JP6869078B2 - Curable resin compositions, laminated structures, cured products thereof, and electronic components - Google Patents

Description

The present invention relates to a curable resin composition (hereinafter, also simply referred to as “composition”) useful as an insulating film for electronic components such as flexible printed wiring boards, a laminated structure, a cured product thereof, and electronic components.

In recent years, with the spread of smartphones and tablet terminals, electronic devices have become smaller and thinner, and it has become necessary to reduce the space for electronic components such as circuit boards. Therefore, the applications of flexible printed wiring boards that can be folded and stored have expanded, and flexible printed wiring boards that have higher reliability than ever before are required.

On the other hand, at present, as an insulating film for ensuring the insulation reliability of the flexible printed wiring board, the bent part (bent part) is covered with a polyimide-based material having excellent mechanical properties such as heat resistance and flexibility. A mixed loading process using a ray (see, for example, Patent Documents 1 and 2) and a photosensitive resin composition having excellent electrical insulation and solder heat resistance and capable of fine processing is used for the mounting portion (non-bent portion). Widely adopted.

That is, the polyimide-based coverlay is not suitable for fine wiring because it requires processing by die punching. Therefore, it is necessary to partially use an alkali-developed photosensitive resin composition (solder resist) that can be processed by photolithography in the chip mounting portion that requires fine wiring.

Japanese Unexamined Patent Publication No. 62-263692 Japanese Unexamined Patent Publication No. 63-11024

As described above, in the conventional manufacturing process of the flexible printed wiring board, there is no choice but to adopt a mixed loading process of the process of laminating the coverlay and the process of forming the solder resist, which has a problem of inferior cost and workability. It was.

On the other hand, it has been studied to apply an insulating film as a solder resist or an insulating film as a coverlay as a solder resist and a coverlay of a flexible printed wiring board, but the space of the circuit board is reduced. A material that can sufficiently satisfy the required performance of both the solder resist and the coverlay has not yet been put into practical use.

In addition, solder resist and coverlay have excellent developability (alkali solubility), heat resistance (solder heat resistance), low resilience (springback property), and small warpage after heating (warp after curing). , Various characteristics are required. However, if an alkali-soluble resin having a large molecular weight is used in order to improve low resilience and warpage after heating while ensuring heat resistance, there arises a problem that development cannot be performed. Further, although the imide resin has heat resistance, it has a drawback that the warp after curing is large, and the urethane resin has a problem that the heat resistance is poor although it has low resilience and low warpage. Therefore, the conventionally proposed compositions using various resins cannot satisfy all the requirements that the composition is excellent in heat resistance and low resilience without impairing the developability and that the warp after heating is small. ..

Therefore, a main object of the present invention is to provide a curable resin composition that satisfies the required performances of both solder resist and coverlay, is excellent in heat resistance and low resilience without impairing developability, and has little warpage after heating. There is.
Another object of the present invention is an insulating film such as a flexible printed wiring board, particularly a curable resin composition suitable for a batch forming process of a bent portion (bent portion) and a mounting portion (non-bent portion), and a laminated structure. It is an object of the present invention to provide an electronic component such as a body, a cured product thereof, and a flexible printed wiring board having the cured product as a protective layer such as a coverlay or a solder resist.

As a result of diligent studies to solve the above problems, the present inventors have completed the present invention having the following contents as a gist.
That is, the curable resin composition of the present invention is characterized by containing an alkali-soluble polyamide-imide resin, an alkali-soluble polyimide resin, and a curable compound.

（Ｘ_１は炭素数が２４〜４８のダイマー酸由来の脂肪族ジアミン（ａ）の残基、Ｘ_２はカルボキシル基を有する芳香族ジアミン（ｂ）の残基、Ｙはそれぞれ独立にシクロヘキサン環または芳香環である。） In the curable resin composition of the present invention, the alkali-soluble polyamide-imide resin is a polyamide-imide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2). Is preferable.

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

Further, in the curable resin composition of the present invention, the alkali-soluble polyimide resin is preferably a polyimide resin having a carboxyl group, and the alkali-soluble polyimide resin has a carboxyl group and a phenolic hydroxyl group. It is more preferable that the polyimide resin has.

Further, in the curable resin composition of the present invention, it is preferable that the curable compound is an epoxy resin.

Further, the laminated structure of the present invention is a laminated structure having a resin layer (A) and a resin layer (B) laminated on a base material via the resin layer (A).
The resin layer (B) is made of the curable resin composition, and the resin layer (A) is made of an alkali-developable resin composition containing an alkali-soluble resin and a heat-reactive compound. To do.

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

Further, the electronic component of the present invention is characterized by having an insulating film made of the cured product.

Here, as the electronic component of the present invention, for example, an insulating film formed by forming a layer of the laminated structure on a flexible printed wiring board, patterning by light irradiation, and collectively forming a pattern with a developing solution. Those having Further, without using the laminated structure, the resin layer (A) and the resin layer (B) are sequentially formed on the flexible printed wiring board, then patterned by light irradiation, and the patterns are batched with a developing solution. It may have an insulating film formed by the above. In the present invention, the "pattern" means a cured product in the form of a pattern, that is, an insulating film.

According to the present invention, it is possible to provide a curable resin composition that satisfies the required performances of both solder resist and coverlay, is excellent in heat resistance and low resilience without impairing developability, and has little warpage after heating. it can. In addition, an insulating film for electronic components such as flexible printed wiring boards, particularly a curable resin composition suitable for a batch forming process of a bent portion (bent portion) and a mounting portion (non-bent portion), a laminated structure, and its curing. It has become possible to realize an electronic component such as a flexible printed wiring board having a product and a cured product thereof as a protective film such as a coverlay or a solder resist.

It is a process drawing which shows typically the manufacturing method of the flexible printed wiring board which shows an example of the electronic component of this invention. It is a process drawing which shows another example of the manufacturing method of the flexible printed wiring board which shows an example of the electronic component of this invention schematically.

Hereinafter, embodiments of the present invention will be described in detail.
(Curable resin composition)
The curable resin composition of the present invention contains an alkali-soluble polyamide-imide resin, an alkali-soluble polyimide resin, and a curable compound.
By using the alkali-soluble polyamide-imide resin and the alkali-soluble polyimide resin in combination, a curable resin having excellent heat resistance and low resilience without impairing developability and having little warpage after heating. The composition can be realized.

