Last revised: January 13, 2025

Chip inductors are manufactured using semiconductor material. General specifications, performance specifications and features are all important parameters to consider when searching for chip inductors.

General Specifications for chip inductors include technology, core material, packing method and applications. The following are technology choices: 

• Solenoidal (standard) core
• Toroidal
• Bobbin core
• Wirewound
• Multilayer
• Laminated

Solenoidal cores are rod-shaped cores. Toroid chip inductors look exactly like doughnuts and come in various diameters, thickness, permeability and types depending upon the frequency range of interest. They have a high inductance for the physical space occupied. A bobbin core is a chip inductor with a core with the shape of a bobbin or spool.  Bobbin cores are available with and without leads and in the axial and radial form.

A wirewound inductor is an inductor with a core made of wound wires. Multilayer inductors are inductors constructed by layering the coil between the layers of core material.  The coil normally consists of a bare metal material (no insulation). This technology is normally referred to as "non-wirewound".

The inductance value can be made larger by adding additional layers for a giving spiral pattern. Laminated chip inductors are ferrite beads with a core that is constructed by stacking multiple laminations on top of each other.  The laminations can be of a variety of materials and thicknesses.

Core Materials and Packing

Coils can be wound on various core materials, the most popular being iron (or iron alloys, laminations, or powder) and ferrite, a black, nonconductive, brittle magnetic material. These are all ploys to multiply the inductance of a given coil by the "permeability" of the core material.

Core Materials

The core may be in the shape of a rod, a toroid (doughnut), or other shapes. Additional core materials include:

• Air
• Ceramic
• Phenolic
• MPP
• Molypermalloy powder

Packing Methods

• Tape reel
• Tray
• Tube
• Bulk pack

Common Applications

• Common mode choke
• General purpose
• High current
• High frequency
• Power inductor
• RF choke

Additional Features

Common features for chip inductors include shielding and molded case. A shielded inductor is designed for its core to contain the majority of its magnetic field. An inductor with a molded case has a case that has been formed via a molding process. 

Common molding processes include injection and transfer molding. Molded inductors typically have well defined body dimensions that consist of smooth surfaces and sharper corners as compared to other case types.

Standards

MIL-I-83446/10 — Inductors, chip, thick film, fixed.

SMD 5962-11017 — Inductors, SMD, chip, thin film, tight tolerance, 0402.

Chip Inductors FAQs

What are the key differences between various core materials used in chip inductors, and how do they affect performance?

The key differences between various core materials used in chip inductors and their effects on performance can be summarized as follows:

Air Core Inductors

Characteristics: Also known as ceramic core inductors, they have a very low thermal coefficient of expansion, which provides high inductance stability. They are non-magnetic, meaning there is no increase in permeability.

Performance Impact: These inductors are stable across temperature variations but do not benefit from increased permeability, which can limit their inductance values compared to magnetic cores.

Ferrite Core Inductors

Characteristics: Made from a crystalline magnetic material composed of iron oxide and other elements, ferrite cores have high electrical resistivity and high magnetic permeability. They are classified into soft and hard ferrite based on magnetic coercivity.

Performance Impact: Ferrite cores are suitable for high-frequency applications due to their high permeability and resistivity, which help reduce eddy current losses.

Iron Core Inductors

Characteristics: These cores offer high power and inductance values but have limited high-frequency capabilities.

Performance Impact: They are ideal for applications requiring compact inductors with high inductance but are less effective at high frequencies due to increased core losses.

Silicon Steel

Characteristics: Silicon steel is a steel alloy with a high saturation point and moderate permeability. Grain-oriented silicon steel can achieve higher inductance levels and reduce the size and weight of inductors.

Performance Impact: It is widely used in low-frequency applications due to its high saturation point, but it is not ideal for high-frequency applications due to core losses.

MPP (Molypermalloy Powder) Cores

Characteristics: MPP cores are known for superior core loss properties and high permeability.

Performance Impact: They are efficient and compact, making them suitable for applications where space and efficiency are critical, although they tend to be more expensive.

High Flux Cores

Characteristics: These cores are advantageous when space and DC bias performance are critical constraints.

Performance Impact: They provide good performance under high DC bias conditions and are suitable for compact designs.

Each core material offers distinct advantages and limitations, influencing factors such as inductance, energy loss, stability, and suitability for specific frequency ranges. The choice of core material should align with the specific requirements of the application, such as frequency, size constraints, and cost considerations.

What is the impact of core shape on inductor performance?

The impact of core shape on inductor performance can be significant, as different shapes can influence the inductor's efficiency, size, and suitability for specific applications. Here are some key points regarding core shapes:

C Cores

Construction: C cores are made by wrapping a continuous strip of thin material and then cutting it into two C-shaped halves.

Performance Impact: The thin material construction helps reduce core losses at high frequencies. The cuts allow for gaps, which can be beneficial in certain applications.

Ferrite and Powdered Cores

Variety of Shapes: These cores are available in various shapes, which can be selected based on the specific inductive requirements of an application.

Performance Impact: Different shapes and materials are generally better suited for high-frequency circuits, allowing for optimized performance in these applications.

E Cores

Design Considerations: E cores, such as those made from Kool Mµ material, offer options for reduced losses and a smaller footprint, although they may have a larger overall height.

