Patent ID: 8436470

Claim:
An assembly comprising: a circuit board; a device including a package substrate and an integrated circuit (IC) die disposed on a first side of the package substrate; and a number of interconnects electrically coupling the device with the circuit board, each interconnect extending between an opposing second side of the package substrate and a surface of the circuit board; wherein at least one of the interconnects includes a first area to receive a solder ball disposed on the second side of the package substrate; a first surface finish disposed in the first area, the first surface finish including nickel and phosphorous; a second area to receive a solder ball disposed on the surface of the circuit board; a second surface finish disposed in the second area, the second surface finish including nickel and phosphorous; and a reflowed solder bump coupled with the first surface finish and with the second surface finish, the reflowed solder bump including tin, silver, and copper, wherein the reflowed solder bump forms an intermetallic with at least one of the first and second surface finishes, the intermetallic including nickel, phosphorous, tin, and silver, with the balance being an amount of copper that is greater than the amount of copper present in a bulk of the solder bump.