I would suggest taking the desired board and place three 0.125 inch high spacers at the three corners of the board on a granite table. All three spacers must be exactly the same height and the height must be known. The board should now be elevated off the table by a known height (the spacer height) . Not you can use a surface gage to run along the edges of the board and determine the variation in height. The actual calculations for warp and twist are contained in IPC-TM-650 Test Method 2.4.22.1c. It can be downloaded from http://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2.4.22.1c.pdf

>>> [log in to unmask] 10/06/04 09:35AM >>>
I too placed an inquire to the TechNetters about this Task.   I did not
receive an adequate response.  Good luck

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Karnwal, Pankaj
Sent: Wednesday, October 06, 2004 7:14 AM
To: [log in to unmask] 
Subject: [TN] Twist & Bow

Dear Technetters hello,

Any body have the procedure for measuring the twist & bow as IPC 610 B
says
the .75% allowed for SMD populated module.
how we measure this .75 % , in respect to what ?

BR
Pankaj Karnwal
Jr. Engineer QA

Barco Electronics System  (P) Ltd.
mailto:[log in to unmask] 
www.barco.com 



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