Characterization of Multifunctional Nanomaterials for Electronics Thermal Management and Sintering Applications
Doctoral thesis, 2021
Due to their high surface to volume ratio, nanoscale particles show different thermodynamics properties that led to their potential implementation in electronics fabrication processes. More specifically, silver nanoparticles (Ag NPs) have been under focus in recent years for applications to replace lead-free solder and contribute to energy saving. Due to a poor trade-off between the process parameters, the production costs, and the reliability of the silver related application, different strategies are being suggested to optimize its applications. In this present study, we investigate multiple sintering parameters of Ag NPs and use the nanoscale effect in a hybrid approach for the sintering of microscopic powder. The results of the sintering parameters are correlated to the density of the samples and their properties in terms of thermal and electrical conductivity. While the sintering of Ag NPs occurs at low temperatures and allows to obtain relatively high densities, the thermal and electrical properties are still limited and the increase in the temperature and fraction of the NPs higher than 400 degrees and 2wt.% has a much- pronounced effect to improve the physical properties of the samples.
The sintering of Ag NPs was also explored in this thesis to propose a novel approach to use graphene foam as a heat sink. While graphene is known for its outstanding physical, chemical, and mechanical properties, its integration as a practical solution in electronics is still missing. The use of Ag NPs in this work allowed to successfully attach the 3D graphene foam on its substrate and further improve both its mechanical and thermal properties by coating the graphene with Ag NPs. Also, the integration of Ag NPs as a die-attach for the 3D porous structure allowed its further use as a container for Phase Change Materials (PCM). Different amounts of PCM were introduced in the lightweight foam and the junction temperature of the hot spot was correlated to the power and the presence of the PCM. We found that graphene foam presents a real advantage for its use in thermal dissipation strategies.
2D graphene material is developed herein as a coating for micro-and nanoscale particles. Using Chemical Vapor Deposition (CVD) and Arc Discharge (AD) methods, we introduce the possibility to produce graphene coating on copper particles for application in thermal management. In addition, we explore the possibility to introduce a doping effect on the coated NPs to further study its effect on the thermal performances of NPs. The morphology and the composition of the coating were investigated and correlated with the bottom-up production process of CVD and AD. The thermal conductivity and chemical stability of the produced particles were studied for their use as fillers in thermally conductive pastes and additives water-based nanofluids. The thermal properties of the different systems were linked to the fraction of the additives and nanofillers. The graphene-coated particles were found to have a multifunctional effect. In both micro-and nanoscale particles, the graphene coating was found to act as a corrosion resistance that stabilizes the metallic core of the particles. The graphene coating also was found to act as a carbon source to reduce the microparticles in a bimodal powder at high temperatures. Finally, the encapsulation of the nanoscale powder allowed to observe a melting point depression related to the composition of the core of the nanoparticles and their nanoscale size.
In an effort to combine the size effect of the nanoparticles and their compositions, different alloyed nanoparticles were produced using AC. The morphology, the composition, and their sintering properties were compared to highlight their composition effect. The produced nanopowders were also used as a sintering aid in the spark plasma sintering approach (SPS) and the results show a positive contribution of the nanopowders in the reduction of the sintering temperature and the densification of the samples. An additional effect is also reported and arises from the possibility to use those particles to fine-tune the chemical composition of the bimodal particles.
Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems
Low-Temperature Sintering Bimodal Micro Copper-Nano Silver for Electrical Power Devices
2018 7th Electronic System-Integration Technology Conference (ESTC),; (2018)
Paper in proceeding
High porosity and light weight graphene foam heat sink and phase change material container for thermal management
Nanotechnology,; Vol. 31(2020)
Manufacturing Graphene-Encapsulated Copper Particles by Chemical Vapor Deposition in a Cold Wall Reactor
ChemistryOpen,; Vol. 8(2019)p. 58-63
Exploring Graphene Coated Copper Nanoparticles as a Multifunctional Nanofiller for Micro-Scaled Copper Paste, Zehri, A., Nilsson, T., Fu, Y., Liu, J.
Graphene-coated copper nanoparticles for thermal conductivity enhancement in water-based nanofluid
2019 22nd European Microelectronics and Packaging Conference and Exhibition, EMPC 2019,; (2019)
Paper in proceeding
Graphene Oxide and Nitrogen-Doped Graphene Coated Copper Nanoparticles in Water-Based Nanofluids for Thermal Management in Electronics, Zehri A., Nylander, A., Nilsson, T., Ye, L., Fu, Y., Liu, J.
Characterisation of Nanosized Low Carbon Steel Alloy Based Nanopowder As a Sintering Aid For Spark Plasma Sintering process, Zehri A., Zhang Y., Aboulfadl H., Cao Y., Sögaard C., Ye L., Palmqvist A., A., Nyborg L., Nilsson T.M.J., Fu F., Liu J.
In this work, we bridge the nanoscale world with the reality of the modern processing and manufacturing context where sustainability is at its core. The concept of equality moved from an intra-generational issue to an inter-generational ethical topic, where finite resources should be exploited wisely. In such a context, the combination of the size of the nanoparticles and their compositions can become a game-changer. Throughout this work, we exploit the low processing temperatures of nanoparticles to propose new methods to produce multifunctional materials used in heat dissipation strategies in
electronic and low-temperature manufacturing. We put an effort to connect the top-down method to the bottom-up energy- and materials-efficient production strategy, where we explore the arc discharge process to produce new alloy-based nanoparticles that are used as a sintering aid for
spark plasma sintering. Using the same production route, we also report on new types of materials that have the potential to be integrated into advanced thermal management solutions.
At the beginning of this thesis, we asked three fundamental questions that are related to the integration of nanomaterials in heat management in electronics and low-temperature sintering:
- Can nanoscale materials be integrated further into the heat dissipation of modern electronics?
- How can graphene-based materials benefit from new structures of fillers and is it possible to use
modern production solutions to manufacture even more advanced graphene fillers?
- How can non-conventional manufacturing processes benefit from the use of nanoscale materials
To answer these questions, we conducted a set of experiments and explored new approaches where we show the potential of using nanomaterials in modern processing and manufacturing. To the question on whether the nanoscale can be further implemented in the heat dissipation strategies,
we answer yes, and in many ways! The nanoscale effect that originates from the high surface energy of the particles can be used in modern electronics in the fabrication of components and interconnections but also to integrate other heat transfer solutions that bring further enhancement
into the thermal capability of the electronic package. To the question on how new structured graphene-based powders can further be used in the service of advanced heat dissipation solutions, we answer that the supported graphene on the spherical substrate allows an optimal orientation to the heat transfer and might result in a continuous increase in the thermal conductivity of thermally conductive adhesive and waterbased nanofluids, but that will depend largely on the right condition on the structure and stability of the core/shell spherical particles. To the question of how modern sintering technics can exploit the nanoscale materials, we answer that the key is to dare to explore the variation of the chemical composition of the nanoparticles to take
full control of the potential of the nanoscale material in the future of electronics and beyond.
Nanotechnology Enhanced Sintered Steel Processing
Swedish Foundation for Strategic Research (SSF) (GMT14-0045), 2016-01-01 -- 2020-12-31.
Enhanced cement based coating materials for surface protection/repair applications using 2-dimentional materials
Formas (FR-2017/0009), 2018-01-01 -- 2020-12-31.
Areas of Advance
Nanoscience and Nanotechnology (SO 2010-2017, EI 2018-)
Chalmers Materials Analysis Laboratory
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5057
Kollektorn, MC2 building
Opponent: Changqing Liu, Loughborough University, United Kingdom