Abstract
Extraneous deposition phenomenon of electroless copper plating is investigated. It is confirmed that this phenomenon is caused by formation of cuporous oxide or decreasing dissolved oxygen in the bath. Extraneous deposition occurs extensively under 1 ppm of dissolved oxygen. Also the viscosity and specific gravity of the plating bath increased by accumulation of formate ion from main reaction and side reaction is also accelarated the extraneous deposition. Cause factors of these phenomena were analyzed by measuring of evolved hydrogen volume and anodic polarization curve. It was concluded that extraneous deposition occurs by disproportionation reaction of cuporous ion or reduction power of nascent state hydrogen.
