Someone asked about the material composition: The pins are tin plated and the socket contacts are gold plated. There is no evidence of corrosion or galvanic action here. A laboratory used a SEM to determine the presence of carbon and FTIR to rule out the presence of any significant quantities of carbon containing compounds--none was detected. Another common sense point: electrical arcing between two metal conductors with the production of a "carbon appearing" deposit at the point where the arcing occurs is a phenomenon with which most people are familiar. I would like to understand the process better--including the source of the carbon. Searching through physics, chemistry, electronics, failure analysis and other literature has failed to give me a clue. If someone has a clue as to where I can find some relevant literature on this subject I am very interested in hearing from you. Thanks again. > -----Original Message----- > From: TechNet [SMTP:[log in to unmask]] On Behalf Of Dehoyos, Ramon > Sent: Friday, March 26, 2004 7:59 AM > To: [log in to unmask] > Subject: Re: [TN] Carbon Buildup On Tin Plated Contacts > > That is very true most of the sockets are reliable. If there is > any defect such as the fingers of the sockets not putting enough pressure > on the inserted pin or the fingers not properly secured ( loose, > fingers of the sockets are inserted into the socket housing ) or fingers > fall down and collapsed when a pin is inserted, then there will be arcing > and carbon build up. > Regards, > Ramon > > > -----Original Message----- > > From: Crepeau, Phil (Space Technology) > > Sent: Thursday, March 25, 2004 8:16 PM > > To: [log in to unmask] > > Subject: Re: [TN] Carbon Buildup On Tin Plated Contacts > > > > hi, > > > > i know what you all are talking about. nevertheless i just want to say > that many mil spec digital, power, and rf mil spec connectors have gold > pins and sockets and they are extremely reliable. > > > > phil > > > > -----Original Message----- > > From: David Douthit [mailto:[log in to unmask]] > > Sent: Thursday, March 25, 2004 4:35 PM > > To: [log in to unmask] > > Subject: Re: [TN] Carbon Buildup On Tin Plated Contacts > > > > > > Bogert, > > > > Based on this, we are prohibiting use of sockets for new design > equipment. Most military equipment prohibits use of sockets (ref > historical MIL-STD-2000). In my opinion, no equipment that is intended > for long term reliability should ever use sockets. > > > > I agree. Even gold to gold contacts can become intermittent due to > deposition of > > particles and reactive gases combined with micro vibration and or > thermal excursions. > > > > David A. Douthit > > Manager > > LoCan LLC > > > > > > > > - Bogert wrote: > > > > >What is the material finish of the socket contacts? Is it the same as > the part pins? If not, you could have corrosion issue due to different > finishes. For example tin plated pins inserted into socket with gold > plated contacts could be problem. Another problem could be spread socket > contacts that cause poor electrical connections resulting in arcing and > subsequent carbon deposits. Unfortunately we have used numerous sockets > in fielded equipment with significant quality issues. Based on this, we > are prohibiting use of sockets for new design equipment. Most military > equipment prohibits use of sockets (ref historical MIL-STD-2000). In my > opinion, no equipment that is intended for long term reliability should > ever use sockets. > > > ----- Original Message ----- > > > From: Chafin, Ken G.<mailto:[log in to unmask]> To: > [log in to unmask]<mailto:[log in to unmask]> Sent: Wednesday, March 24, 2004 > 5:10 PM > > > Subject: [TN] Carbon Buildup On Tin Plated Contacts > > > > > > > > > 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]<mailto:[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]<mailto:[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]<mailto:[log in to unmask]>: SET Technet Digest > > > Search the archives of previous posts at: > http://listserv.ipc.org/archives<http://listserv.ipc.org/archives>> > > > Please visit IPC web site > http://www.ipc.org/contentpage.asp?Pageid=4.3.16<http://www.ipc.org/conten > 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