Performance evaluation of MEMS heat sinks having straight microchannels integrating rectangular sidewall cavities in in-line pattern

Abstract

This work details a silicon-based MEMS heat sink having straight microchannels integrating rectangular sidewall cavities in in-line pattern and employing water for thermal management of microelectronic chips. Simulation-based studies are done for Reynolds number (Re) between 100 and 750 and the model is validated. The thermal resistance (R_th,total) and pumping power (PP_f), of the proposed MEMS heat sink, are lower than that of the conventional MEMS heat sink. At the largest Re, the R_th,total of the proposed MEMS heat sink is only ∼78 % of the R_th,total of the conventional MEMS heat sink and PP_f of the former is only ∼91 % of the latter. Moreover, the Nusselt number (Nu) and Poiseuille number (Po) of the straight microchannel integrating rectangular sidewall cavities is higher and lower than that of the straight microchannel, respectively. With the increase in Re, the Nu of the proposed MEMS heat sink in comparison with that of a conventional MEMS heat sink varied from ∼103 % to ∼147 % while the Po of the former in comparison with the latter varied from ∼81 % to ∼91 %. There exists a threshold for the length of the sidewall cavities below which the performance of the proposed MEMS heat sink is not influenced by the same. Above this threshold, increase in length decreases, for a specific Re, both R_th,total and PP_c as well as increases and decreases the Nu and Po, respectively. Increase in Re leads to reduction of R_th,total and increase of Nu with decrease in the width of the sidewall cavities; both PP_f and Po increase with increase in Re though the influence of width of sidewall cavities on them is negligible. The increase in the number of sidewall cavities decreases R_th,total and PP_f while increasing and decreasing the Nu and Po, respectively. The increase in hydraulic diameter decreases both R_th,total and PP_f while increasing both Nu and Po.