PCB printed circuit board drilling, the use of the upper and lower plate is to prevent the surface of the board and the bottom surface of the copper foil to produce burrs, so that the surface of the board drilling smooth improve the quality of the PCB printed circuit board, improve the yield. Due to the use of this auxiliary material has a certain cost, but due to the above reasons, it is in fact necessary to use, which can greatly improve the pass rate of the product and reduce the cost.

　　The requirements for the board drilling are: there is a certain surface hardness to prevent burrs on the surface of the drilling. But not too hard to wear the drill. It is required that the resin composition of the upper and lower backing plate should not be too high, otherwise a molten resin ball will be formed when drilling and adhere to the hole wall. The larger the thermal conductivity, the better, so that the heat generated during drilling can be quickly taken away, reduce the temperature of the drill when drilling the hole, and prevent the drill from annealing. It must have a certain rigidity to prevent the plate from shaking during drilling, and it must have a certain elasticity to deform immediately when the bit is in contact with the drill, so that the drill is accurately aligned with the position of the drill and the accuracy of the drilling position is ensured. The material should be uniform and there should be no impurities to produce uneven joints, otherwise it is easy to break the drill. If the surface of the upper plate is hard and slippery, the small diameter drill bit may slip away from the original hole position to drill elliptical diagonal holes in the board.