environmental effect principle
Pay attention to the applied environment, for example, in a vibration or other environment that is easy to deform the board, it is easy to peel off the copper film wire if it is too thin.
Safe Work Principles
To ensure safe work, for example, to ensure the minimu distance between the two lines to withstand the peak voltage applied, the high-voltage lines should be smooth, without sharp chamfers, otherwise it is easy to cause board breakdown, etc.
Easy assembly, standard principles
Wiring design should consider the convenience of assembly. For example, when there are large-area ground wires and power wires (more than 50O square millimeters) on the printed board, some windows should be opened so that
for corrosion etc.
In addition, assembly specification design should also be considered. For example, a component's solder joints are represented by pads, and these pads (including vias) will automatically be free of solder paste. However, if filler blocks are used as surface pads, or wire segments are used as gold finger plugs without special treatment (drawing areas without solder mask oil on the solder mask layer), solder mask oil will cover these pads and gold fingers. Fingers, it is easy to cause misunderstanding; when the pins of SMD devices are connected to large-area copper cladding, heat insulation should be carried out. Generally, a track should be made on the copper foil to prevent stress concentration caused by uneven heating.
Cause false soldering; if there is any solder on PCB412 or square through holes larger than 12mm, hole covers must be made to prevent solder from flowing out, etc.
economic principles
Following this principle requires the designer to have sufficient knowledge and understanding of the processing and assembly process. For example, it is more difficult to corrode a 5mil line than an 8mil line, so the price is higher, and the smaller the via hole is, the more expensive it is, etc.
thermal effect principle
The following methods can be considered in the design of printed boards: evenly distribute heat loads, install radiators on parts, and force air cooling locally or globally.
From the perspective of facilitating heat dissipation, it is best to install the printed board upright, and the distance between the board and the board should generally not be less than 2cm, and the arrangement of the devices on the printed board should follow certain rules:
The same—the devices on the printed board should be arranged according to their calorific value and heat dissipation degree as much as possible. Devices with small calorific value or poor heat resistance (such as small-signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) should be placed in the cooling airflow At the top (at the entrance), devices with high heat generation or good heat resistance (such as power transistors, large-scale integrated circuits, etc.) are placed at the bottom of the cooling airflow.
In the horizontal direction, the high-power devices should be placed as close as possible to the edge of the printed board in order to provide a short heat transfer path; in the vertical direction, the high-power devices should be arranged as close as possible to the top of the printed board in order to reduce the impact of these devices on other devices during operation. The effect of temperature.
Devices that are sensitive to temperature are best placed in the area with the lowest temperature (such as the bottom of the device). Never place it directly above the heat-generating device. It is best to arrange multiple devices staggered on the horizontal plane.
The above four articles are all about the principles of PCB layout. There are many contents, but they are all dry goods. I hope this knowledge can answer some confusions for you!
