Low-resistance, solderable noble metal coatings - for piezoelectric or ferromagnetic ceramics using layers of gold with top layer of silver

摘要

The process of coating piezoelectric or ferromagnetic ceramics consists of the following steps: (a) application of the Au paste or prepn. to the ceramic; (b) firing at 500-600 degrees C.; (c) repetition of (a) and (b) until the requires surface resistance is obtd.; (d) application of a silver prepn. on the final gold layer to form a solderable top layer; (e) firing the Ag layer at 500-600 degrees C. The existing methods of vapour deposition or application of gold prepns. only gives a thin layer with the danger that Ag ions from the top coat of Ag may diffuse into the ceramic; ths danger is obviated by the present process.