Here's what I know about ITO etching.

I used 5%HNO3, 20%HCl, 75%DI water (by volume) at about 60 deg.C. My etch times
varied. I suspect it was a combination of factors, those being: 1. My ITO was
not consistent from piece to piece (I could not batch etch), and 2. The etch
product affects the etchant.

PR (AZ 5124) was OK in the etchant until it started to turn green, then would
rapidly strip off.

This etch process takes a lot of attention. If you can find a more stable
process, you should try that.

Jesse Fowler