1. The principle of the shortest route: the shortest route can be as short as possible, the simplest principle is also the most important principle. This is your board function
Decisive factor for stability.
2. Component layout, connector must consider the location, everyone''s DB9 drawing on the board did not consider whether your serial cable can be inserted. If you add usb, you must also consider the location. After the layout of the Pcb is completed, you can print it out 1: 1 and put it in the original to try it out.
3. Component layout. Components with electrical connections should be as close as possible. For example, the four capacitors of max232 need to be placed around max232 so that the shortest wiring can be achieved. Consider changing the layout of the components.
4. The thickness of the signal line is generally designed to be 10mil (about 0.2mm), and the power line is at least 25mil, preferably 30mil, because the larger the current, the wider the line width, the larger the current line current, and the smaller the signal line current.
5. The via size is generally set to 12-24mil (inner diameter-outer diameter)
6. The line must not be a 90-degree line. The reason is simple. Show me a 90-degree turn if you ride a bike fast? Turn the line at 45 degrees.
7. Crystal oscillator, as the heart of single-chip microcomputer, must be as close as possible to the chip. The minimum system of single-chip microcomputer we designed, in addition to the single-chip microcomputer has a crystal oscillator, as well as the chip with USB to serial port has a crystal oscillator.
8. USB to serial port must be available, which can solve the problem of power supply and program download
9. As an indispensable part of pcb, copper must be provided, and the area of copper should be as large as possible, and a complete piece of copper should be covered as much as possible.
10. When covering copper, the vias should be completely connected with the copper you covered, and the pads should be connected to the copper with 4 wires, because if the pads are also completely connected to the copper, the heat dissipation during soldering will be too fast, which can easily lead to false Solder, while vias are only used to connect wires, not solder.
11. Your board must be sent to the processing plant at the end. Whether you do PCB in the company or make your own board, you must consider the cost. The board area is controlled at 10 * 10cm.