Because of their good elastic spring properties and formability the copper-tin alloys CuSn6 and CuSn8 are standard materials for spring contact elements in electrome-chanical components such as connectors, switches, and relays ''(Tables 5.9 and 5.10)''. Besides these other alloys such as CuSn4 and CuSn5and the multi-metal tin bronze CuSn3Zn9 have significant usage – mainly in North America.Figure 5.10 shows the copper rich side of the phase diagram for the CuSn system. The mechanical property values achieved by cold forming are superior to these of the brass alloys ''(Fig. 5.11)''. They increase significantly with increasing Sn content. The work hardening and softeningbehavior are shown for the example of CuSn8 in Figures 5.12 and 5.13. The stress relaxation properties for CuSn alloys are good for up to 100°C, deteriorate however quickly for temperatures above 150°C.