Soldering technology has always played a crucial role in modern industrial production. In recent years, laser soldering has emerged as a powerful new force in the field of soldering technology. Today, we will delve into the principles, methods, and parameter settings of laser soldering, and explore its applications across various sectors.

Principles of Laser Soldering Technology

Laser soldering works by using a laser as a heat source. The laser is transmitted through optical fibers and focused on the soldering area via a laser welding head. The area absorbs the laser energy, rapidly heating and melting the solder. Once the laser stops, the area cools and the solder solidifies, forming a solder joint. Because only a localized area is heated, the rest of the component remains unaffected by the heat. The laser exposure time is usually only a few hundred milliseconds. Non-contact soldering avoids mechanical stress on the solder pads and allows for efficient use of space. During this process, laser radiation converts into thermal energy, melting the solder to complete the joint.

Methods and Parameter Settings for Laser Soldering

The methods and parameter settings for laser soldering are critical to achieving high-quality solder joints. When selecting a laser soldering system, factors such as laser power, wavelength, focal length, soldering speed/duration, temperature mode, or power mode must be considered and adjusted according to the specific soldering materials. Additionally, factors like the coating of the soldering material, surface condition, thermal conductivity, transmissivity, and absorption rate must be taken into account to ensure the stability and reliability of the solder joints.

1. Laser Power
   Fiber lasers have unique technical features: optical waveguide transmission, flexibility in robotic cooperation, suitability for large-scale production, long service life, and high electro-optical conversion efficiency. Fiber lasers typically have a conversion efficiency of 25-30% (with 976nm pumping technology exceeding 40%), which is over three times that of CO2 lasers, resulting in lower operating costs.
2. Spot Size
   The size of the laser beam spot is one of the most important variables in laser soldering as it determines the power density. The diffraction limit of the laser spot size can be calculated using diffraction theory, but the actual spot size is often larger due to lens aberrations. The simplest measurement method involves using thermal paper to burn and measure the diameter of the focal point and penetration holes. Practical measurement helps in mastering the laser power and beam effect time.
3. Material Absorption
   The absorption of the laser by the material depends on various factors such as absorption rate, reflectivity, thermal conductivity, melting temperature, and evaporation temperature. The absorption rate is particularly important. Factors affecting laser beam absorption include the material’s resistance coefficient, which correlates with the square root of the absorption rate, and the material’s surface condition, which has a significant impact on welding results.

Features of the Songsheng Photonics Laser Soldering System

1. High Precision
   Laser processing offers high precision with a spot size as small as 0.1mm, enabling micro-spacing component soldering and chip component welding.
2. Minimal Thermal Impact
   Short-duration localized heating minimizes thermal impact on the substrate and surrounding components. Different heating norms can be applied based on the type of component leads to achieve consistent soldering quality.
3. No Consumable Parts
   No soldering tips are required, eliminating the need for heater replacement and allowing for efficient, continuous operation.
4. Micron-Level Accuracy
   High precision with micron-level laser spots and power-time control exceeds traditional soldering iron capabilities, enabling soldering in spaces under 1mm.
5. Multi-Optical Path Coaxial
   CCD positioning with WYSIWYG capability reduces the need for repeated visual correction and positioning.
6. Non-Contact Processing
   Eliminates mechanical stress and static electricity caused by contact soldering.
7. Eco-Friendly Operation
   Laser technology is a clean, consumable-free processing method that is easy to maintain and operate.
8. Lead-Free Soldering
   Prevents solder joint cracks during lead-free soldering.

Laser Soldering Application Case Studies

1. Automotive Electronics
   Laser soldering is extensively used for welding electronic harnesses, sensors, and control modules in automotive electronics. It achieves high precision, improving the reliability and durability of automotive electronic products.
2. Current Sensors
   In the current sensor industry, laser soldering is used for connecting sensor electrodes to circuit boards. It enhances joint reliability and precision while minimizing thermal effects on the sensor, thus improving performance and stability.
3. Photovoltaic Renewable Energy
   Laser soldering is widely used in manufacturing solar sensors and inverter storage boards in the photovoltaic sector. It increases welding efficiency and stability, reduces material waste and energy consumption, and optimizes inverter size and production efficiency.

Conclusion

Laser soldering, as a new soldering technology, offers high efficiency, accuracy, and non-destructive advantages. It has been widely applied across various fields and is expected to play an even more significant role in the future. As laser technology continues to develop, it will provide more accurate, efficient, and energy-saving soldering solutions for the industrial manufacturing sector.