TWI749203B - Curable resin composition, laminate structure, cured product thereof, and electronic component - Google Patents

Abstract

The subject of the present invention is to provide a curable resin composition that satisfies the required performance of both solder resist and cover film, does not impair developability, has excellent heat resistance or low rebound properties, and has less warpage after heating . Furthermore, there is provided a curable resin composition which satisfies the required performance of both a solder resist and a cover film, and is excellent in developability (alkali solubility) or heat resistance (solder heat resistance). "The means for solving the problem is a curable resin composition containing an alkali-soluble polyimide resin, an alkali-soluble resin other than the polyimide resin, and a curable compound."

Description

Curable resin composition, laminated structure, its cured product, and electronic parts

The present invention relates to a curable resin composition (hereinafter also abbreviated as "composition") useful as an insulating film of electronic parts such as a flexible printed wiring board, a laminated structure, a cured product thereof, and electronic parts.

In recent years, due to the miniaturization and thinning of electronic devices due to the spread of smartphones and tablet terminals, it has gradually become necessary to reduce the space of electronic components such as circuit boards. Therefore, the use of flexible printed wiring boards that can be folded and housed has expanded, and even for flexible printed wiring boards, higher reliability than before has been required.

In response to this, as an insulating film for ensuring the insulation reliability of flexible printed wiring boards, it is widely used: the bending part (bending part) is made of polyamide which has excellent mechanical properties such as heat resistance and flexibility. Imine is used as the base cover film (for example, refer to Patent Documents 1 and 2), and the mounting part (non-bending part) is a mixed process using a photosensitive resin composition that is excellent in electrical insulation or solder heat resistance and can be finely processed .

That is, the cover film using polyimide as the base is not suitable for fine wiring because it needs to be processed by die punching. Therefore, it is necessary to use an alkali-developing photosensitive resin composition (solder resist) that can be processed by photolithography in combination with a chip mounting portion that requires fine wiring. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 62-263692 　　 [Patent Document 2] Japanese Patent Laid-Open No. 63-110224

[The problem to be solved by the invention]

In this way, in the manufacturing steps of the conventional flexible printed wiring board, a mixed process of laminating the cover film and forming the solder resist has to be used, and there are problems such as poor cost and workability. .

In this regard, it has been studied to apply an insulating film as a solder resist or an insulating film as a cover film to the solder resist and cover film of a flexible printed wiring board. However, the requirement for a small circuit board space can be fully satisfied. Materials that require performance of both solder resist and cover film have not yet been put into practical use.

In addition, the solder resist or cover film is required to have excellent developability (alkali solubility) or heat resistance (solder heat resistance), low rebound properties (resilience), and warpage after heating (warpage after curing). Various features such as small ones. However, in order to ensure heat resistance and at the same time improve low resilience or warpage after heating, if an alkali-soluble resin with a relatively large molecular weight is used, problems such as inability to develop will occur. In addition, although the imine-based resin has heat resistance, it has the disadvantage of large warpage after curing. Although the urethane-based resin is a resin with low resilience and low warpage , But there are problems such as poor heat resistance. Therefore, the use of various resin compositions proposed in the past cannot satisfy all requirements such as excellent heat resistance and low rebound properties without impairing the developability, and low warpage after heating.

Therefore, the main object of the present invention is to provide a curable resin composition that satisfies the required performance of both solder resist and cover film without compromising the developability, excellent heat resistance or low rebound, and less warpage after heating . In addition, another object of the present invention is to provide a curable resin suitable for insulating films such as flexible printed wiring boards (especially, a one-time forming process of a bent portion (curved portion) and a mounting portion (non-curved portion)) The composition, the laminated structure, the cured product thereof, and electronic components such as a flexible printed wiring board having the cured product as a protective layer such as a cover film or a solder resist. [Means to solve the problem]

As a result of intensive research in order to solve the above-mentioned problems, the inventors have completed the present invention having the following contents as the gist. "That is, the curable resin composition of the present invention is characterized by containing an alkali-soluble polyimide resin, an alkali-soluble resin other than the polyimide resin, and a curable compound.

(X₁ 為源自碳數24~48的二聚體酸的脂肪族二胺(a)的殘基，X₂ 為具有羧基的芳香族二胺(b)的殘基，Y分別獨立為環己烷環或芳香環)。In the curable resin composition of the present invention, the alkali-soluble resin other than the polyimide resin is preferably a polyamideimide resin, and the polyamideimide resin has the following The polyimide resin having the structure represented by the general formula (1) and the structure represented by the following general formula (2) is preferred.

(X ₁ is a residue of aliphatic diamine (a) derived from a dimer acid with a carbon number of 24 to 48, X ₂ is a residue of an aromatic diamine (b) having a carboxyl group, and Y is each independently a ring Hexane ring or aromatic ring).

Furthermore, the curable resin composition of the present invention preferably further contains core-shell rubber particles. Furthermore, in the curable resin composition of the present invention, the aforementioned polyimide resin preferably has a carboxyl group, and more preferably has a carboxyl group and a phenolic hydroxyl group.

Furthermore, in the curable resin composition of the present invention, the curable compound is preferably an epoxy resin.

In addition, the laminated structure of the present invention has a resin layer (A) and a resin layer (B) laminated on a substrate through the resin layer (A), and is characterized in that the resin layer (B) ) Is composed of the above-mentioned curable resin composition, and the aforementioned resin layer (A) is composed of an alkali-developable resin composition containing an alkali-soluble resin and a heat-reactive compound.

In addition, the cured product of the present invention is characterized by being composed of the above-mentioned curable resin composition or the above-mentioned laminated structure.

Furthermore, the electronic component of the present invention is characterized by having an insulating film made of the above-mentioned cured product.

Here, as the electronic component of the present invention, for example, a layer having the above-mentioned laminated structure formed on a flexible printed wiring board, patterned by light irradiation, and patterned at a time with a developer Insulating film formed. In addition, it is also possible to have a resin layer (A) and a resin layer (B) sequentially formed on a flexible printed wiring board without using the above-mentioned layered structure, and then patterned by light irradiation, and use An insulating film formed by the developer forming the pattern at one time. In the present invention, the term "pattern" refers to a pattern-like cured product, that is, it means an insulating film. [Effects of the invention]

According to the present invention, it is possible to provide a curable resin composition that satisfies the required performance of both solder resist and cover film, does not impair developability, is excellent in heat resistance or low rebound, and has less warpage after heating. In addition, a curable resin composition capable of realizing an insulating film suitable for electronic parts such as flexible printed wiring boards (especially, a one-time forming process of a bent portion (curved portion) and a mounting portion (non-curved portion)) Electronic parts such as flexible printed wiring boards having the cured product as a protective film such as a cover film or a solder resist.

[Best form to implement the invention]

Hereinafter, the embodiment of the present invention will be described in detail. (Curable resin composition) "The curable resin composition of the present invention contains an alkali-soluble polyimide resin, other alkali-soluble resins, and a curable compound. By making it contain alkali-soluble polyimide resin, other alkali-soluble resins, and curable compounds, it can meet the requirements of both solder resist and cover film, and achieve developability or heat resistance. It is an excellent curable resin composition.

(Alkali-soluble polyimide resin) 　　As the alkali-soluble polyimide resin, as long as it contains one or more functional groups of phenolic hydroxyl group and carboxyl group, and can be developed with an alkaline solution, it can be used Known and used.

With this polyimide resin, characteristics such as bending resistance and heat resistance become more excellent.

Examples of such alkali-soluble polyimide resins include resins obtained by reacting a carboxylic anhydride component with an amine component and/or an isocyanate component. Here, the alkali-soluble group is introduced by using an amine component having a carboxyl group or a phenolic hydroxyl group. In addition, the imidization system may be performed by thermal imidization, or may be performed by chemical imidization, or may be performed in combination with these.

