PURPOSE: To increase heat conductivity and glass transition temperature and improve heat radiation and insulation at a high temperature and electrical reliability by using bisphenol A-type epoxy resin of high purity which is refined at a purity of 90% or more through moleculer distillation.
CONSTITUTION: An insulation layer 2 made of insulating is formed on a base metal plate 1 and further, clad in conductive foil 3 made of copper foil or composite foil, and then, a conductive circuit is formed by etching and a ceramic chip part 5, a semiconductor device 6 and a terminal 7, etc., are mounted on the circuit. As the layer 2, an insulating material made up by hardening an insulating composition composed of bisphenol A-type epoxy resin of high purity and an inorganic filler is used. That is, as insulating material, a material which is produced by hardening a mixture made up of bisphenol A-type epoxy resin of 90% purity or more and inorganic filler, having heat conductivity of 5.0×10-3-18.0×10-3 (cal/°C.cm.sec) and also having glass transition temperature of 164-240°C is used. It is thereby possible to improve heat radiation property, insulation at a high temperature, etc.
NAKANO TATSUO
KATO KAZUO
