Bump and fabricating process thereof

摘要

A bump structure on a contact pad and a fabricating process thereof. The bump comprises an under-ball-metallurgy layer, a bonding mass and a welding lump. The under-ball-metallurgy layer is formed over the contact pad and the bonding mass is formed over the under-ball-metallurgy layer by conducting a pressure bonding process. The bonding mass having a thickness between 4 to 10 mum is made from a material such as copper. The welding lump is formed over the bonding mass such that a sidewall of the bonding mass is also enclosed.