ABSTRACT
Mechanically formed metal gaskets can be dated back to the 1940s when spring clips were used to ground chassis in electronic equipment (Hudak, 2000). They have been widely used for EMI applications with high-traffic door opening and closing under compression or shear forces, wiping applications, and elevated temperature environments. The appeal of these gaskets results from their robust construction with various configurations and high level of shielding effectiveness. Metal-formed gaskets are usually made from high strength and conductivity spring alloys such as copper beryllium (CuBe), stainless steels, and copper-nickel-tin (CuNiSn) spinodal alloys. Gaskets made from CuBe alloys are most preferred due to their elastic resilience and highest electrical conductivity of all the conductive spring materials. Comparably, stainless steel provides a low-cost alternative to CuBe gaskets, which is particularly attractive in the commercial electronic industry. However, stainless steel gaskets are not recommended for high-cycling applications because stainless steel lacks the resilient spring properties of CuBe. They are suited for use in static joints and limited-access panels. In addition, spinodal CuNiSn alloys have been developed for making EMI gaskets and provide much better shielding effectiveness and spring performance than stainless steel.
