JP6802799B2 - Curable resin composition, dry film and printed wiring board using it - Google Patents

Description

The present invention relates to a curable resin composition, a dry film, and a printed wiring board using the same.

The curable resin composition is widely used as a solder resist for printed wiring boards such as flexible printed wiring boards (hereinafter, abbreviated as FPC). This solder resist is used for the purpose of protecting the surface circuit of the printed wiring board, and insulation reliability is required. Particularly recently, the density of printed wiring boards has been remarkably increased, and some circuits have a minimum L (line) / S (space) of 10 μm / 10 μm, and higher insulation reliability than before is required. In particular, in FPC applications, since the electromagnetic wave shield is attached on an insulating film such as a coverlay, in addition to the ion migration resistance between circuits (XY axis directions), between the circuit via the solder resist and the electromagnetic wave shield. Ion migration resistance between layers (Z-axis direction) is also required, and higher insulation reliability, particularly ion migration resistance, is required.

On the other hand, conventionally, for example, as a means for improving the insulation reliability of a printed wiring board, particularly the ion migration resistance, a technique of blending a layered double hydroxide such as hydrotalcite with a photosensitive resin composition has been proposed ( Patent Document 1).

On the other hand, the solder resist is required to be flame-retardant because the printed wiring board is mounted on an electronic device. Among them, the solder resist for FPC is different from the solder resist for a rigid type printed wiring board formed on a glass epoxy board, and is usually formed on a polyimide substrate, so that higher flame retardancy is required.

JP-A-2010-237270

As described above, the curable resin composition used for the solder resist particularly for FPC applications is required to have excellent flame retardancy in addition to insulation reliability such as ion migration resistance, but at present, both of them are compatible. The reality was that it was difficult.
Therefore, an object of the present invention is a curable resin composition capable of obtaining a cured product having both insulation reliability such as ion migration resistance and flame retardancy, and a dry having a resin layer obtained from the composition. An object of the present invention is to provide a cured product of a film, the composition or a resin layer of the dry film, and a printed wiring board having the cured product.

As a result of diligent studies to solve the above problems, the present inventors have considered adding a hydrotalcite-based ion scavenger in order to improve insulation reliability, particularly ion migration resistance. It was noticed that the formulation of the ion scavenger of the system improves the insulation reliability such as ion migration resistance, but rather lowers the flame retardancy. Therefore, as a result of further studies, by using a mixture of hydrotalcite-based ion scavengers and non-hydrotalcite-based ion scavengers, ion migration resistance, etc., without unexpectedly reducing flame retardancy, etc. We have found that the insulation reliability of the above can be improved, and have completed the present invention.

That is, the curable resin composition of the present invention is a curable resin composition containing a carboxyl group-containing resin, a thermosetting component, a flame retardant and an ion scavenger, and the ion scavenger is a hydrotalcite-based ion. It is characterized by being a mixture of a scavenger and an ion scavenger other than a hydrotalcite type.

In the curable resin composition of the present invention, the blending ratio of the hydrotalcite-based ion scavenger and the non-hydrotalcite-based ion scavenger is preferably in the range of 100: 10 to 100: 500 on a mass basis. Is. In addition, the curable resin composition of the present invention preferably contains at least one of a photopolymerization initiator and a compound having an ethylenically unsaturated group. Further, the curable resin composition of the present invention is preferably a photosensitive resin composition containing a photopolymerization initiator. Furthermore, the thermosetting component is preferably a cyclic (thio) ether compound. Further, the curable resin composition of the present invention can be suitably used for forming at least one of a coverlay and a solder resist.

Further, the dry film of the present invention is characterized by having a resin layer obtained by applying and drying the curable resin composition on the film.

Further, the cured product of the present invention is characterized in that the curable resin composition or the resin layer of the dry film is cured.

Furthermore, the printed wiring board of the present invention is characterized by including the cured product.

According to the present invention, a curable resin composition capable of obtaining a cured product having both insulation reliability such as ion migration resistance and flame retardancy highly compatible, and a dry film having a resin layer obtained from the composition. , A cured product of the resin layer of the composition or the dry film, and a printed wiring board having the cured product can be provided.
The curable resin composition of the present invention can be suitably used for forming at least one of a coverlay and a solder resist of FPC. The curable resin composition of the present invention is also suitable as a resin composition for an adhesive layer of a coverlay having a multi-layer structure. Here, the adhesive layer refers to a resin layer of a coverlay having a laminated structure of two or more layers, which is in contact with the FPC.

It is a process drawing which shows typically an example of the manufacturing method of the printed wiring board suitable for this invention. It is a process diagram which shows typically another example of the manufacturing method of the printed wiring board suitable for this invention.

The curable resin composition of the present invention (hereinafter, also simply referred to as “resin composition”) contains a carboxyl group-containing resin, a thermosetting component, a flame retardant, and an ion scavenger. In particular, in the present invention, it is essential that the ion scavenger is a mixture of a hydrotalcite-based ion scavenger and a non-hydrotalsite-based ion scavenger, and by using these ion scavengers, Insulation reliability such as ion migration resistance and flame retardancy can be highly compatible.
Hereinafter, each component will be described in detail.

