Elemental carbon has been identified as the dark material that has "developed" on the surface of a pin at the point where it makes electrical contact with a socket. The applied voltage in one case is 12 VDC and in another it is 5 VDC. It is suspected that the high vibration environment in which the device operates is causing intermittent opening of the contact area and electrical arcing is causing the carbon deposition. I believe I have seen literature which identifies atmospheric C0_2 as the primary source of the carbon (possibly some CO also). Can anyone refer me to literature which confirms, disconfirms or otherwise provides enlightenment on the precise nature of this process? Thanks --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------