Your bake after oxide and prior to press should be sufficient to remove
any moisture absorbed at etch. In a nutshell your process will be, etch,
AOI, oxide, bake, press. This is what we have been doing since
installing a post etch punch in our process about 6 years ago and have
not seen any problems related to moisture. Hope that helps!
Rick Howieson

>-----Original Message-----
>From:  Craig Ropp [SMTP:[log in to unmask]]
>Sent:  Friday, October 29, 1999 4:32 PM
>To:    [log in to unmask]
>Subject:       [TN] Baking Boards before Post Etch Punch
>
>¯-----------"Help"!!!!
>We instituted a baking step before Post Etch Punch approximately 1 year ago.
>This was done (I am told) because we had just started using the PEP machine
>as part of an overall tooling upgrade. The bake was added because there was
>concern that there may be some moisture absorption at the Etch process which
>would have impact dimensionally in conjunction with the dimensional effects
>we typically see from Etch. The PEP is a CA Picard machine which punches 4
>slotted tooling holes in the innerlayers. These tooling holes are supposed to
>allow for  self-centering so that at press the innerlayer can move without
>building up stress. This innerlayer then goes through the Oxide line and
>receives another Bake before Press. 
>We now have acquired a Barco AOI and are experiencing difficulty because the
>bake  before PEP darkens the copper and makes it harder to inspect. The
>Production Folks want to drop this Bake Step. MY QUESTION IS: What is the
>risk in doing this? If I've learned one thing in the Printed Wiring Board
>Business It's not to make changes lightly.  And if you do make a change watch
>it like a hawk! Your input would be appreciated. 
>Thanks,  Craig 
>
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