[Carboxylic group-containing resin]
As the carboxyl group-containing resin contained in the resin composition of the present invention, a known and commonly used resin compound containing a carboxyl group in the molecule can be used. The presence of the carboxyl group allows the resin composition to be alkaline developable. Further, from the viewpoint of making the resin composition of the present invention photocurable and developing resistance, it is preferable to have an ethylenically unsaturated bond in the molecule in addition to the carboxyl group, but the ethylenically unsaturated double bond is preferable. It is also possible to use only a carboxyl group-containing resin having no bond. When the carboxyl group-containing resin does not have an ethylenically unsaturated bond, a compound having one or more ethylenically unsaturated groups in the molecule (photopolymerizable compound) is used to make the composition photocurable. Need to be used together. The ethylenically unsaturated double bond is preferably derived from acrylic acid or methacrylic acid or a derivative thereof.

Specific examples of the carboxyl group-containing resin that can be used in the resin composition of the present invention include compounds (either oligomers and polymers) listed below.

(1) A carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth) acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth) acrylate, or isobutylene.

(2) Diisocyanate compounds such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates and aromatic diisocyanates, carboxyl group-containing dialcoic compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, polycarbonate-based polyols and polyethers. Carboxylic group-containing urethane resin by double addition reaction of diol compounds such as based polyols, polyester-based polyols, polyolefin-based polyols, acrylic polyols, bisphenol A-based alkylene oxide adduct diols, compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups. ..

(3) Aliphatic compounds such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates, and polycarbonate-based polyols, polyether-based polyols, polyester-based polyols, polyolefin-based polyols, acrylic-based polyols, and bisphenol A-based A terminal carboxyl group-containing urethane resin obtained by reacting an acid anhydride at the end of a urethane resin by a double addition reaction of a diol compound such as an alkylene oxide adduct diol, a compound having a phenolic hydroxyl group and an alcoholic hydroxyl group.

(4) Diisocyanate and bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, biphenol type epoxy resin ( Meta) A photosensitive carboxyl group-containing urethane resin obtained by a double addition reaction of an acrylate or a modified partial acid anhydride thereof, a carboxyl group-containing dialcohol compound and a diol compound.

(5) During the synthesis of the resin of (2) or (4) above, a compound having one hydroxyl group and one or more (meth) acryloyl groups is added to the molecule such as hydroxyalkyl (meth) acrylate, and the terminal (5) Meta) Acryloylated carboxyl group-containing urethane resin.

(6) During the synthesis of the resin according to (2) or (4) above, one isocyanate group and one or more (meth) acryloyl groups are added to the molecule, such as a molar reaction product such as isophorone diisocyanate and pentaerythritol triacrylate. A carboxyl group-containing urethane resin that has been acrylicized at the end (meth) by adding the compound.

(7) A photosensitive carboxyl group-containing resin obtained by reacting a bifunctional or higher polyfunctional (solid) epoxy resin with (meth) acrylic acid and adding a dibasic acid anhydride to a hydroxyl group existing in a side chain.

(8) Photosensitivity in which (meth) acrylic acid is reacted with a polyfunctional epoxy resin obtained by further epoxidizing the hydroxyl groups of a bifunctional (solid) epoxy resin with epichlorohydrin, and a dibasic acid anhydride is added to the generated hydroxyl groups. Sexual carboxyl group-containing resin.

(9) A carboxyl group-containing polyester resin obtained by reacting a polyfunctional oxetane resin with a dicarboxylic acid and adding a dibasic acid anhydride to the generated primary hydroxyl group.

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

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

(12) The resins (1) to (11) above further have one epoxy group and one or more (meth) acryloyl groups in the molecule such as glycidyl (meth) acrylate and α-methylglycidyl (meth) acrylate. A photosensitive carboxyl group-containing resin to which a compound is added.

In addition, in this specification, (meth) acrylate is a generic term for acrylate, methacrylate and a mixture thereof, and the same applies to other similar expressions.

Since the above-mentioned carboxyl group-containing resin has a large number of carboxyl groups in the side chain of the backbone polymer, it can be developed with an alkaline aqueous solution.
The acid value of the carboxyl group-containing resin is preferably in the range of 20 to 200 mgKOH / g, more preferably in the range of 40 to 150 mgKOH / g. When the acid value of the carboxyl group-containing resin is within the above range, the alkali solubility is good and patterning by alkaline development becomes easy.

The weight average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is preferably 1,000 to 100,000, more preferably 3,000 to 50,000. When the molecular weight is within the above range, the alkali solubility is good, and patterning by alkaline development becomes easy.

[Thermosetting component]
The thermosetting component has a functional group capable of an addition reaction with a carboxyl group by heat. As the thermosetting component, for example, a compound having a cyclic (thio) ether group is preferable, and an epoxy resin, a polyfunctional oxetane compound and the like can be mentioned.

The epoxy resin is a resin having an epoxy group, and any known epoxy resin can be used. Examples thereof include a bifunctional epoxy resin having two epoxy groups in the molecule, a polyfunctional epoxy resin having many epoxy groups in the molecule, and the like. The epoxy resin may be hydrogenated.

Specifically, bisphenol A type epoxy resin, brominated epoxy resin, novolak type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidylamine type epoxy resin, hidden in type epoxy resin, alicyclic epoxy. Resin, trihydroxyphenylmethane type epoxy resin, bixilenol type or biphenol type epoxy resin or a mixture thereof; bisphenol S type epoxy resin, bisphenol A novolac type epoxy resin, tetraphenylol ethane type epoxy resin, heterocyclic epoxy resin, Diglycidyl phthalate resin, tetraglycidyl xylenoyl ethane resin, naphthalene group-containing epoxy resin, epoxy resin having dicyclopentadiene skeleton, glycidyl methacrylate copolymer epoxy resin, cyclohexyl maleimide and glycidyl methacrylate copolymer epoxy resin, CTBN Examples include modified epoxy resins.

