Research on tin whisker growth of pure tin plating of different lead substrates

Abstract

To study the tin whisker growth behavior of different lead substrates, five kinds of lead frames were designed as plating substrates and the pure tin were electroplated onto the substrates respectively, then the thermal shock, high temperature/humidity storage, and the ambient temperature/humidity storage test were performed under the annealing and un-annealing conditions, and the effect of lead substrates on the crystal structures of Sn plating was analyzed and the influence of environment condition, crystal structure, annealing process on the tin whisker growth was studied. The results showed that the Sn plating of brass frame was easier to grow tin whisker than other lead frames because of bigger crystal sizes and smaller boundary interspaces of grains, The temperature change condition was the best external driving force, The capability of anti-tin whisker was excellent for Sn plating of C7025 substrate plating, and the external environment had a great impact to the tin whisker growth of 42 alloy substrate plating. At last, the annealing process was available to slow down the growth of tin whisker under isothermal condition.