Re: PCB's in liquid nitrogen

On May 30, 4:00 am, Robert Baer <robertb...@xxxxxxxxxxxx> wrote:
ggher...@xxxxxxxxx wrote:
Does anyone have experience using printed circuit boards at liquid
nitrogen temperatures?  The best I could find on the web was liquid
nitrogen used for stress testing PCB's.

The boards will be single sided and have either wires or through hole
components attached, resistors and diodes (nothing active).  At the
moment I'm most concerned with having the copper traces peel up from
the substrate.  Would heavier copper help?  (2 oz. or 4 oz.)  I would
hope to use a standard substrate material FR-4, G10....

Thanks,

George Herold

   I had double-sided SMT PCBs made for low temp work (obviously ROHS
*NON* compliant as lead solder holds up at LN temps).
   No problems noted at LN temps, but..the PCB was 30 mil and a vairant
of Geteck (ie: NOT FR-4).
   I would suggest thinner copper and if cannot get Geteck use a Rogers
variant (yeah,i know, more expensive).

Robert, Thanks for the tip on staying with lead based solder. I was
also wondering if thinner traces would work better? Letting the
copper 'move' with the pcb.

I like the bigger traces, because people may be changing components
and the heavier copper will hold up better to resoldering.

George Herold

.

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    (sci.electronics.design)