Shielding is the use of shielding to surround the source of interference from components, circuits, assemblies, cables, or the entire system. Shielding boxes are classified into pneumatic shielding boxes, manual shielding boxes, and semi-automatic shielding boxes according to the operation mode. According to applicable products and frequency points, it includes Bluetooth shielding box, WiFi shielding box, GPS shielding box, etc.
Electromagnetic interference/EMI is a problem that must be faced and overcome in the entire electronic field, generally in wireless communication products such as: mobile phones, wireless network cards, wireless routers, wireless headsets, Bluetooth headsets, wi-fi, wimax, data cards, walkie-talkies, RFID, etc. In the process of board testing and final testing, such as wireless communication equipment and wireless communication modules, they all use radio frequency test shielding boxes to improve the test environment.
The structure of the shielding box mainly consists of a box body, absorbing materials, filters, host and other materials. The absorbing materials and filters mainly absorb electromagnetic waves in the box to prevent internal and external interference. The host mainly controls the switch and other functions of the shielding box. The use of shielding box needs to confirm the working frequency and some important parameters to ensure that it can be used. Conduction is a key part of the shielding box processing. When the product is placed in the shielding box for testing, it must communicate with the outside world through the interface, and it needs to be connected to the test instrument. If the interface filtering is not good, the RF line of the connected instrument will become an antenna, and the signal will be imported into the shield. Inside the box, there is no shielding effect, and the isolation is extremely reduced. The test also cannot feedback accurate data. Therefore, the key to the isolation of the shielding box is the interface processing, and the interface filtering methods are different for different tested product frequencies.
The principle of the shielding box is to use a shield to surround the components, circuits, assemblies, cables or interference sources of the entire system to prevent the interference electromagnetic field from spreading; use the shield to surround the receiving circuit, equipment or system to prevent them from being exposed to the external electromagnetic field influences. The mobile phone shielding box material usually uses 0.2mm thick stainless steel and nickel silver as the material. Among them, nickel silver is a kind of metal shielding material that is easy to be tinned. The suction cup design should be considered when using SMT stickers. The flatness of the mobile phone metal shielding box is strictly controlled within the tolerance range of 0.05mm to ensure its easy tinning performance and optimize the shielding effect.
The shielding box is mostly used in production testing, which improves the testing efficiency and reduces the fatigue of the operator. Test mobile phones, notebooks, PAD and other equipment have corresponding size equipment.