Thermographic characterization of a vapor chamber heat spreader with patterned wick structure

• Thermographic method used to characterize vapor chamber heat spreading. • Patterned wick vapor chamber tested under various operating conditions. • Heat flux, charge volume, and inclination angle were systematically varied. • Surface temperatures and radial differences were thermographically measured. • Thermal conductivity of 8400 W/(m·K) attained with low measurement uncertainty. In this study, a noncontact thermographic method was proposed to characterize the heat-spreading performance of a vapor chamber-type heat spreader. A copper vapor chamber charged with water as the working fluid was fabricated; it had external dimensions of 102 mm × 102 mm × 3 mm and incorporated a patterned wick to reduce overall thickness. The proposed method enabled precise evaluation of radial temperature differences by canceling correlated systematic uncertainty factors, allowing effective thermal conductivities to be determined with acceptably low uncertainties. The effects of influential parameters, including heat flux, working fluid charge volume, and inclination angle, were systematically investigated. With increasing heat flux, temperature uniformity improved and the effective thermal conductivity increased, reaching a maximum value of 8400 W/(m·K) ± 670 W/(m·K) at 200 W/cm 2 . As the working fluid charge volume increased, the effective heat-spreading region contracted due to excess liquid accumulation in the condensation region, although enhanced vapor flow in the central region maintained locally high effective thermal conductivity. Under inclined operation, a nonuniform distribution of effective thermal conductivity developed due to vapor buoyancy, liquid hydrostatic pressure, and liquid redistribution. A maximum effective thermal conductivity of 8400 W/(m·K) ± 920 W/(m·K) was recorded at a 45° inclination and 200 W/cm 2 . Overall, the proposed thermographic method proved to be an effective and practical tool for evaluating the heat-spreading characteristics of vapor chambers, enabling both qualitative and quantitative analysis under varying operating conditions.