Hi Ted,
I am fully aware of the problem that you describe. We had the same problem here
at our facility in the past. There is a couple of things that seem to
exacerbate the problem. 1) Too much defoamer in the developer seems to cause a
long chain polymer to be created which may be carried from the developer into
the etch chamber. 2) The particular resist may also be more prone to cause the
problem.
3) The absence of a dryer between the Developer and the Etcher can also
contribute.
One way out is to place a dryer module between the Developer an the Etcher This
will go a long way to eliminate the problem.
The fix that we put into place was twofold, 1) We decreased the Defoamer
significantly and 2) we switched the resist. We used dry film resists, from a
different supplier than you do there, but initially had the same problem. I'll
not go into the paticular resists we used to avoid a commercial for the
product, however if you would like to explore further you could contact me
direct. I believe that these fixes might be appropriate for you, Incidentally
the carbon filters are a very positive step also.
Lots of Luck,
Les Connally,
[log in to unmask]
PS. for other Technetters including Jerry Cupples and Marie Holmgard, please
let me know if the "Attribs.bnd" extensions show up now. I have taken steps to
eliminate them.
Thanks,
Les
> From: Ted Stern <[log in to unmask]>, on 1/12/98 4:32 PM:
> Hello All:
>
> I need help trying to minimize "organic" contamination occuring in a
> cupric chloride final etch. The contamination is a "black", gummy
> material which floats on the surface of the bath in clumps. If the line
> is not cleaned periodically, black spots on the surface of copper
> (typically not the laminate), can be seen in inspection.
>
> The DES line processes only innerlayers utilizing CibaGiegy (0.9 mil
> nominal thickness) and Dyanchem FL 1.3 mil photopolymers as etch
> resists. An FTIR scan has been performed on the residue, both
> photopolymers, and the "rollers". While not entirely conclusive, the
> scans more closely resembled the photopolymers and not the rollers.
> Visually, the rollers do not seem to be swelling or deteriorating.
>
> The etching bath is operated at 1.3 N HCl, regenerated via chlorine gas
> (ORP control), and sees both 1 oz and 2 oz copper. I am unsure of the
> laminate being employed. Continuous carbon filtration has been employed
> with some degree of success. The carbon filters are changed weekly:
> one 30" filter per 450 gallons of bath.
>
> Can anyone offer suggestions to better control or eliminate this
> residue?! Thanks in advance
>
> Ted Stern
>
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