With regard to soldering or wetting (coating) with indium, we are often asked to comment on the oxide formation of indium and how to remove it. We are also asked how long will it take for the oxide to reform on the surface.The procedure, below, will help you to better understand indium oxide, its removal, and how to handle it once it has been removed.
Indium is self-passivating.At room temperature, the oxide formation on the surface of the indium will be between 80-100 Angstroms thick. Generally, this amount of oxide is not considered significant to hamper the wetting of the indium to a substrate, especially if a flux is used.Even if a flux is not used, the indium should not have any difficulty forming a joint or coating a surface.
If the application calls for an oxide-free joint and a flux cannot be used, the indium oxide can be easilyremoved following these steps:
- 用异丙醇或丙酮清洗铟，去除表面的有机物。晾干。
- 在 10% HCl 中蚀刻铟 1 分钟，以去除表面氧化物。
- 用去离子水冲洗铟以除去酸。
- 用异丙醇或丙酮冲洗铟，除去水分。
- 用干氮吹干或晾干。
一般来说，刚蚀刻好的铟一暴露在空气中，其表面就会开始形成氧化物，此时氧化层的厚度在 30-40 埃之间，暴露在空气中 2-3 天后，氧化物就会达到 80-100 埃的钝化厚度。
请注意：
在蚀刻过程中，必须注意将铟单元分开，以免它们粘在一起。如果它们粘在一起，很难在不使铟变形的情况下将它们分开。
如果蚀刻后的铟不能立即使用，建议存放在氮气干燥箱中，或者将蚀刻后的铟浸没在干净的丙酮中，以防止暴露在空气中。
