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The rapid advancement of 5G technology necessitates the development of efficient thermal management solutions to handle the increased heat dissipation demands of high-power electronic components. This study presents an optimization strategy for a microchannel cold plate designed for a prototype 5G front-end system, featuring four 22-Watt chips as heat sources. The cold plate, constructed from aluminum, incorporates multiple rectangular flow channels evenly spaced to facilitate uniform heat distribution, with an inlet runner. The primary objective of this study is to optimize the geometry of the flow channels and the coolant mass flow rate at the runner entrance to minimize entropy generation, thereby enhancing the heat dissipation capability of the cold plate while minimizing pressure drop. Given these challenges, this study aims to develop an optimization strategy for cold plate design. This research applies Bayesian Optimization (BO), and Response Surface Methodology (RSM) paired with Genetic Algorithm (GA), and FMINCON (sequential quadratic programming, a built-in optimizer of MATLAB). These methods are utilized to fine-tune the channel dimensions and coolant flow rate, and the data that is used to evaluate entropy of the system is obtained from conjugate heat transfer simulations solved by Ansys Fluent. By using the Gaussian Process model to build response surface and predicting function of entropy generation, the results indicate that BO outperforms RSM paired with GA and FMINCON in terms of entropy reduction with same number of samples. 

Suspended finite ground coplanar waveguide (FG-CPW) interconnects, fabricated with laser-enhanced direct print additive manufacturing (AM), are modeled and characterized in this work. The study focuses on the variation of characteristic impedance and attenuation with design geometry. Acrylonitrile butadiene styrene (ABS) is printed with fused deposition modeling (FDM) to form 10-mm-long suspended ABS bridges and Dupont CB028 is microdispensed to realize conductive traces on the ABS bridges. Femtosecond pulsed laser machining in the ultraviolet range is combined with the AM to create gaps ranging from 8 to 92 μ m in width on either side of a signal line to define the FG-CPW. Three different suspended interconnects are designed, where the total linewidth (signal line plus gaps) is kept constant at 300 μ m for all designs, but the aspect ratio (AR) (signal linewidth divided by total linewidth) is varied. Two multiline thru–reflect–line calibrations are performed to measure each design: one uses printed calibration standards and the other employs a commercial calibration substrate. The attenuation of the interconnects at 30 GHz is 0.28, 0.13, and 0.06 dB/mm for ARs of 0.95, 0.87, and 0.38, respectively. The laser machining of the gaps results in partial substrate removal, which increases the characteristic impedance by approximately 11%. The impact of fabrication tolerances is examined.