Eric,


I have to concur with the two recommendations given by Rudy and Brian.
And of course, their assessment of the situation.  I was curious how
your results would be if you turned off your pumps in the replenisher
chamber.  You could then run a double pass through your main chamber if
needed.  This may affect your side walls, but I cannot say to how much
of a degree.  You may get  away with two passes through your etch
chamber without breaking down the resist.
Aside from that, I would really push for cupric etching if given the
chance.

Good luck,

Sean

Eric Masters wrote:

> I am having some difficulty with dryfilm breakdown on heavy copper
> etching.
> I have tried a number of different films, and they all work on copper
> weights
> less than 3 ounces.  Above three ounces, I begin to have breakdown
> issues in
> the etch replenisher chamber.
>
> I have maximized all the process parameters for dryfilm:  surface
> prep,
> lamination exit temperature, exposure, and developing.  I am convinced
> that
> the problem lies with the etching chemistry, but I'm not sure what
> parameter
> contributes most to breakdown.
>
> Does anyone know which component is the most troublesome?  or is it a
> combination of things?  I've tried varying pH, copper concentration,
> chlorides, and controlling free ammonia in the replenishment chamber.
> Any
> suggestions will be appreciated.
>
> Thanks.

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