Thermal Load Adaptive Surfaces with Microencapsulated Phase Change Materials

The performance stabilization of microelectronic devices and components can benefit from maintaining a constant temperature profile during short term transient loading events. The paper investigates the utility of phase change materials (PCMs) encapsulated as micro-reservoirs within a Si wafer surface for short term thermal energy storage as one possible solution to mitigate temperature transient spikes and provide adaptive surfaces to accommodate thermal loads. Patterned silicon Substrates with 20 micron wide by 10 micron deep holes were prepared with reactive ion etch Surface processing. The holes were filled with a paraffin wax known to undergo melting at a target operating temperature of <60 degrees C. An infrared microscope was used to identify temperature maps for specific regions on the surface under both homogeneous and localized thermal load. For a homogeneous thermal load, the temperature was adjusted over the entire surface sample area using an actively heated and cooled sample stage. A transient and highly localized surface heating was accomplished with a 15 micron diameter Pulsed infrared laser spot. These techniques helped to quantify the thermal response of the composite Si/PCM surfaces during melting of embedded PCM. The composite Si/PCM surfaces demonstrated about 0.1 J cm(-2) areal thermal storage density. Results for the in-situ transient temperature investigations of Si/PCM surfaces are discussed as possible means for maintenance of a constant surface temperature during thermal load transient events.