Correct. The Gold plating is in direct contact with the Chromate over the AL. Most miltiary electronics are configured this way since they have little/no convection cooling- it's all through the chassis. I am begining to think the pictures I saw of the corrosion is just salt getting between...
Yea, this is the first time I have seen a failure like this. The chassis survived accept where the board attached to the chassis. I need to dig deeper. I am wondering if at some point they removed the coating for lower resistance for EMI reasons. I've never used zinc on aluminum, I will look...
We recently had an electronics box go through saltfog testing. It is a vented enclosure so during the test the corrosive atmosphere was present inside the box. There was significant corrosion where the board mounts to the aluminum chassis. The chassis is chromate, class 3 (low elec resistance)...
