Defect Rate WRT Customer Deliveries

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My company is a small CM that is going through AS9100 certif... - Mar 07, 2024 by kyleh04

If you have any kind of inspection, record any faults found.... - Mar 08, 2024 by MagyarT

That makes a lot of sense, thank you for the answer. Do you... - Mar 08, 2024 by kyleh04

Unfortunately no sample numbers. We are building our own pro... - Mar 08, 2024 by MagyarT

kyleh04

#90662

Defect Rate WRT Customer Deliveries | 7 March, 2024

My company is a small CM that is going through AS9100 certification. We've been working to nail down some metrics on our defect rate for SMT and THT assembly. I've seen numbers like 100 - 500 PPM defect rates. On a recent job, if I count each component as one potential source of a defect, then we had a defect rate of around 100 PPM.

The issue I've run into, is that all metric information I've found online bases the PPM rate on defects found by an end of line AOI. This seems flawed to me for a few reasons:

1. This assumes that a AOI is 100% accurate, which as we all know, is not true.

2. If a board is not functionally tested, the only real way to know if there is an assembly defect, is when the end customer/client actually uses/tests the board. Which if you base your defects only on your AOI, this rate is not captured.

Ultimately, if we are building boards for a client, with no functional test fixture provided, it is, of course, not possible to deliver 100% of the boards, defect free. So does anyone have any sort of guidance or information that they use to benchmark this? Because if we base it off of my 100 PPM defect rate, if a board has a few hundred components, that means that there will be a couple of percent of boards delivered to the client that will need to be RMA'd back to us to rework.

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MagyarT

#90666

Defect Rate WRT Customer Deliveries | 8 March, 2024

If you have any kind of inspection, record any faults found. If you've got an RMA process, record any faults found. Should rework and/or RMA's hit unwanted numbers, you may want to include additional inspection in your product documentation during build, in your company. Use the data gathered to investigate and prevent the faults.

Perhaps investing in AOI, and or convincing the customer to allow you to use the test fixtures can be another idea.

If you want to accurately test your AOI program, you need 3 boards, 1 golden sample (100% good board - this must pass), 1 silver sample (generated faults on board, listed up - these will need finding by AOI) and 1 bare board soldered (all components must be seen as missing by the program). If your program passes these 3 tests, you can be sure it is accurate enough.

Hope this helps.

Regards, Tom

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kyleh04

#90668

Defect Rate WRT Customer Deliveries | 8 March, 2024

That makes a lot of sense, thank you for the answer.

Do you have any sample numbers you can share? Like if you build a batch of boards with no functional testing, are you normally expecting 100% pass rate when the reach the customer?

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MagyarT

#90669

Defect Rate WRT Customer Deliveries | 8 March, 2024

Unfortunately no sample numbers. We are building our own products, not a contract manufacturer. We are monitoring AOI, RMAs and rework - this only started in the last couple of months, but top management inclines not to give a target as it may "upset" people...

However, in the past when I worked at a global contract manufacturer, the average expected pass rate between customers was 85% - some were stricter, some were not. But if they are expecting higher pass rate, they should allow you to use their test jigs inhouse. It is beneficial for everyone - you could suggest allowing them access in your test database.

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