本研究主要探討NiCo合金墊層與Sn(Cu)無鉛焊料間的介面反應，首先利用電鍍法將不同Co濃度之NiCo合金層鍍在銅層上，接著將Sn(Cu)焊料與NiCo合金在250 ℃下進行迴焊，最後觀察在介面上生成之介金屬層其生長情形與種類型態並探討NiCo合金組成及焊料Cu濃度對介面反應的影響。
實驗結果發現在當墊層Co濃度從純Ni、Ni-20%Co、Ni-63at%Co到純Co時，介面生成的介金屬依序為單一相的Ni3Sn4，(Ni,Co)Sn2、(Ni,Co)Sn3及CoSn3，且發現Ni-63at%Co墊層的消耗是所有實驗組別裡最快的，這是因為其生成介金屬的結構較鬆散所致。
從Sn(Cu)/NiCo反應結果發現對Ni-20at%Co墊層而言，當焊料Cu濃度高於0.2wt%迴焊300秒後，會有額外的針狀(Ni,Cu)3Sn4相生成在第一相(Ni,Co)Sn2上方並發現在焊料裡添加Cu會增快反應中所生成之(Ni,Co)Sn2的生長速率。對純Co及Ni-63at%Co墊層而言，焊料中Cu的添加及Cu濃度的提升對反應後介金屬種類生成沒有影響，其介面生成的相皆為CoSn3，但是其皆會抑制反應中所生成之CoSn3的生長速率。

In the work, we study soldering reaction between Ni-Co alloy layer and Sn(Cu) Pb-free solders. Different Co concentrations in Ni-Co alloy layer were electroplated on Cu foils. Then, Sn(Cu) solders were reflowed on the Ni-Co alloy layers at 250 ℃ to investigate the growth situation and morphology of IMCs and to discuss the effect of Co concentration and Cu concentration on the reaction between Sn(Cu) and Ni-Co layer.
Experimental results show that when the composition of NiCo alloy are Ni, Ni-20at%Co, Ni-63at%Co and Co, the corresponding IMCs formed at the interface are Ni3Sn4, (Ni,Co)Sn2, (Ni,Co)Sn3 and CoSn3. We also observe that the consumption of Ni-63at%Co alloy is more serious than other NiCo alloys and it is due to the loose structure of IMCs.
In the case of Ni-20at%Co, after 300 seconds reflowing additional needle-like phase (Ni,Cu)3Sn4 was formed right above the continuous (Ni,Co)Sn2 layer when Cu concentration overs 0.2wt% and Cu addition enhance the growth rate of (Ni,Co)Sn2. In the case of Ni-63at%Co and Co, as Cu addition and increasing of Cu concentration are performed only CoSn3 formed at the interface, but these factors restrain the growth rate of CoSn3.

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