Hi Steve, My comment has nothing to do with Ag-containing solders, but with the effect of Ag-plating on component leads. Immersion Ag may be thin enough not to give you the necessary Ag concentration. The experience I referred to goes back to about 1982. The industry found out—and since forgot except for a few old-timers like me—what silver can do to solder joints, when TI moved some of its PLCC production to Singapore. There somebody decided to Ag-plate the leads. At the first unfortunate recipient of this product, IBM-Austin, the PLCCs started to literally fall off the PCBs when slight bending, such during fixturing for functional testing, put even very small loads onto the solder joints. As a consequence of this scary news (nobody knew about the Ag yet and compliant leads were just invented and without history), 17 competing companies joined forces and formed the IEEE Compliant Lead Task Force. Silver, it turns out creates an even weaker intermetallic compound (IMC) with tin than does gold. The necessary IMC concentration necessary for this effect is about the same as for Au. Because of legal problems (the 2 companies with the lowest PLCC fatigue lives threatened to sue everybody involved in the IEEE CLTF), the results, except for some preliminary data, were never published. If you go back into the TechNet archives, you will find some problems related to Ag (plating) being discussed. Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 904-437-8747, Fax: 904-437-8737 E-mail: [log in to unmask], Website: www.engelmaier.com ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################