JP7079227B2 - Method for manufacturing solvent-soluble polyimide resin - Google Patents

Description

The present invention relates to a method for producing 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 miniaturization, weight reduction, and space saving of electronic devices, a flexible printed wiring board (FPC) that is thin and lightweight, has flexibility, and has excellent durability even after repeated bending. The demand for Circuits) is increasing. Since FPC can be mounted three-dimensionally and at high density even in a limited space, it can be used for wiring of moving parts in electronic devices such as HDDs, DVDs, and mobile phones, and for parts such as cables and connectors. It is expanding.

A coverlay film is used for the FPC 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 the manufacture of FPC, a coverlay film material is attached to a circuit board via an adhesive layer by using a method such as hot pressing. The adhesive layer is required to have high adhesiveness to both circuit wiring patterns such as copper wiring and coverlay film materials. As an adhesive for such a coverlay film, it can be processed under heat pressure bonding conditions at a relatively low temperature, and it has excellent properties such as heat resistance. , Phthalate ester-based, phthalate ester-based, polyester-based and fatty acid ester-based adhesive resin compositions for printed substrates, which are blended with one or more plastic agents (for example, Patent Document 1). ).

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

Japanese Unexamined Patent Publication No. 10-212468 Japanese Unexamined Patent Publication No. 2006-117945

As mentioned in Patent Documents 1 and 2, the polyimide resin containing a siloxane skeleton has appropriate flexibility and adhesive durability against heat, and is therefore suitable for use as an adhesive for FPC coverlay films. There is. However, the polyimide resin containing a siloxane skeleton may contain a cyclic siloxane compound derived from a raw material, and the cyclic siloxane compound volatilizes when exposed to a high temperature environment for a long period of time and adheres to electrical contacts in electronic components. There is a concern that this may cause poor continuity. Therefore, it is desired to develop a polyimide resin adhesive that does not use a siloxane compound.

Furthermore, in-vehicle electronic devices that use FPCs that are installed in the engine room of automobiles are repeatedly placed in a high temperature environment of about 150 ° C. Therefore, the adhesive strength between the FPC coverlay film and wiring after long-term use. There is a problem that the wiring protection function is significantly reduced. With the expansion of FPC applications, it is expected that the number of situations where FPCs will be used not only in in-vehicle electronic devices but also in similarly harsh temperature environments will continue to increase. For this reason, in FPCs used in high temperature environments, it is strongly required to take measures against a decrease in the adhesive strength of the coverlay film.

Therefore, the subject of the present invention is that it is possible to form an adhesive layer that does not generate a volatile component composed of a cyclic siloxane compound and does not reduce the adhesive strength between the wiring layer and the coverlay film even in a usage environment that is repeatedly exposed to high temperatures. The present invention provides a method for producing a solvent-soluble polyimide resin.

In the method for producing a solvent-soluble polyimide resin of the present invention, a diamine component containing 50 mol% or more of an aliphatic diamine derived from dimer acid and an aromatic tetracarboxylic acid anhydride component are dissolved in an organic solvent. It is characterized by comprising a step of obtaining a polyimide precursor by stirring and polymerizing at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours.

The method for producing a solvent-soluble polyimide resin of the present invention further comprises a step of imidizing the precursor by heat treatment in which the precursor is heated in an organic solvent at a temperature condition in the range of 80 to 300 ° C. for 1 to 24 hours. You may. ..

In the method for producing a solvent-soluble polyimide resin of the present invention, the aromatic tetracarboxylic acid anhydride component may contain a benzophenone tetracarboxylic acid dianhydride. ..

In the method for producing a solvent-soluble polyimide resin of the present invention, the weight average molecular weight of the solvent-soluble polyimide resin may be in the range of 20,000 to 150,000.

In the method for producing a solvent-soluble polyimide resin of the present invention, the organic solvent is N, N-dimethylformaldehyde, N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, sulfuric acid. It may contain at least one selected from the group consisting of dimethyl, cyclohexanone, dioxane, tetrahydrofuran, diglyme and triglyme.

Since the method for producing a solvent-soluble polyimide resin of the present invention does not require a siloxane compound as a raw material, it is possible to prevent the generation of volatile components composed of cyclic siloxane, which adversely affect electronic components. Further, the resin film in which the adhesive layer is formed by using the solvent-soluble polyimide resin produced by the method of the present invention has excellent adhesion to the metal wiring layer, and this resin film is used for applications such as coverlay film. The reliability of circuit boards and electronic components can also be improved.

[Crosslinked polyimide resin]
The crosslinked polyimide resin is a crosslinked 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 with a diamine component containing an aliphatic diamine. The ketone group in this polyimide resin is derived from either one or both of the acid anhydride component and the diamine component. The polyimide resin has a structure in which the polyimide resin is crosslinked by the amino compound because the amino group of the component (B) reacts with the ketone group in the polyimide resin to form a C = N bond.

