LOW-TEMPERATURE COFIRED AIN MULTILAYER SUBSTRATES

A process for low temperature co-fired AlN multilayer substrates is in troduced, Some key factors about this technology are delineated and di scussed. A two-step burnout process may solve the contradiction betwee n tungsten oxidation and carbon removal. Sintering with additives appe ars to improve densification at low temperature. DyN was found as a se cond phase in AlN ceramics, which suggests that Dy2O3 efficiently remo ves oxygen from the AlN lattice, The microstructure of AlN ceramics is ideal for achieving high thermal conductivity. Analysis of the AIN-W interface showed there were no second phases, but there was probably a n intricate interlocking structure between the grains of tungsten and AlN, Co-firing at 1650 degrees C for 4 h produced an AlN multilayer su bstrate with a thermal conductivity of up to 130 W m(-1) K-1.