Hello Steve,

Depending on the configuration of the baking oven you will be using and
the number of panel per stacks,  you must set baking temperature above
the Tg of your material and allow enough time for that temperature to be
reached in the middle of every stack of panels.

Once this is done, the key to this baking process is the cooling cycle,
if possible, panels must be allowed to cool slowly so the internal
stress of the material will be distributed uniformly across the entire
surface of panels. If you try to cool them down to fast, it is very
possible that you will achieve nothing to improve the Bow & Twist
condition of your panels.

Regards,

Charles Desroches
Technical Advisor
Viasystems Granby
Voice:  450-372-8111 (2257)
Fax:    450-378-5110

> -----Original Message-----
> From: Steve Collins [SMTP:[log in to unmask]]
> Sent: Tuesday, July 14, 1998 12:53 PM
> To:   [log in to unmask]
> Subject:      [TN] Fab: Bow & Twist
>
> We have several boards that are single sided with massive grounds on
> one
> side. I know this is not the correct way to have designed this board
> but it
> was designed many years ago and it cannot be changed easily at this
> point.
> The problem is extreme Bow and Twist and the material is FR-4. In a
> past
> life I remember situations like  this and we would have the boards
> baked
> but I have over the years lost the baking recipe. Can anyone help out.
>
> Steve Collins
>
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