Hi Doug:
> The question is, how do I independently validate the material used, since a
> vendor could theoretically choose whatever they want and stamp it as V-0?
I interpret your question as to how to determine
whether or not a PCB is counterfeit or not.
A UL-certified PCB would have the following markings:
PCB manufacturer's indentification;
manufacturer's grade designation;
UR mark;
flammability rating, e.g., V-0.
So, it is not just a matter of the V-0 mark; all four
marks must be included on the board.
I suppose a vendor could counterfeit all four marks.
If I had a suspect PCB, I would first confirm the PCB
manufacturer and grade designation as being in the UL
"Yellow Book." If they are not in the "Yellow Book,"
then that confirms that the PCB is counterfeit.
If the marks are confirmed by the "Yellow Book," then
the problem of determining a counterfeit is much more
difficult.
Unfortunately, testing the board to V-0 requirements
will not tell you if the board is V-0. The problem
is that the copper traces provide effective heat-sinking
for the board material such that even an HB material
may pass the V-0 test! (I've actually tested an HB
board where the HB material did not extinguish in 10
seconds or 30 seconds, but extinguished in less than
60 seconds!)
The only way to confirm V-0 is to test a board with no
copper. This means you must peel off the copper from
a 1/2-inch by 5-inch section, and then test the section
per UL 94. (You must also remove the solder resist.)
You can't remove the copper and solder resist by
chemical means as this may change the properties of
the board material, and you would not be able to
confirm the flammability rating.
In my experience, I've never had occasion to suspect
a PCB as being counterfeit. We've never bought a
board from a non-UL vendor. While I suppose there
are non-UL vendors, I suspect there are very few.
Good luck!
Best regards,
Rich
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