PURPOSE: To restrain the temperature rise of an IC, and obtain a superior state of solder reflow, by surface treating the rear of an IC provided with a solder bump by using heat reflecting material, and performing reflow by heating using far-infrared ray radiating method.

CONSTITUTION: An IC 12 provided with a solder bump whose rear is subjected to surface treatment by using heat reflecting material 13, e.g. white siver paste, is mounted on a substrate 11, which is mounted on a belt 14. By moving the belt 14 with a belt driving body 15, the IC 12 provided with the solder bump is carried in a reflow furnace. Three far-infrared heaters 21, 22, 24 are arranged in the upper part of the belt type reflow furnace. Two far-infrared heaters 23, 25 are arranged in the lower part of the furnace. Each of the heaters 21-25 is set at an individual specified temperature.