Examples of the carboxylic anhydride component include tetracarboxylic anhydride, tricarboxylic anhydride, etc., but it is not limited to these anhydrides, as long as it is a compound having an acid anhydride group and a carboxyl group that react with an amino group or an isocyanate group, and it may be included. Derivatives to use. Moreover, these carboxylic anhydride components can be used individually or in combination.

As the amine component, diamines such as aliphatic diamines and aromatic diamines, polyamines such as aliphatic polyetheramines, diamines having carboxyl groups, diamines having phenolic hydroxyl groups, and the like can be used. The amine component is not limited to these amines, but it is necessary to use an amine into which at least one of a phenolic hydroxyl group and a carboxyl group can be introduced. In addition, these amine components can be used alone or in combination.

As the isocyanate component, diisocyanates such as aromatic diisocyanates and their isomers or polymers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers, or other widely used diisocyanates can be used, However, it is not limited to these isocyanates. In addition, these isocyanate components can be used alone or in combination.

For the synthesis of such alkali-soluble polyimide resins, well-known and customary organic solvents can be used. As such an organic solvent, there is no problem as long as it does not react with the carboxylic anhydrides, amines, and isocyanates of the raw materials and can dissolve the raw materials, and the structure is not particularly limited. In particular, because of the high solubility of raw materials, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylimide Aprotic solvents such as chrysene and γ-butyrolactone are preferred.

The alkali-soluble polyimide resin as described above has a good balance between the alkali solubility (developability) of the polyimide resin and the mechanical properties of the cured product of the resin composition containing the polyimide resin. From the standpoint of other characteristics of the product, the acid value (solid acid value) is preferably 20~200mgKOH/g, more suitably 60~150mgKOH/g. Specifically, by setting the acid value to 20 mgKOH/g or more, the alkali solubility (that is, developability) becomes better, and the crosslink density with the thermosetting component after light irradiation becomes higher, so A sufficient development contrast value can be obtained. In addition, by setting the acid value to 200 mgKOH/g or less, the so-called thermal fogging in the PEB (POST EXPOSURE BAKE) step after light irradiation described later can be suppressed, and the process margin can be increased.

In addition, for the molecular weight of such alkali-soluble polyimide resins, considering the developability and the characteristics of the cured coating film, the mass average molecular weight Mw is preferably 100,000 or less, preferably 1,000 to 100,000, and 2,000 ~50,000 is better. If the molecular weight is 100,000 or less, the alkali solubility of the unexposed part will increase, and the developability will improve. On the other hand, if the molecular weight is 1,000 or more, after the exposure and PEB step, sufficient development resistance and hardened physical properties can be obtained in the exposed part.

(Alkali-soluble resins other than polyimide resins) 　　As such alkali-soluble resins, as long as they contain one or more functional groups among phenolic hydroxyl groups and carboxyl groups, and can be developed with an alkaline solution, You can use well-known and customary users. For example, a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin which has been conventionally used in solder resists can be used.

In particular, from the viewpoint of obtaining a resin composition that does not impair developability and has better characteristics such as bending resistance and heat resistance, alkali-soluble polyimide resins can be suitably used. By using such an alkali-soluble polyimide resin in combination with the aforementioned alkali-soluble polyimide resin, it is possible to provide excellent heat resistance or low rebound without impairing the developability, but also low A curable resin composition that is dielectric and has a small warpage after heating.

Here, as the mixing ratio of the alkali-soluble polyimide resin and the aforementioned alkali-soluble polyimide resin, the mass ratio can be set to 98:2-50:50, so as to be 90:10 ~50: 50 is better.

(Alkali-soluble polyimide resin) 　　 In the curable resin composition of the present invention, as an alkali-soluble polyimide resin, as long as it contains one or more functional groups of phenolic hydroxyl group and carboxyl group And those who can use alkaline solution to develop can use well-known and customary ones. Such alkali-soluble polyamide resins include, for example, a resin obtained by reacting a carboxylic anhydride component with an amine component to obtain an amide compound, and then reacting the obtained amide compound with an isocyanate component. Wait. Here, the alkali-soluble group is introduced by using an amine component having a carboxyl group or a phenolic hydroxyl group. In addition, the imidization system may be performed by thermal imidization, or may be performed by chemical imidization, or may be performed in combination with these.

Examples of the carboxylic anhydride component include tetracarboxylic anhydride, tricarboxylic anhydride, etc., but it is not limited to these anhydrides, as long as it is a compound having an acid anhydride group and a carboxyl group that react with an amino group or an isocyanate group, and it may be included. Derivatives to use. Moreover, these carboxylic anhydride components can be used individually or in combination.

As the amine component, diamines such as aliphatic diamines and aromatic diamines, polyamines such as aliphatic polyetheramines, diamines having carboxyl groups, diamines having phenolic hydroxyl groups, and the like can be used. The amine component is not limited to these amines, but it is necessary to use an amine into which at least one of a phenolic hydroxyl group and a carboxyl group can be introduced. In addition, these amine components can be used alone or in combination.

As the isocyanate component, diisocyanates such as aromatic diisocyanates and their isomers or polymers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers, or other widely used diisocyanates can be used, However, it is not limited to these isocyanates. In addition, these isocyanate components can be used alone or in combination.

The alkali-soluble polyimide resin as described above has a good balance between the alkali solubility (developability) of the polyimide resin and the resin composition containing the polyimide resin. From the viewpoint of other properties such as the mechanical properties of the cured product, the acid value (solid content acid value) is preferably set to 30mgKOH/g or more, and more preferably set to 30mgKOH/g~150mgKOH/g. It is particularly preferable to set it as 50mgKOH/g~120mgKOH/g. Specifically, by setting the acid value to 30 mgKOH/g or more, the alkali solubility (that is, developability) becomes better, and the crosslink density with the thermosetting component after light irradiation becomes higher, so A sufficient development contrast value can be obtained. In addition, by setting the acid value to 150 mgKOH/g or less, the so-called thermal atomization in the PEB (POST EXPOSURE BAKE) step after light irradiation described later can be suppressed, and the process margin can be increased.

In addition, the molecular weight of the alkali-soluble polyimide resin, considering the developability and the characteristics of the cured coating film, the mass average molecular weight is preferably 20,000 or less, preferably 1,000 to 15,000, and 2,000 to 10,000 For better. If the molecular weight is 20,000 or less, the alkali solubility of the unexposed part will increase, and the developability will improve. On the other hand, if the molecular weight is 1,000 or more, after the exposure and PEB step, sufficient development resistance and hardened physical properties can be obtained in the exposed part.

Particularly in the present invention, in terms of further improving the developability, a polyimide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2) is used For and better.

Here, X ₁ is a residue of an aliphatic diamine (a) derived from a dimer acid with a carbon number of 24 to 48 (also referred to as "dimerdiamine (a)" in this specification) . X ₂ is a residue of an aromatic diamine (b) having a carboxyl group (also referred to as "a carboxyl group-containing diamine (b)" in this specification). The Y system is each independently a cyclohexane ring or an aromatic ring.

By including the structure represented by the above general formula (1) and the structure represented by the above general formula (2), it can be an alkali-soluble solution that can be dissolved even in a mild alkaline solution such as a 1.0% by mass sodium carbonate aqueous solution. Polyimide resin with excellent properties. In addition, a cured product of a resin composition containing such a polyamideimide resin can have excellent dielectric properties.

The dimer diamine (a) can be obtained by reductive amination of the carboxyl group in the dimer of the aliphatic unsaturated carboxylic acid having 12 to 24 carbon atoms. That is, the dimer diamine (a) of the aliphatic diamine derived from the dimer acid can be made into a dimer acid by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid. After reduction, it is obtained by amination. As such aliphatic diamines, for example, commercially available products such as PRIAMINE 1073, 1074, and 1075 (manufactured by Croda Japan, trade name) of diamines having a skeleton with 36 carbon atoms can be used. The dimer diamine (a) is preferably a dimer acid derived from a carbon number of 28 to 44, and there are cases where a dimer acid derived from a carbon number of 32 to 40 is more preferable.