[(A) Polyimide resin having a ketone group]
Specific examples of the polyimide resin having a ketone group of the component (A) used in the crosslinked polyimide resin include a polyimide resin having a structural unit 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 containing an aromatic tetracarboxylic acid anhydride, R ₁ is a divalent diamine residue derived from an aliphatic diamine, and R ₂ is an aroma. Represents a divalent diamine residue derived from a group diamine, Ar and / or R ₂ contains a ketone group, m and n indicate the molar ratio of each constituent unit, and m is 0.5 to 0.5. 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 general formulas (1) and (2), one or both of the group Ar and the group _R2 , preferably the group Ar, contains a ketone group, and the ketone group is amino. Involved in the cross-linking reaction with the compound. That is, the ketone group in the group Ar and / or the group _R2 is reacted with an amino compound having at least two primary amino groups of the component (B) as a functional group to form a C = N bond. The polyimide resin is crosslinked by the amino compound.

In the structural unit represented by the general formulas (1) and (2), a preferable aromatic tetracarboxylic acid anhydride for forming a group Ar containing a ketone group is, for example, represented by the following formula (3). 3,3', 4,4'-benzophenone tetracarboxylic acid anhydride (BTDA) can be mentioned.

Further, in the structural units represented by the general formulas (1) and (2), the aromatic tetracarboxylic acid anhydride used as a raw material for forming the group Ar includes, for example, other than those having a ketone group. 4,4'-oxydiphthalic acid anhydride (ODPA, also known as; 5,5'-oxybis-1,3-isobenzofuranion), 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) 3,3', 4,4'-diphenylsulfone tetracarboxylic acid dianhydride (DSDA), pyromellitic acid 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 (divalent diamine residue derived from an aliphatic diamine), an aliphatic diamine having a cyclic structure in the molecule is used. , Aliphatic diamines in the range of 24-48 carbon atoms, or aliphatic diamines derived from dimer acid are preferable, and more preferably, aliphatic diamines derived from dimer acid in the range of 24-48 carbon atoms. 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. Further, if the carbon number of the aliphatic diamine is less than 24, the solubility may be lowered and handling may be difficult, and if the carbon number exceeds 48, cross-linking due to the imine bond between the polyimide resins may not be formed. By selecting the above-mentioned aliphatic diamine, the polyimide resin can be made flexible and an imine bond can be effectively formed, so that the adhesive strength does not decrease even when used in a high temperature environment. be able to.

The aliphatic diamine derived from the dimer acid, which is preferably used as a raw material for forming a divalent diamine residue derived from the aliphatic diamine of the group _R1 , is obtained by converting the carboxyl group of the dimer acid into a hydroxyl group. Later, it is an aliphatic diamine converted into an amino group. That is, the aliphatic diamine derived from dimer acid is obtained by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid to obtain dimer acid, reducing the amount, and then aminating the fatty acid. As such an aliphatic diamine, for example, a commercially available product such as DDA (aliphatic diamine having 36 carbon atoms, manufactured by Croda Japan Co., Ltd., trade name; PRIAMINE1074) can be used.

Further, as a diamine compound having a ketone group that can be used for forming a group _R2 (a divalent diamine residue derived from an aromatic diamine) in the structural unit represented by the general formula (2), for example. Aromatic diamines such as 4,4'-bis (3-aminophenoxy) benzophenone (BABP), 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene (BABB) can be mentioned. Further, in the structural unit represented by the general formula (2), as another aromatic diamine used as a raw material for forming the group _R2 , 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-) Aminophenyl) Fluolene and the like can be mentioned. 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, the molar ratio [m / (m + n)] of the aliphatic diamine in the total diamine component is preferably in the range of, for example, 0.5 to 1.0. It is more preferably in the range of 8 to 1.0, and most preferably 1.0.

[Synthesis of polyimide resin]
In the polyimide resin having the ketone group of the component (A), the aromatic tetracarboxylic acid anhydride, the aliphatic diamine and the aromatic diamine (if necessary) are reacted in a solvent to obtain a polyamic acid as a precursor resin. It can be manufactured by heating and closing the ring after it is produced. For example, the acid anhydride component and the diamine component are dissolved in an organic solvent in approximately equimolar 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. Polyamic acid is obtained. 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, dimethylshoxide, 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 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 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 300 ° C. for 1 to 24 hours is preferably adopted.

