Thermal Conductivity Comparison of AlN vs. BeO and AlN vs. BN: Is AlN the Optimal Choice?

Engineering and technological innovations help industries move away from glass, plastic, metal, and other traditional materials that often come at a higher price. You can turn to more economical and high-performing choices, such as advanced ceramic materials that allow you to use them across different applications. Most of these materials contain excellent chemical, mechanical, and electrical properties. They are also regarded for their corrosion resistance, hardness, robustness, and wear resistance. At the same time, these options provide the much-needed thermal stability required for applications to operate successfully.

Now, the question is: which ceramic material is more reliable – Aluminum Nitride (AlN), Beryllium Oxide (BeO), or Boron Nitride (BN)? Each possesses exceptional physical strength and thermal conductivity, making them an ideal choice for automotive, electronics, and aerospace industries, which require materials with excellent heat dissipation qualities.

However, knowing which is superior to the others requires a fair understanding of their characteristics. This understanding helps analyze how they perform under high heat without compromising their integrity, which qualifies them to become an integral part of insulators, high-power equipment, heat sinks, electronic substrates, and other applications. Typically, many applications use AlN thermal conductivity and other traits. So, let’s have a comparative analysis of AlN with BeO and BN for clarity.

Thermal Conductivity of BeO vs. AlN: A Comparative Take

Aluminum Nitride and Beryllium Oxide are the two most sought-after advanced ceramics. They are chosen for their physical attributes and thermal stability across several industries and for multiple applications.

-> BeO – Physical, Chemical and Thermal Properties

This white crystalline oxide stands out for its superior strength and hardness. It is used in high-temperature environments because its melting point is around 2570°C. BeO displays outstanding corrosion resistance because it is non-reactive to many alkalis and acids under normal heat. However, it cannot resist concentrated acids. In terms of thermal properties, it is an excellent heat-conducting material, with thermal conductivity reaching up to 330 W/mK.

-> AlN - Physical, Chemical and Thermal Properties

With around 3.26 g/cm³ density, aluminum nitride offers incredible mechanical strength. It is chosen for its high heat conduction and electrical insulation capacities. Due to its specific chemical composition, the material can also tolerate oxidation and other harsh environments. Its integrity and properties can remain intact even in reducing or inert atmospheres up to 2200°C. Based on its form and material purity, AlN also shows a heat transfer ability of about 170 to 200 W/mK, comparable to other ceramic materials.

Due to higher thermal stability, BeO is used in electric insulators and substrates to dissipate heat and increase the lifespan of electronic components. Microwaves and laser tubes also benefit from it. This ceramic material has broader applications because its crystal structure helps transfer heat. Unfortunately, this material must be carefully handled with adequate safety measures to avoid its toxic effects during production and recycling.

AlN can be used in non-toxic environments for its suitable thermal conductivity. Think of semiconductor devices and LEDs, for instance. The material acts like a heat sink to dispel heat from active areas and increase the performance of the devices. Because of its non-toxic nature, it is also helpful in power electronic applications.

To sum up, BeO is more reliable in high-temperature conditions where some toxicity risks can be taken. On the other hand, AlN is better suited for industrial conditions and consumer electronics, where safety and health are prioritized. They benefit more from their thermal management and non-toxicity.

Thermal Conductivity Competitive Analysis of AlN and BN

Ceramic materials’ growing use case in specialized applications that need high thermal conductivity or resistance makes industrialists and manufacturing companies search for more and more alternatives. You already know BeO faces restrictions due to its toxic nature. However, there is another material like BN, which also promises a better experience. However, how it fares against AlN needs to be seen.

BN is a hot-pressed material available in large solid pieces or powder form. It has many grades that determine the product’s purity levels. Only the highest purity material can offer excellent thermal conductance and outperform others. That means the thermal conductivity of BN is subject to high purity standards. Still, one must remember they may lack mechanical strength and be softer.

AlN is primarily accessed in substrate form worldwide. AIN’s thermal conductivity can vary depending on its quality and grade. High purity levels are around 220 W/mK, industry standard is 170-180 W/mK, and lesser quality stands at 150 W/mK. Nevertheless, AlN’s mechanical strength and thermal stability suit diverse applications, such as semiconductor substrates, heat sinks, and other electronics. BN is helpful in environments where lubrication and thermal resistance are needed. In hexagonal form, BN is widely applied in aerospace and nuclear fields. They are used in coatings and lubricants.

