A high-precision apparatus for the characterization of thermal interface materials

Abstract

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 ͑Ϯ0.001 K͒ 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 4.68ϫ 10 −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%.

A Solution-Based Temperature Sensor Using the Organic Compound CuTsPc

“…A proper temperature measurement technique is crucial as temperature is one of the most frequently measured physical quantities in measurement science [2]. Recently, a number of studies on temperature sensors for physical and chemical measurements have been performed with the aim of searching for linear and consistent sensing devices [3,4]. The need for reliable, inexpensive and harmless temperature sensors that can be operated simply is also a concern for many consumers, research and industrial applications [5–9].…”

Electric field effects during nucleate boiling from an artificial nucleation site

“…The absolute uncertainties on the temperature measurement were estimated to be ±0.1 K. An improved uncertainty of ±0.05 K for the temperature differences between the thermocouples within the test sample was made possible by ensuring that the exact same thermocouple wire was used for each sensor. A 2D Monte-Carlo method described by Kempers et al [19] was used to estimate the heat flux and surface temperature uncertainties with a 95% confidence interval. The temperature values were considered as being distributed normally within their uncertainty band, while the thermocouple locations were considered as being distributed uniformly within a ±0.5 mm interval.…”

Modeling and Experimental Characterization of Metal Microtextured Thermal Interface Materials

“…This apparatus is unique in that it takes advantage of small, weUcalibrated thermistors for precise temperature measurements (±0.001 K) using a Lakeshore 370 AC Resistance Bridge. Careful implementation of instrumentation to measure thickness and force also contribute to a low overall uncertainty and a robust error analysis provides uncertainties for all measured and calculated quantities [24].…”

“…Details regarding the uncertainty propagation through the least squares regression are presented in Ref. [24].…”