What are the main aspects of the insulation properties of alumina ceramics

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As a high-performance engineering material, alumina ceramics have excellent electrical insulation performance, which is one of its most core and well-known characteristics, and also the basis for its wide application in electronics, power, aerospace and other fields.

Core performance of insulation of alumina ceramics
The insulation performance of alumina ceramics is not a single indicator, but a reflection of comprehensive performance, mainly covering the following aspects:

1. Extremely high volume resistivity and surface resistivity
   Performance: Alumina ceramics have extremely high volume resistivity at room temperature (usually greater than 10 ¹⁴Ω· cm) and surface resistivity of up to 10 ¹² -10 ¹³ Ω. This means that current is extremely difficult to pass through its interior and surface, effectively blocking leakage current paths.
   Comparison: Its resistivity is much higher than that of ordinary organic insulation materials such as plastics and rubber, and it can still maintain a high value even in high temperature environments.
2. Excellent dielectric strength (breakdown strength)
   Performance: Dielectric strength refers to the maximum electric field strength that a material can withstand before breakdown (failure), measured in kV/mm. The dielectric strength of high-purity alumina ceramics (such as 96% and 99% ceramics) can usually reach 10-25 kV/mm or even higher.
   Meaning: This means that under high voltage conditions, alumina ceramics can withstand extremely strong voltages without being broken down, ensuring the safe and stable operation of high-voltage electrical devices.
3. Lower dielectric constant and dielectric loss
   Dielectric constant: The dielectric constant of alumina ceramics is usually between 8-10 (at 1MHz), and the value is relatively stable. A lower dielectric constant helps reduce delay and cross interference during signal transmission, especially suitable for high-frequency circuits.
   Dielectric loss: Its dielectric loss tangent (tan δ) is very low (usually less than 0.0004 @ 1MHz). Low loss means that in an alternating electric field, there is minimal loss in converting electrical energy into thermal energy, resulting in high energy transfer efficiency and low heat generation.
4. Excellent high-temperature insulation stability
   Performance: Unlike organic insulation materials such as plastics and epoxy resins, which soften, carbonize, and lose their insulation properties at high temperatures, the insulation performance of alumina ceramics decreases very little with increasing temperature. It can maintain stable insulation performance for a long time in temperature environments of 500 ℃ or even higher.
   Mechanism: Its stable crystal structure composed of ionic and covalent bonds endows it with extremely high melting point and thermal stability.

How to solve practical problems with the insulation properties of alumina ceramics
It is precisely based on the excellent insulation properties mentioned above that alumina ceramics have become a key material for solving many industry pain points.

1. Solve the insulation problem in high-temperature environments
   Problem: In metallurgical, aerospace engine, high-power LED, household appliance heating wire and other scenarios, the working temperature is extremely high, and ordinary insulation materials are unable to handle it.
   Solution: Use alumina ceramic as insulation substrate, coil skeleton, thermocouple sleeve, lamp holder, etc. For example, the heating plate in a rice cooker has its internal heating wires insulated and fixed by embedding them in alumina ceramics, ensuring absolute safety in high-temperature boiling environments.
2. Ensure the safety and miniaturization of high-voltage electrical appliances
   Problem: High voltage transmission and transformation equipment, vacuum circuit breakers, laser generators, X-ray tubes, etc. need to withstand voltages of tens or even hundreds of thousands of volts, requiring insulation components to have extremely high breakdown strength.
   Solution: Aluminum oxide ceramics are used to make vacuum arc extinguishing chambers, high-voltage insulators, high-voltage sockets, electronic tube casings, etc. Its high dielectric strength ensures that the equipment is not broken down under high voltage, while its high mechanical strength allows the equipment to be designed more compactly, achieving miniaturization.
3. Improve the signal integrity of high-frequency electronic devices
   Problem: In 5G communication base stations, RF modules, semiconductor integrated circuits, and microwave devices, high-frequency signals are highly sensitive to the dielectric constant and losses of substrate materials. Poor materials can lead to signal distortion, attenuation, and heating.
   Solution: Use alumina ceramic substrate (such as thick film circuit, thin film circuit substrate) or packaging shell. Its stable low dielectric constant and extremely low dielectric loss ensure low loss, high fidelity, and high efficiency in high-frequency signal transmission, which is incomparable to ordinary PCB boards.
4. Achieve reliable insulation in arc resistant and corrosion-resistant environments
   Problem: In harsh environments with strong arcs, corrosive gases or liquids, the surface of materials may be carbonized or corroded, leading to insulation failure.
   Solution: Alumina ceramics have high hardness, corrosion resistance, non aging, and are not easily carbonized on the surface. Used for manufacturing arc nozzles, chemical sensor insulation housings, semiconductor etching equipment components, etc., it can provide lifelong reliable insulation protection under these harsh conditions.

The insulation properties of alumina ceramics are a comprehensive reflection of high performance, high reliability, and high stability. It is not simply “non-conductive”, but can still perform its insulation duties stably, efficiently, and safely under extreme harsh conditions such as high temperature, high pressure, high frequency, and corrosion.
Choosing alumina ceramics as insulation components means choosing:
Higher safety: eliminate the risk of leakage and breakdown.
Longer service life: resistant to aging, performance does not deteriorate over time.
Better equipment performance: Especially in the high-frequency and high-voltage fields, it can significantly improve the overall efficiency of the equipment.
Wider application scope: Breaking through temperature and environmental limitations, opening up new possibilities for product design.
Therefore, when your product design faces severe insulation challenges, alumina ceramics are undoubtedly a time proven, powerful, and reliable solution.

Brudeze Ceramics supplies and sells a wide range of high-quality quartz glass, including alumina ceramics, zirconia ceramics, silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics, boron carbide ceramics, bioceramics, machinable ceramics, etc. We can meet the customization requirements of various ceramic products.