KR20230163369A - Curable resin compositions, laminated structures, cured products, and electronic components - Google Patents

Abstract

[Problem] To provide a curable resin composition that has good resolution of the obtained dried coating film and has small sticking properties even when the cured product after heat curing is laminated and stored in a high temperature environment.
[Solution] It is a curable resin composition that is capable of alkali development and forms a cured film through exposure and heat treatment. When a dry coating film with a thickness of 2 to 100 μm is formed from this curable resin composition, the arithmetic average roughness Ra of the dry coating film is less than 0.1 μm, and the arithmetic average roughness Ra of the cured film after heat curing of the dry coating film is 0.1 μm or more. It becomes less than 1㎛. According to the curable resin composition of the present invention, the resolution of the obtained dried coating film is good, and even when the cured product after heat curing is laminated and stored in a high temperature environment, it has the characteristic of small sticking.

Description

Curable resin compositions, laminated structures, cured products, and electronic components

The present invention relates to an electronic component having a curable resin composition, a laminated structure of a resin layer formed from the curable resin composition, a cured product thereof, and an insulating film containing the cured product. In particular, it is capable of alkali development, exposure and heat treatment. It relates to an electronic component having a curable resin composition that forms a cured film, a laminated structure of a resin layer formed from the curable resin composition, a cured product thereof, and an insulating film containing the cured product.

Conventionally, as a protective film for flexible printed wiring boards, a non-photosensitive resin structure made by applying a thermosetting adhesive to a film such as polyimide has been used. As a method of pattern processing such a non-photosensitive resin structure and forming it on a flexible printed wiring board, a method of forming a hole by punching and then heat-compressing the structure on a flexible printed wiring board has been conventionally adopted. Alternatively, a method of pattern printing a solvent-soluble thermosetting resin composition directly on a flexible printed wiring board and heat curing to form a pattern has also been taken. In particular, polyimide film has been used as a suitable material for flexible printed wiring boards because it is flexible and has excellent heat resistance, mechanical properties, and electrical properties (see, for example, Patent Document 1).

However, in the above-described conventional method, the shape of the edge of the pattern is lost due to spread of the resin during application or heat compression, so formation of fine patterns required for miniaturization of wiring and miniaturization of chip components mounted on flexible printed wiring boards, etc. was difficult.

Publication No. WO2012/133665

On the other hand, it is also conceivable to apply photosensitive solder resist, which is known as a permanent protective film for circuits capable of fine processing, as a cover layer for flexible printed wiring boards. Photosensitive solder resists in flexible printed wiring boards require low crosslinking density to provide flexibility. Since flexible substrates are thin and easily bent, they are often stored and transported by stacking several sheets and fixing them. It is exposed to high temperatures due to its storage environment and transportation environment, and when a photosensitive solder resist is applied to the cover lay, the area that protects the flexible printed wiring board is expanded, so the coating films formed on the substrate are adhered to each other due to low crosslinking density. There are cases.

Additionally, in recent years, there has been an increasing demand for thinner films even in fields that use rigid substrates. Not only flexible substrates, but also thin substrates such as rigid substrates with a thickness of 0.1 mm, the phenomenon of coating films sticking together may similarly occur.

To solve this problem, if the surface roughness of the coating film is increased, the contact surface area becomes small and sticking does not occur. However, when an attempt is made to pattern a coating film with high surface roughness by photolithography, halation occurs on the surface of the coating film, and sufficient resolution cannot be obtained.

The first object of the present invention in consideration of the above problems is to provide a curable resin composition that has good resolution of the dried coating film, good flexibility of the obtained cured product, and has the characteristic of small sticking when laminated and stored. there is.

In addition, the second object of the present invention in consideration of the above problems is to provide a dry coating film that has good developability, the obtained cured product has good heat resistance and flexibility, and has the property of having a small sticking effect when the obtained cured product is laminated and stored. The object is to provide a curable resin composition.

The present inventors conducted intensive studies to achieve the above first objective. As a result, by using a curable resin composition that can keep the surface roughness (arithmetic average roughness) small at the time of drying the coating film and increasing the surface roughness (arithmetic average roughness) after heat curing, high resolution of the dry coating film and thermosetting film can be achieved. It was discovered that both flexibility and low stickability could be achieved, and the present invention was completed. In addition, in this specification, resolution refers to the ability to express the details of the image obtained when the resin layer containing the curable resin composition of the present invention is exposed to light and subjected to alkali development.

That is, the first object of the present invention is,

A curable resin composition capable of alkali development and forming a cured film by exposure and heat treatment,

When a dry coating film with a thickness of 2 to 100 μm is formed from the curable resin composition, the arithmetic average roughness Ra of the dry coating film is less than 0.1 μm, and the arithmetic average roughness Ra of the cured film after heat curing of the dry coating film is 0.1. It has been found that this can be achieved by a curable resin composition (hereinafter also referred to as the curable resin composition of the first aspect of the present invention) characterized by being ㎛ or more and 1 ㎛ or less.

In addition, in this specification, resolution refers to the detailed representation of the image obtained when the resin layer containing the curable resin composition of the first aspect of the present invention is pattern exposed and subjected to alkali development.

In addition, the curable resin composition of the first aspect of the present invention has, when a dry coating film with a thickness of 2 to 100 ㎛ is formed from the curable resin composition, the arithmetic mean roughness Ra of the dry coating film is less than 0.05 ㎛, and the above It is preferable that the arithmetic mean roughness Ra of the cured film after thermal curing of the dried coating film is 0.1 μm or more and 0.5 μm or less.

Furthermore, it is preferable to contain (A) an alkali-soluble polyamidoimide resin, (B) a photobase generator, (C) a thermosetting compound, and (D) a cellulose derivative.

Additionally, it is preferable that the thermosetting compound (C) is an epoxy resin.

Furthermore, the first object of the present invention is a laminate structure in which at least one side of a resin layer formed from the curable resin composition of the present invention is supported or protected by a film;

This can also be achieved with an electronic component having an insulating film containing the curable resin composition of the present invention or the cured product of the resin layer of the laminated structure of the present invention and the cured product of the present invention.

Additionally, the present inventors conducted intensive studies to achieve the above-mentioned second objective. As a result, it was found that by adding a cellulose derivative to the curable resin composition and using a predetermined blend containing an alkali-soluble polyimide resin, the adhesion between the obtained cured products became smaller, leading to the completion of the present invention. .

That is, the second object of the present invention is,

(A) an alkali-soluble polyamideimide resin,

(B) a photobase generator,

(C) a thermosetting compound,

(D) Cellulose derivatives

It has been found that this can be achieved by a curable resin composition characterized by containing (hereinafter also referred to as the curable resin composition of the second aspect of the present invention).

Moreover, it is preferable that (A) the alkali-soluble polyamideimide resin has a carboxyl group, and it is more preferable that the (A) alkali-soluble polyamideimide resin has a carboxyl group and a phenolic hydroxyl group.

Moreover, it is preferable that the curable resin composition of the second aspect of the present invention further contains (E) an alkali-soluble polyimide resin.

Furthermore, it is preferable that the thermosetting compound (C) is an epoxy resin.

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

According to the curable resin composition of the first aspect of the present invention, the resolution of the obtained dried coating film is good, the obtained cured product after heat curing has good flexibility, and the cured product can be stuck even when laminated and stored in a high temperature environment. has a small characteristic.

In addition, the developability of the dry film of the curable composition of the second aspect of the present invention is good, and the cured product obtained by the curable composition of the second aspect of the present invention has good heat resistance and flexibility, and can be stored by laminating. In some cases, the adhesive has the characteristic of being small.

Figure 1 is an explanatory diagram of an MIT test performed using the evaluation board manufactured in the example as a test piece.

<Curable resin composition of the first aspect of the present invention>

The curable resin composition of the first aspect of the present invention,

A curable resin composition capable of alkali development and forming a cured film by exposure and heat treatment,

When a dry coating film with a thickness of 2 to 100 μm is formed from a curable resin composition, the arithmetic average roughness Ra of the dry coating film is less than 0.1 μm, and the arithmetic average roughness Ra of the cured film after heat curing of the dry coating film is 0.1 μm or more. It becomes less than 1㎛.

The curable resin composition of the first aspect of the present invention is capable of alkali development, and in order to form a cured film by exposure and heat treatment, its constituent component is a compound having an alkali-soluble functional group (hereinafter also referred to as an alkali-soluble group). (hereinafter also referred to as an alkali-soluble compound), (B) a photobase generator and (C) a thermosetting compound described later.

Among these, the photobase generator (B) functions as a catalyst for the addition reaction between the alkali-soluble compound and the (C) thermosetting compound by changing the molecular structure or chopping the molecule upon irradiation of light such as ultraviolet rays or visible light. do.

Examples of alkali-soluble compounds include compounds having a phenolic hydroxyl group, compounds having a carboxyl group, and compounds having a phenolic hydroxyl group and a carboxyl group. Preferably, the alkali-soluble compound is the alkali-soluble polyamidoimide resin (A) described later. Among these, (A) as the alkali-soluble polyamideimide resin, it is preferable to use a polyamideimide resin having a structure represented by the general formula (1) described later and a structure represented by the general formula (2) below.

