Thanks Russ and John,
To clarify defects when manufacturing a PCBA, I use (2) groups of defect categories, one for components and one for solder joints. These can be calculated separately or combined
A component defect could be: Missing, Miss-aligned, damaged, wrong, polarity, Etc.
A Solder joint defect could be: bridge, open, insufficient, excessive, etc.
For overall combined DPMO I simply sum the component and solder joint counts, the combined sum would be the opportunities.
DPMO is calculated by (sum of defects / sum of Ops)*1,000,000 = DPMO. This can be performed by PCBA, all the boards in a product, or all boards built in the factory
This DPMO number shows me general factory health trend, high hit PCBAs or the product with the highest defect rate.
I have several ways to drill to the hit defect hits by category and by reference designator. By working on the root cause of the top defect hitters, DPMO is continually driven down.
I am looking for a reasonable Overall Combined DPMO Number in which would deem my factory 'world class' (any ideas, someone toss me a number?
As DPMO rates improve, so do your yields, DPMO is a normalized quality indicator, yield is not.
bw
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