Using Metallic Coatings to Enhance Thermal Contact Conductance of Electronic Packages
TL;DR: In this paper, a thermomechanical model for coated contacts has been developed and shown to be quite accurate for a common electronics packaging problem: heat transfer across an aluminum joint.
Abstract: Recently a new thermomechanical model for coated contacts has been developed and shown to be quite accurate. After a brief overview of the theory, this paper concentrates on illustrating the utility of the new model by applying it to a common electronics packaging problem: heat transfer across an aluminum joint. Several soft metallic coatings are considered, and the thermomechanical model is used to predict the improvement in the contact conductance over that for a bare aluminum-to-aluminum joint. For each coating material, heat transfer performance is presented as a function of the coating thickness, the surface roughness, and the applied pressure. Finally, a parameter is proposed that allows candidate coating materials to be ranked.
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TL;DR: In this article, the authors review and highlight over 40 years of research on solutions for steady-state and transient thermal constriction and spreading resistances, and thermomechanical models for contact, gap and joint resistances of joints formed by conforming rough surfaces, nonconforming smooth surfaces, and non-conforming rough surface.
Abstract: The Keynote Paper reviews and highlights over 40 years of research on solutions for steady-state and transient thermal constriction and spreading resistances, and thermomechanical models for contact, gap and joint resistances of joints formed by conforming rough surfaces, nonconforming smooth surfaces, and nonconforming rough surfaces. Microgap and macrogap thermal resistance and conductance models are reviewed, and important relations and correlation equations are presented. Contact microhardness, determined by Vickers indenters, are correlated and incorporated into the contact model for conforming rough surfaces. Microhardness parameters are correlated with Brinell hardness values. Elastoplastic contact models for joints formed by smooth sphere-smooth flat and conforming rough surfaces are presented. A simple thermomechanical model for microgaps occupied by oil, grease, grease filled with solid particles, and phase change materials such as paraffins is reviewed, and good agreement with recently published data is noted.
277 citations
Cites background from "Using Metallic Coatings to Enhance ..."
...It was shown [38], [44] that the dimensionless contact conductance is given by...
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...approximate correlation equation [38], [44]:...
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...For details of the application of the mechanical and thermal models to some problems from the microelectronics industry, the reader should consult [38], [44]....
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...The effect of thin, soft, isotropic high thermal conductivity coatings such as a silver layer on a Ni 200 substrate was studied analytically and experimentally [38], [44]....
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...The effect of oxides [34] and thin metallic layers on TCR were examined experimentally [34], [38], [44], [54], [68], [72] and analytically [44], [52], [54], [57], [58], [61]....
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TL;DR: In this article, the experimental values of the thermal boundary resistance occurring at interfaces between two solids at sub-ambient temperatures are reviewed, and new data are presented in the temperature range from 4 K to 300 K for the thermal resistance between different metals (Cu, stainless steel), interlayered by various cryogenic bonding agents (Apiezon-N, Cryocon grease, In and InGa), or mechanically connected (dry) contacts.
Abstract: The experimental values of the thermal boundary resistance occurring at interfaces between two solids at sub-ambient temperatures are reviewed. New data are presented in the temperature range from 4 K to 300 K for the thermal resistance between different metals (Cu, stainless steel), interlayered by various cryogenic bonding agents (Apiezon-N, Cryocon grease, In and InGa), or mechanically connected (dry) contacts. Depending on the contact materials, the thermal conductance varies between and at room temperature, and decreases approximately linearly by one order of magnitude between 200 K and 20 K. Our experimental data agree well with the data reported in the literature for the temperature range below 4 K and measurements near room temperature.
127 citations
TL;DR: In this article, the authors provide a qualitative and quantitative assessment of the most promising switchable insulation technologies for building envelopes and identify the opportunities for further research in each of the technologies.
55 citations
TL;DR: In this paper, the authors evaluate possible coatings and determine those most suitable for enhancing contact conductance based upon predictions using existing theories for thermal contact conductances of coated junctions.
Abstract: The reliability of standard electronic modules may be improved by decreasing overall module temperature. This may be accomplished by enhancing the thermal contact conductance at the interface between the module frame guide rib and the card rail to which the module is clamped. The surface irregularities resulting from the machining or extruding of the components cause the true contact area to be much less than the apparent contact area, increasing the contact resistance. Some metallic coatings deform easily under load and increase the contact area and associated conductance. This investigation evaluates possible coatings and determines those most suitable for enhancing contact conductance based upon predictions using existing theories for thermal contact conductance of coated junctions.
45 citations
TL;DR: In this article, a fractal prediction model is developed for the thermal contact conductance between two rough surfaces based on the rough surface being described by three-dimensional Weierstrass and Mandelbrot fractal function and assuming that there are three kinds of asperity deformation modes: elastic, elastoplastic and fully plastic.
Abstract: The thermal contact conductance problem is an important issue in studying the heat transfer of engineering surfaces, which has been widely studied since last few decades, and for predicting which many theoretical models have been established. However, the models which have been existed are lack of objectivity due to that they are mostly studied based on the statistical methodology characterization for rough surfaces and simple partition for the deformation formats of contact asperity. In this paper, a fractal prediction model is developed for the thermal contact conductance between two rough surfaces based on the rough surface being described by three-dimensional Weierstrass and Mandelbrot fractal function and assuming that there are three kinds of asperity deformation modes: elastic, elastoplastic and fully plastic. Influences of contact load and contact area as well as fractal parameters and material properties on the thermal contact conductance are investigated by using the presented model. The investigation results show that the thermal contact conductance increases with the increasing of the contact load and contact area. The larger the fractal dimension, or the smaller the fractal roughness, the larger the thermal contact conductance is. The thermal contact conductance increases with decreasing the ratio of Young’s elastic modulus to the microhardness. The results obtained indicate that the proposed model can effectively predict the thermal contact conductance at the interface, which provide certain reference to the further study on the issue of heat transfer between contact surfaces.
37 citations
References
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23 Jun 1981
TL;DR: In this article, the theoretical relationship for determining contact, gap, and joint conductances for conforming rough surfaces for first loading is developed, where the dimensionless conductances are functions of the relative contact pressure, surface parameters, conductivity ratio, and a fluid parameter which depends upon several gas and surface characteristics.
Abstract: The theoretical relationships for determining contact, gap, and joint conductances are developed for conforming rough surfaces for first loading. The dimensionless conductances are functions of the relative contact pressure, surface parameters, conductivity ratio, and a fluid parameter which depends upon several gas and surface characteristics. The proposed conductance correlations are supported quantitatively
143 citations
TL;DR: In this paper, the results of an experimental investigation of the thermal resistance of contacts with coatings and linings of soft metals (silver, copper) at compressive stresses of up to 56 ·105 N/m2 over a temperature range of 250 −600°C were presented.
Abstract: The article presents the results of an experimental investigation of the thermal resistance of contacts with coatings and linings of soft metals (silver, copper) at compressive stresses of up to 56 ·105 N/m2 over a temperature range of 250–600°C. The specimens were made of different kinds of stainless steel or of a molybdenum alloy.
28 citations
07 Jun 1982
27 citations
13 Sep 1965
18 citations