IPC-T-50, Terms and Definitions for Interconnecting and Packaging Electronic Circuits
Warp: See "Bow"
Bow (Sheet, Panel, or Printed Board): The deviatioin from flatness of a board characterized by a roughly cylindrical or spherical curvature such that, if the product is rectangular, its four corners are in the same plane. See twist.
Twist: The deformation of a rectangular sheet, panel or printed board, that occurs parallel to a diagonal across its surface, such that one of the corners of the sheet is not in the plane that contains the other three corners.
You can get a free download of IPC-TM-650 Test Method 2.4.22 Bow and Twist from the IPC Web Site. There are two illustrations the show bow and twist. Jack
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Jack Crawford, IPC Director of Assembly Standards and Technology
2215 Sanders Road, Northbrook IL 60062-6135
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847-790-5393
fax 847-509-9798
>>> "Keel, Mike" <[log in to unmask]> 06/12/00 07:30PM >>>
Hi Mike
In Y14.5
Sec. 6.4.1 deals with straightness which references "bow" (6.4.1.4).
Sec. 6.4.2 deals with flatness.
You are right they are different.
They can be additive.
Good Luck
Mike
-----Original Message-----
From: Mcmaster, Michael
[mailto:[log in to unmask]]
Sent: Tuesday, June 13, 2000 1:03 AM
To: [log in to unmask]
Subject: [TN] Warpage, Flatness and Surface Profile
I have a customer with a specification for bare board
warpage, but the part
also has flatness and surface profile requirements on the
print. The
warpage requirement is in the customer's specification,
which also says that
any print requirements supercede the spec.
Are flatness and warpage the same thing? Or are they
additive? If the
flatness spec is based on Maximum Material Condition do I
get to include the
warpage as separate MMC condition that's in addition to the
flatness
requirement?
I've never been able to find anything in the ANSI Y14.5 for
warpage, bow or
twist which are the terms most of us are familiar with.
Can anybody help
me out here?
Mike McMaster
RF Product Engineer
Merix Corporation
Forest Grove OR
503-992-4263
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