Heat-curable composition, dry film, and printed wiring board
An object of the present invention is to provide: a heat-curable composition capable of yielding a cured article in which crack generation during a heating-cooling cycle can be inhibited; a dry film thereof; and a printed wiring board comprising the cured article. The heat-curable composition is characterized by comprising a semisolid or a solid epoxy compound and a curing accelerator that is made miscible with the epoxy compound when heated at 130 to 220° C. The dry film comprises a resin layer formed from this heat-curable composition, and the printed wiring board comprises a cured article obtained from the heat-curable composition or the dry film.
1. A dry film, comprising:
a resin layer formed from a heat-curable composition,
wherein the heat-curable composition includes
an epoxy compound which is semisolid or solid,
a solvent, and
a curing accelerator that is made miscible with the epoxy compound when heated at a temperature in a range of from 130 to 220° C. and
the resin layer includes the solvent in an amount of 0.1 to 4% by weight based on a total weight of the resin layer including the solvent.
2. The dry film according to claim 1 , wherein the solvent includes toluene and cyclohexanone.
3. The dry film according to claim 1 , wherein the curing accelerator is at least one of an imidazole compound and a phosphonium salt.
4. A method for producing a printed wiring board, comprising:
curing the resin layer of the dry film according to claim 1 .
5. The dry film according to claim 1 , wherein the resin layer includes the solvent in an amount of 0.3 to 3% by weight based on the total weight of the resin layer including the solvent.
6. A printed wiring board, comprising:
a cured article obtained by a process comprising curing the resin layer of the dry film according to claim 1 .
7. A printed wiring board, comprising:
a cured article obtained by a process comprising curing the resin layer of the dry film according to claim 2 .
8. A printed wiring board, comprising:
a cured article obtained by a process comprising curing the resin layer of the dry film according to claim 3 .
9. The dry film according to claim 1 , wherein the epoxy compound is semisolid.
10. The dry film according to claim 1 , wherein the epoxy compound is solid.
11. The dry film according to claim 1 , wherein the epoxy compound comprises a semisolid epoxy compound and a solid epoxy compound, and is included in a total amount of 10 to 35% by weight based on a total amount of the heat-curable composition.
12. A printed wiring board, comprising:
a cured article obtained by a process comprising curing the resin layer of the dry film according to claim 11 .
13. The dry film according to claim 1 , wherein the curing accelerator that is made miscible with the epoxy compound when heated at a temperature in a range of from 150 to 200° C.
14. The dry film according to claim 2 , wherein the solvent is at least one selected from the group consisting of isobutyl alcohol, toluene, methyl isobutyl ketone, n-butanol, butyl acetate, 2-methoxypropanol, isobutyl acetate, tetrachloroethylene, ethylene glycol monomethyl ether, methyl butyl ketone, isopentyl alcohol, ethylene glycol monoethyl ether, N,N-dimethylformamide, ethylene glycol monoethyl ether acetate, turpentine oil, cyclohexanone, and ethylene glycol monobutyl ether.
15. The dry film according to claim 2 , wherein the solvent comprises at least one of toluene and cyclohexanone.
16. The dry film according to claim 15 , wherein the curing accelerator comprises at least one of tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide and hexadecyltributyl phosphonium chloride.
17. The dry film according to claim 15 , wherein the curing accelerator comprises 2-phenyl-4,5-dihydroxymethylimidazole.
18. The dry film according to claim 16 , wherein the curing accelerator is included in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of a total amount of the epoxy compound which is semisolid or solid in the heat-curable composition.
19. The dry film according to claim 17 , wherein the curing accelerator is included in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of a total amount of the epoxy compound which is semisolid or solid in the heat-curable composition.
20. The dry film according to claim 11 , wherein the curing accelerator is included in an amount of 0.01 to 5 parts by weight with respect to 100 parts by weight of a total amount of the epoxy compound which is semisolid or solid in the heat-curable composition.