Hello,

The following is the summary:

1.  It is called a dry film photoresist
2.  Used mainly in pc circuit board industry/flat pannel displays
3.  37-75 microns thick:  depends on exact type
4.  I have only found a negative version
5.  Applied by:  Lamination(applied pressure and heat), UV exposure,
        aqueous developement solution
6.  Resolution is large (nothing less than 100um)
7.      Known Suppliers(there could be others):
        LeaRonal {http://www.learonal.com} - someone thought the name was
                "Ordyl Alpha"
        Dupont is a supplier {http://www.dupont.com} - RISTON {EM100 or
                4700 series}
        Morton {http://www.morton.com} - Laminar

References:
V.L Spiering and al, Planarization and fabrication of bridges across deep
grooves or holes in silicon using a dry film photoresist followed by an etch
back. J.Micromech. Microeng. 1995 5 pp112 114

H.Lorenz and al, Low-cost technology for multilayer electroplated parts
using laminated dry film resist. Sensors and actuators A 53 (1996),
pp.364-368

full characterization in :

H.Lorenz, thèse 1770, (1998) bibliothèque de l'école polytechnique fédérale
de Lausanne (EPFL), Switzerland.

Web Sites:
http://www.thinktink.com
http://www.dupont.com/pcm/riston/index.html
http://www.dupont.com/pcm/techinfo/laminate/optimize.html
http://www.dupont.com/pcm/techinfo/laminate/hotroll.html

Thanks to:
"Hubert Lorenz" 
"Vladimir Kutchoukov" 
Yit-shun Leung Ki 
Dean Neikirk 
Claude Beaulieu
Mac McReynolds 
[email protected] (Charles R. Sullivan)
"Jason Tauscher" 
"Shile"
"Patrick C.P.Cheung" 
Ken Westra 
"Adam Cohen"

-Angela Rasmussen
The George Washington University
The Institute of MEMS and VLSI Technologies