TWI658323B - Alkali-developed photocurable thermosetting resin composition and printed wiring board using the same - Google Patents

Abstract

The present invention provides an insulating film for a flexible printed wiring board having excellent flexibility and workability, and particularly an alkali-developed photocurable heat suitable for a one-time forming process of a bent portion (bent portion) and a mounting portion (non-bent portion). A curable resin composition.

The present invention is an alkali-developing photocurable thermosetting resin composition, which comprises a urethane resin having a carboxyl group, a resin having a carboxyl group other than the urethane resin, a photobase generator, and Heat hardening composition. The urethane resin having a carboxyl group is preferably one having an ethylenically unsaturated group. Moreover, it is preferable to contain the monomer which has an ethylenically unsaturated group.

Description

Alkali-developed photocurable thermosetting resin composition and printed wiring board using the same

The present invention relates to an alkali-developing photocurable thermosetting resin composition and a flexible printed wiring board. Specifically, the present invention relates to an alkali-developing photocurable thermosetting resin composition and a flexible printed wiring board. Specifically, the present invention relates to alkali-developing, has excellent flexibility, and suppresses occurrence of sags during heat treatment after development. In particular, an alkali-developing photocurable thermosetting resin composition having good deep-curing properties and excellent pattern formation properties, and a flexible printed wiring board provided with the cured product of the alkali-developing photocurable thermosetting resin composition.

In recent years, the popularity and performance improvement of smart phones or tablet terminals has been rapidly developed. Consumers have increased their requirements for the miniaturization and thinness of the information equipment terminals represented by them. In order to respond to these requirements, it is necessary to increase the density and space-saving of circuit boards inside products. Therefore, the use of a flexible printed wiring board that can be folded and stored and can increase the degree of freedom of circuit configuration has been expanded, and the reliability of the flexible printed wiring board is also required to be higher than that so far.

At present, in order to ensure the insulation reliability of a flexible printed wiring board, it has been widely used in bending portions (curved portions). A mixing process using a polyimide as a base material and a photosensitive resin composition in a mounting portion (non-curved portion) (see Patent Documents 1 and 2). Polyimide has excellent mechanical properties such as heat resistance and bendability. On the other hand, the photosensitive resin composition used in the mounting portion has characteristics such as excellent electrical insulation and solder heat resistance and can be finely processed.

In the past, a covering material using polyimide as a substrate had to be processed by die stamping, so it was not suitable for fine wiring. For this reason, the die-attachment portion of the fine wiring is required, and it can be partially used in combination with an alkali-developing photosensitive resin composition (solder resist) processed by lithography. When this resin composition is used differently in the manufacture of flexible printed wiring boards, there are problems of poor cost and workability due to the two steps of a step of laminating a cover material and a step of forming a solder resist.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 62-263692

Patent Document 2: Japanese Patent Application Laid-Open No. 63-110224

So far, a review of covering materials without a mix and match process has been conducted. For example, the application of a photosensitive resin composition for a solder resist as a cover material for a flexible printed wiring board has been reviewed. However, the reliability of the resin composition for a solder resist as a cover material is not as high as the impact resistance or bendability. foot. The resin composition for a solder resist is also hardened and shrunk with the photopolymerization of acrylic, so there is also a problem of dimensional stability such as warpage of a flexible wiring board.

Therefore, an object of the present invention is to provide an insulating film for a flexible printed wiring board having excellent bendability and workability, particularly an alkali-developed type suitable for one-time forming process of a bent portion (bent portion) and a mounting portion (non-bent portion). Photocurable thermosetting resin composition.

As a result of an intensive review by the present inventors in order to solve the above problems, it was found that a resin composition containing a urethane resin having a carboxyl group, a photobase generator, and a thermosetting component can solve the above problems.

That is, it was found that the photo-alkali generator is activated by light irradiation, and the generated alkali is used as a catalyst to cause an addition reaction of the urethane resin having a carboxyl group with a thermosetting component by heating, whereby the alkali solution can be used only Remove unexposed parts. Therefore, it is possible to perform fine processing by alkali development, and since a urethane resin is contained, a cured product having excellent flexibility can be expected.

However, when a composition containing a urethane resin having a carboxyl group, a thermosetting component, and a photobase generator is developed after light irradiation, and then heat-cured, it is confirmed that the resin will elute due to heating, resulting in the so-called Collapse causes the pattern to collapse.

Then, the present inventors repeated further review and found that in addition to the above components, the above problems can be solved by containing a resin having a carboxyl group other than the urethane resin, and thus the present invention has been completed. And, at the same time, Blending a monomer having an ethylenically unsaturated group into the above composition, or using a monomer having an ethylenically unsaturated group as the aforementioned urethane resin having a carboxyl group is more desirable because it can further prevent the occurrence of sag.

On the other hand, as is clear from the above, there is still room for improvement of deep hardenability when performing microfabrication by alkali development using an addition reaction of a base generated by light irradiation as a catalyst. In particular, when an alkali-developing resin composition is used in a layer close to a substrate in a cover material of a multilayer structure, the resin or photosensitizer contained in the upper layer may absorb light, and the light may not sufficiently reach the deep part of the resin layer.

Therefore, the present inventors repeated further review and found that the use of an oxime ester-based photobase generator having a specific structure as the photobase generator can solve the above problems. In addition, it was found that, in the heat-curing reaction after light irradiation of the alkali-developing photocurable thermosetting resin composition, the selection range of the heating temperature or heating time can be widened, and the resin composition having better workability can be obtained.

The present invention is the following [1] to [9].

[1] An alkali-developing photocurable thermosetting resin composition, comprising a urethane resin having a carboxyl group, a resin having a carboxyl group other than the urethane resin, a photobase generator, and Heat hardening composition.

[2] The alkali-developing photocurable thermosetting resin composition according to [1], wherein the photobase generator contains an oxime ester photobase generator having a group represented by the following general formula (1),

(Wherein R ¹ represents a hydrogen atom, an unsubstituted or substituted alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen atom substituted phenyl group, an unsubstituted or substituted 1 or more hydroxyl group having 1 to 20 carbon atoms Alkyl, this alkyl interrupted by one or more oxygen atoms, unsubstituted or cycloalkyl having 5 to 8 carbons substituted with alkyl or phenyl with 1 to 6 carbon atoms, unsubstituted or substituted with 1 carbon ~ 6 alkyl or phenyl substituted alkanoyl or benzamidine having 2 to 20 carbons, R ² represents unsubstituted or phenyl substituted with alkyl having 1 to 6 carbons, phenyl or halogen atom, An unsubstituted or substituted alkyl group having 1 to 20 carbon atoms with one or more hydroxyl groups, an alkyl group interrupted with one or more oxygen atoms, an unsubstituted or substituted alkyl group with 1 to 6 carbon atoms or a phenyl group (Cycloalkyl with 5 to 8 carbon atoms, unsubstituted or substituted with alkyl or phenyl with 1 to 6 carbon or 2 to 20 carbon or alkyl benzyl).

[3] The alkali-developing photocurable thermosetting resin composition according to [1], wherein the urethane resin having a carboxyl group is an ethylenically unsaturated group.

[4] The alkali-developing photocurable thermosetting resin composition according to [1], further comprising a monomer having an ethylenically unsaturated group.

[5] The alkali-developing photocurable thermosetting resin composition according to [1], wherein the thermosetting component is a cyclic ether compound.

[6] The alkali-developing photocurable thermosetting resin composition according to [1], which is a cover material and a user of the adhesive layer.

[7] A dry film characterized by having an alkali developing type such as [1] A resin layer obtained by applying a photocurable thermosetting resin composition and drying it.

