Aluminum foil Mylar is a composite material consisting of aluminum foil and polyester film (Mylar).
I. Main characteristics of aluminum foil Mylar: 1) Excellent barrier properties. Aluminum foil Mylar exhibits excellent barrier properties, effectively blocking moisture, oxygen, light, and electromagnetic waves.
2) High strength and durability: The addition of polyester film enhances the mechanical strength of aluminum foil Mylar, enabling it to withstand certain levels of stretching and tearing.
3) Lightweight and easy to process: Aluminum foil Mylar is lightweight, making it easy to transport and process.
4) Electrical conductivity and electromagnetic shielding performance: The electrical conductivity of aluminum foil makes it widely used in the electronics industry for electromagnetic shielding, protecting sensitive equipment from interference.
II. The orientation (inward or outward) of the aluminum foil shielding layer of the cable directly affects its electromagnetic shielding effect:
1) When facing inward, the aluminum foil comes into direct contact with the wire core, absorbing the electric field energy on the conductor surface through the image charge effect, reducing near-field radiation by 10-15dB.
2) When facing outward, the aluminum foil serves as the first shielding layer, with a reflectivity of over 90%, improving the attenuation of external magnetic field interference by 20%-30%.
3) Prefer inward orientation: Scenarios where the signal frequency is greater than 1GHz and strict control of radiated emissions is required (such as EMC Class B standards).
4) Prefer facing outwards: In scenarios where there is strong external interference (such as an electric field strength of 10kV/m), frequent bending, or grounding is required.
5) Composite shielding: When EMC requirements are stringent, a double-layer structure consisting of “inner aluminum foil + outer copper braiding” is adopted, with a shielding effectiveness >120dB (1GHz).