Electronics > Manufacturing & Assembly

ENIG test pad with/without solder paste?

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colotron:
Hello everyone.

I'm working in a 4 layer pcb with ENIG surface finish, first time I use ENIG (qfn components).
I have some small circular pads for post-assembly testing, and I wonder if it's better to leave the pad with/without stencil opening for solder paste application.

If the pad is not covered with solder, will it affect the reliability of the track? (due to oxidation, corrosion...). I think gold is stable, but reading the black pad issues with ENIG makes me wonder if that is correct.

If the pad is covered, could the flux residue affect the conductivity between the probe and the pad?. If it does I can have false test-fails, but will be preferred over reliability issues

Which option would you recommend? (for leaded no-clean solder paste).

Thanks!!!

mikeselectricstuff:
Definitely no paste on an ENIG test pad. The whole point of gold is a long-lasting finish.
Also the soft solder may cause sharp test probes to stick, or leave solder residues in the probe.

colotron:
Excellent, thank you very much Mike!!!

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