Gasketing & Conductive Adhesives

Dontech provides many custom gaskets fitted to optical filter assemblies. Types of gaskets include environmental, conductive or combination (e.g., gaskets with both environmental and conductive properties). Mechanical requirements and required EMI/RFI attenuation levels and environmental requirements dictate gasket selection. Gasket material can be sized into a variety of shapes and thicknesses and attached to the filter perimeter via pressure sensitive adhesives, epoxies, and silicones. Additionally, conductive and nonconductive gaskets can be formed in place by applying the material directly to the optics or mounting assembly in a thixotropic form and then cured.

Environmental Gaskets
Environmental gaskets generally function to seal against moisture and dust. They may also be used to reduce shock and vibration in an assembly. Dontech most commonly uses neoprenes, silicones and urethanes for environmental gaskets. These materials are available with a range of physical properties for compliance with many different applications.

Conductive Gaskets
Conductive gaskets are primarily used to minimize the transfer impedance between conductive ground planes and to provide a continuous electrical seal between conductive, EMI/RFI shielding filters, and the mounting surface of the shielded enclosure. Conductive gaskets can be comprised of metal (e.g., knitted wire mesh, spring fingers, metal helicoils), conductively loaded form-in-place, strip or die cut elastomers and fabric-over-foam materials. EMI/RFI shielding is improved by minimizing the transfer impedance at the interface between the filter and the enclosure or bezel. Consequently mechanical, electrical, galvanic and thermal properties, as well as bus termination must be considered to optimize the performance of conductive gaskets.

Combination Gaskets
Combination gaskets are used to provide an electrical and environmental seal between the filter and enclosure. Two common configurations are gaskets with conductive elastomers (e.g., silver loaded silicone) and parallel environmental and conductive gaskets where a strip of conductive gasket is attached to a strip of a nonconductive elastomer.

For additional information on gaskets, please contact a Dontech applications engineer, or request that a hard copy of the Windows Design Guide be sent to you.