there seems no uniformity of units….resistivity surely has units of Ohm.Metres?/QUOTE]
There's a great A D or LT app note that explains, amongst other things, how to use pcb copper as sensing resistor, and the formula is basically that copper-clad squares on an e.g. 1oz pcb that are respectively n and 10n size/dimensions will have the same resistivity.
This article explains it:
Counting squares: A method to quickly estimate PWB trace resistance
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Nice quote from article:
"We now know, for example, that a square of ½ oz. copper has a resistance of about 1 mΩ. This is regardless of the size of the square."
I think that may be why the nylon standoffs say ohms/sq.