PCB was born in 1936, the technology will be widely used in military radio by the United States in 1943; Since the middle of the 1950s the PCB technology has been widely adopted. PCB applications have penetrated almost every terminal field of the electronics industry, including computers, communications, consumer electronics, industrial control, medical equipment, defense, aerospace, and many other fields.
PCB developing from single-layer to double-sided, multi-layer and flexible, and still maintain their respective development trends. As a result of continuous high-precision, high density and high reliability of the direction of development, and continue to reduce the size, reduce costs and improve performance, making the PCB still maintained a strong vitality in the future development of electronic equipment.
So how is the PCB designed? Read the following seven steps to understand:
Including preparing the library and schematics.Firstly preparing the schematic SCH component library and the PCB component package Before proceeding with the PCB design.
The PCB component package is preferably based on the standard size of the selected device by engineer. In principle, to establish the PC component package library, and then build the schematic SCH component library.
PCB components package library requirements are higher, it directly affects the PCB installation; Schematic SCH component library requirements are relatively loose, but pay attention to the definition of pin attributes and PCB components with the corresponding library package.
2, PCB structure design
According to the board size and the mechanical positioning which has been identified and to draw PCB frame in the PCB design environment, and according to the positioning requirements to put connectors, buttons / switches, screw holes, assembly holes and so on.
Fully consider and determine the wiring area and non-wiring area (such as the screw hole around the scope of non-wiring area).
3, PCB layout design
Layout design is that put the device in the PCB board box based on the design requirements of the device. Create a network table (Design → Create Netlist) in the schematic tool, and then import the network table (Design → Import Netlist) in the PCB software. After the success of the network table will exist in the software background, through the Placement operation can be all the devices out of the pin between the line suggested that the connection, then the device layout can be designed.
PCB layout design is the first important process in the PCB design process, the more complex the PCB board, the layout of the better and more directly affect the late implementation of the degree of difficulty.
The layout design relies on the circuit board designer’s foundation and rich experience in design, and the circuit board designers are at a higher level. The experience of the primary circuit board designer is still shallow, suitable for small module layout design or the whole board is difficult PCB layout design task.
4, PCB layout design
PCB layout design is the PCB design of the largest workload, directly affect the performance of the PCB board is good or bad.
In the PCB design process, the wiring generally has three realms:
The first is the cloth, which is the PCB design of the most basic entry requirements;
Followed by the performance of electrical performance, which is a measure of whether a standard PCB board, after the line cloth, carefully adjust the wiring, so that it can achieve the best electrical performance;
Again is neat and beautiful, disorganized wiring, even if the electrical performance clearance will be to the late plate optimization and testing and maintenance brought great inconvenience, wiring requirements uniform, can not be criss-cross no rules.
5, Wiring optimization and silk screen display
“PCB design is not the best, only better”, “PCB design is a defective art”, which is mainly because the PCB design to achieve all aspects of hardware design requirements, and individual needs may be between the conflict, fish and Bear’s paw can not have both.
For example: a PCB design project through the circuit board designer needs to be designed into a 6-layer board, but the product hardware for cost considerations, the requirements must be designed for the 4-layer board, then only sacrifice the signal shield formation, resulting in adjacent wiring The signal crosstalk between the layers increases and the signal quality decreases.
The general design experience is that optimizing the routing time is twice the time of the initial cabling. PCB layout optimization is completed, the need for post-processing, the primary treatment is PCB board silk screen logo, the design of the bottom of the silk screen characters need to do mirror processing, so as not to be confused with the top screen printing.
6, Network DRC inspection and structural inspection
Quality control is an important part of PCB design process, the general quality control means include: design self-test, design mutual inspection, expert review meeting, special inspection.
Schematic diagram and structural elements map is the most basic design requirements, network DRC inspection and structural inspection is to confirm the PCB design to meet the schematic netlist and structural elements of the two input conditions.
General circuit board designers will have their own accumulation of design quality check Checklist, (our company has many years of pcb production experience, we have a number of production lines, with experienced engineers and advanced production equipment, we provide hard board, soft board, pcb Assembly and many other pcb services).
Part of the entry comes from the company or department of the specification, the other part comes from their own experience. Special inspection includes the design of the Valor inspection and DFM inspection, these two parts concerned about the PCB design output back-end processing light painted files.
7, PCB board
Before the PCB is officially machined, the board designer needs to communicate with the PCB for the PE of the mill, and the manufacturer’s questions regarding the PCB processing are included. This includes but is not limited to: PCB board type selection, line layer width Line spacing adjustment, impedance control adjustment, PCB stacking thickness adjustment, surface treatment processing technology, aperture tolerance control and delivery standards.
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