Thermal Conduction in Vertically Aligned Copper Nanowire Arrays and Composites

Abstract

The ability to efficiently and reliably transfer heat between sources and sinks is often a bottleneck in the thermal management of modern energy conversion technologies ranging from microelectronics to thermoelectric power generation. These interfaces contribute parasitic thermal resistances that reduce device performance and are subjected to thermomechanical stresses that degrade device lifetime. Dense arrays of vertically aligned metal nanowires (NWs) offer the unique combination of thermal conductance from the constituent metal and mechanical compliance from the high aspect ratio geometry to increase interfacial heat transfer and device reliability. In the present work, we synthesize copper NW arrays directly onto substrates via templated electrodeposition and extend this technique through the use of a sacrificial overplating layer to achieve improved uniformity. Furthermore, we infiltrate the array with an organic phase change material and demonstrate the preservation of thermal properties. We use the 3ω method to measure the axial thermal conductivity of freestanding copper NW arrays to be as high as 70 W m(-1) K(-1), which is more than an order of magnitude larger than most commercial interface materials and enhanced-conductivity nanocomposites reported in the literature. These arrays are highly anisotropic, and the lateral thermal conductivity is found to be only 1-2 W m(-1) K(-1). We use these measured properties to elucidate the governing array-scale transport mechanisms, which include the effects of morphology and energy carrier scattering from size effects and grain boundaries.

Thermal Transport in 3D Nanostructures

“…We will discuss the thermal conductivity of NW array‐based composite in Section . NW arrays can be prepared via electrodeposition ( Figure a) or biotemplate mask (Figure b) …”

“…14, Reproduced from ref. 15, Reproduced with permission . Copyright 2015, American Chemical Society.…”

Ultrahigh Thermal Conductivity of Interface Materials by Silver‐Functionalized Carbon Nanotube Phonon Conduits

“…[5][6][7][8][9][10] The volume fraction of fillers needs to be minimized, while achieving high κ, to maintain good printability and economic viability. [3,9] Nanocarbon materials such as carbon nanotubes (CNTs) and graphene have also been investigated actively because of the high intrinsic κ (≈1000-10 000 W m…”

“…[19,27,28] The electrical and thermal transport properties of nAg-MWNT-Ag-flake-epoxy and Ag-flake-epoxy TIMs are compared as a function of the curing duration ( Figure 3). As shown in Figure 3a, the σ of nAgMWNT-Ag-flake-epoxy TIMs was [3] orange open up-pointing triangle (silver nanoparticle 45 vol%), [6] blue open down-pointing triangle (aluminum nitride 74 vol%), [7] dark cyan open diamond (iodine-treated silver 35 vol%), [8] wine open star (silver epoxy plus graphene 5 vol%), [9] violet open pentagon (copper nanowire arrays 25 vol%), [10] magenta open left-pointing triangle (graphite 25 vol%), [11] dark yellow open right-pointing triangle (aligned MWNT 16.7 vol%), [12] navy open hexagon (MWNT 25 vol% plus graphene 25 vol%), [13] pink open inverted triangle (silver 70 vol% plus MWNT 3.1 vol%). [33] Half-filled symbols: olive half-filled pentagon (boron nitride nanosheet 50 vol%), [34] purple half-filled hexagon (carbon nanosheet 33 vol%).…”

Recent Advances on 3D Printing Technique for Thermal‐Related Applications

“…[64,65] However, these techniques still lack the ability to adequately control, are time consuming, and limited to achieve large-scale production. Different alignment methods have been investigated, such as electrical flocking, magnetic field assisted alignment, and rolling.…”