Hi,
       I don't know at which speed you have spun the polyimide and ppr.I think
the curing time was not sufficient in ur process.Precure the polyimide at 120
degrees for 30minutes.  Then it will not dissolve in organic solvents like
acetone.
  All the best.

  with regards ,
  D.sheela

Daniela Kögler  wrote:
  Hi,
I also work with the polyimid PI-2574.
I cured the polyimid at 110 degrees 3 minutes and it got etched and
transferred the pattern of a second photoresist layer. Unfortunately the
polyimid lost the adhesion to the si-wafer by the removal of the
photoresist.

I tried to cure the polyimid at 160 degrees; unfortunately it did not get
etched with the photoresist.

Is there a chance to etch the polyimid with photoresist developer AND remove
the photoresist afterwards?