In the curable resin composition of the present invention, the mixing ratio of the polyamide-imide resin and the polyimide resin can be 98: 2 to 50:50 in terms of mass ratio, and 90: 10 to 50:50. It is preferable to do so.

(Alkali-soluble polyamide-imide resin)
In the curable resin composition of the present invention, the alkali-soluble polyamide-imide resin may be any as long as it contains one or more functional groups of phenolic hydroxyl groups and carboxyl groups and can be developed with an alkaline solution. Known and commonly used ones are used.
Such an alkali-soluble polyamide-imide resin is, for example, a resin obtained by reacting a carboxylic acid anhydride component with an amine component to obtain an imidized product, and then reacting the obtained imidized product with an isocyanate component. And so on. Here, the alkali-soluble group is introduced by using an amine component having a carboxyl group or a phenolic hydroxyl group. Further, the imidization may be carried out by thermal imidization or chemical imidization, or may be carried out in combination thereof.

Examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydride and tricarboxylic acid anhydride, but the present invention is not limited to these acid anhydrides, and acid anhydride groups that react with amino groups and isocyanate groups and acid anhydride groups and Any compound having a carboxyl group can be used including its derivative. Moreover, these carboxylic acid anhydride components may be used alone or in combination.

As the amine component, diamines such as aliphatic diamines and aromatic diamines, polyvalent amines such as aliphatic polyether amines, diamines having a carboxyl group, 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 capable of introducing at least one functional group out of a phenolic hydroxyl group and a carboxyl group. Moreover, these amine components may be used alone or in combination.

As the isocyanate component, aromatic diisocyanates and their isomers and multimers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers and other diisocyanates and other general-purpose diisocyanates can be used. It is not limited. Moreover, these isocyanate components may be used alone or in combination.

The alkali-soluble polyamide-imide resin as described above has a good balance between the alkali solubility (developability) of the polyamide-imide resin and other properties such as the mechanical properties of the cured product of the resin composition containing the polyamide-imide resin. The acid value (solid content acid value) is preferably 30 mgKOH / g or more, more preferably 30 mgKOH / g to 150 mgKOH / g, and 50 mgKOH / g to 120 mgKOH / g. Is particularly preferable. Specifically, by setting this acid value to 30 mgKOH / g or more, alkali solubility, that is, developability is improved, and further, the crosslink density with the thermosetting component after light irradiation is increased, so that sufficient development is possible. Contrast can be obtained. Further, by setting the acid value to 150 mgKOH / g or less, so-called heat fogging in the PEB (POST EXPOSURE BAKE) step after light irradiation, which will be described later, can be suppressed, and the process margin becomes large.
The molecular weight of the alkali-soluble polyamide-imide resin is preferably 20,000 or less, more preferably 1,000 to 15,000, in consideration of developability and cured coating film characteristics. More preferably, it is between 2,000 and 10,000. When the molecular weight is 20,000 or less, the alkali solubility of the unexposed portion is increased, and the developability is improved. On the other hand, when the molecular weight is 1,000 or more, sufficient development resistance and cured physical properties can be obtained in the exposed portion after the exposure / PEB step.
In particular, in the present invention, it is more preferable to use a polyamide-imide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2) in terms of further improving developability.

Here, X ₁ is a residue of an aliphatic diamine (a) derived from dimer acid having 24 to 48 carbon atoms (also referred to as “dimer diamine (a)” in the present specification). X ₂ is a residue of an aromatic diamine (b) having a carboxyl group (also referred to as “carboxyl group-containing diamine (b)” in the present specification). Y is each independently cyclohexane or aromatic ring.

By including the structure represented by the general formula (1) and the structure represented by the general formula (2), a mild alkaline solution such as a 1.0% by mass aqueous sodium carbonate solution is used. It can be a polyamide-imide resin having excellent alkali solubility, which can also be dissolved. Further, the cured product of the resin composition containing such a polyamide-imide resin can have excellent dielectric properties.

Dimerdiamine (a) can be obtained by reductive amination of the carboxyl group in the dimer of an aliphatic unsaturated carboxylic acid having 12 to 24 carbon atoms. That is, dimerdiamine (a), which is an aliphatic diamine derived from dimer acid, can be obtained by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid to obtain dimer acid, reducing the diamine, and then aminating the diamine. .. As such an aliphatic diamine, for example, a commercially available product such as PRIAMINE1073, 1074, 1075 (manufactured by Croda Japan, trade name), which is a diamine having a skeleton having 36 carbon atoms, can be used. The diamine diamine (a) may be preferably derived from a diamine acid having 28 to 44 carbon atoms, and more preferably derived from a dimer acid having 32 to 40 carbon atoms.

Specific examples of the carboxyl group-containing diamine (b) include 3,5-diaminobenzoic acid, 3,4-diaminobenzoic acid, 5,5'-methylenebis (anthranilic acid), benzidine-3,3'-dicarboxylic acid and the like. Can be mentioned. The carboxyl group-containing diamine (b) may be composed of one kind of compound or may be composed of a plurality of kinds of compounds. From the viewpoint of raw material availability, the carboxyl group-containing diamine (b) preferably contains 3,5-diaminobenzoic acid and 5,5'-methylenebis (anthranilic acid).

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) in the polyamide-imide resin is not limited. The content of the diamine diamine (a) (unit: mass%) from the viewpoint of improving the balance between the alkali solubility of the polyamide-imide resin and other properties such as the mechanical properties of the cured product of the resin composition containing the polyamide-imide resin. ) Is preferably 20 to 60% by mass, more preferably 30 to 50% by mass. In the present specification, the "content of dimer diamine (a)" refers to the amount of diamine diamine (a) charged as one of the raw materials for producing the polyamide-imide resin of the produced polyamide-imide resin. It means the ratio to the mass. Here, "the mass of the produced polyamide-imide resin", from the charged amounts of all the raw material for producing the polyamide-imide resin, resulting in imidization water (H 2 _O) and carbon dioxide produced by amidation (CO It is the value obtained by subtracting the theoretical amount of _2).

