The Printed circuit board (PCB) appears in almost every electronic device. If there are electronic parts in a device, they are mounted on PCBS of various sizes. In addition to securing various small parts, the main function of a PCB is to provide electrical connections between the parts on the top. As electronic devices become more complex and require more and more parts, the wiring and parts on a PCB become more and more dense.
A standard PCB has no parts attached to it, and is often referred to as the "Printed circuit Wiring Board (PWB)".
The substrate of the board itself is made of insulating, heat-resistant materials that are not easily bent. The thin wire material THAT CAN be seen on the surface is copper foil. Originally, the copper foil is covered on the whole board, but in the manufacturing process, part of the copper foil is etched away, and the remaining part becomes a network of thin wires. These lines are called conductor patterns, or wiring, and are used to provide circuit connections to components on a PCB.
To attach the parts to the PCB, we solder their pins directly to the wiring. On the most basic PCB (single panel), the parts are all concentrated on one side and the wires are all concentrated on the other. So we need to make holes in the board so that the pins can go through the board to the other side, so the pins of the parts are welded to the other side. Because of this, the Solder Side and the Solder Side of the PCB are called the Component Side and Solder Side respectively.
If the PCB has parts on it that can be removed or put back on after it has been made, sockets will be used to install the parts. Since the socket is directly welded to the board, the parts can be disassembled and assembled arbitrarily.
To connect two PCBS to each other, we usually use a "goldfinger" edge connector. The Goldfinger contains many bare copper pads that are actually part of the PCB wiring. Usually, we insert the goldfinger on one PCB into a suitable Slot on the other PCB (commonly called an expansion Slot). In a computer, a display card, sound card, or SIMILAR interface card is connected to the main board by a GOLDfinger.
The green or brown on PCB is the color of solder mask. This is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. A silk screen is printed on top of the solder resistance layer. It is usually printed with words and symbols (mostly white) to indicate the position of the parts on the board. The screen printing surface is also known as the icon surface (legend).
The printed circuit board etches the complex copper circuit wires between the parts and the parts on a board after careful and tidy planning, providing the main support body for the installation and interconnection of electronic components, and is an indispensable basic part for all electronic products.
Printed circuit board A plate made of nonconductive material, usually with pre-drilled holes designed to house chips and other electronic components. The holes in the components help to electronically connect predefined printed metal paths on the board, pass the pins of the electronic components through the PCB, and then attach the conductive metal electrodes to the PCB to form a circuit.
According to its application field PCB can be divided into single panel, double panel, more than four layers of multi-layer board and soft board. Generally speaking, the more complex the function of electronic products, the longer the loop distance, the more the number of contacts, the more PCB layers are required, such as high-order consumer electronics, information and communication products, etc. The soft board is mainly used in products that need bending: such as notebook computers, cameras, automobile instruments, etc.
Manufacturing of printed circuit boards
Printed circuit boards are structural components formed by insulating materials supplemented with conductor wiring. Integrated CIRCUITS, TRANSISTORS, DIODES, passive components (such as resistors, capacITORS, connectors, etc.) and a wide VARIETY of other ELECTRONIC components are installed in the final product. Electrical signals and functions can be formed through wire connection. Thus, a printed circuit board is a platform that provides component connections to carry the foundation of the connected parts.
Because printed circuit board is not a general end product, so in the name of the definition of a slightly confused, for example: personal computer motherboard, called the host board and not directly called the circuit board, although there is a circuit board in the host board but not the same, so the assessment of the industry when the two related but can not say the same. Another example: because there are integrated circuit parts loaded on the circuit board, so the news media called it IC board, but in essence it is not equivalent to printed circuit board.
As electronic products tend to be multifunctional and complex, the contact distance of integrated circuit components is reduced, and the speed of signal transmission is relatively increased, followed by the increase of the number of connections and the local shortening of the length of distribution lines between points. These require the application of high-density line configuration and micropore technology to achieve the goal. Wiring and bonding are basically difficult to achieve for single and double panels, so the Circuit Board will move to MulTIlayer. In addition, due to the continuous increase of signal lines, more power layers and grounding layers are necessary means for design, which makes the MulTIlayer Printed Circuit Board more common.
For THE ELECTRICAL REQUIREMENTS OF HIGH SPEED SIGNALS, THE CIRCUIT BOARD MUST PROVIDE IMPEDANCE CONTROL WITH ALTERNATING current characteristics, high frequency TRANSMISSION capability, AND reduction of UNNECESSARY RADIATION (EMI). With Stripline and Microstrip structure, multilevel design becomes necessary. To REDUCE QUALITY PROBLEMS IN SIGNAL TRANSMISSION, insulation materials WITH low dielectric coefficient and low attenuation rate are used. In order to match the miniaturization and array of electronic components, the density of circuit boards is constantly increased to meet the demand. BGA (Ball Grid Array), CSP (Chip Scale Package), DCA (Direct Chip Attachment) and other groups of parts assembly, more promote the printed circuit board to an unprecedented high density realm.
Where the diameter of the hole less than 150um is known as Microvia in the industry, the use of this microhole geometry technology to make the circuit can improve the efficiency of assembly, space utilization and so on, at the same time for the miniaturization of electronic products also has its necessity.
For this type of structure of the circuit board product, the industry has a number of different names to call such a circuit board. For example, European and American companies used to call such products SBU (Sequence Build Up Process), which is generally translated as "sequential layer adding method", because the programs they made were constructed in a sequential way. As for the Japanese manufacturers, because the hole structure of these products is much smaller than the previous ones, the production technology of these products is called MVP (Micro Via Process), which is generally translated as "Micro hole Process". Some people because the traditional MulTIlayer Board is called MLB (MulTIlayer Board), so this kind of circuit Board is called BUM (Build Up MulTIlayer Board), generally translated as "layered MulTIlayer Board".