Shielding knowledge in the design of motherboard shielding cover

The shielding cover is an alloy metal cover, which is a vital component to reduce display radiation. It can effectively reduce the mutual interference between modules when used in MID or VR products. As shown in the figure, it is common in the main control function module and Isolation between the power supply module and the Wifi module. And what issues should be paid attention to in the design of the motherboard shielding cover? Generally, there are products that use wireless communication, and shielding frames are usually designed on the circuit board (to isolate electromagnetic interference (EMI), but for the shielding frame to function, two parts are generally needed, one is to use SMT The other is the shielding frame. In this case, more than two sets of press molds will be opened. The surface of the shielding frame is mostly hollow, which is directly welded to the main board. The shielding cover is buckled around and directly buckled On the shielding frame. It is convenient to remove the shielding frame without removing the shielding frame when disassembling and repairing. In the PCB design of MID or VR products, we often shield some modules 1. Power module ( PMU+DCDC+LDO) Usually the power module exists on the PCB as a heat source and interference source, and a shielding cover is added to it to effectively reduce its external radiation interference. 2. Core module (CPU+DDR+Flash[ EMMC]) The core module is the core part of the PCB. Stable and undisturbed operation is an important part of the stability of the system. As a module that is susceptible to external interference, a shielding cover is usually designed to shield it. 3. Wifi And Bluetooth module With the continuous increase of module integration, WiFi module also integrates many other functions, such as Bluetooth. The more integrated, it will naturally interfere with the reception of WiFi signals. Another main source of interference is the PCB board. Components and high-frequency circuits when they work will produce strong interference. At this time, most brand manufacturers will use shielding to remove or reduce the interference of the motherboard to the antenna. Metal shielding is a good choice, they can effectively shield The influence of electromagnetic waves on the internal circuit, of course, also blocks the electromagnetic waves generated inside from radiating outward. Of course, the position of the antenna is also more important. Generally, it is placed in a clean place on the side of the board. A Wifi Bluetooth module with a shielding cover is demonstrated. When designing the cover, try to avoid some irregular shapes and designs with large convex-concave drop as much as possible.