Patent ID: 8278144

Claim:
A method of making a flip-chip semiconductor device, comprising: providing a substrate having a plurality of traces formed over a surface of the substrate, the surface of the substrate being non-wettable with respect to bump material; forming a masking layer over the surface of the substrate, the masking layer including a plurality of parallel elongated openings, the masking layer allowing a flow of bump material along a length of the plurality of traces within the plurality of elongated openings and preventing flow of the bump material past a boundary of the plurality of elongated openings, the plurality of elongated openings defining a plurality of interconnect sites on the plurality of traces, and wherein both first and second traces of the plurality of traces are exposed by both first and second elongated openings of the plurality of elongated openings and the first and second traces are parallel with respect to a width across the first elongated opening along the first and second traces and the first and second traces are angled with respect to a width across the second elongated opening along the first and second traces; disposing a semiconductor die over the substrate with contact pads formed on the semiconductor die aligned with the plurality of interconnect sites; disposing a no-flow underfill material between the semiconductor die and the substrate; and connecting the contact pads of the semiconductor die to the interconnect sites with composite bumps including a fusible portion and a non-fusible portion by, (a) thermo-mechanically joining the fusible portion of the composite bumps to the interconnect sites without melting the fusible portion, (b) curing the no-flow underfill to a gel stage, and (c) reflowing the fusible portion to form an interconnection between the composite bumps and interconnect sites.