由於對環境的保護，有毒的鉛在電子產品中的使用將被禁止，因此尋求一具可靠度佳的球下金屬層(Under Bump Metallurgy, UBM)與無鉛材料搭配是一重要之議題。由於電鍍鎳UBM具有許多優點，因此在此篇論文中，電鍍鎳與無鉛SnAgCu或SnPb材料之界面反應將被仔細的研究探討，另一方面，為便於比較，電鍍銅及無電鍍鎳UBM與SnAgCu或SnPb材料的界面反應亦被研究。對於無鉛SnAgCu材料，無電鍍的阻障效果最佳，電鍍鎳與電鍍銅則差不多。但對於SnPb材料，電鍍鎳則優於電鍍銅。這樣的差異可能是由於界金屬化合物(Intermetallic Compounds, IMC)的反應速率主要控制在錫球與UBM界面處附近參與反應的錫原子濃度。SnAgCu與電鍍鎳或無電鍍鎳(磷)的IMC生成相均為(NiCu)3Sn4，其與錫球之界面並有Ag3Sn相折出。而Sn37Pb與電鍍鎳的IMC生成相亦為(NiCu)3Sn4，但晶粒表面平滑。SnAgCu與電鍍銅的IMC生成相為Cu6Sn5，其與錫球之界面亦有Ag3Sn相析出。

The use of Pb in electronics will be prohibited due to its
toxicity so it is important to find a reliable under bump metallurgy (UBM)
for lead-free solder applications. Electroplating Ni (E-Ni) as a UBM has
potential, and therefore the more detailed investigations of E-Ni UBM for
eutectic SnAgCu and SnPb solders are reported in this paper. In order to
compare the results with E-Ni UBM, electroplating Cu (E-Cu) and
electroless Ni(P) plating [Eless-Ni(P)] UBM for eutectic SnAgCu or SnPb
solders were also studied. For SnAgCu solders, Eless-Ni(P) UBM is the best
on the property of diffusion barrier. However, no obvious difference was
found for E-Ni and E-Cu UBMs. On the other hand, for the SnPb solders,
E-Ni UBM is better than E-Cu UBM on the property of diffusion barrier.
This may be due to the IMC (intermetallic compounds) reaction rate was
controlled by the number of Sn atoms available at the UBM/Solders
interface. Not only the dominant phase (NiCu)3Sn4 was found at the
E-Ni/SnAgCu and Eless-Ni(P)/SnAgCu interface, but also many small
precipitated particles identified to be Ag3Sn phase were found on the surface
of (NiCu)3Sn4 grains. For the E-Ni/SnPb samples, only the Ni3Sn4 phase
was found. For the E-Cu/SnAgCu samples, the dominant phase Cu6Sn5 was
identified and Ag3Sn phase was also found to precipitate on the surface of
the Cu6Sn5 grains.