Substrate and metallization selection for high power hybrid circuits based on thermal resistance and temperature cycling reliability

Thermal resistance literature for materials systems used in high-power hybrid modules is reviewed. Based on the review, beryllia appears to be the best choice for a ceramic substrate material followed by aluminium nitride. Thick-film metallization and other copper metallization systems for beryllia substrates have been evaluated for aged adhesion and temperature cycling reliability. Results indicate that beryllia substrates with directly bonded copper metallization present the best choice of materials system to address thermal resistance and thermal aging as well as temperature cycling reliability issues in the high-power hybrid circuits