Micromorphology analysis of Sn-3.0Ag-0.5Cu solder under compression in wide ranges of temperature and strain rate

The microstructure and mechanical properties of Sn-3.0Ag-0.5Cu (SAC305) under different working conditions were studied by static compression tests. The constitutive behaviour of SAC305 material with wide ranges of temperature and strain rate was obtained and correlated with the micromorphology on the specimen surface in this paper. With the temperature varies, the micromorphology of the solder specimens changed significantly. Specifically, as the temperature increases, more compression fringes along the loading direction appeared on the surface of the specimen, and the length of the fringes was elongated. Moreover, the mechanical properties of the solder showed obvious softening phenomenon, that is, the compressive strength decreased gradually. With the increase of the loading strain rate, the micromorphology showed the opposite evolution law compared with the consequences when the temperature increases. That is, the compression fringes gradually decrease and shorten, and the strength increased continuously, which shows an obvious hardening phenomenon. Under the condition of high temperature and low strain rate, a macro crack with the degree of 45° with respect to the compression axis can also be found on the surface of static compression specimen, and its length and width changed regularly with temperature and strain rate.