Unexpected dual cracks in chip-ceramic substrate interconnect: Unveiling the mechanism behind simultaneous cracking at both the top and bottom of a solder joint

IF 4.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis Pub Date : 2024-10-05 DOI:10.1016/j.engfailanal.2024.108942

Jinhong Liu , Taotao Chen , Qiangqiang Nie , Junfu Liu , Peng He , Kyung-Wook Paik , Shuye Zhang

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引用次数: 0

Abstract

Chip-ceramic interconnect is increasingly vital in high-density IC especially in high-frequency applications, making the reliability of solder joints with underfill material in this case a significant concern. In this study, unexpected simultaneous cracking at both the top and bottom of a solder joint was noted after 500 thermal cycles. Crack 1 propagated along Ti/Pt/Au/SAC305 interface on Si chip side while crack 2 propagated along the solder/IMC interface on AlN HTCC substrate side, which significantly contrasted with prior researches based on FR4 substrate where single cracking typically occurred at one interface. The emergence of two cracks was attributed to tensile stress induced by CTE disparities among different components, including the underfill, which caused two stress interfaces. The FEA results indicated higher stress and strain levels on FR4 substrate compared to AlN, thus facilitating easier crack initiation and more severe crack propagation. The nanoindentation results showed a difference in elastic modulus between the IMC and β-Sn phases, leading to stress concentration during thermal cycling which initiated crack. The increased brittleness of IMC contributed to partial penetration of the crack into the IMC layer during propagation. A strategy to enhance the reliability of the solder joint was also proposed.

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芯片-陶瓷基板互连中的意外双裂纹：揭示焊点顶部和底部同时开裂背后的机理

芯片-陶瓷互连在高密度集成电路（尤其是高频应用）中的重要性与日俱增，在这种情况下，使用底部填充材料的焊点的可靠性成为一个重要问题。在这项研究中，经过 500 次热循环后，焊点的顶部和底部出现了意想不到的同时开裂现象。裂纹 1 沿着硅芯片一侧的 Ti/Pt/Au/SAC305 接口扩展，而裂纹 2 则沿着 AlN HTCC 基板一侧的焊料/IMC 接口扩展，这与之前基于 FR4 基板的研究形成鲜明对比，之前的研究通常只在一个接口上出现单一裂纹。出现两条裂缝的原因是包括底部填充物在内的不同元件之间的 CTE 差异引起的拉应力，从而造成两个应力界面。有限元分析结果表明，与 AlN 相比，FR4 衬底上的应力和应变水平更高，因此更容易产生裂纹，裂纹扩展也更严重。纳米压痕结果表明，IMC 和 β-Sn 相的弹性模量不同，导致热循环期间应力集中，从而引发裂纹。IMC 的脆性增加导致裂纹在扩展过程中部分渗透到 IMC 层。此外，还提出了一种提高焊点可靠性的策略。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Engineering Failure Analysis 工程技术-材料科学：表征与测试

CiteScore

7.70

自引率

20.00%

发文量

956

审稿时长

47 days

期刊介绍： Engineering Failure Analysis publishes research papers describing the analysis of engineering failures and related studies. Papers relating to the structure, properties and behaviour of engineering materials are encouraged, particularly those which also involve the detailed application of materials parameters to problems in engineering structures, components and design. In addition to the area of materials engineering, the interacting fields of mechanical, manufacturing, aeronautical, civil, chemical, corrosion and design engineering are considered relevant. Activity should be directed at analysing engineering failures and carrying out research to help reduce the incidences of failures and to extend the operating horizons of engineering materials. Emphasis is placed on the mechanical properties of materials and their behaviour when influenced by structure, process and environment. Metallic, polymeric, ceramic and natural materials are all included and the application of these materials to real engineering situations should be emphasised. The use of a case-study based approach is also encouraged. Engineering Failure Analysis provides essential reference material and critical feedback into the design process thereby contributing to the prevention of engineering failures in the future. All submissions will be subject to peer review from leading experts in the field.