Silicon Nitride Ceramic Substrate

Silicon Nitride Ceramic Substrate is a high-performance ceramic substrate made of silicon nitride (Si₃N₄) as the core material. Its main components are silicon (Si) and nitrogen (N) elements, which are chemically bonded to form Si₃N₄. During the manufacturing process, a small amount of sintering aids, such as aluminum oxide (Al₂O₃) or yttrium oxide (Y₂O₃), are usually added to help the material form a dense and uniform microstructure at high temperatures.

The internal crystal structure of silicon nitride ceramic substrates is primarily β-phase, with interlocking grains forming a stable honeycomb network. This unique arrangement imparts high mechanical strength and excellent thermal shock resistance to the material. The dense structure, achieved through high-temperature sintering, results in excellent thermal conductivity, strength, heat resistance, and corrosion resistance. It is widely used in electronics, power equipment, and aerospace, typically serving as a heat dissipation platform or insulating support component for electronic components.

Silicon nitride is trusted as a ceramic substrate because it meets the growing demands for thermal control and structural reliability in compact, high-power electronic devices. As device density increases, traditional substrates struggle to cope with thermal stress and mechanical loads.

Silicon nitride substrates maintain mechanical stability even under rapid thermal cycling. This makes them ideal for IGBTs, power modules, and automotive inverter circuits, where power dissipation is high and failure is unacceptable.

It is also favored in RF applications, where substrates must support fine-line circuitry and maintain a stable dielectric constant—a balance of electrical and thermal properties difficult to find in traditional materials.

Silicon Nitride Substrate Properties

1. Thermal Conductivity

With a thermal conductivity of approximately 80–90 W/(m·K), silicon nitride substrates outperform alumina ceramics in heat dissipation. For example, in electric vehicle power modules, silicon nitride substrates can reduce chip temperatures by over 30%, thereby improving efficiency and reliability.

2. Mechanical Strength

Its three-point bending strength can exceed 800 MPa, approximately three times that of alumina ceramics. Tests have shown that a 0.32 mm thick substrate can withstand a pressure of 400 N without cracking.

3. Thermal Stability

Its stable operation range is -50°C to 800°C, and its coefficient of thermal expansion is as low as 3.2 × 10⁻⁶/°C, making it well-matched with semiconductor materials. For example, in a high-speed train traction inverter, switching to a silicon nitride substrate reduced the failure rate due to rapid temperature changes by 67%.

4. Insulation Performance

At room temperature, its volume resistivity is greater than 10¹⁴ Ω·cm, and its dielectric breakdown strength is 20 kV/mm, fully meeting the insulation requirements of high-voltage IGBT modules.

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