The drilling machine is a preprogrammed Computer Numerically Controlled (CNC) machine. The drill takes place based on the XY coordinates fed into the CNC system. The spindles rotate at a high RPM and ensure an accurate drill hole in the PCB. When the spindle rotates at a rapid speed, heat is generated due to the friction between the hole wall and the spindle. This melts the resin content on the hole walls and results in a smear of resin. Once the required holes are drilled the exit and entry panels are discarded. This is a small gist of what goes happens on the shop floor.
Unlike the etching and plating process, the drilling process doesn’t have a fixed duration. The drilling time varies on the shop floor depending on the number of holes to be drilled. This is what happens behind the curtains in the PCB manufacturing unit. To know more about computer-aided manufacturing as related to PCB read What is CAM or Computer-Aided Manufacturing?
Two significant aspects to be considered in the drilling process:
- The aspect ratio
- Drill to copper clearance (Drill to the nearest copper feature)