JP2022159177A - Curable resin composition, cured product, and electronic component - Google Patents

Abstract

To provide a curable resin composition that allows reduced adhesion between its resultant cured products that are stacked and stored.SOLUTION: A curable resin composition contains (A) an alkali-soluble polyimide resin, (B) a cellulose derivative, (C) a thermosetting compound, and (D) a photo-base generator. Cured products of the curable resin composition show reduced adhesion between them when stored in a stacked manner.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a curable resin composition, a cured product and an electronic component, and more particularly to an alkali-developable photo- and thermosetting curable resin composition, a cured product and an electronic component.

Conventionally, a non-photosensitive resin structure formed by applying a thermosetting adhesive to a film such as polyimide has been used as a protective film for a flexible printed wiring board. As a method of patterning such a non-photosensitive resin structure and forming it on a flexible printed wiring board, conventionally, a method of forming holes by punching and then thermocompression bonding on the flexible printed wiring board has been adopted. Alternatively, a method has also been adopted in which a solvent-soluble thermosetting resin composition is directly pattern-printed on a flexible printed wiring board and thermally cured to form a pattern. In particular, polyimide films have been used as suitable materials for flexible printed wiring boards because they are flexible and have excellent heat resistance, mechanical properties, and electrical properties (see, for example, Patent Document 1).
However, with the above-mentioned conventional method, the shape of the pattern ends is lost due to the bleeding of the resin during coating or thermocompression bonding. However, it has been difficult to form a fine pattern to be used.

WO2012/133665

On the other hand, it is also conceivable to apply a photosensitive solder resist, which is known as a permanent circuit protective film capable of microfabrication, as a coverlay for a flexible printed wiring board. A photosensitive solder resist in a flexible printed wiring board requires a low cross-linking density in order to impart flexibility, and an improvement in heat resistance is also required. Since flexible substrates are thin and easily bent, they are often piled up and fixed, stored, and transported. Due to its storage and transportation environment, it is exposed to high temperatures. When a photosensitive solder resist is applied to the coverlay, the area that protects the flexible printed wiring board becomes wider. They may stick together. In recent years, there has also been an increasing demand for thin films in fields using rigid substrates. Not only flexible substrates, but also thin substrates such as rigid substrates with a thickness of 0.1 mm, the phenomenon of sticking of coating films to each other may occur.

The object of the present invention in view of the above problems is that the dry coating film has good developability, the obtained cured product has good heat resistance and flexibility, and the obtained cured product is stacked and stored. The object of the present invention is to provide a curable resin composition having a property of less sticking to the surface.

The inventors of the present invention conducted intensive studies to achieve the above object. As a result, it was found that by blending a cellulose derivative into the curable resin composition and adding an alkali-soluble polyimide resin to a predetermined blend, sticking between the resulting cured products is reduced. was completed.

That is, the object of the present invention is
(A) an alkali-soluble polyimide resin;
(B) a cellulose derivative;
(C) a thermosetting compound;
(D) It was found that the curable resin composition is characterized by containing a photobase generator.

In addition, (A) the alkali-soluble polyimide resin preferably has a carboxyl group, and (A) the alkali-soluble polyimide resin preferably has a carboxyl group and a phenolic hydroxyl group.

Furthermore, it is preferable that the curable resin composition of the present invention further contains (E) an alkali-soluble polyamide-imide resin.

Moreover, (C) the thermosetting compound is preferably an epoxy resin.

Furthermore, the above object of the present invention can also be achieved by a cured product obtained from the curable composition of the present invention and an electronic component having an insulating film made of this cured product.

The dry coating film of the curable composition of the present invention has good developability, and the cured product obtained from the curable composition of the present invention has good heat resistance and flexibility, and can be stacked and stored. It has a characteristic that sticking is small when it is applied.

It is explanatory drawing of the MIT test which performed the evaluation board|substrate produced in the Example as a test piece.

<Curable resin composition>
The curable resin composition of the present invention is
(A) an alkali-soluble polyimide resin;
(B) a cellulose derivative;
(C) a thermosetting compound;
(D) a photobase generator.

[(A) Alkali-soluble polyimide resin]
The (A) alkali-soluble polyimide resin contained in the curable resin composition of the present invention has an alkali-soluble functional group (hereinafter also referred to as an alkali-soluble group).

The alkali-soluble functional group is a functional group that enables the curable resin composition of the present invention to be developed with an alkaline solution, and includes, for example, a carboxyl group and a phenolic hydroxyl group.

Examples of such (A) 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. Further, the imidization may be carried out by thermal imidization or by chemical imidization, and these may be used in combination.

Examples of the carboxylic anhydride component include tetracarboxylic anhydrides and tricarboxylic anhydrides, but are not limited to these acid anhydrides. Acid anhydride groups that react with amino groups and isocyanate groups and Any compound having a carboxyl group can be used, including its derivatives. Also, 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 polyetheramines, diamines having a carboxyl group, diamines having a phenolic hydroxyl group, 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 phenolic hydroxyl groups and carboxyl groups. Also, these amine components may be used alone or in combination.

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

In synthesizing 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 does not react with the carboxylic acid anhydrides, amines, and isocyanates that are raw materials and dissolves these raw materials, and its structure is not particularly limited. In particular, aprotic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, and γ-butyrolactone are preferred because of their high solubility of raw materials.

(A) The alkali-soluble polyimide resin preferably has a carboxyl group as an alkali-soluble group, and particularly preferably has both a carboxyl group and a phenolic hydroxyl group as an alkali-soluble group.

(A) alkali-soluble polyimide resin, the alkali solubility of the polyimide resin (developability), the viewpoint of improving the balance with other properties such as mechanical properties of the cured product of the curable resin composition containing the polyimide resin Therefore, the acid value (solid content acid value) is preferably 20 to 200 mgKOH/g, particularly preferably 60 to 150 mgKOH/g.

Further, the molecular weight of the alkali-soluble polyimide resin (A) is preferably a mass average molecular weight Mw of 100,000 or less, more preferably 1,000 to 100,000, in consideration of developability and cured coating film properties. Preferably, 2,000 to 50,000 is more preferable.

