Doug,
You might consider looking into use of an autoclave. Autoclave testing will
separate the wheat from the chaff within hours as far as CC integrity.
JESD22-A102 has test conditions ranging from 24-336hrs at 121°C, 15 psig
Most polymers will 'discombobulate' within the first 24 hrs [96 hrs is
somewhat difficult to get to]. It is a brutal test!
You will pick up differences between materials [depending on test duration]
within hours, but one is still left to justify the correlation between
'steamy hot' and 'clammy cold'.
I keep an autoclave in the basement for those 'special occasions'!
Steve C
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Friday, February 10, 2012 4:42 PM
To: [log in to unmask]
Subject: [TN] Conf Coating in Cold and Clammy
Good afternoon all,
Recognizing that asking a question of this group late on a Friday
afternoon is questionable judgement on my part, I will give it a shot
anyway.
I am in the midst of the most perplexing material investigation of my
life. Provided I do not get shot, hung or tarred/feathered, I will have
some neat stuff to publish in the next few years. I have a general
question on testing coatings, other than what you might do in aerospace.
Most temperature-humidity tests done on conformal coating are of the
cyclical variety, 25C to 65C, 90% RH for a week. This one is found in
MIL-I-46058 and IPC-CC-830 and is used for material qualification. Nothing
unusual there.
There are cyclical temperature-humidity test that are done as part of
product qualification, such as DO-160E or MIL-STD-883. But these are also
of the cyclical variety and 25C to 65C is common there as well. Nothing
unusual there.
How would one simulate a coated assembly, stored in a cold and clammy
environment (40-50F, 85-100% RH with probable dew points each day) for
months at a time, then powered up?
Are there any tests done in your industry that tests a coatings resistance
to a prolonged cold and clammy conditions? Ideally with some form of
acceleration factor? I know that the automotive industry has something
called a "damp heat" kind of test, but have no experience with that.
I know I can program my humidity chamber for an environment, but don't
really have time to let it sit 3-6 months. It has been suggested that I
jump in my time machine and go back 6 months and I would be done by now,
but my flux capacitor went through our Kyzen cleaning process and has no
flux left. I blame Hillman.
So, any thoughts would be appreciated.
Doug Pauls
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