It can be observed that there are many large and small holes in the circuit board, and it can be found that there are many dense holes, and each hole is designed for its purpose. These holes can basically be divided into PTH (Plating Through Hole) and NPTH (Non Plating Through Hole) plating through hole, and we say “through hole” because it literally goes from one side of the board to the other, In fact, in addition to the through hole in the circuit board, there are other holes that are not through the circuit board.

PCB terms: through hole, blind hole, buried hole.

1. How to distinguish PTH and NPTH in through holes?

It can be judged if there are bright electroplating marks on the hole wall. The hole with electroplating marks is PTH, and the hole without electroplating marks is NPTH. As shown in the picture below:

2. The Usage of NPTH

It is found that the aperture of NPTH is usually larger than PTH, because NPTH is mostly used as a lock screw, and some is used to install some connections outside the connector fixed. In addition, some will be used as a test fixture on the side of the plate.

3. The Usage of PTH, What is Via?

Generally, PTH holes on the circuit board are used in two ways. One is used for welding the feet of traditional DIP parts. The aperture of these holes must be larger than the diameter of the welding feet of the parts, so that the parts can be inserted into the holes.

Another relatively small PTH, usually called via (conduction hole), is used to connect and conduction circuit board (PCB) between two or more layers of copper foil line, because PCB is composed of a lot of copper layers piled up, each layer of copper (copper) will be paved with a layer of insulation layer, that is to say, copper layer can not communicate with each other, The connection to its signal is via, which is why it is called “pass through hole” in Chinese. Via because the holes are completely invisible from the outside. Because the purpose of via is to conduct copper foil of different layers, it requires electroplating to conduct, so via is also a kind of PTH.