In today’s era of rapid technological development, electronic chips are moving towards higher comprehensive performance and smaller overall size. However, this development trend also brings a severe challenge – the heat flux density of the chip during operation has increased significantly. For electronic devices, the effective life will decrease by 30% – 50% for every 10°C increase in temperature. In this context, the selection of suitable packaging materials and processes and the improvement of device heat dissipation capacity have become the key bottlenecks in the development of power devices.
The packaging substrate plays a vital role in electronic devices. It mainly relies on the high thermal conductivity of the material itself to smoothly export heat from the chip (heat source) and then realize heat exchange with the external environment. At present, commonly used packaging substrates can be roughly divided into polymer substrates, metal substrates and ceramic substrates. For power device packaging, in addition to meeting the basic wiring function, the packaging substrate also needs to have high thermal conductivity, heat resistance, insulation, strength and thermal matching performance. Because of this, the use of polymer substrates and metal substrates is greatly restricted. Ceramic materials have become an ideal choice for power device packaging substrates due to their excellent properties such as high thermal conductivity, good heat resistance, high insulation, high strength, and thermal matching with chip materials. They have been widely used in many fields such as semiconductor lighting, laser and optical communications, aerospace, automotive electronics, and deep-sea drilling.
At present, commonly used electronic packaging ceramic substrate materials include aluminum oxide, silicon carbide, aluminum nitride, silicon nitride, beryllium oxide, etc. Among them, aluminum nitride and silicon nitride ceramic substrates have attracted much attention.
The performance of aluminum nitride ceramics is excellent. Its theoretical thermal conductivity is as high as 320W/(m·K), and the thermal conductivity of commercial products is generally between 170-250W/m·K, which makes it a high-quality material for high-power, high-lead and large-size chip packaging substrates. In addition, aluminum nitride ceramics also have high mechanical strength and chemical stability, and can maintain normal working conditions even in harsh environments. It is precisely because of these outstanding advantages that aluminum nitride ceramics stand out among many ceramic substrate materials and become a typical representative of the new generation of advanced ceramic packaging materials.
Silicon nitride ceramics also have their unique advantages. The thermal conductivity of Si3N4 materials is relatively low, which is mainly caused by factors such as defects and impurities in the lattice. However, researchers have conducted a lot of research to improve the thermal conductivity of Si3N4 materials. Through continuous process optimization, the thermal conductivity of silicon nitride ceramics is gradually improving. In addition, the biggest highlight of Si3N4 ceramics is its extremely low thermal expansion coefficient. Among all kinds of ceramic materials, except SiO2 (quartz), its thermal expansion coefficient is almost the lowest, only 3.2×10⁻⁶/℃, which is about 1/3 of Al2O3.
Overall, the biggest advantage of aluminum nitride ceramic substrates is their high thermal conductivity. At the same time, it also has a thermal expansion coefficient that matches semiconductor materials such as Si, SiC and GaAs, and performs well in solving the heat dissipation problem of high-power devices. Silicon nitride ceramics are known for their comprehensiveness. Among the existing ceramic materials that can be used as substrate materials, Si3N4 ceramics have a bending strength of more than 800MPa and excellent wear resistance. They are known as the ceramic material with the best comprehensive mechanical properties. In a heat dissipation environment with high strength requirements, they perform better than other materials.
In summary, both aluminum nitride and silicon nitride will become the most noteworthy substrate materials in the future. They have broad application prospects and important research value in the field of chip heat dissipation. Who can occupy a stronger position in the “war” of chip heat dissipation remains to be proved by further research and practice.