Thermally Conductive Ceramics

by | May 19, 2021

Thermally Conductive Ceramics

The use of ceramics in high thermal conductivity applications is a growing specialized market. Oxide ceramics are the most common base materials.  But the majority of them are limited to 26-30 W/mK which, when compared to the two most common high thermal conductivity metals, copper around 385 W/mK and aluminum around 150-185 W/mK, leaves a large gap.

The goal is to increase the thermal conductance while retaining the other key feature of ceramics, electrical insulation.

Recent developments in alumina have increased the thermal conductivity in some grades up to 39 W/mK, still far short of commonly used metals, but a significant increase from its base level.

Ceramic materials that are selected to reach toward this higher thermal conductance are a specialized group. All have their own strengths and weaknesses and not all offer the key property of electrical insulation.

Let’s look at four contenders, including Boron Nitride, Aluminum Nitride (AlN) composites, Beryllium oxide, and Aluminum Nitride. The first contender is Shapal Hi-M Soft, a composite of Aluminum Nitride and Boron Nitride, which gives a significant increase in thermal conductivity, over 92 W/mK, and improves the electrical insulation. The combination of these two materials also brings a second benefit to the material, its machinability. It does not require diamond tooling to machine. But achieving this machinable Aluminum Nitride / Boron Nitride composite requires hot pressing, which limits the available size of the material.

Boron Nitride, another hot-pressed material, is also machinable, and is available in larger pieces. Plus there are many grades available.  But only the highest purity can match the machinable AlN / Boron Nitride composite for thermal conductance and, in some cases, can outperform it. The high Purity grades are mechanically weaker and softer than the machinable Aluminum Nitride / Boron Nitride composite.

Beryllium Oxide has been the material of choice for some high-end projects for many years.  This material has a thermal conductivity of 285 W/mK, good electrical insulation, and as an oxide ceramic has none of the specialized nitrogen furnacing requirements of Aluminum Nitride. The main drawback is the health and safety requirements associated with this material, resulting in only specialized applications tending to use it, such as in military-type requirements.

Aluminum Nitride (AlN) tends to be used mainly in substrate form, as the next step up from Alumina substrates.  Most of the world’s production of AlN is in this form. The thermal conductivity of AlN depends on grade and quality.  The industry standard tends to be 170-180 W/mK, with lesser grades down to 150 W/mK, and ultra-high purity up to around 220 W/mK. AlN components in a 3D geometry are far less common. Many engineers prefer to use a machinable Aluminum Nitride composite, especially in initial design phases, but often also in production volumes as well, even though it has lower thermal conductance.

If you want the highest thermal conductance and have really deep pockets, then at over 2000 W/mK, synthetic Diamond is for you. But your thermal conductance requirement would have to be of an extreme nature.

The below table compares the thermal conductivity of 3 electrical insulators (Aluminum Nitride, Shapal, and Alumina) and 2 electrical conductors (Aluminum and Copper):

Compound ID Thermal Conductance
Aluminum Al 225 W/mK
Copper Cu 380 W/mK
Aluminum Nitride AlN 170 W/mK
Shapal (Machinable AlN) Al/BN Composite 92 W/mK
Alumina Al2O3 26 W/mK

Find more information about Shapal Hi-M Soft, Aluminum Nitride, Boron Nitride, and Alumina.

If you’re interested in these materials and want to know if it’s the right fit for your application, don’t hesitate to get in touch.

Related Pages

Shapal Hi M Soft

Shapal Hi M Soft™

Machinable AlN

Shapal Hi M Soft is a hybrid type of machinable Aluminum Nitride (AlN) ceramic that offers high mechanical strength, electrical insulation, and thermal conductivity.

Aluminum Nitride Brand Image

Aluminum Nitride

CeramAlum™

Aluminum Nitride (AlN) is an excellent material to use if high thermal conductivity and electrical insulation properties are required -- an ideal material for use in thermal management and electrical applications.

Alumina CeramAlox

Alumina (Aluminium Oxide)

CeramAlox™

Alumina, also known as Aluminium Oxide, is a hard wearing advanced technical ceramic material frequently used in a wide variety of industrial applications.

Thermal Conductivity

Thermal Conductivity

Thermal conductivity measures how easily heat is transmitted through a material. There is a growing specialist market for advanced ceramics use in applications with high thermal conductivity requirements.

Most Recent Posts

Welcoming Michele Perissinotto as Italian Market Specialist

Welcoming Michele Perissinotto as Italian Market Specialist

We are thrilled to announce that Michele Perissinotto has joined the Precision Ceramics team as a Sales Manager for the Italian market. “I am delighted to join the Precision Ceramics team! With over 28 years of experience in technical sales and leadership roles in...

Material Selection: Strength, Hardness and Toughness

Material Selection: Strength, Hardness and Toughness

How do you choose a ceramic material for mechanically demanding applications? Choosing the right ceramic for based on mechanical properties involves considering strength, toughness and hardness. These properties are distinct and actually mean different things....

Wear Resistant Ceramics: Sliding, Abrasion & Impact

Wear Resistant Ceramics: Sliding, Abrasion & Impact

How do ceramic materials perform against sliding, abrasive or impact wear?Ceramics are inherently very wear resistant due to their extreme hardness. These materials have values close to the hardest known material, diamond. They have also the capability to be machined...