When a dry coating film with a thickness of 2 to 100 ㎛, more preferably 3 to 80 ㎛ from the viewpoint of improving resolution, is formed from the curable resin composition of the first aspect of the present invention, the arithmetic mean roughness Ra of this dry coating film is 0.1. It is less than ㎛, preferably less than 0.05 ㎛, and the arithmetic mean roughness Ra of the cured film after thermal curing of the dried coating film is 0.1 ㎛ or more and 1 ㎛ or less, preferably 0.1 ㎛ or more and 0.5 ㎛ or less.

When the arithmetic mean roughness Ra of the dry coating film is less than 0.1 μm, diffuse reflection of light irradiated to the coating film during exposure is suppressed, resulting in good resolution. Additionally, after thermal curing, the arithmetic mean roughness Ra of the cured film becomes 0.1 μm or more and 1 μm or less, causing small irregularities to occur on the cured film. The presence of these irregularities reduces the contact area between the cured films arranged in a laminated manner, contributing to the deterioration of the adhesiveness.

In the state of the dry coating film before thermal curing, the unevenness of the dry coating film is small, and in the cured film after thermal curing, the phenomenon of increasing irregularities on the cured film is that the curable resin composition of the present invention is a thermosetting compound or alkali soluble compound (C). It is thought to be caused by the inclusion of polymer components that have different compatibility with the compounds. That is, it is presumed that it occurs when polymer components that were dispersed in the dry coating film before thermal curing migrate to the film surface during the thermal curing reaction.

As this polymer component, it is preferable to mix (D) a cellulose derivative.

The curable resin composition of the first aspect of the present invention preferably contains (A) an alkali-soluble polyamideimide resin, (B) a photobase generator, (C) a thermosetting compound, and (D) a cellulose derivative. do.

<Curable resin composition of the second aspect of the present invention>

The curable resin composition of the second aspect of the present invention,

(A) an alkali-soluble polyamideimide resin,

(B) a photobase generator,

(C) a thermosetting compound,

(D) Cellulose derivatives

Contains

Moreover, it is preferable that the curable resin composition of the second aspect of the present invention contains (E) an alkali-soluble polyimide resin.

Furthermore, it is preferable that the thermosetting compound (C) is an epoxy resin.

[(A) Alkali-soluble polyamideimide resin]

(A) Alkali-soluble polyamidoimide resin is a preferred example of the alkali-soluble photocurable compound. (A) The alkali-soluble polyamideimide resin contains an alkali-soluble group (at least one of a phenolic hydroxyl group and a carboxyl group). The curable resin composition of the first aspect of the present invention preferably contains (A) an alkali-soluble polyamideimide resin, and the curable resin composition of the second aspect of the present invention preferably contains (A) an alkali-soluble polyamideimide resin. Contains resin.

Such alkali-soluble polyamidoimide resins include, for example, resins obtained by reacting a carboxylic acid anhydride component and an amine component to obtain an imidide, and then reacting the obtained imidate with an isocyanate component. Here, the alkali-soluble group is introduced by using an amine component having a carboxyl group or a phenolic hydroxyl group. Additionally, imidization may be performed by thermal imidation, chemical imidation, or a combination of these.

Examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydride and tricarboxylic acid anhydride, but are not limited to these acid anhydrides. Any compound having an acid anhydride group and a carboxyl group that reacts with an amino group or an isocyanate group may be used. It can be used including derivatives. Additionally, these carboxylic acid anhydride components may be used individually or in combination.

As the amine component, diamines such as aliphatic diamine and aromatic diamine, polyhydric amines such as aliphatic polyetheramine, diamines having a carboxyl group, diamines having a phenolic hydroxyl group, etc. 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 type of functional group of a phenolic hydroxyl group or a carboxyl group. Additionally, these amine components may be used individually or in combination.

As the isocyanate component, diisocyanates such as aromatic diisocyanates and their isomers and multimers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers, and other general-purpose diisocyanates can be used, but are not limited to these isocyanates. . In addition, these isocyanate components may be used individually or in combination.

(A) When an alkali-soluble polyamideimide resin is included in the curable resin composition of the present invention, the alkali solubility (developability) of the polyamideimide resin, the mechanical properties of the cured product of the resin composition containing the polyamideimide resin, etc. From the viewpoint of maintaining a good balance of other characteristics, the acid value (solid 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. It is especially desirable to do so. Specifically, by setting this acid value to 30 mgKOH/g or more, alkali solubility, that is, developability becomes good, and furthermore, the crosslinking density with the heat-curing component after light irradiation increases, and sufficient development contrast can be obtained. Furthermore, by setting the acid value to 150 mgKOH/g or less, so-called thermal blurring can be suppressed, especially in the PEB (POST EXPOSURE BAKE) process after light irradiation, which will be described later, and the process margin is increased.

In addition, considering the developability and cured film properties, the molecular weight of the alkali-soluble polyamidoimide resin (A) is preferably 20,000 or less, more preferably 1,000 to 17,000, and even more preferably 2,000 to 15,000. . If the molecular weight is 20,000 or less, the alkali solubility of the unexposed area increases and developability improves. On the other hand, if the molecular weight is 1,000 or more, sufficient development resistance and cured material properties can be obtained in the exposed area after the exposure/PEB process.

(A) When an alkali-soluble polyamideimide resin is included in the curable resin composition of the present invention, in particular, a polyamideimide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2) It is more preferable to use because it further improves developability and also improves flexibility and stickability. In addition, the structure represented by General Formula (1) and the structure represented by General Formula (2) below are not limited to the case where they are contained in one molecule of (A) alkali-soluble polyamidoimide resin, and (A) alkali soluble polyamideimide resin. It just needs to be contained in a soluble polyamidoimide resin.

(In General Formula ( ₁ ),

In General Formula ( ₂ ), In general formulas (1) and (2), Y is each independently cyclohexane or an aromatic ring.)

By comprising the structure represented by the general formula (1) and the structure represented by the general formula (2), the product has excellent alkali solubility, capable of dissolving even when a mild alkaline solution such as a 1.0% by mass aqueous solution of sodium carbonate is used. It can be made with polyamideimide resin. Additionally, a cured product of a curable resin composition containing such polyamideimide resin can have excellent dielectric properties.

Dimeric diamine (a) can be obtained by reductive amination of the 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, for example, by polymerizing unsaturated fatty acids such as oleic acid and linoleic acid to form dimer acid, reducing this, and then amination. As such aliphatic diamine, for example, commercially available products such as PRIAMINE 1073, 1074, and 1075 (manufactured by Croda Japan, brand name), which are diamines having a skeleton of 36 carbon atoms, can be used. In some cases, the dimer diamine (a) is preferably derived from a dimer acid having 28 to 44 carbon atoms, and in some cases, it is more preferable to be derived from a dimer acid with 32 to 40 carbon atoms.

Specific examples of carboxyl group-containing diamine (b) include 3,5-diaminobenzoic acid, 3,4-diaminobenzoic acid, 5,5'-methylenebis(anthranilic acid), benzidine-3,3'-dicarboxylic acid, etc. can be mentioned. The carboxyl group-containing diamine (b) may be composed of one type of compound or may be composed of multiple 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).

In the polyamideimide resin, the relationship between the content of the structure represented by the general formula (1) and the content of the structure represented by the general formula (2) is not limited. From the viewpoint of improving the balance of other properties such as the alkali solubility of the polyamideimide resin and the mechanical properties of the cured product of the curable resin composition containing the polyamideimide resin, the content (unit: mass%) of dimer diamine (a) is 20 to 60 mass% is preferable, and 30 to 50 mass% is more preferable. In this specification, “content of dimer diamine (a)” refers to the mass of the produced polyamideimide resin of the input amount of dimer diamine (a), which can be positioned as one of the raw materials when producing polyamideimide resin. It means the ratio for Here, the “mass of the produced polyamideimide resin” is calculated from the input amount of all raw materials for producing the polyamideimide resin, water (H ₂ O) generated from imidization and carbon dioxide gas (CO _{2 )} generated from amidation. ) is the value obtained by subtracting the theoretical quantity.

From the viewpoint of increasing the alkali solubility of the polyamideimide resin, it is preferable that the portion represented by Y in the general formulas (1) and (2) has a cyclohexane ring. From the viewpoint of improving the balance of other properties such as the alkali solubility of the polyamideimide resin and the mechanical properties of the cured product of the resin composition containing the polyamideimide resin, the quantity of the aromatic ring and cyclohexane ring in the portion represented by Y above. The relationship is that the molar ratio of the content of the cyclohexane ring to the content of the aromatic ring is preferably 85/15 to 100/0, more preferably 90/10 to 99/1, and 90/10 to 98/2. It is more desirable.