Further, the polyimide resin having the ketone group of the component (A) has an imide structure obtained by reaction with an aromatic tetracarboxylic acid anhydride, an aliphatic diamine and an aromatic diamine (if necessary). For example, when used as an adhesive for coverlay films, a completely imidized structure is most preferred in order to suppress the diffusion of copper. However, a part of the polyimide may be an amic acid. The imidization rate is around 1015 cm ^-1 by measuring the infrared absorption spectrum of the polyimide thin film by the single reflection ATR method using a Fourier transform infrared spectrophotometer (commercially available: FT / IR620 manufactured by Nippon Spectroscopy). It is calculated from the absorbance of C = O expansion and contraction derived from the imide group of 1780 cm ^-1 based on the benzene ring absorber of.

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

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

In the general formula (4), the group R ₃ may be, for example, a single bond, an aliphatic group, an aromatic group or the like. The following compounds will be described as examples of the preferred R3 by the example of the _dihydrazide compound. For example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutarate dihydrazide, adipic acid dihydrazide, pimelliate dihydrazide, suberic acid dihydrazide, azelaine acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, dodecanoic acid dihydrazide. , Diglycolic acid dihydrazide, tartrate dihydrazide, apple acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoenyl dihydrazide, 4,4-bisbenzenedihydrazide, 1,4-naphthoic acid dihydrazide, Examples thereof include 2,6-pyridinediacid dihydrazide and itaconic acid dihydrazide. 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, and 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, bisaniline fluorene and the like are preferably mentioned. Further, as other examples of aromatic diamines, 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'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 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-diaminopi Lysine, 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- Examples thereof include xylylene diamine, p-xylylene diamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine and the like. 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, 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'-diaminodiethylamine, 3,3'-diaminodipropylamine, N, N-bis (3) -Amines containing nitrogen atoms such as (aminopropyl) methylamine, bis (3-aminopropyl) ether, 1,2-bis (2-aminoethoxy) ethane, 3,9-bis (3-aminopropyl)- 2,4,8,10-Tetraoxaspiro [5.5] -amines containing oxygen atoms such as undecane, and amines having sulfur atoms such as 2,2'-thiobis (ethylamine) can be mentioned. can. The above aliphatic amines may be used alone or in combination of two or more.

Among the amino compounds having at least two primary amino groups as functional groups such as (I) dihydrazide compound, (II) aromatic diamine, and (III) aliphatic amine, the dihydrazide compound is 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 other amino compounds are 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 the 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 forming the ketone group of the raw material polyimide resin and the amino group of the dihydrazide compound is less likely to occur. It is considered to be a thing.

Further, the amino compounds such as (I) dihydrazide compound, (II) aromatic diamine, and (III) aliphatic amine are, for example, a combination of (I) and (II), a combination of (I) and (III), and the like. It is also possible to use two or more kinds in combination across categories, such as the combination of (I), (II) and (III).

Further, from the viewpoint of making the network structure formed by the cross-linking by the amino compound of the component (B) denser, the amino compound of the component (B) has a molecular weight thereof (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, an amino compound having a molecular weight of 100 to 1,000 is 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 remains because the periphery of the remaining amino groups becomes sterically bulky. Amino groups tend to be difficult to form C = N bonds.

[Manufacturing of crosslinked polyimide resin (cured product)]
The crosslinked polyimide resin is prepared by adding an amino compound having at least two primary amino groups of the component (B) as a functional group to the resin solution containing the polyimide resin having the ketone group of the component (A). It is produced by subjecting the ketone group of No. 1 to a condensation reaction with a primary amino group of an amino compound. By this condensation reaction, the resin solution (adhesive resin composition) is cured to become a cured product. In this case, the amount of the amino compound added is 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, more preferably the primary amino group, relative to 1 mol of the ketone group. The amino compound can be added in an amount of 0.03 mol to 0.9 mol, most preferably 0.04 mol to 0.5 mol. An adhesive containing a polyimide resin because the cross-linking of the polyimide resin by the amino compound is not sufficient with the addition amount of the amino compound such that the total number of primary amino groups is less than 0.004 mol with respect to 1 mol of the ketone group. Solder heat resistance tends to be less likely to develop in the cured product after the resin composition is cured, and when the amount of the amino compound added exceeds 1.5 mol, the unreacted amino compound acts as a thermoplastic agent and is cured. There is a tendency to reduce the solder heat resistance of a compound or the long-term heat resistance at high temperatures.

