Development of a bath for codeposition of copper and platinum

To improve the mechanical properties of electrodeposited copper, a new bath was developed for the codeposition of copper and platinum. A pyrophosphate bath employing chloroplatinic acid as a source of platinum was investigated at current densities ranging from 1 to 4 A dm-2 and temperatures from 20 to 60 deg C. Bright, shiny and crack-free deposits were obtained at low current densities (i.e., 1-2 A dm-2). The amount of platinum observed in the deposits was found to increase with the current density and bath temperature. The Knoop hardness was found to increase with platinum content in the deposits. Corrosion rates measured in solutions of NaCl were found to decrease with platinum content. Deposits containing up to 3.9 wt % of platinum can be obtained by electrodeposition. As compared to electrodeposited copper from the acid bath, the Cu-Pt deposits exhibited a 17% increase in Knoop hardness and a 21 % increase in corrosion resistance.