(A) The total amount of the alkali-soluble polyimide resin and the alkali-soluble polyamideimide resin (E), which is an optional component described later, is based on 100 parts by mass of the curable resin composition of the present invention, for example , 10 to 85 parts by mass, preferably 15 to 80 parts by mass, particularly preferably 20 to 75 parts by mass.

[(B) cellulose derivative]
The (B) cellulose derivative contained in the curable resin composition of the present invention is preferably soluble in an organic solvent and has a high glass transition temperature (Tg). Cellulose derivatives include cellulose ethers, carboxymethyl cellulose, cellulose esters, etc., which will be described later.

Cellulose ethers include ethyl cellulose, hydroxyalkyl cellulose and the like, and commercial products of ethyl cellulose include Ethocel (registered trademark) 4, Ethocel 7, Ethocel 10, Ethocel 14, Ethocel 20, Ethocel 45, Ethocel 70, Ethocel 100 and Ethocel. 200, Ethocel 300 (all trade names manufactured by Dow Chemical Company), and commercial products of hydroxyalkyl cellulose include Metolose SM, Metolose 60SH, Metolose 65SH, Metolose 90SH, Metolose SEB, and Metolose SNB (all of which are Shin-Etsu Chemical Co., Ltd. ( (trade name) manufactured by Co., Ltd.).

In addition, commercial products of carboxymethyl cellulose include CMCAB-641-0.2 (trade name manufactured by Eastman Chemical Co.), Sunrose F, Sunrose A, Sunrose P, Sunrose S, and Sunrose B (all product name of Nippon Paper Industries Co., Ltd.) and the like.

（式（１）中、Ｒ_１、Ｒ_２およびＲ_３は、それぞれ独立して、水素、アシル基、または式（２）

（式（２）中、Ｒ_４は、水素またはメチル基であり、Ｒ_５は、水素、メチル基、エチル基、またはグリシジル基である。）で表される基を表し、Ｒ_１、Ｒ_２およびＲ_３の少なくとも一つは水素であり、ｎは１以上の整数であり、その上限は後述する分子量から規制される。）で示される化合物が挙げられる。 A more preferable cellulose derivative is a cellulose ester obtained by esterifying the hydroxyl group of cellulose with an organic acid.

(In formula (1), R ₁ , R ₂ and R ₃ are each independently hydrogen, acyl group, or formula (2)

(In formula (2), R ₄ is hydrogen or a methyl group, and R ₅ is hydrogen, a methyl group, an ethyl group, or a glycidyl group.) represents a group represented by R ₁ and R ₂ and R ₃ are hydrogen, n is an integer of 1 or more, and its upper limit is regulated by the molecular weight described later. ) can be mentioned.

In the cellulose ester represented by the above formula (1), the acyl group content relative to the cellulose resin is in the range of more than 0 to 60 wt%, preferably in the range of 5 to 55 wt%.

In addition, in the cellulose ester represented by the above formula (1), the hydroxyl group content relative to the cellulose resin is 0 to 6 wt%, the acetyl group content as acyl groups is 0 to 40 wt%, and the propionyl group or/and butyryl group content is is preferably in the range of 0 to 55 wt%, and the content of the group represented by formula (2) is preferably in the range of 0 to 20 wt%. As used herein, "wt%" is the weight percent of hydrogen, acyl groups, or groups represented by formula (2) relative to the weight of cellulose.

Commercial products of such cellulose esters include cellulose acetates such as CA-398-3, CA-398-6, CA-398-10, CA-398-30, CA-394-60S, and cellulose acetate butyrate. As, CAB-551-0.01, CAB-551-0.2, CAB-553-0.4, CAB-531-1, CAB-500-5, CAB-381-0.1, CAB-381- CAP-504-0.0.5, CAB-381-2, CAB-381-20, CAB-381-20BP, CAB-321-0.1, CAB-171-15, etc. as cellulose acetate propionates. 2, CAP-482-0.5, CAP-482-20 (all of the above cellulose derivatives are trade names manufactured by Eastman Chemical Co.), and the like. Among these, cellulose acetate butyrate and cellulose acetate propionate are preferable from the viewpoint of solubility in solvents.
In addition, the above cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are treated with (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, ( A cellulose derivative containing a group represented by the formula (2) can be obtained by reacting with glycidyl meth)acrylate or the like. By using the cellulose derivative containing the group represented by the formula (2), the evaluation result of the sticking property becomes better.

Although the number average molecular weight of (B) the cellulose derivative is not particularly limited, it is preferably 5,000 to 500,000, more preferably 10,000 to 100,000, still more preferably 10,000 to 30,000. When the molecular weight is within the above range, sticking is small, that is, the evaluation result of sticking property is good, and the viscosity of the curable resin composition falls within an appropriate range.
In particular, when using (E) an alkali-soluble polyamideimide resin, the compatibility between the (C) thermosetting compound and (B) the cellulose derivative is good before heat curing, and the polymer component is in the dry coating film. This is thought to be due to the fact that the particles are present in a dispersed state, and as a result, sticking is small, that is, the evaluation result of sticking property is good. Further, when (E) the alkali-soluble polyamide-imide resin is used, the flexibility and sticking property after curing are improved.

The glass transition temperature Tg as used herein refers to the glass transition temperature measured by thermomechanical analysis (DSC) according to the method described in JIS C 6481:1996, "5.17.5 DSC method".

The cellulose derivative used in the present invention is preferably derived from natural products from the viewpoint of fossil fuel depletion. Furthermore, the starting material used for the cellulose derivative of the present invention can be produced from recycled products such as regenerated pulp, and it is possible to provide a composition that is preferable from the environmental aspect of CO ₂ reduction.

(B) A cellulose derivative can be used individually or in mixture of 2 or more types. (B) The amount of the cellulose derivative is, for example, 0.5 parts by mass with respect to 100 parts by mass of (A) the alkali-soluble polyimide resin (and (E) the alkali-soluble polyamideimide resin as an optional component described later). part or more and 20 mass parts or less, preferably 1 mass part or more and 15 mass parts or less, more preferably 4 mass parts or more and 10 mass parts or less. When it is within the above range, sticking is small, that is, the evaluation result of sticking property is good, and the viscosity of the curable resin composition falls within an appropriate range.

