An improved steady-state method for measuring the thermal contact resistance and bulk thermal conductivity of thin-walled materials having a sub-millimeter thickness

Abstract

Thin-walled materials, such as alloys, polymers, and glasses, with a thickness between 0.1 and 1 mm have been widely utilized in the encapsulation structures of electronic devices (e.g., the shells of laptops, cellphones, and cameras). The thermal contact resistance (TCR) and bulk thermal conductivity of these thin-walled materials are the key parameters for thermal design of electronic devices. In order to measure the TCR of thin-walled materials having a sub-millimeter thickness, an improved steady-state method was proposed in this work, which is based on the ASTM D5470 standard with the improvement being relied on in situ detection on the sample thickness variations. Such an improved apparatus was designed and constructed, which is equipped with a high-precision laser displacement sensor for measuring the sample thickness. Numerical simulations were performed to verify the heat dissipation from the insulated rods and the experimental uncertainties were analyzed. The measured bulk thermal conductivity was compared with those obtained by traditional steady-state, laser flash and transient plane source methods. The overall TCR of thin-walled stainless steel (SS304) was determined to be of the order of 10-4 m2·K/W, which was in good agreement with that of bulk SS304 samples having similar surface roughness (TCR = 3.13 × 10−4 m2·K/W).