# PCBA processing general component inductance introduction

Any component that produces self-inductance is called an inductor. Typically, an inductor consists of a coil and is therefore also referred to as an inductor. It is represented by the letter "L", the basic unit is Henry "H", and the common unit is mH, μH, and the like. Like a capacitor, an inductor is also an energy storage component that has the functions of coupling, filtering, blocking, compensating, tuning, etc. in the circuit.

Inductance classification

According to whether the inductance changes, it can be divided into: fixed inductance, fine-tuning inductance, variable inductance and so on.

According to the magnetic permeability, it can be divided into: air-core coil, magnetic core coil, copper core coil and the like.

According to the purpose, it can be divided into: antenna coil, choke coil, oscillating coil and the like.

Main performance parameters of the inductor

Nominal inductance

The nominal inductance is the physical quantity that reflects the inductance of the inductor. The amount of inductance is related to the shape, structure and material of the coil. The actual inductance is usually mH, μH.

Quality factor

In an induction coil, the ratio of stored energy to energy consumed is called the quality factor, also known as the Q value, expressed as the ratio of the inductance of the coil (ωL) to the loss resistance (R) of the coil. Increasing the frequency will cause the Q value to drop, which will seriously damage the normal operation of the circuit.

Rated current

The rated current is the maximum current allowed by the inductor, and the rated current is related to the wire diameter of the coil. Home color code inductors typically use a method of printing letters on the body of the inductor to indicate the maximum DC operating current. The letters A, B, C, D and E represent the maximum operating currents of 50 mA, 150 mA, 300 mA, 700 mA and 1600 mA,

respectively.

Distributed capacitance

The distributed capacitance of the inductor is the capacitive effect formed between the coil turns. The function of these capacitors can be considered as the equivalent capacitance in parallel with the coil. At low frequencies, the distributed capacitance has no effect on the operation of the inductor; at high frequencies, the performance of the inductor changes.

DC resistance of the inductor

That is to say, the DC loss resistance R of the inductor can be directly measured by the multimeter's ohmmeter.

Inductance identification method

The identification method of the inductor is similar to the identification method of the resistor and the capacitor, as well as the direct label method, the text symbol method and the color scale method.

Inductance detection method

Inductance performance testing is often combined with visual inspection and multimeter testing. First check the appearance to see if the coil is damaged or burned out (this type of fault is more common). If this is not the case, use a multimeter to test. If the measured resistance of the coil is much larger than the nominal value or tends to infinity, the inductor is turned on; if the measured resistance of the coil is much smaller than the nominal value, it indicates that there is a short circuit fault inside the coil.

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