The Flow of Dense Suspensions in Manufacturing Processes

本研究的目的是提高对毛细管流动过程的基本理解，这是电子系统制造中的关键步骤，并通过开发基于软件的流动过程工具有效地提供这些过程基础。 流动过程出现在直接芯片附着封装电子产品的制造中。 这里，焊料凸块阵列提供芯片和基板之间的I/O互连。该工艺的目标是使悬浮在环氧树脂中的二氧化硅颗粒的混合物“悬浮”材料快速流入由芯片、基板和焊料凸点表面形成的通道中。 本文将对稠密悬浮液在小流道中的毛细流动进行实验研究。 混合物-空气界面的运动将被跟踪，并与许多参数相关，包括芯片到衬底的间隔（10~100微米）;混合物流变学;润湿表面（化学不均匀性和图案化表面拓扑结构都是电子应用的典型特征）;以及焊料凸块几何图案。 将对商业悬浮液材料和模型悬浮液进行流变学测量。 流程建模将在两个不同的层次上进行：（1）了解基本机制;（2）开发成本效益计算策略，以便在流程工具中实施。

The objective of this research is to improve the fundamental understanding of a capillary flow process, that is a key step in the manufacture of electronic systems, and the effective delivery of these process fundamentals through the development of software based flow process tool. The flow process arises in the manufacture of direct-chip-attachment packaged electronics. Here a solder bump array provides the I/O interconnection between a chip and substrate. The process goal is to rapidly flow an "underfill" material, which is a mixture of silica particles suspended in an epoxy, into the passage formed by the chip, substrate and solder bump surfaces. A laboratory study on the capillary flow of dense suspensions in small flow passages will be conducted. Motion of the mixture-air interface will be tracked and correlated with a number of parameters including the chip-to-substrate standoff (10~100 microns); the mixture rheology; the wetting surfaces (both chemical inhomogeneity and patterned surface topology are typical of the electronics application); and, solder bump geometric pattern. Rheological measurements will be conducted for both commercial underfill materials and model suspensions. Flow modeling will be conducted at two distinct levels: (1) to understand the underlying mechanisms; and, (2) to develop cost-effective calculation strategies for implementation in the flow process tool.