The whiskering phenomenon has been a chronic problem plaguing the electronic industry for decades,especially with respect to pure tin coatings. With the advancements in tin bath chemistries and tin alloyplating with lead, this problem was surmounted to some extent. Recently, because of impending globalenvironmental regulations and legislation, the expedition to eliminate lead from electronic componentshas picked up momentum. Concerns of whisker formation in lead-free finishes have resurfaced andhave proved to be a nightmare to the electronic industry because of reliability and potential liabilityissues—especially in fine pitch applications. This paper addresses some of these concerns and attemptsto examine the process variables contributing to whisker formation, employing several proprietary leadfreechemistries on a plating line. In manufacturing operations, several factors such as substrate, itssurface preparation, micro-stresses in the deposits, nature of chemistry, and post-plating conditions wereexamined and their impact on whisker formation was evaluated. Applications in press-fit, plated-thruholes(PTH), and solder to board are also discussed in this paper.
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