As the heat-curable component, known and commonly used compounds such as maleimide compound, blocked isocyanate compound, amino resin, benzoxazine resin, carbodiimide resin, cyclocarbonate compound, and episulfide resin may be blended.

One type of such a thermosetting component may be used alone, or two or more types may be used in combination. As the blending amount of the thermosetting component, it is preferable that the equivalent ratio with the above-mentioned carboxyl group-containing resin (carboxyl group: thermoreactive group such as epoxy group) is 1: 0.1 to 1:10. By setting the compounding ratio in such a range, the development becomes good and a fine pattern can be easily formed. The equivalent ratio is more preferably 1: 0.2 to 1: 5.

[Flame retardants]
As the flame retardant constituting the resin composition of the present invention, a known and commonly used flame retardant can be used. Flame retardants include phosphoric acid esters and condensed phosphoric acid esters, phosphorus element-containing (meth) acrylates, phosphorus-containing compounds having phenolic hydroxyl groups, cyclic phosphazene compounds, phosphazenic oligomers, phosphorus-containing compounds such as phosphinic acid metal salts, and trioxide. Examples thereof include antimony compounds such as antimony and antimony pentoxide, halides such as pentabromodiphenyl ether and octabromodiphenyl ether, and layered compound hydroxides such as metal hydroxides such as aluminum hydroxide and magnesium hydroxide. One type of the flame retardant may be used alone, or two or more types may be used in combination.

式中、Ｍ^２＋は２価の金属陽イオン、Ｍ^３＋は３価の金属陽イオン、Ａ^ｎ−はｎ価の陰イオンを表し、各元素および原子団の下付き添字は各元素および原子団の比率を表し、Ｘは０＜Ｘ≦０．３３である。ｍはｍ≧０であるが、脱水により大きく変わる。 [Ion scavenger]
The ion scavenger contained in the resin composition of the present invention is a mixture of a hydrotalcite-based ion scavenger and a non-hydrotalcite-based ion scavenger.
Hydrotalcite and hydrotalcite-like compounds can be preferably used as the hydrotalcite-based ion scavenger contained in the resin composition of the present invention. Hydrotalcite and hydrotalcite-like compounds are, for example, a positively charged basic layer [Mg _1-X Al _X (OH) ₂ ] ^{X +} and a negatively charged intermediate layer [(CO ₃ ) _{X / 2} · mH _2). O] A layered inorganic compound composed of ^X- . Many divalent and trivalent metals have a layered structure similar to this, and the general structural formula is represented by the following formula (I).

Wherein, M ²⁺ is a divalent metal cation, M ³⁺ is a trivalent metal cation, A ^n-represents an n-valent anion, subscripts of the elements and atomic groups are the elements and atomic groups Represents the ratio of, and X is 0 <X ≦ 0.33. Although m is m ≧ 0 , it changes greatly due to dehydration.

Specific examples of hydrotalcite and hydrotalcite-like compounds include Indigirite Mg ₂ Al ₂ [(CO ₃ ) ₄ (OH) ₂ ], 15H ₂ O, Fe ₂ ⁺ ₄ Al ₂ [(OH) ₁₂ CO ₃ ]. 3H ₂ O, Quintinite Mg ₄ Al ₂ (OH) ₁₂ CO ₃ · H ₂ O, Manasseite Mg ₆ Al ₂ [(OH) ₁₆ CO ₃ ] · 4H ₂ O, SjOegrenite Mg ₆ Fe ^{3 +} ₂ [(OH) ₁₆ CO _{3] · 4H 2 O, Zaccagnaite} Zn 4 Al 2 (CO 3) (OH) 12 · 3H 2 O, Desautelsite Mg 6 Mn 3+ 2 [(OH) 16 CO 3] · 4H 2 O, hydrotalcite Mg 6 Al 2 [ (OH) ₁₆ CO ₃ ] · 4H ₂ O, Pyroaurite Mg ₆ Fe ^{3 +} ₂ [(OH) ₁₆ CO ₃ ] · 4H ₂ O, Reevesite Ni ₆ Fe ^{3 +} ₂ [(OH) ₁₆ CO ₃ ] · 4H ₂ O, Examples thereof include Stichtite Mg ₆ Cr ₂ [(OH) ₁₆ CO ₃ ] · 4H ₂ O, Takovite Ni ₆ Al ₂ [(OH) ₁₆ CO ₃ ] · 4H ₂ O, and the like.

Commercially available products include Kyowa Chemical Industry Co., Ltd .; Alchemizer, DHT-4A, Kyoward 500, Kyoward 1000, and Sakai Chemical Co., Ltd. STABIACE series HT-1, HT-7, HT-P. Synthetic hydrotalcite-like compounds such as.
One of these hydrotalcite-based ion scavengers may be used alone, or two or more thereof may be used in combination.

As the ion scavenger other than the hydrotalcite type contained in the resin composition of the present invention, a known and commonly used ion scavenger can be used. As the ion scavenger other than the hydrotalcite type, any of cation exchange type, anion exchange type, and both ion exchange type can be used.
Specific examples thereof include inorganic particles made of Zr-based compounds, inorganic particles made of Sb-based compounds, and inorganic particles made of Bi-based compounds. Further, inorganic particles composed of a binary system of Sb-based compound and Bi-based compound, inorganic particles composed of a binary system of Mg-based compound and Al-based compound, and inorganic particles composed of a binary system of Zr-based compound and Bi-based compound. Examples thereof include inorganic particles composed of a ternary system of a Zr-based compound, an Mg-based compound, and an Al-based compound. Among them, from the viewpoint of not reducing the effect of the flame retardant, inorganic particles composed of Zr-based compounds, inorganic particles composed of binary systems of Zr-based compounds and Bi-based compounds, and ternary of Zr-based compounds, Mg-based compounds and Al-based compounds. Inorganic particles composed of systems are preferred.
Examples of commercially available products of the hydrotalcite other than the ion capturing捉agent, manufactured by Toagosei (Inc.), IXE-100, IXE- 300, IXE-500, IXE-550, IXE-800, IXE-600, IXE -6107, IXE-6136, IXEPLAS-A1, IXEPLAS-B1 and the like can be mentioned.
As these ion scavengers other than the hydrotalcite type, one type may be used alone, or two or more types may be used in combination.

