在現今實際BGA或Flip Chip銲點中，銲料的兩端分別為UBM或表面處理層。故一個實際銲點結構可視為一metal/solder/metal的三明治結構。而Ni/solder/Cu的結構又是微電子銲點中很常見的一種組合。故本研究主要的目的是要探討在此類的結構中，Cu/solder及Ni/solder間的界面反應是否會互相影響。亦即在Ni/solder/Cu銲點之兩界面間是否會有交互作用？然而在本實驗室過去的研究中曾經證實[TSA2]，在Flip Chip銲點中兩界面之交互作用在迴銲完後就已發生。但由於在迴銲的過程中，兩端會有部分的金屬溶入銲料當中，使整個系統變的過於複雜。故在本研究中，我們使用電鍍的方式，製造出Flip Chip尺寸的Ni/Sn/Cu擴散偶。利用其不需經過複雜的迴銲過程的優點，來探討在單純200 ℃的固態反應下，Cu、Ni在銲料間交互作用的情況。並將之與作為對照組的單一Ni/Sn、Cu/Sn界面反應結果比較，觀察其三者間的差異。 在單純200 ℃的固態反應15分鐘的時間。由金相觀察的結果發現，Ni、Cu兩端界面皆生成Cu-Sn介金屬，其組成由EPMA分析得知為Cu6Sn5的介金屬。故我們可以得知，在此Ni/Sn/Cu擴散偶中，經過短時間的固態反應後，Cu端Cu原子已擴散至Ni端影響其界面介金屬的生成。亦即此時Cu、Ni間的交互作用已經產生。經過長時間的反應，Ni、Cu兩端生成的介金屬種類並沒有變化，在Ni端為(Cu1-xNix)6Sn5，Cu端則為不含Ni的Cu6Sn5及Cu3Sn。但在介金屬的形態上，卻與一般固/固反應界面生成物的形態較為不同，會呈現較大的高低起伏。在反應動力學方面，在Ni/Sn/Cu系統中，經過長時間的固態反應後，當對端有Cu層存在時，使Ni界面生成以Cu為主的(Cu1-x Nix)6Sn5，故會抑致Ni端Ni的消耗。相反的當對端有Ni層存在時，使兩端界面皆生成以Cu為主的介金屬Cu6Sn5及Cu3Sn，故會加速Cu端Cu的消耗。 In a real solder joint, the solder is always sandwiches between two metals. And the Ni/solder/Cu combination is one of the most common one in microelectronics devices. The objective of this study is to investigate whether the cross-interaction will occur between the interface of solder/Cu and Ni/solder. In fact, it is reported that the two interfaces of Ni/solder/Cu joint would interact after reflow. Therefore, it is known that the dissolved metal results in the system become complex. As the result, the Ni/Sn/Cu diffusion couples were prepared by electroplating in this study to investigate the cross-interaction of Cu and Ni in solder joint only in solid/solid reaction. Experiments were carried out at 200 ℃ for 15 minutes. It was found that Cu6Sn5 compound existed at both Ni/Sn and Cu/Sn interface. Basing on the result, we can say that the cross-interaction of Ni and Cu in a solder joint occurred very quickly at 200 ℃thermal aging. After long term thermal aging, the reaction product didn’t change at both Ni/Sn and Cu/Sn interface. There is(Cu1-xNix)6Sn5 at Ni/Sn interface and Cu6Sn5、Cu3Sn at Sn/Cu interface.Beside it, we found that the microstructure of these reaction product is different from Sn/Cu and Sn/Ni diffusion couple. In other words, the morphology of IMC is largger variation than Sn/Cu and Sn/Ni diffusion couple. In thermodynamic kinetics, it has been show that the formation of of (Cu1-xNix)6Sn5 over the Ni layer can reduce the Ni consumption rate. At the same time, the Cu consumption rate of the opposite side was accelerated.
