PCB Technical - What are the functions of the various strip holes on the circuit board?

To be precise, this cannot be called a hole. The technical term is called a hole. The holes on the circuit board(PCB) are divided into three types: via holes (VIA), plug-in holes, and mounting holes. Via holes play the role of conduction and heat dissipation; plug-in holes are used for welding components, and the corners of the components are inserted and fixed with tin; mounting holes are used for screwing, and can be assembled with other components.
Generally speaking, via holes and plug-in holes are metallized holes (PTH), that is, the hole walls are metal attached and can be conductive, while the mounting holes are generally non-metallized holes (NPTH), and the hole wall is the substrate.

This hole is drilled by a CNC drill or laser, and then undergoes chemical copper plating, copper electroplating, and surface treatment (commonly sprayed tin and gold, and others have anti-oxidation, tin sink, etc.).
Generally, the circuit boards we see come in various colors, which are called solder mask inks, which can prevent short circuits and protect the board, which plays a beautiful role. Characters will be printed on the solder mask to facilitate identification of components during soldering repairs. The inks are green, red, blue, black, white, etc.
There are many holes on the surface of the circuit board, as shown in the figure below, which are usually divided into the following types:
1 represents the mounting hole of the separated original
It is to install in-line (separate) components on the circuit board through a certain process requirement.
2 represents the heat dissipation hole
This is a type of hole for heat dissipation, on the other side is a CPU chip.
3 represents via
This via is for connecting the wires on the front and back of the circuit board.
4 stands for mounting hole
The mounting hole, as the name suggests, is used to install a fixed circuit board.
5 Holes required by other technical specifications
For example, power circuit boards, such as transformers, have some cut holes or slots to ensure technical performance requirements.
What are the functions of the various strip holes on the circuit board?
To be precise, it is called a via. If it goes from the top layer to the bottom layer, it is called a through hole. If it is in the middle layer or half of it is called a blind hole. If there is no attribute, which means that the hole is not connected to the circuit, it is generally a mounting hole or used to match the structure. This kind of hole is generally larger. If it is connected to the circuit, it is generally used to connect two layers of circuits and can be used as Wires, if many holes are arranged in an array, are generally used to dissipate heat or to adapt to large currents.