ar, in addition to those having the ketone group, for example, 4,4′-oxydiphthalic anhydride (ODPA, also known as 5,5′-oxybis-1,3-isobenzofurandione), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), pyromellitic dianhydride (PMDA), and the like can be used. These can be used alone or in combination of two or more.

In the structural unit represented by the general formula (1), as a raw material for forming the group R ₁ (a divalent diamine residue derived from an aliphatic diamine), an aliphatic diamine having a cyclic structure in the molecule An aliphatic diamine having a carbon number in the range of 24 to 48 or an aliphatic diamine derived from a dimer acid is preferable, and a aliphatic diamine having a carbon number in the range of 24 to 48 is more preferable. Is good. Here, the cyclic structure means an aliphatic cyclic structure other than the aromatic ring, and may have an unsaturated bond in the ring. In addition, if the aliphatic diamine has less than 24 carbon atoms, the solubility may be lowered and handling may be difficult, and if the carbon number exceeds 48, crosslinking due to imine bonds between polyimide resins may not be formed. By selecting an aliphatic diamine as described above, flexibility can be imparted to the polyimide resin, and an imine bond can be effectively formed, so that a decrease in adhesive force is not caused even in use in a high temperature environment. be able to.

The aliphatic diamine derived from the dimer acid preferably used as a raw material for forming a divalent diamine residue derived from the aliphatic diamine of the group R ₁ is obtained by converting the carboxyl group of the dimer acid into a hydroxyl group. Later, it is an aliphatic diamine converted to an amino group. That is, an aliphatic diamine derived from dimer acid can be obtained by polymerizing an unsaturated fatty acid such as oleic acid or linoleic acid to form dimer acid, reducing it, and then aminating. As such an aliphatic diamine, for example, a commercial product such as DDA (aliphatic diamine having 36 carbon atoms, manufactured by Croda Japan Co., Ltd., trade name: PRIAMINE 1074) can be used.

Moreover, in the structural unit represented by the general formula (2), as a diamine compound having a ketone group that can be used to form a group R ₂ (a divalent diamine residue derived from an aromatic diamine), for example, Aromatic diamines such as 4,4′-bis (3-aminophenoxy) benzophenone (BABP) and 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene (BABB) can be exemplified. Furthermore, in the structural unit represented by the general formula (2), as another aromatic diamine which is a raw material for forming the group R ₂ , for example, 2,2-bis (4-aminophenoxyphenyl) propane ( BAPP), 2,2′-divinyl-4,4′-diaminobiphenyl (VAB), 2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB), 2,2′-diethyl-4, 4′-diaminobiphenyl, 2,2 ′, 6,6′-tetramethyl-4,4′-diaminobiphenyl, 2,2′-diphenyl-4,4′-diaminobiphenyl, 9,9-bis (4- And aminophenyl) fluorene. These aromatic diamines can be used alone or in combination of two or more.

  As represented by the general formulas (1) and (2), in the present invention, an aliphatic diamine and an aromatic diamine can be used in combination as the diamine component, but the crosslinked polyimide resin is used in a high temperature environment. From the viewpoint of imparting sufficient adhesive strength, it is preferable that the molar ratio [m / (m + n)] of the aliphatic diamine in the total diamine component is within a range of, for example, 0.5 to 1.0. More preferably, it is within the range of 8 to 1.0, and most preferably 1.0.

[Synthesis of polyimide resin]
The polyimide resin having a ketone group as the component (A) is prepared by reacting the aromatic tetracarboxylic acid anhydride, an aliphatic diamine and an aromatic diamine (if necessary) in a solvent to obtain a polyamic acid which is a precursor resin. It can be produced by heating and ring closure after formation. 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 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 in which heating is performed in the solvent at a temperature within the range of 80 to 300 ° C. for 1 to 24 hours is suitably employed.

Moreover, the polyimide resin which has the ketone group of the said (A) component becomes an imide structure obtained by reaction with aromatic tetracarboxylic acid anhydride, aliphatic diamine, and aromatic diamine (when needed). For example, when used as an adhesive for a coverlay film, a completely imidized structure is most preferable in order to suppress copper diffusion. However, a part of the polyimide may be amic acid. The imidation ratio was measured at about 1015 cm ⁻¹ by measuring the infrared absorption spectrum of the polyimide thin film by a single reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: FT / IR620 manufactured by JASCO Corporation). Based on the absorbance of C═O stretching derived from an imide group of 1780 cm ⁻¹ , based on the benzene ring absorber.

[Amino compound]
Examples of the amino compound having at least two primary amino groups of the component (B) as functional groups include (I) dihydrazide compound, (II) aromatic diamine, and (III) aliphatic amine. it can.

(I) Dihydrazide compound:
Examples of the dihydrazide compound include those represented by the following general formula (4).

In the general formula (4), groups R ₃ may be, for example, a single bond, an aliphatic group, an aromatic group. What is preferable as R ₃ will be described with reference to the dihydrazide compound. For example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide dihydrazide, maleic acid dihydrazide Diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthodioic acid dihydrazide, 4,4-bisbenzene dihydrazide, 1,4-naphthoic acid dihydrazide, 2,6-pyridinediacid dihydrazide, itaconic acid dihydrazide and the like can be mentioned. The above dihydrazide compounds may be used alone or in combination of two or more.

