Study on the mechanism affecting the quality of micro-hole in ultrasonic-assisted drilling of high-speed circuit boards

Abstract

High-speed circuit boards are created to meet the high-speed signal transmission requirements of 5G communication technology, but the non-polar resins, flat glass fibers, and multiple and hard fillers used for this purpose have launched new challenges to their micro-hole processing. Micro-hole quality has always been a decisive factor in board performance, therefore, this paper proposes a new processing method for improving micro-hole drilling quality of high-speed circuit boards, establishes an ultrasonic-assisted drilling tool motion model. Then, this paper analyzes the changes in drilling method, material deformation, chip breakage and chip removal during ultrasonic-assisted drilling of printed circuit boards, to study the influence mechanism on micro-hole quality during ultrasound-assisted drilling. In addition, an experimental platform for ultrasonic-assisted drilling is designed and built, and single-factor experiments for verification of ultrasonic effects, optimization of drilling parameters, and orthogonal experiments for ultrasonic-assisted drilling of high-speed circuit boards are conducted on this platform. The experimental results show that the loading of ultrasonic vibration has a very obvious improvement on the situation of several machining defects such as hole wall roughness, entrance burr and nail head in micro-hole drilling of high-speed circuit boards. In addition, the influence order and better level combination of each processing parameter are obtained, which provides a theoretical research basis and processing instructions for the improvement of micro-hole quality of high-speed circuit boards.