Techniques and mechanisms for providing effective connectivity with surface level microbumps on an integrated circuit package substrate. In an embodiment, different metals are variously electroplated to form a microbump which extends through a surface-level dielectric of a substrate to a seed layer including copper. The microbump includes a combination of tin and zinc that mitigates precipitation of residual copper by promoting the formation of miconstituents in the microbump. In another embodiment, the microbump has a mass fraction of zinc, or a mass fraction of tin, that is different in various regions along a height of the microbump.