In recent years, electric vehicles, electric locomotives, semiconductor lighting, aerospace, satellite communications, and other fields have entered a phase of rapid development. The electronic devices used in these fields operate under high current, high temperature, and high frequency conditions. To ensure the stability of device and circuit operation, higher demands are placed on chip carriers. Ceramic substrates offer excellent thermal performance, microwave properties, mechanical properties, and high reliability, making them widely applicable in these areas.
Based on the ceramic substrate material, the main types currently include alumina ceramic substrates, aluminum nitride ceramic substrates, silicon nitride ceramic substrates, silicon carbide ceramic substrates, beryllium oxide ceramic substrates, and boron nitride ceramic substrates.
1. Alumina
Alumina ceramics have high hardness, with a Rockwell hardness of HRA 80–90, second only to diamond. Their wear resistance is 266 times that of manganese steel and 171.5 times that of high-chromium cast iron, extending equipment service life by at least ten times under the same operating conditions. In addition, alumina ceramic substrates offer high thermal conductivity, good resistivity and thermal stability, and a low dielectric constant. As a result, they have become the preferred material for next-generation microelectronic devices and systems, and are widely used in aerospace, 5G communications, high-power semiconductors, high-power LED lighting, and other fields.
2. Aluminum Nitride
Aluminum nitride ceramics have become a very popular material in the electronics industry in recent years, owing to their high thermal conductivity (close to that of silicon carbide and beryllium oxide, and 5–10 times that of alumina), low dielectric constant and dielectric loss, good electrical insulation properties, and a coefficient of thermal expansion that matches silicon and gallium arsenide. Compared with beryllium oxide ceramics, aluminum nitride ceramics are non‑toxic and have lower production costs. Therefore, aluminum nitride ceramics are currently ideal high‑performance ceramic substrates and packaging materials, with a strong trend to gradually replace toxic beryllium oxide ceramics and low‑performance alumina ceramics. The theoretical thermal conductivity of aluminum nitride ceramics can reach 320 W/m·K. High‑purity aluminum nitride is colorless and transparent, but its properties are easily affected by chemical purity and density. Lattice defects such as impurities can cause phonon scattering and significantly reduce thermal conductivity.
3. Silicon Nitride
Silicon nitride, as an advanced ceramic material, exhibits excellent high‑temperature mechanical properties, chemical stability, thermal conductivity, and electrical insulation, making it a highly promising electronic substrate material. Silicon nitride ceramic substrates demonstrate outstanding high‑temperature mechanical properties, including high creep resistance, oxidation resistance, and wear resistance. This makes them suitable for extreme environments such as aerospace, energy, and petrochemical industries. In electronics and thermal management, silicon nitride ceramic substrates offer excellent electrical insulation and high thermal conductivity, meeting the heat dissipation and packaging requirements of high‑power, high‑frequency devices. They are widely used in power semiconductor modules, high‑frequency circuit substrates, high‑temperature electronic systems, and other important scenarios.
4. Boron Nitride
Boron nitride ceramics possess many excellent properties. Boron nitride has ultra‑high thermal conductivity, with a theoretical value for hexagonal boron nitride nanosheets as high as 1700–2000 W/(m·K). It also exhibits good high‑temperature stability and oxidation resistance. Boron nitride sublimates at 3000°C, can be used up to 900°C in an oxidizing atmosphere, up to 2000°C in vacuum, and up to 2800°C in an inert atmosphere. In semiconductor packaging, boron nitride ceramic substrates have a thermal conductivity three times that of traditional alumina substrates, effectively improving chip heat dissipation efficiency.
5. Silicon Carbide
SiC materials are mainly divided into single‑crystal and ceramic types. Single‑crystal SiC is a third‑generation wide‑bandgap semiconductor material with wide bandgap, high breakdown field strength, low on‑resistance, high saturated electron mobility, high thermal conductivity, and excellent radiation resistance. These properties make it extremely suitable for electronic devices operating in harsh environments such as high temperature or high voltage. Polycrystalline SiC (i.e., SiC ceramics) has good chemical stability, high temperature resistance, wear resistance, and corrosion resistance, and can exhibit different characteristics depending on the forming and sintering processes used.
6. Beryllium Oxide
Beryllium oxide ceramic substrates feature high thermal conductivity, high melting point, high strength, high insulation, high chemical and thermal stability, low dielectric constant, low dielectric loss, and good process adaptability. They are particularly suitable for high‑power electronic devices with extremely demanding heat dissipation requirements. However, BeO is a toxic material. The dust generated during manufacturing and use poses serious risks to human health and the environment.