What is the difference between a drill and a two drill in the PCB type?
PCB drilling is a process of PCB plate making, but also a very important step. The main board is to punch lines, to make a hole, make a hole in the structure to do what the multilayer board positioning; not a finished drilling, some buried hole in the circuit board, some of them get through the above board, so there will be a two diamond drill.
The two drill must be behind a drill, that is to say the process is separate.
The two hole is a hole that does not need to be sunk, such as a screw hole, a positioning hole, a heat sink, etc.
A diamond is the need to sink the copper process, that is, the hole in the copper plating, making it possible to connect the upper and lower layers, such as holes, the original hole, etc.
