I am producing a structure that consists of two SU-8 layers. One
     20microns thick the other 70microns.

     The base substrate is 0.5mm glass with a sputtered copper layer.

     I am producing the two SU-8 layers by spinning, exposing and
     post-baking (90øC hot plate) one and then repeating this for the
     second layer before developing both layer together
     .
     The problem I am having is during the develop stage I get cracking of
     the SU-8 and delamination from the base substrate. (possibly the
     delamination causes the cracking?)

     Does anyone have suggestions as to causes and solutions to this
     problem. Do I need to use a different substrate? Would a different
     post-bake help? All suggestion welcome. (I'll summarise the replies I
     get for list distribution)

     Thanks for your time

     Chris Turner
     Principal Research Engineer
     Central Research Labs
     Dawley Road
     Hayes
     Middlesex
     UK
     UB3 1HH
     tel. +44 (0)181 848 6465
     fax. +44 (0)181 848 6442
     e:mail [email protected]