Heat Conduction Across Corrugated Thermal Interface

2007 ◽  
Author(s):  
Bozhi Yang ◽  
Wenjun Liu
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Analytical Solution ◽  
High Performance ◽  
Fem Simulation ◽  
Expansion Method ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Eigenfunction Expansion Method ◽  
First Time

This paper presents the analytical solution of the heat conduction across a corrugated thermal interface material with rectangular straight fin arrangement. Domain decomposition and eigenfunction expansion method were used to study the thermal diffusion in such geometry for the first time. The temperature field solved from the analytical method agrees well with FEM simulation. The total heat transfer rate across the corrugated interface and thermal boundary resistance were derived analytically also. Results have shown that the effective thermal resistance across the interface can be significantly reduced with the corrugated TIM geometry. The analytical solution in the paper can provide insight into geometry effect on the heat transfer enhancement, and is a very useful complement to experimental work and numerical simulation in designing high-performance corrugated thermal interface.

scholarly journals Exact Analytical Solution for 3D Time-Dependent Heat Conduction in a Multilayer Sphere with Heat Sources Using Eigenfunction Expansion Method

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Nemat Dalir
Keyword(s):  
Heat Conduction ◽  
Analytical Solution ◽  
Eigenfunction Expansion ◽  
Radial Direction ◽  
Exact Analytical Solution ◽  
Internal Heat ◽  
Expansion Method ◽  
Time Dependent ◽  
Heat Sources ◽  
Eigenfunction Expansion Method

An exact analytical solution is obtained for the problem of three-dimensional transient heat conduction in the multilayered sphere. The sphere has multiple layers in the radial direction and, in each layer, time-dependent and spatially nonuniform volumetric internal heat sources are considered. To obtain the temperature distribution, the eigenfunction expansion method is used. An arbitrary combination of homogenous boundary condition of the first or second kind can be applied in the angular and azimuthal directions. Nevertheless, solution is valid for nonhomogeneous boundary conditions of the third kind (convection) in the radial direction. A case study problem for the three-layer quarter-spherical region is solved and the results are discussed.

scholarly journals RGO-Coated Polyurethane Foam/Segmented Polyurethane Composites as Solid–Solid Phase Change Thermal Interface Material

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3004
Author(s):  
Cong Zhang ◽  
Zhe Shi ◽  
An Li ◽  
Yang-Fei Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
High Performance ◽  
In Situ Polymerization ◽  
Solid Phase ◽  
Thermal Interface Material ◽  
Segmented Polyurethane ◽  
Thermal Interface ◽  
Self Assembling

Thermal interface material (TIM) is crucial for heat transfer from a heat source to a heat sink. A high-performance thermal interface material with solid–solid phase change properties was prepared to improve both thermal conductivity and interfacial wettability by using reduced graphene oxide (rGO)-coated polyurethane (PU) foam as a filler, and segmented polyurethane (SPU) as a matrix. The rGO-coated foam (rGOF) was fabricated by a self-assembling method and the SPU was synthesized by an in situ polymerization method. The pure SPU and rGOF/SPU composite exhibited obvious solid–solid phase change properties with proper phase change temperature, high latent heat, good wettability, and no leakage. It was found that the SPU had better heat transfer performance than the PU without phase change properties in a practical application as a TIM, while the thermal conductivity of the rGOF/SPU composite was 63% higher than that of the pure SPU at an ultra-low rGO content of 0.8 wt.%, showing great potential for thermal management.

