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Pre-Tinning gold plated spring contacts suggestions

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vikash23

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Hi,

I am doing a test rig for a PCB.

The PCB finish is HASL lead free finish.

I am thinking about using a spring contacts for testing the PCB's and the spring contacts will be soldered on to a test rig PCB.

The developed PCB will sit on top of the spring contact that is soldered to the test rig PCB

My question is from the following document it is recommended that mating gold contact with tin surface is not recommended and I was not able to find tin plated spring contact.

https://www.ramoem.com/uploads/4/4/0/7/44075859/tin_commandments.pdf

The manufacturer suggested to pre-tin the gold coated contact since they haven't got any non gold plated contacts.

Can anyone please guide me how to remove the gold coating from the spring loaded contacts.

-Vikash
 

I think this is a bad idea. The gold contact is the most
durable (esp. in terms of long term contact resistance)
you will find. Anything like tin will oxidize over time and
need scrubbing to keep bright, leading likely to test
unrepeatability.

Now you might want to look at what "mating" means.
A solder joint under the wrong conditions could
consume a thin gold plating layer (a not uncommon
problem in microelectronics assembly) or vice versa.
But a simple short term physical contact, is not
going to have the energy to make these chemical
changes. The only issue would be whatever is on
the "lead free finish" (which is pretty nonspecific,
otherwise). Pure tin and high tin concentrations
can grow whiskers but this is not the pogo pins'
problem, but a board materials problem.

If I were you, and you weren't driven to the
absolute lowest cost construction (i.e. no gold
was on the PCB) I would think about making the
board test points have gold on them. Gold-gold,
problem solved. But it's a cost adder. The
engineer's question is, how does that cost
compare to test repeatability and test escapes
related costs?
 

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