US Patent 7442037 Reflow Furnace

In the first buffering area provided between the inlet of the furnace and the heating chamber, the ambient gas is blown to the printed circuit board from the lower side of the carrier device, while the ambient gas is sucked in the upper side of the carrier device, thus the outside air is prevented from infiltrating and the ambient gas is prevented from flowing out. Furthermore, the flux is prevented from being attached to the printed circuit board, by installing the flux dropping prevention mechanism in the suction port of the ambient gas.