# Gold percentage in connectors



## SapunovDmitry (Jan 25, 2008)

Hi,everyone.
Has anyone ever tried to estimate gold content of different connectors?

I've counted the percentage on 7-8 different fully plated rf connectors and i've found that it was 0,6-0,8% by mass for all of them.
Thats what i've thought....
How can a manufacturer estimate gold content of each of them?
I think they make a detail's surface according to some percentage and weight of the detail (kind of production costs planning).
That's the way it was done in the Soviet Union long long ago(I know that because my dad was designing some of the soviet chips and connectors).Maybe U.S. manufacturers have the similar system. 

Thoughts and estimations are welcome.....


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## Baja Bob (Jan 25, 2008)

Gentlemen, I have been testing some scrap material, gold connecting pins and unused gold plugs. I used aqua regia for the test, the aqua goes to green when the items are introduced and heated, when the stannous chloride solution is added to the test paper, there is no reaction, concurrently I ran a test tube with some known gold in it which did turn purple so I know my solutions are working. Could it be that: 
1) the materials contain no gold, 2) that there is insufficent gold in the scrap to register with the AR and stannous solution, 3) the green in the solution ( copper ) is masking the gold and confounding the test or could there be another answer, any suggestions would be appreciated,thank you for your consideration. Baja Bob


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## lazersteve (Jan 25, 2008)

Bob said:


> Gentlemen, I have been testing some scrap material, gold connecting pins and unused gold plugs. I used aqua regia for the test, the aqua goes to green when the items are introduced and heated, when the stannous chloride solution is added to the test paper, there is no reaction, concurrently I ran a test tube with some known gold in it which did turn purple so I know my solutions are working. Could it be that:
> 1) the materials contain no gold, 2) that there is insufficient gold in the scrap to register with the AR and stannous solution, 3) the green in the solution ( copper ) is masking the gold and confounding the test or could there be another answer, any suggestions would be appreciated,thank you for your consideration. Baja Bob



Bob,

You should always remove the base metals from the pins before dissolving the gold. The AR is most likely initially dissolving the gold then the base metal of the pins. When the base metals from the pins go into the solution the dissolved gold is precipitated from the solution by the dissolving base metals. The gold ends up as a black or brown powder in the bottom of the solution.

Known good stannous chloride solution is sensitive to several parts per million of dissolved gold.

Base metals will not interfere with stannous, but when in high enough concentrations base metals will precipitate dissolved gold out of the solution.

By removing the base metals first you will save chemicals and increase your gold purity at the same time.

If you processed a pound or more of bare pins you should have a visible yield of gold powder in the bottom of the beaker. This dirty gold powder will require redissolving in HCl-Cl or AR to purify it before washing and melting.

Steve


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## skyline27 (Jan 25, 2008)

It sounds like your stannous might be shot. It has a limited lifespan.


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## Baja Bob (Jan 26, 2008)

Skyline 27, thanks for the thought, I keep a dropper with gold dissolved in aqua regia that I use to test my stannous chloride with each time I use it, so I'm pretty sure that the stannous fluid is working. Baja Bob


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