In the present invention, it is essential that the ion scavenger is a mixture of a hydrotalcite-based ion scavenger and a non-hydrotalcite-based ion scavenger. By using these ion scavengers, insulation reliability such as ion migration resistance and flame retardancy can be highly compatible. This is considered to be due to the following reasons. When a hydrotalcite-based ion scavenger is added to improve insulation reliability, especially ion migration resistance, the flame retardancy is reduced, but the amount of hydrotalcite-based hydrotalcite is not reduced. When an ion scavenger is added, the ion migration resistance becomes insufficient. Therefore, it is considered that the insufficient ion migration resistance can be compensated for while maintaining the flame retardancy by using an ion scavenger other than the hydrotalcite type having flame retardancy in combination. Therefore, according to the present invention, it has become possible to achieve both insulation reliability, particularly ion migration resistance and flame retardancy.
The blending ratio of the hydrotalcite-based ion scavenger and the non-hydrotalcite-based ion scavenger is in the range of 100: 10 to 100: 500, preferably in the range of 100: 50 to 100: 400 on a mass basis. , More preferably in the range of 100: 100 to 100: 400. The total amount of the ion scavenger is 1 to 50% by mass, preferably 2 to 40% by mass, and more preferably 2 to 20% by mass with respect to the entire resin composition in terms of solid content.

The resin composition of the present invention can further contain at least one of a photopolymerization initiator and a compound having an ethylenically unsaturated group.

(Photopolymerization initiator)
As the photopolymerization initiator, known and commonly used ones can be used, and examples thereof include benzoin compounds, acylphosphine oxide compounds, acetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, and thioxanthone compounds.
In particular, when used in the PEB step after light irradiation, which will be described later, a photopolymerization initiator also having a function as a photobase generator is suitable. In this PEB step, a photopolymerization initiator and a photobase generator may be used in combination.

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

The α-aminoacetophenone compound may have a benzoin ether bond in the molecule, and when irradiated with light, cleavage occurs in the molecule to produce a basic substance (amine) that acts as a curing catalyst. Specific examples of the α-aminoacetophenone compound include (4-morpholinobenzoyl) -1-benzyl-1-dimethylaminopropane (trade name: Irgacure 369, manufactured by BASF Japan) and 4- (methylthiobenzoyl) -1-methyl. -1-morpholinoetan (trade name: Irgacure 907, manufactured by BASF Japan), 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl]- A commercially available compound such as 1-butanone (trade name: Irgacure 379, manufactured by BASF Japan) or a solution thereof can be used.

As the oxime ester compound, any compound that produces a basic substance by light irradiation can be used. Examples of the oxime ester compound include CGI-325 manufactured by BASF Japan, Irgacure OXE01, Irgacure OXE02, N-1919 and NCI-831 manufactured by Adeka Corporation as commercially available products. Further, the compound described in Japanese Patent No. 4,344,400, which has two oxime ester groups in the molecule, can also be preferably used.

As such a photopolymerization initiator, one type may be used alone, or two or more types may be used in combination. The blending amount of the photopolymerization initiator in the resin composition is 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin in terms of solid content. When it is in the range of 0.1 to 30 parts by mass, the curing balance between the coating film surface and the deep part is improved, and the sensitivity, resolution and the like can be improved. In addition, the photocurability is improved, and the coating film characteristics such as insulation reliability and chemical resistance can be improved. However, when used as a resin composition for an adhesive layer of a coverlay having a two-layer structure, a structure that does not contain a photopolymerization initiator is preferable.

(Compound with ethylenically unsaturated group)
A compound having an ethylenically unsaturated group (hereinafter, also referred to as a photopolymerizable compound) is a compound having one or more ethylenically unsaturated groups in the molecule. The photopolymerizable compound assists the polymerization reaction of the ethylenically unsaturated group by irradiation with active energy rays. The ethylenically unsaturated group is preferably derived from (meth) acrylate.

Examples of the photopolymerizable compound include commonly known polyester (meth) acrylates, polyether (meth) acrylates, urethane (meth) acrylates, carbonate (meth) acrylates, and epoxy (meth) acrylates. Specifically, 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; N, N-dimethylacrylamide. , N-methylol acrylamide, acrylamides such as N, N-dimethylaminopropyl acrylamide; aminoalkyl acrylates such as N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropyl acrylate; hexanediol, trimetyl propane, Polyhydric alcohols such as pentaerythritol, dipentaerythritol, tris-hydroxyethyl isocyanurate or polyfunctional acrylates such as their ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts; phenoxyacrylates, bisphenol A di. Polyfunctional acrylates such as acrylates and ethylene oxide adducts or propylene oxide adducts of these phenols; glycidyl ethers such as glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate. Polyfunctional acrylates; not limited to the above, acrylates and melamine acrylates obtained by directly acrylated polyols such as polyether polyols, polycarbonate diols, hydroxyl group-terminated polybutadienes, and polyester polyols, or urethane acrylates via diisocyanates, and the acrylates. At least one of each methacrylate corresponding to the above can be mentioned.

