PCB News - The copper thickness stated by the circuit board factory is ounces

The copper thickness stated by the circuit board factory is ounces

Shenzhen iPCB is a high-tech manufacturing enterprise focusing on the development and production of high-precision PCBs. iPCB is happy to be your business partner. Our business goal is to become the most professional prototyping PCB manufacturer in the world. Mainly focus on microwave high frequency PCB, high frequency mixed pressure, ultra-high multi-layer IC testing, from 1+ to 6+ HDI, Anylayer HDI, IC Substrate, IC test board, rigid flexible PCB, ordinary multi-layer FR4 PCB, etc. Products are widely used in industry 4.0, communications, industrial control, digital, power, computers, automobiles, medical, aerospace, instrumentation, Internet of Things and other fields. Here is a small editor to understand with you why ounce is a unit of weight, and why is it used to indicate thickness in Shenzhen PCB board manufacturers?

The first thing to note is that the ounce (OZ) itself is a unit of weight. The conversion formula for ounces and grams (g) is: 1OZ≈28.35g.

In the PCB circuit board industry, 1OZ means the thickness of copper with a weight of 1OZ evenly spread on an area of 1 square foot (FT2). It uses the weight per unit area to express the average thickness of the copper foil. Expressed by the formula, 1OZ=28.35g/FT2 (FT2 is square feet, 1 square foot=0.09290304 square meters).

Specifically, it can also be said that the conversion method of PCB circuit board thickness is as follows:

First of all, we know that the density constant of copper and the conversion formula of related units are as follows:

The density of copper ρ=8.9g/cm3

1 centimeter (cm) = 10 millimeters (mm); 1 millimeter (mm) = 1000 microns (um)

1mil≈25.4um

1FT2≈929.0304cm2

1mil≈25.4um

According to the mass calculation formula m=ρ*V (volume)=ρ*S (area)*t (thickness), knowing that the weight of the copper foil divided by the density and area of the copper is the thickness of the copper foil!

As we know from the previous article, 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 1OZ copper foil is about 35um or 1.35mil.

Copper thickness 1.OZ (0.035mm) Copper thickness 1.5OZ (0.05mm) Copper thickness 2.OZ (0.07mm)

1. The relationship between the line width of the PCB board and the current:

Calculate the cross-sectional area of the track first. The copper foil thickness of most PCB boards is 35um (if you are not sure, you can ask the PCB manufacturer). The cross-sectional area is multiplied by the line width. Pay attention to the conversion to square millimeters. There is an empirical value of current density, which is 15-25 A/mm2. Call it the upper cross-sectional area to get the flow capacity.

2. Data:

The calculation of PCB board current capacity has always lacked authoritative technical methods and formulas. Experienced CAD engineers can make more accurate judgments relying on personal experience. But for CAD novices, it cannot be said that they have encountered a problem.

The current carrying capacity of the PCB board depends on the following factors: line width, line thickness (copper foil thickness), and allowable temperature rise. Everyone knows that the wider the PCB circuit board traces, the greater the current-carrying capacity. Here, please tell me: assuming that under the same conditions, a 10MIL trace can withstand 1A, how much current can a 50MIL trace withstand, is it 5A? The answer is naturally no. Please see the following data from international authorities:

The unit of line width is: Inch (inch inch=25.4millimetres mm) 1oz. Copper=35 microns thick, 2oz.=70 microns thick, 1OZ=0.035mm1mil.=10-3inch.

In the experiment, the voltage drop caused by the wire resistance caused by the wire length must also be considered. The tin on the process welding is only to increase the current capacity, but it is difficult to control the volume of the tin. 1OZ copper, 1mm wide, generally used as a 1-3A ammeter, depending on your cable length and voltage drop requirements.

The maximum current value should refer to the maximum allowable value under the temperature rise limit, and the fuse value is the value at which the temperature rise reaches the melting point of copper. The temperature rise of Eg.50mil1oz is 1060 degrees (that is, the melting point of copper), and the current is 22.8A.