Acoustic Emission During Nickel Electroplating of Copper

The possibility of correlating acoustic emission responses during electroplating of Ni on Cu, with the effects of internal stresses on plating quality was investigated. Nickel plating was carried out with a high p H Watts bath varying current density between 0.3-5.0 A/dm exp 2 and operating temp. between ambient temp. and 60 deg C. Test duration varied between 20-90 min yielding deposit thicknesses between 1-25 mu m. Low current density/ambient temp. deposits and high current density/high temp. deposits were characterized by high quality and absence of acoustic emission activity. High current density/ambient temp. deposits exhibited a very poor surface quality and an early and conspicuous acoustic emission activity. Deposits obtained at low current density /ambient temp. in a bath containing a tensioning agent, displayed a good quality at visual examination but exhibited nevertheless a certain acoustic emission activity. Acoustic emission detection appears capable of monitoring the onset of damage mechanisms due to internal stresses during electroplating. 5 ref.--AA