As specific examples of the carboxyl group-containing diamine (b), 3,5-diaminobenzoic acid, 3,4-diaminobenzoic acid, 5,5'-methylenebis(anthranilic acid ), benzidine-3,3'-dicarboxylic acid, etc. The carboxyl group-containing diamine (b) system may be composed of one type of compound, or may be composed of multiple types of compounds. From the viewpoint of the availability of raw materials, the carboxyl group-containing diamine (b) preferably contains 3,5-diaminobenzoic acid and 5,5'-methylenebis(anthranilic acid).

In the polyimide resin, the relationship between the content of the structure represented by the general formula (1) and the content of the structure represented by the general formula (2) is not limited. From the viewpoint of a good balance of the alkali solubility of the polyimide resin and the mechanical properties of the cured product of the resin composition containing the polyimide resin, the dimer diamine ( The content of a) (unit: mass%) is preferably 20-60% by mass, and more preferably 30-50% by mass. In this specification, the so-called "dimer diamine (a) content" means that relative to the mass of the polyimide resin produced, it is positioned as the quality of the polyimide resin produced. The ratio of the feed amount of the dimer diamine (a) of one kind of the raw material. Here, "the quality of the polyimide resin produced" refers to the amount of all the raw materials used to make the polyimide resin is subtracted from the amount produced by imidization The value after the theoretical amount of water (H ₂ O) and carbon dioxide gas (CO _{2) generated by amination.}

From the viewpoint of improving the alkali solubility of the polyimide resin, the part represented by Y in the above general formula (1) and the above general formula (2) preferably has a cyclohexane ring. From the viewpoint of a good balance between the alkali solubility of the polyimide resin and the mechanical properties of the cured product of the resin composition containing the polyimide resin, it is represented by Y above The relationship between the aromatic ring and the amount of cyclohexane ring in the part, the molar ratio of the aromatic ring content relative to the content of the cyclohexane ring is preferably 85/15~100/0, and 90/10 ~99/1 is more preferable, and 90/10~98/2 is more preferable.

於此，X₃ 為二聚體二胺(a)及含有羧基的二胺(b)以外的二胺(f)(本說明書中亦稱為「其他的二胺(f)」)的殘基；Y係與上述一般式(1)及上述一般式(2)相同地分別獨立為芳香環或環己烷環。其他的二胺(f)係可以是由1種類的化合物所構成、也可以是由多種類的化合物所構成。The polyimide resin may further have a partial structure represented by the following general formula (i).

Here, X ₃ is the residue of the diamine (f) other than the dimer diamine (a) and the carboxyl-containing diamine (b) (also referred to as "other diamine (f)" in this specification) ; Y is the same as the above general formula (1) and the above general formula (2), respectively, independently of an aromatic ring or a cyclohexane ring. The other diamine (f) system may be composed of one type of compound, or may be composed of multiple types of compounds.

As specific examples of other diamines (f), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy) Phenyl] chrysene, bis[4-(4-aminophenoxy)phenyl] chrysene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, bis[4 -(4-Aminophenoxy)phenyl]methane, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ether , Bis[4-(4-aminophenoxy)phenyl]ketone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene , 2,2'-Dimethylbiphenyl-4,4'-diamine, 2,2'-Bis(trifluoromethyl)biphenyl-4,4'-diamine, 2,6,2', 6'-tetramethyl-4,4'-diamine, 5,5'-dimethyl-2,2'-sulfonyl-biphenyl-4,4'-diamine, 3,3'-diamine Hydroxybiphenyl-4,4'-diamine, (4,4'-diamino)diphenyl ether, (4,4'-diamino)diphenyl sulfide, (4,4'-diamine Yl)benzophenone, (3,3'-diamino)benzophenone, (4,4'-diamino)diphenylmethane, (4,4'-diamino)diphenyl Aromatic diamines such as ethers and (3,3'-diamino)diphenyl ethers, including hexamethylene diamine, octamethylene diamine, decamethylene diamine, dodecane Methyl diamine, stearyl methylene diamine, 4,4'-methylene bis (cyclohexyl amine), isophorone diamine, 1,4-cyclohexane diamine, norbornene diamine, etc. Aliphatic diamine.

The polyimide resin system may have a structure represented by the following general formula (ii).

Here, Z may be an aliphatic group or an aromatic group. In the case of an aliphatic group, an alicyclic group such as a cyclohexane ring may also be included. According to the production method described later, the Z system becomes the residue of the diisocyanate compound (e).

The method for producing the above-mentioned polyamide resin is not limited, and it can be produced through a step of imidization and a step of imidization using a well-known and commonly used method.

In the imidization step, dimer diamine (a), carboxyl-containing diamine (b), and cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) After reacting with one or two selected from the group of trimellitic anhydride (d), an imide compound is obtained.

The feeding amount of the dimer diamine (a) is preferably such that the content of the dimer diamine (a) becomes 20-60% by mass, and the content of the dimer diamine (a) is 30~ An amount of 50% by mass is more preferable. The definition of the content of the dimer diamine (a) is as described above.

If necessary, other diamines (f) can be used simultaneously with the dimer diamine (a) and the carboxyl-containing diamine (b).

From the viewpoint of improving the alkali solubility of polyimide resins, the use of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) in the imidization step is more important. good. The usage amount of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c), relative to the usage amount of trimellitic anhydride (d), is preferably 85/15~100/ in molar ratio 0, 90/10~99/1 is more preferable, and 90/10~98/2 is more preferable.

The diamine compound (B) used to obtain the imide compound (A) (specifically, means the dimer diamine (a), the carboxyl-containing diamine (b), and other necessary The amount of diamine (f)) and acid anhydride (C) (specifically, it means that cyclohexane 1,2,4-tricarboxylic acid 1,2-anhydride (c) and trimellitic anhydride (d) The relationship between the amount of one or two selected from the group is not limited. The amount of acid anhydride (C) used is preferably 2.0 or more and 2.4 in molar ratio relative to the amount of diamine compound (B) used, and the molar ratio is 2.0 or more and 2.2 or less. good.

In the amide imidization step, the amide compound (A) obtained by the above-mentioned amide imidization step is reacted with the diisocyanate compound (e) to obtain a compound having the following general formula ( 3) Polyimide resin of the structure shown.

The specific kind of diisocyanate compound (e) is not limited. The diisocyanate compound (e) may be composed of one type of compound, or may be composed of multiple types of compounds.

Specific examples of the diisocyanate compound (e) include 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and naphthalene-1,5-diisocyanate , O-xylene diisocyanate, m-xylene diisocyanate, 2,4-toluene dimer and other aromatic diisocyanates; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexyl Aliphatic diisocyanates such as methane diisocyanate, isophorone diisocyanate, norbornene diisocyanate, etc. From the viewpoint of improving the alkali solubility of the polyamide resin and the light penetration of the polyamide resin, the diisocyanate compound (e) preferably contains an aliphatic isocyanate The diisocyanate compound (e) is preferably an aliphatic isocyanate.

The amount of the diisocyanate compound (e) used in the imidization step is not limited. From the viewpoint of imparting moderate alkali solubility to the polyimide imide resin, the amount of the diisocyanate compound (e) used is relative to the diamine compound used for obtaining the imine compound (A) ( The amount of B) is preferably 0.3 or more and 1.0 or less in terms of molar ratio, more preferably 0.4 or more and 0.95 or less, and particularly preferably 0.50 or more and 0.90 or less.

The polyimide resin produced in this way contains a substance having a structure represented by the following general formula (3).

In the above general formula (3), X series are independently diamine residues (residues of diamine compound (B)), Y series are independently aromatic rings or cyclohexane rings, and Z series diisocyanate compounds (e) Residues. n is a natural number.

