The book focuses on the design, materials, process, fabrication, failure mechanism, reliability, modeling, and thermal management of chiplets and heterogeneous integration. Both principles and engineering practice have been addressed, with more weight placed on engineering practice. This is achieved by providing in-depth study on a number of major topics such as hybrid bonding, advanced substrates, failure mechanisms, and modeling due to thermal stresses, moisture absorption, impact loading such as drop as well as electric current driven electromigration, and the fundamentals of thermal management. Each topic is treated with in-depth analysis to bridge foundational principles with real-world engineering challenges. This book is an essential resource for researchers, engineers, and students in electrical engineering, mechanical engineering, materials science, and industrial engineering, equipping them with the knowledge to advance innovation in semiconductor packaging and integration.