In-Situ Measurement of Emissivities of Ceramic—Polymer Composite Materials
Abstract:Emissivities of high-dielectric ceramic composites used in microelectronic packaging were measured by a modified hot-filament ASTM method and infrared thermometry; total hemispherical emissivities were measured using the hot-filament method, and effective band emissivities were measured using infrared thermometry. Two ceramics—5m alumina and 2–3m aluminum nitride—were chosen as the base of the substrate. They were blended with poly(vinyl butyral) (PVB) with proper amounts of solvents and cast on a 304-stainless-steel strip used as the heating filament. Emissivity measurements in the temperature range of 380–1000 K were performed using three different sets of experiments. In the first set of experiments, the emissivities of unfired polymer composites were measured in the temperature range of 380–450 K, a temperature at which thermal degradation starts to occur. In the second set, the specimens were heated overnight in a furnace at 673 K for binder burnout, and measurements were conducted on fired composites in the temperature range of 380–1000 K. In the last set, the emissivity of the specimens were measured in situ in the temperature range of 380–1000 K by condensing the degradation products using a liquid-nitrogen cryogenic jacket on-line before the pump line to avoid contamination of the turbomolecular pump. The system pressure was controlled below 5 × 10−5 torr (}6.7 × 10−3 Pa) in all experiments to constrain nonradiative types of heat transfer inside the bell jar.
Document Type: Research Article
Affiliations: Department of Chemical Engineering, University of Missouri, Columbia, Missouri 65211
Publication date: January 1, 1997