PCB circuit board design and component wiring rules

The basic process of PCB circuit board design in SMT chip processing requires special attention. One of the main purposes of circuit schematic design is to provide a network table for PCB circuit board design and to prepare the basis for PCB board design. The design process of a multi-layer PCB circuit board is basically the same as the design steps of an ordinary PCB board. The difference is that the wiring of the intermediate signal layer and the division of the internal electrical layer need to be carried out. Taken together, the design of the multi-layer PCB circuit board is basically the same. Divided into the following steps:

1. Circuit board planning mainly involves planning the physical size of the PCB board, the packaging form of the components, the component installation method, and the board structure, that is, single-layer boards, double-layer boards, and multi-layer boards.

2. Working parameter setting, mainly refers to working environment parameter setting and working layer parameter setting. Correct and reasonable setting of PCB environment parameters can bring great convenience to circuit board design and improve work efficiency.

3. Component layout and adjustment. After the preliminary work is completed, the network table can be imported into the pcb, or the network table can be imported directly in the schematic diagram by updating the pcb. Component layout and adjustment are relatively important tasks in PCB design, which directly affect subsequent operations such as wiring and internal electrical layer segmentation.

4. Wiring rule settings mainly set various specifications for circuit wiring, such as wire width, parallel line spacing, safety distance between wires and pads, and via size. No matter what wiring method is adopted, wiring rules are necessary. An indispensable step, good wiring rules can ensure the safety of circuit board routing, comply with production process requirements, and save costs.

5. Other auxiliary operations, such as copper coating and teardrop filling, as well as document processing such as report output and save printing. These files can be used to check and modify PCB circuit boards, and can also be used as a list of purchased components.

Component routing rules

1. No wiring is allowed within the area ≤1mm from the edge of the PCB board and within 1mm around the mounting hole;

2. The power line should be as wide as possible and should not be less than 18mil; the signal line width should not be less than 12mil; the CPU input and output lines should not be less than 10mil (or 8mil); the line spacing should not be less than 10mil;

3. Normal via holes are not less than 30mil;

4. Dual in-line plug: pad 60mil, aperture 40mil; 1/4W resistor: 51*55mil (0805 surface mount); when plugged in, pad 62mil, aperture 42mil; electrodeless capacitor: 51*55mil (0805 surface mount); When inserted directly, the pad is 50mil and the hole diameter is 28mil;

5. Pay attention to that the power lines and ground wires should be as radial as possible, and the signal lines should not be routed in loops.