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Home > Mall Dynamic > What IS A Printed Circuit Board? What IS A Printed Circuit Board
PCB is short for Printed Circuit Board (Printed Circuit Board). Also known as printed circuit board, printed circuit board, because it is produced by electronic printing, it is called "printed" circuit board. A printed circuit board is a substrate for assembling electronic parts, and is a printed board that forms point-to-point connections and printed components according to a predetermined design on a common substrate. The main function of the product is to make a variety of electronic components form a predetermined circuit connection, play the role of relay transmission, is the key electronic interconnection of electronic products, known as the "mother of electronic products". As a substrate and key interconnect for electronic parts loading, PCBS are required for any electronic device or product. This article will explain the PCB application field, development process and manufacturing principle in detail
When we open the keyboard of a general-purpose computer, we see a soft film (flexible insulating substrate) printed with a silver-white (silver paste) conductive pattern and a health pattern. Because of the general screen printing method to obtain this pattern, we call this printed circuit board for silver paste printed circuit board. And we go to the computer city to see a variety of computer host board, graphics cards, network cards, modems, sound cards and household appliances on the printed circuit board is different. The substrate used is made of paper base (usually used for single side) or glass cloth base (often used for double side and multi-layer), pre-pregassed phenolic or epoxy resin, one or both surface layers are glued to a copper-coated sheet and then laminate and cure. This circuit board covered with copper sheet plate, we call it a rigid plate. Then made into a printed circuit board, we call it a rigid printed circuit board. Single-sided printed circuit graphics we call single-sided printed circuit board double-sided printed circuit graphics, and then through the metallization of the hole to form a double-sided printed circuit board, we call it a double panel. If the printed circuit board with a double-sided inner layer, two single-sided outer layer or two double-sided inner layer and two single-sided outer layer is used, the printed circuit board that is interconnected according to the design requirements through the positioning system and the insulating binder material is alternately connected according to the design requirements of the conductive graphics becomes a four-layer, six-layer printed circuit board, also known as a multi-layer printed circuit board. There are now more than 100 layers of functional printed circuit boards
PCB production process is more complex, it involves a wide range of processes, from simple machining to complex machining, there are ordinary chemical reactions and photochemical electrochemical thermochemistry and other processes, computer-aided design CAM and other aspects of knowledge. Moreover, in the production process, there are many process problems and new problems will be encountered from time to time, and some problems will disappear without finding out the cause. Because the production process is a non-continuous form of assembly line, any problem in any link will cause the whole line to stop production or a large number of scrapped consequences. If the printed circuit board is scrapped, it can not be recycled. The job of process engineer is stressful, so many engineers leave the industry to work in sales and technical services for PCB equipment or materials manufacturers.
The substrate of the board itself is made of an insulating, non-bendable material. The small wire material that can be seen on the surface is copper foil. Originally, the copper foil is covered on the whole board, and the middle part is etched away during the manufacturing process, and the remaining part becomes a network of small lines. These lines are called conductors (conductorpattern) or wiring, and are used to provide circuit connections for parts on the PCB
To secure the parts to the PCB, we solder their pins directly onto the wiring. In the most basic PCB(single panel) parts are concentrated on one side, the wire is concentrated on the other side, so we need to make a hole in the board, so that the connector can pass through the board to the other side, so the connector of the part is welded on the other side. Because of this, the front and back sides of the PCB are called the ComponentSide and Solder Side, respectively.
If there are some parts on the PCB that need to be removed or put back after production, then the Socket will be used when the part is installed. Since the socket is welded directly on the board, the parts can be arbitrarily disassembled.
If you want to connect two PCBS to each other, we generally use the edgeconnector, commonly known as "gold finger". The gold finger contains many exposed copper pads, which are in fact part of the PCB wiring, usually when connected, we insert the gold finger on one PCB into the appropriate Slot on the other PCB (generally called expansion Slot). In computers, such as video cards, sound cards and other similar interface cards, are connected to the main board by the goldfinger.
The green or brown on the PCB is the color of soldermask, which is an insulating protective layer, which can protect the copper wire and prevent the parts from being welded to the incorrect place, and another layer of silkscreen will be printed on the soldermask. Usually on this will be printed with text and symbols (mostly white) to mark the position of each part on the board, screen printing surface is also called the icon surface (legend).
Printed circuit board The complex circuit copper wire between parts and parts, after careful and neat planning, etched on a board to provide electronic components in the installation and interconnection of the main support body, is an indispensable basic part of all electronic products.
Printed circuit board A flat plate made of a non-conductive material, usually with a design pre-drilled for mounting chips and other electronic components. The holes of the components help to connect the pre-defined metal paths printed on the surface of the board electronically. After the pins of the electronic components are passed through the PCB, a conductive metal electrode is attached to the PCB to form a circuit.
A brief history of development: China began the development of single-sided printed boards from the mid-1950s, first applied to semiconductor radios. In the 1960s, the self-reliant development of China's foil coated plate substrate, so that copper foil etching method has become the leading process of PCB production in China, and in the 1960s, it has been able to produce single panels in large quantities. Small batch production of double-sided metallized hole printing, and in a few units began to develop multi-layer plates. In the 1970s, the graphic electroplating etching process was promoted in China, but due to various disturbances, special materials and special equipment for printed circuits did not keep up in time, and the entire production technology level lagged behind the advanced level of foreign countries. In the 1980s, due to the batch of reform and opening up policy, not only introduced a large number of single-sided, double-sided and multi-layer printed board production lines with the advanced level of foreign countries in the 1980s, but also improved China's printed circuit production technology level rapidly after more than 10 years of digestion and absorption.