The conditions for the condensation reaction are as long as the ketone group in the (A) component polyimide resin reacts with the primary amino group of the amino compound in the (B) component to form an imine bond (C = N bond). , There are no particular restrictions. Although it depends on the type of the amino compound, for example, when an aliphatic amine is used as the amino compound of the component (B), it can be condensed with the ketone group in the polyimide resin even at room temperature, but the condensation reaction is carried out by heating. It is preferable to promote it. When an aliphatic amine is used as the amino compound of the component (B), it is preferable to carry out heat condensation in the range of, for example, 60 to 200 ° C., and when an aromatic amine is used, for example, the range of 120 to 220 ° C. It is preferable to carry out heat condensation in the room. The temperature of the heat condensation is, for example, 120 for the purpose of releasing the water generated by the condensation to the outside of the system, or for simplifying the condensation step when the heat condensation reaction is subsequently performed after the synthesis of the polyimide resin. The range of about 220 ° C. is preferable, and the range of 140 to 200 ° C. is more preferable. The reaction time is preferably about 1 hour 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 Nippon Spectroscopy). It can be confirmed by the decrease or disappearance of the absorption peak derived from the ketone group in the polyimide resin near ^-1 and the appearance of the absorption peak derived from the imine group near 1635 cm ^-1 .

The heat condensation between the ketone group of the polyimide resin of the component (A) and the primary amino group of the amino compound of the component (B) is, for example,
(A) Following the synthesis (imidization) of the polyimide resin, an amino compound is added and heated.
(B) An excessive amount of an amino compound is charged in advance as a diamine component, and the polyimide resin is heated together with the remaining amino compounds that are not involved in imidization (or amidization) following the synthesis (imidization) of the polyimide resin. Or,
(C) The composition of the polyimide resin to which the amino compound is added is processed into a predetermined shape (for example, after being applied to an arbitrary substrate or formed into a film) and then heated.
It can be done by such as.

In the case of (b) above, the excess amino compound is consumed in the reaction for sealing the acid anhydride group as a terminal substituent during the production of the polyimide resin, and the molecular weight of the produced polyimide resin may be extremely lowered. Therefore, it tends to be difficult to obtain sufficient heat resistance in the cured product. Therefore, when an excess amount of the amino compound is charged in advance [(b) above], it is preferable to use it appropriately within a range that does not impair the effect of the present invention. 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 into a polyimide resin as described in (a) or (c) above. It is preferable to add after completing (imidization). In the case of the above (c), the heat condensation is carried out by the heat of the heat treatment performed when forming the adhesive layer of the coverlay film with the composition in a state where the amino compound and the polyimide resin are mixed, or the adhesive layer is formed. After that, it can also be performed by utilizing heat or the like when thermocompression bonding is performed on a circuit board having a wiring layer.

[Inorganic filler]
The crosslinked polyimide resin can contain, as an arbitrary component (C), a plate-shaped inorganic filler having an average particle size in the range of 2 to 25 μm. When the crosslinked polyimide resin is used for the adhesive layer of a coverlay film, for example, by blending the inorganic filler of the component (C), the inorganic filler having a gas barrier property blocks the permeation of oxygen in the atmosphere. , Oxidation of copper wiring and diffusion of copper can be suppressed, and long-term heat resistance can be improved.

As the inorganic filler of the component (C), it is preferable to use a plate-shaped filler in order to impart sufficient gas barrier properties to the adhesive layer. Here, "plate-like" is used in the sense of including, for example, flat, flat, flaky, scaly, etc., and the thickness of the inorganic filler is sufficiently smaller than the major axis or minor axis of the flat portion (preferably). 1/2 or less). In particular, it is preferable to use a scaly inorganic filler. From another point of view, "plate-like" means that the ratio (major axis / thickness) of the major axis to the thickness of the filler particles is preferably 5 or more, more preferably 10 or more, still more preferably 15 or more. Further, in the plate-shaped inorganic filler, the relationship between the major axis and the average particle size is preferably major axis ≥ average particle size> 0.4 × major axis, and more preferably major axis ≥ average particle size ≧ 0.5 ×. It should have a major axis. 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 shall be the average value when any 10 filler particles are measured by a stereomicroscope. If the shape of the inorganic filler is not plate-shaped but spherical, for example, the gas barrier property of the adhesive layer may decrease, oxidation of the wiring layer may proceed, and the adhesive strength of the coverlay film may decrease. It does not prevent the blending of inorganic fillers having a shape other than the plate shape as long as the effect of blending the plate-shaped filler is not impaired.

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

The average particle size of the inorganic filler calculated by the laser diffraction method is preferably 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 size exceeds the above upper limit value, the surface of the adhesive layer of the coverlay film tends to be roughened, and when it is less than the above lower limit value, the effect of suppressing oxygen permeation is difficult to obtain.

