Development of a frequency-domain thermoreflectance instrument for thermal characterization of diamond-based composites

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

High-performance, high-reliability microelectronic devices are essential for space applications. Thermal packaging such as metal-diamond composite is required for regulating heat accumulation, promoting an extended lifetime of the devices. Still, the heat conduction in the composite microstructure which is crucial to the successful development of composite thermal packaging is not fully understood. Hence,
a suitable thermal measurement technique is required. In this work, a frequency-domain thermoreflectance (FDTR) system is developed specifically for the thermal characterization of the metal-diamond composites.
The FDTR system is designed and built based on a pump-probe configuration employing continuous-wave diode lasers as pump and probe, reducing complexity and promoting cost-effective setup. The system employs low modulation frequencies allowing for measurement of bulk samples with thickness ranging from tens of microns to a few millimeters. A discussion on the setup challenges and important preparations affecting the measurements is also included. Measurement processes and data analysis are described. Materials with known thermal conductivity covering an order of magnitude are measured as a demonstration. The results show that measured thermal conductivities are in line with the literature values.
Finally, the thermal characterization of diamond-based composite materials, e.g., copper-diamond and silver-diamond composites, is demonstrated. An approach for the measurement and the method for extracting thermal properties are presented. The results show that the thermal conductivity of the metal-diamond composite and the thermal boundary conductance of the metal cladding and the metal transducer can be obtained from a single measurement. Moreover, the capability for thermal property mapping is demonstrated. Overall, the FDTR system is successfully built with the capability for the thermal characterization of the diamond-based composites as well as thermal property mapping.
Date of Award24 Jun 2021
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorMartin H H Kuball (Supervisor) & James W Pomeroy (Supervisor)

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