Novel drilling technique in polyimide using visible laser

We report a new and fast laser-drilling technique in polyimide. This drilling process consists of two steps. First, the polyimide is irradiated with millisecond pulse of visible laser light. Second, the debris inside and around the holes are ultrasonically cleaned in water in a short time. In this report, we also analyze the emitted light originated from the laser induced polyimide decomposition that leads to the drilling. The mechanism behind the drilling is believed to be associated to a volcano-eruption-like behavior. This inexpensive technique provides good quality drilling, high throughput, and very promising applications in packaging technology.