Wear mechanisms of micro-drills during dry high speed drilling of PCB

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• 作者：L.J. Zheng ; C.Y. Wang ; L.Y. Fu ; L.P. Yang ; Y.P. Qu ; Y.X. Song
• 关键词：Micro hole ; Drilling ; PCB ; Wear mechanism ; Cutting parameters
• 刊名：Journal of Materials Processing Technology
• 出版年：2012
• 出版时间：October, 2012
• 年：2012
• 卷：212
• 期：10
• 页码：1989-1997
• 全文大小：1979 K

文摘

In this paper, micro-drills with diameters of 0.1-0.3 mm were used to drill printed circuit boards (PCBs) with a highest spindle speed of 300 krpm. To study the wear mechanisms of PCB micro-drills, micro-drill morphology was observed, and the flank wear of the micro-drills was measured. The factors affecting flank wear were studied. In addition, hole wall roughness, nail head formation, and the accuracy of hole location were measured and analysed to determine how micro-drill wear influenced hole quality. It was found that abrasion was the main mechanism controlling the deterioration of cemented tungsten carbide micro-drills. The aggressive rubbing by glass fibre broken chips and reinforcing fillers, and the diffusion of cobalt caused abrasive wear of the flank, the chisel edge, the rake face, and the minor flank of the micro-drills. Resin that was softened by cutting heat would adhere to the micro-drills, which decreased chip removal and the accuracy of hole location. Micro-drill wear was inclined to cause nail heads and decrease the accuracy of hole location.