Recently, I heard of a dry film photoresist developer system that uses sodium
hydroxide as a pH stabilizer.  Apparently, the system doses the developer
sump with  carbonate based on a panel counter,  and sodium hydroxide based on
solution pH.  The sodium hydroxide is used straight out of the drum, probably
at around 40 % strength.    I'm told this controls pH in a very tight range,
and reduces consumption of carbonate.

I have some questions regarding a system of this type.

1.  What would the advantage be of using both chemicals?  Cost savings don't
seem to be too likely, since you are replacing one chemical with another.

2.  What are the potential dangers of using sodium hydroxide in a developer?
 What effects could it have on photoresist?

3.  Does the addition of sodium hydroxide cause bicarbonate to be converted
to carbonate?

4.  How many people are using this type of system in production?

Thank you in advance for your assistance.

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