Abstract
The use of Sn-3mass%Ag-0.5mass%Cu lead-free solder (SAC305) has become common. Since SAC305 has a higher content of tin than conventional tin–lead eutectic solder, erosion of the Fe plating layer used in the solder iron tip and the point soldering machine nozzle frequently occurs. In this study, to prolong the life of the Fe plating layer, the applicability of composite plating in which a carbon-type filler is compounded with Fe was studied. Graphite and a multi-walled carbon nanotube (MWCNT) were used as filler materials in the composite plating layer. For both Fe-graphite and Fe-MWCNT composite plating layers, solderability testing and erosion-resistance testing were carried out. In the solderability test, although the spread rates of SAC305 to both Fe-graphite and Fe-MWCNT plating layers slightly decreased compared to the Fe plating layer, SAC305 solder was not repelled against both plating layers. In the erosion-resistance test, the Fe-MWCNT composite plating layer performed the best with the least erosion depth. The erosion depth of the Fe-graphite composite plating layer and the Fe plating layer were 10 and 100 times larger than that of the Fe-MWCNT composite plating layer, respectively. It was confirmed that the diffusion of Fe into molten SAC305 could be greatly reduced due to the composing carbon filler in Fe.
Highlights
Due to the toxicity of lead to the environment and our health, the EU has enforced directive RoHS and prohibited the use of eutectic Sn–Pb solder (Sn-37mass%Pb; Sn-37Pb)
When stainless steel is used for the flow soldering bath with SAC305, the damage of stainless steel due to erosion occurs quickly in the bath [1,2,3,4,5,6]
The cause is that SAC305 contains a greater percentage of Sn, which reacts with other metals and has a higher melting point by around 30 K compared to Sn-37Pb
Summary
Due to the toxicity of lead to the environment and our health, the EU has enforced directive RoHS and prohibited the use of eutectic Sn–Pb solder (Sn-37mass%Pb; Sn-37Pb). It has become common to use Sn-3mass%Ag-0.5mass%Cu lead-free solder (SAC305) instead of Sn-37Pb. As SAC305 has become more common, the erosion of metals in the soldering machine has become a problem. The cause is that SAC305 contains a greater percentage of Sn, which reacts with other metals and has a higher melting point by around 30 K compared to Sn-37Pb. In the case of SAC305, the erosion of the flow soldering bath has been confirmed by previous studies, and countermeasures are taken by surface treatments such as nitriding treatment on the surface of the bath [4,5]. In such damaged parts, currently, the only countermeasure is to replace it with a new one
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