[8] A hardened material characterized by hardening an alkali-developing photocurable thermosetting resin composition such as [1], or hardening a dry film such as [7].

[9] A flexible printed wiring board characterized by being provided with a hardened body as in [8].

According to the present invention, there can be provided an alkali-developing photocurable thermosetting resin composition that suppresses occurrence of sags during heat curing after development. In addition, it can provide an insulating film for a flexible printed wiring board with excellent flexibility, especially an alkali-developed photocuring thermosetting property suitable for a one-time forming process of a bent portion (bent portion) and a mounting portion (non-bent portion). A resin composition and a printed wiring board provided with the cured product. In addition, the alkali-developing photocurable thermosetting resin composition of the present invention is easy to manage the temperature and time during heat curing after light irradiation, and has excellent workability.

The alkali-developing photocurable thermosetting resin composition of the present invention is suitable for a cover material for a flexible printed wiring board. The alkali-developing photocurable thermosetting resin composition of the present invention is also suitable as a resin composition for an adhesive layer of a cover material of a multilayer structure. Here, the adhesive layer refers to a resin layer adjacent to a flexible printed circuit board of a cover material having a laminated structure of two or more layers.

Further, by using an oxime ester-based photobase generator having a group represented by the general formula (I) as the photobase generator, deep hardening can be provided. Excellent alkali-developing photocurable thermosetting resin composition. In addition, it has a wide selection of temperature and time during heat curing after light irradiation, and is excellent in workability.

1‧‧‧flexible printed wiring substrate

2‧‧‧ Copper Circuit

3‧‧‧ resin layer

4‧‧‧ resin layer

5‧‧‧Mask

FIG. 1 is a step diagram schematically showing an example of a method for manufacturing a flexible printed wiring board according to the present invention.

The alkali-developing photocurable thermosetting resin composition of the present invention (hereinafter also referred to simply as the "resin composition of the present invention") is characterized in that it contains urethane resins having a carboxyl group, and other than urethane resins. A resin having a carboxyl group, a photobase generator, and a thermosetting component.

The resin composition of the present invention uses an alkali generated from a photo-alkali generator as a catalyst, and an urethane resin having a carboxyl group is subjected to an addition reaction with a thermosetting component by heating after exposure, and the alkali The exposed portion becomes an alkali developable resin composition.

Since a resin composition containing a urethane resin having a carboxyl group, a thermosetting component, and a photobase generator is further blended with a carboxyl group other than the above-mentioned urethane resin, heat hardening after development can be suppressed. Occurrence of slump. The detailed mechanism is not certain, but one of the reasons is considered to be that the carboxyl group in the urethane resin having a carboxyl group has low reactivity with the thermosetting component, and by formulating a resin other than the urethane resin, If there is a carboxyl group, the addition reaction during heating and hardening after development further proceeds to form a solid matrix.

In addition, from the viewpoint of suppressing the effect of sag, the resin composition of the present invention preferably contains an ethylenically unsaturated group in the system. The ethylenically unsaturated group may also be present in the above-mentioned urethane resin having a carboxyl group. For the resin composition of the present invention, a monomer having an ethylenically unsaturated group described later may also be blended, and may also be both. With the presence of ethylenically unsaturated groups, it is believed that free radical polymerization can be induced by light to form a solid matrix, and the occurrence of sags during heating and hardening after development can be suppressed.

The resin composition of the present invention is suitable for a resin insulating layer of a flexible printed wiring board, such as a covering material or a solder resist.

When the resin composition of the present invention is used to form a resin insulating layer of a flexible printed wiring board, a suitable manufacturing method is as follows. That is, the manufacturing method includes the steps of forming a resin layer made of the resin composition of the present invention on a flexible printed wiring board, irradiating the resin layer with light having a pattern shape, and heating the resin layer. (Post Exposure Bake: also known as PEB), and a step of subjecting the resin layer to alkali development to form a resin insulating layer having a pattern. If necessary, after alkali development, light irradiation or heat curing (post-curing) is performed to completely cure the resin composition to obtain a highly reliable resin insulating layer.

As described above, the resin composition of the present invention is more preferably a one that can form a negative pattern by alkali development by subjecting a carboxyl group to a thermosetting component to undergo an addition reaction by a heat treatment after selective light irradiation.

Since the obtained hardened material is excellent in heat resistance and bendability, The development is finely processed. Therefore, it is not necessary to use a photosensitive resin composition of the alkali development type in part, and it can be used in any of the bent portion (curved portion) and the mounting portion (non-curved portion) of a flexible printed circuit board It is suitable for one-time forming process of the bent portion (curved portion) and the mounting portion (non-curved portion).

As described above, the carboxyl group in the urethane resin is low in reactivity. Compared with other resins containing only carboxyl group, the heat curing reaction after exposure (in the PEB step) can be performed at the same heating temperature. The time taken for the addition reaction to become alkali-resistant is extended. In addition, it is possible to widen the selection range of the heating temperature during the heat-hardening reaction (during the PEB step). This improves the workability and operability of the resin composition. It is also possible to make the unexposed portion resistant to alkali, and to suppress the occurrence of so-called overexposure.

Hereinafter, each component will be described in detail.

[Urethane resin with carboxyl group]

As the urethane resin having a carboxyl group contained in the resin composition of the present invention, a conventional and commonly used urethane resin compound containing a carboxyl group in a molecule can be used. In addition, as described above, from the viewpoint of improving the effect of preventing sag during heating, a carboxyl group-containing urethane resin having an ethylenically unsaturated double bond in the molecule is preferred. Here, the so-called sag refers to a phenomenon in which, when the resin composition is irradiated with light and then developed and hardened by heating, the resin dissolves out by heating and the pattern collapses. As for the ethylenically unsaturated double bond, one derived from (meth) acrylic acid or a (meth) acrylic acid derivative is preferred. Specific examples of the urethane resin having a carboxyl group include the compounds listed in the following (1) to (4) (which may be oligomers and polymers) Either).

(1) Diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates, and carboxyl-containing diisocyanates such as dimethylolpropionic acid and dimethylolbutanoic acid Alcohol compounds and polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct glycols, and phenolic properties A carboxyl group-containing urethane resin obtained by a polyaddition reaction of a diol compound such as a hydroxyl group and an alcoholic hydroxyl compound.

(2) Diisocyanate with bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bixylenol epoxy resin Photosensitive carboxyl-containing compounds obtained by polyaddition reaction of (meth) acrylic acid esters of bifunctional epoxy resins such as biphenol epoxy resins or partial acid anhydride modifiers thereof, diol compounds containing carboxyl groups, and glycol compounds Urethane resin.

(3) Adding a compound having one hydroxyl group and one or more (meth) acrylic acid groups in the molecule, such as hydroxyalkyl (meth) acrylate, to the resin synthesis of the above (1) or (2), and the terminal is Acrylated photosensitive urethane resin containing a carboxyl group.

(4) In the resin synthesis of the above (1) or (2), a mole reactant such as isophorone diisocyanate and pentaerythritol triacrylate is added, and the molecule has one isocyanate group and one or more (a A (meth) acrylic-based compound having a (meth) acrylic acid-terminated photosensitive carboxyl group-containing urethane resin.

The urethane resin having a carboxyl group preferably has an acid value of 20 to 200 mgKOH / g, and more preferably 40 to 150 mgKOH / g. When the acid value is within the above range, alkali solubility is good, and patterning by alkali development becomes easy.

