Plastic lid material for use in semiconductor device packages and production process thereof

摘要

Disclosed herein are a plastic lid material for use in semiconductor device packages, which is low in specific gravity, excellent in moldability and cutting workability, and moreover superb in transparency, bond strength, heat resistance, dimensional stability and solvent resistance, and a production process thereof. The plastic lid material of the invention is composed of a crosslinked acrylic copolymer obtained by radical-polymerizing a monomer mixture which is composed of 100 parts by mass of a (meth)acrylic ester monomer component composed of a polyfunctional (meth)acrylic ester and a monofunctional (meth)acrylic ester, and 0-50 parts by mass of another monomer component copolymerizable with the (meth)acrylic ester monomer component, wherein the proportion of the polyfunctional (meth)acrylic ester is 10-90 mass% of the monomer mixture. The monomer mixture preferably contains a (meth)acrylic ester having at least one urethane linkage in a proportion of 20-80 mass%.