Abstract: A soldering apparatus includes a conveyor adapted to carry assembled circuit boards through a soldering chamber. A wave of solder is created in the chamber. The chamber has a curtain at its entrance and a curtain at its exit. Gas distributors are located within the chamber and are able to introduce nitrogen into the chamber in order to create a non-oxidizing atmosphere in the vicinity of the wave. In operation, the wave of solder wets connecting points between the components and the board to form permanent joints on solidification of the solder. The bottom edge of the curtain is of a shape complementary to the front elevation of the assembled circuit boards to be soldered and is arranged such that the circuit boards just pass thereunder without making contact with it.