High power thick film circuitry on PECOS (porcelain enamel coating on steel) substrates

The need for high power density microcircuits has increased interest in the thermal and electrical characteristics of Porcelain Enamel Coatings on Steel (PECOS) for use as a substrate material. This high temperature substrate has been found to be compatible with most thick film inks which are presently available. The electrical and thermal characteristics are presented for a very compact line of low inductance sheet power resistors fabricated on the PECOS substrate and compared to similar power resistors fabricated on conventional alumina substrates. A two-dimensional finite volume heat transfer model has been developed for steady state power dissipation including convection and radiant energy transfer mechanisms. Computer analysis from the heat transfer model and predicted temperatures are compared to temperatures measured utilizing an infrared imaging system