Your proposed requirement is equivalent to the current IPC 6012 spec
(0.75%) for boards 6"x6"or smaller.  What would be your maximum board
size?  If 18"x24", .065 would be equivalent to 0.27% for bow and 0.21%
for twist.  I have a panel that size at my desk but no pin gages to
measure the deflection.  I also have a micrometer and paperclip that is
0.035" thick and it won't fit under the board anywhere so this board
would meet your spec.

A good design with balanced construction can probably be built to your
spec, but you can expect a lot of questions and even resistance when
people see your requirement.

If your designs are unbalanced, it can be difficult to meet the IPC
standard much less something more stringent.

> ----------
> From:         Richard Hamilton[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Wednesday, April 21, 1999 12:03 PM
> To:   [log in to unmask]
> Subject:      [TN] Bow and Twist
>
> Hello TechNetters,
>
> I really hate to beat an almost dead horse to death, but........
>
> I would like opinions on a requirement for Bow (Warp) and Twist that
> calls
> for .065" maximum on any size board. Is this unreasonable? Can it be
> done?
> Does it require more than normal handling? Does it require excessive
> extra
> handling?
>
> As usual, Thanks in advance for your assistance!
>
> Richard Hamilton
> Clemar Mfg. / Rain Bird
> [log in to unmask]
>
>

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