Enhanced mechanical and thermal properties of AlN ceramics via a chemical precipitation process

Abstract

Aluminum nitride (AlN) ceramics are promising materials for the thermal management of high power electronics, photovoltaic moduli, and LEDs, because of their high thermal conductivity (the intrinsic thermal conductivity ≈319 W m −1 K −1 ), high electrical resistivity, low dielectric constant, no toxicity, and a coefficient of thermal expansion close to that of silicon. [1][2][3] Up until now, substantial research efforts have been made to enhance the thermal conductivity of AlN ceramic. [4][5][6] The high power density in power electronics applications can cause crack propagation and fatigue failure in ceramic substrates owing to high thermal stresses arising at the joints with circuits. 7,8 Therefore, besides the high thermal conductivity, the superior mechanical strength is also significant for AlN ceramics to be widely useful. Some studies recently have been focused on improving the bending strength of AlN ceramics. Kusunose et al 9 achieved the high bending strength of 433 ± 19 MPa for AlN ceramic with Y 2 O 3 -CeO 2 additives, but its thermal conductivity is just 136 W m −1 K −1 . Beyond

A simple method for preparing ThO2 ceramics with high density

“…The experimental results of thermal conductivity, thermal diffusivity, and specific heat capacity are presented in Figure 7. The thermal diffusivity of ThO 2 ceramic was determined using an LFA, and the thermal conductivity was calculated by the following equation: $$$$\begin{equation}\lambda = \rho \alpha {C_p}\end{equation}$$$$where λ is the thermal conductivity, α is the thermal diffusivity, C p is the specific heat capacity, and ρ is the ceramic density 36 . The specific heat capacity of ThO 2 ceramic was determined by using the sapphire method from the TG‐DSC measurement, and its density was determined by the Archimedes method.…”

“…where λ is the thermal conductivity, α is the thermal diffusivity, C p is the specific heat capacity, and ρ is the ceramic density. 36 The specific heat capacity of ThO 2 ceramic was determined by using the sapphire method from the TG-DSC measurement, and its density was determined by the Archimedes method. Such value of thermal diffusivity corresponds to the relative density of ThO 2 between 95.0% and 99.0%, which was proved by Malakkal.…”

Effect of laser parameters and atmosphere in the structuring of aluminum nitride

“…Aluminum nitride (AlN) ceramic has good comprehensive properties such as reliable insulation, low dielectric loss, good mechanical properties, and thermal conductivity. Therefore, this material is regarded as a new generation of high‐performance ceramic material and is widely used as substrate materials for high‐power electronic devices 1–3 . But AlN ceramic needs metallization to form a conductive metal layer.…”

“…Therefore, this material is regarded as a new generation of high-performance ceramic material and is widely used as substrate materials for high-power electronic devices. [1][2][3] Hao Dong is the co-first author.…”

Amorphous AlN films grown by ALD from trimethylaluminum and monomethylhydrazine

“…Aluminium nitride thin films have gained attention due to their excellent electrical and mechanical properties, namely, their wide bandgap, good piezoelectric response, high resistance to bending, and remarkable thermal and chemical stability, and their optical properties; consequently they found application in sensors, light-emitting diodes, or as insulating layers. [1][2][3][4][5][6][7][8] Emerging devices of great interest are high electron mobility transistors, where AlN layers are used as buffer layers for GaN films to compensate for the misfit of the lattices and the thermal expansion between the substrate and GaN. 9,10 AlN thin films have been deposited using various chemical and physical methods, including metal organic vapor phase epitaxy, ion-beam deposition and magnetron sputtering.…”