(Curable compound) "The curable resin composition system of the present invention further includes a curable compound. As the curable compound, a well-known and commonly used compound having a functional group capable of undergoing a curing reaction by heat or light can be used. Examples include thermosetting compounds having functional groups such as cyclic (thio) ether groups that can undergo a curing reaction by heat, and those having ethylenically unsaturated double bond groups that can undergo curing reactions by light. Among the photocurable compounds of functional groups, thermosetting compounds, especially epoxy resins, are preferred. Examples of the epoxy resin include bisphenol A epoxy resin, brominated epoxy resin, novolac epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, and glycidyl amine. Type epoxy resin, hydantoin type epoxy resin, alicyclic epoxy resin, trihydroxyphenylmethane type epoxy resin, dixylenol type or biphenyl type epoxy resin or a mixture of these; Phenol S type epoxy resin, bisphenol A novolac type epoxy resin, heterocyclic epoxy resin, biphenol novolac type epoxy resin, naphthyl-containing epoxy resin, epoxy resin with a dicyclopentadiene skeleton Resin etc.

Especially when a thermosetting compound is used, the equivalent ratio of such thermosetting compound to alkali-soluble resin (polyimide resin, polyimide resin, etc.) (alkali solubility of carboxyl groups, etc.) The group: a thermosetting group such as an epoxy group) is preferably blended in a ratio of 1:0.1 to 1:10. By setting it to such a blending ratio, the developability is good, and the fine pattern can be easily formed. The above-mentioned equivalent ratio is preferably 1:0.2~1:5.

(Core-shell rubber particles) "The curable resin composition of the present invention preferably further contains core-shell rubber particles. Accordingly, it will be possible to provide a curable resin composition which is excellent in developability and heat resistance and is suitable for use as an insulating film for electronic parts such as flexible printed wiring boards. For example, it can meet the requirements of solder resist and coating. The required performance of both membranes.

The core-shell rubber particles constituting the curable resin composition of the present invention have a function of not reducing adhesion and improving flexibility with the core-shell rubber particles.　　The so-called core-shell rubber particles refer to a rubber material with a multi-layer structure composed of a core layer of different compositions and a shell layer of 1 or more covering the core layer. As described later, the core-shell rubber particles are formed by using a material with excellent flexibility to form the core layer, and by using a material with excellent affinity for other components to form the shell layer, so as to be carried by the compounded rubber component. At the same time that the elastic modulus is lowered, the dispersibility is also good. By blending such core-shell rubber particles with the combination of the characteristics of the present invention, even in the state of heat treatment such as reflow, it can provide excellent results with no cracks during excessive bending tests. The soft hardened material can exhibit unique effects that the prior art does not have.

As a constituent material of the core layer, a material excellent in flexibility can be used. Specifically, silicone-based elastomers, butadiene-based elastomers, styrene-based elastomers, acrylic-based elastomers, polyolefin-based elastomers, polysiloxane/acryl-based composite elastomers, and the like can be cited.

On the other hand, as a constituent material of the shell layer, a material having excellent affinity for other components can be used. For example, when the curable resin composition contains epoxy resin, it is preferable to use core-shell rubber particles having a shell layer composed of a material having excellent affinity for epoxy resin. Furthermore, acrylic resin and epoxy resin are preferable.

Such a core-shell rubber particle preferably has a hardening reactive group on the surface from the viewpoint of storage stability. As such a hardening reactive group, it may be a thermosetting reactive group or a light curing group. Sexual reaction group. In addition, the core-shell rubber particle system may have two or more types of sclerosing reaction groups.

Examples of the thermosetting reactive group include a hydroxyl group, a carboxyl group, an isocyanate group, an imino group, an epoxy group, an oxetanyl group, a mercapto group, a methoxymethyl group, a methoxyethyl group, and an ethoxymethyl group. Group, ethoxyethyl, oxazolinyl, etc. It is also preferably an epoxy group.

As a photocurable reaction group, a vinyl group, a styryl group, a methacryl group, an acryl group, etc. are mentioned. Even when the filler content is large, since the reactivity is appropriate, the methacrylic acid group and the acrylic acid group are preferably used.

Here, the method of introducing the curable reactive group to the surface of the core-shell rubber particles is not particularly limited, and a well-known and usual method can be used. For example, when a shell layer is formed around the core layer, the constituent material of the shell layer can be introduced by polymerizing a material having a curable reactive group different from the functional group used for the polymerization reaction with the core layer To the core layer.

As a commercially available product of the core-shell rubber particles, Paraloid ELX2655 manufactured by Rohm and Haas, XER-91 manufactured by Nippon Synthetic Rubber Co., Ltd., and the like can be cited.

In the curable resin composition of the present invention, since the crack resistance is excellent, the average particle diameter of the core-shell rubber particles is preferably 2 μm or less. It is more preferably 0.01 to 1 μm. In this specification, the average particle size refers to the value of D 50 measured with a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd.

In the curable resin composition of the present invention, the content of the core-shell rubber particles is preferably 1 to 30% by mass per unit organic component in the solid content of the composition. If it is 1% by mass or more, it is preferable that the crack resistance is excellent. On the other hand, if it is 30% by mass or less, it is preferable in terms of excellent printability and developability. It is more preferably 3 to 20% by mass. Furthermore, the curable resin composition system of the present invention may contain core-shell rubber particles having a curable reactive group and rubber particles not having a core-shell. Here, the organic component refers to all solid components other than inorganic components such as fillers.

(Photopolymerization initiator) "When the curable resin composition of the present invention is used as a photosensitive resin composition, it is preferable to further include a photopolymerization initiator. As the photopolymerization initiator, well-known and customary ones can be used. In particular, when the curable resin composition of the present invention is applied to the PEB step after light irradiation described later, it can be used as a photobase generator. A functional photopolymerization initiator is suitable. Furthermore, in this PEB step, a photopolymerization initiator and a photobase generator can be used in combination.

The photopolymerization initiator, which also functions as a photobase generator, is irradiated with light such as ultraviolet rays or visible light to change the molecular structure, or by cleavage of the molecule, thereby generating a compound capable of acting as a curable (ie, thermal The curable compound) is a compound of one or more basic substances that functions as a catalyst for the polymerization reaction. Examples of basic substances include secondary amines and tertiary amines. As such a photopolymerization initiator that also has the function of a photobase generator, for example, an α-aminoacetophenone compound, an oxime ester compound, or an oxyimino group, N-methylated aromatic Compounds with substituents such as amine groups, N-acylated aromatic amine groups, nitrobenzyl carbamate groups, and alkoxybenzyl carbamate groups. Among them, oxime ester compounds and α-amine acetophenone compounds are preferred, and oxime ester compounds are more preferred. As the α-amine acetophenone compound, those having two or more nitrogen atoms are particularly preferred.

The α-amine acetophenone compound may be any compound that has a benzoin ether bond in the molecule and causes cleavage in the molecule when irradiated with light to generate a basic substance (amine) that functions as a hardening catalyst.

As the oxime ester compound, any compound can be used as long as it generates a basic substance by light irradiation.

Such a photopolymerization initiator may be used individually by 1 type, and may be used in combination of 2 or more types. The compounding amount of the photopolymerization initiator in the resin composition is preferably 0.1 to 40 parts by mass, and more preferably 0.3 to 15 parts by mass relative to 100 parts by mass of the total amount of the alkali-soluble resin. If it is 0.1 parts by mass or more, the comparative value of the development resistance of the light-irradiated part/non-irradiated part can be obtained well. In addition, if it is 40 parts by mass or less, the properties of the cured product will be improved.

In the curable resin composition of the present invention, the following components can be further blended as required.