The particle size distribution of the inorganic filler is preferably 60% or more, more preferably 65% or more, and preferably 20 μm or more, 10% or less, based on the number of particles. When the content of the inorganic filler having a particle size of 10 μm or less is less than 60%, when the adhesive resin composition is formed into a film, the fillers are lined up in layers, and protrusions appear on the film surface, which causes the film surface to be rough. Further, when the content of the inorganic filler having a particle size of 20 μm or more exceeds 10%, protrusions appear on the film surface and cause the film surface to be rough. For example, when a thin film having a particle size of 15 μm or less is produced, the surface tends to be rough. Cheap. The frequency distribution of the particle size of the inorganic filler is preferably 0.1 to 100 μm, more preferably 0.5 to 70 μm. When the frequency distribution exceeds the above upper limit value, the surface of the adhesive layer tends to be roughened, and when it is less than the above lower limit value, the effect of suppressing oxygen permeation is difficult to obtain.

The blending amount of the inorganic filler of the component (C) is 5 to 200 parts by weight, preferably 10 to 150 parts by weight, more preferably 10 to 150 parts by weight, based on 100 parts by weight of the total of the components (A) and (B). It is preferably 30 to 100 parts by weight, and preferably 40 to 80 parts by weight. If 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 components (A) and (B), the effect of blending cannot be obtained and the effect of suppressing oxygen permeation cannot be obtained. Further, if the blending amount of the inorganic filler exceeds 200 parts by weight with respect to 100 parts by weight of the total of the components (A) and (B), the adhesive layer becomes fragile, and as a result, cohesive failure in the adhesive layer occurs. Due to the decrease in strength due to the above, the apparent adhesiveness is significantly reduced. Further, although a plate-shaped inorganic filler is used in the present invention, a non-plate-shaped inorganic filler can also be used in combination. When a non-plate-shaped inorganic filler is used in combination, the total amount of the inorganic filler (total of plate-shaped and other shapes) exceeds 200 parts by weight with respect to 100 parts by weight of the components (A) and (B). It is preferable not to do so.

[Action]
In the crosslinked polyimide resin, the reaction between the ketone group of the polyimide resin of the component (A) and the primary amino group of the amino compound of the amino compound of the component (B) is a dehydration condensation reaction. That is, as a result of the carbon atom of the ketone group and the nitrogen atom of the primary amino group in the polyimide resin forming a C = N bond, the chain polyimide resin is crosslinked by the amino compound to form a network-like polymer. It is considered to be a thing. Since the polyimide resin does not easily cause intermolecular interaction, it is difficult to control the orientation of the polyimide resin. However, when such a crosslinked structure occurs, not only the apparent high molecular weight of the polyimide resin but also the molecules of the polyimide resin are used with each other. It is considered that the heat resistance of the polyimide resin is improved and extremely excellent solder heat resistance can be obtained because it is possible to restrain the polyimide resin to some extent. Further, since the vicinity of the nitrogen atom in the C = N bond becomes sterically bulky, the nucleophilic ability of the copper atom of the polar group contained in the polyimide resin is lowered, so that the copper adhesive layer from the copper wiring can be obtained. 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 this reason, 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. Further, in an amino compound having three or more amino groups, the crosslinked structure after the two amino groups form a C = N bond becomes sterically bulky, so that the remaining unreacted amino groups are ketone groups. It is particularly preferable that the number of amino groups is 2 because it becomes difficult to react with. Further, as described above, from the viewpoint of shortening the curing time of the adhesive resin composition, it is most preferable to use a dihydrazide compound as the amino compound.

Further, the crosslinked polyimide resin uses an aliphatic diamine, preferably a dimer diamine, as a raw material for synthesizing the polyimide resin, so that the flexibility and heat of the crosslinked polyimide resin are equal to or higher than those of the polyimide resin having a siloxane structure without using a siloxane diamine. It is possible to obtain characteristics such as adhesion durability to the resin. Therefore, it is possible to form a siloxane-free adhesive layer in which cyclic siloxane does not volatilize, which adversely affects electronic components. In the present invention, it is preferable not to use 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 an aliphatic diamine as a diamine component if it is possible to suppress the amount of volatile matter to a trace amount that does not adversely affect electronic components.

[Adhesive resin composition]
The adhesive resin composition contains a polyimide resin having a ketone group [(A) component] and an amino compound [(B) component] having at least two primary amino groups as functional groups as essential components. do. This adhesive resin composition is obtained by mixing or kneading the components (A) and (B) and / or heating in a state containing the components (A) and (B) to obtain the polyimide resin. It has the property that the ketone group of No. 1 and the primary amino group of the amino compound undergo a condensation reaction to form a C = N bond. That is, it changes into a crosslinked polyimide resin which is a cured product by a condensation reaction between the polyimide resin and the amino compound. In the adhesive resin composition, the weight average molecular weight of the component (A) is preferably 10,000 to 200,000, 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 used as 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 a solvent tends to be impaired.

