The Mechanism Analysis And Experimental Study Of Laser Molten-tin Soldering Based On Laser Processing Technology

As a new technology in the welding field, the soldering technology has played a major role in the field of electronic packaging, especially in the microelectronics precision packaging and machining. With the improvement of IC (Integrated Circuits) chip designing and manufacturing level, the SMT (Surface Mounting Technology) is developing towards the direction of high reliability, high integration and miniaturization. So the traditional welding methods have been unable to meet the technical requirements. Due to the increasing number of single component pins, at present the single component can reach more than 576, and the pin center distance has been reduced to 0.3 or less. So that the ’bridge’ defects, between adjacent lead solder joints, are easy to appear in the hot air reflow soldering, vapor phase reflow soldering, infrared reflow soldering and other traditional welding methods. Non contact laser molten-tin soldering technology for the high precision, high efficiency, high reliability and other advantages, is gradually occupying the microelectronic packaging market. Such as heat sensitive components, PCB board, heat sensitive parts besides the very fine coaxial line and solder, stacked welding of electronic connectors and spot welding.In this paper, according to the technology requirement of the microelectronic packaging development, system analysis the welding principle of the laser molten-tin soldering. Choose more stable performance of semiconductor laser as a heat source, and apply the principle of aerodynamics and cylinder movement, then design a conveying system which can achieve a smooth transportation of single ball. Based on the above research design a laser molten-tin soldering device, and create a prototype. Then study on the principle analysis and experimental results of the core subsystems of laser molten-tin soldering device.This paper first makes a theoretical analysis of the heat source part of laser molten-tin soldering device, namely the luminescence characteristics of semiconductor laser, and how to coupling the energetic laser beam with optical fiber and then transport to the designated location. Different diameter was established by analyzing the mathematical model of solder balls with laser energy. Secondly, analyzes the characteristics of gas in the flow passage, And solder balls in the mechanics mechanism of the nozzle. According to this theory, design different specifications of the groove plate and nozzle. Use FLUENT fluid simulation software to analyze the gas flow state in groove plate and nozzle, and the state of motion of the molten tin ball in different gas pressure.According to the simulation results calculates the structural parameters of tin balls arranged groove plate and the optimum state of structure parameters when the tin balls drop.Then, describe the structure and working principle of the laser molten-tin soldering device, and analyze the mechanism of double acting cylinder in the organization. At the same time, also introduce the each subsystem of the laser molten-tin soldering device in brief, describing the function and the way of realization.Finally, relevant experimental study on the laser molten-tin soldering experiment platform is started. Through the analysis of a large number of experimental data, determine the laser power, laser light time, the sending material and intermittent time of tin balls, the flow size and other influent welding performance factors. And build the stability test of the constructed prototype, also detect the reliability welding effect.