Solder Ball Pad Structure

An interconnect structure a substrate, a contact pad disposed over a surface of the substrate, and an insulative mask disposed over the contact pad. The insulative mask can include an opening that is aligned over and exposes an inner portion of the contact pad. The inner portion of the contact pad includes a compliant layer and a conductive layer that is disposed over the compliant layer. The inner portion of the contact pad has sufficient flexibility to distribute mechanical stress applied to the contact pad and can mitigate damage to the interconnect structure.