Jack,

As others have indicated, most good FR4s will handle going down there just fine.  In a prior life back in Minneapolis, we took product down to -65°C to stress test it and the board was never the problem (parts on the other hand.....).  If you going for a wide range say -40°C to +80°C on a routine basis, spec a better FR4 material. 

One other thing you have to watch out for is that clock rates/edge-rates/timing can get a little faster when one goes colder and slower when you get hotter.  So something that works at 0°C or even -20°C may not handle -40°C.  Components can also not handle those temps, so a good review needs to be done.

Best,

-Jeffrey

Jeffrey A. Jenkins
Sr. PCB Staff Designer, CID+/CIT
L-3 Communications, Linkabit Division
Work:  858-552-9832
Email:  [log in to unmask]



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Wednesday, June 01, 2016 10:36 AM
To: [log in to unmask]
Subject: [TN] FR4 in COLD environments

Has anyone ever heard anything about the reliability of circuit boards in cold environments?
(continuous -40C)
I couldn't find anything on TechNet or in the Printed Circuits Handbook...

thanks,
Jack


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