Kempers R, Kolodner P, Lyons A, Robinson A J
Department of Mechanical and Manufacturing Engineering, Trinity College Dublin, Dublin 2, Ireland.
Rev Sci Instrum. 2009 Sep;80(9):095111. doi: 10.1063/1.3193715.
An apparatus has been designed and constructed to characterize thermal interface materials with unprecedented precision and sensitivity. The design of the apparatus is based upon a popular implementation of ASTM D5470 where well-characterized meter bars are used to extrapolate surface temperatures and measure heat flux through the sample under test. Measurements of thermal resistance, effective thermal conductivity, and electrical resistance can be made simultaneously as functions of pressure or sample thickness. This apparatus is unique in that it takes advantage of small, well-calibrated thermistors for precise temperature measurements (+/-0.001 K) and incorporates simultaneous measurement of electrical resistance of the sample. By employing precision thermometry, low heater powers and minimal temperature gradients are maintained through the meter bars, thereby reducing uncertainties due to heat leakage and changes in meter-bar thermal conductivity. Careful implementation of instrumentation to measure thickness and force also contributes to a low overall uncertainty. Finally, a robust error analysis provides uncertainties for all measured and calculated quantities. Baseline tests were performed to demonstrate the sensitivity and precision of the apparatus by measuring the contact resistance of the meter bars in contact with each other as representative low specific thermal resistance cases. A minimum specific thermal resistance of 4.68x10(-6) m(2) K/W was measured with an uncertainty of 2.7% using a heat transfer rate of 16.8 W. Additionally, example measurements performed on a commercially available graphite thermal interface material demonstrate the relationship between thermal and electrical contact resistance. These measurements further demonstrate repeatability in measured effective thermal conductivity of approximately 1%.
已设计并制造出一种装置，用于以前所未有的精度和灵敏度对热界面材料进行表征。该装置的设计基于ASTM D5470的一种常见实施方案，其中使用经过充分表征的量热棒来推断表面温度并测量通过被测样品的热通量。热阻、有效热导率和电阻的测量可以作为压力或样品厚度的函数同时进行。该装置的独特之处在于，它利用小型、校准良好的热敏电阻进行精确的温度测量（±0.001 K），并结合对样品电阻的同时测量。通过采用精密测温法，量热棒中的加热器功率较低，温度梯度最小，从而减少了由于热泄漏和量热棒热导率变化引起的不确定性。精心设计测量厚度和力的仪器也有助于降低总体不确定性。最后，通过强大的误差分析得出所有测量和计算量的不确定性。进行了基线测试，通过测量相互接触的量热棒的接触电阻，作为代表性的低比热阻情况，来证明该装置的灵敏度和精度。在热传递速率为16.8 W的情况下，测得的最小比热阻为4.68×10⁻⁶ m²·K/W，不确定度为2.7%。此外，对一种市售石墨热界面材料进行的示例测量表明了热接触电阻和电接触电阻之间的关系。这些测量进一步证明了测得的有效热导率的重复性约为1%。
