| 摘要 |
PURPOSE:To curtail the nitrogen gas quantity for preventing oxidation, injected into a reflow furnace. CONSTITUTION:Nitrogen gas is injected into a reflow furnace 11 from a nitrogen gas injecting part 17, and by a heater 12 and a stirring machine 13, a nitrogen gas atmosphere of a high temperature is formed in the furnace. A work W is carried into the atmosphere by a conveyor 14 and reflow soldering is executed. In a work carrying-in part 15 of the reflow furnace 11, and infrared-ray lamp 31 and an infrared-ray sensor 32 for detecting a work are provided. In a gas injection duct line 24 connected to the nitrogen gas injecting part 17, a solenoid valve 33 is provided. This solenoid valve 33 is switched and operated through an amplifier 34 by a work existence/advance signal from the sensor 32, and executes increase/decrease control of the nitrogen gas flow rate. While the sensor 32 is detecting the work W within a prescribed time, a state that the solenoid valve 33 is fully opened is held by a signal from the sensor 32, and a large quantity of nitrogen gas is injected into the furnace. When a state that there is no work W is continued, the solenoid valve 33 constricts the gas injection duct line 24, and limits the injection flow rate of nitrogen gas injected into the furnace. |
