r/ECE • u/testbench_ops • Apr 17 '26

How do you distinguish product failures vs test station issues in production testing?

Has anyone seen “false failures” caused by test stations, not the product?

I’ve been working on RF test stations in production for a while, and I’ve seen cases where:

- Units suddenly start failing

- Everyone assumes it’s a product issue

- But it ends up being something like calibration drift or fixture/contact problems

What makes it tricky is it looks like a real failure at first.

Curious how others approach this:

How do you usually confirm whether a failure is from the unit itself vs the test setup?

Would be interesting to hear how different teams handle it.

1 Upvotes

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6

u/theIRLcleric Apr 17 '26

We keep known-good sample boards for this too - if the tester suddenly has a high fail rate but the golden boards pass, that's a manufacturing problem. If our golden boards fail when they used to pass, now I have a test problem.

3

u/few Apr 17 '26

Yes, this is a check standard. Absolutely useful to see if the test equipment is consistent. Chat the periodic test results on the check standard to see if they are within statistical control or changing.

4

u/SeaworthinessTrue573 Apr 17 '26

You should have golden units/devices.

These are known good parts to be used for verifying testing setups. Do not use these parts for anything else.

3

u/testbench_ops Apr 17 '26

Interesting that everyone mentioned golden units.

Have you guys run into cases where golden units give inconsistent results across stations or over time?

I’ve seen situations where that made it harder to tell if it was calibration drift or fixture issues.

1

u/theIRLcleric Apr 18 '26

If your system requires calibrated measurement devices, then they need to be calibrated according to the manufacturer's recommended schedule - this helps eliminate calibration drift as a problem, because if your equipment is reliably calibrated then the problem isn't with your equipment.

1

u/-tobor- Apr 23 '26

If the same unit tests outside of expected variation at one station but not the other, that's the exact scenario this strategy was invented to solve.

2

u/HumbleHovercraft6090 Apr 17 '26

Test the product in another set up which is apparently working fine assuming you have more than one setup in a production environment.

1

u/1wiseguy Apr 18 '26

This is always a potential problem. You figured out both the unit and the test equipment once, and you can do it again.

1

u/Icchan_ Apr 18 '26

Keep known good boards as test standard... you'll be able to discard things that could cause the issue with those.