Electromagnetic Compatibility, abbreviated as EMC, refers to an electronic device that neither interferes with nor is affected by other devices. Electromagnetic compatibility, like the familiar safety, is one of the most important indicators of product quality. Safety involves personal and property protection, while electromagnetic compatibility involves personal and environmental protection. The interference of electronic components to the outside world is called EMI (Electromagnetic Interference); Electromagnetic waves can interact with electronic components to produce interference, known as Electromagnetic Susceptibility (EMS). For example, the common "snowflakes" on TV fluorescent screens indicate that the received signal is interfered with. Because the shield plays a role in absorbing energy (eddy current loss), reflecting energy (reflection of electromagnetic waves at the interface of the shield), and canceling energy (electromagnetic induction generates reverse electromagnetic fields on the shield layer, which can partially offset interference electromagnetic waves) against external interference electromagnetic waves such as wires, cables, components, circuits, or systems, as well as internal electromagnetic waves, the shield has the function of reducing interference. When the frequency of electromagnetic interference is high, eddy currents generated in low resistivity metal materials are utilized to form a counteracting effect on external electromagnetic waves, thereby achieving shielding effect. When the frequency of interfering electromagnetic waves is low, materials with high permeability should be used to limit the magnetic field lines inside the shielding body and prevent them from spreading into the shielding space. In certain situations, if good shielding effect is required for both high-frequency and low-frequency electromagnetic fields, different metal materials are often used to form a multi-layer shielding body