Bridging passive and active cooling: A review of geometric design strategies for hybrid electronic packaging systems

Abstract

The continuous escalation of power density in electronic packages, driven by transistor miniaturization and artificial intelligence (AI) accelerators, has rendered single-mode cooling inadequate and established hybrid thermal management as a design necessity. While previous reviews have examined the heat transfer mechanisms and overall performance of passive, active, and hybrid cooling techniques, a systematic analysis that explicitly links geometric design parameters to thermal performance across all three categories within a single comparative framework remains absent. This review establishes such a framework by analyzing structure and performance relationships across a hierarchy of cooling technologies. The influence of fin geometry, wick architecture, and base thickness on thermal resistance in heat sinks, heat pipes, and vapor chambers is analyzed through fin efficiency and capillary-balance formulations for passive cooling. The effects of channel configuration on heat transfer in forced convection, liquid cooling, and immersion cooling systems are examined for active cooling, with surface modification strategies addressed where geometric and wettability parameters govern phase-change behavior. Hybrid architectures integrating multiple heat-transfer mechanisms are then systematically evaluated, with emphasis on how passive-passive and active-passive geometric combinations enable cooling performance exceeding single-mode limits. This review further addresses the long-term reliability under thermal cycling and orientation sensitivity in direct conjunction with geometric performance analysis, which are aspects rarely discussed in prior literature. Design guidelines are derived for selecting geometric configurations suited to next-generation electronic packaging through this structure-focused framework.