Optimizing performance for cooling electronic components using innovative heterogeneous materials

The relentless advancement of electronic devices has led to increased power densities, resulting in thermal challenges that threaten device reliability. This study aims to address this issue through the development of innovative heterogeneous materials for cooling electronic components. We focus on phase change materials (PCMs) impregnated within architected porous structures fabricated using additive manufacturing technology and 3D printing techniques. The objective is to leverage numerical simulations and additive manufacturing technology to select suitable materials and optimize heat dissipation within these structures. A comprehensive literature review of existing thermal management systems (TMS) for electronic devices, including mobile phones, laptops, and data centres, is presented. This review establishes a foundation for understanding the significance of TMS and introduces the benefits of employing PCMs in electronic devices. To assess the impact of the structure materials, we have run numerical simulations involving stainless steel, silver, Inconel, aluminium, copper, ti- tanium, and steel architected porous structures impregnated with palmitic acid as the PCM. The results demonstrate the superior heat dissipation of silver, copper, and aluminium porous structures, attributed to their higher thermal diffusivities. Other simulations explore PCMs with higher melting temperatures and latent heat capacities, considering specific application parameters like mobile phones and laptops. By integrating three organic PCMs (Myristic acid, Palmitic acid, and Stearic acid) within architected matrices, it offers a promising solution in the choice of PCMs to the challenges posed by high power densities in electronics. This approach deepens our understanding of the melting process and allows the optimization of heat transfer within architected structure

Thermal conductivity improvment of copper-carbon fiber composite by addition of an insulator : calcium hydroxide

The effects of adding calcium hydroxide (Ca(OH)2) to a copper-CF (30 %) composite (Cu-CF(30 %)) were studied. After sintering at 700 °C, precipitates of calcium oxide (CaO) were included in the copper matrix. When less than 10 % of Ca(OH)2 was added, the thermal conductivity was similar to or higher than the reference composite Cu-CF(30 %). A thermal conductivity of 322 W m−1 K−1 was measured for the Cu-Ca(OH)2(3 %)-CF(30 %) composite. The effects of heat treatment (400, 600, and 1000 °C during 24 h) on the composite Cu-Ca(OH)2(3 %)-CF(30 %) were studied. At the lower annealing temperature, CaO inside the matrix migrated to the interface of the copper matrix and the CF. At 1000 °C, the formation of the interphase calcium carbide (CaC2) at the interface of the copper and CFs was highlighted by TEM observations. Carbide formation at the interface led to a decrease in both thermal conductivity (around 270 W m−1 K−1) and the coefficient of thermal expansion (CTE (10.1 × 10−6 K−1))

Spectral evolution of Eu3+ doped Y3NbO7 niobate induced by temperature

A Eu3+ doped Y3NbO7 niobate powder was synthetized using a polymerizable complex route. It gave rise to nanometric particles that crystallized in the fluorine structure, corresponding to the Y3NbO7 phase. The thermal evolution of this powder was followed up to 1600 °C, using X-ray diffraction and optical characterizations. The fluorine structure was maintained in the whole temperature range. However, spectral evolution of the samples calcined above 900 °C showed a more complex situation. Emission spectra of powders heat treated at different temperatures showed an evolution of the emission lines that can be attributed first to a better crystallization of the niobate phase and second to its partial decomposition in favor of the formation of YNbO4 and Y2O3. Although the Y3NbO7 phase appeared stable up to 1650 °C, from X-ray diffraction analysis, spectral analysis showed that the local environment of the doping element is modified from 1100 °C.Initiative d'excellence de l'Université de Bordeau

Stress and phase purity analyses of diamond films deposited through laser-assisted combustion synthesis

Diamond films were deposited on silicon and tungsten carbide substrates in open air through laser-assisted combustion synthesis. Laser-induced resonant excitation of ethylene molecules was achieved in the combustion process to promote diamond growth rate. In addition to microstructure study by scanning electron microscopy, Raman spectroscopy was used to analyze the phase purity and residual stress of the diamond films. High-purity diamond films were obtained through laser-assisted combustion synthesis. The levels of residual stress were in agreement with corresponding thermal expansion coefficients of diamond, silicon, and tungsten carbide. Diamond-film purity increases while residual stress decreases with an increasing film thickness. Diamond films deposited on silicon substrates exhibit higher purity and lower residual stress than those deposited on tungsten carbide substrates