Kirk, The silver may dissolve in the molten solder unless it is protected by a barrier layer of copper or nickel. Typically the nickel is a better barrier than copper in equal thicknesses, but for normal soldering both will work well. The final tin or solder coating is to protect the copper or nickel from oxidation (passivation) and retain solderability. The intermetallic formation and copper or nickel dissolution during soldering is not an issue in this case where the dwell time is short. Phil Hinton ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################