Halogen-free dry film photosensitive resin composition
The present invention provides a halogen-free dry film photosensitive resin composition, which comprises (a) 10˜60 wt % of at least two kinds of acrylic resins having unsaturated carboxylic acid monomers as polymerized units; (b) 5˜20 wt % of a photosensitive resin having at least two (meth)acrylate groups; (c) 0.1˜15 wt % of a photoinitiator; and (d) 0.5˜20 wt % of a thermo-curing agent. The resin composition of the invention is suitable for use as a photoresist in the process of producing printed circuit boards. The resin composition of the invention is particularly suitable for use in the surface of printed circuit boards or semiconductor packages as a protective dry film solder mask.
1. A dry film photosensitive resin composition, comprising:
(a) 10˜60 wt % of a mixture of two different kinds of acrylic resins having an unsaturated carboxylic acid monomer as polymerized unit, wherein the average molecular weights of the two different kinds of acrylic resins are respectively between 15000 and 30000 and between 160000 and 220000;
(b) 5˜20 wt % of a photosensitive resin having at least two (meth)acrylate groups;
(c) 0.1˜15 wt % of a photoinitiator; and
(d) 0.5˜20 wt % of a thermo-curing agent.
2. The resin composition of claim 1 , wherein the acid values of the two different kinds of acrylic resins are respectively 180˜250 mg KOH/g and 150˜200 mg KOH/g.
3. The resin composition of claim 1 , wherein the unsaturated carboxylic acid monomer of component (a) is selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, 2-methacryloyloxyethyl succinate, 2-acryloyloxyethyl succinate, 2-methacryloyloxyethyl hexahydrophthalate, 2-acryloyloxyethyl hexahydrophthalate, 2-methacryloyloxyethyl phthalate, and 2-acryloyloxyethyl phthalate and a mixture thereof.
4. The resin composition of claim 1 , wherein the unsaturated carboxylic acid monomer of component (a) is acrylic acid or methacrylic acid, or a mixture thereof.
5. The resin composition of claim 1 , wherein the photosensitive resin of component (b) is selected from the group consisting of 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentylglycol di(meth)acrylate, polyethyleneglycol di(meth)acrylate, neopentylglycol adipate di(meth) acrylate, neopentylglycol di(meth)acrylate hydroxypivalate, dicyclopentadienyl di(meth)acrylate, caprolactone modified dicyclopentdienyl di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, trimethylol propane tri(meth)acrylate, dipentaerythriol tri(meth)acrylate, pentaerythriol tri(meth)acrylate, methyl trimethyl tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, dipentaerythriol penta(meth)acrylate, and dipentaerythriol hexa(meth)acrylate and a mixture thereof.
6. The resin composition of claim 1 , wherein the photoinitiator of component (c) is selected from the group consisting of benzoin, benzoin alkyl ether, benzil, ketals, acetophenone compounds, benzophenone, 4,4′-dimethyl-amino-benzophenone, thioxanthone compounds, and morpholino-propanone compounds, and a mixture thereof.
7. The resin composition of claim 1 , wherein the thermo-curing agent of component (d) is an anhydride or an epoxy resin.
8. The resin composition of claim 1 , which is characterized by a total halogen content of less than 200 ppm.
9. The resin composition of claim 1 , which is used as a solder mask on the surface of printed circuit boards or semiconductor packages.
10. The resin composition of claim 1 , which is used as a photoresist in the process of producing printed circuit boards.