Franklin,

One test I perform as a spot check to evaluate debris under the resist is to
look at a core after resist exposure for dents/debris/scratches...etc...I
mark the cover mylar by circling any suspect spots with a good ol Sharpee
marker and then run the core through my developer.  I then overlay the mylar
sheet keeping orientation the same as the original, and then observing the
circled areas.

This simple non empirical test gave us insight into how our material was
being handled.  It seems our lifting when we had it came from slight dents
and creased cores that could not conform to the resist allowing for resist
lifting.

Typically we use RTF foil, and a chemical clean process (no microetch)  Talk
to Rudy Sedlak of RD Chemical about it.  We get great adhesion with minimal
loss of copper (read as no increase in overall surface topography) and still
obtain excellent conformation on 1.5 and 1.2 mil resists.  I hope this helps
you out.

The only problem with my test is that it requires a person to visually
inspect a core for debris and dents on an imaged layer...Tough to do even if
you are good at it.  Happy hunting.


Sean Clinton
Sanmina Plant 3
Santa Clara, CA

Franklin D Asbell wrote:

> Yes, been spending much time in there...The lifting is isolated to very
> small areas (in comparison to the panel size) around .050".
>
> Of course it is identified under trace's after developing (AOI) and etch
> (AOI and visual inspection).
>
> My thoughts are it is also debris trapped under the resist and not a
> contaminate of the copper itself, if this makes sense.
>
> Any advice from all of you on DOE's performed in this area would be
> helpful, I'm developing one at the moment but want to make sure I
> include appropriate variables.
>
> Thanks,
>
> Franklin

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