[(C) thermosetting compound]
The curable resin composition of the present invention contains (C) a thermosetting compound from the viewpoint of imparting heat resistance and chemical resistance to the cured product after thermosetting. (C) The thermosetting compound has a functional group capable of undergoing an addition reaction with a carboxyl group or a phenolic hydroxyl group by heat.

(C) Thermosetting compounds include epoxy resins, urethane resins, polyester resins, hydroxyl group-, amino- or carboxyl-containing polyurethanes, polyesters, polycarbonates, polyols, phenoxy resins, acrylic copolymer resins, vinyl resins, oxazine resins, A known and commonly used thermosetting resin such as a cyanate resin can be used.

Above all, from the viewpoint of heat resistance and chemical resistance, (C) the thermosetting compound is preferably an epoxy resin.

Specific examples of epoxy resins include jER828 manufactured by Mitsubishi Chemical Corporation, EHPE3150 manufactured by Daicel Corporation, EPICLON840 manufactured by DIC Corporation, Epotote YD-011 manufactured by Nippon Steel Chemical & Materials, and D.I. E. R. 317, bisphenol A type epoxy resins such as Sumiepoxi ESA-011 (both trade names) manufactured by Sumitomo Chemical; , Dow Chemical Company D.I. E. R. 542, brominated epoxy resins such as Sumiepoxy ESB-400 (both trade names) manufactured by Sumitomo Chemical; jER152 manufactured by Mitsubishi Chemical; E. N. 431, EPICLON N-730 manufactured by DIC, YDCN-701 manufactured by Nippon Steel Chemical & Materials, EPPN-201 manufactured by Nippon Kayaku, Sumiepoxy ESCN-195X manufactured by Sumitomo Chemical Co., etc. (all trade names) Novolak type epoxy resin; EPICLON830 manufactured by DIC Corporation, jER807 manufactured by Mitsubishi Chemical Corporation, Epotote YDF-170, YDF-175, YDF-2004 manufactured by Nippon Steel Chemical & Materials Co., Ltd. Bisphenol F type epoxy resin (all trade names) ; Hydrogenated bisphenol A type epoxy resin such as Epotato ST-2004 (trade name) manufactured by Nippon Steel Chemical &Materials; jER604 manufactured by Mitsubishi Chemical Corporation; Glycidylamine type epoxy resin such as Sumiepoxy ELM-120 (both trade names); Hydantoin type epoxy resin; Daicel Celoxide 2021 etc. (both trade names) alicyclic epoxy resin; EPPN-501, etc. (all trade names) of trihydroxyphenylmethane type epoxy resins; Mitsubishi Chemical Corporation YL-6056, YX-4000, YL-6121 (all trade names), etc. of bixylenol type or biphenol type Epoxy resins or mixtures thereof; EBPS-200 manufactured by Nippon Kayaku, EPX-30 manufactured by ADEKA, bisphenol S type epoxy resins such as EXA-1514 (trade name) manufactured by DIC; jER157S manufactured by Mitsubishi Chemical Corporation (product Bisphenol A novolac type epoxy resins such as bisphenol A novolac type epoxy resins such as TEPIC manufactured by Nissan Chemical Co., Ltd. (both are trade names). Biphenyl novolac type epoxy resins; Naphthalene group-containing epoxy resins such as HP-4032 manufactured by DIC Corporation; and epoxy resins having a dicyclopentadiene skeleton such as HP-7200 manufactured by DIC Corporation.

(C) The thermosetting compound may be contained in any amount, but the equivalent ratio (alkali-soluble It is preferred that the ratio of 1:0.1 to 1:10 of the functional group: thermosetting group such as epoxy group) be obtained.

[(D) Photobase generator]
The curable resin composition of the present invention includes (A) an alkali-soluble polyimide resin (and (E) an alkali-soluble polyamideimide resin as an optional component described later) and (C) an addition reaction with a thermosetting compound. (D) a photobase generator capable of functioning as a catalyst for (D) The photobase generator is a catalyst for the addition reaction between the polyimide resin having a carboxyl group and the thermosetting component when the molecular structure changes or the molecule is cleaved by irradiation with light such as ultraviolet light or visible light. It is a compound that produces one or more basic substances that can function as

Basic substances include, for example, secondary amines and tertiary amines.

Examples of photobase generators include α-aminoacetophenone compounds, oxime ester compounds, acyloxyimino groups, N-formylated aromatic amino groups, N-acylated aromatic amino groups, nitrobenzyl carbamate groups, and alkoxybenzyls. A compound having a substituent such as a carbamate group is included. Among them, oxime ester compounds and α-aminoacetophenone compounds are preferred. As α-aminoacetophenone compounds, those having two or more nitrogen atoms are particularly preferred.

Other photobase generators include WPBG-018 (trade name: 9-anthrylmethylN,N'-diethylcarbamate), WPBG-027 (trade name: (E)-1-[3-(2-hydroxyphenyl)-2-propenoyl ]piperidine), WPBG-082 (trade name: guanidinium2-(3-benzoylphenyl)propionate), WPBG-140 (trade name: 1-(anthraquinon-2-yl)ethyl imidazolecarboxylate), etc. (Fujifilm Wako Pure Chemical Industries, Ltd. ) can also be used.

The α-aminoacetophenone compound has a benzoin ether bond in its molecule, and when exposed to light, it undergoes intramolecular cleavage to produce a basic substance (amine) that acts as a curing catalyst. Specific examples of α-aminoacetophenone compounds include (4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane (
Omnirad 369, trade name, manufactured by IGM Resins), 4-(methylthiobenzoyl)-1-methyl-1-morpholinoethane (Omnirad 907, trade name, manufactured by IGM Resins), 2-(dimethyl Amino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (Omnirad 379, trade name, manufactured by IGM Resins) and other commercially available A compound or a solution thereof can be used.

As the oxime ester compound, any compound can be used as long as it is a compound that generates a basic substance upon irradiation with light. As such an oxime ester compound, an oxime ester photobase generator having a group represented by the following general formula (3) is preferable.

