Why is the copper foil thickness of the circuit board in PCB production expressed in ounces?
Why is the copper foil thickness of the circuit board in PCB production expressed in ounces?
Guide: OZ is itself a unit of weight, and the conversion formula for ounces and grams (g) is: 1OZ ≈ 28.35g. But in the PCB industry, ounces are used to indicate the thickness of the PCB copper foil.
In the pcb production industry, we often hear the request of a customer, that is, how many ounces of copper thickness to achieve, this is actually produced according to the requirements of the product, then why is the copper foil thickness of the circuit board in PCB production expressed in ounces? The following small series to introduce in detail.
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Oz (OZ) itself is a unit of weight, and the conversion formula for ounces and grams (g) is: 1OZ ≈ 28.35g. But in the PCB industry, ounces are used to indicate PCB thickness.
1 ounce means the thickness of a 1 ounce piece of copper uniformly spread over an area of 1 square foot (FT2), which is the weight per unit area used to represent the average thickness of the copper foil. Expressed by the formula, 1OZ = 28.35g / FT2 (FT2 is square feet, 1 square foot = 0.909290304 square meters), the specific conversion method will be described below.
Why is the copper foil thickness of the circuit board in PCB production expressed in ounces?
First, the density constant of copper and the relevant unit conversion formula are as follows:
The density of copper ρ = 8.9g / cm?
1 cm (cm) = 10 mm (mm)
1 mm (mm) = 1000 μm (um)
1mil≈25.4um
1 FT2≈929.0304cm2
1mil≈25.4um
According to the mass calculation formula m = ρ × V (volume) = ρ × S (area) × t (thickness), the weight of the copper foil divided by the density and area of the copper is the thickness of the copper foil.
As also known from the above, 1OZ = t × 929.0304cm2 × 8.9g / cm3 = 28.35g
Therefore, t=28.35÷929.0304÷8.9cm≈0.0034287cm=34.287um≈34.287÷25.4mil≈1.35mil
It can be seen that the thickness of the 1OZ copper foil is about 35 um or 1.35 mil.
Copper thickness 1.OZ (0.035mm) Copper thickness 1.5OZ (0.05mm) Copper thickness 2.OZ (0.07mm)
These are all English units, which refer to a 1 ounce copper foil tiled to a thickness of 1 square foot, which is about 35um.
Copper foil is used in the PCB industry based on this, 2 ounces, 3 ounces, half ounces, 1/3 ounces, etc.
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