Hi Rob - I went digging through my files and found a reference made by Klein Wassink that recommended the Zinc level be limited to less than 0.005% due to it causing drossing, grittiness, and grain boundary weakening (ok, solder colony weakening for those who don't like the words grain boundary and solder in the same sentence). I couldn't find anything on Cobalt, I don't have a Sn-Co phase diagram and the Pb-Co phase diagram shows that lead and cobalt don't like each other at all. Hope this helps. Did you have a suspected contamination issue? Dave Hillman Rockwell Collins [log in to unmask] [log in to unmask] on 10/20/97 10:56:31 AM Please respond to [log in to unmask]; Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: David D Hillman/CedarRapids/Collins/Rockwell) Subject: [TECHNET] Assembly Hi Technet, Does anyone have information regarding the maximum percentage of cobalt and zinc that are permissible in a Sn-Pb solder joint? Thanks in advance for any answers. Rob Schetty LeaRonal Inc. ############################################################## 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 ############################################################## ############################################################## 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 ##############################################################