Changes

The increasing requirements on spring components in connectors, especially for use in automotive applications, such as higher surrounding temperatures, increased reliability, and the trend towards miniaturization led to a change of materials from traditionally CuZn30 and CuSn4 to CuNiSi alloys, for example. These CuNiSi alloys and the newer heavy duty copper alloys like CuNi1Co1 are significantly improved with regards to mechanical strength, relaxation behavior, and electrical conductivity.

Technical grade pure nickel commonly contains 99.0 to 99.8 wt% Ni and up to 1 wt% Co. Other ingredients are iron and manganese ''(Tables 5.21 and 5.22)''. Work hardening and softening behavior of nickel are shown in Figs. 5.45 and 5.46.

Because of its low electrical conductivity NiCu30Fe is besides pure Ni and CuNi alloys the most widely used backing material for weldable contact components. With 1 – 2 wt% additives of Fe as well as 0.5 – 1 wt% Mn and Co the mechanical strength of the binary alloy NiCu30 can be increased.

Because of decreasing solubility of beryllium in nickel with decreasing temperature NiBe can be precipitation hardened similar to CuBe ''(Fig. 5.49)''. The maximum soluble amount of Be in Ni is 2.7 wt% at the eutectic temperature of 1150°C. to achieve a high hardness by precipitation hardening NiBe, similar to CuBe, is annealed at 970 - 1030°C and rapidly quenched to room temperature. Soft annealed material is easily cold formed and after stamping and forming an hardening anneal is performed at 480 to 500°C for 1 to 2 hours.

hardening of NiBe2

(soft) at 480°C

===5.3 Triple-Layer Carrier Materials===