A question on interpretation of the IPC method IPC-TM-650, 2.4.22.

I have a batch of boards 400mm square, which are quite clearly twisted when
held free in my hands. When I lay a board horizontal, it straightens under
its own weight. All corners touch the plane and I am left with a small
residual bow of 1 to 2mm, say 0.25 to 0.5%. 

My supplier says it is in specification, but my customer (who cannot carry
out the prescribed test on the populated board) comments on the degree of twist.

Questions:

1) Is this the correct interpretation of the test and specification?

2) Should I be concerned?

Regards

John Loveluck
Tadpole Technology
Cambridge
United Kingdom
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