Microstructure and plating thickness analysis of different surface finished plated printed circuit boards

Abstract

Different surface finished lead-free electroplated Cu substrates were prepared using an electrolytic process jointly developed for special applications. The surface morphology and plated layer thicknesses were investigated using atomic force microscope (AFM) and seanning electron microscope (SEM). From SEM micrographs, it was confirmed that the plated layers i.e., Au/Ni and Ag/Ni were well deposited on Cu substrates uniformly. In addition, the plated layer thicknesses were increased with an increasing processing temperature. The average Au/Ni p lated layers thicknesses atplated temperatures of30°C, 40°C and 5 0°C were about 0.67μm, 0.71μm and 0.77 μm, respectively. On the other hand, the average Ag/Ni plated layers thicknesses at plated temperatures of 10°C, 20°C and 30°C were about 6.5μm, 7.7μm and 8.4μm, respectively. From AFM observations, it was confirmed that the plated layer appeared to have a very smooth surface without any defects such as cra cks, delamination etc., confirming the successful application of the specially developed electrolytic process.