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December 1997

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Subject:
From:
Pat Bailey <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Mon, 15 Dec 1997 16:48:15 -0600
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Hello, TechNetters,

I was wondering what others are calling out for flatness requirements on
double sided boards with surface mount components.  IPC-A-600 calls out
1.5% but with a caveat that automated assembly and surface mount may
require more stringent requirements, and refers to IPC-D-275.  The most
stringent callout in D-275 for a 0.062" double sided board is 0.9%, and
this is classed "reduced producibility".  If we have, say, an 8.5"x11"
board with 0.9% bow or twist, I know we'll have difficulty running it down
our lines.  What are others calling out, and how have your fabricators
responded?  Some of mine are balking at 0.7%, saying it can't be held
(would have to be sorted, possibly increasing cost) because of variability
in the base material.  I think 0.7% is met most of the time, but every once
in a while...

Thanks for any input.

*****************************
* Pat Bailey                *
* Supplier Quality Engineer *
* Zytec Corporation         *
* 1425 E. Bridge Street     *
* Redwood Falls, MN  56283  *
*                           *
* phone 507 637-2966 x355   *
* fax   507 644-3720        *
* e-mail [log in to unmask]     *
*****************************

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