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AOI inspection of DNI locations

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AOI inspection of DNI locations | 29 January, 2015

Do any of you use your AOI machines to inspect do-not-install locations? Do you look for solder bridges or stray parts in those spots? Everything I have learned and heard involves part placement and solder quality. But is it worth going that extra length to look at all board locations? Thanks.

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AOI inspection of DNI locations | 30 January, 2015

I'm the AOI operator here, and no, we do not look at DNI locations. It was considered, but overall, the extra time taken is not worth it. You could inspect some locations where components are not to be fitted, but I guess it depends on how many places are DNI. On a small PCB with one or two DNI's, it might be worth it, but on a large 19" rackmount PCB with 1 - 2k parts fitted, and maybe hundreds of DNI's, then I can't see it being useful.

We also considered looking at all other areas of the PCB, mainly to detect stray parts spat out by the feeders, but again, it takes too much time, given the low possibility of this happening.

If you have had a few bits fitted that shouldn't have been, make it part of your first-off inspection instead. When I do a first-off check on a PCB using the AOI, I always scan across the whole PCB just the once. This can pick up bits that were fitted that should not have been. This can easily occur when a PCB gets up-issued, and the line doesn't spot one (or more) bits that should have been removed.

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AOI inspection of DNI locations | 30 January, 2015

Let's put it this way - if you run 10000boards every month, you could probably go this route and have a 100% inspection on everything. I work for a high mix low volume company and we will never do this excessive work. I would always focus my attention on the correct machine programing and good screen printing. If you do these right, the chance to have extra part or short on a DNI location is almost zero.

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AOI inspection of DNI locations | 2 February, 2015


Most of our customers perform DNI check. Some of them give a special focus on the issue when it is a new product (NPI) or change version (ECO/ECN). Our customers perform tests on AOI machine and feed the results into a software tool called TopoQC.This tool maps all the faults by color depending on the amount and you can easily see areas that are not covered in AOI tests.

You can read about a tool on our website:!topoqc/cy96

By the way, our tool is based on measles chart theory.

If you need more information, feel free to send me an email:

Best Regards, Alexei

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AOI inspection of DNI locations | 4 February, 2015

In this case I do frame for empty locations, and machine show me if someone install part on DNI location

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