Enhancing the precision of thermal conductivity measurement via transducer patterning in frequency-domain...

The thermal transport properties of materials are critical in the thermal design of electronic devices, particularly as these designs increase in complexity. Modern devices frequently incorporate materials with low thermal conductivity, such as insulators and flexible substances used in wearable technology. Frequency-domain thermoreflectance (FDTR) is a common method for measuring thermal conductivity due to its simplicity and accuracy. However, challenges arise when measuring materials with low thermal conductivity, as the sensitivity of the measurement diminishes. This reduction in sensitivity is primarily due to significant lateral heat transfer within the metal transducer on the sample's surface, complicating the precise determination of thermal conductivity. This study introduces a method to enhance measurement precision by minimizing heat transfer within the transducer. This approach involves selectively patterning the transducer and positioning it near the laser irradiation point to curtail internal heat transfer. This strategy ensures that heat transfer within the sample predominates, thereby augmenting the sensitivity of thermal conductivity measurements. We employed a finite element model to evaluate the effectiveness of this technique and established that transducer patterning notably diminishes the uncertainty in measured thermal conductivities. Validation was achieved by measuring the thermal conductivity of glass [1.216 ± 0.056 W/(m K)]. This measurement is consistent with anticipated values for glass conductivity and demonstrates a reduction in uncertainty to less than one-fourth of that observed in conventional FDTR measurements. Such improvements highlight the method's capability to yield precise thermal conductivity measurements for low-conductivity materials. This advancement addresses the growing imperative for advanced thermal design in modern electronic devices.