General > General Technical Chat
In general, what happens if a PCB house totally screws up your big $ PCBA job?
Psi:
Don't worry, this has not happened to me yet.
But I do have a rather costly (at least for me) PCB order coming up and I was just curious what actually happen in the case of a total screw up by the PCB/PCBA fab.
Lets say an inner layer VCC to GND short in 50 places (their fault). Something that is not fixable in any way.
You get delivered 250 boards with $40k of parts on them that are totally useless.
For the purpose of this discussion we will assume the PCB/PCBA fab is in china and you are not.
What happens?
nctnico:
You wish you paid extra for electrical testing of the PCBs... don't skimp on that. If it is not specified then ask for it.
What you can do yourself is to add an extra 3% of margin to your PCB design; don't make the traces as thin as the production process allows but make them a little bit wider. Same goes for minimal distances, annular rings, drill sizes, etc, etc. Where you don't need minimum widths / holes sizes / distances, make then bigger.
When I order expensive boards for the first time, I let the assembler make 2 prototypes which I test thouroughly before giving the go-ahead for the rest of the boards. However I work with local assemblers only. For 250 boards there is no use to go to China and take chances.
AndyC_772:
This is why you order complete, assembled PCBAs from your supplier, and let them procure the bare boards themselves. If they arrive with fabrication faults, which mean your components are wasted, it's 100% on them.
If you buy the bare boards yourself and free-issue, your assembler is not responsible for them. If they turn out to have faults, you may be able to recover the cost of the bare boards from the fabricator, but that's all. You'll end up eating the entire cost of parts and assembly yourself.
Changing track and gap sizes really won't make any difference; a scratch on a photo plot will easily break multiple traces whatever their geometry.
Bare board electrical testing is absolutely mandatory, but still not a guarantee the boards are good. My company once found a ~25% failure rate in a batch of assembled boards, which was eventually traced to a scratch on one copy of the artwork for a PCB which was made 4 up on a panel. The moron doing the testing had decided to exclude the affected trace from the electrical test 'because it was always failing'.
tszaboo:
There are a few things you can do to avoid this:
1) Dont order from China, order it from a local fab where you have contractual agreements.
2) Let your assembly house order the PCBs
3) 100% electrical test, and prototypes. Order the prototypes from the same factory and process as the production.
I had PCBs in the past, that were faulty. It a question of when that happens, not if, when you done over 100 projects. It was caught before assembly, sent pictures to the local PCB fab, they sent new PCBs in 2 days, free of charge.
I also had messed up gerber files, which got corrupted during export. So get prototypes. It's going to cost more for each projects, until you find a mistake, and then it suddenly doesn't cost more.
And get used to the pressure. Usually I handle projects that cost several times my salary, only way to get good jobs. Get somewhat detached, "This is someone else's money". It is not worth to loose sleep over it. On the long term this is more healthy. Just let your managers have the final say on where you order from, and how to protect against failures, and if something goes wrong, you can always raise your shoulders and say that they decided.
jmelson:
--- Quote from: Psi on November 08, 2021, 07:25:33 am ---Don't worry, this has not happened to me yet.
But I do have a rather costly (at least for me) PCB order coming up and I was just curious what actually happen in the case of a total screw up by the PCB/PCBA fab.
Lets say an inner layer VCC to GND short in 50 places (their fault). Something that is not fixable in any way.
You get delivered 250 boards with $40k of parts on them that are totally useless.
--- End quote ---
Make sure the PCB fabricator does a full electrical test. That should catch any such defect in the board.
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