Thermal Damage of Micro Diameter Hole Drilled by Super-High-Speed Spindle in PWB

Recently, a new drilling technology has been attracting attention using a super-high-speed spindle and micro diameter drills (less than 0.2 mm). In these drilling conditions, B-RING damage extends more than internal damage around the drilled holes. Therefore, we investigated the best drilling conditions for control of the B-RING, considering productivity. The following conclusions were obtained. (1) The temperature of the drilling tool is raised by decreasing the heat capacity of the drill. B-RING damage around the drilled hole is especially generated under drilling conditions using the super-high-speed spindle and micro diameter drill. (2) B-RING is mainly caused by the heat being conducted to the hole wall of the PWB. (3) Raising the R point height is an effective method for preventing B-RING damage. (4) We confirm obtaining the best drilling condition by considering B-RING and productivity.