A Study on Analyzing and Mitigating Warpage Behavior in Electronic Packages for Enhancing Thermo-Mechanical Reliability

Abstract

The rapid expansion of electronic devices, along with the escalating consumer demands for advanced performance, cost-effectiveness, and compact designs, has given rise to increased design complexities and various assembly and reliability challenges. Warpage is a significant concern that undermines the thermo-mechanical reliability, acting as a barrier to enhancing the overall performance of electronic devices. This paper addresses the prediction and mitigation of warpage issues in Printed Circuit Boards (PCBs) and Flip Chip Ball Grid Arrays (FcBGAs). The goal is to provide solutions that can be applied to improve the reliability of electronic packages.

In Chapter 1, we present an overview of electronic packages extensively utilized in the electronics industry. We discuss the warpage mechanism and underscore its critical impact on electronic packages. Additionally, we introduce a commonly employed solution method for the accurate prediction and effective mitigation of warpage issues.

In Chapter 2, We conducted an analysis of the warpage behavior in a multilayer PCB, comprising two outer circuit layers and two inner circuit layers, considering the influence of copper trace width and pattern. Various copper trace widths and patterns were employed to anticipate the warpage behavior. Our findings indicate that an increase in copper trace width corresponds to an overall decrease in warpage, and the utilization of wavy traces results in lower warpage compared to straight traces. These results offer valuable insights for predicting warpage at the early stages of electronic package development.

In Chapter 3, We investigated the impact of substrate shape on the warpage of FcBGA, a widely used electronic package. As there is a growing demand for high-performance devices and device scaling, thinning the substrate size is crucial. However, reducing the substrate size is associated with increased warpage, posing a significant reliability concern. In our study, we utilized both rectangular and square-shaped substrates, maintaining the same overall area for each package. The rectangular-shaped substrate demonstrated a substantial reduction in warpage, ranging from 37% to 50%. This percentage increase is more pronounced for larger packages, which is advantageous given the high density of electronic components on the package. Our findings propose an effective method to decrease warpage in FcBGA without requiring additional lids or rings, thereby enhancing the feasibility of using thinner substrates. This, in turn, contributes to an improvement in overall reliability and electrical performance of the device.