The mass average molecular weight of the urethane resin having a carboxyl group is preferably 1,000 to 100,000, and more preferably 3,000 to 50,000. When the mass average molecular weight is 1,000 or more, sufficient flexibility of the cured product can be obtained. When the mass average molecular weight is 100,000 or less, alkali developability is improved.

The blending amount of the urethane resin having a carboxyl group is preferably 10 parts by mass or more in a total of 100 parts by mass of the urethane resin having a carboxyl group and a resin having a carboxyl group other than the urethane resin. It is preferably at least 30 parts by mass. By blending 10 parts by mass or more, the flexibility is improved.

[Resin having carboxyl group other than urethane resin]

The resin having a carboxyl group other than the urethane resin contained in the resin composition of the present invention is a resin other than the above-mentioned urethane resin having a carboxyl group, and a resin having a carboxyl group in a molecule. As this resin, a conventional resin compound containing a carboxyl group in a molecule can be used. It may also be a resin having an ethylenically unsaturated double bond in the molecule. As for the ethylenically unsaturated double bond, one derived from (meth) acrylic acid or a (meth) acrylic acid derivative is preferred.

Specific examples of the resin other than the urethane having a carboxyl group are the compounds listed in the following (5) to (11) (may be oligomers and polymers) Any of the things).

(5) Contained by copolymerization of unsaturated carboxylic acids such as (meth) acrylic acid and unsaturated group-containing compounds such as styrene, α-methylstyrene, lower alkyl (meth) acrylate, isobutylene, etc. Carboxyl resin.

(6) A photosensitive carboxyl group-containing resin in which a difunctional or higher polyfunctional (solid) epoxy resin is reacted with (meth) acrylic acid to add a dibasic acid anhydride to a hydroxyl group present on a side chain.

(7) Photosensitivity of a polyfunctional epoxy resin that further epoxidizes the hydroxyl group of a bifunctional (solid) epoxy resin with (meth) acrylic acid with epichlorohydrin and the addition of a dibasic acid anhydride to the generated hydroxyl Carboxyl-containing resin.

(8) A bifunctional oxetane resin is reacted with a dicarboxylic acid, and a dibasic acid anhydride is added to a 1-hydroxyl-containing carboxyl-containing polyester resin.

(9) A reaction obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide and propylene oxide and / or a cyclic carbonate compound such as ethylene carbonate and propylene carbonate The product is partially esterified with an unsaturated monocarboxylic acid containing a carboxyl group, and the obtained reaction product is reacted with a polybasic acid anhydride to obtain a carboxyl group-containing photosensitive resin.

(10) Obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide and propylene oxide and / or a cyclic carbonate compound such as ethylene carbonate and propylene carbonate. A carboxyl group-containing resin obtained by reacting a reaction product with a polybasic acid anhydride.

(11) Addition of the above resins (5) to (10) to a compound having one epoxy group and one or more (meth) acrylic groups in one molecule Resin containing photosensitive carboxyl group.

The resin having a carboxyl group other than the urethane resin has an acid value of preferably 20 to 200 mgKOH / g, and more preferably 40 to 150 mgKOH / g. When the acid value is within the above range, alkali solubility is good, and patterning by alkali development becomes easy.

The mass average molecular weight of the resin having a carboxyl group other than the urethane resin is preferably 1,000 to 100,000, and more preferably 3,000 to 50,000. When the molecular weight is within the above range, alkali solubility is good, and patterning by alkali development becomes easy.

The blending amount of the resin having a carboxyl group other than the urethane resin is preferably 5 parts by mass out of a total of 100 parts by mass of the total of the urethane resin having a carboxyl group and the resin having a carboxyl group other than the urethane resin. The above is more preferably 20 parts by mass or more. By blending 5 parts by mass or more when heating after light irradiation (PEB step), the development resistance of the exposed portion can be obtained at a low temperature or in a short time.

[Photo-alkali generator]

The photobase generator used in the present invention changes the molecular structure when irradiated with light such as ultraviolet rays or visible light, or generates a catalyst that acts as an addition reaction between a carboxyl group and a heat-curing component described later by molecular cracking. A compound of more than one basic substance that functions. Examples of the basic substance include a secondary amine and a tertiary amine.

When the resin composition of the present invention has an ethylenically unsaturated group in the system, the polymerization reaction of the ethylenically unsaturated group can be initiated by light irradiation. Therefore, among photo-alkali generators, those that function as photo-radical polymerization initiators that generate radicals in the process of activation by light irradiation are preferred.

Examples of the photobase generator include an α-aminoacetophenone compound, an oxime ester compound, or an alkoxyimine group, an N-formamated aromatic amine group, an N-fluorinated aromatic amine group, Compounds having substituents such as a nitrobenzylcarbamate group and an alkoxybenzylcarbamate group. Among them, oxime ester compounds and α-aminoacetophenone compounds are preferred. As for the α-aminoacetophenone compound, those having two or more nitrogen atoms are preferred.

As other photobase generators, WPBG-018 (trade name: 9-anthrylmethyl N, N'-diethylcarbamate), WPBG-027 (trade name: (E) -1- [ 3- (2-hydroxyphenyl) -2-propenyl) piperidine), WPBG-082 (brand name: guanidinium 2- (3-benzylphenyl) propionate), WPBG-140 (commercial product Name: 1- (anthraquinone-2-yl) ethylimidazole carboxylate) and the like.

The α-aminoacetophenone compound has a benzoin ether bond in the molecule and is irradiated with light to cause cracking in the molecule, thereby generating an alkaline substance (amine) that functions as a hardening catalyst. As a specific example of the α-aminoacetophenone compound, (4-morpholinylbenzylfluorenyl) -1-benzyl-1-dimethylaminopropane (Irgacure 369, trade name, manufactured by BASF, Japan) or 4 can be used. -(Methylthiobenzylfluorenyl) -1-methyl-1-morpholinylethane (Irgacure 907, trade name, manufactured by BASF, Japan), 2- (dimethylamino) -2-[(4- A commercially available compound such as methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone (Irgacure 379, trade name, manufactured by BASF, Japan) or a solution thereof.

Any oxime ester compound can be used as long as it is a compound that generates a basic substance by irradiation with light. Examples of the oxime ester compound include CGI-325, Irgacure-OXE01, Irgacure-OXE02, N-1919, NCI-831, manufactured by ADEKA, and the like as commercially available products. In addition, a compound having two oxime ester groups in the molecule described in Japanese Patent No. 4,344,400 can also be used.

In addition, Japanese Patent Application Laid-Open No. 2004-359639, Japanese Patent Application Laid-Open No. 2005-097141, Japanese Patent Application Laid-Open No. 2005-220097, Japanese Patent Application Laid-Open No. 2006-160634, Japanese Patent Application Laid-Open No. 2008-094770, The carbazoxime 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.

This photobase generator may be used individually by 1 type, and may be used in combination of 2 or more type. The blending amount of the photobase generator in the resin composition of the present invention is preferably 0.1 to 40 parts by mass, and more preferably 0.1 to 30 parts by mass relative to 100 parts by mass of the thermosetting component. When it is 0.1 parts by mass or more, the contrast of the development resistance of the light-irradiated portion / non-irradiated portion can be obtained satisfactorily. Moreover, when it is 40 mass parts or less, hardened | cured material characteristics will improve.

In the present invention, as described above, an oxime ester-based photobase generator having a structure represented by the following general formula (I) is preferably used. The oxime ester-based photobase generator is one or more types of basic which function as a catalyst for the addition reaction of a carboxyl group with a heat-curing component described later by irradiating light with ultraviolet or visible light or the like. Compounds of matter. Examples of the basic substance include primary amine, secondary amine, and tertiary amine.

