Thermal head with heat-resistant insulating coating material.

摘要

A thermal head has a metallic substrate (1) on which is formed an insulating layer (2). A plurality of heat generating resistors (4) are formed on the insulating layer and are connected to electrodes (6,7). The insulating layer is formed from an aromatic polyimide resin produced by dehydration cyclization of biphenyl tetracarboxylic acid anhydride and an aromatic diamine. The resin has a thermal decomposition onset at more than 500C, a thermal expansion coefficient of 4.5 x 10<-><5> cm/cm/C or less and a thermal shrinkage of 2% or less.