Materials Science is concerned with the development or synthesis of new materials . For this reason our interest is focused on the fabrication of new materials , such as lead free solder alloys . Sn-In alloys offer very low melting points and bond well with copper .This study aims to investigate The Structural and mechanical properties of (82-x)Sn -18In alloys with added copper .The Samples were prepared by melting technology From high purity (99 %) elements tin ,indium and copper .XRD showed the formation of a single phase hexagonal structure with a small copper plane, and the addition of copper decreased the particle size of the (82-x)Sn -18 In. The creep test results showed that Cu-containing solder alloys exhibited significant improvements in creep resistance. However, the average activation energy decreases with copper addition from 0.322 to 0.247 eV.