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On the use of the hot disk thermal constants analyser for measuring the thermal conductivity of thin samples of electrically insulating materials
... Another example of a transient method for measuring the thermal conductivity of thin films is the transient plane source (TPS) method [13,14]. The TPS method for thin films are used on films and adhesives with thicknesses between 50 to 200 m. ...
... The effective thermal conductivity of the sensor layers is determined by performing a reference test ( Fig. 1(a)) and the effective thermal conductivity of both the sensor layers and the thin film can be determined by performing a conventional TPS thin film test ( Fig. 1(b)). From these two tests, the thermal conductivity of the thin film can be calculated using the series model of thermal resistances [7,13,15]. The presence of thermal contact resistance (TCR) between (1) the sensor layers, (2) the sensor and the thin film, (3) the sensor and the background material, and (4) the thin film and the background material makes the method inaccurate because these resistances are added to the thermal resistance of the thin film, leading to a lower thermal conductivity reading than expected [7,16]. ...
... test is a regular TPS test on a thermally conductive background material ( Fig. 1(a)). The measurement time of the reference test should be long enough that Δ ( ) becomes constant, from which the effective thermal conductivity Λ of the insulating layers of the sensor can be calculated using the formula, [13], ...
The conventional transient plane source (TPS) method for thin films is used for films and adhesives with thicknesses between 50 and 200 µm. However, measuring the thermal conductivity of thin films with the conventional TPS method is inaccurate due to thermal contact resistance between the insulating sensor layers, the film and the sensor, and the film and the background material. A new approach to measuring thin films with the TPS is introduced, where the heat flow is constrained to one dimension, and a slab layer made from the same background material is introduced between the thin film and the TPS sensor. This decouples the effects of the thermal contact resistance (TCR) of the sensor to the thermal resistance of the film. The new approach is tested on four different thin films with stainless steel as the background material. The results are compared to guarded heat flow meter measurements. Excellent agreement (< 12% error) between the two methods is achieved, showing that the new method proposed is fast, accurate, and convenient alternative for determining the thermal conductivity of thin films.
... Precise thermal conductivity measurement is one of the key parameters needed in such applications. Thermal properties measurement methods can be classified as: (i) steady state and (ii) transient [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The steady-state methods have the advantage of simplicity of the analysis of the signal and the main disadvantage of long measurement times, whereas transient thermal properties tests are much quicker and more complex to analyze. ...
... The thermal transport properties of a sample can be obtained from analysis of temperature increase of the sensor registered by the sensor, itself, as a function of time. Details of the analytical solution of a transient heat source on a half-space, i.e., the fundamental of TPS method, can be found in [16][17][18][19] and are briefly explained in the next section of this article. ...
... When the nickel element is heated, its temperature and, hence, its electrical resistance increases as a function of time, as follows [19]: ...
... More recently, Boháč et al. developed a model for a circular heat source embedded in a finite (in radial direction) isotropic cylinder with convection at the bounded surface [31]. Related planar geometries, such as that of a strip [11,32,33], square plane with [10] and without [23,[34][35][36] an additional temperature probe, and a bifilar spiral approximated as planar series of nested rings of negligible thickness have also been considered. In the case of the bifilar spiral, it has been considered both analytically [12,[35][36][37] and numerically with additional sensitivity analysis [38][39][40]. ...
... Related planar geometries, such as that of a strip [11,32,33], square plane with [10] and without [23,[34][35][36] an additional temperature probe, and a bifilar spiral approximated as planar series of nested rings of negligible thickness have also been considered. In the case of the bifilar spiral, it has been considered both analytically [12,[35][36][37] and numerically with additional sensitivity analysis [38][39][40]. ...
... There is a possibility to use the initial temperature difference { ΔT i (t) }, cf. Eq. (6), to measure the thermal conductivity of electrically insulating thin sheets [29]. When working with thin-film specimen, they are placed between two high-conducting substrates with a probe in the middle. ...
This experimental method was first proposed in 1991 and is presently being used for determining thermal conductivity, thermal diffusivity, thermal effusivity, and volumetric heat capacity of solids. Under special and well-controlled conditions, it is possible to measure thermal conductivity over approximately six orders of magnitude at temperatures ranging from 25 K up to 1500 K. A feature of this method is the possibility to obtain both the thermal conductivity and thermal diffusivity from one single transient recording and in that way to open up convenient measurements of thermal transport of certain anisotropic materials. A further advantage of using a transient method relates to the possibility to eliminate the influence of the contact resistances always present between the heating element, functioning also as the temperature recorder, and the surface of the substrate under investigation. This review will touch upon the limitations of the method with an estimation of the measuring uncertainty together with a discussion on the influence of the difference between the experimental arrangement and the assumption made in the development of the analytical theory used for analyzing the experimentally recorded data. The method has turned out to be useful not only in measurements of the thermal transport but also for special quality control situations. It is used in both academic institutions and in industrial laboratories and has so far generated some 5000 scientific papers in international journals.
