High speed laser formation of small diameter apertures in printed circuit board blanks

The formation process of small diameter apertures by the radiation of a CO2 laser in an epoxy based glass reinforced plastic used in the production of pc boards with layer thickness 0.15 mm is examined. The glass fraction of the substance has high infrared CO2 laser radiation absorption, improving the quality and effectiveness of laser drilling. Conditions of production of holes without metalization studied which met the requirements that laser drilling must be faster than mechanical drilling on two coordinate program controlled drilling machines (less than about 0.2 s). The focusing system for the laser beam was a two element lens designed for minimum aberration. Diagrams of hole shapes produced by various methods of operation are presented. The apertures formed by the laser pulses are well coated by chemical copper from solution and nickel from the gas phase, allowing them to be used as contact apertures in PC boards.