In recent years, ceramic substrates that have been mass-produced and widely used mainly include: Al2O3, BeO, SiC, Si3N4, AlN, etc.
Due to its simple preparation process, good insulation and high temperature Ceramic Flange resistance, Al2O3 currently occupies an important position in the heat dissipation substrate industry. However, the thermal conductivity of Al2O3 is low, which cannot meet the development requirements of high-power and high-voltage devices. It is only suitable for working environments with low heat dissipation requirements, and the low bending strength also limits the application range of Al2O3 ceramics as a heat dissipation substrate.
Although BeO ceramic substrate has high thermal conductivity and low dielectric constant to meet the requirements of efficient heat dissipation, but due to its toxicity, it has an impact on the health of workers and is not conducive to large-scale applications.
AlN ceramics have high thermal conductivity and are considered as candidates for heat-dissipating substrates. However, AlN ceramics have poor thermal shock resistance, easy deliquescence, and low strength and toughness, which are not conducive to working in complex environments, and it is difficult to ensure the reliability of their applications.
Although SiC ceramic has high thermal conductivity, it is not suitable for application in high frequency and high voltage working environment due to its high dielectric loss and low breakdown voltage.
Silicon nitride is recognized at home and abroad as a ceramic substrate Alumina Ceramic Tube material with the best comprehensive properties such as high thermal conductivity and high reliability. Although the thermal conductivity of Si3N4 ceramic substrate is slightly lower than that of AlN, its flexural strength and fracture toughness can reach more than 2 times that of AlN; at the same time, the thermal conductivity of Si3N4 ceramics is much higher than that of Al2O3 ceramics; in addition, the thermal expansion of Si3N4 ceramic substrates The coefficient is close to that of the third-generation semiconductor substrate SiC crystal, making it more Ceramic Part stable to match with the SiC crystal material. This makes Si3N4 the first choice for high thermal conductivity substrate materials for 3rd generation SiC semiconductor power devices.
In this article, the editor will take stock of the applications of Si3N4 ceramic substrates in new energy vehicles.
Due to its simple preparation process, good insulation and high temperature resistance, Al2O3 currently occupies an important position in the heat dissipation substrate industry. However, the thermal conductivity of Al2O3 is low, which cannot meet the development requirements of high-power and high-voltage devices. It is only suitable for working environments with low heat dissipation requirements, and the low bending strength also limits the application range of Al2O3 ceramics as a heat dissipation substrate.
Although BeO ceramic substrate has high thermal conductivity Mechanical Ceramic Parts and low dielectric constant to meet the requirements of efficient heat dissipation, but due to its toxicity, it has an impact on the health of workers and is not conducive to large-scale applications.
AlN ceramics have high thermal conductivity and are considered as candidates for heat-dissipating substrates. However, AlN ceramics have poor thermal shock resistance, easy deliquescence, and low strength and toughness, which are not conducive to working in complex environments, and it is difficult to ensure the reliability of their applications.
Although SiC ceramic has high thermal conductivity, it is not suitable for application in high frequency and high voltage working environment due to its high dielectric loss and low breakdown voltage.
Silicon nitride is recognized at home and abroad as a ceramic substrate material with the best comprehensive properties such as high thermal conductivity and high reliability. Although the thermal conductivity of Si3N4 ceramic substrate is slightly lower than that of AlN, its flexural strength and fracture toughness can reach more than 2 times that of AlN; at the same time, the thermal conductivity of Si3N4 ceramics is much higher than that of Al2O3 ceramics; in addition, the thermal expansion of Si3N4 ceramic substrates The coefficient is close to that of the third-generation semiconductor substrate SiC crystal, making it more stable to match with the SiC crystal material. This makes Si3N4 the first choice for high thermal conductivity substrate materials for 3rd generation SiC semiconductor power devices.
The applications of Si3N4 ceramic substrates on Machinable Ceramic new energy vehicles.
Si IGBT
IGBT is the core device of the motor Zirconia Ceramic Pin control system of new energy vehicles, accounting for about half of the cost of the motor drive system, while the motor drive system accounts for 15-20% of the cost of the whole vehicle, which means that the IGBT accounts for 7-10% of the cost of the whole vehicle. In addition to the battery, the second most expensive component, the quality of the IGBT also determines a large part of the energy efficiency of the vehicle.
Since the IGBT has been put into the market for so many years, its own potential has been tapped almost, and everyone has shifted their energy to the packaging of the IGBT, that is, heat dissipation. The heat dissipation efficiency requirements of automotive IGBTs are much higher than those of industrial grades. The temperature in the inverter is extremely high, and strong vibration conditions must be considered at the same time. The IGBTs of automotive grades are far above the industrial grades. The power conductive terminals of IGBT modules for electric vehicles need to carry large currents of hundreds of amperes, which have high requirements on electrical conductivity and thermal conductivity. They also have to withstand certain vibration and impact forces in the vehicle environment, and have high mechanical strength requirements.
For automotive IGBTs, Alumina Ceramic Tube silicon nitride is perfect. Silicon nitride ceramic circuit boards can adapt to high temperature and high pressure working environment. It can dissipate the high heat in the power system in time, adapt to the harsh environment inside the car, and protect the chip from working normally while the major Ceramic Part power loads are running normally. Extend the life of electronic equipment. Save more space and provide more possibilities for new energy vehicles.
SiC MOSFETs
In the core motor drive of new energy vehicles, the use of SiC MOSFET devices brings a 5% to 10% improvement in battery life compared to traditional Si IGBTs, and will Ceramic Flange gradually replace Si IGBTs in the future. However, SiC MOSFET has a small chip area and high requirements for heat dissipation. The silicon nitride ceramic substrate has excellent heat dissipation capability and high reliability, which has almost become a must for SiC MOSFET main drive applications in the field of new energy vehicles.
The Tesla model 3, which has been mass-produced, has used silicon nitride ceramic substrates in large quantities to deal with heat dissipation of SiC MOSFET devices.
The new generation of SiC electronic control launched by BYD e3.0 platform adopts the self-developed new SiC MOSFET motor control module, high-performance silicon nitride ceramics and integrated NTC sensor, which increases the power density of the entire electronic control unit by nearly 30%, and the current is the largest It supports 840A, the maximum voltage is 1200V, and the maximum efficiency of electronic control is 99.7%.