1. Prevent burrs and scratches on the surface of PCB board.

　　2, heat dissipation and drill cleaning function.

　　3, can guide the drill into the track of the PCB board to improve the accuracy of drilling.

　　Aluminum sheet requires a large thermal conductivity, so that the heat generated during drilling can be quickly taken away, reduce the temperature of the drill, should try to use 0.15-0.2mm thick aluminum sheet or 0.15-0.35mm aluminum alloy composite aluminum sheet, effectively prevent drilling due to the high temperature caused by poor drilling chip removal and resulting in broken drill.

　　3, the quality of the copper clad sheet material, the glass fiber cloth of the sheet material is thick, the binding force is not good, and it will also have a greater impact on the drill break. If the resin polymerization of the plate is not complete, it is easy to produce more glue residue of the hole wall, poor chip discharge and broken drill. If there are holes in the substrate, the drill nozzle will be broken under uneven force during drilling. Therefore, the sheet must be baked before drilling. The baking time is generally 4 hours /150oC±5oC

　　4, the use of drill drill must be based on the processing purpose, product hole wall quality requirements, use to select different types of functions of the drill. The main categories of drill are 1: ST type (straight drill) 2:UC type (under cut drill) 3:ID type (inverse drill), the most commonly used is ST type, suitable for double panels containing paper, epoxy paper, phenol epoxy glass and other board materials and PCB boards below four layers. The characteristic of UC drill is that the diameter below the tip is smaller than the diameter above the head (that is, the head is large and the body is small), the design principle is to reduce the friction with the hole wall during the drilling process to prevent the hole wall from being too thick and broken. It is very important to choose a supplier with timely supply, stable quality and perfect after-sales service.