1 -- no
2 -- yes; you can even calculate the change in RH.
3 -- no
What it means to your board is that the probability of condensation is less
because the RH is lower. HOWEVER, when you power that product up in that
same room, the RH at the board location (and the opportunity for
condensation) are the same as in the rest of the room.
And things can get really exiting when you take that same product out of
your car, which was parked in your very cold or freezing driveway and bring
it in a nice warm, high RH, room or office. In all cases the amount of water
near the board is about the same, but the likelyhood of condensation varies
greatly (but if you are wearing glasses, you already knew this, because
those things fog up some times).

Have fun,
Ahne.
A-Laser, Inc
(5403)641-9428

Oh, by the way, the actual occurence of condensation and the subsequent
collection of dirt on your board (the dirt will hurt after some time) will
occur where you have the highest voltages says Murphy (otherwise you would
not get the most amount of damage).
Personally I believe the dirt and subsequent damage occurs at the highest
voltage gradient.

More fun.
A.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Craig Hillman
Sent: Thursday, July 22, 1999 3:00 AM
To: [log in to unmask]
Subject: [TN] Humidity Measurement


An environmental question:

        I have a board operating in a 30C, 70%RH environment. The board
is operating at 85C. How do I determine the humidity level at the
board?

        1. Is the moisture concentration and the RH lower than ambient
because of evaporation?
        2. Is the moisture concentration the same and the RH lower because
of a higher temperature (and thus higher solubility limit)?
        3. Is the moisture concentration and the RH higher than ambient
because the higher temperature results in a higher solubility limit?

Thanks in advance,
Craig

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