Try poly micro technologies.  They sell fused quartz tubes of ID as small
as 1 micron!!

Their internet site is http://www.polymicro.com

we normally drill the holes in glass (though we have not gone as small as
50 microns).  You could check on drill bits from a new jersey based company
called Lunzer.

Shekhar Bhansali

At 03:04 PM 10/6/98 -0400, you wrote:
>I need to etch holes in a glass substrate (lead glass), the thickness of
>which are between 0.5mm and 3.0mm. I was told that I should be able to
>achieve an aspect ratio (hole diameter to substrate thickness) of about
>100:1. I am looking for through-hole sizes about 50 microns in diameter (at
>least on the surface). Etching could be carried out from both sides of the
>glass. Can anybody please offer me any information on the correct acids
>(solvents for lead glass only), temperatures, times etc,etc,etc.....
>
>Also, does anybody know where I might be able to procure glass capilliary
>tubes with inside diameters in the range of 20microns!)
>
>All information would be gratefully recieved!
>
>                       Karl Cazzini
>
>
>
>email:         [email protected]
>
>
>
>
>