(II) Aromatic diamine:
Examples of the aromatic diamine include 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 ′ Preferred examples include -diaminobiphenyl, 4,4'-diaminobenzanilide, bisaniline fluorene and the like. Further, other examples of the aromatic diamine include 2,2-bis- [4- (3-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3 -Aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-aminophenoxy)] biphenyl, bis [1- (3-Aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] ether Bis [4- (3-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′-diaminodiphenyl Tan, 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 ′ -Dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4 "-diamino-p-terphenyl, 3,3" -diamino-p-terphenyl, m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 1,4-bis (4-aminopheno) B) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4 ′-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] bisaniline, bis (p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p- Bis (2-methyl-4-aminopentyl) benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis ( β-amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, - xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, it can be mentioned piperazine. The above aromatic diamines may be used alone or in combination of two or more.

(III) Aliphatic amines:
Examples of the aliphatic amine include 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 2-methyl-1,5-diaminopentane, 1,7-diaminoheptane, and 1,8. -Diaminooctane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12- Diaminoalkanes such as diaminododecane, 4,4′-methylenebiscyclohexylamine, tris (2-aminoethyl) amine, N, N′-bis (2-aminoethyl) -1,3-propanediamine, bis (3 -Aminopropyl) ethylenediamine, 1,4-bis (3-aminopropyl) piperazine, diethylenetriamine, N-methyl-2,2'-dia Nodiethylamine, 3,3′-diaminodipropylamine, amines containing nitrogen atoms such as N, N-bis (3-aminopropyl) methylamine, bis (3-aminopropyl) ether, 1,2-bis Amines containing oxygen atoms such as (2-aminoethoxy) ethane, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5.5] -undecane, Examples include amines having a sulfur atom such as 2'-thiobis (ethylamine). These aliphatic amines may be used alone or in combination of two or more.

  Of the amino compounds having at least two primary amino groups as functional groups, such as (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines, dihydrazide compounds are most preferable. When the dihydrazide compound is used, the curing time of the adhesive resin composition can be shortened as compared with the case where another amino compound is used. This is because the product obtained by reacting the primary amino group of the dihydrazide compound with the ketone group has a semicarbazone-like molecular structure, and forms a dimer structure by hydrogen bonding between NHs between molecules. Because the stability of the product is improved, the equilibrium of the reaction is biased toward the product side, and the reverse reaction in the direction of generating the ketone group of the polyimide resin as the raw material and the amino group of the dihydrazide compound is less likely to occur. It is considered a thing.

  In addition, amino compounds such as (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines are, for example, combinations of (I) and (II), combinations of (I) and (III), It can also be used in combination of two or more types across categories, such as a combination of (I), (II) and (III).

  In addition, from the viewpoint of making the network structure formed by crosslinking with the amino compound of the component (B) more dense, the amino compound of the component (B) has a molecular weight (weight average molecular weight when the amino compound is an oligomer). ) Is preferably 5,000 or less, more preferably 90 to 2,000, still more preferably 100 to 1,500. Among these, amino compounds having a molecular weight of 100 to 1,000 are particularly preferable. When the molecular weight of the amino compound is less than 90, one amino group of the amino compound only forms a C = N bond with the ketone group of the polyimide resin, and the remaining amino group is sterically bulky and remains. This amino group tends to hardly form a C═N bond.

[Production of crosslinked polyimide resin (cured product)]
The cross-linked polyimide resin is obtained by adding an amino compound having at least two primary amino groups as a functional group (B) to a resin solution containing a polyimide resin having a ketone group (A). It is produced by a condensation reaction of the ketone group of and the primary amino group of the amino compound. By this condensation reaction, the resin solution (adhesive resin composition) is cured to become a cured product. In this case, the added amount of the amino compound is 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, more preferably 0.001 mol to 1.2 mol in total for the primary amino group per mol of the ketone group An amino compound can be added so that it may become 0.03 mol-0.9 mol, Most preferably, it is 0.04 mol-0.5 mol. Adhesive containing polyimide resin because the addition of amino compound such that the total amount of primary amino groups is less than 0.004 mol per 1 mol of ketone groups is not sufficient for crosslinking of polyimide resin with amino compounds. Solder heat resistance tends to be difficult to develop in the cured product after curing the resin composition, and when the added amount of the amino compound exceeds 1.5 mol, the unreacted amino compound acts as a thermoplastic agent and is cured. There is a tendency that the solder heat resistance is lowered in the object, and the long-term heat resistance at high temperature is lowered.

In addition, the condensation reaction conditions are such that the ketone group in the (A) component polyimide resin and the primary amino group of the amino compound in the (B) component react to form an imine bond (C = N bond). There is no particular restriction. Depending on the type of amino compound, for example, when an aliphatic amine is used as the amino compound of component (B), it can be condensed with the ketone group in the polyimide resin even at room temperature. It is preferable to promote. (B) When using an aliphatic amine as an amino compound of component, it is preferable to perform heat condensation within the range of 60-200 degreeC, for example, When using an aromatic amine, it is the range of 120-220 degreeC, for example. It is preferable to perform heat condensation in the inside. The temperature of the heat condensation is, for example, 120 for the purpose of releasing water generated by the condensation out of the system or simplifying the condensation step when the heat condensation reaction is subsequently performed after the synthesis of the polyimide resin. Within the range of -220 degreeC is preferable, and the inside of the range of 140-200 degreeC is more preferable. The reaction time is preferably about 1 to 24 hours, and the end point of the reaction is 1670 cm by measuring the infrared absorption spectrum using, for example, a Fourier transform infrared spectrophotometer (commercially available product: FT / IR620 manufactured by JASCO Corporation). ^-1 reduction of the absorption peak derived from the ketone group in the polyimide resin in the vicinity of or loss, and can be confirmed by the appearance of the absorption peak derived from the imine group 1635cm around ^-1.

