Hard alloy is generally used for drill bits for PCB drilling, because epoxy glass cloth copper clad laminates wear tools very fast.  Hard alloy is made by pressing and sintering tungsten carbide powder as matrix and cobalt powder as binder.  Usually it contains 94% tungsten carbide and 6% cobalt.  Due to its high hardness, wear resistance and certain strength, it is suitable for high-speed cutting.  However, the toughness is poor and very brittle. In order to improve the performance of hard alloy, some adopt chemical vapor deposition of a layer of 5-7 micron ultra-hard titanium carbide (TIC) or titanium nitride (TIN) on the carbonized substrate to make it have higher hardness.  Some use ion implantation technology to inject titanium, nitrogen and carbon into the matrix to a certain depth, which not only improves the hardness and strength, but also allows these injected components to move inward when the drill bit is regrinded.  In addition, a layer of diamond film is formed on the top of the drill bit by physical methods, which greatly improves the hardness and wear resistance of the drill bit.  Hardness and strength of hard alloy are not only related to the ratio of tungsten carbide to cobalt, but also to the particles of powder.  The average grain size of tungsten carbide phase for ultra-fine hard alloy drill bits is less than 1 micron.  The drill bit not only has high hardness, but also has improved compressive strength and bending strength.  In order to save costs, many drill bits now adopt welded shank structure, the original drill bit is made of hard alloy as a whole, and now the drill shank at the rear is made of stainless steel, which greatly reduces the cost. However, due to the adoption of different materials, its dynamic concentricity is not as good as that of the whole hard alloy drill bit, especially in the aspect of small diameter.