Reduction of the Oxide Layer on a Lead-Free Solder Material by Hydrogen Radicals

Abstract

Recently, there has been a demand for lead (Pb)-free solders for use in the electronics industry. However, this poses a challenge in their practical applications because the main component of typical Pb-free solders is tin (Sn) and therefore these solders are prone to oxidize easily. In this paper, we propose a novel technique for the reduction of oxides of the powder which is the raw material of Pb-free solders, and which has Sn as its main component using NH 3 decomposed species generated using a hot-wire (HW) method. It is confirmed that the tin oxide can be reduced by this treatment and the re-oxidation of the solder is also suppressed. Moreover, it is also confirmed that this treatment is effective in controlling the particle size of the Pb-free solder. Further, we clarify that the activation energy of the reduction of the tin oxide is almost zero by this process is almost zero, which indicates that the temperature dependence of the reduction is low.

Evaluation of hydrogen radical treatment for indium surface oxide removal and analysis of re-oxidation behavior

“…19,20) Previous studies on hydrogen radical treatment have been conducted to evaluate the effects of metal surface oxide removal, and it was found to be highly effective for various metals including tin-based solders. [21][22][23][24][25] It was also found that tin-based solders have slower reoxidation rates when treated with hydrogen radicals. [26][27][28] Therefore, hydrogen radical treatment is expected to be a suitable surface oxide removal method for indium, which solves previously discussed problems.…”