In this paper, the nickel–phosphorus (Ni–P) diffusion barrier layer between Sn–4Ag–0.5Cu solder alloyudand copper-printed circuit board was developed. The electroless plating technique was used to developudNi–P diffusion barrier layer with different percentage of phosphorus content, which are 1–5 wt% (low),ud5–8 wt% (medium) and above 8 wt% (high). The results reveal that the high phosphorus content inudnickel layer acts as a good diffusion barrier for Sn–4Ag–0.5Cu since it can suppress the intermetallicudcompound formation. This is because in higher phosphorus content, the grain boundaries were found toudbe eliminated. Hence, resulted in thinner intermetallic compound thickness.
展开▼
