Novel and emerging packaging technologies expand the designer's toolbox. Metal coated polymer spheres (MPS) for ball grid array (BGA) assembly is a promising interconnect technology improving reliability, while high thermal conductivity substrates, e.g. AlSiC and AlN, is interesting for enhanced thermal performance. But new tools bring along new challenges in the design phase of innovative packaging solutions. Knowledge of how these tools influence the system characteristics is therefore key; e.g. electrical, mechanical and thermal performance. This study reports on the thermal performance of several novel and more traditional interconnect and substrate technologies. It comprises a relative thermal impact study of individual technologies. The system consists of a power dissipating silicon die assembled onto different substrates with varying interconnect technologies. The study was performed with finite element analysis (FEA) assisted with a compact model and is scheduled for comparison with identical fabricated systems. The results show that it is possible to utilize FEA efficiently on a system scale during the design process with sufficient accuracy. It also reveals that the combination of interconnect and substrate technology should be chosen with care, especially regarding the system's thermal performance, disclosing potential reliability issues and illustrating cost-benefit tradeoffs.