Dom Bragge asked:

>Using 1.6mm FR4 with LPISM, we need information on how to prevent
>breakdown between tracks on the outside layer separated by 12thou,
>when subjected to 1500V continuously.  What sort of coatings/processes
>aid this?

I'd sure want a big fire extinguisher handy!

You'd want the board scrupulously cleaned, then have something like
Parylene conformal coating applied post assembly - something thicker and
with a higher dielectric than a normal solder mask. Thin coatings like SM
are not really occlusive enough to prevent moisture penetration in even
fairly benign environments. That's a bunch of EMF and a pretty small gap.
You must be talking about a tiny current?

You could consider using a laminate other than FR-4, again - the best
possible dielectric rating. FR4 works real nice at about 5 V.

(warning, the above opinion might be disclaimed instantly, and can only be
offered in a highly secret environment like TechNet)

Let's hope you get a better suggestion...


73,

Jerry Cupples
KC5SXA


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