Board level BGA and CSP Underfill – diagnostic methods and the potential of using a tensile test and subsequent optical microscopy

IF 5 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Polymer Testing Pub Date : 2025-05-27 DOI:10.1016/j.polymertesting.2025.108872

Zbyněk Plachý , Anna Pražanová , Attila Géczy , Karel Dušek

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引用次数: 0

Abstract

Reducing the dimensions of Ball Grid Array (BGA) and Chip Scale Package (CSP) components in electronics design and manufacturing presents challenges similar to packages with flip-chips during temperature cycling. Therefore, underfill technology is increasingly used at the board level to enhance the durability of soldered joints in these components and improve the overall reliability of devices. However, a key issue with underfill is the limited quality control options and diagnostic methods available to assess its impact on specific assemblies. This work highlights the application of different diagnostic methods already established in other fields of electrical engineering, emphasizing the advantages of tensile testing combined with three-dimensional optical microscopy. The work results show that although underfill generally enhances the mechanical properties of the assembly, its effects vary significantly between components, so each component needs individual examination. Furthermore, Kernel Density Estimation analysis revealed significant differences in solder joint distribution layout between the components, correlating with their observed mechanical responses. Mechanical stress, Young modulus and toughness were investigated, while the latter appears to be the most suitable for comparing the influence of underfill on assemblies and individual components. The underfilled CSP component showed a 34 % increase in toughness compared to the non-underfilled, while the BGA component showed an increase of 94 %. The CSP component demonstrated a noticeable trend: toughness increased by 20 % from 0 to 2000 temperature cycles but then experienced a decline of 24 % at 3000 temperature cycles. This trend is not apparent for the BGA component. The combination of tensile testing with optical microscopy proves to be an effective method for evaluating the effect of underfill, detecting the weakest parts of the assembly and possibly optimizing its use for various types of BGA and CSP components.

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板级BGA和CSP下填-诊断方法和使用拉伸试验和随后的光学显微镜的潜力

在电子设计和制造中，减小球栅阵列（BGA）和芯片规模封装（CSP）组件的尺寸与在温度循环过程中使用倒装芯片的封装类似。因此，下填技术越来越多地用于板级，以增强这些组件的焊接接头的耐久性，并提高设备的整体可靠性。然而，下填的一个关键问题是有限的质量控制选择和诊断方法，以评估其对特定组件的影响。这项工作强调了在其他电气工程领域已经建立的不同诊断方法的应用，强调了拉伸测试与三维光学显微镜相结合的优势。工作结果表明，虽然下填体总体上提高了组合体的力学性能，但其作用在构件之间差异较大，因此需要对每个构件进行单独检测。此外，核密度估计分析揭示了组件之间焊点分布布局的显着差异，这与观察到的力学响应相关。研究了机械应力、杨氏模量和韧性，而后者似乎最适合于比较下填土对组件和单个组件的影响。与未填充的CSP组分相比，未填充的CSP组分的韧性增加了34%，而BGA组分的韧性增加了94%。CSP组件表现出明显的趋势：从0到2000个温度循环，韧性增加了20%，但在3000个温度循环时，韧性下降了24%。这种趋势在BGA组件中并不明显。拉伸测试与光学显微镜相结合被证明是一种有效的方法来评估下填土的效果，检测装配的最薄弱部分，并可能优化其在各种类型的BGA和CSP组件中的使用。

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来源期刊

Polymer Testing 工程技术-材料科学：表征与测试

CiteScore

10.70

自引率

5.90%

发文量

328

审稿时长

44 days

期刊介绍： Polymer Testing focuses on the testing, analysis and characterization of polymer materials, including both synthetic and natural or biobased polymers. Novel testing methods and the testing of novel polymeric materials in bulk, solution and dispersion is covered. In addition, we welcome the submission of the testing of polymeric materials for a wide range of applications and industrial products as well as nanoscale characterization. The scope includes but is not limited to the following main topics: Novel testing methods and Chemical analysis • mechanical, thermal, electrical, chemical, imaging, spectroscopy, scattering and rheology Physical properties and behaviour of novel polymer systems • nanoscale properties, morphology, transport properties Degradation and recycling of polymeric materials when combined with novel testing or characterization methods • degradation, biodegradation, ageing and fire retardancy Modelling and Simulation work will be only considered when it is linked to new or previously published experimental results.