(Polymer resin) "The curable resin composition of the present invention can be formulated with a known and customary polymer resin for the purpose of improving the flexibility and dryness to the touch of the cured product obtained. Examples of such polymer resins include cellulose, polyester, phenoxy resin polymers, polyvinyl acetal, polyvinyl butyral, polyamide, and polyamide. Imide-based adhesive polymers, elastomers, etc. Such a polymer resin may be used singly, or two or more types may be used in combination.

(Inorganic filler) "In the curable resin composition of the present invention, an inorganic filler can be formulated in order to suppress the curing shrinkage of the cured product and improve the properties such as adhesion and hardness. As such inorganic fillers, for example, barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, alumina, aluminum hydroxide, nitriding Silicon, aluminum nitride, boron nitride, Neuburg diatomaceous earth, etc.

(Coloring agent) "The curable resin composition of the present invention can be formulated with well-known and customary coloring agents such as red, orange, blue, green, yellow, white, and black. As such a coloring agent, any of pigments, dyes, and pigments may be used.

(Organic solvent) "The curable resin composition of the present invention can be equipped with an organic solvent for the preparation of the resin composition or for adjusting the viscosity for coating on a substrate or a carrier film. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, and the like. Such an organic solvent system may be used individually by 1 type, and may be used as a mixture of 2 or more types.

(Other components) "The curable resin composition of the present invention may further contain components such as mercapto compounds, adhesion promoters, thermosetting catalysts, antioxidants, and ultraviolet absorbers as required. These systems can use well-known and customary ones. In addition, well-known and customary thickeners such as micropowdered silica, hydrotalcite, organic bentonite, microcrystalline kaolin, etc., defoamers and/or leveling agents such as silicone, fluorine, and polymer can be formulated Well-known and customary additives such as silane coupling agent, rust inhibitor, etc.

The curable resin composition of the present invention having the above-explained structure can be suitably used to form the resin layer (B) in the laminate structure described below, and the laminate structure has the resin layer (A) , And the resin layer (B) laminated on the flexible printed wiring board through the resin layer (A).

(Laminated structure) "The laminated structure of the present invention has a resin layer (A) and a resin layer (B) laminated on a base material such as a flexible printed wiring board through the resin layer (A). "Here, in the laminated structure of the present invention, the resin layer (A) and the resin layer (B) substantially function as an adhesive layer and a protective layer, respectively. While the resin layer (B) is made of the above-mentioned curable resin composition, the resin layer (A) is made of an alkali-developable resin composition containing an alkali-soluble resin and a heat-reactive compound. This is the present invention The characteristics of the laminated structure.

In the present invention, in a laminate structure formed by laminating two resin layers, the upper resin layer (B) in the laminate structure is made of the curable resin composition of the present invention. By this, it is possible to achieve excellent heat resistance without impairing developability. In addition, polyimide resins are used as alkali-soluble resins other than polyimide resins, which can provide excellent heat resistance or low rebound without impairing the developability, and at the same time, it can be used after heating. The warpage becomes smaller. Furthermore, by including core-shell rubber particles in the curable resin composition of the present invention, it is possible to obtain a laminated structure having excellent developability and heat resistance, especially flexibility after solder reflow. body. If the resin layer (A) on the lower layer side of the laminated structure contains core-shell rubber particles, the adhesion may be reduced, but it is made of the above-mentioned curable resin composition containing core-shell rubber particles In the case of the resin layer (B) on the upper layer side, the adhesiveness is not reduced by this, and the effect of improving the flexibility by the core-shell rubber particles can be obtained. Therefore, in the present invention, it is preferable that the resin layer (A) does not contain core-shell rubber particles.

[Resin layer (A)] (Alkali-developing resin composition) 　　 As the alkali-developing resin composition constituting the resin layer (A), as long as it contains an alkali-soluble resin and a heat-reactive compound, it can be developed with an alkali solution The resin composition is sufficient. As a preferable alkali-soluble resin, the resin composition containing the compound which has a phenolic hydroxyl group, the compound which has a carboxyl group, and the compound which has a phenolic hydroxyl group and a carboxyl group is mentioned, A well-known and usual thing can be used.

For example, a resin composition containing a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin, a compound having an ethylenically unsaturated bond, and a heat-reactive compound, which has been conventionally used as a solder resist composition, can be cited.

Here, as the carboxyl group-containing resin or the carboxyl group-containing photosensitive resin, and the compound having an ethylenically unsaturated bond, well-known and commonly used compounds can be used, and as the thermoreactive compound, a cyclic (thio)ether can be used A well-known and commonly used compound such as a functional group that can undergo a curing reaction by heat.

Although such a resin layer (A) may or may not contain a photopolymerization initiator, as the photopolymerization initiator used when the photopolymerization initiator is included, it may be combined with the above-mentioned curable resin composition. The photopolymerization initiator used is the same.

The resin layer (A) may contain other components that are the same as the above-mentioned curable resin composition, such as polymer resins, inorganic fillers, colorants, and organic solvents.

[Resin layer (B)] The 　　 resin layer (B) is formed of the aforementioned curable resin composition containing alkali-soluble polyimide resin, other alkali-soluble resins, and a curable compound, There are no special restrictions on other points.

Here, as the above-mentioned alkali-soluble polyimide resin, other alkali-soluble resins, curable compounds, etc., the same resins and compounds as the curable resin composition constituting the present invention can be used. In addition, the curable resin composition constituting the resin layer (B) preferably contains alkali-soluble resins other than polyimide resin, more preferably contains polyimide resin, and more preferably contains polyimide resin. The polyimide resin having the structure represented by the aforementioned general formula (1) and the structure represented by the aforementioned general formula (2). With such a configuration, it is possible to obtain a resin composition that does not impair developability and has more excellent characteristics such as bending resistance and heat resistance.

Since the laminated structure of the present invention is excellent in flexibility, it can be used for at least one of the bent and non-bent parts of electronic parts such as flexible printed wiring boards, and can be used as, for example, flexible printed wiring. At least any one of the cover film, solder resist and interlayer insulating material of the board.

The laminated structure of the present invention formed as described above is preferably used as a dry film in which at least one side is supported or protected by a film.

(Dry film) "Dry film" can be manufactured in the following manner, for example. That is, first, the curable resin composition constituting the resin layer (B) and the alkali developable resin composition constituting the resin layer (A) are respectively diluted with an organic solvent, and adjusted to an appropriate viscosity. According to a conventional method, a doctor blade is used. A well-known technique such as coating is sequentially applied to the carrier film (support film). After that, usually by drying at a temperature of 50 to 130° C. for 1 to 30 minutes, a dry film in which the resin layer (B) and the resin layer (A) are formed on the carrier film can be produced. On this dry film, for the purpose of preventing dust and the like from adhering to the surface of the coating film, a peelable cover film (protective film) may be further laminated. As the carrier film and the cover film, conventionally known plastic films can be suitably used. Regarding the cover film, when the cover film is peeled off, it is better to be smaller than the adhesive force between the resin layer and the carrier film. There are no particular restrictions on the thickness of the carrier film and the cover film, but it is usually selected appropriately in the range of 10 to 150 μm.

(Cured product) "The cured product of the present invention is obtained by curing the aforementioned curable resin composition of the present invention or the aforementioned laminated structure of the present invention.

(Electronic component) "The curable resin composition and laminate structure of the present invention as described above can be effectively used in electronic components such as flexible printed wiring boards. Specifically, it can be exemplified by having a layer forming the curable resin composition or laminated structure of the present invention on a flexible printed wiring substrate, and patterning by light irradiation and patterning with a developing solution. Flexible printed wiring boards and the like of hardened insulating films.　　 Hereafter, as an example of electronic parts, the method of manufacturing a flexible printed wiring board will be described in detail.

