Effects of thiourea and Guanidine Hydrochloride on electroless copper plating

The effects of thiourea nd guanidine hydrochloride on electroless copper plating were studied by voltammetric and gravimetric methods. Thiourea stabilizes the plating bath and simultaneously decreases the plating rate. The effect of stabilization is attributed to the strong complexing ability of thiourea with Cu(I) and the surface adsorption of thiourea on copper. The surface adsorption is the main reason for the decrease in plating rate. In the case of guanidine hydrochlo-ride, the plating rate is maximum when its concentration is approximately 5 mg/liter. The occurrence of the maximum is interpreted in terms of the interplay of the delocalized ~- electron effect of guanidine hydrochloride and its surface ad-sorption on copper. Since ABS was plated with metals successfully in 1960 (1), the technology of plastics plating has been improving continuously (2, 3). Numerous parts for industrial and household products formerly made with metals were re-placed by plated plastics (4-6). The demand for plated plastics has been increasing rapidly; hence, the technique of preparing more stable electro]ess plating baths wit