(In the formula, R ₆ is a hydrogen atom, an unsubstituted or C 1-6 alkyl group, a phenyl group or a phenyl group substituted with a halogen atom, an unsubstituted C 1 group substituted with one or more hydroxyl groups, -20 alkyl groups, said alkyl groups interrupted by one or more oxygen atoms, unsubstituted or C5-8 cycloalkyl groups substituted with C1-6 alkyl groups or phenyl groups, unsubstituted or an alkanoyl group having 2 to 20 carbon atoms or a benzoyl group substituted with an alkyl group having 1 to 6 carbon atoms or a phenyl group, and R ₇ is unsubstituted or an alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen A phenyl group substituted with an atom, an alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with one or more hydroxyl groups, the alkyl group interrupted by one or more oxygen atoms, unsubstituted or having 1 to 1 carbon atoms a cycloalkyl group having 5 to 8 carbon atoms substituted with an alkyl group of 6 or a phenyl group, an alkanoyl group having 2 to 20 carbon atoms or a benzoyl group unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms or a phenyl group; represents.)

Examples of commercially available oxime ester photobase generators include IRGACURE OXE01 and IRGACURE OXE02 manufactured by BASF Japan, N-1919 and NCI-831 manufactured by ADEKA. Compounds having two oxime ester groups in the molecule, which are described in Japanese Patent No. 4344400, can also be preferably used.

In addition, JP 2004-359639, JP 2005-097141, JP 2005-220097, JP 2006-160634, JP 2008-094770, JP 2008-509967, Examples include carbazole oxime ester compounds described in JP-T-2009-040762 and JP-A-2011-80036.

Such photobase generators may be used singly or in combination of two or more. The amount of the (D) photobase generator in the curable resin composition of the present invention is (A) relative to 100 parts by mass of the alkali-soluble polyimide resin, or (E) an alkali-soluble polyamideimide described later When the resin is included, for example, 0.1 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the total amount of (A) the alkali-soluble polyimide resin and (E) the alkali-soluble polyamideimide resin and preferably 0.2 parts by mass or more and 20 parts by mass or less.

When the amount is 0.1 part by mass or more, a good contrast of development resistance between the light-irradiated area and the non-irradiated area can be obtained. Moreover, when it is 40 parts by mass or less, the properties of the cured product are improved.

[(E) alkali-soluble polyamideimide resin]
From the viewpoint of improving heat resistance and developability, the curable resin composition of the present invention preferably contains (E) an alkali-soluble polyamide-imide resin.

(E) Alkali-soluble polyamide-imide resin contains at least one functional group selected from phenolic hydroxyl group and carboxyl group, and can be developed with an alkaline solution.

Such an alkali-soluble polyamide-imide resin is, for example, a resin obtained by reacting a carboxylic acid anhydride component and an amine component to obtain an imidized product, and then reacting the obtained imidized product with an isocyanate component. etc. 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 by chemical imidization, and these may be used in combination.

Examples of the carboxylic anhydride component include tetracarboxylic anhydrides and tricarboxylic anhydrides, but are not limited to these acid anhydrides. Acid anhydride groups that react with amino groups and isocyanate groups and Any compound having a carboxyl group can be used, including its derivatives. Also, 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 polyetheramines, diamines having a carboxyl group, diamines having a phenolic hydroxyl group, 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 phenolic hydroxyl groups and carboxyl groups. Also, these amine components may be used alone or in combination.

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

(E) When an alkali-soluble polyamideimide resin is contained in the curable resin composition of the present invention, the alkali solubility (developability) of the polyamideimide resin and the mechanical properties of the cured product of the resin composition containing the polyamideimide resin From the viewpoint of improving the balance with other properties such as properties, the acid value (solid content acid value) is preferably 30 mgKOH/g or more, more preferably 30 mgKOH/g to 150 mgKOH/g, Especially preferred is 50 mg KOH/g to 120 mg KOH/g. Specifically, when the acid value is 30 mgKOH/g or more, the alkali solubility, that is, the developability, is improved, and the crosslink density with the thermosetting component after light irradiation is increased, resulting in sufficient development. You can get contrast. Further, by setting the acid value to 150 mgKOH/g or less, it is possible to suppress so-called heat fogging, especially in a PEB (POST EXPOSURE BAKE) step after light irradiation, which will be described later, and to increase the process margin.

Further, the molecular weight of the alkali-soluble polyamideimide resin is preferably 20,000 or less, more preferably 1,000 to 17,000, in consideration of developability and cured coating film properties. 2,000 to 15,000 is more preferred. When the molecular weight is 20,000 or less, the alkali-solubility of the unexposed area 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 area after the exposure/PEB process.

(E) When an alkali-soluble polyamideimide resin is contained in the curable resin composition of the present invention, in particular, a polyamide having a structure represented by the following general formula (4) and a structure represented by the following general formula (5) It is more preferable to use an imide resin from the viewpoint of further improving developability and improving flexibility and adhesion. Incidentally, the structure represented by the general formula (4) and the structure represented by the following general formula (5) may be contained in one molecule of (E) an alkali-soluble polyamideimide resin, (E) alkali-soluble may be included in a mixture of polyamidoimide resins.

(In the general formula (4), X ₁ is a residue of an aliphatic diamine (a) derived from a dimer acid having 24 to 48 carbon atoms (also referred to herein as “dimer diamine (a)”),
In general formula (5), X2 is a residue of aromatic diamine ( _b ) having a carboxyl group (also referred to herein as "carboxyl group-containing diamine (b)"). In general formulas (4) and (5), each Y is independently cyclohexane or an aromatic ring. )

By including the structure represented by the general formula (4) and the structure represented by the general formula (5), even when a mild alkaline solution such as a 1.0% by mass sodium carbonate aqueous solution is used, It can be a polyamide-imide resin excellent in alkali solubility that can dissolve also. Moreover, a cured product of a curable resin composition containing such a polyamideimide resin can have excellent dielectric properties.

