laser-assisted plating of printed circuit board (PCB) microvias
Background of Research
This research project aims to investigate the laser-assisted plating process of printed circuit board (PCB) microvias. The UV YAG laser used in this study is of short duration pulses and operates in the ultraviolet spectrum at 355nm wavelength where the laser beam is highly absorbed by copper. It is capable of ablating the top layer copper, as well as inner layer dielectric. The ablation process causes rapid vaporization that results in ejecting micron and submicron particles of copper from the bottom layer of blind via to splatter against the internal hole wall surface. The dynamics of the process result in evenly distributed copper particles impacting and slightly imbedding themselves on the side walls of the via, creating a smooth and vigorously attached conductive layer which has a significant bonding strength to the dielectric materials. Thus, it eliminates conventional electroless copper process step and hence effectively reduce cycling time and cost.
Objective
1. To investigate the deposition process of a thin copper film/layer on PCB microvias dielectric (glass/epoxy).
2. To study the relationship of different processing parameters in optimizing the laser-assisted plating process.
3. To evaluate the quality and reliability of laser-plated microvias.
