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

However, some products are designed for power wiring, and the continuous current can reach about 80A. Considering the instantaneous current and leaving a margin for the entire system, the continuous current of the power wiring should be able to withstand more than 100A.

Then the question is, what kind of PCB can withstand a current of 100A?

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.

Actually, in 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.