Design and Experimental Evaluation of a High-Precision SCARA Robotic System for Underfill Dispensing in PCBA

The increasing complexity of printed circuit board assembly (PCBA) processes has driven the adoption of automated solutions aimed at improving quality, repeatability, and production efficiency. In this context, this paper presents the experimental development and functional validation of the Underfill N950U project, which focuses on the study, selection, and validation of technologies for automated underfill adhesive application in N950U PCBAs used in the Cal-Comp assembly line. The current manual underfill application process presents limitations related to adhesive volume variability, high ergonomic effort, operational risks, and low process repeatability.

The proposed solution replaces the manual operation with an automated system based on a SCARA-type robotic manipulator with a 600 mm reach, integrated with a high-precision dispensing system, motion control, and vision-assisted positioning. The project includes the development of an offline prototype intended for the comparative evaluation of different underfill application technologies, enabling controlled testing to determine optimal process parameters such as adhesive volume, application speed, repeatability, dimensional stability, and cycle time.

Based on time and motion analysis, the proposed architecture was designed to support an estimated production of 2,400 PCBAs per day, with an approximate cycle time of 2 minutes and 30 seconds per carrier, while ensuring serial-number traceability and compliance with industrial safety requirements, particularly NR-12. The expected outcomes include reduced process variability, improved ergonomics, increased productivity, and the consolidation of incremental technological advancements, contributing to enhanced digital maturity and overall manufacturing efficiency.