Low-temperature ultrasonic brazing technology is a method that uses ultrasonic vibration energy to achieve the connection between metal and ceramic materials at a lower temperature. This technology is particularly suitable for the field of power module packaging with high thermal conductivity and high strength requirements, such as the welding of Si3N4 ceramics.
Advantages of low-temperature ultrasonic brazing:
- Low-temperature welding: It can be carried out at a temperature lower than the traditional brazing temperature to reduce thermal damage to the material.
- High thermal conductivity: It is suitable for welding materials with high thermal conductivity requirements, such as Si3N4 ceramics.
- High strength: The welded joint has high mechanical strength and stability.
- Clean and pollution-free: No flux is required, reducing environmental pollution and subsequent cleaning work.
Challenges of low-temperature ultrasonic brazing of porous Si3N4 ceramics:
- Pore structure stability: The porous structure may affect the heat transfer and ultrasonic vibration propagation during the welding process.
- Material matching: Appropriate brazing filler metal needs to be selected to ensure good wettability and connection strength.
- Process control: The optimization of low-temperature ultrasonic brazing process parameters (such as ultrasonic power, welding time, brazing filler metal temperature, etc.) is crucial.
Brazing filler metal selection:
The selection of brazing filler metal is the key to low-temperature ultrasonic brazing. For Si3N4 ceramics, active metal brazing materials are usually selected, such as titanium (Ti), zirconium (Zr), tantalum (Ta), etc. These materials can react chemically with the surface of Si3N4 ceramics to form a stable connection.
Welding process:
- Pretreatment: Ensure that the ceramic surface is clean, and special surface treatment may be required to improve the wettability of the brazing material.
- Brazing material coating: Apply an appropriate amount of brazing material on the ceramic surface.
- Ultrasonic welding: Fix the ceramic parts coated with brazing material on the ultrasonic welding machine, and complete the welding through the heat generated by ultrasonic vibration.
- Post-processing: After welding, heat treatment may be required to stabilize the performance of the joint.
Application prospects:
With the development of high power and high integration of power electronic devices, the requirements for thermal conductivity and mechanical strength of packaging materials are getting higher and higher. Low-temperature ultrasonic brazing of porous Si3N4 ceramic technology can not only meet these requirements, but also provide clean and efficient welding solutions, so it has broad application prospects in power module packaging, electronic packaging and other fields.
