First, the basic rules of component layout

1. According to the circuit module layout, to achieve the same function of the relevant circuit is called a module, the circuit module components should be used in the nearest centralized principle, while digital circuits and analog circuits separately;
(For M2.5), 4mm (for M3) may not be mounted on the components; the positioning hole, the standard hole and other non-mounting holes around 1.27mm within the mounting element,
3. Sleeve resistance, inductance (plug-in), electrolytic capacitors and other components to avoid the bottom of the hole, so as not to wave after welding hole and component shell short circuit;
4. The distance between the outer side of the component and the edge of the board is 5mm;
5. The outside of the mounting element pad is greater than 2 mm from the outside of the adjacent cartridge member;
6. Metal shell components and metal parts (shielding box, etc.) can not be touched with other components, can not close to the printed wire, pad, the spacing should be greater than 2mm. Positioning holes, fastener mounting holes, oval holes and other square holes in the board from the side of the board size is greater than 3mm;
7. Heating element can not be close to the wire and thermal components; high-temperature devices to be balanced distribution;
8. The power outlet should be arranged around the printed circuit board as far as possible, and the busbar terminal connected to the power outlet should be arranged on the same side. In particular, be careful not to place the power outlet and other solder connectors between the connectors to facilitate the design of these sockets, connectors and power cables. The layout of the power outlet and the welding connector should be considered to facilitate the plug of the power plug;
9. Other components of the layout:
All the IC components are aligned side by side, the polarity of the polarity of the components marked clearly, the same printed circuit board polarity mark not more than two directions, there are two directions, the two directions perpendicular to each other;
10, board wiring should be well-balanced, when the density difference is too large should be filled with mesh copper, the grid is greater than 8mil (or 0.2mm);
11, the patch pad can not have through-hole, so as not to cause the loss of solder paste components Weld. Important signal lines are not allowed to pass through the socket feet;
12, patch unilateral alignment, the same character direction, the same direction of packaging;
13, the polarity of the device in the same board on the polarity marked as much as possible consistent.

Second, the component wiring rules

1, the design of the wiring area from the PCB board edge ≤ 1mm area, and the installation hole around 1mm, prohibit wiring;
2, the power cord as wide as possible, should not be less than 18mil; signal line width should not be less than 12mil; cpu into the outlet should not be less than 10mil (or 8mil); line spacing of not less than 10mil;
3, the normal hole is not less than 30mil;
4, double inline: pad 60mil, aperture 40mil;
1 / 4W resistance: 51 * 55mil (0805 surface); lead pad 62mil, aperture 42mil;
Promise capacitance: 51 * 55mil (0805 surface); lead pad 50mil, aperture 28mil;
5, pay attention to the power cord and ground should be as radial as possible, and the signal line can not appear loop alignment.