(Method of Manufacturing Flexible Printed Wiring Board) "The manufacturing of a flexible printed wiring board using the laminated structure of the present invention can be performed in accordance with the procedure shown in the step diagram of FIG. 1, for example. That is, the manufacturing method includes the following steps: a step of forming a layer of the laminated structure of the present invention on a flexible printed wiring substrate on which a conductor circuit has been formed (a lamination step); The step of irradiating the layer of the layer with active energy rays in a pattern (exposure step); and the step of forming the layer of the patterned layered structure by alkali development of the layer of the layered structure (developing step) ). In addition, as required, photo-curing or thermal curing (post-curing step) is further performed after alkali development to completely cure the layer of the laminated structure, thereby obtaining a flexible printed wiring board with high reliability.

In addition, the manufacturing of the flexible printed wiring board using the laminated structure of the present invention can also be performed in accordance with the procedure shown in the step diagram of FIG. 2, for example. That is, the manufacturing method includes the following steps: a step of forming a layer of the laminated structure of the present invention on a flexible printed wiring substrate on which a conductor circuit has been formed (a lamination step); The step of irradiating the layer of the layered structure with active energy rays in a pattern (exposure step); the step of heating the layer of the layered structure (heating (PEB) step); and, the layer of the layered structure is subjected to alkali development, Thereby, the step of forming the layer of the patterned layered structure (development step). In addition, as required, photo-curing or thermal curing (post-curing step) is further performed after alkali development to completely cure the layer of the laminated structure, thereby obtaining a flexible printed wiring board with high reliability.

Hereinafter, each step in FIG. 1 or FIG. 2 will be described in more detail. [Laminating Step] In this step, a laminated structure is formed on the flexible printed wiring substrate 1 on which the conductor circuit 2 has been formed, and the laminated structure system is composed of the following layers: including alkali dissolution A resin layer 3 (resin layer (A)) made of an alkali-developable resin composition such as a synthetic resin, and a resin layer 4 (resin layer (B )). Here, each resin layer constituting the laminated structure can be formed by, for example, coating and drying the resin composition constituting the resin layers 3 and 4 on the wiring substrate 1 in order to form the resin layer 3 , 4, or a method in which the resin composition constituting the resin layers 3 and 4 is formed into a two-layered dry film form and laminated on the wiring base material 1.

As a method of applying the resin composition to the wiring substrate, known methods such as blade coating, lip tip coating, blade coating, and film coater can be used. In addition, the drying method can be a method of convective contact with hot air in the dryer using a heat source equipped with a steam heating method such as a hot air circulation drying oven, an IR furnace, a heating plate, a convection constant temperature oven, and a nozzle The method of blowing to the support is a well-known method.

[Exposure Step] "In this step, the photopolymerization initiator contained in the resin layer 4 is activated into a negative pattern by irradiation of active energy rays, thereby curing the exposed portion. In the case of using the composition of the PEB step described later, a photopolymerization initiator or a photobase generator having a function as a photobase generator is activated into a negative pattern to generate alkali.　　As the exposure machine used in this step, a direct drawing device, an exposure machine equipped with a metal halide lamp, etc. can be used. The pattern-shaped exposure mask is a negative mask.

As the active energy ray used for exposure, it is preferable to use laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm. By setting the maximum wavelength within this range, the photopolymerization initiator can be effectively activated. In addition, the amount of exposure varies depending on the film thickness, etc., but it can be set to, for example, 50 to 1500 mJ/cm ² .

[PEB step] "In this step, the resin layer is heated after exposure to harden the exposed portion. In this step, a photopolymerization initiator having a function as a photobase generator is used, or a resin layer (B) made of a combination of a photopolymerization initiator and a photobase generator is used in the exposure step The generated alkali can harden the resin layer (B) to the deep part. The heating temperature is, for example, 70 to 150°C. The heating time is, for example, 1 to 120 minutes. The curing of the resin composition in the present invention is, for example, the ring-opening reaction of the epoxy resin by thermal reaction, so it can suppress strain or curing shrinkage more than when curing is performed by light radical reaction.

[Development step] "In this step, the unexposed part is removed by alkali development, and a negative pattern-like insulating film (for example, a cover film) and a solder resist are formed." As the development method, a well-known method such as dipping can be used. In addition, as the developer, sodium carbonate, potassium carbonate, potassium hydroxide, amines, imidazoles such as 2-methylimidazole, alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution (TMAH), or these can be used Mixture.

[Post-curing step] "After the development step, the insulating film may be further irradiated with light, and heating may be performed, for example, at 150°C or higher. [Example]

Hereinafter, the present invention will be described in further detail based on examples and comparative examples, but the present invention is not limited by these examples and comparative examples.

(Synthesis Example 1) 　　 At room temperature, a four-necked 300 mL flask equipped with a nitrogen introduction tube, a thermometer, and a stirrer was fed with fat derived from a dimer acid with 36 carbon atoms as the dimer diamine (a) Diamine (manufactured by Croda Japan, product name PRIAMINE1075) 28.61g (0.052mol), 3,5-diaminobenzoic acid 4.26g (0.028mol) as carboxyl group-containing diamine (b), γ-butane 85.8 g of ester was dissolved.

Next, 30.12 g (0.152 mol) of cyclohexane-1,2,4-tricarboxylic acid anhydride (c) and 3.07 g (0.016 mol) of trimellitic anhydride (d) were fed, and kept at room temperature for 30 minutes. Furthermore, 30 g of toluene was fed and the temperature was raised to 160°C. After removing the water produced at the same time as the toluene, the solution was cooled to room temperature after being kept for 3 hours to obtain a solution containing the imide compound.

To the obtained solution containing the imide compound, 14.30 g (0.068 mol) of trimethylhexamethylene diisocyanate as the diisocyanate compound (e) was fed, and maintained at a temperature of 160°C for 32 hours , And diluted with 21.4 g of cyclohexanone to obtain a solution (A-1) containing a polyimide resin. The obtained polyamide imide resin had a mass average molecular weight Mw of 5250, a solid content of 41.5% by mass, an acid value of 63 mgKOH/g, and a content of the dimer diamine (a) of 40.0% by mass.

(Synthesis example 2) 　　 Into a four-necked 300 mL flask equipped with a nitrogen introduction tube, a thermometer, and a stirrer at room temperature, the fat derived from the dimer acid with 36 carbon atoms was fed as the dimer diamine (a) Diamine (manufactured by Croda Japan, product name PRIAMINE 1075) 29.49 g (0.054 mol), 3,5-diaminobenzoic acid 4.02 g (0.026 mol) as carboxyl group-containing diamine (b), γ-butane 73.5 g of ester was dissolved.

Next, 31.71 g (0.160 mol) of cyclohexane-1,2,4-tricarboxylic acid anhydride (c) and 1.54 g (0.008 mol) of trimellitic anhydride (d) were fed, and kept at room temperature for 30 minutes. Furthermore, 30 g of toluene was fed and the temperature was raised to 160°C. After removing the water produced at the same time as the toluene, the solution was cooled to room temperature after being kept for 3 hours to obtain a solution containing the imide compound.

To the obtained solution containing the imide compound, 6.90 g (0.033 mol) of trimethylhexamethylene diisocyanate as the diisocyanate compound (e) and 8.61 g (0.033 mol) of dicyclohexylmethane diisocyanate were fed. ), by keeping it at a temperature of 160°C for 32 hours, and diluting with 36.8 g of cyclohexanone to obtain a solution (A-2) containing a polyimide resin. The obtained polyamide imide resin had a mass average molecular weight Mw of 5840, a solid content of 40.4% by mass, an acid value of 62 mgKOH/g, and a content of the dimer diamine (a) of 40.1% by mass.

(Synthesis example 3) 　　 Into a four-necked 300 mL flask equipped with a nitrogen introduction tube, a thermometer, and a stirrer at room temperature, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane was fed 6.98 g, 3.80 g of 3,5-diaminobenzoic acid, 8.21 g of polyether diamine (manufactured by Huntsman, product name ELASTAMINE RT1000, molecular weight 1025.64), and 86.49 g of γ-butyrolactone were dissolved.

