[HH] Cutting material with a 2-3 micron tolerance

[Brough Turner]

I'm looking for advice and/or useful places to ask for advice.

We have an optically transparent electrically conductive material which we
are using to build antenna arrays and electrical circuits (like Butler
matrices).  It's thin silver conductors in a square mesh on a 112
micrometers thick PET film.  The mesh consists of silver conductors 4.3
micrometers thick and 23.9 micrometers wide. These conductors are arranged
in a square grid with openings that are 301 micrometers in each dimension.
It appears optically transparent because you need a magnifying glass to
even detect the existence of the mesh.

As an example, I'd like to cut out an RF transmission line that is 1.65 mm
wide, i.e. 6 silver conductors and five mesh openings wide - like this,
only with smooth edges:

​
​
You see the problem of course.  As this is carrying 5-6 GHz RF, we need the
conductive edge to be unbroken and straight, and we want to avoid a bunch
of sliced off conductive stubs along the edge.

Reading about laser cutting in Wikipedia suggests it won't be quite good
enough ("positioning accuracy of 10 micrometers and repeatability of 5
micrometers"), but I have no experience here.  At least it would be better
than the PCB machining tool we're currently using.

Can anyone here help?  or suggest where I might go for advice?

Thanks,
Brough Turner

Mobile: +1 617 285-0433   Skype: brough
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