On Jan 21, 5:32*am, Phil Hobbs
wrote:
I have a partly-baked idea for improving temperature controllers, but it
requires a bunch of nickel plated polyimide film--say 3 to 8 mils thick,
with 40 microinches of electroless nickel on it.

I need to pattern it and then solder to it. *Copper is too conductive,
which is a pity, since I already have a roll of polyimide with 1/2 oz Cu
on it.

Could you do electro-etching to thin the copper down until it was
resistive enough? You would need to get down from 12.5 micron of
copper to about 0.03 micron, which would be tricky - since the copper
isn't going to be a uniform 12.5 micron thick layer to start with,
you'd probably end up with a network of isolated islands if you tried
to do it in one hit.

Alternating electro-erosion and electro-polishing might work.

I've been in situations where even a single-atom thick layer of metal
was too conductive for my purposes, but 40 microinches/ 1 micron of
nickel would be a good deal more conductive than that.

--
Bill Sloman, Nijmegen