FEDEVEL
Platform forum

Brunodrt , 01-09-2021, 07:40 AM

Hello All,

So I'm finishing a board and I wanted to add some test points in order to facilitate the debug of it. the purpose is for debug only and not automated testing so the test points ideally should be on the top side.
My concern is what kind of test point should i use and how should I place them on the signals.

So for the higher speed nets ( Coms - CAN / RS232 ) i was thinking on using 100mils tespoints over the track whenever possible. If not possible do you guys think it can be a issue to add a stub / via for the test points ?
For the remaining signal ( power / LF Signals ) I was thinking on using though hole test points since is easier to attach a oscilloscope probe. In this case, the via should be placed close but not on the track itself right ?

Thank you.

Best Regards,
BD

robertferanec , 01-11-2021, 02:04 AM

I hope this helps:

- I often use two types of test points: a 1mm/40mil pad or a an unmasked VIA. However, usually our boards are very space limited, so you may want to use bigger test points (your suggested 100mils can be fine).

- Especially if I may need to solder a wire to that test point, I prefer to use a VIA (if a wire is soldered to an smd test point, that testpoint can be pulled of the board and damage the testpoint or track - via is much stronger)

- I always try to avoid stubs, however I do not think a short stub on RS232 would be a problem. Normally I place testpoints over the routed track (so no stubs). If I use a VIA as a testpoint, I just use it at the place where I would need to use a VIA to change layers when routing the signal, so there is no extra stub.