A study of deformation mechanism during nanoindentation creep in tin-based solder balls
A study of deformation mechanism during nanoindentation creep in tin-based solder balls
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DOI：
10.1115/1.2429712
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发表时间：
2007-03
影响因子：
1.6
通讯作者：
T. Shibutani;Qiang Yu;M. Shiratori
中科院分区：
文献类型：
--
作者：
T. Shibutani;Qiang Yu;M. Shiratori
随着器件的小型化和集成化，锡基合金的蠕变行为在微观尺度上变得越来越重要。本文研究了钎料合金在纳米压痕试验中的蠕变行为。对锡基焊料球进行了纳米压痕蠕变试验。得到的结果概括如下：（i）幂律蠕变的应力指数估计可以从硬度的演变评估。在高应变速率范围内，早期获得的这些值与体相对应。(ii)在纳米压痕蠕变试验中，应力松弛后应力敏感性降低。三个焊球中的饱和值为1。(iii)压痕表面形貌由三部分组成：初始压痕、幂律蠕变和颗粒表面。这表明，从幂律蠕变到扩散蠕变的过渡发生。(iv)有限元分析表明，在尖端附近出现应力和应变集中。随着压痕的进行，应变场保持自相似。(v)在纳米压痕试验中，由于扩散流动，尖端以下的三轴应力梯度相对加速蠕变应变速率。
As the shrinkage and integration of devices, the creep behavior of tin-based alloys becomes important with microscales. In this paper, the behavior of creep deformation in solder alloys during a nanoindentation test was examined. Nanoindentation creep test was carried out for tin-based solder balls. Obtained results summarized as follows: (i) The stress exponent for power-law creep estimated can be evaluated from the evolution of hardness. These values obtained in the early stage corresponds with that of bulk within the range of high strain rate. (ii) The stress sensitivity decreases after stress relaxation in nanoindentation creep tests. The saturated value is 1 in three solder balls. (iii) The morphology of indented surface consists of three parts: initial indentation, power-law creep, and granular surface. It suggests that the transition from power-law creep to diffusion creep takes place. (iv) Finite element method analysis reveals stress and strain concentration appears in the vicinity of the tip. Strain field remains self-similar as the indentation proceeds. (v) The gradient of triaxial stresses below the tip in a nanoindentation test accelerates the creep strain rate due to the diffusive flow, relatively.