Hi Josh,

        I'm not sure what the definition of an average inner layer etch line
is, but I can provide some information.
        The parameters to track are as follows, but not limited to those alone:
        1) Normality -- We run a normality of 2.6 here, but if you are looking
for a better etch factor or fine line improvement, I would suggest a
normality of 1 - This will etch slower but provide greater quality.
        2) Oxidation/Reduction Potential (ORP) - for the most stable etch rate
420 to 460 millivolts.
        3) Copper content - Usually controlled by Baume' or specific gravity.
           This can vary somewhat but about 20g/liter or a Baume' of about 32
        4) Conveyor speed - Equipment dependent
        5) Etch rate or weight loss from a fixed size coupon. Evaluate top to
bottom variability.
        6) Spray pressures. - again equipment Dependent (est. about 30 PSIG)

I hope this is of some help, If you want to pursue further, contact me off
line.
Regards,
Les

>  From: [log in to unmask], on 11/6/98 12:33 AM:
>  I'm new at cupric etching.  What are the parameters for the average
>  innerlayer
>  etch line?  What controls should I be monitoring, for example, normality,
>  copper content, etc? What ranges will provide me the best process in terms
>  of
>  etch line quality (minimum copper foot with best possible line width
>  uniformity and etch speed)?  I know equipment has a lot to do with the
>  results; we can't change equipment, so I'm looking to improve quality with
>  chemistry.
>
>  Thanks.
>
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