Heat condensation of the ketone group of the polyimide resin as the component (A) and the primary amino group of the amino compound as the component (B) is, for example,
(A) Following the synthesis (imidization) of the polyimide resin, adding an amino compound and heating,
(B) charging an excess amount of an amino compound as a diamine component in advance, and heating the polyimide resin together with the remaining amino compound not involved in imidization (or amidation) following the synthesis (imidization) of the polyimide resin; Or
(C) heating after processing the composition of the polyimide resin to which the amino compound has been added into a predetermined shape (for example, after being applied to an arbitrary base material or after being formed into a film),
Etc.

  In the case of (b) above, the excess amino compound is consumed in the reaction of sealing the acid anhydride group as a terminal substituent during the production of the polyimide resin, and the molecular weight of the resulting polyimide resin may be extremely reduced. Therefore, it tends to be difficult to obtain sufficient heat resistance in the cured product. Therefore, when an excess amount of an amino compound is charged in advance [the above (b)], it is preferably used as long as the effects of the present invention are not impaired. In order to effectively react at least two primary amino groups in an amino compound with a ketone group to form a C═N bond, the amino compound is synthesized from a polyimide resin as described in (a) or (c) above. It is preferable to add after completing (imidization). In the case of (c) above, the heat condensation is performed by, for example, the heat of heat treatment performed when the adhesive layer of the coverlay film is formed from a composition in which an amino compound and a polyimide resin are mixed, or the adhesive layer is formed. After that, it can also be performed by using heat at the time of thermocompression bonding to the circuit board having the wiring layer.

[Inorganic filler]
The cross-linked polyimide resin can contain a plate-like inorganic filler having an average particle diameter in the range of 2 to 25 μm as an arbitrary component (C). (C) When the inorganic filler of component (C) is blended, when the cross-linked polyimide resin is used for an adhesive layer of a coverlay film, for example, the permeation of oxygen in the atmosphere is blocked by the inorganic filler having gas barrier properties. The oxidation of copper wiring and the diffusion of copper are suppressed, and long-term heat resistance can be improved.

  As the inorganic filler of component (C), it is preferable to use a plate-like material in order to impart sufficient gas barrier properties to the adhesive layer. Here, the “plate shape” is used to mean, for example, a flat shape, a flat plate shape, a flake shape, a scale shape, etc., and the thickness of the inorganic filler is sufficiently smaller than the major axis or minor axis of the plane portion (preferably 1/2 or less). In particular, it is preferable to use a scale-like inorganic filler. From another viewpoint, “plate-like” means that the ratio of the major axis to the thickness (major axis / thickness) of the filler particles is preferably 5 or more, more preferably 10 or more, and still more preferably 15 or more. In the plate-like inorganic filler, the relationship between the long diameter and the average particle diameter is preferably long diameter ≧ average particle diameter> 0.4 × long diameter, more preferably long diameter ≧ average particle diameter ≧ 0.5 ×. It is good that it is a long diameter. In the present invention, the major axis (or minor axis) and thickness of the filler particles, and the ratio of the major axis to the thickness are the average values when ten arbitrary fillers are measured with a stereomicroscope. If the shape of the inorganic filler is not plate-like, for example, it is spherical, the gas barrier property of the adhesive layer is lowered, the oxidation of the wiring layer proceeds, and the adhesive strength of the coverlay film may be reduced. It does not preclude blending inorganic fillers having a shape other than the plate shape as long as the effect of blending the plate filler is not impaired.

  As the inorganic filler of component (C), it is preferable to use an insulating inorganic filler such as talc, mica, sericite, clay, and kaolin.

  The inorganic filler preferably has an average particle size calculated by a laser diffraction method in the range of 2 to 25 μm, and more preferably in the range of 5 to 20 μm. Here, the particle size of the inorganic filler is based on the average value of the longitudinal diameters of the particles. When the average particle diameter exceeds the upper limit, the surface roughness of the adhesive layer of the coverlay film tends to occur. When the average particle diameter is less than the lower limit, it is difficult to obtain the effect of suppressing oxygen transmission.

  In addition, the particle size distribution of the inorganic filler is preferably 60% or more, more preferably 65% or more, and preferably the particle size of 20 μm or more is 10% or less on a number basis. When the inorganic filler having a particle diameter of 10 μm or less is less than 60%, when the adhesive resin composition is formed into a film, the fillers are arranged in layers, and protrusions appear on the film surface, which causes the film surface to become rough. In addition, if the inorganic filler having a particle size of 20 μm or more exceeds 10%, protrusions appear on the film surface, causing the surface of the film to become rough. For example, when a thin film of 15 μm or less is produced, the surface tends to be rough. Cheap. Moreover, 0.1-100 micrometers is preferable and, as for the frequency distribution of the particle size of an inorganic filler, 0.5-70 micrometers is more preferable. If the frequency distribution exceeds the upper limit, the surface of the adhesive layer tends to be rough, and if the frequency distribution is lower than the lower limit, it is difficult to obtain the effect of suppressing oxygen transmission.

