Thermal Management in Electronics: From Conventional Cooling to Hybrid Innovations

The relentless miniaturization of electronic devices and escalating heat fluxes in data centers, electric vehicles, and aerospace platforms, projected to exceed 1,000 W/cm2 in next-generation chips, have intensified the demand for advanced thermal management. This review systematically surveys electronic cooling progress across a normalized set of metrics: junction-to-coolant thermal resistance, heat flux, pressure drop, and Power Usage Effectiveness (PUE). Conventional strategies including natural and forced-air convection, heat sinks, liquid cold plates, phase-change systems, and thermoelectric coolers are evaluated for their capabilities, limitations, and applicability across heat flux regimes. Emerging approaches such as two-phase microchannel cooling, single-phase and two-phase immersion cooling, jet impingement, spray, and electrohydrodynamic techniques are discussed, with demonstrated performance up to 2,000 W/cm2 and PUE values as low as 1.02. Material innovations including graphene spreaders, SiC microchannel substrates, and nano-enhanced PCMs, alongside computational tools such as topology optimization and ML-augmented CFD, are identified as enablers of step-change performance gains. Cost, carbon footprint, and regulatory considerations, including post-PFAS dielectric fluid requirements, are integrated throughout. Open challenges in two-phase flow instability, lifecycle assessment standardization, adaptive workload-driven control, and long-term hybrid system reliability define the critical research agenda bridging laboratory demonstrations and industrial deployment.