Abstract: In infrared soldering of components onto circuit boards, where components such as leaded components are first soldered on one surface of a circuit board and then additional components are soldered on the other surface, it is a problem that the solder joints of the first arrangement of components may melt during the second soldering step. Also, heat is reflected from the apparatus and can raise the temperature of components above a defined maximum. In the invention, a heat sink is provided for absorbing heat from the infrared heat source when no circuit board is present, and for absorbing heat from components already soldered, during the second soldering step. Usually the infrared heat source is above the path of the circuit boards and the heat sink is below the path of, and not in contact with, the circuit boards.