  (C) The compounding quantity of the inorganic filler of a component is 5-200 weight part with respect to a total of 100 weight part of the said (A) component and (B) component, Preferably it is 10-150 weight part, Furthermore, Preferably it is 30-100 weight part, It is 40-80 weight part desirably. When the blending amount of the inorganic filler is less than 5 parts by weight with respect to 100 parts by weight of the total of the component (A) and the component (B), the blending effect cannot be obtained, and the effect of suppressing oxygen permeation cannot be obtained. Moreover, when the compounding quantity of an inorganic filler exceeds 200 weight part with respect to a total of 100 weight part of said (A) component and (B) component, an adhesive bond layer will become weak, As a result, cohesive failure in an adhesive bond layer As a result, the apparent adhesiveness is significantly reduced. In the present invention, a plate-like inorganic filler is used, but it is also possible to use a non-plate-like inorganic filler in combination. When the inorganic filler that is not plate-shaped is used in combination, the total amount of the inorganic filler (plate-shaped and other shapes total) exceeds 200 parts by weight with respect to 100 parts by weight of the total of component (A) and component (B). It is preferable not to do so.

[Action]
In the crosslinked polyimide resin, the reaction between the ketone group of the polyimide resin (A) and the primary amino group of the amino compound (B) is a dehydration condensation reaction. That is, as a result of the carbon atom of the ketone group in the polyimide resin and the nitrogen atom of the primary amino group forming a C = N bond, the chain polyimide resin is cross-linked by the amino compound to form a network polymer. It is considered a thing. Polyimide resin is difficult to cause intermolecular interaction, so it is difficult to control the orientation of the polyimide resin. However, when such a cross-linked structure occurs, not only the apparent high molecular weight of the polyimide resin but also the polyimide resin molecules It is considered that the heat resistance of the polyimide resin is improved and extremely excellent solder heat resistance can be obtained. Moreover, the nitrogen atom vicinity in C = N bond becomes three-dimensionally bulky, thereby reducing the nucleophilic ability of the copper atom of the polar group contained in the polyimide resin, thereby reducing the copper adhesive layer from the copper wiring. It is considered that diffusion can be suppressed and an effect of suppressing a decrease in adhesive strength in use in a high temperature environment can be obtained. For these reasons, the amino compound needs to have at least two amino groups, and the number of amino groups is preferably 2 to 5, more preferably 2 to 3. In addition, in an amino compound having three or more amino groups, the cross-linked structure after the two amino groups form a C═N bond becomes three-dimensionally bulky, so that the remaining unreacted amino group is a ketone group. It is particularly preferable that the number of amino groups is 2. Furthermore, from the viewpoint of shortening the curing time of the adhesive resin composition as described above, it is most preferable to use a dihydrazide compound as the amino compound.

  In addition, the crosslinked polyimide resin uses an aliphatic diamine, preferably dimer diamine, as a raw material for synthesizing the polyimide resin, so that flexibility or heat equal to or higher than that of the polyimide resin having a siloxane structure can be obtained without using siloxane diamine. It is possible to obtain characteristics such as adhesion durability to the surface. For this reason, it is possible to form a siloxane-free adhesive layer free from volatilization of cyclic siloxane that adversely affects electronic components. In the present invention, it is preferable not to use a siloxane diamine having a siloxane structure as the diamine component, but the use thereof is not completely excluded. For example, siloxane diamine may be used in combination with aliphatic diamine as a diamine component as long as it can be suppressed to a very small amount of volatilization that does not adversely affect electronic components.

[Adhesive resin composition]
The adhesive resin composition contains a polyimide resin having a ketone group [component (A)] and an amino compound having at least two primary amino groups as functional groups [component (B)] as essential components. To do. This adhesive resin composition is obtained by mixing or kneading the component (A) and the component (B) and / or heating in a state containing the component (A) and the component (B). And the primary amino group of the amino compound undergo a condensation reaction to form a C═N bond. That is, it changes into the crosslinked polyimide resin which is a hardened | cured material by the condensation reaction of a polyimide resin and an amino compound. In the adhesive resin composition, the weight average molecular weight of the component (A) is preferably 10,000 to 200,000, and more preferably 20,000 to 150,000. When the weight average molecular weight of the component (A) is less than 10,000, it becomes difficult to control the fluidity when the adhesive resin composition is made into a solution, and the heat resistance of the cured product tends to decrease. . On the other hand, when the weight average molecular weight exceeds 200,000, the solubility in the solvent tends to be impaired.

  The adhesive resin composition has a total of primary amino groups of 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, more preferably 0.03 mol per mol of ketone groups. An amino compound can be contained so as to have a molar amount of 0.9 to 0.9 mol, particularly preferably 0.04 mol to 0.5 mol.

