David, Now that you have your connector handbook open could I ask if you would check to see if there is any information about the use of silver and tin as matting surfaces. I have a toggle switch that has a yellow brass movable contact with a silver button that contacts a tin plated copper button on the stationary side of the contact. Historically we avoid the use of gold and tin as matting surface because of the galvanic potential between the two materials and the possibility of fretting corrosion but I don't remember seeing any information concerning silver and tin Regards, George George M. Wenger, Andrew Corporation Reliability / FMA Engineer Base Station & Subsystems Group 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Wednesday, March 02, 2005 7:03 PM To: [log in to unmask] Subject: Re: [TN] Microcircuit Palladium Lead Finish (Good or Bad)? Hi folks! Wow, what a way to named - "the guy who cuts up his water pipes"! Well, its better than Doug's "It depends"! I do have some information that might be helpful - the following info is taken from Volume 4 Materials of the Connectors and Interconnections Handbook published by the Electronic Connector Study Group Inc. (sorry, no ISBN available) which is a really good resource on connector materials. - Pd wears better than Au for an equal plating thickness and can provide an adequate end of life contact - Pd is somewhat less galvanically active toward copper and nickel than corresponding deposits of either Au or rhodium - 60Pd40Ag is recognized as a good contact material for industrial and telecommunications applications - Pd can tarnish due to sulfur contributing sources - Pd can form frictional polymer in sliding contact applications that are exposed to organic vapors. The frictional polymer can increase contact resistance. I would recommend that you talk to the folks at Tyco or the J.M. Ney Company - a Pd finish is being used widely in electronics applications and you just need to confirm that your application/use environment is appropriate. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Charles Caswell <CharlesC@FESCORP .COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 02/28/2005 06:33 Re: [TN] Microcircuit Palladium AM Lead Finish (Good or Bad)? Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to Charles Caswell <CharlesC@FESCORP .COM> I don't have the spec available but I would think that Palladium finish in a gold socket would be fine. I would not want to solder directly to Palladium however. Maybe Dave ( the guy who cuts up water pipes from his house! ) could give us some insight. -----Original Message----- From: - Bogert [mailto:[log in to unmask]] Sent: Friday, 25 February 2005 5:06 PM To: [log in to unmask] Subject: [TN] Microcircuit Palladium Lead Finish (Good or Bad)? February 25, 2005 MIL-PRF-38535 microcircuit specification is confusing since in one section it identifies that to select a lead finish, include a suffix letter as part of the part number. The available suffix letters are Finish "A", "B", "C":, "D" and "X". "D" is for Palladium. "X" means either "A", "B", or "C" Finish However, Appendix A of the specification indicates that only lead Finishes "A" through "C" (or "X") are allowed. It appears that Finish "D", Palladium finished microcircuit leads are not allowed. Is this true? If so, why the apparent prohibition on Palladium lead finish? The question relates to selecting the lead finish for a microcircuit that is mounted in a socket having Gold-plated socket contacts. Normally, one should specify a Gold-plated microcircuit lead (Finish "C") to mate with the Gold-plated socket contact. However, from a galvanic corrosion standpoint, either Gold or Palladium should be ok. --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ------------------------------------------------------------------------------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. 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