METHOD OF CONSISTENTLY PRODUCING A COPPER DEPOSIT ON A SUBSTRATE BY ELECTROLESS DEPOSITION WHICH DEPOSIT IS ESSENTIALLY FREE OF FISSURES

摘要

ABSTRACT OF THE DISCLOSUREElectroless metal plating solutions are formulatedand controlled to provide high quality metal depositsby establishing the intrinsic cathodic reaction rate ofthe solution less than 110% of the intrinsic anodicreaction rate. Electroless copper plating solutions con-taining plating rate accelerators containing delocalizedpi bonds and having the concentration of the reducingager no greater than 1.2 times the concentration oft copper ion can deposit copper on printed wiring?ards of quality sufficient to pass a thermal stressof 10 seconds contact with molten solder at 288 °Cwithout cracking the copper deposits on the surface ofthe printed wiring boards or in the holes. As theplating solution ages by build up of plating reactionby-products or by-products and contamination, thequality of the copper deposited can be maintained byincreasing the copper ion concentration and pH of thesolution, while reducing or maintaining substantiallyconstant the concentration of the reducing agent.