What materials are needed for SMT inductors? _ Parameters of SMT inductors

Overview of Chip Inductors
Chip inductors, also known as power inductors, high current inductors, and surface mounted high-power inductors. Featuring miniaturization, high quality, high energy storage, and low resistance.

What materials are needed for SMT inductors?
The materials required for SMT inductors are mainly magnetic cores and copper wires. Because SMT inductors are mainly composed of magnetic cores and copper wires.

The inductance in general electronic circuits is a hollow coil or a coil with a magnetic core, which can only pass a small current and withstand a lower voltage; And power inductors also have hollow coils and magnetic cores, mainly characterized by being wound with thick wires, which can withstand tens, hundreds, thousands, and even tens of thousands of amperes.

Power chip inductors are divided into two types: with and without magnetic covers, mainly composed of magnetic cores and copper wires. It mainly plays a filtering and oscillation role in the circuit.



The commonly used SMT inductors in the current market
1) Ferrite patch inductor

Features: Small volume; Low magnetic leakage; There is no mutual coupling between the pieces, and the reliability is high; No leads, no traceability, suitable for high-density surface mounting; Excellent weldability and heat resistance, suitable for wave soldering and reflow soldering.

2) Wound surface mount inductor

Features: Small size, suitable for high-density surface mounting; Adopting an end electrode structure effectively suppresses parasitic component effects caused by leads; Better frequency characteristics and stronger anti-interference ability; Excellent weldability and heat resistance to impact; High application frequency, high generation accuracy, and good consistency.

3) Ceramic stacked chip inductor

Features: Aluminum oxide ceramics, suitable for high self resonant frequencies; Small size (1.6t0.8t0.8mm); At high frequencies, the Q value is high and the inductance value is stable; Temperature range for use: -30 ℃~+85 ℃. Generally used for filtering and oscillation effects.

4) SMT inductor magnetic beads

Features: Suitable for surface mounting; The shape, size, and electrical performance comply with EIA standards; Has good weldability and thermal shock resistance; Suitable for peak and reflow soldering.



Parameters of SMT inductors
1. Inductance

The magnitude of inductance mainly depends on the number of turns of the inductor coil, the winding method, the presence or absence of a magnetic core, and the material of the magnetic core. Usually, the more coils there are, the denser the wound coils, and the greater the inductance. A coil with a magnetic core has a greater inductance than a coil without a magnetic core. The higher the permeability of the magnetic core, the greater the inductance. So there are many factors that determine the magnitude of inductance. The basic unit of inductance is Henry (abbreviated as Hen), represented by the letter "H". The commonly used units are milliHeng (mH) and microHeng (μ H), and their relationship is: 1H=1000mH; 1mH=1000 μ H

2. Permissible deviation

The allowable error value between the annotated sensitivity and the actual sensitivity. The SMT inductors commonly used in oscillation or filtering circuits require high accuracy, with an allowable deviation of ± 0.2% to ± 0.5%; The accuracy requirement for coupling or high-frequency resistance current is not high, with an allowable deviation of ± 10%~15%.

3. Distributed capacitance

The capacitance between turns of a coil and between coils and magnetic cores. The smaller the distributed capacitance, the better its stability.

4. Rated current

The maximum allowable current value for SMT inductors to pass through during normal operation. If the working current exceeds the rated current, it will burn out.

5. Quality factor

Also known as Q value or optimal value, it is the main parameter for measuring the quality of inductors. He refers to the ratio of the inductance presented by the chip inductor to its equivalent loss resistance when operating at a certain frequency of AC voltage. The higher the Q value, the smaller the loss and the higher the efficiency.