MORPHOLOGY AND ADHESION STRENGTH IN ELECTROLESS CU METALLIZED ALN SUBSTRATE

The metallization of aluminum nitride substrates by electroless copper plating is investigated. The AIN substrate is etched by 4% NaOH to study the correlation between the adhesion strength and the surface roughness of etched AIN substrate. Both the as-received nonpolished and then polished AIN are employed herein. For the nonpolished substrate, the adhesion strength increases from 130 kg/cm2 for the sample with an average surface roughness of 0.2 mum to 230 kgf/cm2 for the one with an average surface roughness of 0.82 mum. For the polished substrate, the adhesion strength reaches 271 kg/cm2 with a surface roughness of 0.19 mum. Mechanical interlocking is the major cause for the adhesion strength between the Cu and AIN substrates. The polished substrate followed by etching could form fine cavities on the AIN surface, and the microetching effect results in a stronger mechanical interlocking, which increase the adhesion strength.