Au與Ni為常見的凸塊下金屬層(Under Bump Metallurgy; UBM)材料，，而為了避免基材與銲點間發生界面反應，Ni常被作為擴散阻礙層，而Sn與金屬表面有良好的潤濕性因此常被做銲料，Cu則是常見的基材，因此Au/Sn/Ni/Cu多層結構常見於電子構裝中銲點，本實驗以電鍍方法在Cu基材上分別鍍一層Ni及Sn，最後疊上Au片，形成Au/Sn/Ni/Cu多層結構反應隅，在150、180與200 ºC下進行固/固界面反應，了解介金屬相的演變過程，而為了更加確定Au, Ni, Sn的反應機制及熱力學反應參數，本實驗將會建立在180及240ºC下的Au-Ni-Sn三元合金相平衡圖。在Au-Ni-Sn三元相平衡之實驗結果發現，在兩個溫度中皆發現在Ni3Sn2相及AuSn相之間並不存在連續均勻固溶體，而是Ni3Sn2相對第三元素有著很大的溶解度，並且有一個三元相AuNi2Sn4存在於富Sn區，另外，AuSn4相對Ni也有著較大的溶解度。而在Au/Sn/Ni/Cu多層結構界面反應中，介金屬厚度隨著反應溫度的增加而增厚，但並不影響介金屬的種類，隨著反應時間的增加，富Sn相之 AuSn4、AuSn2會因為相轉變而漸漸變薄且消失；相轉變時體積收縮所造成的孔洞，隨著反應溫度的增加而減少；證實了Ni層確實會阻止Cu-Sn 相 生成，並在Au-Sn相與Ni界面處生成(Ni,Au)3Sn2相。

Au and Ni are widely used in Under Bump Metallurgy. Au is widely used as a anti-oxidation layer, because it has many advantages, such as good anti-oxidation, corrosion resistance and solderability. And Ni is widely used as a diffusion barrier to avoid interfacial reaction between solders and the substrate. Sn is a common material because it has good wetting properties with metal surfaces.And Cu is a substrate. Therefor the Au/Sn/Ni/Cu multilayer structure is a common structure at the solder joint in electronic packaging. So in this study we prepared the Au/Sn/Ni/Cu multilayer structure by depositing a Ni/Sn two-layer structure onto the Cu substrate through electroplating. In order to understand the IMC evolution with various of reaction time at different temperatures,these couples will undergo the solid-solid interfacial reaction at 150, 180 and 200 oC. At the mean time the phase equilibria of Au-Ni-Sn ternary system at 180, 240 oC were experimentally investigated.The result shows that there is no homogenous range from the Ni3Sn2 phase to the AuSn phase, but a large solubility of Au in the Ni3Sn2 phase. There is a ternary compound AuNi2Sn4 in this system, and large solubility of Ni in the AuSn4 phase. In the Au/Sn/Ni/Cu multilayer interfacial reaction shows that the thickness of IMC increased with the increasing temperature ; however, the category of the IMC weren’t change with the different temperature. As the reaction time increased, the Sn-rich phases AuSn4 and AuSn2 gradually became thinner and finally disappeared because the phase transformation. The voids caused by volume shrinkage decreased with the increasing temperature. Ni layer prevented the formation of Cu-Sn IMC, and formed (Ni,Au)3Sn2 phase between Au-Sn IMC /Ni interface.

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