  In addition to the polyimide resin as the component (A) and the amino compound as the component (B), the adhesive resin composition preferably contains the inorganic filler as the component (C) as an optional component. Furthermore, if necessary, other resin components such as a plasticizer and an epoxy resin, a curing accelerator, a coupling agent, a filler, a pigment, a solvent, a flame retardant, and the like can be appropriately blended as other optional components. However, some plasticizers contain a large number of polar groups, and there is a concern that this may promote the diffusion of copper from the copper wiring. Therefore, it is preferable not to use the plasticizer as much as possible.

  When blending an optional component other than the component (C) in the adhesive resin composition, for example, with respect to 100 parts by weight of the polyimide resin of the component (A), the total amount of the optional components is 1 to 50 parts by weight. It is preferable that the amount is 2 to 7 parts by weight.

  The adhesive resin composition obtained as described above has excellent flexibility and thermoplasticity when an adhesive layer is formed using the adhesive resin composition. For example, a wiring portion such as an FPC or a rigid flex circuit board. It has preferable characteristics as an adhesive for a coverlay film that protects the film. When used as an adhesive layer of a coverlay film, the adhesive resin composition is applied in a solution state (for example, a varnish containing a solvent) to one side of the coverlay film material, and then, for example, 60 to 220 ° C. A coverlay film having a coverlay film material layer and an adhesive layer can be formed by thermocompression bonding at a temperature. In this case, using the heat at the time of thermocompression bonding, the ketone group of the (A) component polyimide resin and the primary amino group of the (B) component amino compound can be heated and condensed. Moreover, even when heat condensation at the time of thermocompression bonding is not sufficient, heat treatment can be further performed after thermocompression bonding for heat condensation. When heat treatment is performed after thermocompression bonding, the heat treatment temperature is preferably, for example, 60 to 220 ° C, and more preferably 80 to 200 ° C. Further, the adhesive resin composition is applied on an arbitrary substrate in a solution state (for example, a varnish containing a solvent), dried at a temperature of, for example, 80 to 180 ° C., and then peeled to adhere. A cover lay film having a cover lay film material layer and an adhesive layer can also be formed by thermocompression bonding the adhesive film with the cover lay film material at a temperature of, for example, 60 to 220 ° C. Can be formed. Also in this case, the ketone group of the polyimide resin as the component (A) and the primary amino group of the amino compound as the component (B) can be heat-condensed by using heat during thermocompression bonding. As described above, the adhesive resin composition is processed into various forms with the ketone group of the polyimide resin (A) and the primary amino group of the amino compound (B) unreacted. Available. Furthermore, the adhesive resin composition can be used by forming a coating film in a solution state by screen printing on an arbitrary substrate and drying it at a temperature of 80 to 180 ° C., for example. Preferably, a cured product can be formed by further heat-treating at a temperature of 130 to 220 ° C. for a predetermined time to completely cure the coating film.

[Coverlay film / bonding sheet]
The cover lay film includes a cover lay film material and an adhesive layer composed of the adhesive resin composition laminated on the cover lay film material. The coverlay film material in the coverlay film is not intended to be limited, but includes, for example, polyimide resin films such as polyimide resin, polyetherimide resin, and polyamideimide resin, polyamide resin film, and polyester resin film. Can be used. Among these, it is preferable to use a polyimide resin film having excellent heat resistance. 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 10 μm or more and 50 μm or less, for example.

  Moreover, what formed the adhesive resin composition in the film form can be utilized also as a bonding sheet | seat of multilayer FPC, for example. When used as a bonding sheet, the adhesive resin composition is applied as a solution on an arbitrary substrate film, dried at a temperature of, for example, 80 to 180 ° C., and then peeled off to bond the adhesive film as it is. You may use as a sheet | seat and may use this adhesive film in the state laminated | stacked with arbitrary base film. When used as a bonding sheet, the heat of thermocompression bonding can be used to heat-condense the ketone group of the polyimide resin and the primary amino group of the amino compound, and further heat treatment can be applied after thermocompression bonding. Heat condensation can also be performed.

  Moreover, a coverlay film and a bonding sheet are good also as a form which has a release material layer by bonding a release material on the adhesive surface. The material of the release material is not particularly limited as long as it can be peeled without impairing the form of the coverlay film or the bonding sheet. For example, resin films such as polyethylene terephthalate, polyethylene, and polypropylene, and these resin films And the like laminated on paper can be used.

[Circuit board]
As long as the circuit board includes the coverlay film and the bonding sheet obtained as described above, the configuration is not particularly limited. For example, a preferred form of the circuit board includes at least a base material, a wiring layer made of a metal such as copper formed on the base material in a predetermined pattern, and a coverlay film that covers the wiring layer. The base material of the circuit board is not particularly limited, but in the case of FPC, the same material as the coverlay film material is preferably used, and the base material made of polyimide resin is preferably used.

  By using a coverlay film for the circuit board, an adhesive layer having excellent flexibility and thermoplasticity is filled between the wirings, and high adhesion between the coverlay film and the wiring layer is obtained.

  The circuit board may be configured as a multilayer circuit board. In this case, an adhesive film obtained from the adhesive resin composition can be used not only for the coverlay film but also for the bonding sheet.

