The importance of laser drilling is increasing as the use of HDI technology in PCB fabrication designs requires the use of microvias. These smaller sized holes require extremely precise and controllable depth drilling. This precision can be achieved using a laser. In this case, it is not possible to use mechanical drilling for the following reasons:

Mechanical drilling can cause the drill bit to vibrate.

It is not suitable for drill holes smaller than 6 mil in diameter.

Mechanical drilling is not suitable for precisely controlled depth drilling.

Mechanical drilling is expensive and time-consuming.

Mechanical drilling is an expensive and time-consuming process.

Since mechanical drilling involves manual selection of the right tool, the process can be fraught with manual errors. This can lead to costly restarts that affect the cost and time of the entire project.

Laser drilling, on the other hand, can drill vias as small as 2.5 to 3 mils in thin glass reinforcements. 1mil vias can also be drilled where there is no reinforcing dielectric.