Further, an epoxy acrylate resin obtained by reacting a polyfunctional epoxy resin such as a cresol novolac type epoxy resin with acrylic acid may be used as a photopolymerizable compound. Such an epoxy acrylate-based resin can improve the photocurability without lowering the dryness to the touch.

The blending amount of the above photopolymerizable compound is 1 to 50 parts by mass, more preferably 3 to 30 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin in terms of solid content. When the blending amount is in the range of 1 to 50 parts by mass, the photocurability and tackiness can be improved.

(Polymer resin)
In the resin composition of the present invention, a commonly known polymer resin can be blended for the purpose of improving the flexibility and dryness to the touch of the obtained cured product. Examples of the polymer resin include cellulose-based, polyester-based, phenoxy-resin-based polymers, polyvinyl acetal-based, polyvinyl butyral-based, polyamide-based, polyamide-imide-based binder polymers, block copolymers, and elastomers. One type of the polymer resin may be used alone, or two or more types may be used in combination.

(Inorganic filler)
An inorganic filler can be added to the resin composition of the present invention. Inorganic fillers are used to suppress curing shrinkage of cured products of resin compositions and improve properties such as adhesion and hardness. Examples of the inorganic filler include barium sulfate, amorphous silica, molten silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, Neuburg and the like. Can be mentioned. One type of the above-mentioned inorganic filler may be used alone, or two or more types may be used in combination.

(Colorant)
A colorant can be added to the resin composition of the present invention. As the colorant, commonly known colorants such as red, blue, green, yellow, white, and black can be used, and any of pigments, dyes, and pigments may be used.

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

(Other optional ingredients)
If necessary, the resin composition of the present invention may further contain components such as a mercapto compound, an adhesion accelerator, an antioxidant, and an ultraviolet absorber. As these, those known in the field of electronic materials can be used. In addition, the above resin compositions include known and commonly used thickeners such as fine silica, organic bentonite, and montmorillonite, defoaming agents such as silicone-based, fluorine-based, and polymer-based, and / or leveling agents, and silane coupling agents. , Known and commonly used additives such as rust preventives and the like can be blended.

[Dry film]
The dry film of the present invention has a resin layer made of the resin composition of the present invention. It may be a dry film having a multi-layer structure having a layer made of a resin composition other than the resin composition of the present invention.
In making a dry film, for example, the resin composition of the present invention is diluted with an organic solvent to adjust the viscosity to an appropriate level, and the resin composition is applied onto a carrier film to a uniform thickness by a known method such as a comma coater. Then, 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 is used. The thickness of the carrier film is not particularly limited, but is generally selected as appropriate in the range of 10 to 150 μm. After forming the resin layer on the carrier film, a peelable cover film may be further laminated on the surface of the resin layer.

The resin composition or dry film of the present invention as described above can be used for a resin insulating layer of a printed wiring board, for example, a coverlay or a solder resist. The resin composition of the present invention can also be used as a resin composition for an adhesive layer, which is a resin layer in contact with a printed wiring board of a coverlay having a laminated structure of two or more layers.

The coverlay (laminated structure) having a laminated structure of two or more layers includes an adhesive layer which is a resin layer in contact with a printed wiring board and a protective layer which is a resin layer which can be patterned by light irradiation of the upper layer. It is preferably composed of. By using the resin composition of the present invention as the adhesive layer of this laminated structure, a laminated structure such as a coverlay composed of an adhesive layer and a protective layer can collectively form a pattern by development. Insulation reliability such as ion migration resistance and flame retardancy can be highly compatible.

Here, the resin composition constituting the protective layer contains a carboxyl group-containing resin (alkali-soluble resin), a photopolymerization initiator, and a thermosetting component, and is described in JP-A-2015-155199. The above-mentioned compositions and the like can be used. As the carboxyl group-containing resin (alkali-soluble resin), a carboxyl group-containing resin (alkali-soluble resin) having an imide ring or an imide precursor skeleton is preferable.

[Manufacturing method of printed wiring board]
Next, an example of a method for producing a printed wiring board from the resin composition of the present invention will be described with reference to the process diagrams of FIGS. 1 and 2. Although FIGS. 1 and 2 show a case where the resin layer has a laminated structure, it may be a case where only one layer is formed.

The method for manufacturing the printed wiring board shown in the process diagram of FIG. 1 is a step of forming a layer of a laminated structure on a printed wiring board on which a conductor circuit is formed (lamination step), and an active energy ray is applied to the layer of the laminated structure. This is a manufacturing method including a step of irradiating in a pattern (exposure step) and a step of subjecting the layers of the laminated structure to alkaline development to collectively form layers of the patterned laminated structure (development step). Further, if necessary, after alkaline development, further photo-curing or thermosetting (post-cure step) is performed to completely cure the layer of the laminated structure, and a highly reliable printed wiring board can be obtained.

The method of manufacturing the printed wiring board shown in the process diagram of FIG. 2 is a step of forming a layer of a laminated structure on a printed wiring board on which a conductor circuit is formed (lamination step), and an active energy ray is applied to the layer of the laminated structure. A step of irradiating in a pattern (exposure step), a step of heating a layer of this laminated structure (a step of heating (Post Exposure Baker; PEB)), and an alkaline development of the layer of the laminated structure to make a pattern. It is a manufacturing method including a step (development step) of forming a layer of a laminated structure. Further, if necessary, after alkaline development, further photo-curing or thermosetting (post-cure step) is performed to completely cure the layer of the laminated structure, and a highly reliable printed wiring board can be obtained. In particular, when an imide ring-containing alkali-soluble resin is used in the resin layer 4 (protective layer), it is preferable to use the procedure shown in the process diagram of FIG.

