Hello,

I'm currently working with two negative-type photoresists: an epoxy acrylate resin and a poly(ethylene-co-acrylic acid) resin.

I noticed that during my tests, a soda ash solution (Na2CO3) works much better to dissolve the uncrosslinked resin than a caustic soda solution (NaOH). By 'better', I mean that the uncrosslinked resin dissolves much faster than it does with NaOH. For reference, my NaOH solution is at 0.2 M and my Na2CO3 solution is at 0.1 M. I think the correlation with temperature exists but is not very significant, since using a NaOH solution at 23°C and at 40°C does not change much.

What would this difference in performance be related to, if the resins are otherwise processed in the same way (same UV exposure, same thickness)?

Thanks very much.