At 04:19 PM 2/19/96 PST, you wrote:
>
>We are currently using a 2 layer FR-4 board as a 2-up panel in our assembly 
>factory and our board vendor has asked us if we are able to use x-outs. 
> Currently, we are not able to use x-outs given our equipment and line rate. 
> They say that this problem is causing 6%-8% fallout and want to increase 
>our cost.  Consequently, our vendor has asked us if we can accept boards 
>that have two good boards glued together into a panel.  They claim that 
>there will be little difference between the panels and want to move forward 
>with a trial run.
>
>Does anyone else produce / use glued boards?
>Is this fallout unusually high?
>What are some problems we should look out for?
>
>Any information is greatly appreciated!
>
>Karl Kaylor
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>
>
Karl;

I can't help you with the glued boards. However I do have some questions and
concerns. Printed board yield is affected by a number of issues; size of the
board, the copper balance, the line width/space, smallest hole size, type of
solder mask, etc. What I would suggest, is to ask your supplier to suggest
what can be done to the design, to improve his yields. It may very well be
that a small amount of work, on your part, can get his yields up to the
extent where there will be no cost impact, as well as no x-outs. If your
product design is totally frozen, then it may be possible that you have not
adequately matched the technology of the product to the fabricator's
capabilities. I little research, on your part should reveal if this is so.

As far as glued boards, I would be concerned that the adhesive is strong
enough to withstand the forces, during component placement, as well as
enable you to easily excise the finished product from the panel. Another
concern would be the accuracy of placement of the guled board. The
relationship from the panel data, at assembly, is critical. With additional
tolerance added to the panel, you may incurr placement problems with the
components.

Regards,

Gary Ferrari
Tech Circuits
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Gary Ferrari
Tech Circuits