CO2 laser drilling of micro-via without conformal mask in PCB manufacture

In order to ensure that the laser remains at the forefront of micro-via forming in the future, many new laser technologies are being investigated by PCB manufacturers for high-density interconnect (HDI) printed circuit boards. As there were limitations of etching small micro-via size and registration in conformal masked laser drilling method, copper direct drilling by laser irradiation has been developed as an alternative. This research work was studied on the difference between several surface treatment processes for enhancing the laser absorptivity of copper, and reducing the thickness of the copper layer by chemical means in laser drilling technology. Also, the effect of critical laser drilling parameters and dielectric material properties were studied in this paper. It was shown that unreinforced and pure resin epoxy material was better in laser ablated microvia maufacturing. The laser absorptivity of copper and copper thickness were very critical factors for implementing copper direct laser drilling ...