The adhesive resin composition has a total of 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, and more preferably 0.03 of primary amino groups with respect to 1 mol of ketone groups. The amino compound can be contained in an amount of mol to 0.9 mol, particularly preferably 0.04 mol to 0.5 mol.

Further, it is preferable that the adhesive resin composition contains, in addition to the polyimide resin of the component (A) and the amino compound of the component (B), the inorganic filler of the component (C) as an optional component. Further, 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, it is preferable not to use a plasticizer as much as possible because some plasticizers contain a large amount of polar groups, which may promote the diffusion of copper from copper wiring.

When an arbitrary component other than the above component (C) is blended in the adhesive resin composition, for example, the blending amount of the optional component is 1 to 50 parts by weight in total with respect to 100 parts by weight of the polyimide resin of the component (A). It is preferable to use 2 to 7 parts by weight, and more preferably 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 by using the adhesive resin composition, for example, a wiring portion of an FPC, a rigid flex circuit board, or the like. It has preferable properties as an adhesive for a coverlay film that protects the film. When used as an adhesive layer for a coverlay film, the adhesive resin composition is applied to one side of the coverlay film material in a solution state (for example, in the form of a varnish containing a solvent), and then, for example, at 60 to 220 ° C. By thermocompression bonding at a temperature, a coverlay film having a coverlay film material layer and an adhesive layer can be formed. In this case, the ketone group of the polyimide resin of the component (A) and the primary amino group of the amino compound of the component (B) can be heat-condensed 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, the adhesive resin composition is applied on an arbitrary substrate in a solution state (for example, in the form of a varnish containing a solvent), dried at a temperature of, for example, 80 to 180 ° C., and then peeled off to adhere. An agent film is formed, and the adhesive film is thermocompression bonded to the coverlay film material at a temperature of, for example, 60 to 220 ° C. to obtain a coverlay film having a coverlay film material layer and an adhesive layer. Can be formed. Also in this case, the ketone group of the polyimide resin of the component (A) and the primary amino group of the amino compound of the component (B) can be heat-condensed by utilizing the heat at the time of thermocompression bonding. As described above, the adhesive resin composition is processed into various forms in a state where the ketone group of the polyimide resin of the component (A) and the primary amino group of the amino compound of the component (B) have not reacted. Available. Furthermore, the adhesive resin composition can also be used by forming a coating film in a solution state on any substrate by screen printing and drying it at a temperature of, for example, 80 to 180 ° C. It is also possible to form a cured product 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 coverlay film includes a coverlay film material and an adhesive layer composed of the adhesive resin composition laminated on the coverlay film material. The coverlay film material in the coverlay film is not limited, but includes, for example, a polyimide resin film such as a polyimide resin, a polyetherimide resin, and a polyamideimide resin, a polyamide resin film, and a 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.

Further, the adhesive resin composition formed in the form of a film can also be used, for example, as a bonding sheet for a multilayer FPC. When used as a bonding sheet, the adhesive resin composition is applied in a solution state on an arbitrary base film, dried at a temperature of, for example, 80 to 180 ° C., and then the adhesive film obtained by peeling is bonded as it is. It may be used as a sheet, or may be used in a state where this adhesive film is laminated with an arbitrary base film. Even when used as a bonding sheet, the ketone group of the polyimide resin and the primary amino group of the amino compound can be heat-condensed by using the heat during thermocompression bonding, and further heat treatment is performed after thermocompression bonding. It can also be heat-condensed.

Further, the coverlay film or the bonding sheet may be in a form in which a release material is bonded to the adhesive surface to have a release material layer. 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 or the bonding sheet, but for example, a resin film such as polyethylene terephthalate, polyethylene, polypropylene, or a resin film thereof. Can be used, such as those laminated on paper.

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

By using the coverlay film in 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 can be obtained.

Further, the circuit board may be configured as a multilayer circuit board. In this case, the 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, but it is necessary for the circuit after the metal foil of the metal-clad laminate such as a copper-clad laminate is circuit-processed into a predetermined pattern by a method such as chemical etching. Examples thereof include a method in which a coverlay film is laminated on various portions and thermocompression bonded using a hot press device or the like. In this case, the crimping conditions are not particularly limited, but for example, the crimping 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. Is preferable. In the state of the coverlay film, if the ketone group of the polyimide resin of the component (A) and the primary amino group of the amino compound of the component (B) have not reacted, the coverlay film is heated to the circuit wiring. A condensation reaction can be caused by utilizing the heat of crimping. That is, the adhesive layer of the coverlay film is arranged so as to be in contact with the wiring layer, and at the same time as the step of thermocompression bonding both members, the ketone group of the polyimide resin of the component (A) contained in the adhesive layer and (B). ) It is possible to form a C = N bond by subjecting it to a condensation reaction with a primary amino group of the amino compound of the component.