When an oxime ester-based photobase generator having a structure represented by the general formula (I) is used as the photobase generator, the resin composition has better deep hardening properties than when other photobase generators are used. In addition, since the oxime ester-based photobase generator generates both radicals and bases by irradiation with light, even when radical polymerization such as ethylenically unsaturated groups is contained in the resin composition system, other than the photobase generator, There is no need for a photo-containing radical polymerization initiator. As a result, it is possible to avoid the problem that a sufficient amount of light cannot reach the deep part due to both the photo-containing radical polymerization initiator and the photobase generator. Based on the above, by using an oxime ester-based photobase generator, it can be sufficiently hardened to a deep portion, and a pattern having a good cross-sectional shape can be formed.

In addition, when an oxime ester-based photobase generator having a structure represented by the general formula (I) is used, it is possible to widen the selection range of the heating time at the same heating temperature during the heat curing reaction after exposure (in the PEB step) . This improves the workability and operability of the resin composition.

By using an oxime ester-based photobase generator having a structure represented by the general formula (I) as the photobase generator, it is possible to improve deep hardening properties and increase the time management range of PEB. In addition, by using an oxime ester-based photobase generator, it is possible to suppress the occurrence of so-called thermal overexposure, which is caused by an addition reaction that is undesired and cannot be developed. The detailed reason is not certain. The reason for this is that the oxime ester photobase generator having a structure represented by the general formula (I) does not generate a base in the state of no light irradiation, and undergoes molecular cracking by light irradiation and starts to generate. Alkali. Based on this, for example, an unexposed portion does not undergo an addition reaction using a base as a catalyst. On the other hand, it is considered that even a photo-alkali generator has the property of making the alkalinity stronger by changing the three-dimensional structure by light irradiation. The compound originally has a base such as an amine in the molecule, and it also causes an addition reaction in the unexposed portion. In this case, the difference between the hardening degree of the resin composition due to the addition reaction between the exposed portion and the unexposed portion is small, and a clear contrast cannot be obtained by alkali development, and thermal overexposure may occur.

(In the formula, R ¹ represents a hydrogen atom, an unsubstituted or alkyl group having 1 to 6 carbon atoms, a phenyl group or a phenyl group substituted with a halogen atom, an unsubstituted group or a carbon group having 1 to 20 carbon atoms. Alkyl group interrupted by one or more oxygen atoms, unsubstituted or alkyl group having 1 to 6 carbon atoms or cycloalkyl group having 5 to 8 carbon atoms substituted with phenyl group, unsubstituted or carbon number 1 ~ 6 alkyl or alkynyl or benzamidine having 2 to 20 carbon atoms substituted with phenyl, R ² represents unsubstituted or benzene having 1 to 6 carbons, phenyl, or benzene substituted with halogen atom An unsubstituted or unsubstituted or substituted alkyl group having 1 to 20 carbon atoms, an alkyl group interrupted with one or more oxygen atoms, an unsubstituted or unsubstituted alkyl group having 1 to 6 carbon atoms, or a phenyl group (Cycloalkyl substituted with 5 to 8 carbons, unsubstituted or alkyl with 1 to 6 carbons, or alkylalkyl or benzylfluorenyl with 2 to 20 carbons substituted with phenyl).

The commercially available product as an oxime ester-based photobase generator is as described above. In addition, a photopolymerization initiator having two oxime ester groups in the molecule can also be suitably used, and specifically, an oxime ester compound having a carbazole structure represented by the following general formula can be used.

(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, and a phenyl group (an alkyl group having 1 to 17 carbon atoms and 1 to 8 carbon atoms) Alkoxy, amine, alkylamino or dialkylamino substituted with alkyl having 1 to 8 carbon atoms), naphthyl (alkyl having 1 to 17 carbon atoms, alkyl having 1 to 8 carbon atoms (Oxy group, amine group, alkylamino group or dialkylamino group having an alkyl group having 1 to 8 carbon atoms), Y and Z each represent a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, and 1 to 1 carbon atoms 8 alkoxy, halo, phenyl, phenyl (alkyl with 1 to 17 carbons, alkoxy with 1 to 8 carbons, amine, alkyl with 1 to 8 carbons Substituted by amine or dialkylamino), naphthyl (alkyl with 1 to 17 carbons, alkoxy with 1 to 8 carbons, amine, alkyl amine with alkyl with 1 to 8 carbons Or dialkylamino), anthracenyl, pyridyl, benzofuranyl, benzothienyl, Ar represents a bond, or an alkylene, vinylene, phenylene, or ethylene Biphenyl, pyridyl, naphthyl, thiophene, anthracenyl, thienyl, furfuryl, 2,5-pyrrolediyl, 4,4'-stilbyl-diyl, 4,2 ' -Styrene-diyl, n is 0 Or an integer of 1).

In particular, in the aforementioned general formula, X and Y are methyl or ethyl, Z is methyl or phenyl, n is 0, and Ar is preferably bonded, or phenyl, naphthyl, thiophene, or thiophene. base.

In addition, a compound represented by the following general formula may be mentioned Preferred carbazoxime ester compounds.

(In the formula, R ¹¹ represents an alkyl group having 1 to 4 carbon atoms, or a phenyl group which can be substituted with a nitro group, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and R ¹² represents an alkyl group having 1 to 4 carbon atoms Alkyl group, alkoxy group having 1 to 4 carbon atoms, or phenyl group which can be substituted by alkyl group or alkoxy group having 1 to 4 carbon atoms, R ¹³ represents that it can be connected by oxygen atom or sulfur atom, and can be connected by benzene Alkyl substituted with 1 to 20 carbon atoms, benzyl substituted with alkoxy having 1 to 4 carbon atoms, R ¹⁴ represents nitro, or X ¹ -C (= O)- X ¹ represents an aryl group, a thienyl group, a morpholinyl group, a thiophenyl group, or a structure represented by the following formula that may be substituted with an alkyl group having 1 to 4 carbon atoms.

Moreover, the carbazoxime ester compound etc. which were described in the said gazette can also be used.

The oxime ester-based photobase generator may be used singly or in combination of two or more kinds. The amount of the photo-alkali generator contained in the alkali-developing photo-curable thermosetting resin composition is 100 masses relative to the thermosetting component. It is preferably 0.1 to 40 parts by mass, and more preferably 0.1 to 30 parts by mass. When the content is 0.1 parts by mass or more, the contrast of the development resistance between the light-irradiated portion and the unilluminated portion can be obtained satisfactorily. Moreover, when it is 40 mass parts or less, hardened | cured material characteristics will improve.

[Photo radical polymerization initiator]

In addition to the photobase generator described above, the resin composition of the present invention may contain a photoradical polymerization initiator as long as the effect of the present invention is not impaired. As the photo-radical polymerization initiator, a conventional photo-radical polymerization initiator that generates radicals by light irradiation can be used. For example, the benzophenone-based photopolymerization initiator other than the α-aminoacetophenone-based photopolymerization initiator that functions as the photobase generator described above, fluorenyl phosphine oxide-based photopolymerization initiator, and titanocene-based Photopolymerization initiators and the like.

Examples of the benzophenone-based photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-one, 2- Hydroxy-2-methyl-1-phenyl-propane-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1 -Ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propanyl) -benzyl] phenyl} -2-methyl-propane-1-one, and the like.

Specific examples of the fluorenylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzylfluorenyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzylfluorenyl) -phenyl group. Phosphine oxide, bis (2,6-dimethoxybenzylfluorenyl) -2,4,4-trimethyl-pentylphosphine oxide, etc. Commercially available products are LUCIRIN TPO manufactured by BASF Japan, Irgacure 819 manufactured by BASF Japan, and the like.

