This chapter introduces the basic knowledge of circuit board design, including the basic knowledge of circuit board, the basic concepts of circuit board design and circuits.

The development process of PCB, the introduction of Altium Designer, the design process and manufacturing process of PCB, and the international

Introduction of famous semiconductor companies in the world.

Function and function of circuit board

Circuit boards are often used in electronic information systems. The following is a brief introduction to electronic information systems. Electronic information system

The typical structure is shown in Figure 1-1.

Electronic information system is usually referred to as electronic system for short, and the working flow of electronic system is as follows.

(1) Analog signals are generated by sensors.

(2) After signal processing (such as signal amplification, filtering, etc.), it is sent to an AD converter to be converted into a digital signal.

(3) The digital signal is sent to the central processing unit (CPU) for processing, and the parameters of the electronic system are adjusted by using the keys.

(4) Control the relBasic concepts of circuit board designay or motor to work according to the processed result, and use the display device (such as digital) for the processed result.

Tube, liquid crystal display, etc.), and at the same time send the processed results to a memory chip or a U disk or hard disk for storage.

Many CPUs have integrated AD converter modules, so there is no need to use AD converter alone. There are many kinds of sensors.

Various, such as temperature sensor, humidity sensor, current sensor, voltage sensor, photoelectric sensor, photoelectric encoder,

Camera, magnetic field sensor, grating ruler sensor and grating ruler sensor, etc. Signal processing includes signal filtering, amplification and limiting.

Amplitude, etc. The signal generated by the sensor is generally small, while the input signal of the AD chip is required to be within a certain amplitude range, such as

0~5V or 0~3V, etc., so it is necessary to amplify the signal to realize the conversion from analog signal to digital signal. CPU

Essentially, it is a complex digital circuit, which has many kinds, such as single chip microcomputer, DSP and ARM. Types of display devices

There are many kinds, such as digital tube, Light Emitting Diode (LED), liquid crystal display and touch screen. show

The function of the display device is to display the numerical value of parameters, such as using a digital tube to display the numerical value of temperature and using a light-emitting diode to indicate electrons.

The running status of the system (green light means that the electronic system is running normally, red light means that the electronic system has an alarm, etc.), and LCD display is used.

The change curve of display parameters, etc. The function of keys is to adjust the values of electronic system parameters. In practical engineering, the electronic department

The number of keys used in the system depends on the actual demand and is not fixed. Some electronic systems are relatively simple and do not need to be pressed.

Keys, while some electronic systems only need a few keys. There are many kinds of control mechanisms, such as relays, stepping motors, DC motors,

Switches and solenoid valves, etc.

Electronic information systems are widely used in household products, industrial production, space exploration and military defense.

Use various types of electronic information systems, such as intelligent washing machines at home, Yutu lunar rover and Zhu Rong Mars rover. current

In the popular electric vehicle, it can also be considered as a very complicated electronic information system. In the research and development process of electronic information system

First, we need to use circuit board design software (such as Altium Designer) to design the connection relationship between the pins of electronic components.

Draw a circuit board diagram; Then, give the circuit board diagram to the circuit board manufacturer, and the circuit board manufacturer will produce electricity according to the circuit board diagram.

Road board; Finally, the electronic components are soldered on the circuit board, and the program is burned into the CPU, and the whole electronic information is completed.

The design process of the system.

Function of circuit board
In the electronic information system, the circuit board has the following three functions.

(1) The circuit board is the carrier of all electronic components and plays the role of fixing electronic components, as shown in Figure 1-2. Among them,

Figure 1-2(a) shows the circuit board without soldering electronic components, and you can see that there are white characters and squares or rectangles on the circuit board.

White square. White characters represent symbols of electronic components, while white squares represent pads. When welding electronic components,

Firstly, the pins of the electronic components are placed on the pads of the circuit board, and then the pins of the electronic components are fixed by using an electric soldering iron and solder.

And the bonding pad are soldered together. Figure 1-2(b) shows the circuit board with electronic components soldered.

(2) the circuit board is used to realize the connection between the pins of electronic components, that is, all electronic components are connected by copper foil wires.

The pins of are reasonably connected together, as shown in Figures 1-3 and 1-4. Figure 1-3 shows the pictures drawn by Altium Designer software.

Circuit board diagram. Figures 1-4 show the manufactured circuit board. In the diagram, you can see many wires, which are made of copper.

Made to connect the pins of electronic components, called copper foil conductors. Before the technology of circuit board appeared in the early days,

The pins of electronic components are connected by metal wires, as shown in Figure 1-5. Using this connection form of metal wires, it is obvious that

There are two defects: first, metal wires are easy to break and the maintenance cost is relatively high; Secondly, if the pins of components are very close.

Assemblies, such as the components in Figure 1-4, cannot be welded with metal wires.

(3) The circuit board provides identification characters and graphics for the insertion, welding, inspection and maintenance of electronic components, as shown in Figure 1-3.

As shown. The yellow objects in Figure 1-3 include the labels of components (U1, R1, C1, etc.), the outline borders of components, etc. circuit board

The yellow object in the picture will be printed on the circuit board and appear white on the circuit board.

Basic concepts of circuit board design
EDA (Electronic Design Automation)

EDA is an acronym for Electronic Design Automation, which means electricity.

Sub-design automation. EDA can be simply understood as the technology of using computers to design circuits. Since the 1990s.

Since the early generation, EDA has developed from Computer Aided Design (CAD), computer aided manufacturing.

(CAM), Computer Aided Testing (CAT) and

Computer Aided Engineering (CAE) and other concepts developed. EDA technology refers to computer

Electronic CAD is developed for working platform, integrating the latest achievements of applied electronic technology, computer technology and intelligent technology.

General software package, assisting in electronic circuit simulation, programmable logic device design, circuit board design and integrated circuit design.

Waiting for work.

Early EDA technology was specially used for PLD(Programmable Logic Device),

CPLD(Complex PLD) and FPGA (Field Programmable Gate Array)

Program gate array) and ASIC (application specific integrated circuit),

Only professionals will touch it. Later, with the progress of computer technology and electronic technology, EDA technology gradually penetrated into electronics.

Various fields of design are also widely used in circuit board design, circuit simulation and other fields.

EDA software can be divided into five categories: circuit simulation software, circuit board design software, CPLD and FPGA design software, and single

The simulation software of the computer program and the design software of the integrated circuit.

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