Mechanical fatigue properties of heavy aluminium wire bonds for power applications
Mechanical fatigue properties of heavy aluminium wire bonds for power applications
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电力应用用重铝线键合的机械疲劳特性
DOI：
10.1109/estc.2008.4684554
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Matthias Petzold
中科院分区：
文献类型：
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作者：
Lutz Merkle;T. Kaden;Marcus Sonner;A. Gademann;J. Turki;C. Dresbach;Matthias Petzold
在这项研究中，提出了一种面向技术的简化铝线键合机械疲劳测试方法以及第一个实验结果。在测试设置中，键合线在室温下受到不同振幅的位移控制负载，并通过实验确定相应的失效周期。环路几何形状在技术上有意义的范围内变化。实验确定的耐久性曲线表明键合几何形状对键合线的寿命有很大影响。除了测试之外，还开发了不同键合线几何形状的三维有限元模型，以便根据等效应变量化失效部位的局部变形情况。用于模拟的整体机械性能是通过未处理的键合线的拉伸测试确定的。就失效循环次数而言的实验结果可以表示为不同粘合环几何形状的跟部等效应变变化的函数。使用常见的双对数耐力图，不同键环几何形状的结果可以通过线性相关性来近似。该结果与可应用 Coffin-Manson 方法来预测铝线键合寿命的预期一致。从这些结果可以得出结论，实验测试方法和应用的模拟模型适用于了解不同粘合环几何形状对失效循环次数的影响。为了更普遍地理解，必须考虑到靠近跟部的机械性能受到疲劳加载之前的粘合过程的影响。初步研究表明，键合线横截面的球形压痕测试提供了一种有用的系统方法来表征这些变化并提取局部材料属性以进一步扩展建模。
In this study, a technology-oriented simplified mechanical fatigue testing approach for aluminium heavy wire bonds as well as first experimental results are presented. In the test setup, bonding wires were displacement-controlled loaded with different amplitudes at room temperature and the corresponding cycles to failure were experimentally determined. Loop geometries were varied in a technological meaningful range. The experimentally determined endurance curves show a strong influence of the bonding geometry on the lifetime of the bonding wires. In addition to testing, a three dimensional finite element model of the different bonding wire geometries was developed in order to quantify the local deformation situation at the failure site in terms of equivalent strain. The global mechanical properties used for the simulations were determined by tensile tests of unprocessed bonding wires. The experimental results in terms of number of cycles to failure could be represented as a function of the change in equivalent strain at the heel for the different bond loop geometries. Using a common double-logarithmic endurance plot, the results for the different bond loop geometries could be approximated by a linear dependency. This result is in accordance with the expectation that a Coffin-Manson approach can be applied to predict the life time of the aluminium wire bonds. From these results, it can be concluded that the experimental testing approach and the applied simulation model is applicable to understand the effect of different bonding loop geometries on the number of cycle to failure. For a more generalized understanding, it has to be taken into consideration that the mechanical properties close to the heel were affected by the bonding process prior to fatigue loading. In form of a preliminary study, it is shown that spherical indentation testing on cross sections of the bonded wires provides a useful methodical approach to characterize these variations and to extract the local material properties for further expanded modelling.