Thermo-mechanical reliability of glass substrate and Through Glass Vias (TGV): A comprehensive review

The evolution of electronic packaging technology towards the adoption of glass substrates marks a significant advancement in overcoming the constraints posed by traditional organic materials. This review delves into the thermo-mechanical reliability concerns associated with glass substrates, glass interposers, and Through Glass Vias (TGV), highlighting the inherent fragility of glass and its susceptibility to cracking as key challenges in their widespread application. The unique tunable modulus and closely matched coefficient of thermal expansion (CTE) to silicon, offer promising solutions to stress-related failures, particularly in large-format applications. Despite these advantages, the integration of glass substrates faces obstacles such as stress management, fragility, adhesion issues, and the uniformity of via fills, compounded by the limited availability of long-term reliability data. This paper provides a comprehensive overview of the fabrication processes for glass substrates and TGVs, the impact of design parameters such as via density and aspect ratio on glass substrate reliability, and the mitigation strategies for stress and crack of TGV. Through the examination of Finite Element Analysis (FEA) models and experimental data, we explore the delicate balance between the stress induced by Redistribution Layers (RDL) and the fracture strength of glass, influenced by various design factors. The review also considers the potential of glass substrates in high-density interconnects and advanced packaging architectures, positioning glass as a transformative material in the future of electronic packaging.