Through Hole Forming Method Using a Flowable Backing Material During Pulse UV Laser Radiation

This paper presents a unique through hole forming method using a flowable backing material during pulse UV laser radiation. During the laser radiation, the backing material such as polymer material solution is arranged to be in contact with the back side of a target material (workpiece), i.e., surface of laser beam's exit side. This unique through hole forming method can easily control the shape of a through hole, e.g., formation of a through hole having straight shape in which the exit hole diameter on the laser beam exit side of the processing target is equal to the entrance hole diameter on the laser beam incident side, or formation of a through hole having so-called inverse tapered shape where the diameter of a formed through hole on the laser beam exit side is larger than the incident side.