Copper pyrophosphate/PY61H plating bath: Control of ammonia

Methods of ammonia anaysis are analyzed, and the requirements for control of ammonia in copper pyrophosphate/PY61H plating baths are identified. Printed wiring boards plated in copper pyrophasphate/Py61H baths are utilized in numerous programs. Standard bath solutions of the same ammonia concentration but varying concentrations of copper, pyrophosphate, and brightener (PY61H) were analyzed by three methods: Kjeldahl distillation/titration, hexamethylene tetramine titration, and the ammonia gas-sensing electrode. All three analytical techniques demonstrated the independence of ammonia concentration with changing bath composition. Standard deviations of +-0.003 N, +-0.025 N, and +-0.005 N, respectively, were observed.