The method for producing the above-mentioned (A) alkali-soluble polyamidoimide resin is not limited, and it can be produced through an imidization step and an amido-imide step using a known and common method.

In the imidization process, dimer diamine (a), carboxyl group-containing diamine (b), cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (c), and trimellitic anhydride (d) are used. An imidide is obtained by reacting one or two types selected from the group.

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

If necessary, other diamines may be used along with dimer diamine (a) and carboxyl group-containing diamine (b). Specific examples of other diamines 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)diphenyl sulfone, (4,4'-dia Mino)benzophenone, (3,3'-diamino)benzophenone, (4,4'-diamino)diphenylmethane, (4,4'-diamino)diphenyl ether, (3,3'-diamino) Aromatic diamines such as mino)diphenyl ether are included, and hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, octadecamethylenediamine, 4,4'-methylenebis(cyclohexylamine), Aliphatic diamines such as isophorone diamine, 1,4-cyclohexane diamine, and norbornene diamine can be mentioned.

From the viewpoint of increasing the alkali solubility of the polyamideimide 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) to the amount of trimellitic anhydride (d) is preferably 85/15 to 100/0. And, it is more preferable that it is 90/10 to 99/1, and even more preferably it is 90/10 to 98/2.

The amount of diamine compound (specifically, dimer diamine (a) and carboxyl group-containing diamine (b) and other diamines used as necessary) used to obtain the imidate and the acid anhydride (specifically, cyclo refers to one or two types selected from the group consisting of hexane-1,2,4-tricarboxylic acid-1,2-anhydride (c) and trimellitic anhydride (d).) The positive relationship is It is not limited. It is preferable that the molar ratio of the acid anhydride used is 2.0 or more and 2.4 or less with respect to the usage amount of the diamine compound, and it is more preferable that the molar ratio is 2.0 or more and 2.2 or less.

In the amido-imide process, a diisocyanate compound is reacted with the imidized product obtained through the above imide chemical process to obtain a polyamide-imide resin containing a substance having a structure represented by the general formula (3) described later.

The specific type of diisocyanate compound is not limited. The diisocyanate compound may be comprised of one type of compound, or may be comprised of multiple 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, Aromatic diisocyanates such as m-xylylene diisocyanate and 2,4-tolylene dimer; and aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and norbornene diisocyanate. (A) 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 desirable.

The amount of diisocyanate compound used in the amidimidization process is not limited. From the viewpoint of providing appropriate alkali solubility to the polyamide-imide resin, the amount of diisocyanate compound used is preferably 0.3 or more and 1.0 or less, and is preferably 0.4 or more as a molar ratio to the amount of the diamine compound used to obtain the imide compound. It is more preferable to set it to 0.95 or less, and it is especially preferable to set it to 0.50 or more and 0.90 or less.

The polyamideimide resin produced in this way has the following general formula (3)

(In the general formula (3), It includes substances having a structure represented by .

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

[(B) Photobase generator]

The curable resin composition of the first aspect of the present invention includes (A) an alkali-soluble polyamideimide resin (and (E) an alkali-soluble polyimide resin of an optional component described later), (C) a thermosetting compound, and (B) It is preferable to include a photobase generator, and the curable resin composition of the second aspect of the present invention includes (B) a photobase generator. (B) The photobase generator is capable of functioning as a catalyst for the addition reaction of a polyimide resin having a carboxyl group and a thermosetting component by changing the molecular structure or cleavage of the molecule by irradiation with light such as ultraviolet rays or visible light. It is a compound that produces one or more basic substances.

Examples of basic substances include 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, nitrobenzylcarbamate groups, and alkoxybenzyl carbohydrates. Compounds having a substituent such as a bamate group, etc. can be mentioned. Among them, oxime ester compounds and α-aminoacetophenone compounds are preferable. As the α-aminoacetophenone compound, those having two or more nitrogen atoms are particularly preferable.

As other photobase generators, WPBG-018 (brand name: 9-anthrylmethyl N,N'-diethylcarbamate), WPBG-027 (brand name: (E)-1-[3-(2-hydroxy Phenyl)-2-propenoyl] piperidine), WPBG-082 (Product name: Guanidinium 2-(3-benzoylphenyl)propionate), WPBG-140 (Product name: 1-(Anthraquinone-2- 1) Ethyl imidazole carboxylate) etc. (above, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) can also be used. The α-aminoacetophenone compound has a benzoin ether bond in the molecule, and when exposed to light, cleavage occurs within the molecule, and a basic substance (amine) that acts as a curing catalyst is generated.

Specific examples of α-aminoacetophenone compounds include (4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane (Omnirad 369, brand name, manufactured by IGM Resins) and 4-(methylthiobenzoyl). -1-Methyl-1-morpholinoethane (Omnirad 907, brand name, manufactured by IGM Resins), 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-( Commercially available compounds such as 4-morpholinyl)phenyl]-1-butanone (Omnirad 379, brand name, manufactured by IGM Resins) or solutions thereof can be used.

As the oxime ester compound, any compound can be used as long as it produces a basic substance when irradiated with light. As such an oxime ester compound, an oxime ester-based photobase generator having a group represented by the following general formula (4) is preferable.

(Wherein, R ₁ is a hydrogen atom, an unsubstituted or C1-C6 alkyl group, a phenyl group or a halogen atom-substituted phenyl group, an unsubstituted or C1-C20 alkyl group substituted by one or more hydroxyl groups, or one or more oxygen atoms. The corresponding alkyl group is interrupted, an unsubstituted or alkyl group with 1 to 6 carbon atoms or a cycloalkyl group with 5 to 8 carbon atoms substituted with a phenyl group, an alkanoyl group with 2 to 20 carbon atoms unsubstituted or substituted with an alkyl group with 1 to 6 carbon atoms or a phenyl group, or Represents a benzoyl group, and R ₂ is an unsubstituted or alkyl group having 1 to 6 carbon atoms, a phenyl group or a phenyl group substituted with a halogen atom, an alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with one or more hydroxyl groups, or the corresponding group interrupted by one or more oxygen atoms. Represents an alkyl group, an unsubstituted alkyl group with 1 to 6 carbon atoms or a cycloalkyl group with 5 to 8 carbon atoms substituted with a phenyl group, an alkanoyl group with 2 to 20 carbon atoms or a benzoyl group unsubstituted or substituted with an alkyl group with 1 to 6 carbon atoms or a phenyl group. .)

Commercially available oxime ester photobase generators include IRGACURE OXE01 and IRGACURE OXE02 manufactured by BASF Japan, N-1919 and NCI-831 manufactured by ADEKA. Additionally, compounds having two oxime ester groups in the molecule described in Japanese Patent No. 4344400 can also be suitably used.

In addition, Japanese Patent Laid-open No. 2004-359639, Japanese Patent Laid-Open No. 2005-097141, Japanese Patent Laid-Open No. 2005-220097, Japanese Patent Laid-Open No. 2006-160634, and Japanese Patent Laid-Open No. 2008-094770 and carbazole oxime ester compounds described in Japanese Patent Application Publication No. 2008-509967, Japanese Patent Application Publication No. 2009-040762, and Japanese Patent Application Publication No. 2011-80036.

These photobase generators may be used individually, or may be used in combination of two or more types. The compounding amount of the photobase generator (B) in the curable resin composition of the present invention is (A) relative to 100 parts by mass of the alkali-soluble polyamidoimide resin, or when an alkali-soluble polyimide resin is contained, (A) For example, it is 0.1 part by mass or more and 40 parts by mass or less, and preferably 0.2 part by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the total amount of the alkali-soluble polyamideimide resin and the alkali-soluble polyimide resin.

In the case of 0.1 mass part or more, good development resistance contrast of the light irradiated part/unirradiated part can be obtained. Additionally, in the case of 40 parts by mass or less, the properties of the cured product improve.

[(C) Thermosetting compound]

The curable resin composition of the first aspect of the present invention preferably contains (C) a thermosetting compound from the viewpoint of imparting heat resistance and chemical resistance to the cured product after heat curing, and the curable resin composition of the second aspect of the present invention (C) includes thermosetting compounds.