  The production of the circuit board is not particularly limited. For example, after the metal foil of a metal-clad laminate such as a copper-clad laminate is processed into a predetermined pattern by a method such as chemical etching, it is necessary on the circuit. For example, a cover lay film may be laminated on such a portion and, for example, thermocompression bonding may be performed using a hot press apparatus. In this case, the pressure bonding conditions are not particularly limited. For example, the pressure bonding temperature is preferably 130 ° C. or higher and 220 ° C. or lower, more preferably 140 ° C. or higher and 200 ° C. or lower, and the pressure is 0.1 MPa or higher and 4 MPa or lower. It is preferable. In the state of the coverlay film, when the ketone group of the (A) component polyimide resin and the primary amino group of the (B) component amino compound are unreacted, the coverlay film is heated to the circuit wiring. The condensation reaction can be caused by using heat at the time of pressure bonding. That is, the adhesive layer of the cover lay film is disposed so as to abut the wiring layer, and simultaneously with the step of thermocompression bonding both members, the ketone group of the (A) component polyimide resin contained in the adhesive layer and (B It is possible to form a C═N bond by condensation reaction with the primary amino group of the component amino compound.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of adhesive strength]
The adhesive strength of the test piece cut out to a width of 10 mm and a length of 100 mm was placed on a glossy surface of copper foil (thickness of 35 μm) (with rust-proof metal removed), temperature 170 ° C., pressure 1 MPa, Press for 1 minute in time, and then heat in oven at 150 ° C. for 6 hours (however, in Reference Example 7, press at 170 ° C., pressure 1 MPa for 1 minute, and then When heated in an oven at a temperature of 150 ° C. for 24 hours, and then peeled off at a rate of 50 mm / min in the 180 ° direction using a tensile tester (Toyo Seiki Co., Ltd., Strograph-M1) This force is the adhesive strength.

[Measurement of weight average molecular weight (Mw)]
The weight average molecular weight was measured by a gel permeation chromatograph (manufactured by Tosoh Corporation, using HLC-8220GPC). Polystyrene was used as a standard substance, and tetrahydrofuran was used as a developing solvent.

[Evaluation method of warpage]
The warpage was evaluated by the following method. A polyimide adhesive was applied onto a 25 μm thick Kapton film so that the thickness after drying was 35 μm. In this state, the Kapton film was placed on the lower surface, and the average of the heights of warping at the four corners of the film was measured.

The abbreviations used in the examples represent the following compounds.
BTDA: 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride BPDA: 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride ODPA: 4,4′-oxydiphthalic anhydride ( Also known as 5,5'-oxybis-1,3-isobenzofurandion)
BAPP: 2,2-bis (4-aminophenoxyphenyl) propane BAFL: bisaniline fluorene DDA: C36 aliphatic diamine (trade name: PRIAMINE 1074, amine value: 205 mgKOH / g, cyclic structure And a mixture of dimer diamines having a chain structure, content of dimer component; 95% by weight or more)
N-12: dodecanedioic acid dihydrazide ADH: adipic acid dihydrazide K-1: talc (manufactured by Nippon Talc Co., Ltd., trade name; MICRO ACE K-1, shape: scaly, average major axis; 7.0 μm, average minor axis; 5.8 μm, ratio of major axis to thickness: 15 or more, average particle size: 6.6 μm, median diameter (D50); 6.9 μm, maximum particle size; 64.9 μm, minimum particle size: 0.5 μm, mode Diameter: 8.7 μm, cumulative particle amount of particle size of 10 μm or less; 77%, cumulative particle amount of particle size of 20 μm or more; 5%)

Example 1
A 3000 ml separable flask was charged with 111.96 g BTDA (0.347 mol), 188.04 g DDA (0.347 mol), 420 g N-methyl-2-pyrrolidone and 280 g xylene. Mix well at 1 ° C. for 1 hour to obtain a polyamic acid solution. The polyamic acid solution was heated to 190 ° C., heated and stirred for 4 hours, and 80 g of N-methyl-2-pyrrolidone and 200 g of xylene were added to obtain a polyimide solution a in which imidization was completed. The obtained polyimide solution a had a solid content of 29.5% by weight, and the weight average molecular weight (Mw) of the polyimide resin was 75,700.

Example 2
A 3000 ml separable flask was charged with 105.66 g BPDA (0.359 mol), 194.34 g DDA (0.359 mol), 420 g N-methyl-2-pyrrolidone and 280 g xylene. Mix well at 1 ° C. for 1 hour to obtain a polyamic acid solution. The polyamic acid solution was heated to 190 ° C., heated and stirred for 4 hours, and 80 g of N-methyl-2-pyrrolidone and 200 g of xylene were added to obtain a polyimide solution b in which imidization was completed. The obtained polyimide solution b had a solid content of 29.5% by weight, and the weight average molecular weight (Mw) of the polyimide resin was 60,100.

Example 3
In a 3000 ml separable flask, 63.51 g BTDA (0.197 mol), 61.14 g ODPA (0.197 mol), 106.66 g DDA (0.197 mol), 68.67 g BAFL (0 197 mol), 420 g of N-methyl-2-pyrrolidone and 280 g of xylene were charged and mixed well at 40 ° C. for 1 hour to obtain a polyamic acid solution. The polyamic acid solution was heated to 190 ° C., heated and stirred for 4 hours, and 80 g of N-methyl-2-pyrrolidone and 200 g of xylene were added to obtain a polyimide solution c in which imidization was completed. The resulting polyimide solution c had a solid content of 29.5% by weight, and the weight average molecular weight (Mw) of the polyimide resin was 68,600.

