Abstract
It is possible to improve the machinability of aluminum nitride-hexagonal boron nitride (AlN-h-BN) ceramics while maintaining high strength and high thermal conductivity. The composite ceramics with 0–30 wt% BN as secondary phase were prepared by hot pressed sintering, using yttrium oxide (Y2O3) as sintering aid. The phase composition, density, microstructure, mechanical properties, thermal conductivity, and dielectric properties were investigated. The sintering additives were favorable to purify the grain boundaries and improve densification, reacting with oxide impurities on the surface of raw material powder particles. The optimum BN content improved the flexural strength and fracture toughness of composite ceramics with 475 MPa and 4.86 MPa·m1/2, respectively. With increasing the amount of BN, the thermal conductivity and hardness of composites gradually decreased, but the minimum value of thermal conductivity was still 85.6 W·m−1·K−1. The relative dielectric constant and dielectric loss tangent of the samples ranged from 6.8 to 8.3 and from 2.4 × 10−3 to 6.4 × 10−3, respectively, in 22–26 GHz.
Highlights
In recent years, the development of large-scale integrated circuits, semiconductor module circuits, high-power devices, and 5G technology has placed higher requirement on heat dissipation and packaging ceramic materials
The new phases of YAlO3 (YAP) and Y4Al2O9 (YAM) were found out in the patterns. This is because Y2O3 reacted with oxidizing impurities in the raw powders to form the new phases at high temperature in which Al2O3 originated from the spontaneously oxidation of raw a>]. Beryllium oxideAluminum nitride (AlN) powder
Similar phenomena have been reported in the AlN ceramics sintering process [24,25,26]
Summary
The development of large-scale integrated circuits, semiconductor module circuits, high-power devices, and 5G technology has placed higher requirement on heat dissipation and packaging ceramic materials. Aluminum nitride (AlN) ceramic has some excellent properties, such as good insulation, high thermal conductivity, low density, high strength, high temperature resistance, melt metal corrosion resistance, and low dielectric constant [5,6,7], considering to be an ideal material for new generation of highly integrated semiconductor substrates and electronic device www.springer.com/journal/40145. He et al [21] prepared AlN–BN composites using Sm2O3–CaF2 as sintering additives by spark plasma sintering They researched the additives and h-BN content on the properties of samples, showing that the highest thermal conductivity value was 85 W·m−1·K−1 when introducing 8 wt% sintering aids. The purpose of this work is to improve the machinability of composites and at the same time make the AlN–BN ceramics have the relatively high thermal conductivity and good mechanical properties
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