Let us assume an SiP project being started with an inquiry from a customer. Then, chip IO planning, package power planning, and package floorplannig are carried out to make a rough image of the system, followed by bonding design and interposer routability analysis to confirm the rough image being practical. These four major steps, shown in light blue boxes in the figure, are repeated to get to an optimized state. This phase of the design is called the 'feasibility study' (FS). The FS phase is the key of the successful SiP project since it determines the global picture of the SiP, thus the role and interfaces of the involved designers. After the FS phase, detailed design steps will be started in chip side and in package side in parallel, considering manufacturing yield, etc.

　Not many good commercial tools are available for a long time. In the traditional tooling, office tools (Microsoft Excel, PowerPoint, etc) are typically used for chip IO planning, package floor planning, and power planning, which compel designer a tedious work just because the tools are too general purpose. For bonding design and interposer routability analysis, PCB tools are diverted in many cases. The major problem of using PCB tools here is that such tools are mainly intended to help manufacturing design phase, hence cannot provide 'routability analysis' function, without completing the detailed physical design in Gerber level. Furthermore, PCB tools for manufacturing designs are generally too specific for PCB specialists, and cannot provide the communication aid well. Typically, DXF format is used to exchange layout ideas, which lacks some important information, such as netlist.

　GemPackage is tailored just for the SiP FS phase. It supports the chip IO planning, floor planning, and power planning functions, wire/flip-chip bonding designs, and interposer routability analysis. The covered range in the design flow is depicted by green dotted box in the figure. By not implementing the manufacturing design support, the tool stays very simple in operation, which makes the tool and its data as a good communication aid in the team.