In a message dated 97-03-10 19:48:07 EST, you write:

>I am trying to determine reasonable parameters in my pre plate cleaning 
>operation.
>The first thing I need is a way to check the performance of the cleaning 
>solution.  We recently had a bath go bad early but it met all the tests we 
>were doing.  We check with a titration method recommended by the vendor as 
>well as a specific gravity check.

The correct answer to this question is TOTALLYa function of what chemistry is
in your cleaner tank.  Some cleaners are sensitive to levels of dissolved
Copper.  Frequently pH can be more important than titration.   At the end of
the day, it may not be possible to control for all the things that CAN make a
cleaner go bad, but your vendor should be in their pitching madly, because
only the vendor really knows what is in the  bath, and thus what can make it
go wrong.

Another area that we have seen go off, is rinsing.   We have seen occaisions
where the rinse got contaminated, and the changing of the cleaner gave it
enough time to recover.  You may want to consider something simple, like
monitoring pH of the (final) rinse before microetch.

>The other thing I would like to know is what is a reasonable amount of
copper
>
>to remove during a micro-etch process.  Also what would be the maximum that 
>would be expected to be removed.  We currently run between 25 and 50 
>microinches per minute with a two minute cycle.

Sounds if anything, like you may be on the long end of the industry standards
on amount of Copper removed in microetch.

Rudy Sedlak
RD Chemical Company

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