Papers by Keyword: Printed Wiring Board

Abstract: There have been few reports dealing with the drilling of printed wiring boards (PWBs) with micro-drills that are smaller than 0.2 mm in diameter, and super-high-speed spindles that are higher than 160,000 rpm. In these cases, preventing the micro-drill from breaking and keeping the position accuracy of the drilled hole has been difficult. We therefore focus on the high-speed step-drilling method and short stroke as a novel way of resolving these problems. On the other hand, determining the complicated combination of feed speed, rapid feed speed, and stroke length is difficult. Under these backgrounds, in this report we propose a fast-feed step cycle that use fast-feed command without the processing feed. Thus, we attempted to apply the response surface method to optimize these parameters. As a result, a proposed method was found to be effective to improve the drilled hole quality and drilling efficiency in such kinds of micro-drilling of the PWBs.

Abstract: A drilling technique using micro-drills of 0.2 mm or less in diameter and a super-high-speed spindle of 160000 rpm or more has been developed for drilling ultra-micro holes in printed wiring boards (PWBs). The drilling process requires higher reliability and quality to maintain the reliability of the electrical connection between circuit layers. On the other hand, higher processing efficiency is also required in PWBs manufacturing. To maintain high productivity, drilling is normally performed using a non-step method, but heat damage called B-RING occurs around the drilled holes with this method. To solve these problems without the loss of processing efficiency, we applied the rapid-feed step-drilling cycle method. We investigated the B-RING for drilling quality and evaluated the drilling time for processing efficiency under various drilling conditions. We found that using a rapid-feed step-drilling cycle with an appropriate number of steps and feed rates ensures a higher level of hole quality and processing efficiency compared with the conventional non-step drilling.

Abstract: 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.