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Tin Whisker User Group Updates Recommendations |
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Written by Chelsey Drysdale
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Friday, 15 December 2006 |
HERNDON, VA – iNEMI’s Tin Whisker User Group has revised “Recommendations on Lead-Free Finishes for Components Used in High-Reliability Products.”
It is the consensus of eight large manufacturers of high-reliability electronics assemblies that pure tin electroplating presents a risk in high-reliability applications. The guidelines are intended to minimize the risk of failures from tin whiskers and include information on issues such as corrosion, mechanical stress, use of tin over brass or tin over steel, thermal-cycled end use environments, and non-columnar grain structure. The group also makes formal recommendation regarding bright tin.
The User Group has changed its stance on annealing of matte tin over copper, saying it can be accepted when accompanied by supporting test data; updated its position on bias, noting recent data that indicates electrical bias is no longer considered a significant concern and does not require additional testing; changed information about alloy 42, warning that users should be cautious in using tin finishes on alloy 42 (Fe-42Ni) lead-frames in applications where there is significant thermal cycling; further clarified statements about the use of tin-bismuth finishes.
Revised recommendations can be downloaded at
http://thor.inemi.org/webdownload/projects/ese/tin_whiskers/Pb-Free_Finishes_v4.pdf.
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