Here are all the circuit boards you need to know

There are three types of circuit board systems

Circuit board single panel

Single-Sided Boards

We just mentioned that, so we call this kind of PCB single sided. Because there are many strict restrictions on the design circuit of a single panel (because there are only one side, the wiring can not cross each other, but must go around its own path), only the early circuits used this kind of board.

Double sided board

Double-Sided Boards

This circuit board has wiring on both sides. However, to use two sides of the wire, it is necessary to have a proper circuit connection between the two sides. The bridge between these circuits is called via. A pilot hole is a small hole in a PCB filled with or coated with metal, which can be connected with wires on both sides. Because the area of the double-sided board is twice as large as that of the single panel, and because the wiring can be staggered with each other (can be wound to the other side), it is more suitable for more complex circuits than the single panel.

Multilayer board

[multilayer board] in the complex application requirements, the circuit can be arranged into multi-layer structure and pressed together, and the through hole circuit is arranged between layers to connect the circuits of each layer.

Inner line

The copper foil substrate is cut into the size suitable for processing and production. Before the substrate is pressed, the copper foil on the surface of the board should be roughened by brush grinding and micro etching, and then the dry film photoresist should be tightly attached to it at the proper temperature and pressure. The substrate with the dry film photoresist is sent to the UV exposure machine for exposure. The photoresist will produce polymerization reaction after the light transmission area of the negative film is exposed by ultraviolet rays (the dry film in the area will be retained as etchant in the later development and copper etching steps), and the line image on the negative will be transferred to the dry film photoresist on the plate surface. After tearing off the protective film on the membrane surface, the non illuminated area on the film surface is removed by sodium carbonate water solution, and then the exposed copper foil is corroded and removed with hydrochloric acid and hydrogen peroxide solution to form a circuit. Finally, the dry film was washed out with sodium hydroxide solution. For the inner circuit board with more than six layers (including), the riveting reference hole of the alignment of the line between layers is punched out by the punching machine automatically.

Four layer circuit board

Multi-Layer Boards

In order to increase the area that can be wired, the multilayer board uses more single or double-sided wiring boards. The multilayer board uses several double-sided boards, and then puts a layer of insulation layer between each layer of board and then adheres (press).

The number of layers of the board represents several independent layers of wiring, usually even, and contains the outermost two layers. Most of the main board is 4-8 layers, but it can be nearly 100 layers of PCB. Most large supercomputers use quite many layers of host board, but because such computers can be replaced by many ordinary computer clusters, the super multi-layer board has gradually been used. Because the layers in PCB are closely combined, it is not easy to see the actual number, but if you carefully observe the host board, you may see it.

The automatic detection technology of circuit board is applied with the introduction of surface mounting technology, and makes the packaging density of circuit board increase rapidly. Therefore, even for the low density and general number of circuit boards, the automatic detection of circuit boards is not only basic, but also economic. In the complex circuit board detection, two common methods are needle bed test and double probe or flying needle test.