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

Especially, from the viewpoint of heat resistance and chemical resistance, it is preferable that the thermosetting compound (C) is 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 Nittetsu Chemical & Materials Corporation, D.E.R.317 manufactured by Dow Chemical Corporation, and Sumitomo Chemical Corporation. Bisphenol A type epoxy resins such as Sumiepoxy ESA-011 (all brand names); Bromination of jERYL903 manufactured by Mitsubishi Chemical Corporation, EPICLON152 manufactured by DIC Corporation, Epotot YDB-400 manufactured by Nittetsu Chemical & Materials Corporation, D.E.R.542 manufactured by Dow Chemical Corporation, and Sumiepoxy ESB-400 manufactured by Sumitomo Chemical Corporation (all brand names). epoxy resin; jER152 manufactured by Mitsubishi Chemical Corporation, D.E.N.431 manufactured by Dow Chemical Corporation, EPICLON N-730 manufactured by DIC Corporation, EPOTOT YDCN-701 manufactured by Nittetsu Chemical & Materials Corporation, EPPN-201 manufactured by Nippon Kayaku Corporation, manufactured by Sumitomo Chemical Corporation. Novolak-type epoxy resins such as Sumiepoxy ESCN-195X (all brand names); Bisphenol F-type epoxy resins such as EPICLON830 manufactured by DIC, jER807 manufactured by Mitsubishi Chemical Corporation, and EPOTOT YDF-170, YDF-175, and YDF-2004 manufactured by Nittetsu Chemical & Materials Corporation (all brand names); Hydrogenated bisphenol A type epoxy resins such as Epotot ST-2004 (brand name) manufactured by Nittetsu Chemical &Materials; glycidylamine-type epoxy resins such as jER604 manufactured by Mitsubishi Chemical Corporation, Epotot YH-434 manufactured by Nittetsu Chemical & Materials Corporation, and Sumiepoxy ELM-120 manufactured by Sumitomo Chemical Corporation (all brand names); Hidanto doll epoxy resin; Alicyclic epoxy resins such as Celoxide 2021 manufactured by Daicel (all brand names); Trihydroxyphenylmethane type epoxy resins such as EPPN-501 manufactured by Nippon Kayaku Co., Ltd. (all brand names); bixylenol-type or biphenol-type epoxy resins such as YL-6056, YX-4000, and YL-6121 (all brand names) manufactured by Mitsubishi Chemical Corporation, or mixtures thereof; bisphenol S-type epoxy resins such as EBPS-200 manufactured by Nippon Kayaku Corporation, EPX-30 manufactured by ADEKA Corporation, and EXA-1514 (brand name) manufactured by DIC Corporation; Bisphenol A novolak-type epoxy resins such as jER157S (brand name) manufactured by Mitsubishi Chemical Corporation; Heterocyclic epoxy resins such as TEPIC manufactured by Nissan Chemical Industries, Ltd. (all brand names); Biphenyl novolac type epoxy resin; Naphthalene group-containing epoxy resins such as ESN-190 manufactured by Nittetsu Chemical & Materials and HP-4032 manufactured by DIC; Epoxy resins having a dicyclopentadiene skeleton, such as HP-7200 manufactured by DIC, etc. can be mentioned.

(C) The thermosetting compound may be mixed in any amount, but (A) the alkali-soluble polyamideimide resin and, if included, the equivalent ratio (alkali-soluble group: thermosetting group such as epoxy group) of the alkali-soluble polyimide resin is 1:0.1. It is preferable to mix in a ratio of 1:10.

[(D) Cellulose derivative]

The curable resin composition of the first aspect of the present invention preferably contains (D) a cellulose derivative as a polymer component that has different compatibility from the thermosetting compound (C) or the alkali-soluble photocurable compound. The curable resin composition of the second aspect includes (D) a cellulose derivative. When the (D) cellulose derivative is included in the curable resin composition of the present invention, the (D) cellulose derivative is soluble in an organic solvent and a material having a high glass transition temperature (Tg) is preferred. (D) Cellulose derivatives include cellulose ether, carboxymethyl cellulose, cellulose ester, etc. as described later.

Examples of cellulose ethers include ethylcellulose and hydroxyalkylcellulose. Commercially available products of ethylcellulose include Ethocell (registered trademark) 4, Ethocell 7, Ethocell 10, Ethocell 14, Ethocell 20, and Ethocell 45. Ethocell 70, Ethocell 100, Ethocell 200, and Ethocell 300 (all brand names manufactured by Dow Chemical Co., Ltd.). Commercially available products of hydroxyalkyl cellulose include Metholose SM, Metholose 60SH, Metholose 65SH, and Metolo. Oz 90SH, Metholose SEB, Metholose SNB (all brand names manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

Additionally, commercially available carboxymethylcellulose products include CMCAB-641-0.2 (trade name manufactured by Eastman Chemical), Sunrose F, Sunrose A, Sunrose P, Sunrose S, and Sunrose B (all manufactured by Nippon Seishi Corporation). product name), etc.

A more preferable cellulose derivative is a cellulose ester obtained by esterifying the hydroxyl group of cellulose with an organic acid, and specifically, the following formula (5)

(In formula (5), R ₁ , R ₂ and R ₃ are each independently hydrogen, an acyl group, or formula (6)

(In formula (6), R ₄ is hydrogen or a methyl group, and R ₅ is hydrogen, a methyl group, an ethyl group, or a glycidyl group.), at least one of R ₁ , R ₂ and R ₃ is hydrogen, and n is It is an integer of 1 or more, and the upper limit is regulated from the molecular weight described later.) Examples include compounds represented by.

In the cellulose ester represented by the above formula (5), the content of acyl groups with respect to the cellulose resin is in the range of more than 0 and 60 wt% or less, and is preferably in the range of 5 to 55 wt%.

In the cellulose ester represented by the above formula (5), the hydroxyl group content relative to the cellulose resin is 0 to 6 wt%, the acetyl group content as an acyl group is 0 to 40 wt%, and the propionyl group or/and butyryl group content is The content of the group represented by formula (6) is preferably in the range of 0 to 20 wt%. “wt%” herein refers to the weight% of hydrogen, an acyl group, or a group represented by formula (6) relative to the weight of cellulose.

Commercially available products of such cellulose ester include CA-398-3, CA-398-6, CA-398-10, CA-398-30, CA-394-60S, etc. as cellulose acetate, and CAB-551 as cellulose acetate butyrate. -0.01, CAB-551-0.2, CAB-553-0.4, CAB-531-1, CAB-500-5, CAB-381-0.1, CAB-381-0.5, CAB-381-2, CAB-381-20 , CAB-381-20BP, CAB-321-0.1, CAB-171-15, etc., as cellulose acetate propionate, CAP-504-0.2, CAP-482-0.5, CAP-482-20 (all of the above cellulose derivatives are (trade name manufactured by Eastman Chemical), etc. can be mentioned. Among these, cellulose acetate butyrate and cellulose acetate propionate are preferable from the viewpoint of solubility in solvents.

In addition, the cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are mixed with (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, glycidyl (meth)acrylate, etc. in the presence of an oxidizing agent such as benzoyl peroxide. By reacting, a cellulose derivative containing the group represented by formula (6) can be obtained. By using a cellulose derivative containing the group represented by this formula (6), the evaluation results of adhesion become better.

(D) The number average molecular weight of the cellulose derivative is not particularly limited, but is preferably 5,000 to 500,000, more preferably 10,000 to 100,000, and still more preferably 10,000 to 30,000. When the molecular weight is within the above range, the sticking effect is small, that is, the evaluation result of the sticking property becomes good, and the viscosity of the curable resin composition becomes an appropriate range.

In addition, the glass transition temperature Tg referred to in this specification refers to the glass transition temperature measured by thermomechanical analysis (DSC) according to the method described in “5.17.5DSC method” of JIS C 6481: 1996.

The cellulose derivative used in the present invention is preferably derived from natural products from the viewpoint of depleting fossil fuels. In addition, the starting raw material used for the cellulose derivative of the present invention can be manufactured from recycled products such as recycled pulp, and a composition that is preferable from the environmental perspective of CO ₂ reduction can be provided.

(D) Cellulose derivatives can be used individually or in a mixture of two or more types. (D) The mixing amount of the cellulose derivative is, for example, 0.5 parts by mass or more and 20 parts by mass or less, with respect to 100 parts by mass of (A) alkali-soluble polyamideimide resin (and alkali-soluble polyimide resin of optional components described later). , Preferably it is 1 mass part or more and 15 mass parts or less, More preferably, it is 4 mass parts or more and 10 mass parts or less. In the case of the above range, at the time of the dry coating film, the surface roughness (arithmetic average roughness Ra) can be less than 0.1 ㎛, the sticking area is small, that is, the evaluation results of sticking properties are good, and the viscosity of the curable resin composition is in an appropriate range. do.

This is believed to be because the compatibility of (A) the alkali-soluble polyamidoimide resin, (C) the thermosetting compound, and (D) the cellulose derivative is good before heat curing, and the polymer component exists dispersed in the dried coating film.

In addition, after thermal curing, the polymer component dispersed in the dry coating film migrates to the film surface during the thermal curing reaction, so that the surface roughness (arithmetic mean roughness Ra) of the cured film after thermal curing is higher than that of the dry coating film before thermal curing. It is thought that it becomes larger, and by setting the number average molecular weight and mixing amount of the cellulose derivative (D) within the above-mentioned range, the surface roughness (arithmetic average roughness Ra) after curing can also be set to 0.1 μm or more and 1 μm or less.

[(E) Alkali-soluble polyimide resin]

From the viewpoint of heat resistance, the curable resin composition of the present invention preferably contains (E) an alkali-soluble polyimide resin.

(E) The alkali-soluble polyimide resin 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 development of the curable resin composition of the present invention in an alkaline solution, and examples include a carboxyl group and a phenolic hydroxyl group.

