With the improvement of product performance, PCB are constantly updated and developed. The circuits are becoming denser and more and more components need to be placed. However, the size of the PCB will not become larger, but smaller and smaller. At this time, if you want to drill holes in the plate, you need considerable skills.
There are many PCB drilling techniques. The traditional method is to make inner blind holes. When laminating multilayer boards successively, first use two double-sided boards with through holes as the outer layer and press them with the non-porous inner board. Then there are blind holes filled with glue, and the blind holes on the outer board surface are formed by mechanical drilling. However, when making machine-drilled blind holes, it is not easy to set the drilling depth of the drill bit, and the bottom of the tapered hole affects the effect of copper plating. In addition, the process of making inner blind holes is too long and wastes too much cost. Traditional methods are more and more unsuitable.
Nowadays commonly used PCB micro-hole technology, in addition to the carbon dioxide drilling and laser drilling we introduced before, there are mechanical drilling, photosensitive drilling, laser drilling, plasma etching and chemical etching.
Mechanical drilling is made by high-speed machining. The most important one is the drill bit. The drill bit is generally made of tungsten-cobalt alloy. The alloy is made of tungsten carbide powder as the matrix and cobalt as the binder. With high hardness and high wear resistance, you can smoothly drill the holes.
Laser hole is made by carbon dioxide and ultraviolet laser cutting. The gas or light forms a beam of light, which has powerful heat energy and can burn through the copper foil to create the required hole. The principle is the same as cutting, mainly to control the beam.
PDP is also plasma. The particles that make up the plasma have a large distance between them and are in constant and random collisions. Its thermal motion is similar to that of ordinary gas. Plasma etch holes are mainly used for PCBs with resin copper layers. Oxygen-containing gas is used as plasma. After contact with copper, an oxidation reaction will occur, and the resin material will be removed to form holes.
As mentioned before, the remaining objects on the PCB cannot be cleaned by normal methods. Chemical cleaning methods can be used to make the chemical agents react with the residues to be removed. It is the same as drilling. Use chemical agents and drop them on the place where drilling is needed to erode the copper foil, resin, etc., and finally form holes.
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