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

Kam Chuen Yung, Anddle K Y Cheung

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review


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 technology sucessfully in printed circuit board industry. By using same laser energy, better hole size and shape was achieved by oxide replacement process (Multibond) which showed higher surface roughness Ra, 0.5606um and grain structure among the oxide surface treatments in this study. It was found that 5-7μm copper thickness was more suitable and achievable for controlling micro-via hole size and shape in CO2 copper direct laser drilling.
Original languageEnglish
Title of host publicationPICALO 2004 - 1st Pacific International Conference on Applications of Laser and Optics, Conference Proceedings
Number of pages6
Publication statusPublished - 1 Dec 2004
EventPICALO 2004 - 1st Pacific International Conference on Applications of Laser and Optics - Melbourne, VIC, Australia
Duration: 19 Apr 200421 Apr 2004


ConferencePICALO 2004 - 1st Pacific International Conference on Applications of Laser and Optics
CityMelbourne, VIC

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Electrical and Electronic Engineering

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