James,
Good advise on the conformal coating.
May I ask, what thickness to you specify
for that type of voltage, or better yet,
how many mils of mask min. per 100V.
I know many board shops don't get it evenly
so I'm looking for a good value that accounts
for such a thing.
I've got several emails concerning the validity
of mask and that it isn't recognized as an
insulator by..... UL I think....
What (IF anyone knows well) other alternatives
to mask or variations of mask that are recognized
globally as insulators?....
Chris Robertson
[log in to unmask] <mailto:[log in to unmask]>
> Larry,
>
> Basic FR4 will take 500V per mil theoritically, but in
> practical i have used 500 volts design with 25V per
> mil gap, ie. use 20 mil space and avoid sharp bends in
> the design. strictly provide solder mask and make
> provision for electrostatic shielding. Do not try to
> create a potential difference of 500 v between
> layers(if it is multiu layer) , I prefer DSBs are
> better here. Advice the assembly fabricator to put
> conformal coat on the assembled board.(polymer coat to
> protect the PCB from moisture absorption and protect
> the operators/service engineers/ polymer coat will be
> very good if the card is going to function in high
> humidity environment.).
> Regards
> James M Paul
> PCB Design Engineer.
> ISRO Satellite Centre, Bangalore, INDIA.
>
> --- Randy McHugh <[log in to unmask]> wrote:
> >
> Larry,
> >
> > Some things to consider are:
> > 1.) Thickness/gap of the traces, your conductor
> > width is driven by current, the gap by the voltage.
> > 2.) Filling vias. If you have high current with your
> > voltage you may have to fill large diameter vias
> > with solder.
> > 3.) External covering of the board. Is it just
> > solder mask or are you conformally coating the
> > board?
> > 4.) AC or DC voltage noise. If the high voltage
> > trace is generating alot of noise you will need to
> > shield it.
> > 5.) You shouldn't have to use different substrate
> > unless you want to heat up the trace by using a
> > small width.
> >
> > Good luck,
> > Randy McHugh
> >
> > -- >> Anyone out there have any experience with 500
> > volts on a printed circuit
> > -- >> board? What design considerations have to be
> > considered? Different
> > -- >> board
> > -- >> materials? Looking for some guidance or
> > references.
> >
> > -- >> Larry L. Pucket
> > -- >> [log in to unmask]
> >
> > -- >>
> >
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> > Optimum Design Inc
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