| 摘要 |
PROBLEM TO BE SOLVED: To reduce a temperature unevenness on a board, to decrease a difference between a liquidus temperature of a using solder and a highest temperature part of the board and to allow to be connectable by moving the board in a reflow furnace by a combination of a linear motion parallel to a conveying passage for conveying the board and a motion except the linear motion. SOLUTION: One independent movable shaft 3 and a board conveying base 1 having a turntable 2 are provided on a board conveying passage in a reflow passage, and the board mounting the shaft at a center is rotated about 1 r.p.m. in a horizontal plane (plane parallel to the conveying passage). A Pb-free solder alloy near an Sn-Ag two-component eutectic line of Sn-Ag-Bi alloy is used, when a Bi amount is set to 15% (liquidus temperature of the solder: 204 deg.C), a temperature of the board highest temperature part needs to be 220 deg.C or above, but it may be 215 deg.C so that the temperature can be lowered, and hence discoloring or deforming of the board can be prevented. A content of the Bi for causing curing of the solder is lowered, and hence a stress relaxation of the solder is easily facilitated.
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