High precision PCB Soldering With Pin Springback Compensation by Robotic Micromanipulation

Through-hole components (THCs) soldering is widely reserved in electronic industry. Although recent progress in soldering robot has greatly improved the productivity, how to deal with metal pins' misalignment with the through-hole center remains a big issue, which may affect the soldering quality, reduce the product reliability, or even result in failure. To address this challenge, this article presents a robotic micromanipulation system and a hybrid visual servoing control strategy with springback compensation. First, we analyze the deformation and recovery phenomenal of the metal pin during alignment and then establish its elastoplastic model and springback model accordingly. In view of high precision and efficiency in electronics assembly, we propose a hybrid control strategy by combining the position-based and image-based visual servoing control, where the former is for approaching the target region efficiently and the latter is for high precision pin alignment. With the developed model and control strategy, the robotic micromanipulation system can automatically detect the pin's position and posture by a microscope camera (magnification 15${\times }$) and control the end-effector to align the pin to the through-hole center based on a predicted overshoot. The experimental results verify that our approach can confine the maximum alignment error in three pixels ($\sim$37 ${\mu }$m) with 100% success rate, which substantially improves the soldering accuracy of current techniques. This article paves a new path for high precision THCs soldering, which will not only directly improve the quality and reliability of PCBs in industry, but also inspire the application of robotics in micromanufacturing and microfabrication.