Surface mount inductors mainly come in four types: wire-wound, multilayer, woven, and thin-film chip inductors. The most commonly used types are wire-wound and multilayer. The former is a miniaturized version of traditional wire-wound inductors; the latter is manufactured using multilayer printing technology and stacking processes, resulting in a smaller size than wire-wound chip inductors and is a key product in the field of inductive components. Wire-wound inductors are characterized by a wide inductance range (mH~H), high inductance accuracy, low loss (i.e., high Q), high allowable current, strong manufacturing process continuity, simplicity, and low cost. However, their drawback is the limitation in further miniaturization. Wire-wound chip inductors with a ceramic core can maintain stable inductance and a relatively high Q value at such high frequencies, thus occupying a significant position in high-frequency circuits.

TDK's NL series inductors are wire-wound, with an inductance range of 0.01~100uH, 5% accuracy, and high Q value, meeting general requirements. The NLC type is suitable for power supply circuits, with a rated current up to 300mA; the NLV type has a high Q value, is environmentally friendly (recycled plastic), and is interchangeable with NL; the NLFC has magnetic shielding and is suitable for power lines.

Multilayer surface mount inductors

They have good magnetic shielding, high sintering density, and good mechanical strength. However, their drawbacks include a low yield rate, high cost, smaller inductance, and lower Q value. Compared with wire-wound chip inductors, they have several advantages: small size, which facilitates circuit miniaturization; a closed magnetic circuit, which prevents interference with surrounding components and is not affected by adjacent components, facilitating high-density component mounting; an integrated structure, resulting in high reliability; good heat resistance and solderability; and a regular shape suitable for automated surface mount production. TDK's MLK series inductors are small in size, have good solderability, feature magnetic shielding, and utilize a high-density, single-piece structure for high reliability. The MLG series has a low inductance value, uses high-frequency ceramic material, and is suitable for high-frequency circuits. The MLK series operates at 12GHz, features high Q, and low inductance values (1n~22nH) in a thin-film chip package.

It maintains high Q, high precision, high stability, and small size characteristics in the microwave frequency range. Its internal electrodes are concentrated on the same plane, and the concentrated magnetic field distribution ensures that the device parameters do not change significantly after mounting, exhibiting excellent frequency characteristics above 100MHz.

Woven-type chip inductors

Their characteristics include a higher inductance per unit volume at 1MHz compared to other chip inductors, a small size, and ease of mounting on a substrate. They are used as miniature magnetic components for power processing.