  Examples 1 to 3 are summarized in Table 1.

[Reference Example 1]
169.49 g of polyimide solution a obtained in Example 1 (50 g as solid content) was blended with 3.5 g of N-12 (0.014 mol) and 25 g of K-1 to prepare 20.07 g of N- Methyl-2-pyrrolidone was added for dilution, and the mixture was further stirred for 1 hour to obtain polyimide solution 1.

The obtained polyimide solution 1 was applied to one side of a polyimide film (manufactured by DuPont, trade name: Kapton ENS, length × width × thickness = 200 mm × 300 mm × 25 μm), dried at 80 ° C. for 15 minutes, and adhesive A coverlay film 1 having a layer thickness of 25 μm was obtained. This cover lay film 1 is placed on a copper foil from which the anticorrosive metal layer has been removed, pressed at a temperature of 170 ° C., a pressure of 1 MPa, and a time of 1 minute, and then in an oven at a temperature of 150 ° C. and a time of 6 hours. And an evaluation sample 1 was obtained. The adhesive strength with the copper foil after curing was 1.5 kN / m. Moreover, the warp of the coverlay film was no problem. When the infrared absorption spectrum of the adhesive layer in the evaluation sample 1 was measured using a Fourier transform infrared spectrophotometer (commercially available product: FT / IR620 manufactured by JASCO Corporation), the absorption of the ketone group derived from BTDA was observed in the vicinity of 1673 cm ^−1. It was confirmed that it decreased, and absorption of an imine group was further confirmed in the vicinity of 1635 cm ⁻¹ .

  Further, a printed circuit board having a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} formed of copper on both sides of the polyimide film is prepared, and the coverlay film 1 obtained in Reference Example 1 is used as the printed circuit board. Placed on the circuit surface, pressed at a temperature of 170 ° C., a pressure of 1 MPa, and a time of 1 minute, and then heated in an oven at a temperature of 150 ° C. and a time of 6 hours to obtain a wiring board 1 provided with a coverlay film. It was.

[Reference Example 2]
Instead of blending 25 g of K-1 in Reference Example 1, a polyimide solution 2 was obtained in the same manner as in Reference Example 1 except that K-1 was not blended, and then the coverlay film 2 was An evaluation sample 2 was obtained. The adhesive strength with the copper foil after curing was 1.8 kN / m. Moreover, the warp of the coverlay film was no problem.

  Further, in the same manner as in Reference Example 1, a printed circuit board on which a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is prepared, and the coverlay film 2 obtained in Reference Example 2 is printed. It was placed on the circuit surface of the substrate and thermocompression bonded to obtain a wiring substrate 2 provided with a coverlay film.

[Reference Example 3]
A polyimide solution 3 was prepared in the same manner as in Reference Example 1 except that 2.0 g of N-12 (0.008 mol) was blended instead of blending 3.5 g of N-12 in Reference Example 1. After that, a coverlay film 3 was obtained, and an evaluation sample 3 was obtained. The adhesive strength with the copper foil after curing was 1.4 kN / m. Moreover, the warp of the coverlay film was no problem.

  Further, in the same manner as in Reference Example 1, a printed circuit board on which a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is prepared, and the coverlay film 3 obtained in Reference Example 3 is printed. Placed on the circuit surface of the substrate and thermocompression bonded, a wiring substrate 3 provided with a coverlay film was obtained.

[Reference Example 4]
A polyimide solution 4 was prepared in the same manner as in Reference Example 1 except that 1.0 g of N-12 (0.004 mol) was blended instead of blending 3.5 g of N-12 in Reference Example 1. After that, a coverlay film 4 was obtained and an evaluation sample 4 was obtained. The adhesive strength with the copper foil after curing was 1.5 kN / m. Moreover, the warp of the coverlay film was no problem.

  Further, in the same manner as in Reference Example 1, a printed circuit board on which a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is prepared, and the coverlay film 4 obtained in Reference Example 4 is printed. Placed on the circuit surface of the substrate and thermocompression bonded, a wiring substrate 4 provided with a coverlay film was obtained.

[Reference Example 5]
A polyimide solution 5 was prepared in the same manner as in Reference Example 1 except that 5.0 g of N-12 (0.019 mol) was blended instead of blending 3.5 g of N-12 in Reference Example 1. After that, a coverlay film 5 was obtained, and an evaluation sample 5 was obtained. The adhesive strength with the copper foil after curing was 1.4 kN / m. Moreover, the warp of the coverlay film was no problem.

  Further, in the same manner as in Reference Example 1, a printed circuit board on which a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is prepared, and the coverlay film 5 obtained in Reference Example 5 is printed. Placed on the circuit surface of the substrate and thermocompression bonded, a wiring substrate 5 provided with a coverlay film was obtained.

[Reference Example 6]
Instead of using the polyimide resin c obtained in Example 3 instead of the polyimide resin a in Reference Example 1 and blending 3.5 g of N-12, 0.9 g of N-12 ( Except that 0.003 mol) was added, a polyimide solution 6 was obtained in the same manner as in Reference Example 1, and then a coverlay film 6 was obtained and an evaluation sample 6 was obtained. The adhesive strength with the copper foil after curing was 1.0 kN / m. Moreover, the warp of the coverlay film was no problem.

