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
>
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