Recently, new energyFPCThe demand has increased significantly. Today, let's discuss the calculation of the current carrying capacity of FPC copper foil together:

1、 The calculation method is as follows:

First, calculate the cross-sectional area of the track. The copper foil thickness of most FPCs is 35um (if unsure, you can ask the FPC manufacturer, 1 ounce is 35um, but in reality, it is less than 35um). Multiplying it by the line width is the cross-sectional area, and be sure to convert it to square millimeters.

There is an empirical value for current density, which is 15-25 amperes per square millimeter. Measure its cross-sectional area to obtain the flow capacity. I=KT0.44A0.75 (K is the correction factor, usually taken as 0.024 for the inner layer and 0.048T for the outer layer of copper-clad wire). The maximum temperature rise is in degrees Celsius (the melting point of copper is 1060 ℃). A is the cross-sectional area of copper-clad wire, measured in square MIL (not millimeters, note square mil.). I is the maximum allowable current, measured in amperes (amp). Generally, 10 mil=0.010 inch=0.254, which can be 1A. 250 MIL=6.35mm, which is 8.3A

2、 Data:

The calculation of FPC current carrying capacity has always lacked authoritative technical methods and formulas, and experienced CAD engineers rely on personal experience to make more accurate judgments. But for beginners in CAD, it cannot be said that they encounter a difficult problem. The current carrying capacity of FPC depends on the following factors: line width, line thickness (copper foil thickness), and allowable temperature rise. As we all know, the wider the FPC wiring, the greater the current carrying capacity. Here, please tell me: assuming that under the same conditions, a 10MIL wire can withstand 1A, how much current can a 50MIL wire withstand? Is it 5A? The answer is naturally negative. Please refer to the following data provided by an international authoritative organization: The unit of line width is Inch (inch=25.4 millimeters) 1 oz. Copper=35 microns thick, 2 oz.=70 microns thick, 1 OZ=0.035mm 1mil= 10-3inch. Trace Carrying Capacity per mil std 275

3、 Experiment

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

The maximum current value should refer to the maximum allowable value under the temperature rise limit, and the melting value is the value at which the temperature rise reaches the melting point of copper. The temperature rise of 50 mil 1oz is 1060 degrees (i.e. the melting point of copper), and the current is 22.8A.

4、 The relationship between copper platinum thickness, line width, and current in FPC design

Before understanding the relationship between copper platinum thickness, line width, and current in FPC design, let's first understand the conversion between the unit of FPC copper coating thickness in ounces, inches, and millimeters: "In many data tables, the copper coating thickness of FPC is often measured in ounces, and its conversion relationship with inches and millimeters is as follows:

1 ounce=0.0014 inches=0.0356 millimeters (mm) ≈ 36 micrometers (um)

2 ounces=0.0028 inches=0.0712 millimeters (mm)≈ 72 micrometers (um)

Ounces are a unit of weight, and the reason why they can be converted to millimeters is because the copper coating thickness of FPC is ounces per square inch“

FPC Design Copper Platinum Thickness, Line Width, and Current Relationship Table

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