How to deal with inductance in PCB design

2025-01-13

Inductors are very common components in electronic circuits. Inductors can be divided into different types according to different classification methods. They have their own unique functions and characteristics in different application scenarios.

First of all, the composition of inductors is mainly composed of two parts: windings and magnetic cores, including:

1. Winding: It is composed of a conductor coil wound on a magnetic core, usually made of copper wire or aluminum wire. The cross-sectional area and number of turns of the wire determine the size of the inductance. The winding can be single-layer or multi-layer winding, or parallel or cross-wire winding.

2. Magnetic core: It can be made of a variety of materials such as hollow tubes, solid magnetic materials or magnetic powders. The material of the magnetic core will affect the performance of the inductor and participate in the transmission of the magnetic field. The main function is to increase the magnetic flux of the inductor.

It is worth noting that the internal structure of the inductor will vary depending on the specific application scenario and manufacturing process. For example, the magnetic core of the iron core inductor is composed of materials such as iron, nickel, iron oxide, etc. There are also various types of micro inductors, SMD inductors, etc., and their structures are also different.

In addition, some inductors will be equipped with auxiliary components such as anti-shake capacitors and winding protection covers to improve circuit efficiency and protect the structure of the inductor.

This time, let's talk about the use of power inductors, one of the most common inductors, and how to deal with them in our PCB design. First of all, power inductors can be divided into shielded inductors and non-shielded inductors. The biggest difference between the two is that one can see the wound coil, and the other cannot be seen because it is covered by a metal shield. Power inductors are mainly used in power electronic equipment, usually one of the core components of AC/DC converters, DC/DC converters, filter networks, stabilized power supplies and other circuits. The functions and effects of power inductors are as follows:

1. Filtering: The power inductor gives the load circuit an impedance to separate high-frequency and low-frequency signals. Filter inductors are mainly used to stabilize the output waveform of the power supply and filter the power supply to reduce the ripple and pulsation of the power supply.

2. Transient response: The power inductor can perform transient response and transition control on the current in the power supply, prevent instantaneous overcurrent and current pulses in the power supply, and improve the stability of the system.

3. Energy storage: In power electronic devices such as AC/DC converters and DC/DC converters, power inductors store energy and convert it into electric fields to provide higher current or voltage in a short time.

4. Isolation: Power inductors can provide an isolation means to isolate the input power supply from the output part, reduce the mutual electrical interference and noise of the cylinder, etc.

In summary, power inductors are one of the key components in power electronic devices. They play a very important role in many applications and can effectively solve problems such as ripple and current overload in the circuit.

When we are designing PCBs, there is a magnetic field generated during the work of inductors, which will change over time. If the intensity of this magnetic field is large enough, it will interfere with the surrounding electronic devices. This interference may cause problems such as circuit performance degradation and signal interference.

In order to reduce the interference of inductors to surrounding electronic devices, some copper skin is usually dug around the inductor. This is because the magnetic field generated by the inductor is conducted to the surrounding electronic devices through the copper skin. If we dig out the copper skin, we can reduce the radiation range of the magnetic field, thereby reducing the impact of EMI.

In addition to digging out the copper foil, other measures can be taken to reduce the interference of the inductor to the surrounding electronic equipment. For example, they can place a shielding cover around the inductor to further reduce the radiation range of the magnetic field. In addition, low-noise power supply, ground wire and other technologies can be used to reduce the impact of EMI.

In short, EMI is a very important issue in PCB design. Inductors are a common electronic component that generates a magnetic field, which may interfere with surrounding electronic equipment. In order to reduce this interference, some copper foil is usually dug out around the inductor, and other measures are taken to reduce the impact of EMI. These measures can help us design a more stable and reliable circuit system.

Of course, the impact of inductance on the circuit is not just these. If the copper foil is not dug out, an eddy current will be generated between the inductor magnetic field and the copper foil, which will cause the inductor area to heat up and the inductance of the inductor to decrease. When we encounter a PCB with a shielding cover, we also need to pay attention to the treatment of the inductor area. Usually, a hole is dug in the shielding cover area above the power inductor to avoid the generation of eddy current phenomenon.

We have learned so much above, so in fact, we only need to pay more attention to the layout of the inductor area and the treatment of the copper foil in PCB design. Reasonable circuit layout can help us reduce the impact of EMI. Or we can also use shielded inductors. Shielded inductors can limit the magnetic flux lines within the shielding cover due to the shielding cover, thereby reducing the impact on surrounding components. The disadvantage is that it is more expensive, so we usually need to consider it comprehensively.

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