Influence of perchloric acid on the kinetics of immersion plating of copper onto aluminium

The effect of perchloric acid on the kinetics of immersion plating of copper onto aluminium from a bath containing complexing agent over a range of concentration of copper (0.382¯2.55 g dm-3) and perchloric acid (0.255¯0.590 g dm-3), and at temperatures from 28°C to 50°C has been investigated. The perchloric acid effectively breaks down the impervious film from the aluminium surface and allows the copper to be deposited on it. The rate process also is found to be improved by incorporating perchloric acid in the solution. The mixed potential measured during the immersion process in the complex bath was compared with the mixed potential obtained from the superimposition of the partial anodic and cathodic partial polarization curves. The mixed potentials are found to be close to each other. The deposit structure is found to be more crystalline and compact when the perchloric acid concentration was increased above 0.344 g dm-3. The effect of temperature during immersion plating of copper onto aluminium has been investigated and the results are in good agreement with those reported by previous workers.