George,
The most common reason for warp and twist is tempter. If a board
cools unevenly then the board might warp and twist. Best way to avoid this
is to make sure that your layer stack up must be symmetrical apposed to
asymmetrical.
(S,S,P,S,S,P,S,S correct/ S,P,P,S,S,S,S wrong). If the edges of the board
cool before the center has a chance too then it will warp, after lamination.
If this is the problem then you should be able to heat the board up and cool
it down slower and relive the problem. It can also be that there is an
uneven amount of resin on the board.
I hope this answers you question,
Ted
-----Original Message-----
From: Nancy Trumbull [mailto:[log in to unmask]]
Sent: Friday, March 16, 2001 5:42 AM
To: [log in to unmask]
Subject: Re: [TN] twist and wrap issue
Sorry George,
What it is you what to know.
Your question is not clear.
Nancy T.
>>> [log in to unmask] 03/15/01 09:31PM >>>
Hello, Everyone
Does anyone kindly help me explain the reason for wrap and twist of rigid
PCB?
I'm appreciate your generous guidance and your any advice.
George Chu
Quality Dept.
Phone: ++86 512 5651961 ext.6201
Fax: ++86 512 5613446
Email: [log in to unmask]
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