In essence, laser drilling is a kind of thermal processing method that focuses the laser beam on the workpiece and changes the light energy into heat energy. It is the action process of laser pulse radiation with certain energy density on the workpiece material. After focusing, the laser is used as a high-intensity heat source to heat the material, which makes the material melt or vaporize in the laser action zone, and then evaporate to form holes.
Laser drilling is very good, only one is not reliable.
That is, when laser drilling, the material on the workpiece should be as uniform as possible, because different materials have different absorption of laser energy. If the material is not the same, it will lead to long and short time consuming in laser cauterization. PCB is composed of many kinds of materials after pressing, such as metallized holes on PCB, copper in the holes and substrate around the holes. In laser processing, copper needs more energy than substrate.
The figure below is a slice of the hole. The hole copper is surrounded by resin and fiberglass cloth.