Ceramic sheet

aluminasilicon nitridealuminum nitride

In the electric drive system (motor driver/Inverter) of new energy vehicles, the IGBT power module or power semiconductor module is the core component. They are responsible for converting the direct current (DC) from the battery into alternating current (AC) to drive the motor, while also withstanding high currents, high voltages, and frequent thermal cycles. Silicon nitride (Si3N4) ceramic substrates, with their high thermal stability, high mechanical strength, and excellent electrical insulation properties, have become an indispensable basic material for these power modules.It is usually used as the internal support and heat dissipation substrate within the module, directly supporting IGBT or diode chips, and combining with the copper leads or metallization layers in the module packaging to form an “insulated and highly conductive” core structure, thereby ensuring the stable operation of the electric drive system under high power density and harsh environments.Function and Role:Heat Dissipation: When the power module is operating, it generates a large amount of heat. The silicon nitride substrate conducts the heat quickly to the heat sink or cooling system through its high thermal conductivity, preventing the chip from overheating and enhancing the stability of the module. The thermal conductivity of silicon nitride (80-90 W/(m·K)) is not the highest, but its unique combination of high thermal conductivity and high mechanical strength makes it ideal for intense temperature variations and strong vibration environments.Electric Insulation: The IGBT chips inside the power module need to be electrically insulated from the external metal structure, while at the same time ensuring that heat can be conducted. The silicon nitride substrate has high electrical insulation properties and moderate thermal conductivity, meeting the “thermal-conductive insulation” requirement of this design. This ensures that the working voltage of up to several hundred or even thousands of volts is firmly contained within the module, isolated from the grounded casing and the cooling system, thus guaranteeing the basic safety of the system.Structural Support: The internal chips, pads, and metal layers of the power module all need to be stably supported. The silicon nitride substrate provides high mechanical strength and resistance to thermal stress, preventing the module from warping or cracking under high-temperature thermal cycling. Its flexural strength and fracture toughness are more than twice that of aluminum nitride, ensuring long-term stability of the physical structure.Enhanced Reliability: The electric vehicle undergoes frequent starting and braking operations, and the power module needs to withstand a large number of thermal cycles. Silicon nitride substrates have excellent thermal shock stability, which can significantly enhance the module lifespan and the overall vehicle reliability. Power modules using silicon nitride substrates can achieve a temperature cycling life that is approximately one order of magnitude longer than that of traditional alumina or aluminum nitride substrates.Application Forms:Metallized Si₃N₄ Substrate: The surface of the silicon nitride substrate needs to undergo metallization treatment (such as the traditional Mo/Mn method, or the current mainstream active metal brazing/AMB technology) to form metal circuits that can be used for welding and electrical connection. AMB technology, with its higher copper layer bonding strength and excellent thermal conductivity, has become the preferred solution to meet the stringent requirements of automotive-grade power modules for high power density, long lifespan, and high reliability.Direct Integration in EV Power Modules: In the electric drive system of new energy vehicles, the silicon nitride substrate, which serves as the core carrier for insulation, heat dissipation, and structural support in a “three-in-one” manner, is directly encapsulated within the power module of the main inverter. It fixes the power chip upwards and downwards, and is closely coupled with the module’s liquid cooling heat dissipation system through thermal conductive materials, achieving efficient heat conduction of the chip. This design ensures stable output power and reliable long-term performance even during intense thermal cycles.Caractéristiques / Spécifications techniques :Material: Silicon Nitride (Si₃N₄) CeramicThermal Conductivity: 80-90 W/(m·K)High mechanical strength and fracture toughness (more than twice that of aluminum nitride)Excellent electrical insulation propertiesHigh resistance to thermal shock and cyclingApplication: Internal support and heat dissipation substrate for IGBT/power semiconductor modules in electric drive systems of new energy vehiclesMetallization options: Mo/Mn method, Active Metal Brazing (AMB)Direct integration with EV power modules and liquid cooling systems