The blending amounts of these benzophenone-based photopolymerization initiators and fluorenylphosphine oxide-based photopolymerization initiators are relative to those of urethane resins having a carboxyl group and resins having a carboxyl group other than the urethane resin. The total amount is 100 parts by mass, preferably 0.01 to 15 parts by mass. If it is less than 0.01 parts by mass, the photocurability is insufficient, and the coating film properties such as chemical resistance may be reduced. On the other hand, if it exceeds 15 parts by mass, the effect of reducing outgassing cannot be obtained, and further, the light absorption on the surface of the coating film becomes drastic, and there is a tendency that the deep hardenability decreases. More preferably, it is 0.5 to 10 parts by mass.

Examples of the titanocene-based photopolymerization initiator include bis (cyclopentadienyl) -diphenyl-titanium, bis (cyclopentadienyl) -dichloro-titanium, and bis (cyclopentadienyl). -Bis (2,3,4,5,6-pentafluorophenyl) titanium, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyrrole-1-yl) phenyl) Titanium, etc. Commercially available products include Irgacure 784 manufactured by BASF Japan.

The blending amount of the titanocene-based photopolymerization initiator is 100 parts by mass with respect to the total amount of the urethane resin having a carboxyl group and the resin having a carboxyl group other than the urethane resin, preferably 0.01 to 15 mass Serving. If it is less than 0.01 parts by mass, the light hardening on copper is insufficient, and the coating film may be peeled off, and coating film characteristics such as chemical resistance may be reduced. On the other hand, when it exceeds 15 parts by mass, the amount of light absorption becomes too high, and the deep hardenability may be deteriorated. More preferably, it is 0.5 to 10 parts by mass.

In addition to the above-mentioned photopolymerization initiator, a photoinitiator and a sensitizer may be used. Examples of the photopolymerization initiator, photoinitiator, and sensitizer that can be used in the photosensitive resin composition include benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, and ketal compounds. ,two Benzophenone compounds, tertiary amine compounds, and xanthone compounds.

Specific examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether.

Specific examples of the acetophenone compound include acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 1,1 -Dichloroacetophenone and the like.

Specific examples of the anthraquinone compound include 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, and 1-chloroanthraquinone.

Specific examples of the thioxanthone compound include 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, and the like .

Specific examples of the ketal compound include acetophenone dimethyl ketal and benzyl dimethyl ketal.

Specific examples of the benzophenone compound include benzophenone, 4-benzylfluorenyldiphenylsulfide, 4-benzylfluorenyl-4'-methyldiphenylsulfide, and 4-benzylfluorenyl-4. '-Ethyldiphenylsulfide, 4-benzylfluorenyl-4'-propyldiphenylsulfide, and the like.

Examples of the tertiary amine compound include, for example, an ethanolamine compound and a compound having a dialkylaminobenzene structure. For example, a commercially available product is 4,4'-dimethylaminobenzophenone (NISSOCURE manufactured by Soda Corporation, Japan). -MABP), 4,4'-diethylaminobenzophenone (EAB manufactured by Hodogaya Chemical Co., Ltd.), and other dialkylaminobenzophenones, 7- (diethylamino) -4-methyl Dialkylamino group-containing coumarin compounds such as 2-H-2-benzopyran-2-one (7- (diethylamino) -4-methylcoumarin), 4-dimethyl Ethyl aminobenzoate (KYACURE-EPA manufactured by Nippon Kayaku Co., Ltd.), 2-dimethylaminobenzoic acid ethyl ester (Quantacure DMB manufactured by International Bio Synthetic), 4-dimethylaminobenzoic acid (n-butyl (Oxy) ethyl ester (Quantacure BEA, manufactured by International Bio Synthetic), isoamyl ethyl p-dimethylaminobenzoate (KYACURE-DMBI, manufactured by Nippon Kayaku Co., Ltd.), 4-dimethylaminobenzoic acid 2 -Ethylhexyl ester (Esolol 507 manufactured by Van Dyk) and the like.

Among these, a thioxanthone compound and a tertiary amine compound are preferred. In particular, when a thioxanthone-containing compound is used, it is preferred from the viewpoint of deep hardenability. Among them, preferred are thioxanthone containing 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, etc. Compound.

The blending amount of these thioxanthone compounds is 100 parts by mass with respect to the content of the urethane resin having a carboxyl group and a resin having a carboxyl group other than the urethane resin, and preferably 20 parts by mass or less. When the compounding amount of the thioxanthone compound exceeds 20 parts by mass, the film thickness hardenability decreases, and at the same time, the product cost increases. It is more preferably 10 parts by mass or less.

In addition, as the tertiary amine compound, a compound having a dialkylaminobenzene structure is preferred. Among them, a dialkylaminobenzophenone compound is particularly preferred, and the dialkylamine group containing a maximum absorption wavelength is in a range of 350 to 450 nm. Coumarin compounds and ketocoumarins.

As for the dialkylaminobenzophenone compound, 4,4'-diethylaminobenzophenone is also preferred because of its low toxicity. Since the coumarin compound containing a dialkylamino group has a maximum absorption wavelength in the ultraviolet region of 350 to 410 nm, it has less coloring and becomes a colorless and transparent hardened film. Therefore, a colored pigment can be used. A colored hardened film that reflects the color of the colored pigment itself is provided. In particular, 7- (diethylamino) -4-methyl-2H-1-benzopyran-2-one is preferred because it exhibits an excellent sensitizing effect on laser light having a wavelength of 400 to 410 nm.

The compounding amount of the tertiary amine compound is preferably 0.1 to 20 parts by mass based on 100 parts by mass of the total amount of the urethane resin having a carboxyl group and the resin having a carboxyl group other than the urethane resin. When the compounding amount of the tertiary amine compound is less than 0.1 part by mass, there is a tendency that a sufficient sensitizing effect cannot be obtained. On the other hand, when it exceeds 20 parts by mass, the light absorption on the surface of the coating film due to the tertiary amine compound becomes intense, and the deep hardenability tends to decrease. More preferably, it is 0.1 to 10 parts by mass.

The photo-radical polymerization initiator, the photo-starting aid, and the sensitizer may be used alone or as a mixture of two or more.

The total amount of the photo-radical polymerization initiator, photo-starting aid, and sensitizer is 100 with respect to the total amount of the urethane resin having a carboxyl group and the resin having a carboxyl group other than the urethane resin. The mass part is preferably 35 mass parts or less. When it exceeds 35 parts by mass, there is a tendency that the deep hardenability is reduced due to such light absorption.

〔Heat hardening component〕

The thermosetting component has a functional group capable of performing an addition reaction with a carboxyl group by heat. The thermosetting component is preferably, for example, a compound having a cyclic (thio) ether group, and examples thereof include epoxy resins and polyfunctional oxetane compounds.

The epoxy resin is a resin having an epoxy group, and any of known ones can be used. Listed as bifunctional with 2 epoxy groups in the molecule Epoxy resin, multifunctional epoxy resin with many epoxy groups in the molecule, etc. It may also be a hydrogenated bifunctional epoxy compound.

