Interaction of cemented carbide micro-drills and printed circuit boards during micro-drilling

Cemented carbide micro-drills (0.1 to 0.3 mm in diameter) wear down or break casually while drilling microholes in printed circuit boards (PCBs). This study focused on the interaction between cemented carbide and PCB and its effects on PCB micro-drilling. The results indicated that two-body abrasive wear and three-body abrasive wear occurred on the flank face and the chisel edge of micro-drills. Heat generated during friction softened the resin from PCB and friction chips, which were then pressed to cover the surface of cemented carbide and filled the grooves on the surface. The resin adhered to the flank face of micro-drills and made the wear rate of micro-drills slow down. However, the resin of the PCB can also adhere to the tip and the helix flute of micro-drills at high temperature, which may damage the chip removal during micro-drilling and the hole location accuracy.