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Date: | Tue, 30 Apr 96 08:44:14 cst |
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Hello Terry:
We have had one experience similar to yours which may help shed
some light on your header problem. We had a gold/nickel over copper
base metal connector that built up resistance over time on a program.
Scanning electron analysis showed only the presence of nickel and gold
so we ruled out the possibility of copper diffusing through the nickel
(which should be very unlikely anyway!). After careful examination of
the SEM photo's we notice several "protrusions" in some of the porous
areas in the gold plating. Using Auger analysis we found that the gold
was porous enough that the nickel had diffused it's way to the
surface. We worked with the connector vendor on the quality of the
gold plating and the problem was resolved. I rarely see any
information on nickel diffusing to the surface of gold plating and I
wouldn't expect it to but then nothing is absolute. Good luck.
Dave Hillman
Rockwell Collins
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______________________________ Reply Separator _________________________________
Subject: DES> Connector Reliability
Author: [log in to unmask] at ccmgw1
Date: 4/29/96 12:37 PM
We have a header in a prototype system with brass sprung contacts with gold
plate over nickel, contacting pins which are also gold-plate over nickel.
This connector carries 3A, and is showing a strong tendency to increase in
contact resistance in field tests (up to 150 mOhm). Removing and refitting
the connector takes the contact resistance back to "as new" (<40 m Ohm).. The
connectors have been examined by a test lab and pronounced OK, with no
contamination. No deposit or oxidation is visible on the surface.
Has anyone seen similar failure mechanism? What's the physics?
Terry Davey -------------------------------- [log in to unmask] ------
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