Nowadays, with the rapid updating of electronic products, the printing of PCB s has expanded from the previous single-layer boards to double-layer boards and multi-layer boards with higher precision requirements. Therefore, there are more and more requirements for the processing of circuit board holes, such as: the hole diameter is getting smaller and smaller, and the distance between the hole and the hole is getting smaller and smaller. It is understood that the board factory currently uses more epoxy resin-based composite materials. The definition of the size of the hole is that the diameter is less than 0.6 mm for small holes and 0.3 mm for micropores. Today I will introduce the processing method of micro holes: mechanical drilling.
In order to ensure higher processing efficiency and hole quality, we reduce the proportion of defective products. In the process of mechanical drilling, two factors, axial force and cutting torque, must be considered, which may directly or indirectly affect the quality of the hole. The axial force and torque will increase with the feed and the thickness of the cutting layer, then the cutting speed will increase, so that the number of fibers cut per unit time will increase, and the tool wear will also increase rapidly. Therefore, the life of the drill is different for holes of different sizes. The operator should be familiar with the performance of the equipment and replace the drill in time. This is why the processing cost of micro holes is higher.
In the axial force, the static component FS affects the cutting of Guangde, while the dynamic component FD mainly affects the cutting of the main cutting edge. The dynamic component FD has a greater influence on the surface roughness than the static component FS. Generally, when the aperture of the prefabricated hole is less than 0.4mm, the static component FS decreases sharply with the increase of the aperture, while the trend of the dynamic component FD decreases is flat.
The wear of the PCB drill is related to the cutting speed, feed rate, and the size of the slot. The ratio of the radius of the drill bit to the width of the glass fiber has a greater impact on the tool life. The larger the ratio, the larger the width of the fiber bundle cut by the tool, and the increased tool wear. In practical applications, the life of a 0.3mm drill can drill 3000 holes. The larger the drill, the fewer holes are drilled.
In order to prevent problems such as delamination, hole wall damage, stains, and burrs when drilling, we can first place a 2.5 mm thickness pad under the layer, place the copper clad plate on the pad, and then Put the aluminum sheet on the copper clad board. The role of the aluminum sheet is 1. To protect the board surface from scratches. 2. Good heat dissipation, the drill bit will generate heat when drilling. 3. Buffering effect / drilling effect to prevent deviation hole. The method of reducing burrs is the use of vibration drilling technology, using carbide drills to drill, good hardness, and the size and structure of the tool also need to be adjusted