论文标题
Lengthscale在SN-3AG-0.5CU焊料微观结构的蠕变中的作用
The role of lengthscale in the creep of Sn-3Ag-0.5Cu solder microstructures
论文作者
论文摘要
在恒定的负载拉伸测试和一系列温度下研究了定向固化的SN-3AG-0.5CU wt。％（SAC305）样品，沿载荷方向接近 - <110>方向和不同的微结构长度。蠕变性能通过完善微观结构，即次级树突臂间距（λ2），倍率的金属间间隔（λE）和金属间化合物（λE）和金属间化合物（IMC）大小的减少，表明较长的蠕变生命周期，较低的蠕变率和麦克风的速率（q）的变化（q）的变化（q）的变化（q）固定性（q）的变化（q）样品。主导的蠕变机制是在室温下障碍物控制的位错蠕变，并在升高温度下转移到与晶格相关的空位扩散蠕变（T/T_M> 0.7至0.75）。使用电子反向散射衍射（EBSD）研究了变形机制，并在树突中识别B/-SN之间的应变异质性，而在包含AG3SN和CU6SN5颗粒的Eutectic区域的B/-SN之间进行了识别。重结晶的晶粒的大小是由树突和共晶的间距调节的，但是，对于粗尺度样品（最大的λ2和λE），共结晶区域的重结晶颗粒仅位于IMC旁边，而不是大小生长的IMC。
Creep of directionally solidified Sn-3Ag-0.5Cu wt.% (SAC305) samples with near-<110> orientation along the loading direction and different microstructural lengthscale is investigated under constant load tensile testing and at a range of temperatures. The creep performance improves by refining the microstructure, i.e. the decrease in secondary dendrite arm spacing (λ2), eutectic intermetallic spacing (λe) and intermetallic compound (IMC) size, indicating as a longer creep lifetime, lower creep strain rate, change in activation energy (Q) and increase in ductility and homogeneity in macro- and micro-structural deformation of the samples. The dominating creep mechanism is obstacle-controlled dislocation creep at room temperature and transits to lattice-associated vacancy diffusion creep at elevated temperature (T/T_M > 0.7 to 0.75). The deformation mechanisms are investigated using electron backscatter diffraction (EBSD) and strain heterogeneity is identified between b/-Sn in dendrites and b/-Sn in eutectic regions containing Ag3Sn and Cu6Sn5 particles. The size of the recrystallised grains is modulated by the dendritic and eutectic spacings, however, the recrystalised grains in the eutectic regions for coarse-scaled samples (largest λ2 and λe) is only localised next to IMCs without growth in size.
