Reflow soldering is a process in which a
solder paste (a sticky mixture of powdered
solder and
flux) is used to temporarily attach one or several electrical components to their
contact pads, after which the entire assembly is subjected to controlled heat, which melts the solder, permanently connecting the joint. Heating may be accomplished by passing the assembly through a
reflow oven or under an
infrared lamp or by soldering individual joints with a hot air pencil.