Examples of the epoxy compound include bisphenol A epoxy resin, brominated epoxy resin, novolac epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, and glycidylamine ring. Oxygen resin, hydantoin type epoxy resin, alicyclic epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin or a mixture thereof; Bisphenol S epoxy resin, bisphenol A novolac epoxy resin, tetrahydroxyphenylethane epoxy resin, heterocyclic epoxy resin, diglycidyl phthalate resin, tetraglycidyl Xylylene fluorenyl ethane resin, naphthyl-containing epoxy resin, epoxy resin having a dicyclopentadiene skeleton, glycidyl methacrylate copolymerization epoxy resin, cyclohexylmaleimide and Copolymerized epoxy resin of glycidyl methacrylate, CTBN modified epoxy resin, etc.

Examples of other liquid bifunctional epoxy resins include vinylcyclohexene diepoxide and (3 ', 4'-epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxyl. Alicyclic epoxy resins such as esters, (3 ', 4'-epoxy-6'-methylcyclohexylmethyl) -3,4-epoxy-6-methylcyclohexanecarboxylate . These epoxy resins may be used individually by 1 type, and may use 2 or more types together.

In addition, conventional compounds such as a maleimide compound, a blocked isocyanate compound, an amine resin, a benzoxazine resin, a carbodiimide resin, a cyclic carbonate compound, and an epithiol resin can be blended as the conventional compound. Heat hardening composition.

The blending amount of the thermosetting component and the above-mentioned amine group having a carboxyl group The equivalent ratio of the resin having a carboxyl group other than the ethyl formate resin and the above-mentioned urethane resin (carboxyl group: a thermally reactive group such as an epoxy group) is preferably 1: 0.1 to 1:10. By setting it as the range of this compounding ratio, developability becomes favorable, and a fine pattern can be formed easily. The above equivalent ratio is more preferably 1: 0.2 to 1: 5.

[Photosensitive monomer]

The resin composition of the present invention may contain a monomer (referred to as a photosensitive monomer) having an ethylenically unsaturated group. The photosensitive monomer is a compound having one or more ethylenically unsaturated groups in the molecule. The photosensitive monomer is a person who assists the polymerization reaction of the ethylenically unsaturated group by irradiation with active energy rays. The presence of ethylenically unsaturated groups causes radical polymerization by light to form a strong matrix, which can suppress the occurrence of sags during heating and hardening after development. The ethylenically unsaturated group is preferably one derived from a (meth) acrylate.

Examples of the compound used as the photosensitive monomer include conventionally known polyester (meth) acrylates, polyether (meth) acrylates, urethane (meth) acrylates, and carbonates (meth). Acrylate, epoxy (meth) acrylate, and the like. Specific examples include hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; Acrylamines such as N, N-dimethylacrylamide, N-hydroxymethylacrylamide, N, N-dimethylaminopropylacrylamide; N, N-dimethylamine acrylic acid Ethyl acrylate, N, N-dimethylaminopropyl acrylate and other amine alkyl acrylates; hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol Polyols such as alcohols, ginsyl-hydroxyethyl isocyanurates, or polyacrylates such as ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts; benzene Polyoxy acrylates, bisphenol A diacrylates, and polyacrylates of ethylene oxide adducts or propylene oxide adducts of these phenols; glycerol diglycidyl ether, glycerol Polyacrylic acid esters of glycidyl ethers such as triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; not limited to the foregoing, polyether polyols and polycarbonates are listed. Polyols such as alcohols, hydroxyl-terminated polybutadiene, polyester polyols, etc. are directly acrylated, or acrylates and melamine acrylates are acrylated with urethane through diisocyanate, and the corresponding acrylates Each methacrylate is at least one or the like.

Alternatively, a polyfunctional epoxy resin such as a cresol novolac epoxy resin and an epoxy acrylate resin in which acrylic acid reacts with acrylic acid can be used as the photosensitive monomer. This epoxy acrylate-based resin can improve the photo-curability without reducing the touch drying property.

The compounding amount of the compound having an ethylenically unsaturated group in the molecule used as the aforementioned photosensitive dry body is 100 with respect to the total amount of the urethane resin having a carboxyl group and the resin having a carboxyl group other than the urethane resin. The proportion by mass is preferably 1 to 50 parts by mass, and more preferably 3 to 30 parts by mass. When the blending amount is less than 1 part by mass, a sufficient effect of preventing sag cannot be obtained. On the other hand, when it exceeds 50 parts by mass, the cured film may become brittle.

(Polymer resin)

In the resin composition of the present invention, conventionally known polymer resins may be blended for the purpose of improving the flexibility and touch-dryness of the obtained hardened material. Examples of the polymer resin include polymerization of cellulose-based, polyester-based, phenoxy resin-based polymers, polyethylene acetal-based, polyvinyl butyral-based, polyamine-based, and polyamine-imide-based adhesives. Materials, block copolymers, elastomers, etc. These polymer resins may be used singly or in combination of two or more kinds.

(Inorganic filler)

An inorganic filler can be blended in the resin composition of the present invention. The inorganic filler is used in order to suppress the hardening shrinkage of the hardened material of the resin composition, and to improve properties such as adhesion and hardness. Examples of the inorganic filler include barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, and nitride. Aluminum, boron nitride, Neuburg Siliceous Earth, etc. The said inorganic filler may be used individually by 1 type, and may use 2 or more types together.

(Colorant)

Furthermore, a colorant may be blended in the resin composition of the present invention. As the colorant, conventionally used coloring agents such as red, blue, green, yellow, white, and black may be used, and any of pigments, dyes, and pigments may be used.

(Organic solvents)

In the resin composition of the present invention, for the preparation of the resin composition, or Organic solvents can be used to adjust the viscosity of coating on the substrate or carrier film.

Examples of the organic solvent include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. This organic solvent may be used individually by 1 type, and may be used in mixture of 2 or more type.

(Other optional ingredients)

In the resin composition of the present invention, components such as a thiol compound, an adhesion promoter, an antioxidant, and an ultraviolet absorber can be further blended as necessary. These are known in the art of electronic materials. In addition, conventionally used conventional thickeners such as silica, hydrotalcite, organic bentonite, montmorillonite, etc., and defoamers such as silicone, fluorine, and polymer can be blended into the resin composition. Leveling agents, silane coupling agents, rust inhibitors and other commonly used additives.

〔Dry film〕

The dry film of the present invention is characterized by having a resin layer formed of the resin composition of the present invention. It may be a dry film having a multilayer structure having a layer made of a resin composition other than the resin composition of the present invention.

In the case of dry film formation, the resin composition of the present invention is diluted with an organic solvent to adjust the viscosity to a suitable thickness, and the carrier film is coated to a uniform thickness by a known method such as a corner wheel coater. Subsequently, it is usually dried at a temperature of 50 to 130 ° C for 1 to 30 minutes to form a resin layer on the carrier film.

As the carrier film, a plastic film can be used. Carrier film thickness and There is no particular limitation, but it is generally appropriately selected in the range of 10 to 150 μm. After the resin layer is formed on the carrier film, a peelable protective film may be further laminated on the surface of the resin layer.

[Flexible printed wiring board and manufacturing method thereof]

The flexible printed wiring board of the present invention is characterized by having a cured product made of a photosensitive thermosetting resin composition or a resin layer of a dry film.

The method for manufacturing a flexible printed wiring board of the present invention includes the following steps: a step of forming a resin layer made of a photosensitive thermosetting resin composition on a flexible printed wiring board, and irradiating a pattern on the resin layer A step of light, a step of heating the resin layer, and a step of subjecting the resin layer to alkali development to form at least one of a cover material and a solder resist.

[Resin layer forming step]

This step is to form at least one resin layer made of an alkali-developed photocurable thermosetting resin composition on a flexible printed circuit board.

Examples of the method for forming the resin layer include a coating method and a lamination method.

