In processing the tiny hole on printed circuit board precision is effected by the tiny diameter of the solid drill, its poor rigdity and excessive difference between locations of the inlet and the outlet of the drill. 在印刷电路板的微孔加工中,因钻头的直径很小,刚性较差,钻孔的出口与入口位置偏差过大,而影响微孔加工的精度。