Development of a High Performance Thermal Interface Material With Vertically Aligned Graphite Platelets

2011 ◽  
Author(s):  
Y. Zhao ◽  
D. Strauss ◽  
T. Liao ◽  
Y. C. Chen ◽  
C. L. Chen
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
High Performance ◽  
Experimental Tests ◽  
Thermal Interface Material ◽  
Graphite Nanoplatelets ◽  
Compression Pressure ◽  
Thermal Interface ◽  
Soldering Process ◽  
Vertically Aligned

This paper introduces a high performance thermal interface material (TIM) with vertically aligned graphite. The main structure of the TIM is a vertically laminated structure, in which thin solder layers are laminated with aligned graphite layers. Unlike traditional TIMs infiltrated with randomly oriented high conductive fillers, the laminated TIM with vertically aligned graphite provides extraordinarily high z-axis thermal conductivity and controllable stiffness by simply setting the thickness of each component layer to match different surfaces. Thus, this design greatly improves the overall heat transfer performance. In addition, using metallic-graphite composites greatly improves the bonding between the graphite and the metallic host compared to nonmetallic materials, and thus the thermal boundary resistance can be significantly reduced. Moreover, compared to organic hosts, solders have much smaller phonon spectra mismatch with graphite nanoplatelets (GNPs), and thus offer significantly higher interface conductance. Furthermore, vertically connected solder layers can also lock the graphite layers in place and reinforce the strength of the entire package. A series of experimental tests was conducted to evaluate the effects of processing pressure and surface roughness on the overall thermal performance of the graphite TIMs. The results indicated that the overall thermal resistance of two smooth surfaces soldered by a 200 μm-thick graphite TIM was reduced from 0.12 to 0.03 cm2•K/W when the compression pressure applied during the soldering process was increased from 7 to 68 psi. Increased surface roughness appeared to improve heat transfer across the interface by enlarging the contact areas between the surface and the graphite TIMs. A preliminary numerical simulation verified this trend.

A HIGH THROUGHPUT, LOW COST ASSEMBLY APPROACH FOR LED IMS PACKAGES TO HEAT SINK USING ADVANCED THERMAL INTERFACE MATERIALS

2015 ◽  
Vol 2015 (1) ◽  
pp. 000627-000632 ◽  
Author(s):  
Swapan K. Bhattacharya ◽  
Fei Xie ◽  
Han Wu ◽  
Kelley Hodge ◽  
Keck Pathammavong ◽  
...  
Keyword(s):  
Heat Sink ◽  
High Performance ◽  
High Reliability ◽  
Low Cost ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Cycle Times ◽  
High Adhesion ◽  
Machine Cycle

The objective of this study is to design and fabricate a high reliability LED Insulated Metal Substrate (IMS) package to complex heat sink attachment using an advanced thermal interface material (TIM). The assembly consists of LED IMS parts bonded to a heat spreader/sink using an advanced TIM and a corner bond material to quickly and accurately secure the LEDs in position. The corner bond adhesive is snap cured for fast machine cycle times while the high performance, high adhesion TIM materials cure throughout the rest of the assembly operation. This approach allows high accuracy LED bonding without the need for alignment pins or fasteners to anchor to the IMS. The IMS attached to the heat sink is then electrically interconnected with a thin flex substrate on top of the IMS. This approach is expected to replace the current mechanical fastners and low strength silicone TIM materials and reduce the cycle time and overall placement cost which are key drivers especially for the automotive industry.

scholarly journals An Analytical Solution for Transient Heat Conduction in a Composite Slab with Time-Dependent Heat Transfer Coefficient

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Ryoichi Chiba
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Conduction ◽  
Analytical Solution ◽  
Differential Equations ◽  
Transfer Coefficient ◽  
Transient Heat Conduction ◽  
External Boundary ◽  
Composite Slab ◽  
Composite Slabs

An analytical solution is derived for one-dimensional transient heat conduction in a composite slab consisting of n layers, whose heat transfer coefficient on an external boundary is an arbitrary function of time. The composite slab, which has thermal contact resistance at n-1 interfaces, as well as an arbitrary initial temperature distribution and internal heat generation, convectively exchanges heat at the external boundaries with two different time-varying surroundings. To obtain the analytical solution, the shifting function method is first used, which yields new partial differential equations under conventional types of external boundary conditions. The solution for the derived differential equations is then obtained by means of an orthogonal expansion technique. Numerical calculations are performed for two composite slabs, whose heat transfer coefficient on the heated surface is either an exponential or a trigonometric function of time. The numerical results demonstrate the effects of temporal variations in the heat transfer coefficient on the transient temperature field of composite slabs.

