You can stop pink ring further up-stream in your process.  You could 
use a "Post Reduction Oxide".  This type of process, when run properly, will 
eliminate pink ring all together.  This way you are not band-aiding a 
situation that potentially can get out of control and cost you time and 
money in other processing issues.  For example, like mentioned in the reply 
below, you tend to harden the epoxy of the hole wall making it harder to 
remove.  If you are not careful during your bake you can ruin the material 
properties in the hole causing plating issues down the process.  The best 
recommendation is to eliminate the problem.

Todd Campbell
Gerber Systems
 ----------
From: TechNet-request
To: TechNet
Subject: Re[2]: Post Baking Process
Date: Monday, January 27, 1997 12:30PM

     Will someone please clarify the paragraph below ?  It states that pink
     ring can be eliminated with a post drill bake.  It then goes on to say
     that it cannot reseal the crack and it is only a cosmetic fix.  Isn't
     pink ring a cosmetic issue?  Why would it be a dangerous fix if it
     works??

     Also, you can have the best innerlayer treatment out there and if the
     drilling operation is unoptimized, it will not make a difference in
     cracking of inner layers.


______________________________ Reply Separator
_________________________________
Subject: Re: Post Baking Process
Author:  [log in to unmask] at corp
Date:    1/27/97 11:46 AM



Post-drill bake -  A bake after drill has been shown to eliminate pink ring. 

Our work shows this is a dangerous fix.  Pink ring is caused by a chemical
attack on innerlayer surfaces that are exposed by cracks introduced at 
drill.
The bake relaxes the epoxy enough to close the crack, but it cannot reseal
the
crack.  Thus it is at best a cosmetic fix.  However in addition, the bake
hardens epoxy smear and makes it difficult to remove.  A much better 
solution
to pink ring is to use a good innerlayer surface treatment that prevents
cracking at drill.


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