EMI Shielding Materials

EMI Conductive Coatings & Fine Wire Mesh

Conductive optical ground plane options include transparent conductive coatings and conductive optical grids. These conductive ground planes can be applied to the surfaces of glass, plastic, and crystalline substrates. Conductive materials can be laminated between two substrates, and they can be embedded below thick film coatings. Typically, the conductive ground plane is integrated into the next higher level assembly by terminating the coating or grid via a conductive busbar, gasket, tape, or by extending mesh or foil, to the frame, bezel, or conductive enclosure.

Dontech optical EMI/RFI shielding products are as follows:

• Transparent Conductive Coatings
  • Transparent Conductive Oxides (TCOs)
    • ITO coatings
    • Custom
  • Metallic and Metal Alloy
    • Au
    • Ag
    • Cu
    • Metal Alloys
    • Custom
• Conductive Optical Grids
  • Etched and Patterned Conductive Coatings
    • MEM Mesh Etched Thin Film Coatings
    • Printed or Patterned Conductive Materials
  • Plated Woven Meshes
    • Stainless Steel Meshes
    • Copper Meshes
    • Custom Meshes
    • Custom Conductive Plating
    • Unplated Meshes

Transparent Conductive Coatings

Dontech has an extensive array of high energy vacuum deposition systems for applying thin film transparent conductive coatings to different types of glass, plastic (polycarbonate, acrylic, PET plastic), and crystalline substrates. Typical conductivities for transparent conductive coatings for EMI RFI shielding range from < 1 ohm/sq on ITO coated glass to >50 ohms/sq, providing low to moderate levels of shielding.

The most prevalent transparent conductive coating is indium tin oxide (ITO) and it can be applied to different types of glass, crystalline and plastic substrates. Conductive coatings and substrate surfaces can be dielectrically enhanced, often referred to as index matching, to maximize light transmission by controlling interface reflections. Through this process, reflection losses are converted to transmitted light. Dontech can index match conductive coatings to air (n=1), to the optical substrates (typical: n= 1.41 through n = 2.44), or to an optical adhesive (typical: n=1.41 through n = 2.36). ITO coatings offer excellent optical properties (>97% VLT – conductivity and substrate dependent) and excellent environmental durability with low to moderate levels of shielding.

Dontech designs and applies conductive coatings on both rigid and flexible substrates in both roll-to-roll (R2R) and batch thin film coating processes. We customize our coatings for the optical spectrum, covering Visible through Near IR. For both longer wavelengths such as the Mid IR through Far IR and for higher shielding applications, Dontech offers conductive optical grids.

Conductive Optical Grids

Dontech manufactures shielding solutions with conductive optical grids for displays and precision optics applications. Dontech’s optical fine wire (OFW) meshes, and micro etched mesh (MEM) combine excellent shielding effectiveness with optical performance, making them ideally suited for electronic displays and often the only solution for precision optics applications. The MEM products are produced by removing (e.g., etching) part of the conductive coating (e.g., Cu) or applying the coating in a pattern (e.g., printing). The conductive layer can be applied through a direct deposit to the substrate of choice or via a carrier layer to reduce costs. Standard Dontech MEM display products are available from 80 through 160 openings per inch, allowing for a broad range of both shielding and optical solutions. For precision optics, the conductive material, pitch, line width, orientation, pattern shape (within limitations) and the conductivity (typically controlled by the thickness) can be adjusted based on customer requirements. Setup charges can be significant for unique formats. For this reason, it is typical for projects to be designed around existing formats.

Dontech produces high uniformity optical fine wire (OFW) meshes (e.g., copper or stainless steel woven mesh) for high performance EMI/RFI shielding applications. Dontech OFW mesh has typical wire diameters of 0.0011”, 0.0012”, or 0.0022” and is typically created in a plain weave with either square or rectangular apertures. Dontech’s weaving looms have been specially tooled to allow for high uniformity and transmission, which is important for both moiré control and aesthetic purposes. The wire mesh is conductively electroplated, which fuses the wire crossovers and results in improved uniformity and conductivity of the mesh while also minimizing surface reflections. Additionally, the outer plating layer is conductive and corrosion resistant, greatrly improving the galvanic stability of the material. Standard Dontech woven mesh is available from 50 through 255 openings per inch, allowing for a broad range of both shielding and optical solutions. Custom OFW is available; however, setup charges can be significant for unique formats. For this reason, it is typical for projects to be designed around existing formats.

For display applications, Dontech conductive optical grids can be custom oriented to produce the best optical results. Follow the link to moiré control for a summary on an optical fitting process with conductive optical grids.

For EMI/RFI shielding applications, conductive ground planes are typically grounded via a perimeter busbar, gasket, or tape to help terminate the optical conductive ground plane to the rest of the Faraday Cage. Dontech’s EMI/RFI shielding optical filters can be supplied with conductive gaskets, tapes, and mounting frames. Conductive gaskets include form in place, strip, and die cut conductively loaded elastomers, metalized fabric over foam, and metal-based gaskets (e.g., finger stock, knitted mesh gaskets).