Meaning
Surface treatments formulated with metallic particles provide the shielding needed to block electromagnetic interference in non-conductive plastic enclosures. Applying a conductive coating to the interior walls of a device housing transforms an inexpensive plastic shell into an effective electromagnetic barrier. This method prevents external signals from disrupting internal circuits and limits radiated emissions from the device itself.
The effectiveness of the treatment is limited by the thickness of the application and the coverage of joints and apertures.
Material Properties
Formulations containing nickel, silver, or copper particles are selected based on the required attenuation levels and cost constraints. These paints or spray coatings form a continuous conductive path when cured. The choice of metal determines the resistance of the cured surface.
Application Process
Precision spraying ensures that the material is distributed evenly across all interior surfaces without clogging mounting bosses or threaded inserts. This process must be controlled to prevent thin spots that would allow electromagnetic leakage. Specialized masking is used during manufacturing to keep essential interface areas free of paint.
The cured layer must adhere well to the plastic substrate to avoid flaking over time.
Shielding Effectiveness
Attenuation performance depends on the continuity of the conductive layer across seams. Any gaps or fractures in the coating will degrade the shield. This makes post-curing resistance tests a major quality control step.
