PREPARATION OF ALUMINA CERAMIC SURFACES FOR ELECTROLESS AND ELECTROCHEMICAL METAL DEPOSITION

摘要

The invention relates to the metal coating of 96 % alumina ceramic substrates through the use of aqueous solutions. To achieve better bonding characteristics of the metal coat to the ceramic, said ceramic surface is cleansed, before and after the removal of vitreous material by etching, with a mixture of sulfuric acid and hydrogen peroxide, heated to about 100 degrees Celsius. The metallic coat comprises several layers sequentially deposited on the ceramic surface, the first one being an electroless nickel-boron or nickel-phosphorus layer, overlaid by electroplated layers of different metals to give low resistance, good solderability and protection against oxidation. Between the electroless deposition step and the following electroplating steps, the substrates are treated with ultrasound to eliminate flakes on the electrolessly deposited surface, improving the fabrication of narrow printed circuit lines less than 50 microns wide.