Examples of such (E) alkali-soluble polyimide resin include resins 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. Additionally, imidization may be performed by thermal imidation, chemical imidation, or a combination of these.

Examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydride and tricarboxylic acid anhydride, but are not limited to these acid anhydrides. Any compound having an acid anhydride group and a carboxyl group that reacts with an amino group or an isocyanate group may be used. It can be used including derivatives. Additionally, these carboxylic acid anhydride components may be used individually or in combination.

As the amine component, diamines such as aliphatic diamine and aromatic diamine, polyhydric amines such as aliphatic polyetheramine, diamines having a carboxyl group, diamines having a phenolic hydroxyl group, etc. 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 type of functional group of a phenolic hydroxyl group or a carboxyl group. Additionally, these amine components may be used individually or in combination.

As the isocyanate component, diisocyanates such as aromatic diisocyanates and their isomers and multimers, aliphatic diisocyanates, alicyclic diisocyanates and their isomers, and other general-purpose diisocyanates can be used, but are not limited to these isocyanates. . In addition, these isocyanate components may be used individually or in combination.

In the synthesis of such (E) alkali-soluble polyimide resin, known and commonly used organic solvents can be used. There is no problem as such an organic solvent as long as it is a solvent that does not react with the raw materials such as carboxylic acid anhydrides, amines, and isocyanates and dissolves these raw materials, and its structure is not particularly limited. In particular, because of the high solubility of the raw materials, aprotic substances such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and γ-butyrolactone. Solvent is preferred.

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

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

In addition, considering the developability and cured film properties, the molecular weight of the alkali-soluble polyimide resin is preferably 100,000 or less, more preferably 1,000 to 100,000, and still more preferably 2,000 to 50,000.

(E) When an alkali-soluble polyimide resin is mixed, from the viewpoint of improving heat resistance and developability, the mixing ratio of (A) alkali-soluble polyamidoimide resin and (E) alkali-soluble polyimide resin is mass ratio. It can be 98:2 to 50:50, preferably 95:5 to 50:50, and more preferably 95:5 to 70:30.

The following components can be further added to the curable resin composition of the present invention as needed.

[Polymer resin]

The curable resin composition of the present invention can be blended with known and commonly used polymer resins for the purpose of improving the flexibility and drying-to-touch properties of the resulting cured product. Examples of such polymer resins include polyester-based polymers, phenoxy resin-based polymers, polyvinyl acetal-based polymers, polyvinyl butyral-based polymers, polyamide-based polymers, and elastomers. These polymer resins may be used individually or in combination of two or more types.

[Inorganic filler]

The curable resin composition of the present invention may contain an inorganic filler to suppress curing shrinkage of the cured product and improve properties such as adhesion and hardness. Such inorganic fillers include, for example, barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, Neuburg Silicious Earth. etc. can be mentioned.

[coloring agent]

The curable resin composition of the present invention can contain commonly known colorants such as red, orange, blue, green, yellow, white, and black. These colorants may be any of pigments, dyes, and pigments.

[Organic solvent]

The curable resin composition of the present invention can be blended with an organic solvent to prepare the resin composition or to adjust 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. These organic solvents may be used individually or as a mixture of two or more types.

[Other ingredients]

The curable resin composition of the present invention may further contain components such as a mercapto compound, an adhesion promoter, an antioxidant, and an ultraviolet absorber, as needed. These can be used as known and common ones.

In addition, well-known thickeners such as fine powdered silica, hydrotalcite, organic bentonite, and montmorillonite, and well-known additives such as silicone-based, fluorine-based, polymer-based antifoaming agents and/or leveling agents, silane coupling agents, and rust inhibitors can be mixed. You can.

<Layered structure>

In the laminated structure of the present invention, at least one side of the resin layer formed from the curable resin composition of the present invention 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 from the curable resin composition of the present invention may be laminated, or a resin layer formed from the curable resin composition of the present invention and a curable resin composition other than the present invention may be used. A laminated structure of formed resin layers may be used.

When taking the latter laminated structure, the laminated structure has a laminated structure of, for example, a resin layer (A) provided on a substrate such as a flexible printed wiring board, and a resin layer (B) provided on the resin layer (A). At least one side of the resin layer is supported or protected by a film. The resin layer (A) contains, 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, 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 viscosity on a carrier film (support film), and then applied by a known method such as a comma coater according to a conventional method. . When the resin layer has a laminated structure, the application operation is repeated with or without changing the resin composition to be applied. Thereafter, the laminate structure of the present invention is formed by forming a dry coating film of a resin layer in a B stage state (semi-cured state) on a carrier film by drying at a temperature of usually 50 to 130° C. for 1 to 30 minutes. . The resin layer of this laminated structure is a so-called dry film. On this dry film, a cover film (protective film) that can be further peeled can be laminated for the purpose of preventing dust from adhering to the surface of the dried coating film. As the carrier film and the cover film, conventionally known plastic films can be appropriately used, and the cover film is preferably smaller than the adhesive force between the resin layer and the carrier film when peeling off the cover film. There is no particular limitation on the thickness of the carrier film and cover film, but is generally appropriately selected in the range of 10 to 150 μm.

<Hardened 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 of the present invention.

<Electronic components>

The curable resin composition of the present invention and the resin layer of the laminated structure of the present invention can be effectively used in electronic components such as flexible printed wiring boards, for example. Specifically, a flexible print having a cured product of an insulating film formed by forming a layer of the curable resin composition of the present invention or a resin layer of a laminated structure on a flexible printed wiring substrate, patterning it by light irradiation, and forming a pattern with a developer. A wiring board, etc. may be mentioned.

Hereinafter, the manufacturing method of the flexible printed wiring board will be described in detail.

<Manufacturing method of 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 of the present invention is shown below. That is, a process of applying the curable resin composition of the present invention on a flexible printed wiring substrate on which a conductor circuit is formed, or attaching the resin layer of the laminated structure of the present invention to form a resin layer (layer forming process), this resin layer It is a manufacturing method including a step of irradiating active energy rays in a pattern (exposure step), and a step of alkali developing the resin layer after exposure to form a patterned resin layer (development step). In addition, if necessary, after alkali development, further photocuring or thermal curing (post-curing process) is performed to completely cure the resin layer, form a cured film, and obtain a highly reliable flexible printed wiring board.

In addition, the manufacture of a flexible printed wiring board using the curable resin composition of the present invention or the resin layer of the laminated structure of the present invention can also be performed according to other procedures. That is, a process of applying the curable resin composition of the present invention on a flexible printed wiring substrate on which a conductor circuit is formed, or attaching the resin layer of the laminated structure of the present invention to form a resin layer (layer forming process), this resin layer A process of irradiating active energy rays in a pattern (exposure process), a process of heating the exposed resin layer (heating (PEB) process), and alkali development of the heated resin layer to form a patterned resin layer. It is a manufacturing method that includes a process (development process). In addition, if necessary, after alkali development, further photocuring or thermal curing (post-curing process) is performed to completely cure the resin layer, form a cured film, and obtain a highly reliable flexible printed wiring board.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples. In addition, unless specifically mentioned below, "part" shall mean the mass part of solid content.

((A) Synthesis of alkali-soluble polyamideimide resin)

[Synthesis Example 1]

In a four-necked 300 mL flask equipped with a nitrogen gas introduction tube, thermometer, and stirrer, 28.61 g (0.052 mol) of aliphatic diamine derived from dimer acid with 36 carbon atoms as dimer diamine (a) (manufactured by Croda Japan, product name PRIAMINE1075), and a carboxyl group. 4.26 g (0.028 mol) of 3,5-diaminobenzoic acid and 85.8 g of γ-butyrolactone as contained diamine (b) were added 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 kept at room temperature for 30 minutes. Additionally, 30 g of toluene was added, the temperature was raised to 160°C, the water generated along with the toluene was removed, maintained for 3 hours, and cooled to room temperature to obtain a solution containing the imidide.

14.30 g (0.068 mol) of trimethylhexamethylene diisocyanate as a diisocyanate compound was added to the solution containing the obtained imidate, maintained at a temperature of 160°C for 32 hours, and diluted with 21.4 g of cyclohexanone (A). A solution (A-1) containing an alkali-soluble polyamideimide resin was obtained. The mass average molecular weight Mw of the obtained polyamidoimide resin was 5250, the solid content was 41.5 mass%, the acid value was 63 mgKOH/g, and the content of dimer diamine (a) was 40.0 mass%.

[Synthesis Example 2]

In a four-necked 300 mL flask equipped with a nitrogen gas introduction tube, thermometer, and stirrer, 29.49 g (0.054 mol) of aliphatic diamine derived from dimer acid with 36 carbon atoms as dimer diamine (a) (manufactured by Croda Japan, product name PRIAMINE1075), carboxyl group. 4.02 g (0.026 mol) of 3,5-diaminobenzoic acid and 73.5 g of γ-butyrolactone as contained diamine (b) were added and dissolved at room temperature.

