23/50 = 10.3 g/m3
5C @ 10.3g/m3 = 151%RH
5/50 = 3.4 g/m3

I've never tried, but it looks like you should be able to measure 5/50 using capacitive elements, however 5/37 = frozen wet bulb.  Frost point at 5/50 is -4.  It is rather unlikely you could produce such a wet & cold environment,  so they probably figure it isn't worth the cost to monitor.

But I have no idea how they performed the sorption studies to come-up with the rules.

Chris

Chris Mahanna
Robisan Lab



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of colin mcvean
Sent: Monday, August 22, 2011 1:52 AM
To: [log in to unmask]
Subject: [TN] Prepreg storage conditions

Dear all,
 
"Simple" question regarding prepreg storage conditions.....
 
IPC4101 states that prepregs has shelf life of 6 months while in condition 1 at <5 Degrees C (41 F) and 3 months while in condition 2 at <23 Degrees C (73F) and <50% Rh.
 
Condition 1 does not clearly state a humidity control.
Does Humidity still have to be less than 50% while under condition 1? or is this a given considering Temperature vs. Humidity relationship
 
rgds
Colin

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