Development direction: In recent years, China's electronics industry has become one of the main pillars of domestic economic growth, with the rapid development of computers, communication equipment, consumer electronics and automotive industries, PCB industry has also achieved rapid development. With the development of printed circuit products, new materials, new process technology and new equipment are required. China's printed electrical materials industry in expanding output at the same time, more attention should be paid to improving performance and quality; The printed circuit special equipment industry is no longer a low-level imitation, but the development of production automation, precision, multi-function and modern equipment. PCB production set the world's high-tech in one, printed circuit production technology will use liquid photographic imaging, direct plating, pulse plating, laminated multilayer board and other new processes.
PCB features high density, high reliability, designability, producibility, assembly and maintainability of six aspects.
- Generally speaking, the more complex the function of the electronic product, the longer the loop distance, the more the number of contact pins, the more the number of layers required by the PCB, such as high-end consumer electronics, information and communication products; The soft board is mainly used in products that need to be bent: such as notebook computers, cameras, automotive instruments, etc. PCB classification according to the number of layers, can be divided into single panel (SSB), double panel (DSB) and multi-layer board (MLB); According to the softness, it can be divided into rigid printed circuit board (RPC) and flexible printed circuit board (FPC). In industrial research, in general, according to the basic classification of PCB products, the PCB industry is subdivided into six major sub-industries, such as single panel, double panel, conventional multi-layer board, flexible board, HDI(high-density sintering) board, and packaging substrate.
The PCB upstream industry includes PCB substrate board raw material suppliers and PCB production equipment suppliers, and the downstream industry includes consumer electronics, computers and peripheral products, automotive and mobile phone industries. According to the industry chain, it can be divided into raw materials - copper clad plate - printed circuit board - electronic product applications. The specific analysis is as follows:
Glass fiber cloth: Glass fiber cloth is one of the raw materials of copper clad plate, made of glass fiber yarn, accounting for about 40% of the cost of copper plate (thick plate) and 25%(sheet). Glass fiber yarn is calcined into liquid state by silica sand and other raw materials in kiln, pulled into very fine glass fiber through a very fine alloy nozzle, and then twisted hundreds of glass fiber into glass fiber yarn.
Copper foil: Copper foil is the largest proportion of copper clad plate cost raw materials, accounting for about 30% of the cost of copper clad plate (thick plate) and 50%(sheet), so the price increase of copper foil is the main driving force for the price increase of copper clad plate.
Copper clad plate: Copper clad plate is a product of glass fiber cloth and copper foil pressed together by epoxy resin and other fusion agents, and is the direct raw material of PCB. It is made into printed circuit board after etching, electroplating and multi-layer plate pressing.
FR-4, as the most common substrate/substrate material for pcb, is usually present in many electronic devices, and is also the most common intelligent manufacturing. FR-4 (PCB) is made of fiberglass and epoxy resin combined with a laminated copper cladding.
Some of its main applications: computer graphics cards, motherboards, microprocessor boards, FPgas, CPLDS, hard drives, RF LNA, satellite communication antenna feeds, switching mode power supplies, Android phones, and more.
With the rapid development of the printed circuit board industry, it has a significant role in medical equipment, industrial equipment, lighting and automotive and aerospace industries, the specific pcb board used in what aspects, the following small series one by one analysis.
One: the application of pcb in medical equipment
Today, the rapid progress of medical science is closely related to the rapid development of the electronics industry. Many microbiological equipment and other equipment are a separate base pcb, such as: pH meter, heartbeat sensor, temperature measurement, electrocardiogram machine,
electroencephalogram machine, nuclear magnetic resonance imaging machine, X-ray, CT scan, blood pressure machine, blood sugar level measurement equipment, incubators and other medical equipment.
Two: The application of pcb in industrial equipment
PCBS are widely used in the manufacturing industry, especially those with high-power mechanical equipment, which operates on high power and requires high current circuit drive. As a result, a thick layer of copper is pressed on top of the PCB, which is different from complex electronic PCBS,
and these high-power PCBS have currents up to 100 amps. This is particularly important in arc welding, large servo motor drives, lead-acid battery chargers, military industry, clothing cotton machines and other applications.
Three: the application of pcb in lighting
We see LED lights and high-intensity leds all around, these small leds that provide high-brightness light and are mounted on PCBS based on aluminum substrates. Aluminum has the property of absorbing heat and dissipating in air.
Therefore, due to the high power, these aluminum circuit boards are usually used in LED lamp circuits medium and high power LED circuits.
Four: pcb applications in the automotive and aerospace industries
The reverberation produced by our most common airplane and car motion uses a PCB called Flex PCB to meet these high force vibrations and make the PCB flexible. Flexible PCBS are lightweight, but can withstand high vibration, and because of their light weight, they can reduce the total weight of the spacecraft.
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