| 摘要 |
A method and implementing system is provided in which a gas, such as oxygen, is injected on to area of a circuit board to which an electronic component is being mounted. The injected gas causes a formation of a coating or surface alloy layer such as tin-oxide, on the solder joint. The coating causes the solder bead or joint to have a higher surface tension and a higher reflow temperature. In an exemplary double-sided double-pass assembly operation, circuit boards pass through a soldering oven on a first pass to attach components to a first side, and then the board is inverted and passed through the oven on a second pass while components are mounted on the opposite side of the board. During the second pass, a gas injection device is aimed at the component-to-board connection points on the inverted side of the board which were soldered on the first pass. The gas is injected at the point in the soldering reflow oven at which the temperature begins to exceed the solder reflow temperature. The gas injection is effective to cause the formation of a surface layer on the solder bead thereby increasing the surface tension between the circuit board and the mounted component during the second pass reflow.
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