Next, 31.71 g (0.160 mol) of cyclohexane-1,2,4-tricarboxylic anhydride (c) and 1.54 g (0.008 mol) of trimellitic anhydride (d) were added, and kept at room temperature for 30 minutes. Additionally, 30 g of toluene was added, the temperature was raised to 160°C, the water generated along with the toluene was removed, maintained for 3 hours, and cooled to room temperature to obtain a solution containing the imidide.

6.90 g (0.033 mol) of trimethylhexamethylene diisocyanate and 8.61 g (0.033 mol) of dicyclohexylmethane diisocyanate as diisocyanate compounds were added to the solution containing the obtained imidized product, and incubated at a temperature of 160°C for 32 hours. By holding and diluting with 36.8 g of cyclohexanone (A), a solution (A-2) containing an alkali-soluble polyamidoimide resin was obtained. The mass average molecular weight Mw of the obtained polyamidoimide resin was 5840, the solid content was 40.4 mass%, the acid value was 62 mgKOH/g, and the content of dimer diamine (a) was 40.1 mass%.

[Synthesis Example 3]

6.98 g of 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 3.80 g of 3,5-diaminobenzoic acid, and polyether were added to a 4-necked 300 mL flask equipped with a nitrogen gas introduction tube, thermometer, and stirrer. 8.21 g of diamine (manufactured by Huntsman, product name Elastamine RT1000, molecular weight 1025.64) and 86.49 g of γ-butyrolactone were added 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 added, and kept at room temperature for 30 minutes. Additionally, 30 g of toluene was added, the temperature was raised to 160°C, the water generated along with the toluene was removed, maintained for 3 hours, and cooled to room temperature to obtain an imidide solution.

To the obtained imidate solution, 9.61 g of trimellitic anhydride and 17.45 g of trimethylhexamethylene diisocyanate were added, and the temperature was maintained at 160°C for 32 hours. In this way, (A) alkali-soluble polyamideimide resin solution (A-3) containing a carboxyl group was obtained. The solid content was 40.1 mass% and the acid value was 83 mgKOH/g.

((E) Synthesis of alkali-soluble polyimide resin)

[Synthesis Example 4]

In a separable three-necked flask equipped with a stirrer, nitrogen introduction tube, dividing ring, and cooling ring, 22.4 g of 3,3'-diamino-4,4'-dihydroxydiphenylsulfone, 2,2'-bis[ Add 8.2g of 4-(4-aminophenoxy)phenyl]propane, 30g of NMP, 30g of γ-butyrolactone, 27.9g of 4,4'-oxydiphthalic anhydride, and 3.8g of trimellitic anhydride. , and stirred for 4 hours at room temperature and 100 rpm under a nitrogen atmosphere. 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 distilling off toluene and water 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 equivalent was 390.

((D) Synthesis of cellulose derivatives)

[Synthesis Example 5]

64 g of methyl ethyl ketone and 16 g of CAB-553-0.4 (cellulose acetate derivative, manufactured by Eastman Chemical Company) were added to a flask equipped with a stirrer, thermometer, and reflux condenser, and stirred at 75°C for 1 hour. Next, a mixture obtained by pre-mixing 15 g of methyl methacrylate and 1 g of benzoyl peroxide was added dropwise over 3 hours. After the dropwise addition was completed, the mixture obtained by pre-mixing 0.5g of benzoyl peroxide and 5g of methyl ethyl ketone was added dropwise over 1 hour while maintaining the temperature at 75°C. Additionally, stirring was 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). In addition, the heating residue of resin solution CA-1 was 20.0 mass%.

[Synthesis Example 6]

64 g of methyl ethyl ketone and 16 g of CAB-553-0.4 (cellulose acetate derivative, manufactured by Eastman Chemical Company) were added to a flask equipped with a stirrer, thermometer, and reflux condenser, and stirred at 75°C for 1 hour. Next, a mixture obtained by pre-mixing 15 g of glycidyl methacrylate and 1 g of benzoyl peroxide was added dropwise over 3 hours. After the dropwise addition was completed, the mixture obtained by pre-mixing 0.5g of benzoyl peroxide and 5g of methyl ethyl ketone was added dropwise over 1 hour while maintaining the temperature at 75°C. Additionally, stirring was 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). In addition, the heating residue of resin solution CA-2 was 20.0 mass%.

[Examples of curable resin compositions of the first aspect of the present invention]

<1-1. Preparation of curable resin compositions of Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-3>

According to the component composition shown in Table 1 below, the materials of the curable resin compositions of Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-3 were mixed, premixed with a stirrer, and then mixed with three By kneading with a roll mill, each curable resin composition for forming a resin layer was adjusted. In addition, the values in Table 1 are parts by mass of solid content, unless otherwise specified.

For each of the curable resin compositions above, as described below, a resin layer (dry coating film) in the B stage state (semi-cured state) of each curable resin composition was formed and the resolution was evaluated. In addition, as described later, regarding the flexible wiring board having a resin layer in the B stage state (semi-cured state) and the flexible wiring board having the cured product of the resin layer, the B stage state (semi-cured state)/thermal curing The surface roughness of each subsequent coating film was evaluated. In addition, the flexible wiring board having the cured resin layer was evaluated for heat resistance (solder heat resistance), gold plating resistance (chemical resistance), flexibility, and stickability. The results are shown in Table 1.

<1-2. Formation of resin layer>

A flexible printed wiring substrate on which a circuit with a copper thickness of 18 µm was formed was prepared, and pretreatment was performed using Mack CZ-8100. Thereafter, the film thickness after drying each curable resin composition obtained in Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-3 on the pretreated flexible printed wiring substrate was the film thickness shown in Table 1. It was applied so that After that, it was dried at 90°C for 30 minutes in a hot air circulation type drying furnace to form a resin layer (dry coating film) in a B stage state (semi-cured state).

<1-3. Fabrication of evaluation board>

For the uncured resin layer on each flexible printed wiring substrate on which the resin layer was formed as described above, an exposure device equipped with a metal halide lamp (HMW-680-GW20: manufactured by Oak Seisakusho) was used, and a negative mask was applied. The pattern was exposed to 300mJ/cm ² to form an opening with a diameter of 200㎛. After that, a PEB process was performed at 90°C for 30 minutes, development (30°C, 0.2 MPa, 1% by mass Na ₂ CO ₃ aqueous solution) was performed for 60 seconds, and heat curing was performed at 150°C for 60 minutes to form a cured resin layer ( A flexible printed wiring board (evaluation board) on which a cured coating film was formed was produced.

<1-4. Evaluation of surface roughness>

<1-2. A resin layer (dry coating film) in a B stage state (semi-cured state) formed on a flexible printed wiring substrate as described in <Formation of Resin Layer>, or <1-3. The arithmetic mean surface roughness Ra was measured for the resin layer on the evaluation substrate after heat curing, which was produced as described in <Production of evaluation substrate>. The measured value was the average value of five arbitrary points in an observation range of 100 × 100 μm. A shape measurement laser microscope (VK-X100, manufactured by Keyence Corporation) was used to measure the arithmetic mean surface roughness Ra. After starting the shape measurement laser microscope (VK- (with the noodles at the top) was placed on top. By turning the lens revolver of the microscope unit (VK-X110, manufactured by Keyence Corporation), an objective lens with a magnification of 10x was selected, and the focus and brightness were roughly adjusted in the image observation mode of the VK observation application (VK-H1VX). . The x-y stage was manipulated so that the part of the sample surface to be measured was at the center of the screen. The objective lens with a magnification of 10x was changed to a magnification of 100x, and the surface of the sample was focused using the autofocus function of the image observation mode of the VK observation application (VK-H1VX). The simple mode of the shape measurement tab of the VK observation application (VK-H1VX) was selected, the measurement start button was pressed, the surface shape of the sample was measured, and a surface image file was obtained. The VK analysis application (VK-H1XA, manufactured by Keyence Corporation) was started, the obtained surface image file was displayed, and then tilt correction was performed.

In addition, the observation measurement range (horizontal) in measuring the surface shape of the sample was set to 100 μm × 100 μm. Display the line illuminance window, select JIS B 0601-1994 in the parameter setting area, select a horizontal line from the measurement line button, display a horizontal line anywhere in the surface image, and press the OK button to obtain the arithmetic mean. The numerical value of surface roughness Ra was obtained. Additionally, horizontal lines were displayed at four other locations in the surface image, and the numerical value of each arithmetic mean surface roughness Ra was obtained. The average value of the five obtained values was calculated and used as the arithmetic average surface roughness Ra value of the surface of each resin layer.

<1-5. Evaluation of resolution>

<1-2. For the resin layer (dry coating film) in the B stage state (semi-cured state) formed on the flexible printed wiring substrate as described in <Formation of Resin Layer>, <1-4. As described in <Evaluation of Surface Roughness>, the arithmetic mean roughness Ra of each dry coating film was measured, and the dry coating films of each Example, Comparative Example 1-1, and Comparative Example 1-3 were less than 0.1 μm. The arithmetic mean roughness Ra of the dried coating film of Comparative Example 1-2 was 0.1 or more. For each of these dried coating films, first, using an exposure device equipped with a metal halide lamp (HMW-680-GW20: manufactured by Oak Seisakusho), openings with a diameter of 150 ㎛ and 200 ㎛ were formed at 300 mJ/cm ² through a negative mask. The pattern was exposed to do so. The substrate having the resin layer after exposure was subjected to heat treatment at 90°C for 30 minutes.