The dimer diamine (a) can be obtained by reductively aminating a carboxyl group in a dimer of an aliphatic unsaturated carboxylic acid having 12 to 24 carbon atoms. That is, dimer diamine (a), which is an aliphatic diamine derived from dimer acid, is obtained by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid to form dimer acid, reducing this, and then aminating it. . As such an aliphatic diamine, commercially available products such as PRIAMINE 1073, 1074, and 1075 (manufactured by Croda Japan Co., Ltd., trade names), which are diamines having a skeleton of 36 carbon atoms, can be used. The dimer diamine (a) may be preferably derived from a dimer 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. is mentioned. The carboxyl group-containing diamine (b) may be composed of one type of compound, or may be composed of a plurality of types 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 (4) and the content of the structure represented by the general formula (5) in the polyamideimide resin is not limited. The content of dimer diamine (a) (unit: % by mass) is preferably 20 to 60 mass %, more preferably 30 to 50 mass %. In the present specification, the "content of dimer diamine (a)" refers to the charged amount of dimer diamine (a), which is positioned as one of raw materials for producing polyamide-imide resin, of the produced polyamide-imide resin. It means ratio to mass. Here, the "mass of the produced polyamide-imide resin" is the amount of water (H ₂ O) produced by imidization and carbon dioxide gas (CO ₂ ) is the value after subtracting the theoretical amount.

From the viewpoint of increasing the alkali solubility of the polyamide-imide resin, the portion represented by Y in the general formulas (4) and (5) preferably has a cyclohexane ring. From the viewpoint of improving the balance between the alkali solubility of the polyamideimide resin and other properties such as the mechanical properties of the cured product of the resin composition containing the polyamideimide resin, the aromatic ring and the cyclohexane ring in the portion represented by Y above. 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.

The method for producing the (E) alkali-soluble polyamide-imide resin is not limited, and it can be produced through an imidization step and an amidimidation step using a known and commonly used method.

In the imidization step, from dimer diamine (a), carboxyl group-containing diamine (b), and cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) and trimellitic anhydride (d) An imidized product is obtained by reacting one or two selected from the group consisting of:

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

Other diamines may be used together with dimer diamine (a) and carboxyl group-containing diamine (b), if desired. Specific examples of other diamines include 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]sulfone, 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'-diamino)diphenylmethane , (4,4′-diamino)diphenyl ether, (3,3′-diamino)diphenyl ether, hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, octadecamethylenediamine, Aliphatic diamines such as 4,4′-methylenebis(cyclohexylamine), isophoronediamine, 1,4-cyclohexanediamine and norbornenediamine are included.

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 should be 85/15 to 100/0. is preferred, 90/10 to 99/1 is more preferred, and 90/10 to 98/2 is even more preferred.

Amount of diamine compound (specifically, dimer diamine (a), carboxyl group-containing diamine (b), and other diamines used as necessary) used to obtain imidized product and acid anhydride (Specifically, it means one or two selected from the group consisting of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) and trimellitic anhydride (d). ) is not limited. The amount of the acid anhydride used is preferably such that the molar ratio with respect to the amount of the diamine compound used is 2.0 or more and 2.4 or less, and the amount is such that the molar ratio is 2.0 or more and 2.2 or less. It is more preferable to have

In the amidimidation step, the imidized product obtained in the above imidization step is reacted with a diisocyanate compound to obtain a polyamideimide resin containing a substance having a structure represented by the following general formula (6).

A specific type of diisocyanate compound is not limited. The diisocyanate compound may be composed of one type of compound, or may be composed of a plurality of types of compounds.

Specific examples of diisocyanate compounds include 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate aromatic diisocyanates such as isocyanate and 2,4-tolylene dimer; aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate and norbornene diisocyanate; (E) From the viewpoint of improving both the alkali solubility of the alkali-soluble polyamideimide resin and the light transmittance of the polyamideimide resin, the diisocyanate compound preferably contains an aliphatic isocyanate, and the diisocyanate compound is an aliphatic isocyanate. It is more preferable to have

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

（上記一般式（６）中、Ｘはそれぞれ独立にジアミン残基（ジアミン化合物の残基）、Ｙはそれぞれ独立に芳香環またはシクロヘキサン環、Ｚはジイソシアネート化合物の残基である。ｎは自然数である。）で示される構造を有する物質を含む。 The polyamideimide resin thus produced has the following general formula (6)

(In the above general formula (6), X is each independently a diamine residue (diamine compound residue), Y is each independently an aromatic ring or cyclohexane ring, Z is a residue of a diisocyanate compound. n is a natural number. ) includes substances having the structure shown in

(E) When an alkali-soluble polyamideimide resin is blended, from the viewpoint of improving heat resistance and developability, the mixing ratio of (E) the alkali-soluble polyamideimide resin and (A) the alkali-soluble polyimide resin The mass ratio can be 98:2 to 50:50, preferably 95:5 to 50:50, more preferably 95:5 to 70:30.
The curable resin composition of the present invention may further contain the following components, if necessary.

[Polymer resin]
The curable resin composition of the present invention can be blended with a known and commonly used polymer resin for the purpose of improving the flexibility and dryness to the touch of the resulting cured product. Examples of such polymer resins include polyester-based polymers, phenoxy resin-based polymers, polyvinylacetal-based polymers, polyvinyl butyral-based polymers, polyamide-based polymers, elastomers, and the like. Such polymer resins may be used singly or in combination of two or more.

[Inorganic filler]
The curable resin composition of the present invention can contain an inorganic filler 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, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, and Neuburg Silicious Earth.

[Coloring agent]
The curable resin composition of the present invention can contain known and commonly used colorants such as red, orange, blue, green, yellow, white and black. Any of pigments, dyes, and dyes may be used as such a coloring agent.

[Organic solvent]
The curable resin composition of the present invention can be blended with an organic solvent for preparing the resin composition or for adjusting the viscosity for application to a substrate or carrier film. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum solvents. Such organic solvents may be used singly or as a mixture of two or more.

[Other ingredients]
The curable resin composition of the present invention may further contain components such as mercapto compounds, adhesion promoters, antioxidants and ultraviolet absorbers, if necessary. Known and commonly used materials can be used as these materials.

In addition, known and commonly used thickeners such as finely divided silica, hydrotalcite, organic bentonite, and montmorillonite, antifoaming agents and/or leveling agents such as silicone-based, fluorine-based, and polymer-based agents, silane coupling agents, and rust inhibitors. Known and commonly used additives such as these can be blended.

