If you don't have to have Pyrex, there is a photo-imagable glass
(Foturan) which can do 20:1 to 40:1 aspect ratio holes.  Corning invented
the product and discontinued it, then Hoya made it for a few years and
stopped.  The only manufacturer at present is Schott Glaswerke.
       The glass is a photo-sensitive, and becomes etchable in HF when
exposed to UV.  By heat treating the glass, it can be converted to a tough
ceramic.  This is a material with tremendous potential to be used in
micromachining.
      The fly in the ointment is the thermal expansion coefficient is
nowhere near Silicon (8.6 ppm/K), so if you need to wafer bond to Silicon
there may be a thermal mismatch issue.

Their US rep is
Craig Wurzel:
Schott Corporation
3 Odell Plaza
Yonkers , NY 10701-1405
914 378-3811 (Direct Line)
914 968-8900
Fax:  914 378-3892
email:  WUZEL@SG300L.ATTMAIL.COM

Regards,
Jon Bernstein


At 10:25 PM 8/13/98 -0400, you wrote:
>Hi folks.
>
>I looking to drill an array of 10umPyrex substrates.
>
>Any takers?
>
>Thanks.
>
>Robert S. Okojie
>rokojie@ford.com
>
>##################################################################### The
>gazelle runs from the lion to live.  The lion hunts the gazelle to live.  To
>live, # # you must eat.  To live you must run.  -------The African chief
>priest.                    #  #
>###################################################################
>
>
Jonathan Bernstein
MEMS Technology Center
Draper Laboratory, MS 37
555 Technology Square
Cambridge, MA 02139

email:  jbernstein@draper.com
(617) 258-2513
Fax:  617-258-4238