ALUMINUM NITRIDE - FROM THE POWDER TO THE SUBSTRATE

The aluminium nitride is a material which should replace alumina or be ryllia as substrate for power electronic applications. The powder, pre pared by carbothermal nitridation, is dispersed in a butanone-2-ethano l azeotrop solvent with a phosphate ester. Electrical conductivity, se dimentation, viscosity have been used to determine which phenomena tak e place in the defloculation of the suspension. The stability of AlN s uspensions is due mainly to an electrostatic mechanism, with a steric contribution. The aluminium nitride tape-casting slip has been sintere d at 1 850-degrees-C in a nitrogen atmosphere. Removing of the binder and plasticizer can be performed in the same oven at 650-degrees-C, du e to their nature and low concentration. The thermal conductivity of t he substrates has been measured and is in the 160 to 200 W/m.K range.