Thermal Contact Conductance of Metal/Polymer Joints: An Analytical and Experimental Investigation

Abstract

The heat ow across a metal/polymer interface is a very important problem in many modern engineering applications. A thermal joint conductance model that employs the surface mechanics of a contact interface in conjunction with an existing elastic thermal contact conductance model was developed. In developing the model, an elastic contact hardness term was derived to predict the actual contact area of a metal/polymer interface under loading. The model predicts a microscopic resistance region where the interface resistance is dominant and a bulk resistance region where the thermal conductivity of the polymer is dominant. An experimental apparatus was fabricated, and a successful experimental program was conducted. New experimental data were gathered on different polymeric specimens over a pressure range of 138-2758 kPa (20-400 psi). The experimental data were compared to the proposed thermal joint conductance model. It was found that the proposed model predicted the data quite well. The data followed the predicted trends for both the microscopic and bulk resistance regions. Nomenclature A a= apparent area of contact, m 2 A r = real area of contact, m 2 a c = contact radius, m a 0 = Hertzian contact radius, m c = half-width of plane contact area, melastic modulus of polymer, Pa E s = elastic modulus of substrate, Pa H c = contact microhardness, Pa H e = Mikic elastic hardness (E 0 = p 2)£ m, Pa H ep = polymer elastic hardness, Pa h bulk = thermal bulk conductance, W/m 2 K h c = thermal contact conductance, W/m 2 K h e = dimensionless elastic conductance h j = thermal joint conductance, W/m 2 K h j exp = experimentally calculated joint conductance, W/m 2 K h micro = thermal microscopic conductance, W/m 2 K J .t / = creep compliance k ux = thermal conductivity of ux meter, W/m K k p = thermal conductivity of polymer, W/m K k s = harmonic mean thermal conductivity, W/m K L = load, N m ab = mean absolute asperity slope, rad n = number of contact spots per unit area of apparent contact, m ¡2 P = apparent pressure, Pa P=H c = dimensionless plastic contact pressure P=H e = dimensionless elastic contact pressure P m = mean pressure at interface, Pa Q = heat rate, W q = heat ux through ux meter, W/m 2 R b = bulk thermal resistance, K/W R g;1 = gap resistance at interface 1, K/W R g;2 = gap resistance at interface 2, K/W R j = joint resistance, K/W R micro = microscopic thermal resistance, K/W R t;c = contact resistance, K/W R 1 = thermal resistance for upper interface, K/W R 2 = thermal resistance for lower interface, K/W T c = temperature of specimen, K T sl = temperature of lower interface of specimen, K T su = temperature of upper interface of specimen, K T 1 = temperature at surface 1, K T 2 = temperature at surface 2, K t = elastic layer (polymer) thickness, m t f = polymer thickness after loading, m t 0 = polymer thickness before loading, m t ¤ = critical polymer thickness, m Y = separation distance between contacting surfaces, m Y .t / = relaxation modulus " p = strain on polymer in the vertical directioņ = dimensionle...

Effective Thermophysical Properties of Thermal Interface Materials: Part I — Definitions and Models

“…Experimental data from Marotta and Fletcher [6] and Fuller and Marotta [9] were compared to the joint conductance model and good agreement was found. The most recent experimental and analytical studies on TIMs were conducted by Marotta et al [12].…”

“…The most comprehensive analytical study based on polymer experimental data was conducted by Fuller and Marotta [9]. They obtained an analytical model for predicting thermal joint resistance between metals and thermoplastic or elastomeric polymers by assuming optically flat surfaces at uniform pressures in vacuum.…”

“…Copyright © 2003 by ASME [3] Al 2024-T4 Silicone elastomers, Fluocarbon elastomer, Nitrile elastomer Fletcher et al [4] Al 2024-T4 Ethylene vinyl acetate copolymers, Ethyl vinyl acetate copolymer, Polyethylene homopolymer Ochterbeck et al [5] Al 6061-T6 Polyamide in combinations with foil, paraffin, diamonds, copper Marotta and Fletcher [6] Al 6061-T6 Polyethylene, PVC, Polypropylene, Teflon, Delrin, Nylon, Polycarbonate, Phenolic Parihar and Wright [7] SS 304 Silicone rubber (elastomer) Mirmira et al [8] Al 6061-T6 Elastomeric gaskets (Cho-Therm, T-pli, Grafoil) Fuller and Marotta [9] Al 6061, SS Delrin, Teflon, Polycarbonate, PVC Marotta et al [12] Al 6061 eGraf, Furon (graphite-based) mer thickness at zero load. Therefore, the joint conductance was defined as:…”

An Integrated Mechanical–Thermal Predictive Model of Thermal Contact Conductance

“…According to Fuller and Marotta [18], the surface geometry chosen is the major difference among contact conductance models. Surface roughness description plays an important role in the mechanical and thermal modeling.…”

Evaluation of heat transfer coefficient between polymer and cavity wall for improving cooling and crystallinity results in injection molding simulation

“…Sridhar [7] modeled the development of thermal contact resistance during injection molding process by using an air gap conductivity model and observed a significant increase in thermal contact resistance. Fuller [8] built an analytical thermal conduction model to predict thermal conduction of metal/polymer joints. Masse [9] calculated the mold temperature, the polymer surface temperature, the heat flux, and the residual stress based on self-built thermal conduction model and achieved the good agreement M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT from the experimental results.…”