Plated pins with solid contacts?

[Slochteren]

Hi

I have +/- 1000 off these pins. The 3 smaler ones are solderd on the gold plated pin, could it be that the 3 smaler ones are solid gold? They are from switches inside a telex machine made in 1983.
Thinking off this what happens with solid gold in a sulfiric cell?

 

[goldsilverpro]

I assume the solid contacts are those small, hard to see, dark rectangles on the contact areas of the 3 pins.

Counting those, I have seen only 3 instances where there were solid points on the contact areas of the pins. The others are on backplanes of old Burroughs mainframes and old IBM cards. I absolutely know that the Burroughs points are 75Au/25Ag. I always assumed that the IBM points were the same, but someone I was talking to recently thought they were Au plated Ag or Cu. Not sure about yours.

It would help to have a well-focused, well-lighted, close up of the points.

 

[g_axelsson]

Easy to check, just cut them in half and drop one contact in a test tube with nitric acid and one in another tube with hydrochloric acid. That should take care of most base metals. If the core is dissolving then it wasn't made of gold.

My guess, some springy gold plated base metal (steel, beryllium copper or phosphor bronze) soldered to the end of an ordinary plated pin. The spring is needed for the contact to stay flexible, most gold alloys aren't known to be excellent springs.

Göran

 

[johnny309]

Spring alike those one ....even if gold plated ....were made from an cooper and Beryllium alloy,nickel plated ...
Sorry ...but the "spring" tension does not apply to gold....it is a soft metal.

 

[Slochteren]

Ok thanks, will run them like other pins thru the sulfiric cell