The copper layer thickness in a printed circuit board (PCB) is rated in ounces (also called the copper weight) or in mils (also called the copper thickness.) Both units of measurement are relaying the same information just in a slightly different format. For example, 1 oz. of copper is equivalent to 1 square foot of 1.4 mils (.0014″) thick copper.
Copper weight/thickness is important in several areas of PCB design. The thickness and width of a trace determines the amount of current (amps) the trace can carry. The thickness is also used in the calculation of trace impedance (ohms) in RF and high speed digital circuits.
The following is the formula for cpw (in oz) to thickness (in mils) conversion:
Thickness(in oz) = thickness (in mils) /1.37
The following is the formula for thickness (in mils) to cpw (in oz) conversion:
t ( in mils) = t ( in oz) * 1.37
|1/2 Oz.||.7 mils|
|1 Oz.||1.4 mils|
|2 Oz.||2.8 mils|
Copper Weight / Thickness Chart