Tacky Dots/sup TM/ transfer of solder spheres for flip chip and electronic package applications

Investigation of a solder bumping technique for flip‐chip interconnection

“…In particular, the use of solder paste provides a relatively low cost source of solder and the technology and infrastructure to print solder paste and place and align wafers is already available in most stencil printing machines. This route also has potentially limited environmental impact, comparable to conventional stencil printing, but with significant advantages over alternative processes that require imaging and development of photoresists (Salonen and Salmi, 1994) or the disposal of used carrier materials such as polyimide tapes (Hotchkiss et al, 1998).…”

“…A number of similar processes for mass bumping use the placement of solder balls on to or into a carrier. This carrier matches the bondpad layout and holds the solder in place against the wafer during reflow (Ramos, 1998;Fujino et al, 1998;Hotchkiss et al, 1998;Lin, 1993). Many of these methods appear to have their origins in the solder ball bumping of BGA and CSP components (Ramos, 1998); however, the extension of these technologies to flip-chip geometries is non-trivial due to the reduced size of the single solder particles.…”

Investigation of interfacial reaction between eutectic Sn–Pb solder droplet and Au/Ni/Cu pad

“…Many bumping technologies have been developed. [1][2][3][4][5] Molten droplet solder bumping as a new type bumping method was developed in recent years, with several different technologies available to form the molten droplet. 6,7 Basically, the molten solder is dropped onto the metallisation pad at high temperature.…”