Hereinafter, each step shown in FIG. 1 or 2 will be described in detail.
[Laminating process]
In this step, the printed wiring board 1 on which the conductor circuit 2 is formed is provided with a resin layer 3 (adhesive layer) made of a resin composition and a resin layer 4 (protective layer) made of a resin composition on the resin layer 3. , To form a laminated structure. Here, each resin layer constituting the laminated structure forms the resin layers 3 and 4 by, for example, sequentially applying and drying the resin composition constituting the resin layers 3 and 4 to the printed wiring board 1. Alternatively, the resin composition constituting the resin layers 3 and 4 may be formed in the form of a dry film having a two-layer structure by laminating on the printed wiring board 1.
This resin layer is preferably made of an alkali-developed photosensitive resin composition. As the alkali-developable photosensitive resin composition, a known resin composition can be used, and for example, a known resin composition for coverlay or solder resist can be used. By forming the resin layer into a laminated structure instead of one layer in this way, a cured product having further excellent impact resistance and flexibility can be obtained.

The method for applying the resin composition to the wiring board may be a known method such as a blade coater, a lip coater, a comma coater, or a film coater. In addition, the drying method uses a hot air circulation type drying furnace, IR furnace, hot plate, convection oven, etc. equipped with a heat source of the heating method using steam, and the hot air in the dryer is brought into countercurrent contact, and is supported by the nozzle. A known method such as a method of spraying on the body may be used.
In the case of the laminating method, first, the resin composition is diluted with an organic solvent to adjust the viscosity to an appropriate level, applied on a carrier film, and dried to prepare a dry film having a resin layer. Next, a known method of peeling off the carrier film after the resin layer is bonded so as to be in contact with the wiring board by a laminator or the like can be mentioned.

[Exposure process]
In this step, the photopolymerization initiator contained in the resin layer 4 is activated in a negative pattern by irradiation with active energy rays, and the exposed portion is cured. As the exposure machine, a direct drawing device, an exposure machine equipped with a metal halide lamp, or the like can be used. The mask for patterned exposure is a negative type mask.

As the active energy ray used for exposure, it is preferable to use laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm. By setting the maximum wavelength in this range, the photopolymerization initiator can be activated efficiently. The exposure amount varies depending on the film thickness and the like, but is usually 100 to 1500 mJ / cm ² .

[PEB process]
In this step, after the exposure, the exposed portion is cured by heating the resin layer. By this step, a photopolymerization initiator having a function as a photobase generator is used, or a base generated in the exposure step of the resin layer 4 composed of a composition in which the photopolymerization initiator and the photobase generator are used in combination is used. The resin layer can be cured to a deep part. 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 resin composition in the present invention is, for example, a ring-opening reaction of the epoxy resin by a thermal reaction, strain and curing shrinkage can be suppressed as compared with the case where curing proceeds by a photoradical reaction.

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

[Post-cure process]
In this step, after the developing step, the resin layer is completely thermoset to obtain a highly reliable coating film. The heating temperature is, for example, 140 ° C to 180 ° C. The heating time is, for example, 20 to 120 minutes. In addition, light may be applied before or after post-cure.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples and Comparative Examples. In the following, "part" and "%" are all based on mass unless otherwise specified.

(Examples 1 to 14, Comparative Examples 1 to 6)
<Preparation of resin composition>
The materials described in Examples and Comparative Examples were blended according to the formulations shown in Tables 1 to 3 below, premixed with a stirrer, and kneaded with a three-roll mill to prepare a curable resin composition. The values in the table are parts by mass unless otherwise specified.

The prepared curable resin composition was evaluated for insulation reliability and flame retardancy. The evaluation contents are as follows.
<Insulation reliability>
A polyimide substrate having a copper thickness of 18 μm (Espanex manufactured by Nippon Steel Chemical Co., Ltd.) having a pattern of L / S = 50/50 μm was surface-treated using MEC Bright CB-801Y. The curable resin compositions of Examples 1 to 14 and Comparative Examples 1 to 6 were applied to the entire surface of the polyimide substrate by screen printing, dried at 80 ° C. for 30 minutes, and allowed to cool to room temperature. The obtained substrate was exposed to the entire surface with an exposure amount of 300 mJ / cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and 30 ° C. and a spray pressure of 0 using a 1 mass% Na ₂ CO ₃ aqueous solution. The development process was carried out for 60 seconds under the condition of .2 MPa. After heat-curing this substrate at 150 ° C. for 60 minutes, an electromagnetic wave shielding material was press-bonded to prepare an evaluation substrate for insulation reliability.
A bias voltage of DC50V is applied to the produced evaluation substrate in the Z-axis direction, and the resistance value is continuously measured in a constant temperature and humidity chamber at 85 ° C. and 85% RH to confirm the presence or absence of a short circuit. Was evaluated. The judgment criteria are as follows.
◯: No short circuit occurred after 1000 hours.
X: A short circuit occurred within 1000 hours.

