Bill,
I think it was Glyptal. It is a red gooey paint. Most commonly used in
HV applications like the back of CRTs.
I used to have a can here, but I think it got tossed with some personel
changes.
Phil
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brooks,Bill
Sent: Monday, November 07, 2005 1:48 PM
To: [log in to unmask]
Subject: Re: [TN] High voltage breakdown... solutions?
Thanks Phil.
The oil was thought of... although not a specific type.
The routed gap idea was thought of too... and also high insulation
resistance conformal coating...
The corona ball idea is an interesting method... fixing 'sharp points'
in
the process... Of course a redesign of the old board is the appropriate
method...
Didn't Dupont or some other company have a 'corona coating' of some sort
back in the bad old days? I think they had some sort of shellac or
something
they sold for high voltage applications to deal with things like this...
I just can't remember where I saw it...
Bill Brooks - KG6VVP
PCB Design Engineer, C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
Datron World Communications, Inc.
_______________________________________
San Diego Chapter of the IPC Designers Council
Communications Officer, Web Manager
http://dcchapters.ipc.org/SanDiego/
http://pcbwizards.com
-----Original Message-----
From: Phil Nutting [mailto:[log in to unmask]]
Sent: Monday, November 07, 2005 9:50 AM
To: TechNet E-Mail Forum; Brooks,Bill
Subject: RE: [TN] High voltage breakdown... solutions?
Bill,
This is a constant problem that we solved by routing a slot between the
two traces. The slot or gap needs to be sufficient enough to prevent
flash over in air. That assumes your board is in air. You could also
"sink" the board in a dielectric oil or Sulfurhexaflouride, but these
bring new issues to the product.
Another quick solution would be to hand solder a high voltage "corona
ball" along the edge of the etch patterns. Consider the etched edge of
a trace. It is a huge sharp edge. Now if you were to add a blob of
solder to make the edge less sharp you may be able to fix your problem.
Keep in mind there are two issues here, surface tracking and an arc in
air. With surface tracking the routed slot works best.
Hope this is of some help.
Phil
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brooks,Bill
Sent: Monday, November 07, 2005 12:39 PM
To: [log in to unmask]
Subject: [TN] High voltage breakdown... solutions?
It's Monday... had your coffee yet?
I'm trying to gather together some potential solutions to High Voltage
breaking over and arcing between traces on board. The things I know
contribute to this are things like, too little spacing between traces on
the
surface or in the inner layers, sharp points on traces, board
cleanliness or
the presence of contaminants between the potential voltages.
It was suggested that conformal coating the boards after a real good
cleaning might improve the insulation resistance between traces, has
anyone
done this successfully? Do you have any other ideas short of a re-layout
of
the board that could perhaps repair a problem like this?
Any ideas are most appreciated.
Bill Brooks - KG6VVP
PCB Design Engineer, C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
Datron World Communications, Inc.
_______________________________________
San Diego Chapter of the IPC Designers Council
Communications Officer, Web Manager
http://dcchapters.ipc.org/SanDiego/
http://pcbwizards.com
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