Land grid arrays (LGAs) and ball grid arrays (BGAs) constitute the board-level interconnect technologies for a large number of packaged ICs. These technologies are used in socketing and surface mount (SMT) applications, respectively. The concept of socketable BGA packages, with solder spheres coated with a barrier layer/noble metal coating, was introduced to develop a single package design for processor ICs that are used in both socketing and SMT applications. While this concept has previously been demonstrated, the feasibility of these packages in socketing conditions has not yet been studied. This article assesses the applicability of these packages in socketing by subjecting the packages to thermal aging at a temperature of 120 °C. The change in microstructure with thermal aging along with the consumption of the barrier layer was understood. The joint shear strength evolution with thermal aging and the contamination of the top surface of the spheres was studied by the X-ray photoelectron spectroscopy (XPS) analysis. It was found that the trend for experimental consumption of the barrier layer closely follows the theoretical model predictions. Solid-state solder wicking of the Sn57.6Bi0.4Ag (SBA) solder joint due to creep was confirmed at high homologous temperature for the solder. This, along with grain coarsening over time, led to a decrease in the joint shear strength from 33.5 to 16 MPa. Polymer collars are suggested as a potential solution to prevent the solder wicking and make the package feasible for socketing applications.

中文翻译：

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具有镍金涂层的SAC305球的可插拔BGA封装的热老化可靠性

焊盘栅格阵列（LGA）和球形栅格阵列（BGA）构成了用于大量封装IC的板级互连技术。这些技术分别用于套接字和表面安装（SMT）应用中。引入了可插拔BGA封装的概念，该焊球上涂有阻挡层/贵金属涂层，以开发用于插座和SMT应用中的处理器IC的单一封装设计。尽管先前已经证明了此概念，但尚未研究这些封装在插口条件下的可行性。本文通过使封装在120°C的温度下经受热老化，评估这些封装在插口中的适用性。可以理解随着热老化的微观结构的变化以及阻挡层的消耗。通过X射线光电子能谱（XPS）分析研究了联合剪切强度随热老化的发展以及球体顶表面的污染。发现阻挡层的实验消耗趋势紧密地遵循理论模型的预测。在焊料的高同源温度下，确认了由于蠕变导致的Sn57.6Bi0.4Ag（SBA）焊点的固态焊料芯吸。随着时间的推移，这随着晶粒的粗化，导致接头的剪切强度从33.5 MPa降低到16 MPa。建议使用聚合物套环作为防止焊料芯吸并使包装对于插座应用可行的潜在解决方案。