... During the test, a certain temperature rise was generated by the current passing through the probe, and the heat capacity of the probe was negligible. The heat of the probe diffuses to both sides of the sample at the same time, and the average temperature rise of the probe surface was accurately measured according to the resistance change of the metal sheet of the probe (Gustavsson et al., 1997;Mihiretie et al., 2016). The Hot Disk probe is both a heat source and a temperature sensor. ...
The Wugongshan area is rich in medium–low temperature convective geothermal resources, among which there are more than 10 geothermal fields in Wentang, Wanlongshan, Wenjia, Hongjiang, etc. There are few basic geothermal geological studies in the geothermal fields and their peripheral areas; thus far, no systematic research work into the thermophysical parameters has been carried out. In this paper, 85 rock samples were collected from the surface and boreholes covering the strata and magmatic rocks in the study area. The results show that the average radioheat generation rate, the average thermal conductivity, and the average specific heat are 0.24–5.49 (μW/m³), 1.995–4.390 (W/mK), and 1.318–4.829 (MJ/m³K), respectively. The average thermal diffusivity ranges from 1.115 to 1.611 × 10⁻⁶ m²/s. The highest radioheat generation rate is Jurassic granite, and the lowest is quartz vein. The largest thermal conductivity and specific heat is the siliceous quartzite, and the smallest is the quartz vein. The highest thermal diffusivity is Cambrian metamorphic mica schist, and the lowest is siliceous quartzite. The radioactive heat generation rate, thermal conductivity, specific heat, and thermal diffusivity are closely related to the chemical composition, mineral composition, rock fabric, porosity, water content, and temperature and pressure conditions of rocks in the whole area. There is a linear relationship between thermal conductivity (K) and thermal diffusivity (κ), and the correlation equation is K = −0.3144k + 3.2172. Combined with the characteristics of thermophysical parameters, the genetic theory of deep crust heat generation + structural heat accumulation + siliceous quartzite heat conduction + granite heat preservation is preliminarily proposed.
... Using a Hot Disk apparatus and the thin film measurement method [65], the thermal conductivity of the MWCNT -PBI nanofibermats was measured 3.1 W/mK, increased ~650% compared to the value of the pure PBI polymer. This high value of thermal conductivity indicates that these fabrics can be used in many applications where materials of high thermal transport properties are crucial. ...
Abstract
Enhancement of thermal properties of epoxy resins was achieved by incorporation of polybenzimidazole (PBI) fibermats filled with carbon nanomaterials, prepared by the solution electrospinning technique. Different type of carbon nanostructures (carbon nanotubes, graphite flakes, graphene nanoplatelets and carbon black) were compared as fillers in polybenzimidazole fibers. The carbon-PBI-fibermats showed remarkable thermal transport properties and therefore, they were studied as thermal reinforcement material for epoxy composites. Mechanical and thermal properties of produced composites were evaluated and the effectiveness of different types of carbon fillers examined. Results showed that the produced carbon filled fibermats can be used effectively as a thermal reinforcing material in epoxy resins, offering several advantages.
... Two different sample thickness measurements were made in order to eliminate the influence of the thermal contact resistance existing between the contacting surfaces. The transient plane source method [47][48][49] was used to measure the thermal conductivity of the samples, in accordance with ISO 22007-2:2015 [50]. The thermal conductivity data were obtained using the following parameters: room temperature, 10 s measurement time, Kapton disk type, 6 mm measurement depth, 0.0471/K the temperature coefficient of resistance, 3.189 mm sensor radius, 0.012 W power, and temperature drift record. ...
The effectiveness of carbon nanofillers in improving the thermal conductivity of polymer matrix composites has been extensively studied. However, the mechanisms that lead to the effective reinforcement of composite thermal conductivity at the nanoscale remain unclear, and the significant role of filler aspect ratio in determining composite thermal properties needs to be further clarified for various carbon nanofillers. The primary focus of this study was on understanding how important this factor is in determining the thermal properties of polymer matrix composites. The effect of various carbon nanofillers on the thermal conductivity of epoxy matrix composites was studied with special emphasis on the relationship between filler aspect ratio and composite thermal properties. The effect of filler loading on composite thermal conductivity was investigated, and the role of temperature in thermal conductivity improvement was also evaluated. The results indicated that the aspect ratio of carbon nanofillers is of great significance for improving their reinforcing effect on the thermal performance of polymer matrix composite materials. Graphene in any form can improve composite thermal conductivity more effectively than carbon nanotubes and conventional carbon-based nanofillers. A seven-fold increase in composite thermal conductivity has been achieved by incorporating 6% graphene oxide by weight into the polymer matrix. The resultant polymer nanocomposites may be more attractive at elevated temperatures for applications in thermal management, if their thermal stability problems can be effectively addressed. Keywords: Polymer nanocomposites, Thermal properties, Carbon nanofillers, Thermal management, Epoxy matrices, Aspect ratios
... The main advantages of the hot disk technique include: wide thermal conductivity range, from 0.005 W/(mK) to 500 W/(mK); wide range of materialstypes; easy sample preparation; nonmultilative; and more importantly, high accuracy. The papers by Silas Gustafsson are the earliest which introduces and develops the hot disk technique [1][2][3][4][5][6] . ...
