Hello Dave, Thanks for the info. on solder joint contamination issues in your recent message. With regard to the Zn and Co contamination issue, in both cases these elements were present in the plated deposit of SMT connectors which had been solder paste reflowed onto the board (one connector had Zn present in the deposit; another sample had Co present in the deposit). Problems were reported, and it was theorized that perhaps the Zn and the Co had dissolved from the plated coating into the solder joint. Rob Schetty LeaRonal Inc. ---------- From: David D Hillman Sent: Thursday, October 30, 1997 7:00 AM To: [log in to unmask] Subject: Re: Assembly (Sn-Pb Solder Joint Contamination) Hi Rob - Zn and Co solder joint contamination? Wow, what was the substrate that you were soldering? It is pretty hard to get Zn to stay in the solder joint unless you are specifically using a solder that contains Zn. The Zn tends to "dross out" of a solder alloy. I am still looking for any Co info that might be available. The maximum % P that a solder alloy can have is one of those confusing questions - both JSTD-001 and JSTD-006 (except for ultra pure alloys, paragraph 3.2.4) are silent on %P allowed. Several solder alloy manufacturers use P additions to solder alloys for a number of proprietary reasons - typical claims are that P makes solder more fluid, stronger solder joints, reduces drossing of solder pots, etc. I know several people using solder alloys that contain P and they are quite satisfied with the results. I haven't worked with any of the P containing solder alloys so I can't substantiate the improvement claims either true or false. Hope that helps. Dave Hillman Rockwell Collins [log in to unmask] [log in to unmask] on 10/27/97 10:08:36 AM To: [log in to unmask] cc: [log in to unmask], [log in to unmask], David D Hillman/CedarRapids/Collins/Rockwell Subject: Re: Assembly (Sn-Pb Solder Joint Contamination) Thanks Alexander, Charles, and Dave for recent responses to my inquiry about the max. % Zn and Co in Sn-Pb solder joints and industry specs. related to same. With regard to your specific questions: Charles - I'm located at LeaRonal's world headquarters in Freeport, NY, USA. Dave - Yes, in two separate instances, Zn and Co may have been present unintentionally in the surface finish and thereby are suspected to have contaminated the solder joint. ==> I have one more question for Technet - what about the maximum % P allowable in a Sn-Pb solder joint? Thanks. 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 ##############################################################