Influence of particulate Al_2O_3 addition on interfacial microstructure and electrical sheet resistance of thick film metallized aluminum nitride substrates

摘要

Submicrometer-sized Al_2O_3 powders were three-roll mixed with RuO_2-based resistor paste (Shoei R-2310) in varying weight ratios (5-20 wt./100), followed by thick-film printing the mixtures onto AIN substrates and fired over 850 deg.C in ambient air. Observation of the interfacial microstructure reveals that the addition of Al_2O_3 reduced the formation of interfacial pores pronouncedly; whilst, the film changed toward a porous structure as the powder loading approaches toward 20 wt./100. The electrical resistance of the film was found to increase exponentially with the Al_2O_3 fraction. A critical threshold for the resistance increase was at ～10 wt./100 of the Al_2O_3 fraction.