I and one of my colleagues in reliability group were arguing the sample
size and its statistical significance. Can you help us? Our arguments are:

1) What is the sample size industry typically use for BGA solder joint
reliability test? 32, 40 ...? Why use this size?

2) Is lognormal distribution a good one to fit the test data? If yes, is
0.1% value of the lognormal fit a good representation of failure free life
of the whole population?

Appreciate your help in advance,

Dr. Yuan Li

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