EPTE Newsletter from Japan - Mechanical Drilling for Micro Holes
4th September, 2006
Union Tool, a large drill bit supplier for the NC drilling process of PWB manufacturing in Japan, talked about the drilling process and current technological trends. A spokesman for Union Tool stated that the technology trends for HDI circuit boards and IC substrates suggests the hole sizes have shifted to a smaller size in a short period of time.
Currently, about 65% of the drill bits are smaller than a 300 microns diameter (12 mils); an increase of 5 points in the last year. Diameters smaller than 150 microns (6 mils) represent 14% use, and popularity for this smaller size is growing quickly. Presumably, drill bits smaller than 200 microns could be the preferred choice within the next year or two. Diameters smaller than 100 microns are not widely used; however, they could become commonplace in the near future.
Drill bit manufacturers and NC drill machine companies are collaborating to develop a process to produce 50 microns holes. Have you seen the actual 50 micron diameter drill bit? It is smaller than a hair, and the throats are very short. It is unbelievable that this fine bit can drill glass epoxy boards.
Several years ago, we believed that mechanical drilling hit a technical barrier for microns with a diameter under 150, and laser drilling machines would take over the micro via business. It was true. Thousands of laser machines were sold to the Asian PWB manufacturers for build-up boards of IC substrates and cellular phones. A majority of them are carbon dioxide laser type because of high through put down to 50 micron diameters. Many UV-YAG laser and Excimer laser machines were also sold for holes with diameters finer than 50 micros; however, mechanical drilling machine companies and drill bit manufacturers did not abandon the business of micro via holes because they knew their customers liked mechanical drilling process. They have been successful with the micro via hole business for the HDI circuit boards over last few years.
Recently, ShinEi Techno, an engineering firm for a mechanical drilling process, developed an ultra fine drilling technology using special drilling bits. ShinEi said it could generate 20 micron diameter holes with 30 micron pitches on the 150 microns thick stainless steel and aluminum boards. This material is not used for circuit boards; however, it could suggest that the mechanical drilling is still competitive where ultra fine via holes and the laser drilling systems are used.
I do not think that all of the laser drilling systems will be taken over by the mechanical drilling systems. The mechanical systems are not suitable for all applications, and laser systems have a lot of advantages compared to mechanical systems; especially in the case of the blind via holes for build-up constructions. I can say that HDI circuit board manufacturers will have more choices for the micro via drilling process.
Hitachi Via Mechanics, a major equipment supplier in Japan is smart. Hitachi provides both mechanical and laser drilling machines and Hitachi has the lion share of the market with both drilling systems.