What are the important aspects of PCB design wiring process ?
In the design process of PCB, the wiring is divided into three types:
The first is butong, The second is satisfaction of electrical performance, Final one is aesthetics.
In wiring, the CAM OEM is mainly based on the following principles:
In general, the wiring of the power cord and ground wire should be prepared first to ensure the electrical performance of the circuit board.
Within the scope of the condition allows, you should try to widen the power, ground wire width, it will better if ground wire wide than the power cord, their relationship is: ground wire > power wire> signal lines, signal lines usually wide: 0.2 ~ 0.3 mm, the smallest width up to 0.05 ~ 0.07 mm, the power cord usually is 1.2 ~ 2.5 mm.
The PCB of a digital circuit can be used to form a loop with a wide field wire that is used to form a network. (analog circuits cannot be used in this way.)
In front of a line (such as a high frequency line) that requires a relatively strict line (such as a high frequency line), the edges of the input and output sides should avoid the adjacent parallel, so as to avoid reflection interference.
If necessary, geodesic isolation should be added. The wiring of the two adjacent layers should be perpendicular to each other.
The oscillator enclosure is grounded, the clock line is as short as possible, and cannot be used everywhere.The area of the special high speed logic circuit should be enlarged under the clock oscillator circuit, and other signal lines should not be taken to make the surrounding electric field close to zero.
The polyline of 45o shall be used as far as possible,, and 90o polyline should not be used to reduce the radiation of high-frequency signal;(the high line should also be double arc)
Any signal line should not form a loop, if inevitable, the loop should be as small as possible;The crossing of the signal line should be as low as possible;
The key line is as short and thick as possible, with a protective overlay on both sides.[PS: parcel place]
When transmitting sensitive signal and noise field signal through flat cable, the "ground wire - signal - ground wire" should be used.
Key signals should be reserved for test points to facilitate production and maintenance testing.
After the schematic wiring is completed, the wiring should be optimized;
At the same time, the initial network examination and DRC check after the ground for not wiring areas populated, with a large area of copper layer for ground, all the places are not used on the PCB as earth wire connected to ground.Or to make a multilayer board, power supply, ground line each occupy one layer.
The wiring should be neat and uniform, it can’t be crisscrossed without rules, It should be convenient for testing and maintenance.