Hello Greg,
I've seen similar (on HV Laser power supplies). They stay charged up for
ages, and bite hard!!
The surface coating was a silicone rubber compound. The black potting
compound is most likely also silicone rubber.
Your board was probably initially coated in the clear before finally being
potted as an assembly in the black.
This stuff has a dielectric strength in the order of 20kV /mm.
I think that ordinary FR4 is ok at that thickness (no internal layers),
your main problem being air discharge on the surface of the board and
component leads, hence the potting compound.

regards,

Phil.

At 10:07 15/12/99 EST, you wrote:
>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]
>
>____________________________________________________________________
>Get free email and a permanent address at http://www.netaddress.com/?N=1
>

Phil Dutton C.I.D.
Senior CAD Technician
IPC Certified Interconnect Designer
Vision Abell Pty Ltd
Second Avenue, Technology Park,
Mawson Lakes.  SOUTH AUSTRALIA  5095
===============================================================
Phone :         (08) 8300 4400 (reception)
Fax :           (08) 8349 7420
email:          [log in to unmask]
Internet Page:  http://www.vsl.com.au
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