Richard E. Patrick

Electron Attachment: A New Approach to

Wafer bumping, via fluxless solder reflow, can be performed using electron attachment (EA) with nonflammable mixtures of hydrogen (= 4 vol%) in nitrogen. The EA process facilitates dissociation of molecular hydrogen at ambient pressure and a temperature significantly lower than that of thermal dissociation. Our studies suggest that the EA process promotes the formation of atomic hydrogen anions, which reduce solder oxides and facilitate fluxless solder reflows at temperatures close to the solder melting point.

{\rm H} _{2}

A novel hydrogen activation technology based on electron attachment (EA) is developed for fluxless soldering at ambient pressure and normal soldering temperature. The technology has a potential to be used for a list of applications in the electronics packaging industry.

Fluxless Solder Reflow for Wafer Bumping

This paper introduces a recent work by a joint effort between Air Products and Sikama International on alpha trials of a production-scale furnace for flux-free wafer bump reflow based on electron attachment (EA).