Pan Pacific Symposium Conference Proceedings


GAS PHASE FLUXLESS SOLDERING, CHEMISTRY AND APPLICATIONS

Authors: Stephen M. Bobbio, Thomas D. DuBois, and Robert F. Lipscomb
Company: The University of North Carolina at Charlotte, and Advanced Manufacturing Technologies LLC
Date Published: 1/31/2007   Conference: Pan Pacific Symposium


Abstract: Gas Phase Fluxless Soldering is a pretreatment for solder coated parts or solder preforms that can eliminate the use of flux, flux residues, as well as any unwanted physical effects resulting from the volatilization of flux components during reflow. The pretreatment exposes the parts to be soldered to a fluorinating gas that weakens the bonding between surface metal oxides (that prevent reflow and joining) and the underlying metal. The pretreatment is effective for a period of months and treated parts can be soldered with conventional equipment (e.g. solder wave or convection oven) without flux at any time during this period. If the joining process is rapid (e.g. thermode-type bonder) the reflow may be done in air. The gas phase pretreatment process leaves no residue. The fluorination chemistry reacts specifically at the interface between the metal and the metal oxide and therefore adds only one to two atomic layers to the surfaces of the parts. The fluorination uses a safe and easily handled gas source; and does not affect other materials (e.g. silicon and silicon oxides) that may be exposed during the pretreatment. The fluorination chemistry as well as process considerations and process tooling for the pretreatment will be discussed. Key words: fluxless soldering, solder reflow, fluxless pretreatment



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