Hello Sh. Farhangfar,

I have been following all the recent discussions on wet-etching of
polyimides.  As polyimide is a broad catagory of materials, I am not
sure just what you were looking for.

If you have a specific polyimide that you are using, please identify it.
 There may be a etch procedure for it.

If you need a polyimide that is etchable in positive photoresist
developer (i.e. TMAH solution) and compatible with photoresist, Brewer
Science has a number of materials.  They fall into three categories,
anti-reflective coatings, passivation layers and lift-off/sacrifical
layers.  Our anti-reflective coatings are thin (< 200nm) and have a bake
window of 160 to 180 degrees Celsius.  Passivation layers are from 0.1
to 6 microns in thickness with a bake window of 140 to 180C.  Finally,
PiRL III as a lift-off/sacrifical material ranges in thickness from 1 to
10 microns with a bake window of 200 to 350+C.

The bake windows  determine the etch  properties.  If you bake lower
than the bottom temperature, the layer will wash off in the developer.
 If you bake above the upper number, the material will not etch. Inside
the window the etch rate decreases as bake temperature/time increase.

If you have any questions please contact me.  You can also check out the
Brewer Science website at http://www.brewerscience.com

Best wishes,

Mac Daily