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August 1999

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Subject:
From:
Dave Hoover <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 26 Aug 1999 08:46:48 -0700
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Tom,

Are these doublesided or multilayer PCB's????
Tell us alittle about the board.

Groovy
-----Original Message-----
From: Tom Oliver [mailto:[log in to unmask]]
Sent: Thursday, August 26, 1999 8:03 AM
To: [log in to unmask]
Subject: [TN] PCB material shrinkage


Hello
My first post and first question to the experts.
I am new to the electronic game most of my experience has been in mechanical
inspection and test.
My question: is there a rule of thumb on material shrinkage on board
material or a spec. Our boards are coming in with all the dimensions at
nominal but after wave they have shrunk down to the low limit and sometimes
below low limit. Most of our tolerances are +/- .003.
This is giving us headaches with interference problems when we put other
components on the boards.
Is it normal for the boards to shrink. Our arrays are approx. 4" x 12" with
25 separate boards on each array.
Thx's in advance
Tom Oliver
Eagle Comtronics
[log in to unmask]

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