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中文If you have the opportunity to pick up a piece of printed circuit board (PCB), a little observation, you will find that the circuit board with many large and small holes, hold it up to the ceiling lights to see, but also found that many densely packed holes through the light, these holes are not where to set up a good-looking, each hole can be the purpose of its design, and the more holes, basically means that the PCB is more expensive to manufacture. The more holes, it basically means that the PCB is more expensive to manufacture.
These holes on the PCB can be largely divided into PTH (Plating Through Hole) and NPTH (Non Plating Through Hole) two categories, here said ‘through hole’ because this hole is really from one side of the board through to the other side, in fact, in addition to through holes in the board, there are other holes that do not go through the board. In fact, in addition to through holes, there are other holes in the circuit board that are not through the board, interested friends can refer to this article: https://ucpcba.com/what-is-pcb-through-hole-blind-hole-buried-hole/
How to distinguish between PTH and NPTH?
In fact, it is very simple, refer to the following pictures, just look at the vertical hole wall there is no bright metal plating marks can be judged, there are plating marks of the hole is PTH, no plating marks of the hole is NPTH.
What does that NPTH (Non-Plated Through Hole) do?
If you pay a little attention, you will find that the aperture of the NPTH is usually larger than the PTH, because most of the NPTH is used as a screw locking payment, some are used to install some links outside the connector fixed, and some are card mechanism.
In addition, some PCB will also be in the board edge (break-away, coupon, folding edge) design NPTH for the positioning of the test fixtures, the early days will also be taken as SMT to beat / paste when fixed circuit boards used, and now most of the SMT patch hitting machine to use a clamping method without the use of a thimble to fix the circuit board. However, boards that are too thin may still need to be fixed with an NPTH to avoid deformation of the clamp.
What is the function of PTH (Plated Through Hole) and what is Via ?
Generally in the circuit board PTH holes will have two purposes, one is used to solder the traditional THD parts feet with these holes must be larger than the diameter of the parts of the soldering feet, so that the parts can be inserted into the holes to do the soldering.
Another smaller PTH, usually called via, they are used to connect and conduct the circuit board (PCB) between the different layers of copper foil wiring, because the PCB is basically a stack of many copper foil layers accumulated, neighbouring copper foil (copper) layer will be paved with a layer of insulation between the layers, that is to say, the copper foil material, each other can not be intercommunicated, and between different layers of copper foil signal transmission rely on via. The signal transmission between different copper foil layers relies on via.
