How to solve the electromagnetic interference caused by pcb multilayer circuit board?
When the small relay on the PCB frequently disconnects from the large current, the phenomenon of arc discharge will occur, resulting in strong electromagnetic interference, which not only affects the CPU, but also causes the decoder and driver to generate wrong signals and instructions, causing a series of problems. The following are some solutions to electromagnetic interference caused by frequent actions of small relay of PCB multilayer circuit board:
1) improve chip anti-interference ability: CPU of PCB multi-layer circuit board is replaced by super anti-interference chip. The porcelain decoupling capacitance should be installed between the CPU and the power port of the decoder. The grounding end should be as close to the chip as possible. Shorter pins are much better.
2) suppression of interference source: relay driving amplifier adopts darlington IC module with continuous current function (such as ULN2004A), which can effectively eliminate interference caused by reverse electromotive force when the coil is cut off. In addition, the PCB multilayer circuit board can effectively prevent electromagnetic interference by selecting the appropriate relay or coating the PCB with copper foil of medium thickness. (Halogen Free PCB manufacturer china )
The opening length or width of PCB multilayer circuit board template can be reduced by 10%~30% compared with the size of the solder pad, so as to reduce the deposit of solder paste. The opening shape of the template is in a selected form to reduce the amount of paste deposition on the narrow pitch pad. Choose an eclectic template thickness that is suitable for both narrow pitch and non-narrow pitch pads to replace different pads that require different template thicknesses.