Thereafter, the substrate was immersed in a 1% by mass aqueous sodium carbonate solution at 30°C, developed for 1 minute, the state of pattern formation was observed, and resolution was evaluated. The evaluation criteria are as follows.

◎: Aperture pattern of 150 ㎛ is well formed.

○: The 200 ㎛ opening pattern is well formed, but the 150 ㎛ opening pattern is slightly defective.

×: The unexposed portion shows developability, but formation of an aperture pattern of 200 μm is defective (resolution is insufficient).

<1-6. Evaluation of heat resistance (solder heat resistance)>

<1-3. Rosin-based flux was applied to the evaluation board manufactured as described in <Production of Evaluation Board>, dipped in a soldering bath previously set to 260°C for 20 seconds (10 seconds x 2 times), and expansion and peeling of the cured film were observed. By observation, 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 x 2 times.

○: There was no swelling or peeling even when immersed for 10 seconds x 1 time, but peeling occurred on the second immersion.

×: When immersed for 10 seconds × 1 time, swelling and peeling occurred.

<1-7. Evaluation of gold plating resistance (chemical resistance)>

<1-3. The evaluation was performed using the evaluation board manufactured as described in <Production of Evaluation Board> using the following method.

For the evaluation substrate, plating of 5 μm of nickel and 0.05 μm of gold was performed at 80 to 90°C using a commercially available electroless nickel plating bath and an electroless gold plating bath, and the substrate and cured film were observed to determine gold plating resistance. (Chemical resistance) was evaluated. The evaluation criteria are as follows.

○: No seepage between the substrate and the cured coating film.

△: Permeation between the substrate and the cured coating film is confirmed.

×: Peeling occurred in a part of the cured coating film.

<1-8. Flexibility (MIT test)>

<1-3. Each evaluation board manufactured as described in <Production of Evaluation Board> was used as a test piece, and the MIT test was performed using an MIT folding fatigue tester type D (manufactured by Toyo Seiki Seisakusho), treating the film as paper in accordance with JIS P8115. was performed and the flexibility was evaluated. Specifically, as shown in FIG. 1, the test piece 1 is mounted on the device and a load F (0.5 kgf) is applied, the test piece 1 is installed vertically on the clamp 2, and the bending angle is Bending was performed at α of 135 degrees and speed of 175 cpm, and the number of reciprocating bends until fracture was measured. Additionally, the test environment was 25°C and the radius of curvature was set to R=0.38mm. The evaluation criteria are as follows.

◎: It was bent more than 200 times, and no cracks occurred in the cured coating film at the bending point.

○: It was bent 170 to 199 times, and similarly no cracks occurred.

△: It was bent 150 to 169 times, and similarly no cracks occurred.

×: Cracks occurred when the number of bending was 149 or less.

<1-9. Adhesion>

<1-2. For the resin layer in the B stage state (semi-cured state) on each flexible printed wiring substrate, where the resin layer was formed as described in <Formation of Resin Layer>, <1-4. As described in <Evaluation of Surface Roughness>, the arithmetic mean roughness Ra of each dry coating film was measured, and the dry coating films of each Example, Comparative Example 1-1, and Comparative Example 1-3 were less than 0.1 μm. The arithmetic mean roughness Ra of the dried coating film of Comparative Example 1-2 was 0.1 or more. For each of these dried coating films, solid exposure was first performed at 300 mJ/cm ² through a negative mask using an exposure device equipped with a metal halide lamp (HMW-680-GW20: manufactured by Oak Seisakusho). Afterwards, a PEB process was performed at 90°C for 30 minutes, development (30°C, 0.2 MPa, 1 mass% Na ₂ CO ₃ aqueous solution) was performed for 60 seconds, and heat curing was performed at 150°C for 60 minutes to form a cured coating film. A flexible printed wiring board (evaluation board) was produced. For each cured film, <1-4. As described in <Evaluation of Surface Roughness>, the arithmetic mean roughness Ra of each dry coating film was measured, and the dry coating films of each Example, Comparative Example 1-2, and Comparative Example 1-3 were 0.1 μm or more and 1 μm or less. The arithmetic mean roughness Ra of the dried coating film of Comparative Example 1-1 was less than 0.1.

The obtained evaluation board was cut into a square with a side of 2 cm, 10 sheets were overlapped, and left for 72 hours at each temperature of 20, 30, 40, and 60°C, and then the presence or absence of sticking was confirmed. The evaluation criteria are as follows.

◎: No sticking at 60°C

○: There is no sticking at 40°C or lower, but there is some sticking at 60°C.

△: There is no sticking at 30℃ or lower, but there is sticking at 40℃ or higher.

×: Sticking is visible at any temperature

Details of the components in Table 1 are as follows.

A-1: Polyamideimide resin-containing solution prepared by [Synthesis Example 1] of the above-mentioned ((A) Synthesis of alkali-soluble polyamideimide resin)

A-2: Polyamideimide resin-containing solution prepared by [Synthesis Example 2] of the above-mentioned ((A) Synthesis of alkali-soluble polyamideimide resin)

A-3: Polyamideimide resin-containing solution prepared by [Synthesis Example 3] of the above-mentioned ((A) Synthesis of alkali-soluble polyamideimide resin)

PI-1: Alkali-soluble polyimide resin solution prepared by [Synthesis Example 4] of ((E) Synthesis of alkali-soluble polyimide resin) described above.

P7-532: Polyurethane acrylate, acid value 47mgKOH/g (manufactured by Kyoesha Chemical Co., Ltd.)

IRGACURE OXE02: Oxime-based photopolymerization initiator (manufactured by BASF)

CAB-553-0.4: Cellulose acetate derivative, number average molecular weight 20,000, 20 wt% DPM solution (manufactured by Eastman Chemical) (the parts in Table 1 represent the mass parts of the solid content of the 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) (the parts in Table 1 represent the mass parts of the solid content of the 20 wt% DPM solution)

JER828: Bisphenol A type epoxy resin, epoxy equivalent weight 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)

B-30: Barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.)

As shown in Table 1, from the comparison of examples and comparative examples, when a dry coating film with a thickness of 2 to 100 ㎛ is formed from a curable resin composition that is capable of alkali development and forms a cured film by exposure and heat treatment, this drying When the arithmetic mean roughness Ra of the coating film is less than 0.1 ㎛ and the arithmetic mean roughness Ra of the cured film after heat curing of the dry coating film is 0.1 ㎛ or more and 1 ㎛ or less, the formed resin layer (dry coating film) has low resolution. It was confirmed that the cured coating film (cured product) after heat curing was not only excellent in heat resistance, gold plating resistance, and flexibility, but also had small adhesion after high temperature storage.

In addition, from the comparison of Examples 1-1, 1-2, 1-4, 1-9 to 1-11 and Examples 1-3, 1-5 to 1-8, and 1-12, the film thickness of the dried coating film is 3 ㎛ or more and 80 ㎛ or less, the arithmetic average roughness Ra of the dry coating film is less than 0.05 ㎛, and the ratio of the arithmetic average roughness Ra of the cured film after heat curing to the arithmetic mean roughness Ra of the dry coating film (cured film after heat curing When the arithmetic average roughness Ra/arithmetic average roughness Ra of the dry coating film is set to 6 or more, the resolution of the formed resin layer (dry coating film) is greatly improved, and the cured coating film (cured product) after heat curing can be attached after high temperature storage. I noticed that it was getting smaller.

[Examples of curable resin compositions of the second aspect of the present invention]

<2-1. Preparation of curable resin compositions of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2>

According to the component composition shown in Table 2 below, the materials of the curable resin compositions of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2 were mixed, premixed with a stirrer, and then mixed with three By kneading with a roll mill, each curable resin composition for forming a resin layer was adjusted. In addition, the values in Table 2 are parts by mass of solid content, unless otherwise specified.

For each of the curable resin compositions above, as described below, a resin layer (dry coating film) in the B stage state (semi-cured state) of each curable resin composition was formed and the developability (alkali solubility) was evaluated. Additionally, 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 stickability were evaluated. The results are shown in Table 2.

<2-2. Formation of resin layer>

A flexible printed wiring substrate on which a circuit with a copper thickness of 18 µm was formed was prepared, and pretreatment was performed using Mack CZ-8100. Thereafter, each of the curable resin compositions obtained in Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-2 was applied to the pretreated flexible printed wiring substrate so that the film thickness after drying was 30 μm. . After that, it was dried at 90°C for 30 minutes in a hot air circulation type drying furnace to form a resin layer (dry coating film) in a B stage state (semi-cured state).

