What is laser tin soldering?

Laser soldering is a precision soldering technology that uses a laser as a heat source, which is the process of heating the solder material through a laser to melt it and then connect electronic components or materials. This technology has a wide range of applications in fields such as microelectronics manufacturing, automotive electronics, aerospace, medical devices, etc., which require high precision and high reliability. Laser soldering, an advanced welding technology, has been widely used in electronic manufacturing, aerospace, automobile manufacturing and other fields in recent years.

Laser soldering has a number of unique advantages over traditional soldering techniques:

<!--[if !supportLists]-->·<!--[endif]-->High precision: The laser is able to focus into the micron welding area, making it suitable for handling small and complex components.

<!--[if !supportLists]-->·<!--[endif]-->Non-contact welding: Laser welding does not require direct contact with the surface of the material, so no mechanical pressure is applied, making it particularly suitable for temperature-sensitive or fragile components.

<!--[if !supportLists]-->·<!--[endif]-->Rapid heating and cooling: The heat input of laser welding is very concentrated, allowing for rapid heating and cooling, thus reducing the thermal impact on the surrounding components.

<!--[if !supportLists]-->·<!--[endif]-->Controllable: The welding temperature and energy output can be precisely controlled with the help of a closed-loop system to ensure the stability and consistency of the welding process.

Laser soldering is widely used in electronic device assembly, semiconductor packaging, circuit board soldering, and other applications that require high-precision soldering.

Laser soldering is a process that uses the high energy density of a laser beam to heat and melt tin solder for soldering. The laser has characteristics such as high brightness, high directivity, and high monochromaticity, and is able to precisely focus on a very small area, generate extremely high temperatures, and instantly heat the tin solder to a molten state while the surrounding material is almost unaffected, enabling high-precision soldering.

The difference between laser soldering and soldering iron

<!--[if !supportLists]-->·<!--[endif]-->Differences in welding methods

Soldering iron soldering usually adopts contact soldering, which is easy to scratch the surface of the product, and the soldering iron tip will exert a certain pressure on the welding workpiece during the soldering process, resulting in sharp solder joints and conduction risks. In contrast, laser soldering uses non-contact laser welding, which is better able to avoid these risks without causing mechanical damage to the product and without putting pressure on the soldered components.

<!--[if !supportLists]-->·<!--[endif]-->Differences in welding adaptability

When welding some workpieces with complex surfaces, the components on the surface of the workpiece are easy to interfere with the soldering iron tip and wire feeding device because the soldering iron tip and wire feeding device occupy a large space. The wire feeding device of laser soldering occupies a small space and is not easy to be disturbed. In addition, the spot size of the laser soldering lens can be adjusted, which can adapt to different sizes and types of solder joints to meet more product needs, while the traditional soldering iron soldering equipment needs to replace or redesign the soldering iron tip, so the adaptability of laser soldering is stronger.

<!--[if !supportLists]-->·<!--[endif]-->Differences in the effects of soldering on components

In the process of laser soldering, the laser only heats the part irradiated by the light spot, and the local temperature rises rapidly, which can effectively reduce the impact on the devices around the solder joint.

<!--[if !supportLists]-->·<!--[endif]-->Differences in energy-consuming materials

From the perspective of saving materials, most of the soldering iron tips are relied on to provide the required energy in the soldering iron welding process, but with the aging and wear of the soldering iron tip, the temperature will not meet the welding requirements, and the contact soldering method will make the soldering iron tip wear and tear seriously, and it needs to be cleaned and replaced frequently, thereby increasing the welding cost. From the perspective of energy saving, because the heating method of the traditional electric soldering iron welding process is conduction diffusion heating, it will cause more meaningless heat loss and increase the loss of electric energy.

<!--[if !supportLists]-->·<!--[endif]-->Differences in welding accuracy

Due to the limitations of the traditional electric soldering iron welding process and control methods, the wire feeding and welding accuracy are limited; Laser welding technology has the characteristics of rapid heating and rapid cooling, which can make the metal compounds produced during welding more uniform and fine, and the mechanical properties of the solder joints are better. Local heating is more conducive to soldering heated components and heat-sensitive components on circuit boards with dense components and solder joints, and can reduce the bridging between solder joints after soldering.

<!--[if !supportLists]-->·<!--[endif]-->Safe and controllable differences

The non-contact laser welding method reduces the risk of rosin and flux residues, reduces the generation of harmful fumes and waste, can accurately control the temperature of the solder joint in real time, prevents product defects caused by excessive temperature, and greatly reduces the difficulty of debugging the welding process and reduces the injury to operators.

Why choose semiconductor lasers as the light source of laser soldering systems With the improvement of IC chip design level and packaging technology, SMT is developing in the direction of miniaturization with high stability and high integration, and traditional soldering iron soldering can no longer meet its production technology requirements. The number of pins in a single component is increasing, and the pin spacing of integrated circuit QFP components is also shrinking, and it is moving in the direction of becoming more sophisticated. As a new welding process to make up for the shortcomings of traditional welding methods, non-contact laser soldering process is gradually replacing traditional soldering iron welding with its advantages of high precision, high efficiency and high reliability, which has become an irreversible trend.

