The use of reflow flux system for soldering process of SMT electronics results in the concealed residues located underneath of the components, which changes its characteristics upon exposure to humidity. In this paper, the transformation of reflow process-related solder flux residues was investigated under varied humidity and temperature conditions. Evolution of potentially corrosive active components from the residue under high humidity and temperature conditions was investigated for different solder pastes using the acidity indication gel test. Changes in the concealed morphology of the residue were visualized using light optical and scanning electron microscopes, and the observations were correlated to the results from the gel indication test. Quantification of the release of active components from the residue was performed using the extract conductivity measurements. The results show that the evolution of acidic residues from the reflow-soldered pads occurs upon exposure to humidity and temperature due to opening up of the concealed residue, however, temperature alone was found to have no effect on this phenomenon. The hygroscopic nature of the evolved solder flux activators cause the absorption of moisture under humid conditions, accelerating the formation of a conductive electrolyte that provides a potential chance for an undesired corrosion process.

在 SMT 电子设备的焊接过程中使用回流焊剂系统会导致隐藏的残留物位于组件下方，当暴露在潮湿环境中时，其特性会发生变化。在本文中，研究了在不同湿度和温度条件下与回流工艺相关的助焊剂残留物的转变。使用酸度指示凝胶测试研究了不同焊膏在高湿度和高温度条件下残留物中潜在腐蚀性活性成分的演变。使用光学和扫描电子显微镜观察残留物隐藏形态的变化，并将观察结果与凝胶指示测试的结果相关联。使用提取物电导率测量值对残留物中活性成分的释放进行量化。结果表明，在暴露于湿度和温度时，由于隐藏的残留物被打开，回流焊接的焊盘会产生酸性残留物，然而，发现单独的温度对这种现象没有影响。进化出的助焊剂活化剂的吸湿性会导致在潮湿条件下吸收水分，加速导电电解质的形成，这为不希望的腐蚀过程提供了潜在的机会。发现单独的温度对这种现象没有影响。进化出的助焊剂活化剂的吸湿性会导致在潮湿条件下吸收水分，加速导电电解质的形成，这为不希望的腐蚀过程提供了潜在的机会。发现单独的温度对这种现象没有影响。进化出的助焊剂活化剂的吸湿性会导致在潮湿条件下吸收水分，加速导电电解质的形成，这为不希望的腐蚀过程提供了潜在的机会。