PCB is an important electronic component, a support for electronic components, and a carrier for electrical connection of electronic components. Because it is made using electronic printing, it is called a "printed" circuit board.
There are three main division types of PCB circuit boards:
1. Single panel
Single-Sided Boards On the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side (when there are SMD components, it is the same side as the wires, and the plug-in devices are on the other side). Because the wires only appear on one side, this kind of PCB is called a single-sided (Single-sided). Because the single board has many strict restrictions on the design of the circuit (because there is only one side, the wiring cannot cross and must go around a separate path), so only early circuits used this type of board.
2. Double panel
Double-Sided Boards This type of circuit board has wiring on both sides, but to use the wires on both sides, there must be appropriate circuit connections between the two sides. Such "bridges" between circuits are called vias. Vias are small holes on a PCB, filled or painted with metal, that can be connected to wires on both sides. Because the area of the double-sided board is twice as large as that of the single-sided board, the double-sided board solves the difficulty of interleaving wiring in the single-sided board (it can be conducted to the other side through the hole), and it is more suitable for use in more complex circuits than the single-sided board.
3. Multilayer board
Multi-layer boards (MulTI-Layer Boards) In order to increase the area that can be wired, multi-layer boards use more single or double-sided wiring boards. A printed circuit board with a double-sided inner layer, two single-sided outer layers, or two double-sided inner layers and two single-sided outer layers, alternated together by a positioning system and insulating bonding materials, and conductive patterns. Printed circuit boards that are interconnected according to design requirements become four-layer and six-layer printed circuit boards, also known as multi-layer printed circuit boards. The number of layers of the board does not mean that there are several independent wiring layers. In special cases, an empty layer will be added to control the thickness of the board. Usually, the number of layers is even and includes the outermost two layers. Most motherboards are 4 to 8-layer structures, but technically, nearly 100-layer PCB boards can be achieved. Most large supercomputers use fairly multi-layer motherboards, but because such computers can be replaced by clusters of many ordinary computers, ultra-multi-layer boards have gradually fallen out of use. Because the layers in the PCB are tightly combined, it is generally not easy to see the actual number, but if you look closely at the motherboard, you can still see it.
The role of PCB
After the electronic equipment adopts the printed board, due to the consistency of the same type of printed board, the error of manual wiring is avoided, and the automatic insertion or mounting of electronic components, automatic soldering, and automatic detection can be realized, which ensures the quality of the electronic equipment. , improve labor productivity, reduce costs, and facilitate maintenance.
PCB advantages
The reason why PCB can be used more and more widely is because it has many unique advantages, which are summarized as follows.
high density. For decades, the high density of printed boards has been able to develop with the integration of integrated circuits and the advancement of mounting technology.
High reliability. Through a series of inspections, tests and aging tests, the PCB can be guaranteed to work reliably for a long time (usage period, generally 20 years).
Designability. For various performance requirements of PCB (electrical, physical, chemical, mechanical, etc.), printed board design can be realized through design standardization and standardization, with short time and high efficiency.
producibility. With modern management, standardization, scale (quantification), automation and other production can be carried out to ensure the consistency of product quality.
Testability. A relatively complete test method, test standard, various test equipment and instruments have been established to detect and identify the qualification and service life of PCB products.
Assemblability. PCB products are not only convenient for standardized assembly of various components, but also automated and large-scale mass production. At the same time, PCB and various component assembly parts can also be assembled to form larger parts, systems, and even complete machines.
maintainability. Since PCB products and various component assembly components are standardized in design and mass production, these components are also standardized. Therefore, once the system fails, it can be replaced quickly, conveniently and flexibly, and the service system can be quickly restored. Of course, more examples can be given. Such as the system miniaturization, light weight, high-speed signal transmission and so on.
The PCB industry is developing rapidly
Since the reform and opening up, China has attracted a large-scale transfer of manufacturing in Europe and the United States due to its preferential policies in labor resources, markets, and investment. development of related industries. According to China CPCA statistics, in 2006, the actual output of my country's PCB reached 130 million square meters, the output value reached 12.1 billion US dollars, accounting for 24.90% of the global total PCB output value, surpassing Japan to become the world's first. From 2000 to 2006, the average annual growth rate of China's PCB market reached 20%, far exceeding the global average. The global financial crisis in 2008 had a huge impact on the PCB industry, but it did not cause a catastrophic blow to China's PCB industry. Under the stimulus of the national economic policy, China's PCB industry experienced a comprehensive recovery in 2010. In 2010, China's PCB output value reached 19.971 billion US dollars. . Prismark predicts that China will maintain a compound annual growth rate of 8.10% from 2010 to 2015, higher than the global average growth rate of 5.40%.
Unbalanced regional distribution
China's PCB industry is mainly distributed in South China and East China, and the sum of the two accounts for 90% of the country's total. The effect of industrial agglomeration is obvious. This phenomenon is mainly related to the fact that the main production bases of China's electronics industry are concentrated in the Pearl River Delta and the Yangtze River Delta.
PCB downstream application distribution
The downstream application distribution of China's PCB industry is shown in the figure below. Consumer electronics accounted for the highest proportion, reaching 39%; followed by computers, accounting for 22%; communications accounted for 14%; industrial control/medical equipment accounted for 14%; automotive electronics accounted for 6%; defense and aerospace accounted for 5%.
backward technology
Although China is already the world's largest in terms of industrial scale, in terms of the overall technical level of the PCB industry, it still lags behind the world's advanced level. In terms of product structure, multi-layer boards account for most of the output value, but most of them are mid-to-low-end products with less than 8 layers. HDI, flexible boards, etc. have a certain scale, but in terms of technical content, they exist with foreign advanced products such as Japan. The gap, the IC substrate with the highest technical content is rarely produced by domestic companies.
What are the types of PCB board materials?
94V-0 and 94V-2 belong to a class of flame retardant grade materials, and 94V-0 is the highest flame retardant grade material of the two. The pcb sheet is generally divided into several colors, green is the most common, and black, red, blue, yellow color and quality are irrelevant, just a personalized performance.
The material and thickness of the PCB board are mainly considered, and the color is rarely considered. You should be talking about the color of the solder mask ink! Solder mask ink colors are white, yellow, black, red, blue, and a transparent ink, the most used is green ink. The solder mask ink used is different according to the accuracy requirements of the board.
In terms of materials, it can be divided into organic materials and inorganic materials
a. Organic material
Phenolic resin, glass fiber/epoxy resin, Polyimide, BT/Epoxy, etc. are all included.
b. Inorganic material
Aluminum, Copper-invar-copper, ceramic, etc. belong to it.
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