An Investigation into Methods for Minimising Tin Whisker Growth

摘要

Previous work has shown that pure tin and tin alloy plating processes do not produce coatingswith the same resistance to whiskering as tin/lead alloy electrodeposits. In the earlier study nickelbarrier layers, deposit annealing and thick coatings were all shown to be beneficial in reducingwhiskering.A pure tin deposit which possesses specific X-ray diffraction patterns (i.e. the absence of smallangles between adjacent crystal planes) has also been shown to have minimum whisker formationtendencies.This paper presents the results of further laboratory trials examining the effect of depositthickness of a new tin deposit on whiskering. The influence of pre-treatment (etch depth, etchrate and etch type), post treatment annealing (time/temperature) and the use of undercoats (nickeland copper) are reported.Recommendations for minimising whisker formation are presented.