<Laminated structure>
According to the curable resin composition of the present invention, it is possible to form a resin layer from the curable resin composition and obtain a laminate structure in which at least one surface of the resin layer is supported or protected by a film.

The resin layer may be a single layer, or may have a laminated structure of two or more resin layers. In the case of a laminated structure of two or more resin layers, for example, a resin layer formed of the curable resin composition of the present invention may be laminated, or a resin layer formed of the curable resin composition of the present invention. and a resin layer formed of a curable resin composition not according to the present invention.

When the latter laminated structure is adopted, the laminated structure includes, for example, a resin layer (A) provided on a substrate such as a flexible printed wiring board, a resin layer (B) provided on the resin layer (A), At least one side of the resin layer having a laminated structure of is supported or protected by the film. The resin layer (A) is made of, for example, an alkali-developable resin composition containing an alkali-soluble resin and a heat-reactive compound.

The laminated structure can be manufactured, for example, as follows.

That is, first, on a carrier film (support film), the curable resin composition of the present invention constituting the resin layer is diluted with an organic solvent to adjust the viscosity to an appropriate value. Apply by method. When the resin layer has a laminated structure, the coating operation is repeated with or without changing the resin composition to be applied. Thereafter, it is usually dried at a temperature of 50 to 130° C. for 1 to 30 minutes to prepare a laminated structure in which a dry coating film of a resin layer in a B-stage state (semi-cured state) is formed on a carrier film. be able to. The resin layer of this laminated structure is a so-called dry film. 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 dry coating film. As the carrier film and the cover film, conventionally known plastic films can be appropriately used. Regarding the cover film, when the cover film is peeled off, the adhesion force between the resin layer and the carrier film should be smaller. preferable. The thickness of the carrier film and cover film is not particularly limited, but is generally selected appropriately within the range of 10 to 150 μm.

<Cured product>
The cured product of the present invention is obtained by curing the curable resin composition of the present invention or the resin layer of the laminated structure.

<Electronic parts>
The curable resin composition of the present invention and the resin layer of the laminate structure can be effectively used for electronic parts such as flexible printed wiring boards. Specifically, a layer of the curable resin composition of the present invention or a resin layer of a laminated structure is formed on a flexible printed wiring base material, patterned by light irradiation, and an insulation formed by forming a pattern with a developer. Examples include flexible printed wiring boards having a cured film.

A method for manufacturing a flexible printed wiring board will be specifically described below.

<Method for manufacturing flexible printed wiring board>
An example of manufacturing a flexible printed wiring board using the curable resin composition of the present invention or the resin layer of the laminated structure will be described below. That is, a step of forming a resin layer by applying the curable resin composition of the present invention on a flexible printed wiring substrate on which a conductive circuit is formed, or by attaching the resin layer of the laminated structure (layer forming step); Manufacturing including a step of patternwise irradiating the resin layer with active energy rays (exposure step) and a step of alkali developing the exposed resin layer to form a patterned resin layer image (development step). The method. Further, if necessary, after alkali development, further photocuring or heat curing (post-curing step) is performed to completely cure the resin layer, form a cured film, and obtain a highly reliable flexible printed wiring board. be able to.

Moreover, the production of a flexible printed wiring board using the curable resin composition of the present invention or the resin layer of the laminated structure can also be carried out according to other procedures. That is, a step of forming a resin layer by applying the curable resin composition of the present invention on a flexible printed wiring substrate on which a conductive circuit is formed, or by attaching the resin layer of the laminated structure (layer forming step); A step of irradiating the resin layer with an active energy ray in a pattern (exposure step), a step of heating the resin layer after exposure (heating (PEB) step), and an alkaline development of the resin layer after heating to form a pattern. It is a manufacturing method including a step of forming a cured resin layer image (developing step). Further, if necessary, after alkali development, further photocuring or heat curing (post-curing step) is performed to completely cure the resin layer, form a cured film, and obtain a highly reliable flexible printed wiring board. be able to.

The present invention is not limited to the configurations and examples of the above embodiments, and various modifications are possible within the scope of the gist of the invention.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited only to these Examples. In addition, "part" shall mean the mass part of solid content unless there is particular notice below.

((A) Synthesis of alkali-soluble polyimide resin)
[Synthesis Example 1]
22.4 g of 3,3′-diamino-4,4′-dihydroxydiphenylsulfone, 2,2′-bis[4 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 were added, Under nitrogen atmosphere, the mixture was stirred at room temperature and 100 rpm for 4 hours. Next, 20 g of toluene was added, and the mixture was stirred for 4 hours at a silicone bath temperature of 180° C. and 150 rpm while toluene and water were distilled off to obtain a polyimide resin solution (PI-1) having phenolic hydroxyl groups and carboxyl groups.

The obtained resin (solid content) had an acid value of 18 mg KOH, an Mw of 10,000, and a hydroxyl equivalent of 390.

((B) Synthesis of cellulose derivative)
[Synthesis Example 1]
A flask equipped with a stirrer, a thermometer and a reflux condenser was charged with 64 g of methyl ethyl ketone and 16 g of CAB-553-0.4 (cellulose acetate derivative, manufactured by Eastman Chemical Co.) and stirred at 75° C. for 1 hour. Then, a mixture obtained by premixing 15 g of methyl methacrylate and 1 g of benzoyl peroxide was added dropwise over 3 hours. After the dropwise addition was completed, a mixture obtained by previously mixing 0.5 g of benzoyl peroxide and 5 g of methyl ethyl ketone was added dropwise over 1 hour while maintaining the temperature at 75°C. Stirring was further continued at 75° C. for 3 hours and then cooled. 61 g of methyl ethyl ketone was added to the mixture and stirred to obtain a resin solution (CA-1). The content of resin solution CA-1 after heating was 20.0% by mass.

