Patent ID: 8614512

Claim:
A solder ball contact, comprising: a first insulating layer disposed on an integrated circuit (IC) chip and a metal pad, said first insulating layer including a via to said metal pad; an under bump metallurgy (UBM) structure disposed on sides of said via, on a top surface of said metal pad, and on a portion of a top surface of said first insulating layer, surrounding said via; a second insulating layer disposed on an upper surface of an outer portion of said UBM structure that is centered on said via; and a solder ball that fills said via and is disposed above said upper surface of an inner portion of said UBM structure that contacts said via, said second insulating layer having a vertical inner surface and a vertical outer surface, wherein said vertical inner surface of said second insulating layer is aligned with a vertical inner top surface portion of said UBM structure, wherein said vertical outer surface of said second insulating layer is aligned with a vertical outer bottom surface portion of said UBM structure, said second insulating layer having an inner edge that delimits a diameter of said solder ball, and said solder ball having the diameter that is 60% to 90% an outer diameter of said UBM structure.