Method of making drill back-up material for small bore drilling of circuit boards

摘要

Disclosed is an improved back-up sheet for backing a workpiece during a small bore drilling process. The sheet also possesses electrical properties making it an ideal candidate as a laminate (reinforcing layer or bonding sheet) in the construction of multi-layer printed wiring boards. The sheet or laminate comprises the cured residue of:P P(a) polyphenylene oxide;PP(b) a bisphenol A-type epoxy resin; andPP(c) an amine hardener for said epxoy resin, the weight ratio of a:b+c ranging from about 1:10 to 1:2.