The use case of AlN in PCBs and Semiconductors

In addition to thermal conductivity, the ceramic material’s ability is also examined in terms of its Coefficient of Thermal Expansion (CTE). CTE helps track fractional changes in the material’s length when exposed to different temperatures at the same pressure. Aluminum nitride CTE is relatively low, making it much better than other advanced ceramics and highly reliable for various key applications such as Printed Circuit Boards (PCBs) and semiconductors.

Benefits of AlN in PCBs

PCBs are used across various industries, such as telecommunications, energy, aerospace and defense, automobile, etc. However, let’s take an example of medical devices, which are part of a healthcare industry that is growing rapidly due to increased demands. Medical equipment needs to have good heat management capacity and be safe. AlN’s integration in PCBs helps achieve these goals. Because of AlN’s higher heat dissipation, insulation, performance, and low maintenance requirements, medical devices become durable and reliable. The material is applied in high-stakes devices like diagnostic equipment and medical imaging. Its thermal conductivity range is 170-200 W/mK. Due to this, it can manage heat well, even in high-powered devices like medical lasers and CT scanners.

Likewise, AlN’s optimum dielectric strength range is 15-20 kV/mm, making it safe for high-voltage equipment that requires protection from electrical interference without compromising performance.

Medical devices are making rapid strides in technology. Advanced equipment benefits from AlN’s thermal conductivity, stability, and low-maintenance traits. However, the material is constantly being upgraded or refined to develop and maintain higher moisture and heat resistance standards for wearables and less invasive medical tools.

Benefits of AlN in the Semiconductor Industry

AlN CTE, insulation voltage, strength, and other qualities make it an apt choice for the semiconductor field. The aluminum nitride compound has a hexagonal structure with covalent bonds and a = 3.114 and c = 4.986 lattice parameters. Materials with high purity levels look bluish-white, and AlN normally behaves in its off-white color. Considering its electrical properties, you will find that pure AlN’s electronegativity at room temperature is more than 1014Ω-cm, showing its insulating strength. Its electromechanical coupling CTE is 0.8%. This material’s corrosion resistance is another attractive proposition that shows it can resist many types of metals and molten salts, such as copper, lead, aluminum, nickel, silver, gallium arsenide, etc.

It is counted among the 3rd generation semiconductor materials for providing excellent electron saturation point, radiation resistance, electric field, and band gap. Studies suggest that AlN can tolerate 7.3 megavolts of electric field per cm, much better than silicon like gallium nitride and silicon carbide. Plus, AlN systems also allow a smooth flow of current. However, one challenge this material faces is doping—introducing impurity elements to improve a semiconductor’s charge carrier concentration. Still, it’s an emerging strategy, and researchers are continuously working on ways to make AlN a perfect fit for semiconductors.

Conclusion

Advanced ceramic materials, such as AlN, Beo, and BN, are both cost-efficient and high-performing compared to metal, glass, and plastic. However, these ceramic substrates are unique and are used in different environments based on their composition and risk factors. For instance, the non-toxic AlN is widely used in many applications for its thermal stability and conductivity.

FAQs

What exactly is AlN?

Electrical devices and other sectors always look for better materials with high thermal management performance because of their insulation and heat transfer capabilities. AlN can quickly meet these expectations. It is also considered a safer alternative for the semiconductor industry than BeO. You can also consider it a technical ceramic material.

What is the purpose of AlN ceramics?

Extraordinary insulation, thermal conductivity, low dielectric loss, and ability to withstand plasma erosion are the strengths that allow this material to be combined in semiconductor equipment, OLEDs, and other devices for longevity and remarkable performance.

What precautions should one take when working with AlN ceramics?

They cannot be immersed in water, alkalis, inorganic acids, or other such materials because of the chances of chemical reactions. However, AlN remains unaffected by cryolite, chloride, and other molten salts.

What can be done to protect AlN PCBs from moisture problems in medical devices?

AlN’s performance can be secured and safeguarded through encapsulation and protective coatings.

 Where do you use AlN?

As hinted above, it can be used in lasers, heat spreaders, heat sinks, semiconductor devices, silicon wafer processing, microelectronic devices, electronic packages, sensors and detectors, and more.