This work aims at the improvement of measurement accuracy of thermal conductivity and thermal diffusivity using a hot disk thermal constants analyser. The hot disk technique is based on the transient heating of a double spiral plane sandwiched between two pieces of investigated material. By researching the temperature change in the sensor surface, it is possible to deduce both the thermal conductivity and thermal diffusivity of the surrounding material from one single transient recording, provided the heating power and measuring time are appropriately chosen within the reasonable range defined by the theory and experimental situation. Based on the engineering application requirement for precision and efficacy, a new experimental method has been developed for high-accuracy measurement of thermal conductivity and thermal diffusivity in different experimental conditions. The standardized material Pyroceram 9606, with a thermal conductivity of 4.05 W/(mK), has been investigated and analyzed using the newly developed method. The measurement results show that the precision 5% estimated for thermal conductivity and 4% for thermal diffusivity at or around room temperature and under normal pressure, which indicate that the newly developed method has led to the high-accuracy measurement of thermal conductivity and diffusivity.
... PCB thermal conductivity measurements were performed to establish the accuracy and relevance of the recognized semi-empirical methods of estimating PCB effective thermal conductivity which, incidentally, all exhibit insensitivity to localised effects introduced by variations in copper within the PCB [28,32333435. Measurements were performed using Hot Disk, an instrument that enables averaged or effective thermal conductivity values to be measured at specific points, representative of component locations, using the Transient Plane Source (TPS) method434445. The experimental approach used is described with the aid ofFigure 6, which shows a similar standard test PCB to that presented inFigure 2 , but one used to support an SO- 8 component,Figure 6(a). ...
As the functionality of electronic systems increase, so does the
complexity of printed circuit board (PCB) design, with greater component
packing densities requiring additional internal signal, power and ground
layers to facilitate interconnection. The extra copper content
introduced increases PCB thermal conductivity and heat spreading
capability, which can strongly influence component operating
temperature. Therefore, this experimental study sought to quantify the
impact of PCB construction on component operating temperature and relate
this sensitivity to the package design, PCB effective conductivity and
convective environment. This was achieved by measuring the steady state
thermal performance of four package types (PSO20: heat slug up, PSO20:
heat slug down, LFBGA80 and SBGA352) on up to six different,
single-component thermal test PCBs in the standard natural and forced
convection environments. Test velocities ranged from 0.5 m/s to 5.0 m/s
and all test components contained a thermal test die. Measurements of
junction temperature and component-PCB surface temperature distributions
are both presented for power dissipation levels within the range 0.5 to
6.0 Watts. The study includes the low and high conductivity JEDEC
standard, FR4-based test PCBs and typical application boards. As each
PCB had a different internal structure and effective thermal
conductivity, this study highlights the sensitivity of component
operating temperature to the PCB, provides benchmark data for validating
numerical models, and helps one assess the applicability of standard
junction-to-air thermal resistance (θJA and θ
JMA), as well as both junction-to-board (ΨJB)
and junction-to-top (ΨJT) thermal characterisation
parameters for design purposes on nonstandard PCBs
Sub-millimeter thick phase change material (PCM) composites have been utilized in the thermal management of micro-electronics serving as a novel thermal interfacial material. However, there is a lack of appropriate measuring methods and precise data for the thin-film PCM composites' intrinsic thermal conductivity, as well as the thermal contact resistance (TCR) at interfaces between those thin-films and metal. In this work, the out-of-plane thermal conductivity of thin-film PCM35, which is a paraffin composite showing the melting point of 35 °C, was first gauged through the commercialized transient plane source (TPS) method, followed by a correction process to deduct the TCR between thin films/temperature sensor interfaces. The direct TPS readings were corrected based on the proportional relation between samples’ thickness and inherent thermal resistance. An improved steady-state heat flow apparatus designed for thin-walled samples was then utilized to examine the reliability of the corrected TPS technique, with a relative deviation between them being only ∼7%. In order to test the applicability of the corrected TPS method, the thermal conductivities of thin polytetrafluoroethylene films were also determined. Furthermore, the TCR between thin PCM35 film and thin 1060Al plate was identified by performing the improved steady-state apparatus. The contribution of overheated PCM35 film on fitting the interfacial voids and reducing the TCR were elucidated, which can guide the thermal design with the use of such thin-film PCMs.
The general theory of the transient plane source (TPS) technique is outlined in some details with approximations for the two experimental arrangements that may be referred to as ‘‘hot square’’ and ‘‘hot disk.’’ Experimental arrangements and measurements on two materials, Cecorite 130P and Corning 9606 Pyroceram, using a hot disk configuration, are reported and assessed.