From the viewpoint of increasing the alkali solubility of the polyamide-imide resin, the portion represented by Y in the general formula (1) and the general formula (2) preferably has a cyclohexane ring. From the viewpoint of improving the balance between the alkali solubility of the polyamide-imide resin and other properties such as the mechanical properties of the cured product of the resin composition containing the polyamide-imide resin, the aromatic ring and the cyclohexane ring in the portion indicated by Y above. In terms of the quantitative relationship with, the molar ratio of the cyclohexane ring content to the aromatic ring content is preferably 85/15 to 100/0, more preferably 90/10 to 99/1. It is more preferably 90/10 to 98/2.

ここで、Ｘ_３は、ダイマージアミン（ａ）およびカルボキシル基含有ジアミン（ｂ）以外のジアミン（ｆ）（本明細書において、「他のジアミン（ｆ）」ともいう。）の残基であり、Ｙは、上記一般式（１）および上記一般式（２）と同様に、それぞれ独立に芳香環またはシクロヘキサン環である。他のジアミン（ｆ）は１種類の化合物から構成されていてもよいし、複数種類の化合物から構成されていてもよい。 The polyamide-imide resin may further have a partial structure represented by the following general formula (i).

Here, X ₃ is a residue of a diamine (f) other than the diamine diamine (a) and the carboxyl group-containing diamine (b) (also referred to as “another diamine (f)” in the present specification). Like the general formula (1) and the general formula (2), Y is independently an aromatic ring or a cyclohexane ring, respectively. The other diamine (f) may be composed of one kind of compound or may be composed of a plurality of kinds of compounds.

Specific examples of other amines (f) include 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, and bis [4- (4). -Aminophenoxy) phenyl] sulfone, 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'-dihydroxybiphenyl-4,4' -Diamine, (4,4'-diamino) diphenyl ether, (4,4'-diamino) diphenylsulfone, (4,4'-diamino) benzophenone, (3,3'-diamino) benzophenone, (4,4'- Aromatic diamines such as diamino) diphenylmethane, (4,4'-diamino) diphenyl ether, and (3,3'-diamino) diphenyl ether include hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, octadeca. Examples thereof include aliphatic diamines such as methylene diamine, 4,4'-methylenebis (cyclohexylamine), isophorone diamine, 1,4-cyclohexanediamine and norbornene diamine.

The polyamide-imide resin may have a structure represented by the following general formula (ii).

Here, Z may be an aliphatic group or a group containing an aromatic. When it is an aliphatic group, it may contain an alicyclic group such as a cyclohexane ring. According to the production method described later, Z is a residue of the diisocyanate compound (e).

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

In the imidization step, from dimerdiamine (a), carboxyl group-containing diamine (b), and cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) and trimellitic anhydride (d). One or two selected from the above group is reacted to obtain an imidized product.

The amount of the diamine diamine (a) charged is preferably an amount in which the content of the diamine diamine (a) is 20 to 60% by mass, and more preferably an amount in which the content of the diamine diamine (a) is 30 to 50% by mass. .. The definition of the content of diamine diamine (a) is as described above.

If necessary, other diamines (f) may be used together with the diamine diamine (a) and the carboxyl group-containing diamine (b).

From the viewpoint of increasing the alkali solubility of the polyamide-imide resin, it is preferable to use cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) in the imidization step. The molar ratio of the amount of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) used to the amount of trimellitic anhydride (d) used shall be 85/15 to 100/0. Is preferable, 90/10 to 99/1 is more preferable, and 90/10 to 98/2 is even more preferable.

With the amount of the diamine compound used to obtain the imidized product (specifically, it means the diamine diamine (a) and the carboxyl group-containing diamine (b) and other diamines (f) used as needed). One or two selected from the group consisting of acid anhydrides (specifically, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydrous (c) and trimellitic anhydride (d)). Meaning.) The relationship with the quantity is not limited. The amount of the acid anhydride used is preferably such that the molar ratio to the amount of the diamine compound used is 2.0 or more and 2.4 or less, and the molar ratio is 2.0 or more and 2.2 or less. More preferably.

In the amidimidization step, the diisocyanate compound (e) is reacted with the imidized product obtained in the above imidization step to obtain a polyamide-imide resin containing a substance having a structure represented by the following general formula (3).

The specific type of the diisocyanate compound (e) is not limited. The diisocyanate compound (e) may be composed of one kind of compound or may be composed of a plurality of kinds of compounds.

Specific examples of the diisocyanate compound (e) include 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m. Aromatic diisocyanates such as -xylylene diisocyanate and 2,4-tolyrene dimer; and aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate and norbornene diisocyanate can be mentioned. From the viewpoint of improving both the alkali solubility of the polyamide-imide resin and the light transmittance of the polyamide-imide resin, the diisocyanate compound (e) preferably contains an aliphatic isocyanate, and the diisocyanate compound (e) is an aliphatic isocyanate. Is more preferable.

The amount of the diisocyanate compound (e) used in the amidimidization step is not limited. From the viewpoint of imparting appropriate alkali solubility to the polyamide-imide resin, the amount of the diisocyanate compound (e) used is 0.3 or more and 1.0 or less as a molar ratio to the amount of the diamine compound used to obtain the imide compound. It is preferably 0.4 or more and 0.95 or less, and more preferably 0.50 or more and 0.90 or less.

The polyamide-imide resin produced in this manner contains a substance having a structure represented by the following general formula (3).

In the above general formula (3), X is an independently diamine residue (diamine compound residue), Y is an independently aromatic ring or cyclohexane ring, and Z is a diisocyanate compound residue. n is a natural number.

(Alkali-soluble polyimide resin)
As the alkali-soluble polyimide resin, any known and commonly used one may be used 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.

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

Examples of such an alkali-soluble polyimide resin include a resin obtained by reacting a carboxylic acid 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. Further, the imidization may be carried out by thermal imidization or chemical imidization, or may be carried out in combination thereof.

Examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydride and tricarboxylic acid anhydride, but the present invention is not limited to these acid anhydrides, and acid anhydride groups that react with amino groups and isocyanate groups and acid anhydride groups and Any compound having a carboxyl group can be used including its derivative. Moreover, these carboxylic acid anhydride components may be used alone or in combination.

