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Wed, 8 May 1996 18:17:57 +0100 (BST) |
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| From [log in to unmask] Wed May 15 18: |
19:04 1996 |
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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
[log in to unmask]
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