(Dr. Sam Shelton, advisor)

"Cogeneration Dedicated to Heating and Cooling"

Abstract

Flip Chip on Board (FCOB) is one of the most quickly growing segments in advanced electronic packaging.  Current assembly processes are not capable of providing the high throughputs needed for integrated Surface Mount Technology (SMT) processing.  A new high throughput process using no-flow underfill materials has been developed that has the potential to significantly increase flip chip assembly throughput.  Previous research has demonstrated the feasibility and reliability of the high throughput process as necessary for FCOB assemblies.

The goal of this research was to integrate the high throughput flip chip process on commercial flip chip packages and to assess underfill compatibility with different substrate designs.  The first part focused on application of no-flow underfills with a commercial package utilizing the classical high lead on eutectic solder interconnects.  This involved extensive experimentation into underfill promotion of solder wetting and package void minimization to provide acceptable component performance and reliability.  The second part focused on analysis of substrate features and their effects on void capture in no-flow underfills using the high throughput flip chip process.  This involved a thorough statistical analysis of main and interaction effects among a selection of factors, and provided significant knowledge on appropriate substrate design and assembly process specifications that minimize underfill void capture.  In essence, the research helped expand the applicability of the high throughput process into the commercial packaging arena, and provided insight into appropriate solder wetting and underfill voiding relative to controllable design and processing factors.