High-voltage platforms impose extremely demanding requirements on power module packaging: the chips generate significant heat, requiring substrates that dissipate heat quickly; drastic temperature changes demand good thermal expansion matching; and vehicle vibrations and impacts require sufficient mechanical strength. Silicon nitride ceramics uniquely satisfy all three conditions simultaneously. In terms of thermal conductivity, commercial silicon nitride substrates typically achieve 60–90 W/(m·K), with high-performance grades reaching 90–120 W/(m·K). For thermal matching, its coefficient of thermal expansion (approx. 3.2×10⁻⁶/℃) aligns well with power chips, reducing the risk of thermal stress cracking under rapid temperature changes. Mechanically, silicon nitride has a flexural strength exceeding 800 MPa and a fracture toughness of about 7 MPa·m¹/², enabling it to withstand vehicle vibrations and extreme thermal cycling. With its comprehensive advantages, silicon nitride has become the key substrate material for high-voltage scenarios.
Industry Status
(1) Powders
The performance of silicon nitride ceramics ultimately depends on the quality of the upstream powders. Silicon nitride exists in two main crystalline forms, α and β. During sintering, the α phase transforms into elongated β-phase grains, a microstructure that enhances toughness. Therefore, powders with high α-phase content, high purity, and uniform particle size distribution are critical for producing high-performance silicon nitride ceramics. According to statistics, the global silicon nitride powder market size in 2025 is approximately RMB 580 million, with China's market at about RMB 199 million. As high-voltage platform vehicles rapidly gain traction, the demand for silicon nitride powder continues to grow. Currently, the penetration rate of 800V high-voltage platforms in China's new energy vehicle market has reached 18%, and silicon nitride powder, as a core raw material for SiC power module packaging, is seeing accelerating demand. In the powder sector, Sinoma Advanced Materials has launched a 2,000-ton high-performance silicon nitride powder project and led the formulation of the national standard for Silicon Nitride Ceramic Substrates (GB/T 45767-2025), holding a 20% global market share, ranking among the top worldwide. Jiangxi Silicon Nitride New Material produces about 5 tons per month, with orders booked through October 2026. The "combustion synthesis high-quality silicon nitride powder technology" from the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, has passed evaluation, achieving 99.5% purity and over 93% α-phase content, with a pilot production capacity of 20 tons per year. The silicon nitride powder industry is at a critical stage of transitioning from domestically usable to internationally excellent.
(2) Substrates
After sintering, the powder becomes ceramic substrates, which then require a copper bonding process for power module packaging. The current mainstream technology is Active Metal Brazing (AMB). Compared to traditional Direct Bonded Copper (DBC), AMB offers higher interfacial bonding strength and better thermal conductivity, meeting the demands of high voltage and high current.
(3) Automotive Applications
On the downstream automotive application side, BYD published an international patent (PCT/CN2025/115332) related to silicon nitride ceramics in March 2026, applying it to its own new energy vehicle industrial chain. Their models have adopted silicon nitride AMB substrate packaging solutions. Industry real world test data shows that after adopting silicon nitride AMB substrates, the thermal failure probability of main drive inverters dropped from 12% to 0.3%, and the vehicle's driving range increased by 5%–8%. From powders to substrates to automotive manufacturers, the entire industrial chain is entering a phase of accelerated growth.