A diffusion barrier, e.g. a copper layer (e.g. in a trimet strip), can be used.

FR-4 copper-clad sheets are fabricated with circuitry etched into copper layers to produce printed circuit boards.

The de-smear process ensures that a good connection is made to the copper layers when the hole is plated through.

This layer is analogous to the copper layer(s) of a printed circuit board (PCB).

The substrate is attached to a heat spreader by soldering the bottom copper layer to it.

Both pennies had only the layer of copper layer left after a week.

The envelope was stainless steel, with an inner copper layer for compatibility.

The kris bears scenes from the Ramayana on an unusual thin copper layer which partially covers it.

When the copper layer on the mold grows to the desired thickness, the electrical current is stopped.

For hobbyists and amateurs who mostly use only the bottom copper layer, this can be easily set.