[log in to unmask] wrote:

>     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.

I would agree that it can be a dangerous "fix".  You will have a hard time
resolving the debate over whether or not pink ring is only a cosmetic issue
in this forum.  That has been debated so long that if the post-dips for oxide
had not been introduced, someone was going to have to suggest arm wrestling
to resolve the question.  

In any case, the original post mentioned that the fix was dangerous in that
the crack was not resealed and drill smear could be hardened.  I would add to
this the fact that the fix does not always work anyway.  The theory that you
can melt the epoxy to reseal the crack is as dangerous as saying if you create
more drill smear it could seal a crack.  

As someone who performed way too many DOEs on the problem many years ago, I 
can tell you that baking at any stage is not always a reliable fix.  There 
are many changes you can make in drilling to reduce pink ring, as are there
many lamination, plating, and oxide changes.  I would be happy to detail 
some of these that Merix found (back when we were Tektronix) if there is 
still interest in pink ring.

Glenn Heath
Merix Corporation
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