Fabrication of star grooves and rhombus grooves micro heat pipe

Abstract

With the development of miniaturized and high power electronic devices in recent years, electronic heat dissipating apparatus has become important. The concept of micro heat pipe (MHP) was first proposed in 1984 with the application background of electronic cooling. Since that time, numerous theoretical analyses and experimental tests were proposed, and the cross section of the MHP is either rectangular or triangular. But the capillarity of these grooves is low and restricts heat transfer limitation. In this study, star grooves MHP and rhombus grooves MHP were fabricated. Heat transfer performance of the MHP was enhanced due to better capillarity provided by more acute angles and micro gaps. Star grooves MHP and rhombus grooves MHP were fabricated by bulk micro machining on 4 inch (100) silicon wafers. Finally, the MHP structure was bonded by employing eutectic bonding technique. Testing has been conducted to evaluate the performance over a range of working fluid volumes and heat fluxes. We glue the heater on the evaporator section of the heat pipe, infuse cold water through a copper pipe in the condenser section and paste K-type thermocouples on the MHP in the direction of the length. Then we join the thermocouples to a data acquisition system and adopt Fourier's law to calculate effective thermal conductivity. The best thermal conductivities of star grooves MHP and rhombus grooves MHP are 277.9 W m−1K−1 and 289.4 W m−1K−1, respectively.