As systems-in-package (SIP) concept begins to look attractive for RF Power amplifier manufacturers due to its miniaturization and cost advantages, it poses several manufacturing challenges brought by its added complexity in assembly processes and new concepts of integration. Consequently, process variations in the production line such as bonding critical wires are not only the hidden hurdles that can transform an RF SIP device into a yield disaster due to enormous yield fluctuations but also from the foundry process variations of the die wafer that contains most of its active circuits. To account for these variations, designing for high manufacturing yield is as important as designing for good electrical performance. The over-all electrical performance of a SIP device should be robust enough to absorb drifts within the extreme tolerances of its raw components and should be less sensitive to process variations. This paper presents an up-front method on how to identify critical processes and other factors such as die related variations that proved to be major causes of performance drift resulting to drastic fluctuations in the manufacturing yield. Statistical analysis provided insights and justifications on laboratory results leading to optimum yield and design centering.