Microchannel heat sinks (MCHSs) are promising thermal solutions in miniaturized or compact devices. Lightweight aspect has been given huge emphasis in recent years. Metal-based materials are commonly used to fabricate MCHSs due to their high thermal conductivity. Consequently, MCHSs are heavy due to the high density of these materials albeit the small footprint of MCHSs. Polymer-based materials are interesting alternatives. Despite their poor thermal conductivity, lightweight feature attracts the interest of researchers. Heat transfer is a conjugate process of heat conduction and heat convection. Poor heat conductions aspect may be compensated through enhancement of heat convection aspects. Although polymer-based materials have been used in microscale heat transfer studies, their focus was not on their feasibility. The present study aims to evaluate the feasibility of polymer-based MCHSs as thermal solutions. The effect of thermal conductivity of fabrication materials, including polymer-based PDMS, PTFE, PDMS/MWCNT, and metal-based aluminum, on the thermal performance of MCHSs was investigated and compared at various inlet flow rate, fluid thermal conductivity, and microchannel ratio at different constant heat fluxes using three-dimensional CFD approach. Results showed that the thermal performance of MCHSs was greatly affected by the heat conduction aspect in which poor heat conduction limited the thermal performance improvement due to enhanced heat convection aspects. This suggests polymer-based materials have the potential for heat transfer applications through thermal conductivity enhancement. This was confirmed in the further analysis using a recently proposed high thermal conductivity polymer-based graphite/epoxy MCHS and a hybrid-based PDMS/aluminum MCHS. © 2020 Elsevier B.V.