Aluminum nitride is a covalently bonded III-V compound that combines high thermal conductivity with high electrical resistivity, and it is attractive where heat must be removed from a component that has to stay electrically insulated. The intrinsic lattice conductivity is high, and measurements on dense material established the baseline values against which later work is judged [1]; turning that into a commercial ceramic required control of the oxygen dissolved in the lattice, because the aluminium vacancies it creates scatter phonons and dominate the thermal resistance of a sintered body [2]. Oxide additions are what allow densification at practical temperatures, and they act by reacting with that dissolved oxygen to form an aluminate phase that removes the impurity from the grains, calcium oxide being the addition whose effect has been quantified most directly [3]. The residual grain-boundary film then sets both the thermal and the mechanical behaviour, so low-temperature routes are tuned to balance conductivity against strength [4]. Shaping by vat photopolymerisation is being developed for integrated packaging [5]. Bonding the ceramic to a metal substrate without introducing a thermal barrier remains the difficult step.
- thermal conductivity
- ceramic substrate
- sintering aid
- oxygen impurity
- phonon transport
- electronic packaging
Advanced Materials and Semiconductor Technologies·Materials Chemistry·Materials Science·Physical Sciences
References
- TANAKA, T.; SUZUKI, H. The Thermal Conductivity of Aluminum Nitride. Journal of the Ceramic Association, Japan 1970, 78, 174-175. [CrossRef]
- Lee, R. Development of High Thermal Conductivity Aluminum Nitride Ceramic. Journal of the American Ceramic Society 1991, 74, 2242-2249. [CrossRef]
- de Baranda, P.S.; Knudsen, A.K.; Ruh, E. Effect of CaO on the Thermal Conductivity of Aluminum Nitride. Journal of the American Ceramic Society 1993, 76, 1751-1760. [CrossRef]
- OKAZAKI, H.; KOBAYASHI, R.; HASHIMOTO, R.; FUKUSHI, E.; TATAMI, J. Thermal conductivity and mechanical strength of low-temperature-sintered aluminum nitride ceramics containing aluminum nitride whiskers. Journal of the Ceramic Society of Japan 2020, 128, 991-994. [CrossRef]
- Schwarzer-Fischer, E.; Scheithauer, U.; Michaelis, A. CerAMfacturing of Aluminum Nitride with High Thermal Conductivity via Lithography-Based Ceramic Vat Photopolymerization (CerAM VPP). Ceramics 2023, 6, 416-431. [CrossRef]