Nee how Wee Mei, You do need to worry about this. The termination alloys 62Sn/36Pb/2Ag and 96Sn/4Ag will diffuse into the 63Sn/37Pb paste alloy forming new alloys near the interface regions. Depending on the time and temperature above Liquidus you will get more or less thorough mixing. You may get near the interface regions of 63Sn/37Pb/traceAg and 80Sn/19Pb/1Ag, repectively, with some dissolved base metal(s) as well gradiating towards the paste composition. Werner Engelmaier --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------