Answer
Beryllium Copper (typically Alloy C17200) is selected for wave springs requiring high electrical conductivity and non-magnetic properties. It has an electrical conductivity of $15$-$25\%$ IACS, far exceeding stainless steels. In EMI shielding, the wave spring provides multiple contact points to ensure a low-impedance path to ground. Mechanically, CuBe can be hardened to levels comparable to alloy steels (up to $200$ ksi tensile strength). However, processing involves solution annealing followed by precipitation hardening at $600^{\circ}F$ for 2-3 hours. Engineers must account for its lower Modulus of Elasticity ($E \approx 124$ GPa), which requires thicker material or more waves to achieve the same load as a steel spring of the same dimensions.