  Further, in the same manner as in Reference Example 1, a printed circuit board on which a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is prepared, and the coverlay film 6 obtained in Reference Example 6 is printed. Placed on the circuit surface of the substrate and thermocompression bonded, a wiring substrate 6 provided with a coverlay film was obtained.

[Reference Example 7]
A polyimide solution 7 was obtained in the same manner as in Reference Example 1 except that 5.0 g of BAPP (0.012 mol) was blended instead of blending 3.5 g of N-12 in Reference Example 1. It was. A coverlay film 7 was obtained. This coverlay film 7 is placed on a copper foil from which the rust-proof metal layer on the surface has been removed, pressed under conditions of a temperature of 170 ° C., a pressure of 1 MPa, and a time of 1 minute, and then in an oven at a temperature of 150 ° C. and a time of 24 hours. And an evaluation sample 7 was obtained. The adhesive strength with the copper foil after curing was 1.3 kN / m. Moreover, the warp of the coverlay film was no problem.

  Further, in the same manner as in Reference Example 1, a printed circuit board on which a circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is prepared, and the coverlay film 7 obtained in Reference Example 7 is printed. Placed on the circuit surface of the substrate and thermocompression bonded, a wiring substrate 7 provided with a coverlay film was obtained.

Reference Example 8
Instead of blending 3.5 g of N-12 in Reference Example 1, a polyimide solution was obtained in the same manner as in Reference Example 1 except that N-12 was not blended. And an evaluation sample was obtained. This evaluation sample was evaluated in the same manner as in Reference Example 1.

Reference Example 9
Instead of the polyimide solution a in Reference Example 1, the polyimide solution b obtained in Example 2 was used, and instead of blending 3.5 g of N-12, N-12 was not blended. Except for this, in the same manner as in Reference Example 1, after obtaining a polyimide solution, a coverlay film was obtained, and an evaluation sample was obtained. This evaluation sample was evaluated in the same manner as in Reference Example 1.

Reference Example 10
Instead of the polyimide solution a in Reference Example 1, the polyimide solution b obtained in Example 2 was used, except that a polyimide solution was obtained in the same manner as in Reference Example 1, and then a coverlay film was obtained and evaluated. A sample was obtained. This evaluation sample was evaluated in the same manner as in Reference Example 1.

  The results of Reference Examples 1 to 10 are summarized in Tables 2 and 3. In addition, the molar ratio in Table 2, Table 3 means the molar ratio of the sum total of the primary amino group in an amino compound with respect to 1 mol of ketone groups in a polyimide resin.

  From Tables 2 and 3, the coverlay films of Reference Examples 1 to 7 using the crosslinked polyimide resin obtained by the reaction of the polyimide resin as the component (A) and the amino compound as the component (B) as the adhesive Also, the adhesive strength with the copper foil was sufficient. Moreover, since the coverlay films of Reference Examples 1 to 7 did not contain a siloxane skeleton in the crosslinked polyimide resin, it was not necessary to consider the problem of volatilization of cyclic siloxane.

  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. For example, in the above-described embodiment, as an application of the crosslinked polyimide resin, a coverlay film of a circuit board such as an FPC or an adhesive for a bonding sheet has been described as an example. However, applications other than the above, for example, tape automated bonding (TAB) ), And can be used for forming an adhesive resin in a chip size package (CSP) or the like.

Claims (4)

A solvent-soluble polyimide resin having a weight average molecular weight in the range of 20,000 to 150,000,
It is obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride and a diamine component containing an aliphatic diamine, and does not contain a siloxane compound as a raw material,
A solvent-soluble polyimide resin for forming an adhesive for a coverlay film, comprising structural units represented by the following general formulas (1) and (2).

[In the formula, Ar is a tetravalent aromatic group derived from an acid anhydride including an aromatic tetracarboxylic acid anhydride, and R ₁ is an aliphatic group having a carbon number of 24 to 48 derived from dimer acid. Divalent diamine residue derived from diamine, R ₂ represents a divalent diamine residue derived from aromatic diamine, respectively, Ar and / or R ₂ contains a ketone group, m and n are The abundance ratio of each structural unit is shown, m is in the range of 0.5 to 1.0, and n is in the range of 0 to 0.5 . However, when Ar does not contain a ketone group, the case where m is 1.0 and n is 0 is excluded. ]   The aromatic diamine is 4,4′-bis (3-aminophenoxy) benzophenone, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 2,2-bis (4-aminophenoxyphenyl). Propane, 2,2′-divinyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-diethyl-4,4′-diaminobiphenyl, 2,2 The group consisting of ', 6,6'-tetramethyl-4,4'-diaminobiphenyl, 2,2'-diphenyl-4,4'-diaminobiphenyl, and 9,9-bis (4-aminophenyl) fluorene The solvent-soluble polyimide resin for forming an adhesive for a coverlay film according to claim 1, wherein the solvent-soluble polyimide resin is one or more selected from the group consisting of: The coverlay film according to claim 1 or 2, wherein the aromatic tetracarboxylic acid anhydride is 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride represented by the following formula (3). Solvent-soluble polyimide resin for forming adhesives.

From the group consisting of N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, xylene and toluene The solvent-soluble polyimide resin for forming an adhesive for a coverlay film according to any one of claims 1 to 3, which is soluble in one or more selected solvents.