Is PCB testing of all nets after assembly required?

That is my first time asking an assembly house to produce 200 units of a PCB (and not the usual 3 or 5 PCBs). The assembly house came back to me saying that the testability of the board was bad and that they need to have 1.2 mm pads on the bottom side of the PBC for all nets... They require such large pads because beds of nails are a much more economical option than flying probe for 200-400 units since they can do it in-house. Is adding 1.2 mm pad on ALL nets common practice for PCB?

PCB Assembly, PCB Testing
October 26, 2023

Putting in those pads the first time round is called DFM (Design For Manufacture). And it sounds like they’re giving you a good price on the bed of nails.

Either get this flow working (it’s perfectly normal) or ask your next fab house if they have a flying probe tester in house.

One way to economize is to use the bed of nails ONLY for nets that don’t already have connectors attached and to break out test cables from those connectors to their ATE.

I do this for my own projects for small runs, where I don’t mind adding the time spent plugging/unplugging connectors to the test time. It can save money on the fixture. but it’s a pain and makes the test more expensive. You can ask them if this is an option, but I wouldn’t be surprised if they refuse.

Yes, there are other test options: as well as the flying probe, there are 2-sided versions of the bed of nails which saves the need to bring all nodes out to the test side … but you don’t want to know the price!

#PCB Assembly #PCB Testing

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

What Others Are Asking

Why aren’t components in DIP package shipped with straight pins?

I’ve noticed that all DIP packaged devices have pins which are at an angle other than 90∘ and need to be bent so that the angle is right for insertion into holes on the PCB or wherever. Is there any reason other than tradition for that?

Oliver Smith November 2, 2023

How do I remove kapton tape from soldered parts in bulk?

I have a batch of PCBs with SMT nuts which has been assembled onto a PCB – the nut has kapton tape on top to allow easy pickup for assembly. How can we do this faster/what’s a better method?

Oliver Smith November 23, 2023