Investigation on Drill Wear and Micro Hole Quality in High Speed Drilling of High Frequency Printed Circuit Board

Abstract

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.

A review on the balancing design of micro drills

“…At present, substrate materials of micro drills in the market mainly include high-speed steel, cemented carbide, and PCD. Several literatures had introduced the above three materials, respectively, in detail [ 1 , 7 – 9 ]. The comparison of main mechanical properties of these three substrate materials is shown in Fig.…”

“…This leaves very limited room for chip evacuation and may cause chips entangled or even clogged in flutes of drills. Especially for PCBs, which belong to difficult-to-machine composite materials, the cutting condition is more complicated than other homogeneous materials like metal [ 1 ]. All these reasons result in micro drilling that behaves differently compared to conventional drilling.…”

“…Resin adhesion to helical flutes inevitably hinders chip evacuation in time, which may inevitably generate more friction and exert additional torque on micro drills [ 61 ]. To make matters worse, friction between the drill, workpieces, and chips increases temperature inside micro-holes, further softening epoxy resin and thus forming a vicious circle [ 1 ]. Under this case, the torque variation of micro drills is relatively unstable.…”

“…There are large requirements for micro-machining with higher manufacturing precision in fields such as aerospace, medical devices, and electronic information, as well as smaller and lighter personal consumption products which provide the convenient lifestyle. As an important part of micro-machining, micro-hole drilling accounts for more than 40% [ 1 ]. Although nowadays there have been numerous non-conventional machining techniques that have different processing principles such as laser machining, electrical discharge machining (EDM), electrochemical machining (ECM), and electron beam machining (EBM) [ 2 , 3 ], conventional mechanical micro drilling is still widely used due to its advantages of excellent processing quality, stable work, high versatility, and high material removal rate.…”

Prediction Model of the Remaining Useful Life of the Drill Bit during Micro-Drilling of the Packaging Substrate

“…When it comes to the tool life and health state, many studies focused on the change in tool wear [3][4][5][6][7][8], and researchers believed that the range of oscillation [9] and vibration signal [10] were practical to explore the service state of tools. While considering the influence of the wear status of cutting tools on axial drilling force, Tansel et al [11] presented a relationship model of axial force and tool wear in micro milling based on a BP neural network.…”