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]
For the adhesive strength, the adhesive surface of the test piece cut out to a width of 10 mm and a length of 100 mm was placed on a glossy surface (without rust-preventive metal) of a copper foil (thickness of 35 μm), and the temperature was 170 ° C. and the pressure was 1 MPa. Press under the condition of 1 minute time, then heat in the oven at a temperature of 150 ° C. and 6 hours time (however, for Reference Example 7, press under the conditions of temperature 170 ° C., pressure 1 MPa and 1 minute time, and then press. When peeling off at a speed of 50 mm / min in the 180 ° direction using a tensile tester (Strograph-M1 manufactured by Toyo Seiki Co., Ltd.) after heating in an oven at a temperature of 150 ° C. and a time of 24 hours). The force of 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.

[Warp evaluation method]
The warp was evaluated by the following method. A polyimide adhesive was applied onto a 25 μm-thick Kapton film so that the dried thickness would be 35 μm. In this state, the Kapton film was placed so as to be on the lower surface, and the average of the warped heights at the four corners of the film was measured.

The abbreviations used in this example indicate the following compounds.
BTDA: 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride BPDA: 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride ODPA: 4,4'-oxydiphthalic acid anhydride ( Alias; 5,5'-oxybis-1,3-isobenzofuranhydride)
BAPP: 2,2-bis (4-aminophenoxyphenyl) propane BAFL: bisaniline fluorene DDA: aliphatic diamine having 36 carbon atoms (manufactured by Claude Japan Co., Ltd., trade name; PRIAMINE1074, amine value; 205 mgKOH / g, cyclic structure And a mixture of diamine diamines having a chain structure, content of dimer components; 95% by weight or more)
N-12: Dihydrazide dodecanedioate ADH: Dihydrazide adipate K-1: Tarku (manufactured by Nippon Tarku Co., Ltd., trade name; MICRO ACE K-1, shape; scaly, average major diameter; 7.0 μm, average minor diameter; 5.8 μm, ratio of major axis to thickness; 15 or more, average particle diameter; 6.6 μm, median diameter (D50); 6.9 μm, maximum particle diameter; 64.9 μm, minimum particle diameter; 0.5 μm, most frequent Diameter: 8.7 μm, integrated particle amount of particle size 10 μm or less; 77%, integrated particle amount of particle size of 20 μm or more; 5%)

Example 1
A 3000 ml separable flask was charged with 111.96 g of BTDA (0.347 mol), 188.04 g of DDA (0.347 mol), 420 g of N-methyl-2-pyrrolidone and 280 g of xylene, 40. Mix well at ° C. for 1 hour to obtain a polyamic acid solution. The temperature of this polyamic acid solution was raised to 190 ° C., the mixture was 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 solid content in the obtained polyimide solution a was 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 of BPDA (0.359 mol), 194.34 g of DDA (0.359 mol), 420 g of N-methyl-2-pyrrolidone and 280 g of xylene, 40. Mix well at ° C. for 1 hour to obtain a polyamic acid solution. The temperature of this polyamic acid solution was raised 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 solid content in the obtained polyimide solution b was 29.5% by weight, and the weight average molecular weight (Mw) of the polyimide resin was 60,100.

Example 3
63.51 g of BTDA (0.197 mol), 61.14 g of ODPA (0.197 mol), 106.66 g of DDA (0.197 mol), 68.67 g of BAFL (0) in a 3000 ml separable flask. .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 temperature of this polyamic acid solution was raised to 190 ° C., the mixture was 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 solid content in the obtained polyimide solution c was 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 (50 g as a solid content) of the polyimide solution a obtained in Example 1 was mixed with 3.5 g of N-12 (0.014 mol) and 25 g of K-1, and 20.07 g of N-. Methyl-2-pyrrolidone was added to dilute the mixture, 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 x width x thickness = 200 mm x 300 mm x 25 μm), dried at 80 ° C. for 15 minutes, and adhered. A coverlay film 1 having a layer thickness of 25 μm was used. This coverlay film 1 is placed on a copper foil from which the rust-preventive metal layer on the surface has been removed, pressed under the 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 6 hours. The product was heated in 1 to obtain an evaluation sample 1. The adhesive strength with the copper foil after curing was 1.5 kN / m. In addition, there was no problem with the warp of the coverlay film. When the infrared absorption spectrum of the adhesive layer in the evaluation sample 1 was measured using a Fourier transform infrared spectrophotometer (commercially available: FT / IR620 manufactured by Nippon Spectroscopy), absorption of BTDA-derived ketone groups was observed near 1673 cm ^-1 . It was confirmed that the amount was decreased, and the absorption of imine groups was further confirmed around 1635 cm ^-1 .