As the amine component, diamines such as aliphatic diamines and aromatic diamines, polyvalent amines such as aliphatic polyether amines, diamines having a carboxyl group, 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 capable of introducing at least one functional group out of a phenolic hydroxyl group and a carboxyl group. Moreover, these amine components may be used alone or in combination.

As the isocyanate component, aromatic diisocyanates and their isomers and multimers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers and other diisocyanates and other general-purpose diisocyanates can be used. It is not limited. Moreover, these isocyanate components may be used alone or in combination.

In the synthesis of such an alkali-soluble polyimide resin, a known and commonly used organic solvent can be used. As such an organic solvent, there is no problem as long as it is a solvent that does not react with carboxylic acid anhydrides, amines and isocyanates as raw materials and in which these raw materials are dissolved, and the structure thereof is not particularly limited. In particular, aprotic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and γ-butyrolactone are preferable because of the high solubility of the raw material.

The alkali-soluble polyimide resin as described above has a good balance between the alkali-solubleness (developability) of the polyimide resin and other properties such as the mechanical properties of the cured product of the resin composition containing the polyimide resin. Therefore, the acid value (solid content acid value) is preferably 20 to 200 mgKOH / g, and more preferably 60 to 150 mgKOH / g. Specifically, by setting this acid value to 20 mgKOH / g or more, alkali solubility, that is, developability is improved, and further, the crosslink density with the thermosetting component after light irradiation is increased, so that sufficient development is possible. Contrast can be obtained. Further, by setting the acid value to 200 mgKOH / g or less, so-called heat fogging in the PEB (POST EXPOSURE BAKE) step after light irradiation, which will be described later, can be suppressed, and the process margin becomes large.

Further, the molecular weight of such an alkali-soluble polyimide resin is preferably 100,000 or less, and more preferably 1,000 to 100,000, in consideration of developability and cured coating film characteristics. It is preferable, and more preferably 2,000 to 50,000. When this molecular weight is 100,000 or less, the alkali solubility of the unexposed portion is increased, and the developability is improved. On the other hand, when the molecular weight is 1,000 or more, sufficient development resistance and cured physical properties can be obtained in the exposed portion after the exposure / PEB step.

(Curable compound)
The curable resin composition of the present invention further contains a curable compound. As the curable compound, a known and commonly used compound having a functional group capable of a curing reaction by heat or light is used. Examples thereof include a thermosetting compound having a functional group capable of a curing reaction by heat such as a cyclic (thio) ether group, and a photocurable compound capable of a curing reaction by light such as an ethylenically unsaturated double bond group. Of these, it is preferable to use a thermosetting compound, particularly an epoxy resin.
Examples of this epoxy resin include bisphenol A type epoxy resin, brominated epoxy resin, novolak type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidylamine type epoxy resin, hidden in type epoxy resin, and alicyclic type. Epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenel type or biphenol type epoxy resin or a mixture thereof; bisphenol S type epoxy resin, bisphenol A novolac type epoxy resin, heterocyclic epoxy resin, biphenyl novolac type epoxy resin, naphthalene Examples thereof include a group-containing epoxy resin and an epoxy resin having a dicyclopentadiene skeleton.

In particular, when a thermosetting compound is used, the thermosetting compound has an equivalent ratio to an alkali-soluble resin (polyamidoimide resin, polyimide resin) (alkali-soluble group such as carboxyl group: thermosetting such as epoxy group). The group) is preferably blended in a ratio of 1: 0.1 to 1:10. With such a blending ratio, development becomes good and a fine pattern can be easily formed. The equivalent ratio is more preferably 1: 0.2 to 1: 5.

(Photopolymerization initiator)
When the curable resin composition of the present invention is a photosensitive resin composition, it is preferable that the curable resin composition further contains a photopolymerization initiator. As the photopolymerization initiator, known and commonly used ones can be used, and 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. It is preferable to use a photopolymerization initiator that also has a function. In this PEB step, a photopolymerization initiator and a photobase generator may be used in combination.

The photopolymerization initiator, which also has a function as a photobase generator, is a thermocurable compound which is a curable compound when the molecular structure is changed by irradiation with light such as ultraviolet rays or visible light or when the molecule is cleaved. A compound that produces one or more basic substances that can function as a catalyst for a polymerization reaction. Examples of the basic substance include secondary amines and tertiary amines.
Examples of the photopolymerization initiator having a function as such a photobase generator include an α-aminoacetophenone compound, an oxime ester compound, an acyloxyimino group, an N-formylated aromatic amino group, and an N-acylated aromatic. Examples thereof include compounds having a substituent such as a group amino group, a nitrobenzyl carbamate group and an alcoholoxybenzyl carbamate group. Of these, an oxime ester compound and an α-aminoacetophenone compound are preferable, and an oxime ester compound is more preferable. As the α-aminoacetophenone compound, those having two or more nitrogen atoms are particularly preferable.

The α-aminoacetophenone compound may have a benzoin ether bond in the molecule, and when irradiated with light, cleavage occurs in the molecule to generate a basic substance (amine) that acts as a curing catalyst.

As the oxime ester compound, any compound that produces a basic substance by light irradiation can be used.

Such a photopolymerization initiator may be used alone or in combination of two or more. The blending amount of the photopolymerization initiator in the resin composition is preferably 0.1 to 40 parts by mass with respect to 100 parts by mass of the total amount of the above-mentioned polyamide-imide resin and polyimide resin, and more preferably 0.3 to 15 parts by mass. It is a mass part. When the amount is 0.1 parts by mass or more, the contrast of development resistance of the light-irradiated portion / unirradiated portion can be obtained satisfactorily. Further, when the amount is 40 parts by mass or less, the characteristics of the cured product are improved.

The curable resin composition of the present invention may further contain the following components, if necessary.

(Polymer resin)
In the curable resin composition of the present invention, a known and commonly used polymer resin can be blended for the purpose of improving the flexibility and the dryness to the touch of the obtained cured product. Examples of such polymer resins include cellulose-based, polyester-based, phenoxy resin-based polymers, polyvinyl acetal-based, polyvinyl butyral-based, polyamide-based polymers, and elastomers. One type of such a polymer resin may be used alone, 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 blended in order to suppress curing shrinkage of the cured product and improve properties such as adhesion and hardness. Examples of such inorganic fillers include barium sulfate, amorphous silica, molten silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, and boron nitride. Neuburg Siricious Earth and the like can be mentioned.

