Coupling mechanism and optimization of THT assembly process parameters based on flexible soldering robot platform

Abstract

In this study, the through-hole technology (THT) assembly process and the basic soldering principle of automated flexible soldering robot are investigated, and the critical soldering process parameters such as soldering temperature, soldering time and solder feeding volume which have great influence on the soldering quality are proposed. The evaluation method of the soldering quality is also determined. Then, taking into account the coupling relationship between process parameters, the process parameter experiments are designed using the response surface method. Meanwhile, the polynomial empirical model reflecting the relationship between critical process parameters and soldering quality comprehensive score is established. On this basis, the coupling influences mechanism between the critical soldering process parameters on the soldering quality is analyzed, and the four-dimensional (4D) slice map of the coupling influence of the process parameter on the soldering quality is obtained. Finally, based on 4D slice map, the three-dimensional (3D) process window of the soldering process is developed to optimize the critical soldering process parameters, and the verification tests are implemented to verify the stability and reliability of the 3D process window. The study results show that for the PCB solder joints of this experiment, the optimal 3D process window of the soldering process parameters is about: soldering temperature within [350 ℃, 380 ℃], soldering time within [1.3 s, 1.55 s] and solder feeding volume within [1.7 mm3, 2.3 mm3], respectively. Using the combination of process parameters in this 3D process window for robot soldering, the quality comprehensive score will reach more than 90 points.