Is it time to breathe a sigh of relief regarding the fear of tin whiskers in non-lead components? The IPC – or the Association Connecting the Electronics Industries –
releaseda paper in early July entitled, “Final Report – Round Robin Testing and Analysis of Lead Free Solder Pastes with Alloys of Tin, Silver and Copper,” (http://www.ipc.org/contentpage.asp?Pageid=184.108.40.206).
The paper lists three versions of a tin/silver/copper alloy that are being widely used as a replacement for tin-with-lead finishes. The paper also reveals the combination of tin, silver and copper that IPC deems the most successful for mitigating the growth of tin whiskers. From the paper, you can get the impression that the issue of tin whiskers has been tidied up and effectively solved.
The one comparison IPC didn’t include was the tin/silver/copper alloy tested against the traditional tin/lead. Is that meaningful? A great number of engineers in the defense and aerospace industries have loudly expressed concerns that tin whiskers will cause planes to fall out of the sky and life-supporting medical equipment to short out. Does that tin/silver/copper alloy put that fear to rest?