Homebrew PCBs

We're way off topic, but I'll finish this off by explaining the
(mostly) complete reason why the use of aluminum house wiring failed
in the US.

Aluminum has a different (larger) expansion due to temp than copper
does. With the correct fixtures, it is fine and works for a long time.

However, all existing installations and existing wall sockets use
connectors with the alloy's coefficient of expansion matched to
copper. So some people were using cheaper outlets meant for copper
when they replaced or added an outlet in new construction that had all
aluminum wire. This resulted in the cycle of oxidation and heat and
subsequent fire mentioned.

Add to that, you need to size up aluminum wire a bit for the same
current as compared to copper, and people did not understand or didn't
believe it, so that would cause problems. 

Aluminum wire is perfectly safe when -all- the fixtures, outlets,
wirenuts, etc. used are made for aluminum wire. Unfortunatly a small
percentage of electricians and a large percentage of homeowners didn't
understand and mixed copper with aluminum, sometimes buying aluminum
wire to replace existing copper without swapping out the outlets and
light fixtures.

The connections made to the aluminum wire where it comes in your house
are made specifically for aluminum wire. The pressure cuts through the
oxide and makes what is called a gas-tight seal, so no further
oxidization occurs and the metals don't experience galvanic corrosion.

There, back to PCBs. ;')

Oh, yeah, current USA "copper" pennies are copper plated zinc.

Steve