In the coating method, an alkali-developing photocurable thermosetting resin composition is applied to a flexible printed wiring board by a method such as screen printing, and dried to form a resin layer.

In the case of lamination, first, an alkali-developed photocurable thermosetting resin composition is diluted with an organic solvent to adjust the viscosity to a suitable viscosity, and the resultant is coated on a carrier film and dried to produce a dry film having a resin layer. Next, after laminating, such as a laminator, the resin layer is brought into contact with the flexible printed wiring board, and then peeled off. Off the carrier film.

In addition, the resin layer may be laminated with other layers. The other layer is preferably made of an alkali-developing photosensitive resin composition. As the alkali developing type photosensitive resin composition, a conventional composition can be used, and for example, a conventional composition for a covering material or a solder resist can be used. By forming the laminated structure including the other layers, a hardened material having more excellent impact resistance and flexibility can be obtained.

[Light irradiation step]

In this step, light is irradiated to the negative pattern shape to activate the photo-alkali generator contained in the resin layer, and the light-irradiated portion is hardened. In this step, the alkali generated in the light-irradiated portion makes the photo-alkali generator unstable, and the alkali is chemically multiplied to sufficiently harden it to the deep part of the resin layer.

As the light irradiator, a direct drawing device, a light irradiator equipped with a metal halide lamp, or the like can be used. The pattern-shaped light irradiation mask is a negative mask.

As the active energy ray used for light irradiation, laser light or scattered light having a maximum wavelength in a range of 350 to 450 nm is preferably used. By setting the maximum wavelength to this range, the photo-alkali generator can be more effectively activated. If laser light in this range is used, either a gas laser or a solid-state laser may be used. In addition, although the amount of light irradiation varies depending on the film thickness and the like, it can generally be 100 to 1500 mJ / cm ² .

[Heating step]

In this step, the light irradiation portion is heated by heating the resin layer after light irradiation. hardening. With this step, the alkali generated in the light irradiation step can be hardened to a deep portion. The heating temperature is, for example, 80 to 140 ° C. The heating time is, for example, 10 to 100 minutes.

Since the curing of the alkali-developing photocurable thermosetting resin composition in the present invention is, for example, a ring-opening reaction of an epoxy resin by a thermal reaction, it can be suppressed compared to a case of curing by a photoradical reaction. Deformation or hardening shrinkage.

[Developing step]

The developing step is to remove the non-irradiated parts by alkali development to form a negative patterned insulating film, especially a covering material and a solder resist.

The developing method may be a conventional method such as dipping. In addition, as the developing solution, sodium carbonate, potassium carbonate, potassium hydroxide, amines, imidazoles such as 2-methylimidazole, alkaline aqueous solutions such as tetramethylammonium hydroxide aqueous solution (TMAH), or a mixed solution thereof can be used.

After the development step, the insulating film may be further irradiated with light. Moreover, you may heat at 150 degreeC or more, for example.

Next, an example of a method for producing the flexible printed wiring board of the present invention from the resin composition of the present invention will be described based on the step diagram of FIG. 1. Although FIG. 1 shows a case where the resin layer has a laminated structure, it may be a case where only one layer is formed.

The lamination step in FIG. 1 is to form a laminated structure made of a resin layer 3 and a resin layer 4 on a flexible printed circuit substrate 1 on which a copper circuit 2 is formed.

The resin layer 3 is composed of a urethane resin having a carboxyl group, a resin having a carboxyl group other than the urethane resin, and a photobase generator containing the alkali-developing photocurable thermosetting resin composition of the present invention. Made.

The resin layer 4 is formed on the resin layer 3, and is made of a polyimide resin having one or more fluorene imine rings and one or more carboxyl groups in one molecule, a photobase generator, and a photosensitive heat of a thermosetting component. Made of a curable resin composition.

The light irradiation step in FIG. 1 is to arrange the mask 5 on the resin layer 4 and perform light irradiation in a negative pattern to activate the photobase generator contained in each resin layer and harden the light irradiation portion. The steps. The heating step in FIG. 1 is a step (PEB step) of curing the light irradiation portion by heating the resin layer after the light irradiation step. The developing step in FIG. 1 is a step of developing with an alkaline aqueous solution, thereby removing unirradiated portions and forming a negative pattern layer.

In addition, the second light irradiation step in FIG. 1 is a step for activating the remaining photo-alkali generating agent to generate an alkali if necessary, and the heat curing step is a step for sufficiently thermally curing the pattern layer as necessary.

[Example]

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

[Examples 1 to 6, Comparative Examples 1 to 4] <Preparation of resin composition>

Examples and comparisons were prepared according to the formulations described in Table 1 below. The materials described in the examples were pre-mixed with a blender and kneaded with a 3-axis roll mill to prepare an alkali-developed photocurable thermosetting resin composition. The values in the table are solid contents (parts by mass) unless otherwise specified.

<Formation steps of resin layer>

A flexible printed wiring substrate for forming a circuit with a copper thickness of 18 μm was prepared, and pretreatment was performed using Merck's CZ-8100. Subsequently, the resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were applied in a liquid state so that the film thickness after drying was 20 μm, and the flexible printed circuit board subjected to the aforementioned pretreatment was applied. Coating. Subsequently, it was dried in a hot-air circulation-type drying oven at 80 ° C. for 30 minutes to form a resin layer. Subsequently, light irradiation was performed with a negative pattern of HMW680GW (metal halide lamp, scattered light) of the ORC company at an exposure amount of 500 mJ / cm ² .

<Evaluation of developability according to temperature of PEB step>

The substrate having the resin layer after the exposure obtained in the resin layer forming step described above was subjected to heat treatment at 80 ° C for 60 minutes, 90 ° C for 30 minutes, and 100 ° C for 15 minutes. Subsequently, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30 ° C. and developed for 3 minutes to evaluate whether there is developability, and the width (minutes) of the heating time for development. The evaluation criteria are as follows.

○: Development is possible, and the state of the coating film is also good.

× * 1: The pattern cannot be formed because the exposed part is dissolved in the developer.

× * 2: Unexposed parts cannot be formed because they are not dissolved in the developer Pattern.

〈Evaluation of pattern shape after hardening〉

The substrate having the exposed resin layer obtained in the above-mentioned resin layer forming step was subjected to a heat treatment (PEB) at 90 ° C for 30 minutes. Subsequently, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30 ° C. for development for 3 minutes. Subsequently, it was heated at 150 ° C. for 60 minutes to evaluate whether the pattern shape after the hardening had sags. The evaluation criteria are as follows. The results obtained are shown in Table 1 below.

：: The pattern shape has no sags and is sharp.

○: The shape of the pattern is free of sags.

×: The pattern shape has sags.

From the evaluation results shown in Table 1, it is clear that even if the photosensitive thermosetting resin composition of Examples 1 to 6 is subjected to heat treatment after exposure at any temperature of 80 ° C, 90 ° C, or 100 ° C, the developability is good. . In addition, the shape of the pattern after hardening has no sag, and a sharp shape is obtained.

[Examples 7 to 14] <Preparation of resin composition>

According to the formulations described in Table 2 below, the materials described in Examples and Comparative Examples were prepared, pre-mixed with a blender, and kneaded with a 3-axis roller mill to prepare an alkali-developing photocurable thermosetting resin composition. The values in the table are solid contents (parts by mass) unless otherwise specified.

