Any body able to help out?

-----Original Message-----
From: Healey, Brett 
Sent: Wednesday, May 05, 2004 6:10 PM
To: Fern Abrams
Subject: Recommendations

Hi Fern,
I have a quick question and hope either you can answer it or know of
someone who can.  In a typical electronics lab, the humidity level
should be between 30% and 70% and if the level goes outside this range,
all operations must stop.  This something that most, if not all,
electronic labs adhere to.  I need to know what the recommendations are
for a thermal chamber.  In the past we used small Thermal-Vacuum
Chambers. (TVAC)  In such, the humidity is of no concern since there
isn't any air present.  But we are currently using a simple thermal
chamber to heat and cool cycle our spaceflight circuit boards.  We have
a dry air purge that we feed into the chamber to regulate the dew point
so that moisture doesn't collect on the circuit board.  Someone years
ago pulled an arbitrary number out of a hat as to the dew point level
needed to start the test and that level has no rhyme or reason at all.
In fact, at room temperature, the dew point we use would force the
chamber to a 2% humidity level.  The question I have is: since
electronics labs must adhere to the 30% to 70% humidity level, wouldn't
that also apply to the thermal chamber operation?  In other words,
should we adjust the dry air purge such that we maintain a 35% RH level
while thermal cycling our flight boards?  We would like to do what is
recommended by IPC to insure our boards are not at risk from static
conditions so I would like your recommendation on this matter.

Thank you

Brett Healey
Sr. Engineering Technician
[log in to unmask]

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