Abstract

Electroless copper deposition solutions, and method of continuously electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, a non-formaldehyde copper reducing agent, such as hypophosphite, effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution, and a soluble source of non-copper metallic ions, such as nickel or cobalt ions, which act as an autocatalysis promoter to enable continuous plating using the solutions. The solutions are maintained in an alkaline condition and preferably in a pH range of 11-14 through the addition of pH adjusters. The properties of plating baths using the solutions, such as bath stability as well as plating process parameters such as plating rate, and the quality of deposit may be advantageously controlled through the appropriate selection of the non-copper metallic ion added and the complexing agent used. Optional additives, such as polymers, wetting agents, and various soluble unsaturated organic compounds, may also be utilized to influence these variables.