Dontech designed and produced optical display components to help upgrade an LCD to achieve TEMPEST compliance on a large Command and Control display for a Certified TEMPEST Manufacturer. The EMI/RFI filter incorporated a polycarbonate substrate and embedded Dontech conductively plated mesh for shielding and filtering of EMI/RFI susceptibility to address the higher-than-normal shielding effectiveness requirements of this application.
Our design balanced optical transmission requirements while also providing sufficient surface area of very high electrical conductivity for optimal radio frequency shielding and included termination with both conductive bus bars and gaskets. This design used mesh with 80 openings per inch type 304 stainless steel, silver plated (fusing the wire crossovers), blackened to resist corrosion and improve contrast. Mesh orientation and uniformity were tightly controlled to eliminate optical interference (moiré) with the LCD pixels.
These unique Dontech controls enabled the TEMPEST manufacturer to achieve better optical performance by using mesh with higher open area and optical transparency while still meeting the stringent TEMPEST shielding requirements. Reflection control was achieved through a Dontech applied broad band antireflective (AR) coating with low specular reflection properties to control first surface reflections to greatly improve the readability of the display. The conductive ground plane was terminated with a silver bus bar and conductive gasket to minimize the transfer impedance, thereby completing the Faraday cage, and yielding a high-performance shielded display monitor enclosure.