(Colorant)
The curable resin composition of the present invention can be blended with known and commonly used colorants such as red, orange, blue, green, yellow, white and black. The colorant may be any of pigments, dyes and pigments.

(Organic solvent)
The curable resin composition of the present invention can contain an organic solvent for preparing the resin composition and for adjusting the viscosity for coating on a base material or a carrier film. Examples of such an organic solvent include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents and the like. Such an organic solvent may be used alone or as a mixture of two or more.

(Other ingredients)
The curable resin composition of the present invention may further contain components such as a mercapto compound, an adhesion accelerator, an antioxidant, and an ultraviolet absorber, if necessary. As these, known and commonly used ones can be used.
In addition, known and commonly used thickeners such as fine silica, hydrotalcite, organic bentonite, and montmorillonite, antifoaming agents such as silicone-based, fluorine-based, and polymer-based and / or leveling agents, silane coupling agents, and rust preventives. Known and commonly used additives such as, etc. can be blended.

(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 via 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. In the laminated structure of the present invention, the resin layer (B) is made of the above-mentioned curable resin composition, and the resin layer (A) is made of an alkali-developable resin composition containing an alkali-soluble resin and a heat-reactive compound. It is characterized by the fact that

In the present invention, the resin layer (B) on the upper layer side of the laminated structure in which the two resin layers are laminated is made of the curable resin composition of the present invention, thereby impairing the developability. It has excellent heat resistance and low resilience, and it is possible to reduce the warpage after heating.

[Resin layer (A)]
(Alkaline developing type resin composition)
The alkali-developable resin composition constituting the resin layer (A) may be any resin composition that can be developed with an alkali solution containing an alkali-soluble resin and a heat-reactive compound. Preferred examples of the alkali-soluble resin include a compound having a phenolic hydroxyl group, a compound having a carboxyl group, and a resin composition containing a compound having a phenolic hydroxyl group and a carboxyl group, and known and commonly used ones are 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 have been conventionally used as solder resist compositions, can be mentioned.

Here, a known and commonly used compound is used as the carboxyl group-containing resin or the carboxyl group-containing photosensitive resin, and the compound having an ethylenically unsaturated bond, and the cyclic (thio) ether is used as the heat-reactive compound. A known and commonly used compound having a functional group capable of a curing reaction by heat such as a group is used.

Such a resin layer (A) may or may not contain a photopolymerization initiator, but the photopolymerization initiator used when the photopolymerization initiator is contained is the curing of the present invention. Examples thereof include the same photopolymerization initiators used in the sex resin composition.

In addition, the resin layer (A) can contain other components similar to those of the curable resin composition of the present invention, such as a polymer resin, an inorganic filler, a colorant, and an organic solvent.

[Resin layer (B)]
The resin layer (B) is formed by the curable resin composition of the present invention described above, and is not particularly limited in other respects.

Since the laminated structure of the present invention is excellent in flexibility, it can be used for at least one of a bent portion and a non-bent portion of an electronic component such as a flexible printed wiring board. For example, a flexible printed wiring board. It can be used for at least one of a coverlay, a solder resist and an interlayer insulating material.

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

(Dry film)
The dry film can be produced, for example, as follows.
That is, first, on the carrier film (support film), the curable resin composition constituting the resin layer (B) and the alkali-developable resin composition constituting the resin layer (A) are each diluted with an organic solvent. The viscosity is adjusted to an appropriate level, and the resin is sequentially applied by a known method such as a comma coater according to a conventional method. Then, usually, by drying at a temperature of 50 to 130 ° C. for 1 to 30 minutes, a dry film in which a coating film of the resin layer (B) and the resin layer (A) is formed on the carrier film can be produced. A peelable cover film (protective film) can be further laminated on the dry film for the purpose of preventing dust from adhering to the surface of the coating film. As the carrier film and the cover film, a conventionally known plastic film can be appropriately used, and the cover film may be smaller than the adhesive force between the resin layer and the carrier film when the cover film is peeled off. preferable. The thickness of the carrier film and the cover film is not particularly limited, but is generally selected as appropriate in the range of 10 to 150 μm.

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

(Electronic components)
The curable resin composition and the laminated structure of the present invention as described above can be effectively used for electronic components such as flexible printed wiring boards. Specifically, the curing of the insulating film formed by forming a layer of the curable resin composition or the laminated structure of the present invention on a flexible printed wiring board, patterning by light irradiation, and forming a pattern with a developing solution. Examples include a flexible printed wiring board having an object.
Hereinafter, a method for manufacturing a flexible printed wiring board will be specifically described.

(Manufacturing method of flexible printed wiring board)
The flexible printed wiring board using the laminated structure of the present invention can be manufactured, for example, according to the procedure shown in the process diagram of FIG. That is, a step of forming a layer of the laminated structure of the present invention on a flexible printed wiring base material on which a conductor circuit is formed (lamination step), and a step of irradiating the layer of the laminated structure with active energy rays in a pattern (exposure). A manufacturing method including a step (step) and a step (development step) of alkali-development of the layer of the laminated structure to form a layer of the patterned laminated structure. Further, if necessary, after alkaline development, further photo-curing or thermosetting (post-cure process) is performed to completely cure the layer of the laminated structure, and a highly reliable flexible printed wiring board can be obtained. ..

Further, the flexible printed wiring board using the laminated structure of the present invention can be manufactured, for example, according to the procedure shown in the process diagram of FIG. That is, a step of forming a layer of the laminated structure of the present invention on a flexible printed wiring base material on which a conductor circuit is formed (lamination step), and a step of irradiating the layer of the laminated structure with active energy rays in a pattern (exposure). Step), a step of heating the layer of the laminated structure (heating (PEB) step), and a step of alkaline-developing the layer of the laminated structure to form a layer of the patterned laminated structure (development step). ) Is included in the manufacturing method. Further, if necessary, after alkaline development, further photo-curing or thermosetting (post-cure process) is performed to completely cure the layer of the laminated structure, and a highly reliable flexible printed wiring board can be obtained. ..