<2-3. Fabrication of evaluation board>

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

<2-4. Evaluation of developability (alkali solubility)>

<2-2. As described in <Formation of Resin Layer>, the resin layer (dry film) in the B stage state (semi-cured state) formed on the flexible printed wiring substrate was first exposed to an exposure device equipped with a metal halide lamp (HMW-680-GW20: Oak). (manufactured by Seisakusho), the pattern was exposed to light at 300 mJ/cm ² through a negative mask to form an opening with a diameter of 200 μm. The substrate having the resin layer after exposure was subjected to heat treatment at 90°C for 30 minutes.

Thereafter, the substrate was immersed in a 1% by mass aqueous sodium carbonate solution at 30°C, development was performed for 1 minute, the state of pattern formation was observed, and developability (alkali solubility) was evaluated. The evaluation criteria are as follows.

○: The exposed part shows development resistance, the unexposed part shows developability, and pattern formation is good.

×: Unexposed portion shows developability, but resolution pattern formation is poor (resolution is insufficient).

<2-5. Evaluation of heat resistance (solder heat resistance)>

<2-3. Rosin-based flux was applied to the evaluation board manufactured as described in <Production of Evaluation Board>, dipped in a soldering bath previously set to 260°C for 20 seconds (10 seconds x 2 times), and expansion and peeling of the cured film were observed. By observation, 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 x 2 times.

○: There was no swelling or peeling even when immersed for 10 seconds x 1 time, but peeling occurred on the second immersion.

×: When immersed for 10 seconds × 1 time, swelling and peeling occurred.

<2-6. Evaluation of gold plating resistance (chemical resistance)>

<2-3. The evaluation was performed using the evaluation board manufactured as described in <Production of Evaluation Board> using the following method.

For the evaluation substrate, plating of 5 μm of nickel and 0.05 μm of gold was performed at 80 to 90°C using a commercially available electroless nickel plating bath and an electroless gold plating bath, and the substrate and the cured film were observed for gold plating. Resistance (chemical resistance) was evaluated. The evaluation criteria are as follows.

○: No seepage between the substrate and the cured coating film.

△: Permeation between the substrate and the cured coating film is confirmed.

×: Peeling occurred in a part of the cured coating film.

<2-7. Flexibility (MIT test)>

<2-3. Each evaluation board manufactured as described in <Production of evaluation board> was used as a test piece, and an MIT fold fatigue tester type D (manufactured by Toyo Seiki Seisakusho) was used to perform the MIT test, treating the film as paper in accordance with JIS P8115. was performed and the flexibility was evaluated. Specifically, as shown in FIG. 1, the test piece 1 is mounted on the device and a load F (0.5 kgf) is applied, the test piece 1 is installed vertically on the clamp 2, and the bending angle is Bending was performed at α of 135 degrees and speed of 175 cpm, and the number of reciprocating bends until fracture was measured. Additionally, the test environment was 25°C and the radius of curvature was set to R=0.38mm. The evaluation criteria are as follows.

◎: It was bent more than 200 times, and no cracks occurred in the cured coating film at the bending point.

○: It was bent 170 to 199 times, and similarly no cracks occurred.

△: It was bent 150 to 169 times, and similarly no cracks occurred.

×: Cracks occurred when the number of bending was 149 or less.

<2-8. Adhesion>

<2-2. The resin layer (dry coating film) in the B stage state (semi-cured state) on each flexible printed wiring substrate on which the resin layer was formed as described in <Formation of Resin Layer> was first exposed to an exposure device (HMW-) equipped with a metal halide lamp. 680-GW20: manufactured by Oak Seisakusho), and 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, development (30°C, 0.2 MPa, 1% by mass Na ₂ CO ₃ aqueous solution) was performed for 60 seconds, and heat curing was performed at 150°C for 60 minutes to form a cured resin layer ( A flexible printed wiring board (evaluation board) on which a cured coating film was formed was produced.

The obtained evaluation board was cut into a square with a side of 2 cm, 10 sheets were overlapped, and left for 72 hours at each temperature of 20, 30, 40, and 60°C, and then the presence or absence of sticking was confirmed. The evaluation criteria are as follows.

◎: No sticking at 60°C

○: There is no sticking at 40°C or lower, but there is some sticking at 60°C.

△: There is no sticking at 30℃ or lower, but there is sticking when it is 40℃ or higher.

×: Sticking is visible at any temperature

Details of the components in Table 2-1 are as follows.

PI-1: Alkali-soluble polyimide resin solution prepared by [Synthesis Example 4] of ((E) Synthesis of alkali-soluble polyimide resin) described above.

A-3: Polyamideimide resin-containing solution prepared by [Synthesis Example 3] of the above-mentioned ((A) Synthesis of alkali-soluble polyamideimide resin)

A-1: Polyamideimide resin-containing solution prepared by [Synthesis Example 1] of the above-mentioned ((A) Synthesis of alkali-soluble polyamideimide resin)

P7-532: Polyurethane acrylate, acid value 47mgKOH/g (manufactured by Kyoesha Chemical Co., Ltd.)

IRGACURE OXE02: Oxime-based 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) (the parts in Table 2 represent the mass parts of the solid content of the 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) (the parts in Table 2 represent the mass parts of the solid content of the 20 wt% DPM solution)

CA-1: CAB-553-0.4 modified with methyl methacrylate, prepared by [Synthesis Example 5] ((D) Synthesis of cellulose derivatives), number average molecular weight 24,000, 20 wt% MEK solution (Table 2) (Parts represent mass parts of solid content of 20 wt% MEK solution)

CA-2: CAB-553-0.4 modified with glycidyl methacrylate, prepared by [Synthesis Example 6] ((D) Synthesis of cellulose derivatives), number average molecular weight 25,000, 20 wt% MEK solution (Table The number of parts in 2 represents the mass part of the solid content of the 20 wt% MEK solution)

jER828: Bisphenol A type epoxy resin, epoxy equivalent weight 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)

As shown in Table 2, from the comparison of examples and comparative examples, the curable resin composition contains (A) an alkali-soluble polyamideimide resin, (C) a thermosetting compound, and (B) a photobase generator, in addition to (D) a cellulose derivative. It was confirmed that by including, the developability of the formed resin layer was good, and the resin layer after curing was not only excellent in heat resistance, gold plating resistance, and flexibility, but also had small adhesion.

Additionally, from the comparison between Examples 2-1 to 2-2 and Examples 2-3 to 2-8, when (A) alkali-soluble polyamidoimide resin was blended in more amount than (E) alkali-soluble polyimide resin It was shown that heat resistance was further improved. In addition, from the comparison between Example 2-3 and Examples 2-7 to 2-8, (D) by using a cellulose derivative containing a group represented by formula (6), the stickability is further reduced, that is, the stickability is improved. I found that the evaluation results were getting better. Furthermore, from the comparison between Example 2-3 and Example 2-6, (A) an alkali-soluble polyamideimide resin, which has a structure represented by formula (1) and a structure represented by formula (2), is It was found that flexibility and adhesion properties were also improved by using mid resin.

Claims (14)

A curable resin composition capable of alkali development and forming a cured film by exposure and heat treatment,
When a dry coating film with a thickness of 2 to 100 μm is formed from the curable resin composition, the arithmetic average roughness Ra of the dry coating film is less than 0.1 μm, and the arithmetic average roughness Ra of the cured coating film after heat curing of the dry coating film is A curable resin composition characterized by being 0.1 μm or more and 1 μm or less. The method of claim 1, wherein when a dry coating film having a thickness of 2 to 100 μm is formed from the curable resin composition, the arithmetic mean roughness Ra of the dry coating film is less than 0.05 μm, and the cured coating film after thermal curing of the dry coating film A curable resin composition characterized in that the arithmetic mean roughness Ra is 0.1 ㎛ or more and 0.5 ㎛ or less. The method according to claim 1 or 2, comprising (A) an alkali-soluble polyamideimide resin, (B) a photobase generator, (C) a thermosetting compound, and (D) a cellulose derivative. Curable resin composition. The curable resin composition according to claim 3, wherein the thermosetting compound (C) is an epoxy resin. A laminated structure wherein at least one side of a resin layer formed from the curable resin composition according to claim 1 is supported or protected by a film. A cured product of the curable resin composition according to claim 1 or the resin layer according to claim 5. An electronic component characterized by having an insulating film containing the cured product according to claim 6. (A) an alkali-soluble polyamideimide resin,
(B) a photobase generator,
(C) a thermosetting compound,
(D) Cellulose derivatives
A curable resin composition comprising: The curable resin composition according to claim 8, wherein the alkali-soluble polyamideimide resin (A) has a carboxyl group. The curable resin composition according to claim 9, wherein the alkali-soluble polyamideimide resin (A) has a carboxyl group and a phenolic hydroxyl group. The curable resin composition according to claim 8, further comprising (E) an alkali-soluble polyimide resin. The curable resin composition according to claim 8, wherein the thermosetting compound (C) is an epoxy resin. A cured product obtained from the curable resin composition according to claim 8. An electronic component comprising an insulating film containing the cured product according to claim 13.