In the present study, a previous solder joint reliability study is revisited. The results of drop tests conducted on Ball Grid Array (BGA) electronic components mounted onto printed circuit boards with copper terminals coated with Organic Solder Preserver (OSP) submitted to aging heat treatments are studied, focusing on the possibility of identifying switches in failure mechanisms with increasing time-to-failure. The results are discussed based on microstructural characteristics of lead-free solders and its influence on crack propagation. The failure mechanisms encountered are discussed, as well as the explanations given by other authors in the literature for the seemingly contradictory results obtained. The wide range of competing failure mechanisms activated during drop tests and microstructural features such as morphology of phases encountered and the presence of voids contribute significantly to the dispersion of the data, and should be taken under consideration whenever reliability studies based on drop tests are performed. Although this feature is not usually considered in reliability tests, Weibull analyses are efficient to identify the occurrence of competing or switching mechanisms, and even at what point of the life expectance each one is likely to take over.

在本研究中，重新审视了先前的焊点可靠性研究。对安装在印刷电路板上的球栅阵列 (BGA) 电子元件进行跌落测试的结果进行了研究，该元件涂有有机焊料保护剂 (OSP) 并经过老化热处理，重点是识别故障机制中的开关的可能性增加故障时间。讨论结果基于无铅焊料的微观结构特征及其对裂纹扩展的影响。讨论了遇到的故障机制，以及其他作者在文献中对看似矛盾的结果给出的解释。在跌落测试期间激活的各种竞争失效机制和微观结构特征（例如遇到的相的形态和空隙的存在）对数据的分散有很大影响，并且在进行基于跌落测试的可靠性研究时都应予以考虑。尽管在可靠性测试中通常不考虑此功能，但威布尔分析可有效识别竞争或切换机制的发生，甚至每个机制可能会在预期寿命的哪个点接管。