Hereinafter, each step in FIG. 1 or 2 will be described in more detail.
[Laminating process]
In this step, the flexible printed wiring base material 1 on which the conductor circuit 2 is formed has a resin layer 3 (resin layer (A)) of an alkali-developable resin composition containing an alkali-soluble resin and the like, and a resin layer 3 on the resin layer 3. , A laminated structure composed of the resin layer 4 (resin layer (B)) of the curable resin composition of the present invention is formed. Here, each resin layer constituting the laminated structure forms the resin layers 3 and 4 by, for example, sequentially applying and drying the resin composition constituting the resin layers 3 and 4 to the wiring base material 1. Alternatively, the resin composition constituting the resin layers 3 and 4 in the form of a dry film having a two-layer structure may be formed by laminating the wiring base material 1.

The resin composition may be applied to the wiring substrate by a known method such as a blade coater, a lip coater, a comma coater, or a film coater. In addition, the drying method uses a hot air circulation type drying furnace, IR furnace, hot plate, convection oven, etc., which is equipped with a heat source of the heating method using steam, and the hot air in the dryer is brought into countercurrent contact, and is supported by the nozzle. A known method such as a method of spraying on the body may be used.

[Exposure process]
In this step, the photopolymerization initiator contained in the resin layer 4 is activated in a negative pattern by irradiation with active energy rays, and the exposed portion is cured. As the exposure machine, a direct drawing device, an exposure machine equipped with a metal halide lamp, or the like can be used. The mask for patterned exposure is a negative type 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 in this range, the photopolymerization initiator can be activated efficiently. The exposure amount varies depending on the film thickness and the like, but can be ^{, for example, 50 to 1500 mJ / cm 2.}

[PEB process]
In this step, after the exposure, the exposed portion is cured by heating the resin layer. By this step, the base generated in the exposure step of the resin layer (B) composed of a photopolymerization initiator having a function as a photobase generator or a composition in which the photopolymerization initiator and the photobase generator are used in combination. Therefore, the resin layer (B) can be cured to a deep part. The heating temperature is, for example, 70 to 150 ° C. The heating time is, for example, 1 to 120 minutes. Since the curing of the resin composition in the present invention is, for example, a ring-opening reaction of the epoxy resin by a thermal reaction, strain and curing shrinkage can be suppressed as compared with the case where curing proceeds by a photoradical reaction.

[Development process]
In this step, the unexposed portion is removed by alkaline development to form a negative patterned insulating film, for example, a coverlay and a solder resist. As the developing method, a known method such as dipping can be used. As the developing solution, sodium carbonate, potassium carbonate, potassium hydroxide, amines, imidazoles such as 2-methylimidazole, an alkaline aqueous solution such as tetramethylammonium hydroxide aqueous solution (TMAH), or a mixed solution thereof may be used. Can be used.

[Post-cure process]
After the developing step, the insulating film may be further irradiated with light, or may be heated at, for example, 150 ° C. or higher.

Hereinafter, the present invention will be described in more detail with reference to Examples, Reference Examples and Comparative Examples, but the present invention is not limited to these Examples, Reference Examples and Comparative Examples.

(Synthesis Example 1)
Aliphatic diamine (manufactured by Crowder Japan, product name PRIAMINE 1075) 28 derived from dimer acid having 36 carbon atoms as diamine diamine (a) in a four-necked 300 mL flask equipped with a nitrogen gas introduction tube, a thermometer, and a stirrer. .61 g (0.052 mol), 4.26 g (0.028 mol) of 3,5-diaminobenzoic acid as a carboxyl group-containing diamine (b), and 85.8 g of γ-butyrolactone were charged and dissolved at room temperature.

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 charged, and 30 minutes at room temperature. Retained. Further, 30 g of toluene was charged, the temperature was raised to 160 ° C. to remove water generated together with toluene, and the mixture was held for 3 hours and cooled to room temperature to obtain a solution containing an imidized product.

14.30 g (0.068 mol) of trimethylhexamethylene diisocyanate as the diisocyanate compound (e) was charged into the obtained imidized solution, kept at a temperature of 160 ° C. for 32 hours, and diluted with 21.4 g of cyclohexanone. A solution (A-1) containing a polyamide-imide resin was obtained. 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 diamine diamine (a) content of 40.0% by mass.

(Synthesis Example 2)
Aliphatic diamine (manufactured by Claude Japan, product name PRIAMINE 1075) 29 derived from dimer acid having 36 carbon atoms as diamine diamine (a) in a four-necked 300 mL flask equipped with a nitrogen gas introduction tube, a thermometer, and a stirrer. .49 g (0.054 mol), 4.02 g (0.026 mol) of 3,5-diaminobenzoic acid as a carboxyl group-containing diamine (b), and 73.5 g of γ-butyrolactone were charged and dissolved at room temperature.

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 charged, and 30 minutes at room temperature. Retained. Further, 30 g of toluene was charged, the temperature was raised to 160 ° C. to remove water generated together with toluene, and the mixture was held for 3 hours and cooled to room temperature to obtain a solution containing an imidized product.

6.90 g (0.033 mol) of trimethylhexamethylene diisocyanate and 8.61 g (0.033 mol) of dicyclohexylmethane diisocyanate as the diisocyanate compound (e) were charged into the obtained solution containing the imidized product, and the temperature was 160 ° C. A solution (A-2) containing a polyamide-imide resin was obtained by diluting with 36.8 g of cyclohexanone. 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 diamine diamine (a) content of 40.1% by mass.

(Synthesis Example 3)
2.2'-Bis [4- (4-aminophenoxy) phenyl] propane 6.98 g, 3,5-diaminobenzoic acid in a four-necked 300 mL flask equipped with a nitrogen gas introduction tube, a thermometer, and a stirrer. 80 g, 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 charged and dissolved at room temperature.

Then, 17.84 g of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride and 2.88 g of trimellitic anhydride were charged and kept at room temperature for 30 minutes. Further, 30 g of toluene was charged, the temperature was raised to 160 ° C. to remove water generated together with toluene, and the mixture was held for 3 hours and cooled to room temperature to obtain an imidized solution.

