EMI shielding gaskets such as conductive elastomer gaskets come in many different materials and almost a limitless number of shapes and sizes.
They are most commonly made of a base material of silicone or fluorosilicone with added conductive fillers such as silver, silver-plated aluminum, nickel-plated graphite, and others. Conductive elastomers represent one of the most versatile products in the category of EMI shielding gaskets.
From a manufacturing perspective, there are two key processes used to create these gaskets: splicing and molding. Check out the detailed list below for information about choosing the process that makes the most sense for you.Conductive elastomer gasket splicing
Conductive elastomer gaskets are often extruded in long strips, available in bulk or cut to specific lengths. To create custom sized O-rings, the extrusions are cut to the proper length and the ends are adhered (fused) together. Known as splicing, this process utilizes a proprietary adhesive to create an immensely strong bond.
- Bulk material relatively easy to extrude in long lengths, splicing is a process that can allow for quicker turnaround.
- Hundreds of standard extrusion profiles made to match almost any current design requirements.
- When O-ring sizes or design requirements change, splicing can accommodate these changes usually without significant lead time or cost.
- Requires very little or no tooling, meaning low upfront capital investment.
- Can be used with hollow cross-section profiles, creating parts that can accommodate low compression force enclosures.
- Limited in their complexity to singular “loops”.
- Will not retain their shapes like molded O-rings.
- Will not hold to tight tolerances that are common in molded parts.
- There is a limit to how small, in length, gaskets can be spliced.
Molding involves compressing uncured conductive elastomer material into a specially designed mold. The material takes the shape of the mold and retains this shape when cured.
- Allows for a great deal of complexity in parts which can include multiple joints and variability in cross sections across a single part.
- Hold tolerances to within a few thousandths of an inch.
- Will retain the shape in which they were molded.
- In high volumes, molded gaskets can cost less than spliced gaskets as the manual labor is minimized and the process is optimized.
- Can be made in very small o-rings and parts.
- Unless molded gaskets match industry standard gaskets that are commonly available, each new gasket will require a new mold.
- Not compatible with hollow gaskets – molded gaskets cannot have hollow cross sections like spliced extrusions.
- Very large diameters, in length, are not economical.
Between molding and splicing, there is virtually an endless number of profiles and shapes that can be developed. For more information on choosing and designing an EMI shielding gasket, check out the Conductive Elastomer Handbook below.
This blog post was contributed by Ben Nudelman, market development engineer, and Scott Casper, applications engineer, Chomerics Division.