Placing laser-beam transparent plastic on top of non-transparent plastic and then exposing the laser beam makes it possible to take advantage of a phenomenon wherein the plastic heat-fuses on the surface of the non-transparent plastic.
Aside from superiority over conventional plastic fusing methods (e.g., ultrasound, heat plate, adhesion, etc.) in terms of working environment, this method also provides better appearance quality, air tightness, and other features.