Dielectric Constant of Advanced Ceramics

The dielectric constant, also known as relative permittivity (εr), is a measure of how well a material can store electrical energy in an electric field. It represents the ratio of a material’s permittivity to the permittivity of vacuum (ε₀). A higher dielectric constant implies greater capacity to store charge, which is critical in capacitors, insulators, and high-frequency electronic components.

Advanced ceramic materials are widely used in high frequency, high power, microwave, radar and packaging fields due to their different dielectric properties. When selecting, companies should evaluate the optimal material combination based on comprehensive factors such as operating frequency, thermal management, mechanical structure and dimensional accuracy.

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Hardness of Ceramics: Properties, Comparison & Applications

Importance of Dielectric Constant in Ceramics

Ceramic materials are widely used in electronics and electrical insulation due to their:

  • High dielectric strength
  • Stable thermal and electrical performance
  • Low dielectric loss
  • Resistance to corrosion and environmental degradation

The dielectric constant plays a pivotal role in RF components, substrates, capacitors, antennas, and semiconductor packaging. Selecting the correct ceramic material with a suitable dielectric constant ensures optimal performance, especially in high-frequency and high-temperature environments.

Factors Affecting the Dielectric Constant of Ceramics

  • Crystal Structure: Materials with polar structures generally exhibit higher εr.
  • Temperature: Dielectric constants can increase or decrease with temperature based on material type.
  • Frequency: At high frequencies, εr often decreases due to reduced dipolar polarization.
  • Porosity: Higher porosity lowers εr due to the presence of air (εr ≈ 1).
  • Grain Size and Density: Finer grains and higher density usually improve εr consistency.

Dielectric Loss & Frequency Stability

While εr determines charge storage ability, dielectric loss (tan δ) measures energy dissipation. Materials like PTFE or h-BN have very low tan δ, making them suitable for high-frequency RF designs.

Another factor is frequency dependence. Some ceramics like zirconia have higher dielectric constants but exhibit greater loss and instability at GHz ranges, whereas AlN and Si₃N₄ remain more stable.

Dielectric Constants of Common Ceramic Materials

Ceramic Material Dielectric Constant (εr) Characteristics
Alumina (Al₂O₃) 9–10 Low loss, stable structure, cost-effective
Zirconia (ZrO₂)  18–25 High strength, high thermal expansion
ZTA20 (Zirconia Toughened Alumina) 12–15 Combines strength and dielectric properties
Silicon Nitride (Si₃N₄) 7–8 High strength, low dielectric loss
Aluminum Nitride (AlN)  8.5–9 High thermal conductivity, low dielectric loss
Silicon Carbide (SiC)  9.7–10.2 Excellent high-frequency stability
Beryllium Oxide (BeO) 6.5–7.5 High thermal conductivity, low εr
Hexagonal Boron Nitride (h-BN) ~4 Very low εr, excellent thermal stability
MGC (Machinable Glass Ceramic) 5.6 CNC machinable, ideal for microwave structures

*Data is for reference only.

Material Selection Guide: Choosing Ceramics Based on Dielectric Constant

Application Direction Recommended Materials Reason
High-frequency/Low-loss AlN, BeO, h-BN Low εr + low loss + high thermal conductivity
Power Packaging/Cooling AlN, Al₂O₃ Moderate εr + excellent heat dissipation
Radar Dome/Antenna Cover MGC, BeO Good machinability + low εr
High-frequency Capacitors ZrO₂, ZTA High εr + good mechanical strength
Microwave Structures MGC Easy to machine + stable dielectric performance

Need Help Choosing the Right Ceramic?

Understanding the dielectric properties of advanced ceramics is critical to selecting the right materials for use in electrical and electronic applications. Whether it’s RF components, power electronics, or thermal management systems, our materials deliver industry-leading performance, durability, and precision.

For custom ceramic processing and component design, Great Ceramic offers precision manufacturing solutions tailored to your material and dielectric performance needs.

Dielectric Constant: Ceramics vs Other Materials

To help you understand the advantages of ceramic dielectric constant in material selection, the following chart compares ceramic materials with common insulator materials, electronic industry materials and polymer plastics:

*Data is for reference only.

Applications based on ceramic Dielectric Constant

  • Application: RF antennas, power amplifier substrates, filters
  • Key Advantages: AlN has a moderate dielectric constant (~9) and ultra-high thermal conductivity (170–200 W/m·K), reducing signal delay and thermal buildup.
  • Case Study: A 5G base station supplier adopted AlN instead of alumina substrates, improving amplifier thermal management by 30% and significantly enhancing signal stability.

  • Application: Satellite radar systems, microwave resonators, antenna windows
  • Key Advantages: BeO offers low εr (6.5–7.5) and extremely high thermal conductivity (330 W/m·K), which minimizes microwave signal loss and improves transmission.
  • Case Study: A satellite manufacturer used BeO for microwave windows, reducing the size by 20% compared to quartz while increasing signal sensitivity.

  • Application: IC packaging, power modules, LED substrates
  • Key Advantages: Alumina offers good insulation (dielectric strength >15 kV/mm) and a stable dielectric constant (~9.8), suitable for high-density packaging.
  • Case Study: A power semiconductor company implemented 96% alumina ceramic substrates in MOSFET modules, improving insulation and maintaining excellent thermal conductivity.

  • Application: Radar structures, microwave photonic devices, signal couplers
  • Key Advantages: Stable εr (~5.6), easy to machine via CNC, suitable for complex RF/microwave designs.
  • Case Study: A defense communications firm used MGC for microwave feed structures. Compared to quartz, machining time was reduced by 30%, and dimensional consistency improved.

  • Application: High-voltage capacitors, plasma devices, impedance matchers
  • Key Advantages: High dielectric constant (18–25), ideal for applications requiring high energy density.
  • Case Study: A plasma equipment manufacturer used ZrO₂ as a dielectric layer for a plasma field capacitor, enabling more compact designs with the same energy storage.

Popular Advanced Ceramic Materials

Beryllium Oxide Ceramics with High Thermal Conductivity

Beryllium Oxide Ceramics

Aluminum Nitride Ceramics with High Thermal Conductivity

Aluminum Nitride Ceramics

Aluminum Nitride (AlN) Substrate with High Thermal Conductivity

Aluminum Nitride Substrate

Alumina ceramic substrate

Alumina Ceramic Substrate

Frequently Asked Questions (FAQ)

Due to their diverse crystal structures, densities, and electronic configurations. Some are engineered for high εr, while others prioritize insulation.

Not necessarily. For high-frequency or high-speed applications, low εr and low loss tangent are often more desirable.

Aluminum Nitride (AlN) and Beryllium Oxide (BeO) both offer excellent thermal conductivity and moderate εr.

Common methods include:

  • Resonant cavity method

  • Impedance analysis

  • Capacitance measurement via parallel plate setup

Typically between 4–10 is considered suitable for high-frequency substrates, with higher values (>20) used in capacitors.

Zirconia and Barium Titanate (not included in chart) can have very high dielectric constants, over 1000 in the latter case.

Ceramics are more stable with temperature, have better aging resistance, and higher thermal conductivity, making them ideal for harsh environments.

Alumina ceramics have a dielectric constant around 9–10, making them versatile and widely used in electronics.

Thermal conductivity of silicon carbide ceramics

Flexural strength