Determination of dielectric properties of Al₂O₃ and AlN ceramics at up to 1000°C and MHz frequencies

Infinita Lab network laboratories are well equipped to measure the dielectric properties of ceramics at temperatures (up to 1000 °C) and MHz frequencies. Al₂O₃ and AlN ceramics have many high-temperature applications at MHz frequencies. For example, polycrystalline Al₂O₃ and AlN are routinely used in packaging and substrate applications. High purity and stable quality ceramic substrates are crucial in applications like LED packages, the substrate for chip resistors, HIC substrates for heat dissipation, power modules, FAX substrates for thermal printer heads, etc. Conventional testing to evaluate these materials’ electrical properties has a limited temperature range from room temperature to 350 °C. However, testing ceramics at high temperatures and MHz frequencies is crucial to understand their properties and performance relationship but is not currently offered by any lab. 

Below is an example of the dielectric constant (Figure 1) and the dissipation factor (Figure 2) at varying temperatures and frequencies.

Fig. 2. Dissipation factor of 96% Al₂O₃ at various temperatures and frequencies. Reference [1]

With increased scope for Al₂O₃ and AlN materials in high-temperature applications, measurement of dielectric properties at high temperatures and MHz frequencies is becoming increasingly important. However, measuring dielectric constant at high temperatures (700 °C) and MHz frequencies is complex and not offered by most laboratories. Infinita Lab provides unconventional electrical testing of these ceramics at temperatures from room temperature to as high as 650 °C using the AC impedance method at the following frequencies: 350 kHz, 15 MHz, 30 MHz. The tangent loss is in the order of 10-4 and negligible to be measured with acceptable accuracy. Infinita Lab partners provide these tests with relative success.Measuring the dielectric properties of polycrystalline Al₂O₃ and AlN substrates at high temperatures is critical to understanding their temperature dependency.

[1] Chen, L., & Hunter, G. (2004). Temperature-Dependent Dielectric Properties of Polycrystalline 96%Al2O3. MRS Proceedings, 833, G7.6. doi:10.1557/PROC-833-G7.6