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The printed circuit board can be divided into rigid printing plate and flexible printing plate according to the product materials. The rigid printing plate has phenolic paper laminate, epoxy paper laminate, polyester glass felt laminate, epoxy glass cloth printed laminate. Flexible also known as flexible printed circuit board (FPC), Made of polyimide or polyester film with high reliability and high curvature.
This circuit board has good heat dissipation, can be bent, folded and rolled, and can be moved and scaled in FPC space. The 3d can be used to reduce volume and realize light quanta, miniaturization and thin-type, thus realizing the integration of devices Components and wires. FPC is widely used in computers, communications, aerospace and home electronics.
Features of flexible circuit board:
(1) FPC is small and light.
(2) FPC can move, bend and twist.
(3) FPC has excellent electrical performance, dielectric properties and heat resistance.
(4) FPC has high reliability assembly and assembly operation.
(5) FPC can be installed with three connections.
(6) FPC is conducive to heat diffusion.
(7) Low cost.
(8) Continuous processing.
The flexible circuit board is a printed circuit made of flexible base insulation material, which has the advantages of many rigid printed circuit boards. This product is small, lightweight, greatly reducing the volume of equipment, the application of electronic products with high density, miniaturization, and light, and thin - type, high - reliable development needs.
With high bending resistance, can bend freely, winding, twisting, folding, stereo wire, suitable for space layout for any arrangement, change shape, and any move and scale in three-dimensional space, to achieve component assembly and wire connection integration.
FPC comes with excellent electrical performance, high temperature and fire chemical resistance. Moreover, it provides stable change, good stability and high reliability.
With high assembly reliability, it is convenient for circuit design and can greatly reduce Consider the assembly workload, and it is easy to ensure the efficient operation of the circuit and reduce the cost of the whole machine.
High density: more than 100 years, high density printing plate has been developed with the improvement of integrated circuit integration and installation technology. High reliability: through a series of tests, tests and aging tests, PCB can be guaranteed to work reliably for a long time (usually 20 years).
Design: for different properties of PCB (electrical, physical, chemical, mechanical, etc.), the design of printed plate can be achieved by standardizing design, standardization, etc., which is Short and effective.
Productivity: adopt modern management, can bring standard, scale (quantity), automation and other production, and ensure stable product quality.
Testability: Test methods, test standards, various test equipment and tools have been established to detect and verify PCB product lifecycle expertise and service levels.
Electronics through the PCB, due to the consistency of the same PCB, to avoid artificial connection errors, and can realize automatic instrumentation or SMT electronic components, automatic soldering, Automatic detection, ensure the quality of the electronic equipment, improve labor productivity, reduce costs, and easy maintenance.
There are similarities and differences between circuit hardwood and flexible circuit boards. For flexible circuit board, rigid circuit board applies to the board widely than, because the previous rigid circuit board, so most of the rigid circuit board design elements have been used in the design of the flexible circuit board.
Compared with rigid circuit board, flexible circuit board has relatively little heat dissipation efficiency, so it must provide enough wire width. Considering heat dissipation of flexible circuit board, it is needed to give the conductors extra width or spacing.
in general case, rectangle can be chosen, which can be very good in saving facilities, and should have enough free margin near edge. Therefore, the width and spacing of the smaller wires should be minimized and smooth transitions should be as smooth as possible. The sharp corners cause strain to focus naturally, causing failure.
PCB is one of the most basic concepts that a beginner to electrical needs to grasp. Maybe, you've heard about PCB labels everywhere, it's so familiar that you forget the main concept of this word. If you are a beginner in the field of electronics or are learning the concepts and terms related to PCB. Please refer to the following writing information
The PCB will have many layers, it not capable of conducting electricity, but must rely on paths and pad points on the surface. These paths will play the role of connecting and transmitting electrical signals between points located at different locations on the PCB.
Thus, relying on PCB paths will allow the transmission of signals and power between their surfaces mounted physical devices (such as ICs, resistors, inductors, etc.). In order to transmit a signal on a PCB, you must perform a soldering process to create an electrical connection between the PCB and the electronic components.
In addition to conducting electricity, solder also acts as an adhesive to prevent components from falling off the circuit
PCB printed circuit board is the name commonly used these days, before that it was also known by two other names as “Printed Wiring Boards” and “Printed Wiring Cards”.
Before the advent of PCBs, the old circuits were built using point-to-point wiring, which was laborious, confusing, and especially difficult to handle if something went wrong. This old type of circuit frequently fails at the connections and short circuit when the insulation of the wire is aging or cracked.
Another significant advance after this stage was the development of the winding, where a small gauge wire was wound around the post at each connection point to create an airtight, high-strength, and replaceable connection that's easier.
As electronics moved from vacuum tubes and relays to silicon and integrated circuits, the size and cost of electronic components began to decrease. At this time, electronics became more popular, marking the beginning of a period of strong development of electronic products to this day.
You can see PCB circuits almost everywhere such as phones, televisions, computers, washing machines, refrigerators… almost every electronic device in the home
As mentioned in the concept section, a PCB is a printed circuit made up of many layers of different materials interspersed with each other. Each layer will take on a separate role, connected by heat or adhesive to form a single block.
This is the most basic layer of material that can be considered the substrate for a PCB, usually fiberglass. Historically, the most common material for this substrate has been fiberglass “FR4”. FR4 will help PCB with good rigidity and thickness, hard to break, crack. In addition, there are flexible PCBs that are designed based on a high-temperature thermoplastic substrate (maybe Kapton or equivalent).
PCB will have different thickness according to the number of layers of printed circuit; some common thickness is 1.6mm (0.063") or 0.8mm thickness for adruino circuits.
Cheap PCBs and boards are usually made of other materials like epoxides or phenolics. They will not be as durable as FR4 but the cost will be greatly reduced if made of these materials. You can recognize these cheap PCBs when you directly solder them, often with a very unpleasant odor.
These types of cheap substrates are often found in low-cost consumer electronics from China which is why some home electronics from China are so cheap. Phenolic substrates have a low thermal decomposition temperature that causes them to delaminate, smoke and blacken when the soldering iron is kept too long on the printed circuit board.
The next layer of the printed circuit board is a thin copper foil, which is laminated with heat and an adhesive. On conventional 2-sided PCBs, copper is coated on both sides of the substrate. In lower cost electronics, the PCB may have only copper on one side.
When someone refers to a double-sided or 2-layer board, they are usually referring to the number of co-factors that make up a PCB (2).
This calculation means that a PCB circuit can have at least 1 copper layer (for 1-layer circuits) or 16 copper layers (for 16-layer circuits) or more.
The thickness of copper can vary and is specified by weight, usually in some countries the amount of copper to be coated will be measured in ounces per square foot. Most PCBs will be coated with 1oz of copper per square foot but some very high power handling PCBs may use 2 or 3oz of copper.
According to this formula, each oz per square foot corresponding PCB will have a thickness of about 35 micrometers
The top layer of copper foil is called the solder mask layer. This is the layer that plays the role of creating a typical color for printed circuits, usually green (sometimes there will be other colors such as blue, red, purple, and white depending on the manufacturer).
It is coated with copper with the task of isolating electrical lines from random contact or sticking to the outside metals, solder or other conductive bits. In addition, this mask layer also helps the user to weld in the correct positions and avoid jumping welds.
The solder mask will cover most of the surface, but will expose the silver rings and the SMD pad so users can solder components to these locations.