Reliability of Advanced Electronic Packaging for Automotive Systems: An Analysis of PFAS-Free Materials, PCB Pad Cratering, and Encapsulated Printed Circuits

Abstract

The semiconductor industry is experiencing unprecedented growth, driven by rapid expansion in the automotive, aerospace, computing, and wireless communications sectors. This growth places increasing demands on the reliability and sustainability of advanced electronic packaging materials, especially as environmental regulations push for PFAS-free alternatives. Automotive and defense applications require packaging solutions capable of enduring harsh mechanical and environmental stress over extended lifetimes. This dissertation addresses three critical reliability challenges associated with next-generation semiconductor packaging architectures, focusing on Flip-Chip Ball Grid Arrays (FCBGAs) and printed electronics technologies. The first research area develops predictive models for pad-cratering failures in printed circuit board assemblies. By systematically characterizing the mechanical strength of the glass/resin interface through comprehensive fracture mechanics testing, this research has developed an advanced predictive framework capable of forecasting the crack initiation of pad-cratering failures. This model enhances the ability to assess reliability risks in large-scale, high-performance compute PCB systems commonly used in autonomous navigation and data centers. The second area evaluates the mechanical reliability of both PFAS and PFAS-free underfill and thermal interface materials within FCBGA structures, with particular focus on the underfill/substrate and TIM/copper interfaces. Through accelerated aging tests, including high humidity and isothermal storage, coupled with tensile and fracture experiments, the study provides comprehensive insights into the long-term durability of these materials under automotive-grade conditions. Advanced physics-of-failure models, including Arrhenius and Peck models, were employed to develop accelerated life prediction models, providing critical guidance for material selection and design optimization. The third focus investigates the reliability of printed additive circuits and encapsulation materials subjected to thermoforming and environmental aging relevant to automotive applications. This research includes high-temperature operating life (HTOL), humidity, and thermal cycling testing (TCT) to evaluate printed circuit durability. Failure analysis using scanning electron microscopy (SEM) was conducted on electrically conductive adhesives (ECAs) to understand degradation mechanisms. Key process parameters such as curing profiles and surface preparation were identified as critical factors influencing encapsulant adhesion and circuit integrity. The results demonstrate that optimized encapsulation strategies significantly improve peel strength and extend the service life of printed electronics under AEC Grade 3 conditions. Collectively, this work integrates experimental characterization, environmental stress testing, and predictive modeling to advance the understanding of interface mechanics and materials sustainability in next-generation automotive electronics. The findings provide a scientific foundation for the adoption of PFAS-free materials, improved packaging designs and printed circuits applications that meet stringent reliability standards while addressing environmental concerns. This work supports the semiconductor industry’s transition toward greener, more robust solutions essential for the evolving automotive, high-performance compute and aerospace markets.