Test procedures needed for tin whisker failures

Greg Reed, Technical Editor -- Test & Measurement World, 9/1/2004

With the introduction and acceleration of lead-free materials for electronics systems, a re-emergence of tin whisker failures presents a problem for suppliers and users of electronics in high-reliability and harsh-environment applications. Tin whiskers are single crystals that sprout as a result of environmental factors, intermetallic formation, thermal expansion, compression during tin plating, and other issues. In electronic assemblies, they can produce short circuits, performance degradation, and, as debris, mechanical failures.

Electrically conductive tin whiskers can create field failures within systems that use pure tin coatings and finishes. Resulting electrical system failures pose serious reliability threats especially due to the industry reliance on commercial off-the-shelf tin-plated components. Amazingly, even after decades of research, there is no definitive set of testing guidelines to prevent spontaneous tin whisker growth.

One solution underway is the National Electronics Manufacturing Initiative's tin whisker user group proposal for acceptance-test requirements in high-reliability applications. This integrated approach to mitigating tin whisker failures intends to offer testing guidelines for suppliers and users of high-reliability products with design lives over five years. Check out their progress at www.nemi.org or contact chairman Joe Smetana at joseph.smetana@alcatel.com.

Contact Greg Reed at editor@aatr.net.