Automatic reflow apparatus with pressure equalization means

An automatic reflow soldering apparatus for soldering a printed circuit board having a plurality of electronic elements mounted thereon to be soldered thereto by transporting the printed circuit board through a heating chamber having an inert gas filled therein, said apparatus comprising:

• a first station arranged on one side of the heating chamber and provided with a first outer opening for enabling the printed circuit board to be transported therethrough into the heating chamber so as to be soldered therein, said first station being further provided with a first inner opening;
• a second station arranged on the opposite side of the heating chamber from said first station and provided with a second outer opening for enabling the soldered printed circuit board to be transported therethrough out of the heating chamber, said second station being further provided with a second inner opening;
• a duct having one end opening and an opposite end opening, said one end opening connected to the first inner opening of the first station and said opposite end opening connected to the second inner opening of the second station, said first inner opening and said one end opening having an area larger than the area of said first outer opening of the first station, and said second inner opening and said opposite end opening having an area larger than the area of said second outer opening of the second station;
• a first sensor arranged in said first station to detect an air flowing condition in said first station and producing a first detection signal;
• a second sensor arranged in said second station to detect an air flowing condition in said second station and producing a second detection signal;
• a first inert gas supplying means actuated in response to the first detection signal to control an amount of the inert gas to be supplied into the duct adjacent to said one end opening thereof;
• and a second inert gas supplying means actuated in response to the second detection signal to control an amount of the inert gas to be supplied into the duct adjacent to the opposite end opening thereof.