Power module circuit board and a process for the manufacture thereof

摘要

A conductor pattern is formed on at least one surface of an AlN- or Si3N4- based ceramic substrate which is such that the ratio between the principal metal component binding with N to form the ceramic mass and the B in the BN remaining on the surface layer is no more than 50 X 10<-6> as either B/Al or B/Si ,wherein B/Al represents the ratio of IB to IAl where IB is the X-ray diffraction intensity of boron present on the surface layer and IAl is the X-ray diffraction intensity of aluminum, and B/Si represents the ratio of IB to ISi where IB is as defined above and ISi is the X-ray diffraction intensity of silicon. The thus produced circuit board has both a peel strength of at least 30 kg/mm<2> and a capability of withstanding at least 30 heat cycles and, hence, satisfies the performance requirements of the recent models of power module ceramic circuit boards.