Design. Fabrication, and Test of an Embedded Si-Glass Microchannel Heat Sink for High-power RF Application

The heat dissipation of power amplifier (PA) chips is one of the biggest challenges in the development of miniaturized state of art glass-based high-power RF modules. Glass has excellent electrical properties, but the extremely poor thermal conductivity of it also brings many barriers in the application. Its (quartz glass) thermal conductivity is only 1/93 of that of silicon, so there will be a problem of poor heat dissipation. In recent years, there has been an increasing amount of literature on microfluidic cooling technology and this method was demonstrate as an efficient way in cooling application. In this article, we designed, fabricated, and tested a Si-Glass microchannel heat sink, which took advantage of the high thermal conductivity of silicon to deal with the insufficient thermal conductivity of the glass interposer. Finite element simulation was used to study the thermal property of the Si-Glass heat sink and a multi-parameter optimal method was used to design the geometrical parameters, including the number of flow channels and other geometrical parameters of the heat sink. Then the aforementioned microchannel heat sinks were fabricated using cleanroom fabrication on 4-inch silicon and glass wafers. To complete the thermal test, the Thermal Demonstration Vehicles (TDVs) were fabricated by bonding the sample onto a customized PDMS holder for fluid connections with the flow loop. A programmable power source was used to heat the TDV in a stepwise manner, and a syringe pump was used to supply the liquid to cool the heat sink. Results show that the heat sink can dissipate heat flux greater than 150W/cm ² with substrate temperature lower than 100°C.