In PCB (Printed Circuit Board) manufacturing, an ounce (OZ) is essentially a unit of weight, which converts to grams (g) roughly as follows: 1 OZ equals approximately 28.35 g. The term 1 OZ refers specifically to the thickness of 1 OZ of copper uniformly covered over an area of 1 square foot (FT2).
The term 1OZ refers specifically to the thickness of copper weighing 1OZ uniformly over an area of 1 square foot (FT2). This is a method of characterizing the average thickness of copper foil by weight per unit area, and is mathematically expressed as 1OZ = 28.35g/ FT2.
Further, we can convert this to length or thickness as follows:
First, we need to know the density constant of copper and the associated unit conversion formula:
The density ρ of copper is 8.9g/cm³
1 centimeter (cm) is equal to 10 millimeters (mm), 1 millimeter (mm) is equal to 1000 microns (um)
1mil is approximately equal to 25.4um
1 FT2 is approximately equal to 929.0304 cm²
Using the mass formula m = ρ x V (volume) = ρ x S (area) x t (thickness), we can derive the thickness of the copper foil: the weight of the copper foil divided by the density of the copper and the area covered gives the thickness of the copper foil.
Based on the previous information, we have 1OZ=t×929.0304cm²×8.9g/ cm³=28.35g/ FT2 (note that FT2 here should be converted to cm² for the calculation, but it is not adjusted here in order to maintain the original formulation).
Therefore, t = 28.35 ÷ 929.0304 ÷ 8.9cm ≈ 0.0034287cm = 34.287um ≈ 34.287 ÷ 25.4mil ≈ 1.35mil.
In summary, the thickness of 1OZ copper foil is approximately 35um or 1.35 mil. similarly, we can derive the following correspondence:
Copper thickness 1OZ (about 0.035mm)
Copper thickness 1.5OZ (about 0.05mm)
Copper thickness 2OZ (approx. 0.07mm)
