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In semiconductor manufacturing, because the product quantity is extremely large, so high yield and high reliability are critically important. Low yield will increase cost, and poor reliability will lead to recall; one example is the battery failure of cell phones. For any consumer electronic product in mass production, the concern of reliability is critical, especially the electronic packaging in 3D IC for advanced consumer electronic products, which are widely used now for distance teaching and home office.

In this introductory chapter, we explain what is electronic packaging? Also, what are the science and engineering in it, especially those relate to reliability? If we want to add more functions to hand‐held devices, the operations of memory, logic, and special functions must be increased. At the same time, power as well as battery capacity must be increased too. A larger size battery will squeeze the volume of the rest of the device, which makes the heating problem worse. To remove heat, we must have a temperature gradient. If we consider a temperature difference of 1 °C across a microstructure of 10 μm in diameter, the temperature gradient is 1000 °C/cm, which will induce thermomigration. In turn, Joule heating will enhance electromigration, and thermo‐stress will induce stress‐migration. While these are time‐dependent events, they are of major reliability concern.