<Formation steps of resin layer>

A flexible printed wiring substrate for forming a circuit with a copper thickness of 18 μm was prepared, and pretreatment was performed using Merck's CZ-8100. Subsequently, the resin compositions of Examples 7 to 14 were applied by a liquid coating method so that the film thickness after drying became 20 μm on a flexible printed circuit board that had been subjected to the aforementioned pretreatment. Subsequently, it was dried in a hot-air circulation-type drying oven at 80 ° C. for 30 minutes to form a resin layer.

〈Developability evaluation based on time of PEB procedure〉

On the resin layer obtained through the above-mentioned step of forming the resin layer, light irradiation was performed with a negative pattern of HMW680GW (metal halide lamp, diffused light) from ORC Corporation at an exposure amount of 500 mJ / cm ² .

The substrate with the resin layer after the exposure was subjected to heat treatment at 90 ° C for 30 minutes, 60 minutes, 70 minutes, and 80 minutes, respectively. Subsequently, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30 ° C., and development was performed for 3 minutes to evaluate whether there is developability, and the heating time width (minutes) that can be developed was evaluated. The evaluation criteria are as follows.

○: Development is possible, and the state of the coating film is also good.

×: Since the unexposed part also causes a hardening reaction, the pattern cannot be formed by development.

<Preparation of composition for protective layer>

The resin composition for a protective layer used in the following pattern evaluation was prepared as follows. 100 parts by mass of polyimide having a carboxyl group with an acid value of 86 mgKOH / g Mw: 10,000, 63.5 parts by mass of jER828, and 10 parts by mass of IRGACURE OXE02 are respectively prepared. After pre-mixing with a blender, knead with a 3-axis roller to prepare Resin composition for protective layer.

`` Evaluation of pattern when used as an adhesive layer>

Using each resin composition of the examples and comparative examples, the resin composition obtained by preparing the composition for the protective layer is applied in a liquid state so that it becomes 10 μm after drying, in the above-mentioned step of forming a resin layer The obtained dried resin layer was applied on top, and dried in a hot-air circulation type drying oven at 80 ° C. for 30 minutes to form two resin layers. Subsequently, light irradiation was performed with an HMW680GW (metal halide lamp, scattered light) of the ORC company in a negative pattern at an exposure amount of 500 mJ / cm ² , and heat treatment was performed at 90 ° C. for 30 minutes. Subsequently, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30 ° C., developed for 3 minutes, and patterned. After patterning, the shape of the cross section was confirmed with an optical microscope, and the shape was evaluated.

○: Undercutting does not occur in the lower layer.

×: A large undercut occurs in the lower layer.

The results are shown in Table 2 below.

From Table 2 above, it is clear that the resin composition-based PEB steps of Examples 7 to 11 containing the oxime ester-based photobase generator having a structure represented by the general formula (I) of the present invention have a wide selection of heating time. Excellent operability.

In contrast, when the resin compositions of Examples 12 to 14 that did not contain the oxime ester-based photobase generator having a structure represented by the general formula (I) were heated at 90 ° C for 70 minutes or more, the unexposed portions were not able to be used. Pattern development is impossible with alkali development.

In addition, the resin compositions of Examples 7 to 11 exhibited sufficient deep hardenability even when they were located under the two-layer structure having a protective layer made of a resin composition that absorbs light as an upper layer.

Claims (7)

A method for manufacturing a flexible printed wiring board includes the steps of forming a resin layer formed of an alkali-developing photocurable thermosetting resin composition containing a photobase generator on a flexible printed wiring substrate , And the step of irradiating the resin layer with patterned light, generating a base from the photobase generator in the light irradiation section, and heating the resin layer, by the addition reaction using the base as a catalyst, the light The irradiated part becomes an alkali-resistant step and a step of subjecting the resin layer to alkali development to form a patterned resin insulating layer, wherein, as the alkali-developable photocurable thermosetting resin composition, it contains : Urethane resin with carboxyl group; resin with carboxyl group other than urethane resin; the aforementioned photobase generator and thermosetting component. An application of an alkali-developing photocurable thermosetting resin composition, which is used for a method of manufacturing a flexible printed wiring board including the following steps: forming a photo-alkali-containing generator on a flexible printed wiring substrate The step of the resin layer formed by the alkali-developable photocurable thermosetting resin composition, and the step of irradiating the patterned light to the resin layer, generating the alkali from the photobase generator at the light irradiation part, and heating the aforementioned A resin layer, a step of making the light irradiated portion alkali resistant by an addition reaction using the alkali as a catalyst, and a step of forming the resin insulating layer having a pattern by alkali development of the resin layer, the alkali The development type photocurable thermosetting resin composition contains: a urethane resin having a carboxyl group; a resin having a carboxyl group other than the urethane resin; a photobase generator and a thermosetting component, the aforementioned amino acid The compounding amount of the resin having a carboxyl group other than the ethyl ester resin is 100 mass in total of the aforementioned urethane resin having a carboxyl group and the resin having a carboxyl group other than the urethane resin Is 5 parts by mass or more, and the compounding amount of the photobase generator is 0.1 to 40 parts by mass relative to 100 parts by mass of the thermosetting component, and the compounding amount of the thermosetting component is the carbamic acid ethyl ester having a carboxyl group The equivalent ratio of the resin having a carboxyl group and the thermally reactive group other than the ester resin and the urethane resin is in the range of 1: 0.1 to 1:10, and the acid value of the urethane resin having a carboxyl group is 20 ~ 200mgKOH / g, the mass average molecular weight is 1,000 ~ 100,000, the acid value of the resin with carboxyl group other than the aforementioned urethane resin is 20 ~ 200mgKOH / g, and the mass average molecular weight is 1,000 ~ 100,000. The use of an alkali-developing photocurable thermosetting resin composition as claimed in item 2 of the patent scope, wherein the aforementioned photobase generator contains an oxime ester-based photobase generator having a group represented by the following general formula (1) ,

(In the formula, R ¹ represents a hydrogen atom, an unsubstituted or substituted C 1-6 alkyl group, a phenyl group or a halogen atom substituted phenyl group, an unsubstituted or substituted with one or more hydroxyl groups and a C 1-20 carbon group Alkyl group, the alkyl group interrupted by one or more oxygen atoms, unsubstituted or substituted with a C1-6 alkyl group or phenyl group, substituted with a C5-8 cycloalkyl group, unsubstituted or substituted with a carbon number ~ 6 alkyl or phenyl substituted with 2-20 carbon alkyl or benzyl, R ² represents unsubstituted or substituted with 1-6 carbon alkyl, phenyl or halogen atom substituted phenyl, Unsubstituted or substituted with more than one hydroxy group, a C 1-20 alkyl group, the alkyl group interrupted by more than one oxygen atom, unsubstituted or substituted with a C 1-6 alkyl group or phenyl group (Cycloalkyl having 5 to 8 carbons, unsubstituted or substituted with alkyl or phenyl having 1 to 6 carbons or alkyl having 2 to 20 carbons or benzyl)). For example, the application of the alkali-developable photocurable thermosetting resin composition according to item 2 of the patent application, wherein the urethane resin having a carboxyl group has an ethylenically unsaturated group. For example, the use of the alkali-developable photocurable thermosetting resin composition according to item 2 of the patent scope further includes a monomer having an ethylenically unsaturated group. For example, the use of the alkali-developable photocurable thermosetting resin composition according to item 2 of the patent scope, wherein the thermosetting component is a cyclic ether compound. A flexible printed wiring board manufactured by the method for manufacturing a flexible printed wiring board as described in claim 1, which has a patterned resin insulating layer, and the patterned resin insulating layer consists of It is composed of an urethane resin, a resin having a carboxyl group other than the urethane resin, a photobase generator, and an alkali-developable photocurable thermosetting resin composition of a thermosetting component.