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

(Synthesis Example 4)
3,3'-diamino-4,4'-dihydroxydiphenylsulfone 22.4 g, 2,2'-bis [4] in a separable three-necked flask equipped with a stirrer, nitrogen introduction pipe, fractional ring, and cooling ring. Add 8.2 g of-(4-aminophenoxy) phenyl] propane, 30 g of NMP, 30 g of γ-butyrolactone, 27.9 g of 4,4'-oxydiphthalic anhydride, and 3.8 g of trimellitic anhydride. The mixture was stirred at room temperature and 100 rpm for 4 hours under a nitrogen atmosphere. Next, 20 g of toluene was added, and the mixture was stirred for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 ° C. and 150 rpm to obtain a polyimide resin solution (PI-1) having a phenolic hydroxyl group and a carboxyl group.
The acid value of the obtained resin (solid content) was 18 mgKOH, Mw was 10,000, and the hydroxyl group equivalent was 390.

(Examples 1 to 4, Reference Examples 1 to 5 and Comparative Examples 1 and 2)
According to the composition of the components shown in Table 1, the materials described in Examples 1 to 4, Reference Examples 1 to 5 and Comparative Examples 1 and 2 were mixed, premixed with a stirrer, and kneaded with a three-roll mill. Each resin composition for forming a resin layer was prepared. Unless otherwise specified, the values in the table are parts by mass of solid content.

＊１）ポリアミドイミド樹脂含有溶液（Ａ−１）〜（Ａ−３）：合成例１〜合成例３
＊２）アルカリ溶解性樹脂（ＰＩ−１）：合成例４
＊３）光重合開始剤：オキシム系光重合開始剤ＩＲＧＡＣＵＲＥ ＯＸＥ０２（ＢＡＳＦ社製）
＊４）エポキシ樹脂：ビスフェノールＡ型エポキシ樹脂Ｅ８２８，エポキシ当量１９０，質量平均分子量３８０（三菱化学（株）製）

* 1) Polyamide-imide resin-containing solutions (A-1) to (A-3): Synthesis Examples 1 to 3
* 2) Alkali-soluble resin (PI-1): Synthesis Example 4
* 3) Photopolymerization initiator: Oxime-based photopolymerization initiator IRGACURE OXE02 (manufactured by BASF)
* 4) Epoxy resin: Bisphenol A type epoxy resin E828, epoxy equivalent 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)

<Formation of resin layer>
A flexible printed wiring board on which a circuit having a copper thickness of 18 μm was formed was prepared, and pretreatment was performed using CZ-8100 manufactured by MEC. Then, on the pretreated flexible printed wiring board, the resin compositions obtained in Examples 1 to 4, Reference Examples 1 to 5 and Comparative Examples 1 and 2 are dried to have a film thickness of 30 μm. Was applied. Then, it was dried in a hot air circulation type drying oven at 90 degreeC for 30 minutes to form an uncured resin layer.

<Developability (alkali solubility)>
For the uncured resin layer on each flexible printed wiring board on which the resin layer was formed as described above, first, an exposure device (HMW-680-GW20) equipped with a metal halide lamp was used, and 300 mJ / cm was passed through a negative mask. ^The pattern was exposed so as to form an opening having a diameter of 200 μm in 2. The substrate having the resin layer after exposure was heat-treated at 90 ° C. for 30 minutes. After that, the substrate was immersed in a 1% by mass aqueous sodium carbonate solution at 30 ° C. and developed for 1 minute, and the state of pattern formation was observed to evaluate the developability (alkali solubility). The evaluation criteria are as follows.
◯: The exposed part shows the development resistance, the unexposed part shows the developability, and the pattern formation is good.
X: The unexposed area shows developability, but the resolution pattern formation is poor (insufficient resolution).

<Heat resistance (solder heat resistance)>
(Preparation of evaluation board)
For the uncured resin layer on each flexible printed wiring board on which the resin layer was formed as described above, first, an exposure device (HMW-680-GW20) equipped with a metal halide lamp was used, and 300 mJ / cm was passed through a negative mask. ^The pattern was exposed so as to form an opening having a diameter of 200 μm in 2. Then, the PEB step was carried out at 90 ° C. for 30 minutes, then development (30 ° C., 0.2 MPa, 1 mass% Na ₂ CO ₃ aqueous solution) was carried out for 60 seconds, and the mixture was thermoset at 150 ° C. for 60 minutes. A flexible printed wiring board (evaluation board) on which a resin layer was formed was produced.
(Evaluation method)
A rosin-based flux is applied to the evaluation substrate prepared as described above, and the evaluation substrate is immersed in a solder bath set at 260 ° C. for 20 seconds (10 seconds x 2 times) to cause swelling of the cured coating film (resin layer).・ Peeling was observed and heat resistance (solder heat resistance) was evaluated. The evaluation criteria are as follows.
◯: There was no swelling or peeling even after immersion for 10 seconds × 2 times.
X: When immersed for 10 seconds × 1 time, swelling and peeling occurred.

<Chemical resistance (gold plating resistance)>
Using the same evaluation substrate as the evaluation of heat resistance, the evaluation was performed by the following method.
The evaluation substrate is plated with 5 μm of nickel and 0.05 μm of gold at 80 to 90 ° C. using a commercially available electroless nickel plating bath and electroless gold plating bath, and the substrate and the resin layer are observed to withstand chemicals. The sex (gold plating resistance) was evaluated. The evaluation criteria are as follows.
◯: No penetration between the substrate and the coating film (resin layer).
Δ: Those in which penetration is confirmed between the substrate and the coating film (resin layer).
X: A part of the coating film (resin layer) is peeled off.

<Repulsion (springback)>
(Preparation of test piece)
Each of the resin compositions obtained in Examples 1 to 4, Reference Examples 1 to 5 and Comparative Examples 1 and 2 was applied onto a polyimide film so that the film thickness after drying was 30 μm, and hot air circulation drying was performed. It was dried in a furnace at 90 ° C. for 30 minutes to form an uncured resin layer. Then, using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, exposure was performed at 300 mJ / cm ² without using a mask. Then, after performing a PEB step at 90 ° C. for 30 minutes, development (30 ° C., 0.2 MPa, 1 mass% Na ₂ CO ₃ aqueous solution) is performed for 60 seconds, and thermosetting is performed at 150 ° C. × 60 minutes. A polyimide film test piece on which a cured resin layer was formed was prepared.
(Evaluation method)
The polyimide film test piece produced as described above was cut into a size of 2 cm × 7 cm, and both ends on the long side were joined to form a band-shaped ring, and the mating portions at both ends were fixed to an electronic balance with tape. The repulsive force (g) was measured as the repulsive force (g) when the ring was pressed with a glass plate so that the distance between the top and bottom of the ring was 3 mm in the bent state, and the repulsive property (springback property) was evaluated. The evaluation criteria are as follows.
◯: Less than 30 g.
Δ: 30 g or more and less than 45 g.
X: 45 g or more.