[Synthesis Example 2]
A flask equipped with a stirrer, a thermometer and a reflux condenser was charged with 64 g of methyl ethyl ketone and 16 g of CAB-553-0.4 (cellulose acetate derivative, manufactured by Eastman Chemical Co.) and stirred at 75° C. for 1 hour. Then, a mixture obtained by premixing 15 g of glycidyl methacrylate and 1 g of benzoyl peroxide was added dropwise over 3 hours. After the dropwise addition was completed, a mixture obtained by previously mixing 0.5 g of benzoyl peroxide and 5 g of methyl ethyl ketone was added dropwise over 1 hour while maintaining the temperature at 75°C. Stirring was further continued at 75° C. for 3 hours and then cooled. 61 g of methyl ethyl ketone was added to the mixture and stirred to obtain a resin solution (CA-2). The content of resin solution CA-2 after heating was 20.0% by mass.

((E) Synthesis of alkali-soluble polyamideimide resin)
[Synthesis Example 1]
6.98 g of 2,2′-bis[4-(4-aminophenoxy)phenyl]propane, 3,5-diaminobenzoic acid and 3.5-diaminobenzoic acid were placed in a four-necked 300 mL flask equipped with a nitrogen gas inlet 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.

Next, 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., and after removing the water generated together with the toluene, the mixture was held for 3 hours and cooled to room temperature to obtain an imidized compound solution.

9.61 g of trimellitic anhydride and 17.45 g of trimethylhexamethylene diisocyanate were added to the imidized product solution obtained, and the mixture was maintained at a temperature of 160° C. for 32 hours. Thus, an alkali-soluble polyamide-imide resin solution (A-1) containing carboxyl groups was obtained. The solid content was 40.1% by mass and the acid value was 83 mgKOH/g.

[Synthesis Example 2]
In a four-necked 300 mL flask equipped with a nitrogen gas inlet tube, a thermometer, and a stirrer, an aliphatic diamine derived from a dimer acid having 36 carbon atoms as a dimer diamine (a) (manufactured by Croda Japan, product name PRIAMINE 1075) 28 0.61 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 anhydride (c) and 3.07 g (0.016 mol) of trimellitic anhydride (d) were added, and the mixture was stirred at room temperature for 30 minutes. held. Further, 30 g of toluene was charged, the temperature was raised to 160° C., water generated together with toluene was removed, the mixture was held for 3 hours, and the mixture was cooled to room temperature to obtain a solution containing an imidized compound.

14.30 g (0.068 mol) of trimethylhexamethylene diisocyanate as a diisocyanate compound was added to the solution containing the obtained imidized product, maintained at a temperature of 160° C. for 32 hours, and diluted with 21.4 g of cyclohexanone. , a solution (A-2) containing an alkali-soluble polyamide-imide resin containing carboxyl groups was obtained. The resulting polyamideimide 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 dimer diamine (a) content of 40.0% by mass.

<1. Preparation of curable resin compositions of Examples 1 to 8 and Comparative Examples 1 to 3>
According to the component composition shown in Table 1 below, the materials of the curable resin compositions of Examples 1 to 8 and Comparative Examples 1 to 3 were each blended, premixed with a stirrer, and then kneaded with a three-roll mill. Then, each curable resin composition for forming a resin layer was prepared. In addition, the value in Table 1 is the mass part of solid content, unless there is particular notice.

For each curable resin composition, as shown below, a resin layer (dry coating film) in a B-stage state (semi-cured state) of each curable resin composition is formed, and developability (alkali solubility) is evaluated. evaluated. Furthermore, as described later, a flexible printed wiring board having a cured product of this resin layer was formed, and heat resistance (solder heat resistance), gold plating resistance (chemical resistance), flexibility and adhesion were evaluated. Table 1 shows the results.

<2. Formation of Resin Layer>
A flexible printed wiring substrate on which a circuit with a copper thickness of 18 μm is formed was prepared and pretreated using CZ-8100 manufactured by MEC. After that, each curable resin composition obtained in Examples 1 to 8 and Comparative Examples 1 to 3 was applied to the pretreated flexible printed wiring substrate so that the film thickness after drying was 30 μm. . Then, it was dried at 90° C. for 30 minutes in a hot air circulating drying oven to form a B-stage (semi-cured) resin layer (dry coating film).

<3. Preparation of Evaluation Board>
First, an exposure device (HMW-680-GW20) equipped with a metal halide lamp is applied to the resin layer (dried coating film) in the B stage state (semi-cured state) on each flexible printed wiring substrate on which the resin layer is formed as described above. (manufactured by Oak Manufacturing Co., Ltd.), pattern exposure was performed through a negative mask at 300 mJ/cm ² so as to form an opening with a diameter of 200 μm. After that, a PEB process was performed at 90° C. for 30 minutes, followed by development (30° C., 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) for 60 seconds, and curing by heat curing at 150° C. for 60 minutes. A flexible printed wiring board (evaluation board) having a resin layer (cured coating film) formed thereon was produced.

<4. Evaluation of developability (alkali solubility)>
<2. Formation of Resin Layer> First, an exposure apparatus (HMW-680- GW20 (manufactured by Oak Manufacturing Co., Ltd.), pattern exposure was performed through a negative mask at 300 mJ/cm ² so as to form an opening with a diameter of 200 μm. 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 solution of sodium carbonate at 30° C. for 1 minute to develop, the state of pattern formation was observed, and developability (alkali solubility) was evaluated. Evaluation criteria are as follows.

◯: The exposed area exhibited developability, the unexposed area exhibited developability, and pattern formation was good.
x: The unexposed area exhibits developability, but resolution pattern formation is poor (insufficient resolution).

<5. Evaluation of heat resistance (solder heat resistance)>
<3. Preparation of evaluation substrate> A rosin-based flux is applied to the evaluation substrate prepared as described in, and immersed in a solder bath set to 260 ° C. in advance for 20 seconds (10 seconds x 2 times) to form a cured coating film. Blistering and peeling were observed, and heat resistance (solder heat resistance) was evaluated. Evaluation criteria are as follows.
⊚: There was no swelling or peeling even after being immersed twice for 10 seconds.
◯: No swelling or peeling occurred even after immersion for 10 seconds×1 time, but peeling occurred in the second immersion.
x: Swelling and peeling occurred when immersed once for 10 seconds.

<6. Evaluation of Gold Plating Resistance (Chemical Resistance)>
<3. Production of Evaluation Substrate>, evaluation was performed by the following method using an evaluation substrate manufactured as described above.

