Due to the severe wear of micro drill and the difficulty in controlling of hole quality, high speed drilling process of high frequency printed circuit board (PCB) was attracted comprehensive attention. In this investigation, the wear width of drills’ primary face was measured, and the wear morphologies of micro drills were studied at once. Furthermore, regularity of micro hole quality concerning drilling burr and nail heading while drilling with different types of drills were analyzed. The research results indicated that the wear width of diamond coating drill reduced slightly. Abrasive wear and adhesive wear were mainly occurred on uncoated drill and diamond like carbon coating drill, but some micro breaches and pits appeared on uncoated drill. Meanwhile, drilling with diamond like carbon coating drill could obtain better hole quality than drilling with uncoated ones. However, diamond coating drill performed well in terms of ability of wear resistance, as well as micro hole quality.

High frequency printed circuit board (PCB), as the significant support for 5G technology, has been receiving intense attention from the increasing number of scholars. Concerning precision fabrication of high frequency PCBs, micro hole drilling is deemed as one of the extremely crucial challenges. In this study, the coated drill bits’ wear and micro hole quality were investigated through the drilling experiments of high frequency PCBs. Results showed that two kinds of coated drill bits exhibited well in terms of hole registration accuracy. Using diamond like carbon coated drill bits could obtain fewer burrs than drilled with diamond coated drill bits before drilling 200 holes, but the burr height increased very slowly with the increment of hole number when using diamond coated drill bits. Taking the combination of aluminum sheet and phenolic aldehyde board as the entry board was conducive to obtaining less burr, and the micro drill bits with helix angles of 40° and 42° were contributed to achieving less burr too. Additionally, decreasing the feed rate could lessen the hole blocking.

Drilling force directly affects the micro drill life and micro hole quality in the micro hole drilling of printed circuit board (PCB). But in the micro hole drilling process, the signal-to-noise ratio (SNR) of drilling force signal is low. Drilling force signal often submerged by noise signal, these brings great difficulty to measurement during PCB drilling process. Therefore, it is urgent to improve the SNR of drilling force signal in PCB drilling process. The observed signal of drilling force is obtained by PCB micro hole drilling experiment. Based on the cyclostationary and time domain accumulation theory, the drilling force signal is quadratic filtered, and the filtering effect of the filter on the drilling force signal is evaluated. In this paper, a composite multiple filter is designed to improve the SNR of drilling force signal rapidly and efficiently (SNR increased by 11.76 dB), realize the accurate description of the PCB micro hole drilling process.

No abstract

High-speed circuit boards are created to meet the high-speed signal transmission requirements of 5G communication technology, but the non-polar resins, at glass bers, and multiple and hard llers 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 ultrasonicassisted 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 in uence 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 veri cation 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 in uence 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.