Next, 17.84 g of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride and 2.88 g of trimellitic anhydride were fed, and kept at room temperature for 30 minutes. Furthermore, 30 g of toluene was fed and the temperature was raised to 160° C., after removing the water produced at the same time as the toluene, it was kept for 3 hours and then cooled to room temperature to obtain an imide solution.

To the obtained imide solution, 9.61 g of trimellitic anhydride and 17.45 g of trimethylhexamethylene diisocyanate were fed, and kept at a temperature of 160° C. for 32 hours. In this manner, a carboxyl group-containing polyimide resin solution (A-3) was obtained. The solid content was 40.1% by mass, and the acid value was 83 mgKOH/g.

(Synthesis Example 4) 　　 To a liquid separation 3-necked flask equipped with a stirrer, a nitrogen introduction tube, a fractionating ring, and a cooling ring, 22.4 g of 3,3'-diamino-4,4'-dihydroxydiphenyl sulfide was added , 2,2'-bis[4-(4-aminophenoxy)phenyl]propane 8.2g, NMP30g, γ-butyrolactone 30g, 4,4'-oxydiphthalic anhydride 27.9g 3.8 g of trimellitic anhydride, stirred at 100 rpm for 4 hours in a nitrogen environment at room temperature. Next, 20 g of toluene was added, and the toluene and water were distilled off at a silicon bath temperature of 180° C. and 150 rpm, and the mixture was stirred for 4 hours to obtain a polyimide resin solution (PI-1) having a phenolic hydroxyl group and a carboxyl group. "The acid value of the resin (solid content) obtained" was 18 mgKOH, Mw was 10,000, and hydroxyl equivalent was 390.

(Examples 1-1 to 1-9 and Comparative Examples 1-1, 1-2) 　　 According to the component composition described in Table 1, Examples 1-1 to 1-9 and Comparative Examples 1-1, 1- were prepared respectively The materials described in 2 were premixed with a mixer, and then kneaded with a three-roll mill to prepare each resin composition for forming the resin layer. Unless otherwise specified, the value in the table is the mass part of the solid content.

<Formation of the resin layer> 　　 A flexible printed wiring substrate on which a circuit with a copper thickness of 18 μm was formed was prepared, and CZ-8100 from MEC was used for pretreatment. After that, the pre-treated flexible printed wiring substrate was coated with the methods described in Examples 1-1 to 1-9 and Comparative Examples 1-1 and 1-2 so that the film thickness after drying became 30 μm. Each resin composition obtained. After that, it was dried at 90° C. for 30 minutes in a hot-air circulating drying oven to form an uncured resin layer.

<Developability (alkali solubility)> The resin layer is formed as described above. For the uncured resin layer on each flexible printed wiring substrate, first use an exposure device equipped with a metal halide lamp (HMW-680- GW 20), at 300mJ / ² cm is formed at an opening of a diameter of 200μm, through a negative mask to pattern exposure. The board|substrate which has the resin layer after exposure was heat-processed at 90 degreeC for 30 minutes. After that, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30° C. and developed for 1 minute, the state of pattern formation was observed, and the developability (alkali solubility) was evaluated. The evaluation criteria are as follows. ○: The exposed portion exhibits development resistance, and the unexposed portion exhibits developability, so pattern formation is good. ×: Although the unexposed area exhibited developability, the analytical pattern was formed as poor (insufficient resolution).

<Heat resistance (solder heat resistance)> (Production of evaluation board) The resin layer is formed in the above-mentioned manner, and the uncured resin layer on each flexible printed wiring substrate is first exposed with a metal halide lamp. The device (HMW-680-GW20) uses a negative mask to perform pattern exposure through a negative mask with an opening of 200 μm in diameter ^{at 300 mJ/cm 2.} After that, the PEB step was carried out at 90°C for 30 minutes, followed by development (30°C, 0.2MPa, 1% by mass Na ₂ CO ₃ aqueous solution) for 60 seconds, and heat curing at 150°C for 60 minutes to produce the form A flexible printed wiring board (evaluation board) with a cured resin layer. (Evaluation method) The rosin-based flux was applied to the evaluation substrate prepared in the above-mentioned manner and immersed in a solder bath preset at 260°C for 20 seconds (10 seconds × 2 times) to observe the cured coating film ( The swelling and peeling of the resin layer) and evaluate the heat resistance (solder heat resistance). The evaluation criteria are as follows. ○: No swelling or peeling even after immersion for 10 seconds × 2 times. ×: When immersed for 10 seconds × once, swelling and peeling occurred.

<Chemical resistance (gold-plating resistance)> 　　 The same evaluation substrate as the aforementioned heat resistance evaluation was used, and the evaluation was carried out by the following method. For the evaluation substrate, use commercially available electroless nickel plating bath and electroless gold plating bath, apply 5μm nickel and 0.05μm gold plating at 80~90℃, observe the substrate and resin layer and evaluate the chemical resistance Resistance (gold-plated resistance). The evaluation criteria are as follows.　　○: No penetration between the substrate and the coating film (resin layer).　　△: Penetration is confirmed between the substrate and the coating film (resin layer).　　×: Peeling occurred in a part of the coating film (resin layer).

<Resilience (resilient/spring back)> (Production of test piece) Examples 1-1 to 1-9 and comparative examples were respectively coated on the polyimide film so that the film thickness after drying became 30μm The resin compositions obtained in 1-1 and 1-2 were dried in a hot-air circulating drying oven at 90°C for 30 minutes to form an uncured resin layer. After that, an exposure device (HMW-680-GW20) equipped with a metal halide lamp was used to perform exposure ^{at 300 mJ/cm 2 without passing through the mask.} After that, after a PEB step at 90°C for 30 minutes, development (30°C, 0.2MPa, 1% by mass Na ₂ CO ₃ aqueous solution) for 60 seconds, and thermal curing at 150°C for 60 minutes A test piece of a polyimide film formed with a cured resin layer was prepared. (Evaluation method) Cut the polyimide film test piece made in the above-mentioned manner into 2cm×7cm, and put the two ends of the long side together into a band-shaped loop, and use tape to bring the two ends together. Part of it is fixed on the electronic balance. When the ring is in a relaxed state, the ring is pressed by a glass plate and the measurement is performed so that the interval between the upper and lower sides of the ring becomes 3 mm, the load is used as the rebound force (g) to evaluate the resilience (resilience). The evaluation criteria are as follows. ○: Less than 30g. △: 30 g or more but less than 45 g. ×: 45 g or more.

<Warpage amount after curing> 　　 Use the same test piece as the above-mentioned evaluation of resilience, and evaluate by the following method. After cutting the test piece into 5cm×5cm, place the substrate on a horizontal test bench with the curved surface facing upwards. Use a ruler to measure the 4 locations from the test bench to the respective vertices in 1mm units. Set the maximum value of 4 parts as the amount of warpage, and evaluate the amount of warpage after hardening. The evaluation criteria are as follows.　　○: The amount of warpage is less than 3 mm.　　△: The amount of warpage is 3 mm or more but less than 6 mm.　　×: The amount of warpage is 6mm or more

The evaluation results are shown in Table 2.

(Examples 1-10 to 1-12) 　 　 According to the composition of the ingredients described in Table 3, the materials described in Examples 1-10 to 1-12 were prepared separately, premixed with a mixer, and then kneaded with a three-roll mill Thus, each resin composition for forming the resin layer (A) and each resin composition for forming the resin layer (B) are prepared. Unless otherwise specified, the value in the table is the mass part of the solid content.

<Formation of the resin layer (A)> 　　 A flexible printed wiring substrate on which a circuit with a copper thickness of 18 μm was formed was prepared, and CZ-8100 from MEC was used for pretreatment. After that, the pre-treated flexible printed wiring substrate was coated to form the resin layer (A) obtained in Examples 1-10 to 1-12 so that the film thickness after drying became 20 μm.的 each resin composition. After that, it was dried at 90° C. for 30 minutes in a hot-air circulation type drying oven to form a resin layer.

