Bill
Are you sure that the material is FR4 on top and bottom layer?
The reason I ask is I once used Rogers on component side and FR4 on circuit
side and the board had
warp age and the reason was mixing the two material.
Other than that I think your fab shop kind of missed it this time.

-----Original Message-----
From: Kasprzak, Bill (sys) USX [mailto:[log in to unmask]]
Sent: Wednesday, December 19, 2001 8:26 AM
To: [log in to unmask]
Subject: [TN] Warpage in FR-4


Holiday Greetings to one and all,

I have an 8 layer FR-4 board that was supposedly built IAW IPC-6011, Class 3
and IPC-6012, Class 3. The board itself appears to be like any other board,
.062" thick, no unusual ground plane layers etc. After wave soldering this
assembly severely warped. Looking at the bare boards, they are also warped,
but can be shaped into a straight position by bending a little. (I shouldn't
have to do this.)

Not being up to date on board fabrication techniques, was there anything in
the fab process that could lead to a warped board? We're talking a 3/16"
warp over an 8" length.. Or was there something at my assembly end that is
introducing the warp. The boards were run in a titanium picture frame
pallet.

Your thoughts and ideas are greatly appreciated.

Bill Kasprzak
Moog Inc., Electronic Assembly Engineering

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