Damage Evolution in Al Wire Bonds Subjected to a Junction Temperature Fluctuation of 30 K
Damage Evolution in Al Wire Bonds Subjected to a Junction Temperature Fluctuation of 30 K
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DOI：
10.1007/s11664-016-4519-0
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发表时间：
2016-07-01
影响因子：
2.1
通讯作者：
Johnson, C. Mark
中科院分区：
文献类型：
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作者：
Agyakwa, Pearl A.;Yang, Li;Johnson, C. Mark
采用无损三维(3D)X射线层析成像方法研究了超声粘结重铝丝在40A℃~70A℃功率循环下的结温小波动。在此条件下，发生了组织的不可逆变形和磨损。观察到的显微组织由界面和晶间裂纹组成，集中在应力强度区，即接近脚跟的位置，并从界面预裂纹处发出。在粘结剂内部也观察到界面空洞。对“第一”键和“缝合”键的降解率进行了比较。一项相关的显微镜研究结合了光学显微镜的观点和X射线断层扫描结果，澄清了观察到的损伤。根据结果对寿命进行了估计，并结合现有的预测进行了讨论。
Ultrasonically bonded heavy Al wires subjected to a small junction temperature fluctuation under power cycling from 40A degrees C to 70A degrees C were investigated using a non-destructive three-dimensional (3-D) x-ray tomography evaluation approach. The occurrence of irreversible deformation of the microstructure and wear-out under such conditions were demonstrated. The observed microstructures consist of interfacial and inter-granular cracks concentrated in zones of stress intensity, i.e., near heels and emanating from interface precracks. Interfacial voids were also observed within the bond interior. Degradation rates of 'first' and 'stitch' bonds are compared and contrasted. A correlative microscopy study combining perspectives from optical microscopy with the x-ray tomography results clarifies the damage observed. An estimation of lifetime is made from the results and discussed in the light of existing predictions.