<Amount of warpage after curing>
Using the same test piece as in the evaluation of resilience, the evaluation was performed by the following method.
After cutting the test piece into 5 cm x 5 cm, place the substrate on a horizontal test table with the warped surface facing up, and measure the distances from the test table at each of the four apex to 1 mm with a straightedge. The maximum value at four locations was used as the amount of warpage, and the amount of warpage after curing was evaluated. The evaluation criteria are as follows.
◯: Warpage amount is less than 3 mm.
Δ: Warpage amount of 3 mm or more and less than 6 mm.
×: Warpage amount 6 mm or more

The evaluation results are shown in Table 2.

(Examples 5 and 6 and Reference Example 6)
According to the composition of the components shown in Table 3, the materials described in Examples 5 and 6 and Reference Example 6 are blended, premixed with a stirrer, and then kneaded with a three-roll mill to form a resin layer (A). Each resin composition for forming the resin layer (B) and each resin composition for forming the resin layer (B) were prepared. Unless otherwise specified, the values in the table are parts by mass of solid content.

＊１）ポリアミドイミド樹脂含有溶液（Ａ−１）〜（Ａ−３）：合成例１〜合成例３
＊２）アルカリ溶解性樹脂（ＰＩ−１）：合成例４
＊３）光重合開始剤：オキシム系光重合開始剤ＩＲＧＡＣＵＲＥ ＯＸＥ０２（ＢＡＳＦ社製）
＊４）エポキシ樹脂：ビスフェノールＡ型エポキシ樹脂Ｅ８２８，エポキシ当量１９０，質量平均分子量３８０（三菱化学（株）製）
＊５）アルカリ溶解性樹脂： Ｐ７−５３２：ポリウレタンアクリレート，酸価４７ｍｇＫＯＨ／ｇ（共栄社化学（株）製）
＊６）光硬化性モノマー： ＢＰＥ−５００：エトキシ化ビスフェノールＡジメタクリレート（新中村化学（株）製）

* 1) Polyamide-imide resin-containing solutions (A-1) to (A-3): Synthesis Examples 1 to 3
* 2) Alkali-soluble resin (PI-1): Synthesis Example 4
* 3) Photopolymerization initiator: Oxime-based photopolymerization initiator IRGACURE OXE02 (manufactured by BASF)
* 4) Epoxy resin: Bisphenol A type epoxy resin E828, epoxy equivalent 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)
* 5) Alkali-soluble resin: P7-532: Polyurethane acrylate, acid value 47 mgKOH / g (manufactured by Kyoeisha Chemical Co., Ltd.)
* 6) Photocurable monomer: BPE-500: Ethoxylated bisphenol A dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)

<Formation of resin layer (A)>
A flexible printed wiring board on which a circuit having a copper thickness of 18 μm was formed was prepared, and pretreatment was performed using CZ-8100 manufactured by MEC. Then, on the pretreated flexible printed wiring board, each resin composition for forming the resin layer (A) obtained in Examples 5 and 6 and Reference Example 6 was dried to have a film thickness of 20 μm. It was applied so as to become. Then, it was dried in a hot air circulation type drying oven at 90 degreeC for 30 minutes to form a resin layer.

<Formation of resin layer (B)>
Each resin composition for forming the resin layer (B) obtained in Examples 5 and 6 and Reference Example 6 on the resin layer (A) formed above has a film thickness of 10 μm after drying. It was applied so as to become. Then, it was dried in a hot air circulation type drying oven at 90 degreeC for 30 minutes to form a resin layer (B).

In this way, an uncured laminated structure composed of the resin layer (A) and the resin layer (B) described in Examples 5 and 6 and Reference Example 6 was formed on the flexible printed wiring board.

For the uncured laminated structure formed as described above, the evaluations performed on the uncured resin layers in Examples 1 to 4, Reference Examples 1 to 5 and Comparative Examples 1 and 2 were carried out in the same manner. did.
The evaluation results are shown in Table 4.

As is clear from the evaluation results shown in Tables 2 and 4, the resin compositions of each example have excellent developability, heat resistance, low resilience, and low warpage after heating. Was confirmed.

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

Claims (7)

A curable resin composition containing an alkali-soluble polyamide-imide resin, an alkali-soluble polyimide resin, and a curable compound.
The blending ratio of the polyamide-imide resin and the polyimide resin is 98: 2 to 80:20 in terms of mass ratio.
A curable resin composition, wherein the alkali-soluble polyamide-imide resin is a polyamide-imide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2).

(X ₁ is a residue of an aliphatic diamine (a) derived from dimer acid having 24 to 48 carbon atoms, X ₂ is a residue of an aromatic diamine (b) having a carboxyl group, and Y is an independently cyclohexane ring or Aromatic ring.) The alkali solubility of the polyimide resin, the curable resin composition according to claim 1, characterized in that it has a carboxyl group. The curable resin composition according to claim 2, wherein the alkali-soluble polyimide resin has a carboxyl group and a phenolic hydroxyl group. The curable resin composition according to any one of claims 1 to 3 , wherein the curable compound is an epoxy resin. A laminated structure having a resin layer (A) and a resin layer (B) laminated on a base material via the resin layer (A).
The resin layer (B) comprises the curable resin composition according to any one of claims 1 to 4 , and the resin layer (A) contains an alkali-soluble resin and a thermosetting compound. A laminated structure characterized by being composed of an alkali-developable resin composition. A cured product comprising the curable resin composition according to any one of claims 1 to 4 or the laminated structure according to claim 5. An electronic component having an insulating film made of the cured product according to claim 6.

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