2022 年 63 巻 8 号 p. 1112-1119
In accordance with the EU RoHS Directive, the use of Sn–3 mass%Ag–0.5 mass%Cu lead-free solder (SAC305) has become the standard in the manufacturing of electronics. Since SAC305 contains more tin than the conventional tin-lead eutectic solder, erosion of the Fe plating frequently occurs on a hand soldering iron tip and a point soldering machine nozzle. In this study, to extend the life of the Fe plating layer, we investigated the applicability of a composite plating in which Fe is combined with the boron nitride (BN) compounds. We used BN particles as the bulk material, and boron nitride nanotubes (BNNT) as a nanomaterial, to fabricate the regarded composite materials. A solderability test and an erosion resistance test were conducted on the composite plating layer, made of both Fe-BN particles and Fe-BNNTs composites. In the solderability test, the spreading factor of SAC305 on the Fe-BN particle and on the Fe-BNNT composite platings were about the same as, or a little decreased compared to, that of the bare Fe plating. The SAC305 solder was not repelled by either composite plating. In the erosion resistance test, the Fe-BNNT composite plating performed the best, and had the lowest erosion depth. The erosion depths of the Fe-BN particle composite plating and the Fe plating ranged from about 6 to 24 times greater, respectively, than those of the Fe-BNNT composite plating layer, confirming that, in a nanomaterial BNNT-base, composite diffusion of Fe into SAC 305 can be suppressed.
