Why Bob,
It sounds like you have had the unfortunate discomfort of that nasty HV
stuff too... Ah yes, the old one hand in the pocket thing. I do remember it
well. Your words are well taken about the High Altitude part also. I worked
with a customer that needed a light fixture in a large cable drum, (cable
was a mile long LF antenna) and as it turned out they almost didn't need to
power the light. The corona around the fixture was so bad AND bright, the
comment was, "we don't need no ..... power to the light". Anyway, I just
wanted to make these comments that as most of you may have guessed, don't
have a lot to do with the subject, I just had to type something on the
keyboard. :-) <G>
Have a good holiday everyone...
Regards,
Scott Decker
AKA: PadMasterson
Mentor Design Supervisor, Portland
7245 NW Evergreen Pkwy., Suite 100, Hillsboro OR 97124
(503)531-2050 ext. 1820 FAX: (503)531-2051
[log in to unmask] <mailto:[log in to unmask]>
<mailto:[log in to unmask] <mailto:[log in to unmask]> >
Tyco Design
Formerly Praegitzer Design, The Fine Line in Printed Circuits
-----Original Message-----
From: Bob Landman [SMTP:[log in to unmask]]
Sent: Wednesday, December 15, 1999 8:28 AM
To: [log in to unmask]
Subject: Re: [DC] PWB High Voltage Material Choices?
Greg,
One item you need to know is the maximum working altitude. At low
air
pressure, arcing and corona are a serious problem. 30KV is certainly
going to produce corona if there are any sharp points. Conformal
coatings help - make sure the material can withstand the HV and
ozone
production without degrading significantly.
You have to assume that dirt is attracted to the board due to static
field effects. The conformal coating makes sure that the dirt can't
short out the board. Look inside any TV monitor and you will see
that
they are filthy after a few months of operation but they keep on
working. That's good design. Also, assume that this dirt reduces
heat being shed by the parts (forced or natural convection effects
are
reduced as dirt is not a good heat conductor.
Just be as conservative in your design as $$$ will allow. (and keep
your fingers away and my favorite rule around HV is that I always
keep
one hand in my pocket at all times [across the chest HV is deadly
stuff!)
Bob
----- Original Message -----
From: Greg Kaskey <[log in to unmask]>
To: <[log in to unmask]>
Sent: December 15, 1999 10:07 AM
Subject: [DC] PWB High Voltage Material Choices?
All,
I hope you are doing well.
What PWB Material do I call out for one that is 0.074 inch thick and
it does
High Voltage Multiplying with 30K Volt Output?
The board has no solder mask and is encapsulated in a "Black, Rubber
Like
Material". Also, the Board looks like it has some kind of clear
coating that
does not remind me of a "normal" protective coating which is applied
to the
entire finished assembly; it is soft vs. hard and can be easily
scraped off.
What questions would I need to ask to determine some of the material
choices?
Thanks for Helping,
Greg Kaskey
Sector Electronics, Inc.
V: 770-955-8044
E: [log in to unmask]
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