The purpose of this study is to investigate the effect of the adhesive force and density ratio using lattice Boltzmann method (LBM) during underfill process.,To deal with complex flow in underfill process, a framework is proposed to improve the lattice Boltzmann equation. The fluid flows with different density ratio and bump arrangement in underfill are simulated by the incorporated Carnahan–Starling (CS) equation of state (EOS). The numerical study conducted by finite volume method (FVM) and experimental results are also presented in each case at the different filling percentage for verification and validation purpose.,The numerical result is compared well with those acquired experimentally. Small discrepancy is detected in their flow profile. It was found that the adhesive force between fluid and solid was affected by the density ratio of the fluids and solder bump configuration. LBM has shown better adhesive force effect phenomenon on underfill process compared to FVM. LBM also demonstrated as a better tool to study the fluid flow in the underfill process.,This study provides a basis and insights into the impact of adhesive force and density ratio to the underfill process that will be advancing the future design of flip chip package. This study also provides superior guidelines, and the knowledge of how adhesive force is affected by flip chip package structure.,This study proposes the method to predict the adhesive force and density ratio effect for underfill flow in flip chip package. In addition, the proposed method has a good performance in representing the adhesive force during the underfill simulation for its natural physical basic. This study develops understanding of flow problems to attain high reliability for electronic assemblies.

中文翻译：

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基于格子Boltzmann方法的粘合力对底部填充工艺的影响

本研究的目的是使用格子玻尔兹曼方法(LBM)研究底部填充过程中粘附力和密度比的影响。,为了处理底部填充过程中的复杂流动,提出了一种改进格子玻尔兹曼方程的框架。底部填充中具有不同密度比和凸点排列的流体流动通过合并的 Carnahan-Starling (CS) 状态方程 (EOS) 进行模拟。有限体积法 (FVM) 进行的数值研究和实验结果也在每种情况下以不同的填充百分比呈现，以进行验证和验证。数值结果与实验获得的结果进行了很好的比较。在它们的流动剖面中检测到小的差异。发现流体和固体之间的粘附力受流体的密度比和焊料凸点配置的影响。与 FVM 相比，LBM 在底部填充工艺中表现出更好的粘合力效应现象。LBM 还被证明是研究底部填充过程中流体流动的更好工具。本研究为粘合力和密度比对底部填充过程的影响提供了基础和见解，这将推动倒装芯片封装的未来设计。本研究还提供了卓越的指导方针，以及关于倒装芯片封装结构如何影响粘合力的知识。本研究提出了预测倒装芯片封装中底部填充流动的粘合力和密度比效应的方法。此外，所提出的方法以其自然物理基础在底部填充模拟过程中表现出良好的粘合力。这项研究加深了对流动问题的理解，以实现电子组件的高可靠性。