The main purpose of adding electromagnetic shielding film to the PCB is to prevent the degradation of the electromagnetic compatibility (EMC) of the customer's electronic products, ensuring their stable operation and compliance with safety standards.
The core function of the electromagnetic shielding film is to control electromagnetic interference (EMI). Specifically, it includes: Firstly, it prevents external electromagnetic interference from affecting the internal circuits of the device. In complex electromagnetic environments, electromagnetic noise generated by surrounding components or wireless signals may couple through capacitive or magnetic coupling to interfere with sensitive components, causing signal distortion or functional abnormalities, as well as posing a risk to human health; The shielding film forms an isolation barrier by reflecting and absorbing external electromagnetic waves, ensuring signal integrity. Secondly, it suppresses the outward radiation of internal signals. High-speed or high-frequency signals (such as data transmission lines) may act like antennas and emit electromagnetic energy, interfering with adjacent devices or causing failure in system EMC tests; The shielding film can limit these radiations, reducing crosstalk and electromagnetic leakage.
Its working principle is based on the reflection, absorption, and cancellation mechanism of electromagnetic waves. The shielding film typically uses metal grids, conductive coatings (such as silver, copper, or ITO), or multi-layer composite structures. When electromagnetic waves strike the surface of the film, some of the energy is reflected, and the remaining energy propagates in the conductive layer due to eddy current losses and impedance mismatch, thereby weakening the interference field strength.
In practical applications, the electromagnetic shielding film has key advantages. For example, when used on flexible printed circuit boards (FPCs), it can adapt to the bending structure and provide a continuous conductive layer, effectively protecting high-speed interfaces or precise analog signals; At the same time, it can help the device meet industry EMC standards, avoiding compliance risks caused by electromagnetic leakage, and improving long-term operational reliability.
January 15th, 2026
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