hi,

have you sent 'bare' (no components) versions through your reflow oven?  if you have, did they warp also?  if not, you might want to do this to see if the boards or their layout geometries are the problem.

phil

-----Original Message-----
From: Steffen, Don E [mailto:[log in to unmask]]
Sent: Wednesday, May 17, 2000 3:31 PM
To: [log in to unmask]
Subject: [TN] Board Warpage


Technetters

We are having a problem with board warpage. The board material is FR4. One
board is double sided and the other is 4 layers. Appears that the double
sided board warp more the four layer. We tried reducing the cooling portion
of the reflow oven and this did not help. We are using paste that is a 63/37
mixture so are using a normal thermal profile...... The question is: Is
there board material out there in the industry that would warp less than
others? Are there other process variations that we can consider to lessen
the warpage? This board is depaneled via a punch versus a router. We have
reduce the size and number of tabs in order to reduce any induced
microstrains shocks in the circuit. I would appreciate any guidelines if
there are any out there.

Thanks

Donn Steffen
Wk# (219)925-8887
Fax# (219)925-8710
Email: [log in to unmask]

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