Flow Boiling in Microgap Coolers for 3D Integrated Circuits, Year 3

The proposed embedded cooling approach, which facilitates integration of coolant channels within the chip stack or laser head, offers high heat flux cooling, reduces heat exchanger size, minimizes thermal resistance between the heat source and sink (thus reducing radiator size), and negates gravity effects on the two-phase coolant flow. The proposed effort will assess the thermal capabilities of two-phase cooling in chip stacks, validate FY16 orientation independence results in a variable gravity environment, and quantify system-level space, weight, and power advantages. The previous FY16 effort demonstrated stable flow boiling in 180μm channels, such as those expected between adjacent dies within a 3D chip stack, while dissipating as much as 68W of heat from a 1.6 cm2 thermal test chip. In addition, the FY16 effort established the feasibility of gravity-insensitive two-phase flow performance in 180μm channels and transported 35W of heat using only 1.2W of pumping power. A specialized test facility was fabricated for this effort. For FY17, a key deliverable will be design and testing of a simulated, space-qualifiable , 3D chip stack with an embedded microgap cooler. This will be followed by testing in a centrifuge at the nearby Army Research Laboratory in Adelphi, Maryland. More »