The number of printed circuit board layers can be divided into several types

The number of layers of printed circuit boards is mainly single-layer, double-layer and multilayer circuit boards. At present, the most commonly used is double-layer circuit boards, and the number of layers of printed circuit boards is different. The manufacturing process, materials, precision, and The application area will be different, the following small series to outline the basic knowledge of several layers of circuit boards.

Print single-sided circuit board:

As we just mentioned, on the bottommost PCB, parts will gather on one side and wires will gather on the other side. Since the wires only appear on one side, we call this type of PCB a single-sided board. Because the single panel has a lot of serious binding on the planned circuit (since only one side, the wiring can not be crossed and it is necessary to go around a single path), only the previous circuit is used for this kind of board.

Printed double-sided circuit board:

Both sides of this board have wiring. However, to use double-sided wires, it is necessary to have proper circuit connections between the two sides. This "bridge" between circuits is called a via. The via hole is on the PCB, covered or coated with a metal hole, which can be connected to the double-sided wire. Because the double-sided board is twice as large as the single-sided board, and because the wires can be interwoven (wrap around to the other side), it is more suitable for use on circuits that are more cluttered than a single board.

Printed circuit board

Printed multilayer circuit board:

Multi-layer board: In the more cluttered application requirements, the circuit can be settled into multi-layered plans and pressed together, and a through-hole circuit is arranged between the layers to connect the layers of the circuit. The copper foil substrate of the inner layer is first cut into suitable specifications for processing and production. Before the film is pressed on the substrate, it is usually necessary to use brush grinding, micro-etching, etc., to properly treat the copper foil on the surface, and then attach the dry film photoresist with appropriate temperature and pressure. The substrate coated with the dry film photoresist is sent to an ultraviolet exposure machine. The photoresist reacts after the ultraviolet light shines on the transparent area of the film. The dry film in this area will be later developed and copper-etched. It is saved as an etching resist, and the image on the film is transferred to the photoresist on the surface of the board. After tearing off the maintenance film on the film surface, the unlighted area on the film surface is first developed with an aqueous sodium carbonate solution, and the exposed copper foil is etched away with a mixture solution of hydrochloric acid and hydrogen peroxide to form a circuit. At the end of the film, the water-repellent dry film resist was removed.

Print more than six layers of multilayer boards:

About six layers (including) or more of the inner layer of the circuit board to actively position the punching machine to punch out the inter-layer alignment of the riveted reference hole. Four-layer circuit boards Multi-layer boards use more single- or double-sided wiring boards in order to add areas that can be routed. The multilayer board uses several double-sided panels and is laminated (laminated) after placing an insulating layer between each layer. The number of layers on the board represents several layers of independent wiring layers. Usually, the number of layers is even, and includes the outermost two layers. Most motherboards are planned from 4 to 8 layers, but they can be nearly 100 layers in skill.

Large-scale supercomputers mostly use appropriate multi-layer motherboards. However, since these types of computers can now be replaced with clusters of many common computers, super multi-layer boards are gradually being used. Since the layers in the PCB are closely linked, the number of internships is usually not very simple, but if you look closely at the motherboard, you may be able to see it. The active detection skills of the circuit board are used along with the introduction of surface mount technology, and the board packaging density is rapidly added. Therefore, even for a circuit board with a low density and a normal number, the active detection of the circuit board is not only economical but also economical. In cluttered circuit board testing, two common methods are needle bed testing and dual probe or flying probe testing.

PCB board printing technology has also been more and more advanced, from the original single-sided and double-sided, to the subsequent multi-layer circuit board and super multi-layer circuit board, technology has been continuously researched and innovated, with more PCBs The progress in the technological advancement of various industries such as the electrical appliance industry and the electronics industry has progressed.