George Herold wrote: : On Friday, May 17, 2019 at 12:02:12 PM UTC-4, Use-Author-Suppli...@127.1 wrote: : > George Herold wrote: : > : On Thursday, May 16, 2019 at 10:02:11 AM UTC-4, Use-Author-Suppli...@127.1 wrote: : > : > We currently use 'Mega 400-105' : > : >
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board material : > : > which is a UV resist type with a 50um thick Polyester substrate but it : > : > has been discontinued and we may also be loosing our darkroom at some : > : > stage. : > : > : Can you buy a life time supply? : > I could not find anywhere that still has stocks. Amazon & CPC/Farnell : > both list it but indicate "Currently unavailable" and "No Longer : > Manufactured". Mega's FAQ confirms this and explains why. : > : > : Can you tell us why regular fiberglass pcb's won't work? : > I think the attraction is that being thin it fits easily into confined : > spaces and can be varnished onto curved surfaces such as cryostat : > pumping lines.
: Good enough. I once had similar thoughts and went looking for a board : house that would make proto-type quantities of copper on flex... : Too spendy.
Doing some web browsing on milling machines suggests some are capable of handling 50um or thinner substrates, including the Othermill brand (now Bantam Tools) and Accurate CNCs. I'm guessing the mechanical mills will be significantly cheaper than the laser ones. None of the manufacturers or distributors websites I looked at included prices which is probably an indication of their height!
: Searching for DIY flex pcb I get a bunch of hits. : how about this, :
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: Searching for Pyralux I find more.
Thanks for those pointers. The Pyralux looks interesting as does the AN10 and AN210 thin/flex FR4 board from CIF.
: Is there something wrong with kapton/ polyimide?
No. People here use Kapton tape in cryostats for its wide temperature range stability.
: And how do you stick it : to your pumping lines?
I have not been involved in actually doing Low Temperature work myself for many years now but I believe the usual technique is GE varnish.
: George H.
Tom.
Ps. I've just noticed your email domain. We have one of your earth field NMR spectrometers here!
Pps. The email address in the header is just a spam-trap.
--
Tom Crane, Dept. Physics, Royal Holloway, University of London, Egham Hill,
Egham, Surrey, TW20 0EX, England.
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