Electronics > Manufacturing & Assembly

PCB Test Point questions. Solder or no solder

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TheRadioGeek:
Hello all,

I have a question about PCB test points. What is standard practice? Do test points get solder pasted. In other words should test points have solder on them? Or should the test points have no solder on them. Is it better for the test probe to hit a test point with solder or without solder. What are the pros and cons of doing it each way?


Thanks
TheRadioGeek

free_electron:

--- Quote from: blueskull on February 15, 2017, 05:07:33 pm ---Absolutely NO solder. Usually automated test equipment use a kind of pins called pogo pins (which are spring loaded pins) to probe test points.
With solder (and a bulged solder "pillow"), the tip of pogo pins may slip, breaking contact at best, short circuit and kill your board at worst.

--- End quote ---
nonsense.
the pogo pins are very sharp and will poke in the solder without problem.

wraper:
If that is board with ENIG, there is no point applying paste. With HASL, no much difference IMO, if OSP, then certainly yes. Pogo pins may be rounded or sharp. Rounded won't pierce flux residue layer which may cover the solder.

TheRadioGeek:
How bad will the flux build up contaminate the pogos? 

HHaase:
There's no reason to apply paste on a test point if you're not soldering a component to it, unless the pad material isn't compatible with your test procedure.

If you apply paste you'll now have the convex surface of a solder pillow with flux residue on it if you use no-clean. Both conditions can potentially make it harder to test. 
Even with a sharp probe you can potentially have issues with residue from no-clean fluxes. 

I honestly couldn't tell you the last time I've seen a board with solder intentionally placed on a test point.

-Hans

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