Using commercially available electroless nickel plating baths and electroless gold plating baths, the substrates for evaluation were plated with 5 μm of nickel and 0.05 μm of gold at 80 to 90° C. The substrate and the cured coating were observed. Plating resistance (chemical resistance) was evaluated. Evaluation criteria are as follows.

◯: No permeation between the substrate and the cured coating film.
Δ: Penetration is confirmed between the substrate and the cured coating film.
x: Part of the cured coating film is peeled off.

<7. Flexibility (MIT test)>
<3. Preparation of Evaluation Board> Using each evaluation board prepared as described in MIT folding fatigue tester D type (manufactured by Toyo Seiki Seisakusho), the film is regarded as paper in accordance with JIS P8115. A test was performed to evaluate flexibility. Specifically, as shown in FIG. 1, the test piece 1 is attached to the device, and a load F (0.5 kgf) is applied. Bending was performed at 135 degrees and a speed of 175 cpm, and the number of reciprocating bendings (times) until breakage was measured. The test environment was 25° C., and the radius of curvature was R=0.38 mm. Evaluation criteria are as follows.

A: It was bent 200 times or more, and the cured coating film at the bent portion did not crack.
◯: It was bent 170 to 199 times, and similarly no crack occurred.
Δ: It was bent 150 to 169 times, and no crack was generated.
x: Cracks occurred when the number of times of bending was 149 or less.

<8. Adhesion>
<2. Formation of resin layer> First, an exposure device equipped with a metal halide lamp is applied to the resin layer (dried coating film) in the B stage state (semi-cured state) on each flexible printed wiring substrate on which the resin layer is formed as described in (HMW-680-GW20: manufactured by ORC Manufacturing Co., Ltd.), solid exposure was performed at 300 mJ/cm ² through a negative mask. After that, a PEB process was performed at 90° C. for 30 minutes, followed by development (30° C., 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) for 60 seconds, and curing by heat curing at 150° C. for 60 minutes. A flexible printed wiring board (evaluation board) having a resin layer (cured coating film) formed thereon was produced.

The obtained evaluation substrates were cut into 2 cm squares, 10 sheets were stacked, left at temperatures of 20, 30, 40 and 60° C. for 72 hours, and then the presence or absence of sticking was checked. Evaluation criteria are as follows.

◎: No sticking at 60 ° C. ○: No sticking at 40 ° C. or lower, but slight sticking at 60 ° C. △: No sticking at 30 ° C. or lower, but sticking at 40 ° C. or higher ×: Any temperature But you can see the sticking

Details of the components in Table 1 are as follows.

PI-1: Alkali-soluble polyimide resin solution produced by [Synthesis Example 1] of ((A) synthesis of alkali-soluble polyimide resin) described above A-1: Alkali-soluble polyimide resin solution A-1: ((E) alkali-soluble Polyamideimide resin-containing solution prepared by [Synthesis Example 1] in Synthesis of polyamideimide resin) A-2: Produced by [Synthesis Example 2] in ((E) Synthesis of alkali-soluble polyamideimide resin) described above Polyamideimide resin-containing solution P7-532: Polyurethane acrylate, acid value 47 mgKOH/g (manufactured by Kyoeisha Chemical Co., Ltd.)
IRGACURE OXE02: oxime photobase generator (manufactured by BASF)
CAB-553-0.4: Cellulose acetate derivative, number average molecular weight 20,000, 20 wt% DPM solution (manufactured by Eastman Chemical Co.) (parts in Table 1 indicate mass parts of solid content of 20 wt% DPM solution) )
CAB-504-0.2: Cellulose acetate derivative, number average molecular weight 15,000, 20 wt% DPM solution (manufactured by Eastman Chemical Co.) (parts in Table 1 indicate mass parts of solid content of 20 wt% DPM solution) )
CA-1: CAB-553-0.4 modified with methyl methacrylate, number average molecular weight 24,000, 20 wt% MEK solution (table The number of parts in 1 indicates the mass part of the solid content of the 20 wt% MEK solution)
CA-2: CAB-553-0.4 modified with glycidyl methacrylate, number average molecular weight 25,000, 20 wt% MEK solution (table The number of parts in 1 indicates the mass part of the solid content of the 20 wt% MEK solution)
jER828: bisphenol A type epoxy resin, epoxy equivalent 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)

As shown in Table 1, from the comparison between Examples and Comparative Examples, the curable resin composition contains (A) an alkali-soluble polyimide resin, (C) a thermosetting compound, and (D) a photobase generator. By including (B) a cellulose derivative, the formed resin layer has good developability, and the resin layer after curing not only has excellent heat resistance, gold plating resistance, and flexibility, but also has been confirmed to have little sticking. rice field.

Further, from the comparison between Examples 1-2 and Examples 3-8, the heat resistance is further improved when the (E) alkali-soluble polyamideimide resin (A) is blended more than the alkali-soluble polyimide resin. was shown. Further, from the comparison between Example 3 and Examples 7 and 8, by using the cellulose derivative (B) containing the group represented by the formula (2), the sticking property is further reduced, that is, sticking It was found that the evaluation result of the sex became better. Further, from the comparison between Example 3 and Example 6, it is found that (E) as the alkali-soluble polyamideimide resin, a polyamideimide resin having a structure represented by the formula (4) and a structure represented by the formula (5) is used. It was found that the flexibility and sticking property were also improved.

Claims (7)

(A) an alkali-soluble polyimide resin;
(B) a cellulose derivative;
(C) a thermosetting compound;
(D) a curable resin composition comprising a photobase generator; 2. The curable resin composition according to claim 1, wherein the (A) alkali-soluble polyimide resin has a carboxyl group. 3. The curable resin composition according to claim 2, wherein the (A) alkali-soluble polyimide resin has a carboxyl group and a phenolic hydroxyl group. 2. The curable resin composition according to claim 1, further comprising (E) an alkali-soluble polyamide-imide resin. The curable resin composition according to any one of claims 1 to 4, wherein (C) the thermosetting compound is an epoxy resin. A cured product obtained from the curable resin composition according to claim 1 . An electronic component comprising an insulating film made of the cured product according to claim 6 .

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