建立和提出界面Cu6Sn5化合物在Cu/Sn3.5Ag環形界面和Cu/Bi/Sn結構的Bi/Cu界面的生長模型。我們發現，建構的生長模型能夠很好地預測環形界面處Cu6Sn5化合物生長曲線。此外，環形界面處的Cu6Sn5化合物生長速度比平面界面處的要慢，而導致環形界面處Cu6Sn5化合物生長速度較慢的主要因素是隨著退火時間的增加，Cu6Sn5/solder環形界面的反應區域增加，導致界面Cu6Sn5化合物溶解到solder matrix中的驅動力更大，從而減少了界面Cu6Sn5化合物的生長。 另外，針對Bi/Cu界面處的Cu6Sn5化合物生長，本研究得出以下結論：(1) 當Cu/Sn之間有Bi層存在時，將促進Cu6Sn5的生長；(2) Cu6Sn5在Bi/Cu6Sn5界面處的生長是一個反應控制過程；(3) 在Bi/Cu6Sn5界面處形成的Cu6Sn5化合物層非常均勻，這與Sn和Cu之間形成的典型扇貝狀Cu6Sn5化合物非常不同。我們推測，Bi(或Sn)原子在其晶格結構中鄰近Cu6Sn5生長平面的位置必須被空出，為待填充的Sn位置提供空間。我們發現，Bi中的空位擴散率(Dva)比Sn中的空位擴散率高約三個數量級。這表明，在Cu/Bi/Sn系統中，空位將比在Cu/Sn系統中更快地提供給位於Cu6Sn5生長平面旁邊的待填充Sn位置，在Cu6Sn5/Bi界面處能更快地補充空位，使待填充的Sn和Cu位置更快地填滿Sn和Cu原子，促進了Cu6Sn5化合物的生長。;The growth model of the interfacial Cu6Sn5 compound at the circular Cu/Sn3.5Ag interface and the Bi/Cu interface of the Cu/Bi/Sn structure have been established and proposed. We found that the present developed growth model can predict well the interfacial Cu6Sn5 compound growth curve at the circular-interface. Also, the interfacial Cu6Sn5 compound growth rate at the circular-interface is slower than that at the planar-interface. The major factor for the slower interfacial Cu6Sn5 compound growth rate at the circular-interface attributes to the increase of the interfacial reaction area at the circular Cu6Sn5/solder interface with the annealing time. It causes a larger driving force for the interfacial Cu6Sn5 compound to dissolve into the solder matrix, which reduces the growth of the interfacial Cu6Sn5 compound layer. For the case of interfacial Cu6Sn5 compound growth at Bi/Cu interface, the present results conclude that (1) the Bi insertion layer greatly enhances the Cu6Sn5 formation, (2) the Cu6Sn5 formation is a reaction-controlled process at the Bi/Cu6Sn5 interface, and (3) the Cu6Sn5 compound layer formed at the Bi/Cu6Sn5 interface is very uniform, which is very different from the typical scallop-type Cu6Sn5 compound formed between Sn and Cu. We conclude that the vacancy formation in the Bi (or Sn) lattice structure adjacent to the Cu6Sn5 growth sites plays a key role for the Cu6Sn5 growth at the Bi/Cu6Sn5 and Sn/Cu6Sn5 interface, which renders the to-be-filled Sn sites in Cu6Sn5 compound phase space to be filled with Sn atoms. Thus, the vacancy formation and diffusion in the Bi and Sn lattice adjacent to the Cu6Sn5 growth sites governs the growth kinetics of the Cu6Sn5 layer. The vacancy diffusivity in Bi is much larger than that in Sn by about three orders of magnitude. It results in a quicker vacancy replenishment at the Cu6Sn5/Bi interface, which promotes the Cu6Sn5 growth at the Bi/Cu6Sn5 interface.
