Co-packaged electronics with microfluidics for direct-to-package cooling

Power semiconductors operating under high heat fluxes and elevated temperatures rely on liquid-cooled heat sinks with substantial coolant volumes. Recent advancements in direct-to-chip (D2C) cooling techniques have shown enhanced thermal performance, reduced energy consumption, compact form factor, and minimized coolant usage. However, integrating microchannels onto semiconductor substrates poses significant fabrication challenges. Hence, we propose a direct-to-package (D2P) cooling approach that embeds microchannels within the package substrate, thereby bypassing the need for Thermal Interface Materials and complex fabrication processes. This D2P approach achieves high heat flux dissipation (up to  ~ 625 W cm^-2) tested in this study, while consuming a fraction of the coolant volume ( ~ 2  - 4 mL). The co-packaged architecture demonstrates  ~ 6  - 7 × lower junction temperatures and thermal resistances than ambient-air cooling and  ~ 2  - 3 × lower than heat sink cooling. A very high coefficient of performance is achieved, with an effective global Nusselt number  > 10. This work establishes D2P liquid cooling integration as a scalable and energy-efficient approach for high-power systems.