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 [log in to unmask] ______________________________ 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] ------