If you have the opportunity to pick up a printed circuit board (PCB), a little observation will find that there are many large and small holes on the circuit board, and you will also find many dense small holes through the light, the purpose of these holes is not for good-looking, each hole is designed for its purpose. Today, let's learn with the Shenzhen circuit board factory-SysPCB, why are there holes on the circuit board? What is PTH/NPTH/vias?
These holes on the PCB can be roughly divided into two types: PTH (Plating Through Hole) and NPTH (Non Plating Through Hole). The "through hole" here is because this kind of hole is really from one side of the circuit board through to the other side.
How do you distinguish between PTH and NPTH?
In fact, it is very simple. Refer to the picture in the front of the article. Just look at the hole wall for bright plating marks. The holes with plating marks are PTH, and the holes without plating marks are NPTH.
What is the use of PTH (plated through hole)?
Generally, there are two uses for the PTH holes in the circuit board. One is for soldering the feet of traditional DIP components. The diameter of these holes must be larger than the diameter of the soldering feet of the components, so that the components can be inserted into the holes for soldering.
Another relatively small PTH, usually called via, is used to connect and conduct the copper foil circuit between two or more layers of the circuit board(PCB), because the PCB is made of many copper foils. The layer stack is accumulated, and each layer of copper foil will be laid with another insulating layer, which means that the copper foil layers cannot communicate with each other, and the signal connection is by these PTH, so also call it as "Via".
What is the purpose of NPTH (non-plated through hole)?
If you pay a little attention, you will find that the aperture of NPTH is usually larger than that of PTH, because most of NPTH is used as a locking screw, and some are used to install some connectors.
In addition, some will also design NPTH on the edge of the board as the location of the test fixture. In the early days, it will also be used as a fixed circuit board for SMT. Most of SMT machines now use clamping to fix the circuit board. However, a board that is too thin may still need to be fixed with NPTH to avoid clamping deformation.
