> I was wondering if anyone knew of any good printing shops
> that I could get film transparencies from for cheap masks.
> I'm looking for any places with at least 5000dpi laser
> printers. Thanks much.

Printed circuit board manufacturers use a photolithographic process to make
masks on mylar sheets. Typically this process gives minimum feature sizes in
the range of 1 mil (25.4 ?m). However, runout over 4 to 6 inches can be as
high as 1 mil, so you have to be careful if you have a multi-mask process.

The advantage of this process over a laser printer is that it yields very
dark patterns and the accuracy is quite good. It could be that very high
resolution laser printers exist that will also do a good job.

The order of magnitude for a printed circuit board mylar mask is around
US$100. Usually Gerber files are preferred. But some places will also accept
DXF files and do the conversion for an extra fee. Most circuit board houses
don't know what a GDS file is.

Bill Eaton, Ph.D.
Tunable Filter Product Manager
Chromux - Next Generation DWDM solutions and Wafer Fab Services