PCB circuit board is mainly layout design; the main advantage of using circuit board is greatly reduce the wiring and assembly errors, improve the level of automation and production labor. PCB circuit board design can be standardized, to swap; high wiring density, small volume, light weight, beneficial to the miniaturization of electronic equipment; conducive to the mechanization and automation of production, improve labor productivity and reduce the cost of electronic equipment.
Requirements of PCB circuit board design:
1, in the PCB design process, the layout of the components is extremely important, component layout is good or bad fundamentally determines the the PCB design level, performance parameters and a wiring difficulty degree, the layout, we must first determine the coordinate origin location of the PCB circuit board, general with single plate left and below the extension line intersection point or the single board left corner of the first pad is the origin of coordinates.
2, a PCB circuit board design, from determining the size of the board, the size of the printed circuit board (PCB) due to the chassis shell size restrictions to just ANN into the shell is appropriate; secondly, we should consider the PCB circuit board and external components (mainly potentiometer, Jack or another PCB circuit board) connection. The PCB circuit board and the external assembly are generally connected through a plastic wire or a metal isolation line. But sometimes it is designed as a socket. That is: install a plug-in PCB board Jack yaoliuchu as the contact position in the equipment. For larger components installed on the PCB circuit board, the metal attachment must be fixed to improve the vibration resistance and impact resistance.
3, wiring diagram design of the basic method
First of all, we need to fully understand the selected components and various socket specifications, size and area; the position of the components arrangement reasonable, careful consideration, mainly from the angle of electromagnetic compatibility, anti-interference and walk the line short, cross, power supply, road, diameter and decoupling considering. Each component position is set, that is, the various parts of the line, in accordance with the circuit diagram to connect the pin, complete the method of a variety of printed circuit design with computer aided design.
Line board should be how to be in line with the design requirements of it? Now let's go and see.
The first step, check the PCB circuit board
For any assembled PCB circuit board, before the test run, you must carefully check whether there is any error in the PCB line connection. Control the corresponding PCB schematic, according to a certain order of the corresponding inspection.
Second step, power through observation
Be sure to debug a good value for the power supply voltage, and determine the PCB circuit board power supply side without a short circuit phenomenon, in order to give the PCB circuit to switch on the corresponding power supply.
Third step, static debugging
Without adding any input signal, the measurement of DC operating voltage and current is normal.
Fourth step, dynamic debugging
By adding the input signal, the output signal of the PCB circuit is in accordance with the design requirements. In order to meet the design requirements, the PCB circuit board is adjusted to meet the design requirements, such as the communication channel components, such as the capacitor, the inductor, the waveform, the amplitude and the frequency of the AC signal of the PCB circuit.
The fifth step, the index test
PCB electronic circuit with static and dynamic adjustment of normal, at this time will be on the PCB circuit board for the corresponding test and record the test data, to test were used to analyze the data. Finally, it gives a conclusion of the test, so as to determine PCB circuit of the technical indicators are in line with the design requirements.
The PCB circuit board design is based on the circuit schematic diagram, realizes the function which the circuit user needs. PCB circuit board design mainly refers to the layout design, internal electronic components, metal wires, through hole and an external connection layout, electromagnetic protection, heat dissipation, crosstalk and other various factors. Excellent circuit design can save production cost, achieve good circuit performance and heat dissipation performance.
Layout principle of PCB circuit board:
1, according to the electrical performance of a reasonable partition, is generally divided into: digital circuit area (that is, fear of interference, and interference), analog circuit area (afraid of interference), power drive area (Gan Raoyuan);
2, the completion of the same function of the circuit, should be placed close to the place, and adjust the components to ensure that the connection is the most concise; at the same time, adjust the relative position between the functional blocks to make the connection between the functional blocks of the most concise;
3, for the quality of the components should consider the installation location and installation intensity; heating elements should be placed separately with the temperature sensitive components, it is necessary to consider the thermal convection;
4, I/O driver as close as possible to the printing plate edge, near lead connector;
5, the clock generator (such as: crystal oscillator or clock oscillator) device should be as close as possible to use the clock;
6, between each integrated circuit of the power input pin and ground, and a decoupling capacitor (usually with good performance of high frequency monolithic capacitor); space on the circuit board more dense, around several integrated circuit with a tantalum capacitor.
7, the relay coil to add discharge diode (1N4148 can);
8, the layout requirements should be balanced and orderly density, not top-heavy or a heavy head.