Development and Testing of a Planar, Silicon Mini-Capillary Pumped Loop

A planar, silicon mini capillary pumped loop (CPL) was designed, built, and tested using recent MEMS technology to provide integral cooling and temperature control for electronics. This design featured three silicon fusion bonded wafers incorporating an evaporator, condenser, liquid line and vapor line, all of which were dry plasma etched. Grooves were etched in the condenser and evaporator to provide passive capillary pumping. The finished device was bonded to an external reservoir via a through port hole and was filled with a working fluid of water. The evaporator was bonded directly to an insulated gate bipolar transistor (IGBT) with a calorimeter expoxied above the condenser to control the temperature and monitor heat removal by the CPL. From testing it was determined that the 1cm x 0.8 cm evaporator provides 15 degrees of constant cooling when the IGBT was run at 3 W and that the system performs like a thermal diode turning on or off depending on the reservoir temperature. Work is in progress to understand the dynamics observed in the CPL as well as increase the CPL’s performance to its full potential.