Performance Impact: They are often chosen for their cost-effectiveness and efficiency in specific designs, balancing size and performance constraints.

The choice of core shape should align with the application's requirements, such as frequency, space constraints, and cost considerations. Each shape offers distinct advantages that can be leveraged to optimize inductor performance for specific use cases.

What are the advantages of using ferrite cores in high-frequency applications?

The advantages of using ferrite cores in high-frequency applications are primarily due to their material properties, which make them well-suited for such environments. Here are the key benefits:

High Magnetic Permeability

Ferrite cores have high magnetic permeability, which allows them to efficiently store magnetic energy and achieve higher inductance values. This property is particularly beneficial in high-frequency applications where efficient energy transfer is crucial.

High Electrical Resistivity

The high electrical resistivity of ferrite cores helps minimize eddy current losses. Eddy currents are loops of electrical current induced within conductors by a changing magnetic field, and they can cause significant energy losses at high frequencies. Ferrite's resistivity reduces these losses, enhancing overall efficiency.

Variety of Shapes

Ferrite cores are available in various shapes, which can be selected to meet specific inductive requirements. This flexibility allows for optimized performance in high-frequency circuits, as different shapes can influence the inductor's efficiency and size.

Suitability for High-Frequency Circuits

Due to their material properties, ferrite cores are generally much better suited for high-frequency circuits compared to other core materials. This makes them a preferred choice in applications such as RF circuits, power supplies, and signal processing.

These advantages make ferrite cores a popular choice in high-frequency applications, where efficiency, reduced losses, and compact design are critical considerations.

What are the differences between soft and hard ferrite cores?

Soft Ferrite Cores

Magnetic Coercivity: Soft ferrites have low magnetic coercivity, meaning they can be easily magnetized and demagnetized. This property makes them suitable for applications where the magnetic field needs to change rapidly, such as in transformers and inductors used in high-frequency applications.

Applications: Due to their low coercivity and high permeability, soft ferrites are ideal for high-frequency applications, including RF circuits, power supplies, and signal processing.

Hard Ferrite Cores

Magnetic Coercivity: Hard ferrites have high magnetic coercivity, which means they retain their magnetization and are not easily demagnetized. This makes them suitable for permanent magnet applications.

Applications: Hard ferrites are typically used in applications where a permanent magnetic field is required, such as in motors, loudspeakers, and magnetic holding devices.

These distinctions in magnetic properties and applications make soft and hard ferrite cores suitable for different types of engineering applications, depending on the requirements for magnetic field stability and frequency response.

What are the advantages of using hard ferrite cores in permanent magnet applications?

The advantages of using hard ferrite cores in permanent magnet applications are primarily related to their magnetic properties:

High Magnetic Coercivity

Hard ferrite cores have high magnetic coercivity, which means they retain their magnetization and are not easily demagnetized. This property is crucial for permanent magnet applications where a stable and lasting magnetic field is required.

Cost-Effectiveness

Hard ferrites are generally more cost-effective compared to other permanent magnet materials like rare-earth magnets. This makes them an economical choice for applications where cost is a significant consideration.

Corrosion Resistance

Ferrite materials are inherently resistant to corrosion, which enhances their durability and longevity in various environmental conditions.

Thermal Stability

Hard ferrites exhibit good thermal stability, maintaining their magnetic properties over a wide range of temperatures. This makes them suitable for applications that experience temperature fluctuations.

These properties make hard ferrite cores a popular choice in applications such as motors, loudspeakers, and magnetic holding devices, where a permanent magnetic field is essential.

What are the differences between ferrite and rare-earth magnets?

The differences between ferrite and rare-earth magnets can be understood in terms of their material properties, applications, and performance characteristics:

Material Composition

Ferrite Magnets: These are composed of oxides like SrO, BaO, or Fe2O3. They are ceramic magnets known for their low cost and corrosion resistance.

Rare-Earth Magnets: These include materials like samarium-cobalt and neodymium-iron-boron. They are known for their high magnetic strength and are more expensive than ferrite magnets.

Magnetic Properties

Ferrite Magnets: They have lower magnetic strength compared to rare-earth magnets but are cost-effective and have good corrosion resistance.

Rare-Earth Magnets: They exhibit superior magnetic properties, with neodymium magnets being particularly strong. However, they can be prone to oxidation and thermal shock.

Applications

Ferrite Magnets: Due to their low cost and corrosion resistance, they are used in applications where price is a priority, such as in automotive and power tools.

Rare-Earth Magnets: These are used in high-performance applications requiring strong magnetic fields, such as in motors, generators, and aerospace applications.

Thermal and Mechanical Properties

Ferrite Magnets: They have good thermal stability but lower mechanical strength and energy output.

Rare-Earth Magnets: Samarium-cobalt magnets have excellent temperature stability and resistance to demagnetization, while neodymium magnets have impressive magnetic properties but less optimal thermal properties.

These distinctions make ferrite and rare-earth magnets suitable for different engineering applications based on cost, magnetic strength, and environmental conditions.

Chip Inductors Media Gallery

References

GlobalSpec—Triad Magnetics: Guide to Inductors

GlobalSpec—Rare Earth Magnets

Image credits: 

API Technologies Corp - Spectrum Control | Coilcraft CPS