| 摘要 |
PROBLEM TO BE SOLVED: To keep solderability wettability in satisfactory and stable conditions by stably keeping the inside of a tunnel-like chamber at a low oxygen concentration, and to efficiently remove foreign matters such as flux fume from the inside of the chamber, when jet stream of fused solder is supplied to a printed wiring board, while transferring at an elevation angle in the tunnel-like chamber supplied with N2 gas to solder the board. SOLUTION: To lead an atmosphere in the tunnel-like chamber 4 to the outside, an inlet port 28 is provided upwardly of front stage of a solder bath 8, and an discharge port 32 is provided in the rear stage of a gas supplying port 20 of N2 gas to return the atmosphere. Then, the atmosphere is circulated in the direction of preventing thermal convection in the tunnel-like chamber 4, to suppress an unnecessary atmospheric flow. At the same time, a scavenging device 30 for scavenging and removing the flux fume in the atmosphere is provided in a process of returning, to keep the atmosphere in the tunnel-like chamber clean.
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