Probing the Impossible

In electronics, you may find that there are times that things do not always work as they are expected. When things like that happen, you need to investigate.

One method of investigating is checking for continuity. This is done by checking resistance between two parts. Most parts are large enough to touch a standard probe to the pads in question. However, what if you wanted to test a connection for continuity but the pads were impossibly small? The solution: use needle sized probes.

Needle sized probes may be good enough to use, but as I didn’t have these at the time, I had to be innovative and used something just as good, albeit, more difficult to use, a sewing pin that is 0.57mm in diameter connected to alligator clips.

I had to check the continuity for a part that is half the size of the quarter in the pic with the sewing pin.

As you can see below, the tip of the needle is as big as the lead on the IC.

On the other side, the connector is even smaller than the IC.

so… the sewing pin saved the day again.

As you can see from the above images, even though the sewing pin is about 0.57mm diameter in the pin shaft, the tip is even smaller. Just look at how tiny the pins are!

Hope this helps anyone that has an issue such as this and needed to probe the impossible.


Sounds like a fantastic tip I will have to try myself. Easy, cheap, quick and dirty!

We need to stop using small parts. Let us go back to through hole :sob:

says the king of drag soldering !!!

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Now let’s play guess the part :rofl:

48pin QFN?

Funnily enough, I just bought a set of those exact gold plated needle point test leads from AliExpress but sadly, they don’t fit into my nice new shiny bench multimeter. :frowning: