Abstract: A lead-free solder alloy comprising: from 1 to 9 wt. % copper, at least one of: from greater than 0 to 1 wt. % nickel, from greater than 0 to 10 wt. % germanium, from greater than 0 to 10 wt. % manganese, from greater than 0 to 10 wt. % aluminium, from greater than 0 to 10 wt. % silicon, from greater than 0 to 9 wt. % bismuth, from greater than 0 to 5 wt. % indium, from greater than 0 to 1 wt. % titanium, from greater than 0 to 2 wt. % lanthanum, from greater than 0 to 2 wt. % neodymium, optionally one or more of: up to 1 wt. % for chromium, gallium, cobalt, iron, phosphorous, gold, tellurium, selenium, calcium, vanadium, molybdenum, platinum, magnesium; up to 5 wt. % silver, up to 1 wt. % zinc, up to 2 wt. % rare earth metals, excluding lanthanum and neodymium, and the balance tin together with any unavoidable impurities.

Abstract: A process is described that enables the active side of a bumped wafer to be coated with a front side protection (FSP) material or wafer level underfill (WLUF) without contaminating the solder bumps with the coating material and/or filler. In this process a repellent material is applied to a top portion of the solder bumps on the active side of the wafer, the front side of the wafer is then coated with the coating material, the coating material is hardened, and optionally the repellent material is removed from the solder bumps.