Enhanced heat transfer through filler-polymer interface by surface-coupling agent in heat-dissipation material: A non-equilibrium molecular dynamics study

Abstract

Developing a composite material of polymers and micrometer-sized fillers with higher heat conductance is crucial to realize modular packaging of electronic components at higher densities. Enhancement mechanisms of the heat conductance of the polymer-filler interfaces by adding the surface-coupling agent in such a polymer composite material are investigated through the non-equilibrium molecular dynamics (MD) simulation. A simulation system is composed of α-alumina as the filler, bisphenol-A epoxy molecules as the polymers, and model molecules for the surface-coupling agent. The inter-atomic potential between the α-alumina and surface-coupling molecule, which is essential in the present MD simulation, is constructed to reproduce the calculated energies with the electronic density-functional theory. Through the non-equilibrium MD simulation runs, we find that the thermal resistance at the interface decreases significantly by increasing either number or lengths of the surface-coupling molecules and that the effective thermal conductivity of the system approaches to the theoretical value corresponding to zero thermal-resistance at the interface. Detailed analyses about the atomic configurations and local temperatures around the interface are performed to identify heat-transfer routes through the interface.

A molecular dynamics study on thermal conductivity of thin epoxy polymer sandwiched between alumina fillers in heat-dissipation composite material

“…Since the O atom at the end of the SC molecule bonds tightly to a surface Al atom in the electronic density-functional theory (DFT) with PBE-GGA, we use the Al-O potential calculated by the DFT and fitted to the Morse form as explained in Ref. [20]. For the remaining inter-atomic potentials between a-alumina and SC molecules as well as the inter-atomic potentials between a-alumina and bisA molecules, we adopt the dispersion and Coulomb terms in the CMAS and Dreiding with the Lorentz-Berthelot mixing rule (i.e., arithmetic and geometric means for the diameter and energy factors, respectively).…”

“…We set the time step dt = 1.0 fs from detailed analyses [20] about the dt-dependencies of the temperature profile and energy flux in preparation runs. We omit H atoms in calculating the temperature profile.…”

“…As for the situation of small packing fraction of fillers, we investigated the effects of the SC molecules on the interfacial thermal conductance by considering the interface system of thick polymers and filler [20]. The bisphenol-A (bisA) epoxy molecules were considered for the polymers, a-alumina for the filler, and a model molecule for the SC.…”

Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

“…Scaling of device dimensions has enabled performance enhancement but as a trade-off scaled devices experience higher leakage current induced excessive power consumption in their idle state. [1][2][3][4][5][6][7] This also results into higher heat dissipation and eventually lower battery lifetime. With increased demand for ultra-mobile electronics, this rapid power draining acts as one of the main show stoppers.…”

High-performance epoxy/silica coated silver nanowire composites as underfill material for electronic packaging

“…However, the poor thermal conductivity of epoxy and the complex packaging process have limited its development [2][3][4]. To date, it is still a challenging task to design and fabricate high-performance epoxy-based underfill materials (EUMs) with excellent thermal conductivity (P1 W/mK), high glass transition temperature (>125°C), high electrical insulation and low viscosity (<20 Pa s at 25°C) [5,6].…”