<Flame retardant>
The curable resin compositions of Examples 1 to 14 and Comparative Examples 1 to 6 were applied to a polyimide film base material having a thickness of 50 μm and a thickness of 25 μm (200H, 100H manufactured by Toray DuPont Co., Ltd.) over the entire surface by screen printing. It was dried at 80 ° C. for 15 minutes and allowed to cool to room temperature. The back surface was also coated on the entire surface and dried at 80 ° C. for 20 minutes. The obtained double-sided coated substrate was exposed on both sides at an exposure amount of 300 mJ / cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and a 1 mass% Na ₂ CO ₃ aqueous solution was used. The development process was carried out for 60 seconds under the conditions of 30 ° C. and a spray pressure of 2 kg / cm ² . This double-sided coating substrate was heat-cured at 150 ° C. for 60 minutes to prepare a flame-retardant evaluation substrate.
The produced evaluation substrate was subjected to a thin vertical combustion test conforming to the UL94 standard to evaluate its flame retardancy. Based on the UL94 standard, the evaluation criteria were marked with 〇 for those whose flame retardancy was confirmed and x for those without flame retardancy.

＊１：カルボキシル基含有変性エポキシアクリレート樹脂、不揮発分６５．０質量％、固形分酸価１００ｍｇＫＯＨ／ｇ（日本化薬（株）製）
＊２：ビフェニルノボラック型エポキシ樹脂（日本化薬（株）製）
＊３：フェノキシホスファゼン（大塚化学（株）製）
＊４：ホスフィン酸金属塩（クラリアント社製）
＊５：オキシムエステル系光重合開始剤（ＢＡＳＦジャパン社製）
＊６：ハイドロタルサイト化合物（協和化学工業（株）製）
＊７：無機イオン捕捉剤（両イオン交換型）（東亜合成（株）製）
＊８：無機イオン捕捉剤（両イオン交換型）（東亜合成（株）製）
＊９：無機イオン捕捉剤（陽イオン交換型）（東亜合成（株）製）
＊１０：無機イオン捕捉剤（両イオン交換型）（東亜合成（株）製）
＊１１：ビスフェノールＡ−ＥＯ変性ジアクリレート（新中村化学工業（株）製）

* 1: Carboxyl group-containing modified epoxy acrylate resin, non-volatile content 65.0% by mass, solid content acid value 100 mgKOH / g (manufactured by Nippon Kayaku Co., Ltd.)
* 2: Biphenyl novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.)
* 3: Phenoxyphosphazene (manufactured by Otsuka Chemical Co., Ltd.)
* 4: Metal phosphinic acid salt (manufactured by Clariant)
* 5: Oxime ester-based photopolymerization initiator (manufactured by BASF Japan Ltd.)
* 6: Hydrotalcite compound (manufactured by Kyowa Chemical Industry Co., Ltd.)
* 7: inorganic ion capturing捉agent (both ion exchange type) (manufactured by Toagosei Co., Ltd.)
* 8: inorganic ion capturing捉agent (both ion exchange type) (manufactured by Toagosei Co., Ltd.)
* 9: inorganic ion capturing捉agent (cation-exchange type) (manufactured by Toagosei Co., Ltd.)
* 10: inorganic ion capturing捉agent (both ion exchange type) (manufactured by Toagosei Co., Ltd.)
* 11: Bisphenol A-EO modified diacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd.)

As is clear from the results shown in Tables 1 to 3, in Examples 1 to 14, a hydrotalcite-based ion scavenger and a non-hydrotalcite-based ion scavenger are used in combination, and insulation reliability and flame retardancy are used. Both sexes were good. On the other hand, in Comparative Examples 1 and 2, the insulation reliability was lowered because the ion scavenger was not contained. Further, in Comparative Example 3, only a hydrotalcite-based ion scavenger was used, and although insulation reliability was obtained, flame retardancy was lowered. Furthermore, in Comparative Examples 4 to 6, only an ion scavenger other than the hydrotalcite type was used, and the insulation reliability was lowered. As a result, in these comparative examples, insulation reliability and flame retardancy could not be highly compatible.

(Examples 15 and 16, Comparative Examples 7 and 8)
<Formation of laminated structure>
(Synthesis Example 1: Synthesis example of an alkali-soluble resin having an imide ring)
12.2 g of 3,5-diaminobenzoic acid in a separable three-necked flask equipped with a stirrer, nitrogen introduction tube, fractional ring and cooling ring, 2,2'-bis [4- (4-aminophenoxy) Phenyl] 8.2 g of propane, 30 g of NMP, 30 g of γ-butyrolactone, 27.9 g of 4,4′-oxydiphthalic anhydride, 3.8 g of trimellitic anhydride were added, and the temperature was 100 rpm under a nitrogen atmosphere. Was stirred for 4 hours. Next, 20 g of toluene was added, and the mixture was stirred for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 ° C. and 150 rpm to obtain an imide ring-containing alkali-soluble resin solution. Then, γ-butyrolactone was added so that the solid content was 30% by mass. The obtained resin solution had a solid acid value of 86 mgKOH / g and Mw10000.

<Adjustment of resin composition constituting each layer>
According to the formulation shown in Table 4 below, the materials described in Examples and Comparative Examples are blended, premixed with a stirrer, and then kneaded with a three-roll mill to form an adhesive layer and a protective layer. The thing was prepared. The values in the table are parts by mass unless otherwise specified.
The resin compositions for the adhesive layer of the laminated structures of Examples 15 and 16 and Comparative Examples 7 and 8 are each of Examples 2 and 3 and Comparative Examples 3 and 6 except that they do not contain a photopolymerization initiator. It was used as the same composition as the resin composition.

<Formation of adhesive layer>
A flexible printed wiring board on which a circuit having a copper thickness of 18 μm was formed was prepared, and pretreatment was performed using CZ-8100 manufactured by MEC. Then, the resin composition for each adhesive layer was applied to the pretreated flexible printed wiring board so that the film thickness after drying was 25 μm. Then, it was dried in a hot air circulation type drying oven at 90 ° C./30 minutes to form an adhesive layer made of a resin composition.

