Micro drills as a supplement to laser drilling

One processing method, currently common, for circuit boards with high packing densities and micro holes is laser drilling, carried out at very high speed. The micro drills, with diameters less than 0.1 mm offered by MPK Kemmer PCB Tools, represent a good alternative to this drilling process.

"We do not think that laser drilling can be replaced by conventional drilling using helical bits, but we want to offer a functioning alternative", says Theo Martens, Manager of Application Technology at MPK Kemmer PCB Tools. He illustrates this by pointing at the same time to a number of vital differences between the two methods: laser drilling depends heavily on the material. It is less suitable, for instance, for circuit board materials incorporating glass fibre.

This is not true for micro drills. According to Martens, they are suitable for all the circuit board materials in use, such as BT resin systems, high-Tg resins, aramide, polyimide and thick copper with appropriate drilling depths. In addition to this, the particular strength of laser drilling machines is in the manufacture of blind holes, and the investment and operating costs are higher than those of multi-spindle CNC drilling machines.

The drive for the development of these micro-drills came from the electronics industry. New applications, new materials, new drill geometries, and increasing cost pressure in the circuit board tool sector – these were the critical factors. The development of spindles with rotation speeds above 180,000 rpm provide the technical preconditions for using these micro-tools efficiently.

Modern production methods with extremely tight tolerances allow undercut/spade micro-drills to be manufactured with diameters starting at 0.11 mm, and micro drills with diameters from 0.05 mm upward. Martens adds that while precision is comparable, the quality of the drilled holes is better than that of those burnt by laser.