Advanced packaging technologies are rapidly evolving driven by the quick development of new applications like high-performance computing and artificial intelligence. High-end substrate technology is core support that must concurrently handle the multiple performance requirements, such as high-speed and high-frequency data transmission, power management, ultra-fine-pitch interconnections, and system-level integration. Glass substrates have become a key solution to overcome the limitations of traditional packaging because of their great thermomechanical durability, very low moisture absorption, and exceptional electrical qualities. The structural features and crucial production processes of glass substrates are analyzed, with a special focus on reliability concerns, and the technical opportunities and challenges they faced are summarized.