<Formation of protective layer>
The resin composition for each protective layer was applied onto the adhesive layer so that the film thickness after drying was 10 μm. Then, it was dried at 90 ° C./30 minutes in a hot air circulation type drying oven to form a protective layer made of a resin composition.

In this way, an uncured laminated structure composed of the adhesive layer and the protective layer described in Examples 15 and 16 and Comparative Examples 7 and 8 was formed on the flexible printed wiring board.

<Manufacturing of flexible printed wiring board>
For the uncured laminated structure on each flexible printed wiring board on which the uncured laminated structure was formed as described above, first, an exposure device (HMW-680-GW20) equipped with a metal halide lamp was used to 500 mJ / cm ² Fully exposed with. Then, after performing a PEB step at 90 ° C. for 30 minutes, development (30 ° C., 0.2 MPa, 1 mass% Na ₂ CO ₃ aqueous solution) is performed in 60 seconds, and thermosetting is performed at 150 ° C. × 60 minutes. A flexible printed wiring board having a cured laminated structure was obtained.

<Insulation reliability>
An electromagnetic wave shielding material was press-bonded to each of the flexible printed wiring boards obtained above to prepare an evaluation substrate for insulation reliability.
A bias voltage of DC50V is applied to the produced evaluation substrate in the Z-axis direction, and the resistance value is continuously measured in a constant temperature and humidity chamber at 85 ° C. and 85% RH to confirm the presence or absence of a short circuit. Was evaluated. The judgment criteria are as follows.
◯: No short circuit occurred after 1000 hours.
X: A short circuit occurred within 1000 hours.

<Flame retardant>
Each of the flexible printed wiring boards obtained above was subjected to a thin vertical combustion test conforming to the UL94 standard, and the flame retardancy was evaluated. Based on the UL94 standard, the evaluation criteria were marked with 〇 for those whose flame retardancy was confirmed and x for those without flame retardancy.

<Flexibility (MIT test)>
A MIT test (R = 0.38 mm / using a base material of Upirex 12.5 μm manufactured by Ube Industries, Ltd.) was carried out on each of the flexible printed wiring boards obtained above, and the flexibility was evaluated. The case where it is bent for 120 cycles or more is marked with ◯, and in this case, the flexibility as a flexible wiring board can be satisfied. When it was less than 120 cycles, it was evaluated as x.

The results obtained are shown in Table 4 below.

＊１２：合成例１のポリイミド樹脂
＊１３：ビスフェノールＡ型エポキシ樹脂（分子量９００）（三菱化学（株）製）
＊１４：ビスフェノールＡ型エポキシ樹脂，エポキシ当量１９０，質量平均分子量３８０（三菱化学（株）製）

* 12: Polyimide resin of Synthesis Example 1 * 13: Bisphenol A type epoxy resin (molecular weight 900) (manufactured by Mitsubishi Chemical Corporation)
* 14: Bisphenol A type epoxy resin, epoxy equivalent 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)

As is clear from the results shown in Table 4, in Examples 15 and 16, a hydrotalcite-based ion scavenger and a non-hydrotalcite-based ion scavenger are used in combination in the resin composition for the adhesive layer. The flexible printed wiring board having the laminated structure formed by using this has good insulation reliability and flame retardancy, and also has good flexibility. On the other hand, in Comparative Example 7, only a hydrotalcite-based ion scavenger is used in the resin composition for the adhesive layer, and the flexible printed wiring board having a laminated structure formed by using the hydrotalcite-based ion scavenger has insulation reliability. Has been obtained, but the flame retardancy has decreased. Further, in Comparative Example 8, only an ion scavenger other than the hydrotalcite type is used in the resin composition for the adhesive layer, and the flexible printed wiring board having a laminated structure formed by using the ion scavenger is insulated and reliable. The sex has decreased. As a result, in these comparative examples, it was not possible to achieve both insulation reliability and flame retardancy of the flexible printed wiring board.

1 Printed circuit board 2 Conductor circuit 3 Resin layer (adhesive layer)
4 Resin layer (protective layer)
5 mask

Claims (8)

A curable resin composition containing a carboxyl group-containing resin, a thermosetting component, a flame retardant, and an ion scavenger.
It contains two phosphorus-containing compounds as the flame retardant and contains
The ion scavenger consists of a mixture of a hydrotalcite-based ion scavenger and a non-hydrotalcite-based ion scavenger, and the total amount of the mixture is 1 in terms of solid content with respect to the entire resin composition. ~ 50% by mass,
Curing for printed wiring boards , characterized in that the blending ratio of the hydrotalcite-based ion scavenger and the non-hydrotalcite-based ion scavenger is in the range of 100: 10 to 100: 500 on a mass basis. Sex resin composition. The curable resin composition according to claim 1, further comprising at least one of a photopolymerization initiator and a compound having an ethylenically unsaturated group. The curable resin composition according to claim 1, which is a photosensitive resin composition containing a photopolymerization initiator. The curable resin composition according to claim 1, wherein the thermosetting component is a cyclic (thio) ether compound. The curable resin composition according to claim 1, which is used to form at least one of a coverlay and a solder resist. A dry film characterized by having a resin layer obtained by applying and drying the curable resin composition according to claim 1 on the film. A cured resin composition according to claim 1, or a cured product obtained by curing the resin layer of the dry film according to claim 6. A printed wiring board comprising the cured product according to claim 7.

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