(from the same Dan Lancaster of the CMOS Cookbook... another great piece that if needed I can link)
From an article:
Enjoy!Back in the late 1950’s, it was
conclusively seen that potting your
circuits in epoxy in no manner offers
any design secrecy whatsoever. In
fact, epoxy potting will always have
the exact opposite effect.
First, any reasonably good design
engineer could select a "black box"
approach and carefully look at the
inputs and the outputs of the circuit.
From the circuit’s size, cost, and from
being aware of trade journals, data
books, distributor’s catalogs, and ap
notes, they can easily come up with
three or four methods to provide the
same function.
At least one of which will end up
far cheaper, better, and more creative
than yours.
Juanro
EDIT: To be fair, source: http://www.tinaja.com/hack01.shtml (I found it _after_ I found the direct link to the pdfs via google...)