Steph,

General composition of over 99% of all positive resists.  1) about 10% solvents
alcohols. molecular weight up to 200. 2) About 40% sensitizer usually a diazo
quinone molecular weight up to 5,000.  When this is exposed to U.V. light it
breaks down to indene carbo-oxylic acid. About 50% polymers usually a
Formaldehyde with a moleculer weight up to 60 to 80 thousand. When the resist
ages the polymer grows to molecular weight over 100,000 and it settles out of
the resist into gel slugs.  When you expose the resist and wash it in a basic
solution Tetra Methyl Ammonium Hydroxide it preferentially eats the acididc
areas.  You develop the exposed areas.  Hope his helps. Bill Moffat Yield
Engineering Systems