Compression Force of a Form-In-Place (FIP) Conductive Elastomer EMI Shielding Gaskets: Theory, Measurement Techniques, and Application

The compression force of a FIP elastomer gasket during assembly and use is not a single number, but exhibits a dependence on the material, the method of measurement, and the conditions of use. FIP is a material which exhibits viscoelastic behavior and, as such, the gasket responds by deflection and creep to the dynamic forces incurred during assembly and the static forces present after assembly. Elements of part design also influence compression force. In practice, material hardness values have been used as to identify low compression force materials. The two properties, hardness and compression force, although correlated are not the same. Methods of measurement of compression force are described, with results presented for several types of FIP gasket. The preferred approach to evaluate the compression force of an FIP gasket is discussed.