Monolithic Microfluidic Cooling of a Heterogeneous 2.5D FPGA with Low-Profile 3D Printed Manifolds

Heterogeneous integration techniques such as 2.5-D system-in-packages (SiPs) present new challenges that include higher aggregate package power as well as increased thermal crosstalk between different chiplets due to their proximity. This creates the need for advanced cooling solutions uniquely catered to these issues. This work presents the first demonstration of monolithic microfluidic cooling of active 2.5-D ICs to mitigate high-power and thermal crosstalk between chiplets. A 2.5-D FPGA package is used for demonstration purposes. Micropin-fin heat sinks etched directly into the backside of five chiplets in the package are supplied with de-ionized water as coolant through 3-D printed manifolds. This approach helps create a low-form factor cooling solution. Design considerations for the polymer manifold as well as micropin-fin etching are discussed. FPGA core temperature was maintained at approximately 30 °C when dissipating nearly 107 W of power, corresponding to a thermal resistance of 0.074 °C/W, and thermal coupling values as low as 0.010 °C/W. We also demonstrate excellent thermal performance even with elevated inlet temperatures for energy-efficient cooling applications.