Furnace and Infrared Soldering

Furnace soldering (FS) encompasses a group of reflow soldering techniques in which the parts to be joined and preplaced filler metal are put in a furnace and then heated to the soldering temperature. This article describes three reflow soldering techniques in surface-mount technology, namely, vapor-phase reflow, area conduction, and infrared heating. These three techniques are considered as mass reflow techniques, because all of the solderable interconnections on the surface of a printed wiring board (PWB) assembly are brought through the reflow heating cycle simultaneously. The article explains four regions of reflow profile, namely, preheat (prebake), preflow (soak), reflow, and cooldown. It concludes with a description on the bare copper assembly process, which is carried out in the inert atmosphere.