The laser light source used in the laser soldering process is mainly semiconductor light source, which can be selected in the near-infrared or blue light band, with good thermal effect, and the uniformity of the beam and the continuity of the laser energy have a significant impact on the uniform heating and rapid heating of the pad, and the welding efficiency is high.

Diode lasers work by means of excitation, using electrons in semiconductor materials to jump between energy bands to emit light. The cleavage plane of the semiconductor crystal is used to form two parallel mirrors as mirrors, and a resonator is constructed to make the light oscillate, feedback and amplify in it, so as to generate and output laser light.

The basic structure of a semiconductor laser belongs to the PN junction of a semiconductor, but a laser diode has a "double heterojunction structure" in which a light-emitting layer (active layer) is sandwiched from both sides using layers of semiconductor material with different bandgaps. In addition, in laser diodes, the cleavage plane of the crystal is used as a mirror (resonator). The materials used include gallium (Ga), arsenic (As), indium (In), and phosphorus (P). In multi-quantum well structures, aluminum (Al) and other elements are also used.

The advantages of laser diodes include high efficiency, small size, light weight, and low price. In particular, the efficiency of the multi-quantum well structure is 20 - 40%, and the high energy efficiency is its biggest feature. In addition, its continuous output wavelength range covers infrared to visible light, and the light pulse output can reach 50W (100ns pulse width), which makes it ideal for laser soldering applications.

The role of closed-loop temperature control in laser soldering systems

<!--[if !supportLists]-->·<!--[endif]-->Real-time monitoring and feedback

The temperature closed-loop control system uses a high-speed infrared sensor to monitor the temperature of the solder joint in real time, and transmits the temperature data to the laser controller to realize real-time monitoring of the welding process.

<!--[if !supportLists]-->·<!--[endif]-->Precise temperature control

Through real-time data feedback, the laser controller is able to precisely adjust the output energy of the laser to ensure that the solder joint temperature is kept within the set range, thereby improving weld quality and consistency.

<!--[if !supportLists]-->·<!--[endif]-->Prevent overheating damage

If the temperature rises too quickly, the closed-loop control system can react quickly to reduce the laser energy or cut off the laser output, preventing damage to the device leads or soldering parts due to overheating.

<!--[if !supportLists]-->·<!--[endif]-->Improve the quality of welding

By precisely controlling the temperature and laser energy, the closed-loop control system can effectively reduce welding defects, such as burns, virtual welding, cold welding, etc., to ensure welding strength and reliability.

<!--[if !supportLists]-->·<!--[endif]-->Automation and intelligence

The temperature closed-loop control system combined with the CCD image monitor can automatically record and analyze the data in the welding process, providing a reliable basis for quality monitoring and production optimization, and improving production efficiency and product quality.

<!--[if !supportLists]-->·<!--[endif]-->Flexibility and adjustability

The closed-loop control system can flexibly adjust the laser energy and process parameters according to different welding tasks and material requirements, and adapt to various complex welding scenarios.

Neufeld Electronics laser soldering system is composed of multi-axis servo module, real-time temperature feedback system, CCD coaxial positioning system and semiconductor laser; After years of welding process exploration, Neufeld Electronics has independently developed intelligent soldering software, which supports the import of a variety of format files. The original PID online temperature adjustment feedback system can effectively control the constant temperature welding to ensure the welding yield and precision. This product has a wide range of applications and can be used for in-line production or independent processing. It has the following characteristics and advantages:

<!--[if !supportLists]-->1.<!--[endif]-->Non-contact welding is adopted, no mechanical stress damage, and the influence of thermal effect is small.

<!--[if !supportLists]-->2.<!--[endif]-->Multi-axis intelligent working platform (optional) can cope with a variety of complex and precise welding processes.

<!--[if !supportLists]-->3.<!--[endif]-->The coaxial CCD camera positioning and processing monitoring system can clearly present the solder joints and correct the alignment in time to ensure the processing accuracy and automatic production.

<!--[if !supportLists]-->4.<!--[endif]-->The original temperature feedback system can directly control the temperature of the solder joint, and can present the welding temperature curve in real time to ensure the yield of welding.

<!--[if !supportLists]-->5.<!--[endif]-->Laser, CCD, temperature measurement, and indicator light are four-point coaxial, which perfectly solves the problem of multi-optical path overlap in the industry, and avoids complex debugging.

<!--[if !supportLists]-->6.<!--[endif]-->Under the condition of ensuring the excellent rate of 99%, the minimum diameter of the welded solder joint can reach 0.2mm, and the welding time of a single solder joint is shorter.

<!--[if !supportLists]-->7.<!--[endif]-->The X-axis, Y-axis, and Z-axis are suitable for the welding of more devices, and are more widely used.

In the aerospace sector, laser soldering also plays an important role. Due to the extremely high performance and quality requirements of materials in the aerospace industry, laser soldering is able to meet these requirements and achieve high-quality welding. For example, in aero engine manufacturing, laser soldering can be used to weld superalloy materials to ensure the reliability and safety of the engine.

In the field of automobile manufacturing, laser soldering also has a wide range of application prospects. With the continuous development of automotive electronic technology, the number of electronic components in automobiles is increasing, and the requirements for welding technology are getting higher and higher. Laser soldering can meet the welding needs of automotive electronic components and improve the performance and quality of automobiles.