A Pick-and-Place Process Control Based On the Bootstrapping Method for Quality Enhancement in Surface Mount Technology

AbstractSurface Mount Technology (SMT) is a technique in electronic manufacturing to assemble electronic components on the surface of printed circuit boards. The industry has faced new challenges because of the increasing complexity of the assembly process to satisfy requirements such as lightweight, smaller size, and diverse configurations. With the usage of lead-free solder and the trend toward miniaturization in the electronics industry, the misalignment of solder paste has become more problematic. As the size of components decreases, it becomes more challenging to guarantee accurate placement and alignment during the assembly process. Self-alignment is a physical phenomenon during soldering, where components attached to soldered pads experience movement. Self-alignment can enhance the assembly quality by adjusting component positions near the desired position. However, it can lead to assembly defects, such as poor attachment and tombstoning, as components are shifted away from the pad center, resulting in an unbalanced position. Therefore, understanding and correctly using self-alignment becomes significant in modern electronic manufacturing. This research proposes a model that collects data from inspection to estimate the self-alignment strength and find a new placement location that can reduce component misalignment and enhance dimensional requirements for PCB assembly, such as side overhang and end overlap.