PREPARATION AND SINTERING OF ALUMINUM NITRIDE SUITABLE FOR ELECTRONIC SUBSTRATE PURPOSES

Aluminum nitride powders intended for the preparation of substrates of high thermal conductivity and electrical resistivity have been synthesized by direct nitridation of such alloys of aluminum as Al/Sr, Al/Ca and Al/Mg, with the concentration of the alloying element as low as 1 wt.%. Compacts of aluminum nitride powders derived from the nitridation of the alloys have been pressureless sintered with the aid of a sintering additive to densities and thermal diffusivities as high as 99% theoretical and 0.74 cm2 s-1 respectively. The study indicates that, of the various alloying elements considered, Sr is best and leads to highly desired properties for the sintered AlN bodies. Specifically, pressureless sintering of compacts of the Al/Sr derived AlN powder in the presence of Y2O3 has been shown to result in a thermal conductivity of 175 W m-1 K-1 and an electrical resistivity of 5 x 10(13) OMEGA cm for the sintered body.