Suitable cleaning agent for gold switch contacts

[Bannerman]

We are struggling to find a suitable cleaning agent for Gold flashed contacts used in our electronic switches for a particular application.

We currently are using 99.7% pure Ethanol which seems to be causing problems during tempreture/humidity cycling (85% RH) of the switching unit during life tests. Small dark patches appear on the gold contact pill surface.

My suspicions are around the lack of purity in the Ethanol i.e. there are traces of Water, Methanol & Iso-propanol.
Has anyone got any idea what we may be seeing and how we could solve it?

 

[IRstuff]

What is the substrate?

TTFN

 

[Bannerman]

The gold flash is 0.15u thick on >2u of Ni.
The main material is CU (0.1mm)

 

[kenvlach]

It's not the gold corroding. Probably either porosity in the gold flash or some contact roughness wearing away the gold. Not sure of your application, but for typical contacts, the minimum gold electroplating is at least 20 micro-inch (0.8 microns), about 3x as thick as the decorative flash of 0.15 microns mentioned.
So maybe, the ethanol is providing an accelerated corrosion test that may save you from parts failures months later, out in customers parts.

I'm not sure of the testing conditions, but you cannot expect ethanol to not absorb water in high humidity.

Consider palladium plating instead of gold.

 

[IRstuff]

Maybe there's some arcing that's vaporizing the gold.

TTFN

 

[nbucska]

Rhodium is harder

Plesae read FAQ240-1032
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http://geocities.com/nbucska/>