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July 2014 • SMT Magazine 53 TIN WHISKER RISK MANAGEMENT By CoNFoRMAl CoATING continues fEATURE materials used on the coupons that were not bent for both base metals (Table 4). In addition, there was no indication of tenting of the con- formal coat where a tin whisker may push the coating away from the tin plating. There were tin whiskers or odd-shaped eruptions observed beneath the conformal coating for samples of both base metals and all coating types; howev- er the observed tin whiskers did not cause any disturbance to the conformal coating. The pres- ence of conformal coating over the tin whis- kers was confirmed by EDS. Figure 7 includes a scanning electron micrograph detailing the interface of the parylene coating to the uncoat- ed region of one coupon. Tin whiskers are ob- served growing on the uncoated region of the coupon; however the parylene coating appears undisturbed. figure 6: Scanning electron micrographs detailing the appearance of tin whiskers growing on uncoated regions of the bright tin-plated coupons. figure 7: Scanning electron micrograph (600X magnification) detailing the appearance tin whiskers growing on an uncoated region of a coupon adjacent to the parylene coating.