Introduction: PCB is known as the printed circuit board which can achieve the line connection and function realization between electronic components. It is also an important part of the power circuit design. Here are the basic rules of PCB board layout.
The basic rules of component layout
1. Layout is in accordance with the circuit module. The relevant circuit achieving the same function is a module; the components in circuit module should be used in the nearby centralized principle, while digital circuits and analog circuits will be separated;
2.3.5mm(For M2.5), 4mm (for M3) around the mounting hole like bolt may not be mounted on the components; 1.27mm around the non-mounting holes like position hole and standard hole should not be mounted with components and devices.
3. The bottom of sleeper resistance, inductance (plug-in), electrolytic capacitors and other components should avoid through-hole, preventing the short circuit between through-hole and component shell after wave soldering;
4. The distance between the outer side of the component and the board edge is 5 mm;
5. The distance between the outer edge of mounting element pad and the outside of the adjacent components is more than 2 mm;
6. Metal shell components and metal parts (shielding boxes, etc.) cannot be collided with other components, cannot be close to the printed line and pad, their spacing should be more than than 2mm. Positioning holes, fastener mounting holes, oval holes and other square holes in the board should be more than 3mm away from the board edge;
7. Heating components cannot be close to the wire and thermal components; high thermal devices should be balanced evenly;
8. Arranging as far as possible around the printed circuit board, the power outlet and the bus bar terminals connected to it should be arranged in the same side. In particular, do not place the power outlet and other solder connectors between the connectors to facilitate the design and bundle of these sockets, connectors and power cables. The layout of power outlet and welding connector should be considered to facilitate the power plug;
9. The layout of other components
All the IC components are aligned side by side; the polarity of the components should be marked clearly but shouldn’t be in more than two directions in the same printed circuit board, or the directions need to be perpendicular to each other;
10. The board wiring should be well-balanced and should be filled with mesh copper when the density difference is too large, and the gridding is more than 8mil (or 0.2mm);
11. The pad cannot have through-hole to avoid the poor solder paste in components. Important signal lines are not allowed to pass through the socket feet;
12. Pay attention to patch unilateral alignment and the character direction and packaging direction should be consistent;
13. The polarity mark of the device in the same board should be as much as possible consistent.
The component wiring rules
1. The distance from the wiring area to the PCB board edge cannot exceed 1mm, and the wiring is prohibited 1mm around installation hole
2. The power wire should be as wide as possible and not be less than 18mil; signal line width should not be less than 12mil; cpu input the output line should not be less than 10mil (or 8mil); line spacing is not less than 10mil;
3. The normal through-hole is not less than 30mil;
4, Dual in-line: pad 60mil, aperture 40mil;
1 / 4W resistance: 51 * 55mil (0805 surface); pad 62mil, aperture 42mil;
Promise capacitance: 51 * 55mil (0805 surface); pad 50mil, aperture 28mil;
5. The power and ground wire should be as radial as possible, and the signal line can not appear loop alignment.
How to improve the anti-jamming capability and electromagnetic compatibility when developing electronic products with processor?
1. the following systems should be paid special attention to anti-electromagnetic interference:
(1) Microcontrollers with particularly high clock frequency and fast bus cycles.
(2) System contains high-power and high current drive circuit, such as the spark production relay, high cur