The Die Embedded and RDL structure on the high density substrate (i-THOP®) for mobile application

The current trend in the electronics industry is one of increased computing performance, combined with a seemingly unending demand for portability and increased miniaturization; this is especially evident in the significant changes to the semiconductor device. To sustain the performance-improvement trend without increasing total cost, the partitioning of single die into a multi-chip architecture is widely studied in industry. These partitioned chips are then integrated into a single system-in-package (SiP). However, partitioning a single die into multiple split die causes two major challenges. The first is that it creates the need for very high density die to die interconnection. This interconnection is needed to provide enough routing density between the multiple die. Based on design studies, it believes that 2μm line and 2μm space is required in the package substrate. The second challenge is created by the increase in the overall die size. After partitioning the single die, each resulting smaller die must have its own I/O circuits, and effectively increases the total die area. This increase is a penalty, as mobile devices have a limited package size. When comparing a conventional package on package (PoP), the SiP requires a higher pin count with a finer pitch connection between the die and the memory. This finer pitch is needed to have enough I/Os, but within a limited package size to support mobile devices. To overcome these challenges, the structure of i-THOP® with POP pad, named “i-THOP® with Die embedded +ReDestribution Layer(RDL) structure”, has been developed. Herein, i-THOP® (integrated Thin film High density Organic Package) is a type of high-density substrate A key aspect to development of Die embedded +RDL is forming the multiple redistribution layers (RDL) over die and the fine pitch via connection. To achieve this, the proper material set was selected based on stress simulations and basic experiments. Regarding the manufacturing process, a conventional printed-circuit board (PCB) production line was used to minimize production cost. This article reports the manufacturing process and characteristics of the structure.