THE EFFECT OF GOLD-NICKEL METALLIZATION MICROSTRUCTURE ON FLUXLESS SOLDERING

Gold plating is used in the microelectronics industry to maintain the wettability of metal substrates. The nature of wetting during solderin g of gold plated metals is discussed, and the results of experiments o n the fluxless wettability and oxidation of gold plated nickel are des cribed. The results suggest that electrodeposition of a thin gold plat e (0.14 mum) and the concurrent reduction of nickel oxide produce a go ld-nickel system which will wet without flux. Oxidation of nickel was observed to occur via nickel out-diffusion and by direct exposure of t he substrate through pinhole plating defects. Auger chemical analysis indicates that pinholes do not produce oxidation of the surrounding su bstrate area.