In the design of PCB, there are three kinds of wiring:
It is cloth to pass first, it is the satisfaction of electrical performance next, it is beautiful next.
When wiring, CAM OEM and customer boards shall be mainly conducted according to the following principles:
(1).In general, the power cord and ground wire shall be first wired to ensure the electrical properties of the circuit board.As far as possible, the width of power supply and ground wire should be extended as far as possible, preferably with the ground wire wider than the power cord. Their relationship is as follows: the ground wire > power cord > signal line, usually the signal wire width is 0.2-0.3mm, the minimum width can be 0.05-0.07 mm, and the power cord is generally 1.2-2.5mm.The PCB of digital circuit can be used to form a loop with a wide ground wire, namely a ground network. (the ground of analog circuit cannot be used in this way.)
(2).In advance, the wire (such as high frequency line) with strict requirements shall be wired, and the side line of the input end and the output end shall be adjacent and parallel, so as to avoid reflection interference.When necessary, ground separation should be added, two adjacent layers of wiring should be perpendicular to each other, parallel easy to generate parasitic coupling.
(3).The oscillator housing is grounded, and the clock line should be as short as possible and not be triggered everywhere.Under the clock oscillating circuit, the part of the special high-speed logic circuit should increase the area of the ground, but should not go to other signal lines to make the surrounding electric field close to zero;
(4).As far as possible, 45o polyline should be adopted for wiring, and 90o polyline should not be used to reduce the radiation of high frequency signals.(the high-demand lines should be double-curved.)
(5).Any signal line should not form a loop. If it is unavoidable, the loop should be as small as possible.The signal line through the holes should be as few as possible;
6.The key lines should be as short and thick as possible, with a protective cover on both sides.[PS: land parcel]
All landowners.When transmitting the sensitive signal and noise field signal through flat cable, the signal shall be introduced by means of ground wire - signal - ground wire.
Today.Test points should be reserved for key signals to facilitate production and maintenance testing
Pet-name ruby.After the schematic wiring is completed, the wiring should be optimized.At the same time, after the initial network inspection and DRC inspection, the unwired area was filled with ground wire, and a large area of copper layer was used as ground wire.Or make multi-layer board, power supply, ground line occupied one layer each.
The wiring should be neat and uniform, not crisscross without rules and regulations, easy to test and maintain.