scholarly journals Use of 1D mechanical and thermal models to predetermine the heat transferable by a thermal interface material layer in space applications

2020 ◽  
Vol 234 (17) ◽  
pp. 3459-3473
Author(s):  
Simon Vandevelde ◽  
Alain Daidié ◽  
Marc Sartor
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Thermal Contact ◽  
Interface Layer ◽  
Thermal Interface Material ◽  
Space Applications ◽  
Thermal Interface ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Assistance Tool

This paper proposes the use of 1D basic models to build a design assistance tool capable of evaluating the heat transfer between a third-level electronic packaging and its support, considering a conventional configuration where a thermal interface material is placed between these two parts. Using this kind of tool early in the design process may facilitate choices concerning geometry and material. The packaging is modelled by a stepped beam (the equipment) and the interface layer by a nonlinear elastic foundation (the thermal interface material). Considering that the electronic equipment bends under the effect of the forces exerted by the fasteners, the tool makes it possible to determine the contact zone remaining operative after deformation, and the pressure distribution at the interface. Mechanical results are then used to calculate the steady-state heat transfer between the equipment and its support, taking into account the diffusion within the equipment and the thermal interface material, and also the thermal contact resistances, the latter being dependent on the contact pressure. A detailed case study is used to illustrate the utility of the approach. The 1D models are exploited to illustrate the interest of the design assistance tool. The influence of different parameters on the thermal performance is studied and a new innovative proposal is analyzed, which could lead to a significant increase in thermal performance.

Analytical Solution of Nonequilibrium Heat Conduction in Porous Medium Incorporating a Variable Porosity Model With Heat Generation

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. Nazari ◽  
F. Kowsary
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Transfer Coefficient ◽  
Heat Conduction ◽  
Analytical Solution ◽  
Transfer Coefficient ◽  
Heat Generation ◽  
Conductivity Ratio ◽  
Variable Porosity ◽  
Porosity Model

This paper is concerned with the conduction heat transfer between two parallel plates filled with a porous medium with uniform heat generation under a nonequilibrium condition. Analytical solution is obtained for both fluid and solid temperature fields at constant porosity incorporating the effects of thermal conductivity ratio, porosity, and a nondimensional heat transfer coefficient at pore level. The two coupled energy equations for the case of variable porosity condition are transformed into a third order ordinary equation for each phase, which is solved numerically. This transformation is a valuable solution for heat conduction regime for any distribution of porosity in the channel. The effects of the variable porosity on temperature distribution are shown and compared with the constant porosity model. For the case of the exponential decaying porosity distribution, the numerical results lead to a correlation incorporating conductivity ratio and interstitial heat transfer coefficient.

Exact Analytical Solution for Unsteady Heat Conduction in Fiber-Reinforced Spherical Composites Under the General Boundary Conditions

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
A. Amiri Delouei ◽  
M. Norouzi
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Analytical Solution ◽  
Boundary Conditions ◽  
Laplace Transformation ◽  
Exact Analytical Solution ◽  
Function Technique ◽  
Conductive Heat ◽  
Fiber Reinforced ◽  
Legendre Series

The current study presents an exact analytical solution for unsteady conductive heat transfer in multilayer spherical fiber-reinforced composite laminates. The orthotropic heat conduction equation in spherical coordinate is introduced. The most generalized linear boundary conditions consisting of the conduction, convection, and radiation heat transfer is considered both inside and outside of spherical laminate. The fibers' angle and composite material in each lamina can be changed. Laplace transformation is employed to change the domain of the solutions from time into the frequency. In the frequency domain, the separation of variable method is used and the set of equations related to the coefficients of Fourier–Legendre series is solved. Meromorphic function technique is utilized to determine the complex inverse Laplace transformation. Two functional cases are presented to investigate the capability of current solution for solving the industrial unsteady problems in different arrangements of multilayer spherical laminates.

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