A Review of Two-Phase Forced Cooling in Three-Dimensional Stacked Electronics: Technology Integration

Abstract

Three-dimensional (3D) stacked electronics present significant advantages from an electrical design perspective, ranging from shorter interconnect lengths to enabling heterogeneous integration. However, multitier stacking exacerbates an already difficult thermal problem. Localized hotspots within individual tiers can provide an additional challenge when the high heat flux region is buried within the stack. Numerous investigations have been launched in the previous decade seeking to develop cooling solutions that can be integrated within the 3D stack, allowing the cooling to scale with the number of tiers in the system. Two-phase cooling is of particular interest, because the associated reduced flow rates may allow reduction in pumping power, and the saturated temperature condition of the coolant may offer enhanced device temperature uniformity. This paper presents a review of the advances in two-phase forced cooling in the past decade, with a focus on the challenges of integrating the technology in high heat flux 3D systems. A holistic approach is applied, considering not only the thermal performance of standalone cooling strategies but also coolant selection, fluidic routing, packaging, and system reliability. Finally, a cohesive approach to thermal design of an evaporative cooling based heat sink developed by the authors is presented, taking into account all of the integration considerations discussed previously. The thermal design seeks to achieve the dissipation of very large (in excess of 500 W/cm2) background heat fluxes over a large 1 cm × 1 cm chip area, as well as extreme (in excess of 2 kW/cm2) hotspot heat fluxes over small 200 μm × 200 μm areas, employing a hybrid design strategy that combines a micropin–fin heat sink for background cooling as well as localized, ultrathin microgaps for hotspot cooling.

Inertial manipulation of bubbles in rectangular microfluidic channels

“…The comparison between the two sets of results is summarized in Table 2 with isopropanol as the carrier fluid and Table 3 with ethanol as the carrier fluid. In the tables, Ȳ and Z are calculated using eqn (1) and (2). At Re ≤ 1.29, the predicted bubble position from the simulations does not correspond to the experimental values.…”

“…1 A large number of studies have investigated the performance of these heat sinks for electronic cooling. [2][3][4][5] In the field of reactor engineering, variants of reactors including trickle-bed, 6 fluidized bed, 7 and bubble column reactors 8 rely on multiphase flows to enhance mass transport which requires a thorough understanding of their complex physics. Moreover, in most electrochemical sys-tems, gaseous products evolve at the interface of the electrodes and the electrolyte, including important processes such as water electrolysis, 9 chlor-alkali 10 and aluminum production.…”

Flow regimes and convective heat transfer of refrigerant flow boiling in ultra-small clearance microgaps

“…The absence of these regimes is expected to be linked to the ultra-small clearance of the geometry investigated, which confines bubble growth to an extent where only one flow regime, vapor plumes, was observed before dryout. Several studies [2,4,[6][7]24] have shown a similar phenomenon where the transition to annular convective flow boiling occurs at lower vapor qualities as the microgap height decreases due to increased bubble confinement.…”

“…Device features including micro pin fins, air trenches, ports and plenums were etched in silicon using Bosch process with high precision and accuracy. The microfabrication process flow for these devices was documented by Green et al [24].…”

Experimental Study on the Evaporation and Condensation Heat Transfer Characteristics of a Vapor Chamber

“…Vapor-liquid phase change has always been of great interest in a wide range of technical applications, such as electronic cooling [1,2], chemical processes [3,4], space thermal control [5,6], microfluidic preparation [7,8], biomedical engineering [9,10], etc. As a typical technical application, a vapor chamber is recognized as one of the most effective ways to achieve uniform heat dissipation in a confined space due to its good temperature uniformity, flexible system compatibility, and high thermal transport capacity [11,12].…”