Not sure if someone replied to this already. If so, please disregard.

IPC-2221, which supersedes IPC-D-275, says:
Unless otherwise specified on the master drawing, the
maximum bow and twist shall be 0.75% for boards that use
surface mount components and 1.5% for all other board
technologies. Panels that contain multiple printed boards to
be assembled on the panel and later separated shall also
meet these bow and twist requirements.

Lisa Williams
Technical Project Manager
IPC
2215 Sanders Road
Nortbrook, IL  60062
www.ipc.org

>>> Donna Perry <[log in to unmask]> 09/15/98 06:23PM >>>
Hello,

What does IPC-D-275 state concerning pcb flatness (bow and twist)?

We are producing a panel (12"x18") of small, unique boards.  The boards
are intended to be surface mounted to larger boards.

I feel a note should be added to the fabrication drawing to specify the
acceptable flatness:

     1) What is the acceptable flatness for boards intended for
automated assembly of surface mounted components?  Would this be
applicable to our boards eventhough they are  the intended
component?
     2) Should the flatness requirement be applied to the entire
panel         or to the individual boards?  (The boards will be shipped
still         in the routed panel.)

TIA, Donna
RadioConnect Corporation
Culver City, CA

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