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

[Reference Example 2]
A polyimide solution 2 was obtained in the same manner as in Reference Example 1 except that K-1 was not blended in place of 25 g of K-1 in Reference Example 1, and then the coverlay film 2 was applied. Obtained, and evaluation sample 2 was obtained. The adhesive strength with the copper foil after curing was 1.8 kN / m. In addition, there was no problem with the warp of the coverlay film.

Further, in the same manner as in Reference Example 1, a printed circuit board on which the circuit {wiring width / wiring interval (L / S) = 25 μm / 25 μm} is formed is prepared, and the coverlay film 2 obtained in Reference Example 2 is printed. A wiring board 2 provided with a coverlay film was obtained by placing it on the circuit surface of the board and thermocompression bonding.

[Reference Example 3]
Polyimide solution 3 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. In addition, there was no problem with the warp of the coverlay film.

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

[Reference example 4]
Polyimide solution 4 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. In addition, there was no problem with the warp of the coverlay film.

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

[Reference Example 5]
The 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 added instead of 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. In addition, there was no problem with the warp of the coverlay film.

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

[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 ( A polyimide solution 6 was obtained, a coverlay film 6 was obtained, and an evaluation sample 6 was obtained in the same manner as in Reference Example 1 except that 0.003 mol) was blended. The adhesive strength with the copper foil after curing was 1.0 kN / m. In addition, there was no problem with the warp of the coverlay film.

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

[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 added instead of 3.5 g of N-12 in Reference Example 1. rice field. Coverlay film 7 was obtained. The coverlay film 7 is placed on a copper foil from which the rust-preventive metal layer on the surface has been removed, pressed under the 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. The evaluation sample 7 was obtained. The adhesive strength with the copper foil after curing was 1.3 kN / m. In addition, there was no problem with the warp of the coverlay film.

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

Reference example 8
A polyimide solution was obtained in the same manner as in Reference Example 1 except that N-12 was not blended in place of 3.5 g of N-12 in Reference Example 1, and then a coverlay film was applied. Obtained 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 3.5 g of N-12 was blended, but N-12 was not blended. Except for this, a polyimide solution was obtained in the same manner as in Reference Example 1, and then a coverlay film was obtained to obtain an evaluation sample. This evaluation sample was evaluated in the same manner as in Reference Example 1.

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

The results of Reference Example 1 to Reference Example 10 are summarized in Tables 2 and 3. The molar ratio in Tables 2 and 3 means the total molar ratio of the primary amino groups in the amino compound to 1 mol of the ketone groups in the polyimide resin.

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

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. For example, in the above embodiment, as an example of the use of the crosslinked polyimide resin, an adhesive for a coverlay film or a bonding sheet of a circuit board such as an FPC is mentioned as an example, but an application other than the above, for example, tape automated bonding (TAB). ), It can also be used to form an adhesive resin in a chip size package (CSP) or the like.

Claims (5)

Adhesive resin composition for forming an adhesive layer on a circuit board, forming an adhesive layer on a multilayer circuit board, forming a bonding sheet applied to a multilayer circuit board, or forming an adhesive layer on a coverlay film on a circuit board. A method for producing a solvent-soluble polyimide resin used in a product.
A mixture of cyclic and chain-structured dimer diamines, a diamine component containing 50 mol% or more of an aliphatic diamine having 36 carbon atoms having a dimer component content of 95% by weight or more, and an aromatic tetracarboxylic acid anhydride. A precursor of a polyimide having a ketone group is obtained by dissolving a substance component in an organic solvent containing an aromatic hydrocarbon and stirring the mixture at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours to carry out a polymerization reaction. And the process of obtaining
Following the step, the step of imidizing the precursor of the polyimide having the ketone group in the organic solvent,
A method for producing a solvent-soluble polyimide resin having a ketone group, which comprises . The method for producing a solvent-soluble polyimide resin according to claim 1, wherein the precursor is imidized by a heat treatment in which the precursor is heated in the organic solvent at a temperature condition in the range of 80 to 300 ° C. for 1 to 24 hours. The method for producing a solvent-soluble polyimide resin according to claim 1 or 2, wherein the aromatic tetracarboxylic acid anhydride component contains a benzophenone tetracarboxylic acid anhydride. The method for producing a solvent-soluble polyimide resin according to any one of claims 1 to 3, wherein the solvent-soluble polyimide resin has a weight average molecular weight in the range of 20,000 to 150,000. The organic solvent is from N, N-dimethylformaldehyde, N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme and triglyme. The method for producing a solvent-soluble polyimide resin according to any one of claims 1 to 4, which comprises at least one selected from the group.