Thermal performance optimization of Si micro flat heat pipes by Box–Behnken design

Si micro heat pipe (MHP) is become an excellent passive cooling device for thermal management of micro electronics packages because of its considerable thermo-mechanical matching and fabrication feasibility with micro machining methods. The structural and operational parameters have nonlinear relationship which effect on thermal performance of MHP. In this experimental study, three different Si MHPs with same dimensions and hydraulic diameter of 120 μm, and various cross-sections are fabricated by micro fabrication methods and tested under different conditions of fluid charge ratios and input powers. To obtain optimal condition among effective input variables of fluid ratio, input power and cross-section’s shape, statistical method of Box–Behnken design (BBD) from response surface method family is used and experiments are performed according to BBD. Comparison between experiments and optimized model, demonstrated BBD method can establish acceptable relationship between effective input/output parameters, without solving the nonlinear and complex equations. Both theoretical and experimental methods confirmed that the trapezoidal MHP associated with rectangular artery which was charged with 40% of its vapor chamber’s volume had the best thermal performance.