Molded underfill process provides many benefits for higher productivity and lower cost over the conventional capillary underfill process. However, the void defects in a molded underfill process could cause pop-corning effect and solder extrusion during the reflow process. This paper presents a highly efficient and accurate hybrid model that can be applied to diagnose the void risk in vacuum molded underfill processes of real flip-chip, package-on-package devices with complex ball arrays and large PCB strips. The model combines multi-zone porous media model, Hele-Shaw model and compressible two-phase computational fluid dynamics model. The model has been well validated in terms of the entrapped void size and its behavior with flow visualization experiments. Also, a set of parametric studies on a FC-POP molded underfill flow process were performed to pre-assess the future node’s molded underfill process. Not only the model provides a better understanding of the physics of void entrapment but also it is proven to be an effective tool for assessing the potential void risk through its application to 10nm flip-chip, package-on-package device manufactured in mass production line.

中文翻译：

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使用新型多孔介质、两相、可压缩流动模拟方法对 FC-POP 模制底部填充工艺中的空隙风险进行参数研究

与传统的毛细管底部填充工艺相比，模制底部填充工艺提供了许多优势，可实现更高的生产率和更低的成本。然而，模制底部填充过程中的空隙缺陷可能会在回流过程中导致爆米花效应和焊料挤出。本文提出了一种高效、准确的混合模型，可用于诊断具有复杂球阵列和大型 PCB 条带的真实倒装芯片、层叠封装器件的真空成型底部填充工艺中的空隙风险。该模型结合了多区多孔介质模型、Hele-Shaw 模型和可压缩两相计算流体动力学模型。该模型在截留空隙大小及其流动可视化实验中的行为方面得到了很好的验证。还，对 FC-POP 模制底部填充流动工艺进行了一组参数研究，以预先评估未来节点的模制底部填充工艺。该模型不仅可以更好地理解空隙截留的物理原理，而且通过将其应用于大规模生产线制造的 10nm 倒装芯片封装器件，它被证明是评估潜在空隙风险的有效工具.