COPPER
COPPER
The next layer is a thin copper foil, which is laminated to the board with heat and adhesive. On common, double sided PCBs, copper is applied to both sides of the substrate. In lower cost electronic gadgets the PCB may have copper on only one side.
The copper thickness can vary and is specified by weight, in ounces per square foot. The vast majority of PCBs have 1 ounce of copper per square foot but some PCBs that handle very high power may use 2 or 3 ounce copper. Each ounce per square translates to about 35 micrometers or 1.4 thousandths of an inch of thickness of copper.
The most common unit of measure for the copper thickness on a printed circuit board is ounces (oz). But how thick is that? It’s the resulting thickness when 1 oz of copper is pressed flat and spread evenly over a one square foot area. This equals 1.37 mils (1.37 thousandths of an inch).
1 once = 35 micron = 1.4 mil