It is well known that aerospace products have very demanding space requirements. Like many industries, the electronic trend of aerospace products is also the future development direction, which requires the design of electronic products to be carried out in increasingly smaller spaces. At the same time, The density of solder joints on electronic products is also getting higher and higher. In addition, products such as military equipment, aircraft, and spacecraft need to be able to withstand the harshest environmental conditions, and product quality must meet the highest engineering standards and require the use of the highest level of safety protection components and electronic components. In many cases, traditional welding processes can no longer meet the requirements, and a new welding process that can adapt to smaller spaces is needed.
High-precision flight control in the spacecraft's communication, navigation, recording, and safety systems is a primary consideration, and more and more electronic equipment is added to the cabin environment, such as pressurization and HVAC systems, entertainment, and food service systems, These equipment need to maintain stable and reliable operation for decades, and advanced welding processes with higher requirements are exactly what lasers can achieve.
So how to effectively apply the laser soldering process?
To use laser soldering technology in automated welding, we should prepare the following three items
1. Understand the principle of laser heating
2. Understand the relevant knowledge of welding
3. Understand the integration and control of automation
Traditional soldering irons and laser soldering have different heat transfer principles. The soldering iron transfers heat through conduction, but the laser generates heat by radiating the surface of the object.
Soldering iron welding is contact welding. Through electric heat conversion, the tip of the soldering iron is heated, and then through the contact between the tip of the soldering iron and the object to be welded, the heat is transferred to the object to be welded, and the solder is melted to form an alloy layer.
Laser welding is non-contact welding. It uses a laser as the heat source, uses the excellent directionality and high power density of the laser beam to focus the laser beam on a small area through the optical system, and uses the laser beam to directly illuminate the welding part. The parts (component leads and solder) absorb light energy and convert it into heat energy. The temperature rises sharply to the welding temperature, causing the solder to melt and infiltrate. After the laser heating stops, the welding part cools rapidly and the solder solidifies to form an alloy layer. To achieve the purpose of electrical connection.
The light source of laser soldering uses semiconductor diodes, which can be precisely focused on the solder joint through an optical system. And through temperature closed-loop feedback, we can accurately control and optimize the energy required for welding. After the laser output from the laser generator is shaped and focused by the optical system, the output energy density is high and the heat transfer efficiency is high. The solder can be solder paste or tin wire, which is especially suitable for welding solder joints or small solder joints in small spaces.
What are the advantages of laser soldering technology?
1. Laser welding only locally heats the connection parts and has no thermal impact on the component body.
2. The heating speed and cooling speed are fast, the joint structure is fine, and the reliability is high.
3. Non-contact processing, there is no stress caused by traditional welding and no static electricity.
4. Different process parameters can be set according to the type of solder joints to obtain consistent welding quality.
5. The laser processing accuracy is high, the laser spot can reach the micron level, the processing time/power is controlled by the program, and the processing accuracy is much higher than traditional electric soldering iron soldering and HOT BAR soldering.
6. The small laser beam replaces the soldering iron tip and can also be operated in a small space.