1, buried hole
The hole is a plated through hole which is connected with the two layer or more layers of a multi base plate, and the buried hole is in the inner structure of the circuit board.
Compared with the traditional plated through hole structure, the buried hole saves a lot of space. When the signal line density is very large, the need for more holes to connect the signal layer, but also need more signal to walk the line, can use the buried technology. However, because of the need for more program steps, the advantage of the line density is to increase the cost of the circuit board.
The blind hole is connected to the surface of the substrate will be plated through holes one or more layers, they are not all through the plate thickness. In the double sided multi substrate can be used on the blind hole, hole components can be connected through hole and blind hole through the circuit board. Blind hole can be on the plate layer are stacked on top of each other, and can be made smaller, so that it can provide more space and layout more signal line.