<Formation of the resin layer (B)> 　　 On the resin layer (A) formed above, the resins obtained in Examples 1-10 to 1-12 were respectively coated so that the film thickness after drying became 10 μm Each resin composition of layer (B). After that, it was dried at 90°C for 30 minutes in a hot-air circulation type drying oven to form a resin layer (B).

In this manner, an uncured laminate structure composed of the resin layer (A) and the resin layer (B) described in Examples 1-10 to 1-12 was formed on the flexible printed wiring substrate .

For the uncured laminate structure formed in the above-mentioned manner, the same method was used to implement the uncured resin in Examples 1-1 to 1-9 and Comparative Examples 1-1 and 1-2. The evaluation performed by the layer.　　 These evaluation results are shown in Table 4.

From the evaluation results shown in Tables 2 and 4, it can be confirmed and understood that the resin composition system of each example can obtain excellent developability or heat resistance, low rebound properties, and low warpage after heating.

(Examples 2-1 to 2-5 and Comparative Examples 2-1, 2-2) 　　 According to the component composition described in Table 5, Examples 2-1 to 2-5 and Comparative Examples 2-1, 2- were prepared respectively The materials described in 2 are premixed with a stirrer, and then kneaded with a three-roll mill to prepare a resin composition for forming each resin layer. Unless otherwise specified, the value in the table is the mass part of the solid content.

<Formation of resin layer (A)> 　　 A flexible printed wiring substrate on which a circuit with a copper thickness of 18 μm was formed was prepared, and CZ-8100 from MEC was used for pretreatment. After that, the pre-treated flexible printed wiring substrate was coated so that the film thickness after drying became 25 μm to constitute Examples 2-1 to 2-4 and Comparative Examples 2-1, 2-2. The obtained resin composition of each resin layer (A). After that, it was dried in a hot-air circulation type drying oven at 90°C for 30 minutes to form a resin layer (A).

<Formation of the resin layer (B)> 　　 On the resin layer (A) formed above, coating was applied so that the film thickness after drying became 10 μm to constitute Examples 2-1 to 2-4 and Comparative Example 2-1. , 2-2 Resin composition of each resin layer (B) obtained. After that, it was dried at 90°C for 30 minutes in a hot-air circulation type drying oven to form a resin layer (B).

In this way, the resin layer (A) and the resin layer (B) described in Examples 2-1 to 2-4 and Comparative Examples 2-1 and 2-2 were formed on the flexible printed wiring substrate The unhardened layered structure.

<Developability (alkali solubility)> The laminated structure is formed as described above. For the uncured laminated structure on each flexible printed wiring substrate, first use an exposure device equipped with a metal halide lamp ( HMW-680-GW20), the pattern exposure is performed through a negative mask by forming an opening with a diameter of 200μm ^{at 500mJ/cm 2.} The substrate having the unhardened laminated structure after exposure was heat-treated at 90°C for 30 minutes. After that, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30° C. and developed for 1 minute to evaluate whether a 200 μm opening pattern can be formed. The evaluation criteria are as follows. ○: The exposed portion exhibits development resistance, and the unexposed portion exhibits developability, so pattern formation is good. △: Although the unexposed area exhibited developability, the exposed area had insufficient developability, so that the pattern could not be formed. ×: Since the unexposed part cannot be dissolved in the developing solution, the pattern cannot be formed.

<Heat resistance> The laminated structure is formed as described above. For the uncured laminated structure on each flexible printed wiring substrate, first use an exposure device equipped with a metal halide lamp (HMW-680-GW20 ), to form an opening with a diameter of 200 μm at 500 mJ/cm ² , and perform pattern exposure through a negative mask. After that, after the PEB step at 90°C for 30 minutes, development (30°C, 0.2MPa, 1% by mass Na ₂ CO ₃ aqueous solution) for 60 seconds, and thermal curing at 150°C × 60 minutes to produce A flexible printed wiring board (evaluation board) on which a hardened laminated structure is formed. The rosin-based flux was applied to the evaluation board and immersed in a solder bath preset at 260°C for 20 seconds (10 seconds × 2 times), and the expansion and peeling of the cured coating film were evaluated. The evaluation criteria are as follows. ○: No swelling or peeling even after immersion for 10 seconds × 2 times. ×: When immersed for 10 seconds × once, swelling and peeling occurred, so the adhesiveness was insufficient.

<Flexibility (flexibility test after solder reflow at 260°C)> 　　 The above evaluation board is passed through a reflow oven set to a maximum of 260°C for 3 times to obtain a test piece, and the test piece is bent by the following test method Evaluation of foldability. The test piece is clamped by two flat plates and bent at 180° with the cured coating film on the outside, and a load of load G (standard weight of 1 kg) is applied for 10 seconds to bend the sheet metal. After that, an optical microscope was used to confirm whether there were cracks in the cured coating film portion of the bent portion, and the operation so far was set to 1 cycle, and the number of times until cracks occurred was recorded. The evaluation criteria are as follows.　　◎: Bending more than 20 times.　　○: Bend more than 10 times but less than 20 times.　　△: Bend more than 5 times but less than 10 times.　　×: The bend is less than 5 times.

The evaluation results are shown in Table 6.

From the evaluation results shown in the above table, it can be confirmed and understood that, in addition to excellent developability and heat resistance, the laminated structure of each example can obtain good flexibility even after solder reflow.

Next, for the resin composition constituting the resin layer (B) of the above-mentioned Example 2-5, the above-mentioned resin layer (B) was used and formed on a flexible printed wiring substrate on which a circuit with a copper thickness of 18 μm was formed. The coating film is formed in the same way. For the obtained coating film, the above-mentioned resolution, heat resistance, and flexibility were evaluated. The evaluation results are shown in Table 7.

1‧‧‧Flexible printed wiring substrate 2‧‧‧Conductor circuit 3‧‧‧Resin layer 4‧‧‧Resin layer 5‧‧‧Mask

[Fig. 1] Fig. 1 is a schematic diagram showing the steps of a manufacturing method of a flexible printed wiring board shown as an example of the electronic component of the present invention.　　 [FIG. 2] A schematic diagram showing another example of the manufacturing method of the flexible printed wiring board shown as an example of the electronic component of the present invention.

Claims (8)

A curable resin composition comprising an alkali-soluble polyimide resin, an alkali-soluble resin other than the polyimide resin, and a curable resin composition of a curable compound, which is characterized by the aforementioned polyimide resin Alkali-soluble resins other than amine resins are polyamide resins having a structure represented by the following general formula (1) and a structure represented by the following general formula (2), the aforementioned polyamide resin The blending ratio with the aforementioned polyimide resin is 98:2~80:20 according to the mass ratio,

(X ₁ is a residue of aliphatic diamine (a) derived from a dimer acid with a carbon number of 24 to 48, X ₂ is a residue of an aromatic diamine (b) having a carboxyl group, and Y is each independently a ring Hexane ring or aromatic ring). The curable resin composition of claim 1, which further contains core-shell rubber particles. The curable resin composition according to claim 1, wherein the polyimide resin has a carboxyl group. The curable resin composition of claim 1, wherein the polyimide resin has a carboxyl group and a phenolic hydroxyl group. The curable resin composition of claim 1, wherein the curable compound is an epoxy resin. A laminated structure having a resin layer (A) and a resin layer (B) laminated on a substrate through the resin layer (A), characterized in that the aforementioned resin layer (B) is composed of: It is made of the curable resin composition of any one of claims 1 to 5, and the aforementioned resin layer (A) is made of an alkali-developable resin composition containing an alkali-soluble resin and a heat-reactive compound. A hardened product characterized by the hardenable resin composition of any one of claims 1 to 5 or the laminated structure of claim 6. An electronic component characterized by having an insulating film made of a hardened material as claimed in Claim 7.

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