The usual PCB design current does not exceed 10 A, or even 5 A. Especially in household and consumer electronics, usually the continuous working current on the PCB does not exceed 2 A

Method 1: Layout on PCB

To figure out the over-current capability of the PCB, we first start with the PCB structure. Take a double-layer PCB as an example. This kind of circuit board usually has a three-layer structure: copper skin, plate, and copper skin. The copper skin is the path through which the current and signal in the PCB pass. According to the knowledge of middle school physics, we can know that the resistance of an object is related to the material, cross-sectional area, and length. Since our current runs on the copper skin, the resistivity is fixed. The cross-sectional area can be regarded as the thickness of the copper skin, which is the copper thickness in the PCB processing options. Usually copper thickness is expressed in OZ, the copper thickness of 1 OZ is 35 um, 2 OZ is 70 um, and so on. Then it can be easily concluded that when a large current is to be passed on the PCB, the wiring should be short and thick, and the thicker the copper thickness of the PCB, the better.

In actual engineering, there is no strict standard for the length of wiring. Usually used in engineering: copper thickness / temperature rise / wire diameter, these three indicators to measure the current carrying capacity of the PCB board.

PCB wiring experience is: increasing the copper thickness, widening the wire diameter, and improving the heat dissipation of the PCB can enhance the current-carrying capacity of the PCB.

So if I want to run a current of 100 A, I can choose a copper thickness of 4 OZ, set the trace width to 15 mm, double-sided traces, and add a heat sink to reduce the temperature rise of the PCB and improve stability.

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Method two: terminal

In addition to wiring on the PCB, wiring posts can also be used.

Fix several terminals that can withstand 100 A on the PCB or product shell, such as surface mount nuts, PCB terminals, copper columns, etc. Then use terminals such as copper lugs to connect wires that can withstand 100 A to the terminals. In this way, large currents can pass through the wires.

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Method three: custom copper busbar

Even copper bars can be customized. It is a common practice in the industry to use copper bars to carry large currents. For example, transformers, server cabinets and other applications use copper bars to carry large currents.

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Method 4: Special process

In addition, there are some more special PCB processes, and you may not be able to find a manufacturer in China. Infineon has a kind of PCB with a 3-layer copper layer design. The top and bottom layers are signal wiring layers, and the middle layer is a copper layer with a thickness of 1.5 mm, which is specially used to arrange power. This kind of PCB can easily be small in size. Flow above 100 A.