# Can board withstand 100A?

2023-09-06Archive

The current of a conventional PCB design does not exceed 10A or even 5A. Particularly in consumer and consumer electronics, as a rule, continuous operating current on PCB does not exceed 2A. However, if you want to design power wiring for company's products, continuous current can reach about 80A, then consider instantaneous current and leave a margin for whole system, and continuous current of power wiring must withstand more than 100A.

Then question arises, which printed circuit board will withstand a current of 100 A?

Method 1: PCB layout

To figure out overcurrent capability of a PCB, we will first start with structure of PCB.

Let's take a two-layer printed circuit board as an example. This PCB is usually a three-layer structure: copper cladding, plate and copper cladding.

The copper jacket is path that current and signals take in PCB.

According to knowledge of high school physics, we can know that resistance of an object is related to material, cross-sectional area and length.

Since our current flows through copper sheath, resistivity is fixed. The cross-sectional area can be thought of as thickness of copper sheath, which is thickness of copper in PCB processing option.

Normally, thickness of copper is expressed in ounces, conversion of copper thickness to 1 ounce is 35 microns, to 2 ounces is 70 microns, and so on.

Then it can be easily deduced that when a large current must be passed through PCB, wiring should be short and thick, and thicker thickness of copper on PCB, better.

Actually, there is no rigid standard in technology for length of wiring. Commonly used engineering: copper thickness / temperature rise / wire diameter, these three measures measure current carrying capacity of a PCB.

The following two tables can be referenced:

The table shows that a PCB with 1 ounce copper can carry 4.5 amps of current through 100 mil (2.5 mm) wire at 10°C temperature rise.

At same time, as width increases, current-carrying capacity of printed circuit board does not increase strictly linearly, but range of increase gradually decreases, which also corresponds to real engineering situation.

If temperature rise increases, current carrying capacity of wire can also be increased.

Using these two tables, following PCB layout experience can be obtained: Increasing copper thickness, increasing wire diameter, and improving heat dissipation of PCB can improve conductive capacity of PCB.

If you want to use 100A current, you can choose 4 oz copper thickness, set wiring width to 15mm, double-sided wiring, and add a heatsink to reduce PCB temperature rise and improve stability. .

In addition to PCB wiring, wiring can also be used The line is routed as a column. Attach some 100A terminals, such as surface mount nuts, PCB terminals, copper standoffs, etc., to PCB or product body. Then connect 100A wire to copper lug type terminal. . Thus, large currents can pass through wires.

Method 3: Setting up copper strips

Even copper rods can be customized.

The use of copper bars to carry high currents is a common practice in industry, such as transformers, server cabinets, and other applications where copper bars are used to carry large currents.

Attach a table of copper bar current capacity:

Method Four: Special Crafts

In addition, there are some special PCB processing processes, and domestic manufacturers may not find processing.

For example, Infineon has a PCB with a three-layer copper construction. The top and bottom layers are layers of signal wires, and middle layer is a 1.5mm thick copper layer, which is specially used for arrange power supply. This PCB can be easily made for small volume overcurrent of 100A or more .