Guest
 Posted: Thu Sep 11, 2026 10:49 pm Post subject: Why is SS = 45 for Quals? |
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| Why are the sample sizes for quals usually 45? Is this standard for the industry?
Assy Engr 2 |
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Joined: 16 Jun 2026
Posts: 107
Location: Paranaque City, Phils.
| Posted: Mon Sep 15, 2026 1:50 pm Post subject: |
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| Hi Assy Engr 2,
A sample size of 45 is quite popular for quals because it corresponds to LTPD=5, which is the level of lot quality that you will reject 90% of the time if it has a defect rate of 5% and above. In other words, there's a 90% probability that you will catch a lot with 5% failures if you get 45 samples from the lot for rel testing. Of course, if you want higher confidence in your sampling, you can always increase your SS. Pls see: http://www.semiconfareast.com/ltpd_aql.htm for more details. Thanks! EE |
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