With the Moore’s Law slowing down, chiplet based packaging solution has been increasingly appealing for advanced computing applications. With more than a decade of development and evolution, the CoWoS-S technology has become one of the most popular 2.5D integration packaging solutions, given its superior advantages on high bandwidth signal transmissions, low latency connections, smooth logic die to high bandwidth memory (HBM) communications, and the most importantly, its numerous high volume manufacturing successes.However, challenges lie in front of designers who are obligated to deliver a high-density redistribution layer (RDL) silicon interposer design with the pursuit of reduced design cycle time and satisfactory power integrity (PI) and signal integrity (SI) performances. As the pioneer in the design tool industry, Cadence has been putting continuous efforts in developing new design methodologies and efficient design tools to empower the 2.5 package design. In this article, we will present a systematic design flow with the aid of Cadence tools that enable a more vigorous interposer design process. In addition, methods to achieve desired PI performance for core area with high current demands and SI performance for connections between the logic die and memories under given crosstalk and capacitive parasitic effects will be illustrated. The criticality of advanced Cadence tools and design methodology in solving the challenges related to the latest CoWoS-S technology will hence be shown.