| 1. |
- Bournias-Varotsis, A., et al.
(författare)
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Selectively anodised aluminium foils as an insulating layer for embedding electronic circuitry in a metal matrix via ultrasonic additive manufacturing
- 2016
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Ingår i: Solid Freeform Fabrication 2016. - : Laboratory for Freeform Fabrication. ; , s. 2260-2270
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Konferensbidrag (refereegranskat)abstract
- Ultrasonic Additive Manufacturing (UAM) is a hybrid Additive Manufacturing (AM) process that involves layer-by-layer ultrasonic welding of metal foils and periodic machining to achieve the desired shape. Prior investigative research has demonstrated the potential of UAM for the embedding of electronic circuits inside a metal matrix. In this paper, a new approach for the fabrication of an insulating layer between an aluminium (Al) matrix and embedded electronic interconnections is presented. First, an Anodic Aluminium Oxide (AAO) layer is selectively grown onto the surface of Al foils prior to bonding. The pre-treated foils are then welded onto a UAM fabricated aluminium substrate. The bonding step can be repeated for the full encapsulation of the electronic interconnections or components. This ceramic AAO insulating layer provides several advantages over the alternative organic materials used in previous works.
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| 2. |
- Li, J., et al.
(författare)
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Exploring the mechanical performance and material structures of integrated electrical circuits within solid state metal additive manufacturing matrices
- 2014
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Ingår i: Proceedings of the Twenty-Fifth Annual International Solid Freeform Fabrication (SFF) Symposium – An Additive Manufacturing Conference. ; , s. 857-864
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Konferensbidrag (refereegranskat)abstract
- Ultrasonic Additive Manufacturing (UAM) enables the integration of a wide variety of components into solid metal matrices due to a high degree of metal plastic flow at low matrix bulk temperatures. This phenomenon allows the fabrication of previously unobtainable novel engineered metal matrix components. The aim of this paper was to investigate the compatibility of electronic materials with UAM, thus exploring an entirely new realm of multifunctional components by integration of electrical structures within dense metal components processed in the solid-state. Three different dielectric materials were successfully embedded into UAM fabricated metal-matrices with, research derived, optimal processing parameters. The effect of dielectric material hardness on the final metal matrix mechanical strength after UAM processing was investigated systematically via mechanical peel testing and microscopy. The research resulted in a quantification of the role of material hardness on final UAM sample mechanical performance, which is of great interest for future industrial applications.
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| 3. |
- Li, J., et al.
(författare)
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Exploring the mechanical strength of additively manufactured metal structures with embedded electrical materials
- 2015
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Ingår i: Journal of Materials Science and Engineering. - New York, NY : David Publishing Company. - 2161-6213 .- 0921-5093. ; 639, s. 474-481
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasonic Additive Manufacturing (UAM) enables the integration of a wide variety of components into solid metal matrices due to the process induced high degree of metal matrix plastic flow at low bulk temperatures. Exploitation of this phenomenon allows the fabrication of previously unobtainable novel engineered metal matrix components.The feasibility of directly embedding electrical materials within UAM metal matrices was investigated in this work. Three different dielectric materials were embedded into UAM fabricated aluminium metal-matrices with, research derived, optimal processing parameters. The effect of the dielectric material hardness on the final metal matrix mechanical strength after UAM processing was investigated systematically via mechanical peel testing and microscopy. It was found that when the Knoop hardness of the dielectric film was increased from 12.1 HK/0.01 kg to 27.3 HK/0.01 kg, the mechanical peel testing and linear weld density of the bond interface were enhanced by 15% and 16%, respectively, at UAM parameters of 1600 N weld force, 25 µm sonotrode amplitude, and 20 mm/s welding speed. This work uniquely identified that the mechanical strength of dielectric containing UAM metal matrices improved with increasing dielectric material hardness. It was therefore concluded that any UAM metal matrix mechanical strength degradation due to dielectric embedding could be restricted by employing a dielectric material with a suitable hardness (larger than 20 HK/0.01 kg). This result is of great interest and a vital step for realising electronic containing multifunctional smart metal composites for future industrial applications. © 2015 The Authors.
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| 4. |
- Bournias-Varotsis, Alkaios, et al.
(författare)
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The effect of ultrasonic excitation on the electrical properties and microstructure of printed electronic conductive inks
- 2015
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Ingår i: 2015 38th International Spring Seminar on Electronics Technology (ISSE). - 9781479988600 - 9781479988594 ; , s. 140-145
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Konferensbidrag (refereegranskat)abstract
- Ultrasonic Additive Manufacturing (UAM) is an advanced manufacturing technique, which enables the embedding of electronic components and interconnections within solid aluminium structures, due to the low temperature encountered during material bonding. In this study, the effects of ultrasonic excitation, caused by the UAM process, on the electrical properties and the microstructure of thermally cured screen printed silver conductive inks were investigated. The electrical resistance and the dimensions of the samples were measured and compared before and after the ultrasonic excitation. The microstructure of excited and unexcited samples was examined using combined Focused Ion Beam and Scanning Electron Microscopy (FIB/SEM) and optical microscopy. The results showed an increase in the resistivity of the silver tracks after the ultrasonic excitation, which was correlated with a change in the microstructure: the size of the silver particles increased after the excitation, suggesting that inter-particle bonding has occurred. The study also highlighted issues with short circuiting between the conductive tracks and the aluminium substrate, which were attributed to the properties of the insulating layer and the inherent roughness of the UAM substrate. However, the reduction in conductivity and observed short circuiting were sufficiently small and rare, which leads to the conclusion that printed conductive tracks can function as interconnects in conjunction with UAM, for the fabrication of novel smart metal components.
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| 5. |
- Bournias-Varotsis, Alkaios, et al.
(författare)
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Ultrasonic Additive Manufacturing as a form-then-bond process for embedding electronic circuitry into a metal matrix
- 2018
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Ingår i: Journal of Manufacturing Processes. - London : Elsevier. - 1526-6125. ; 32, s. 664-675
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasonic Additive Manufacturing (UAM) is a hybrid manufacturing process that involves the layer-by-layer ultrasonic welding of metal foils in the solid state with periodic CNC machining to achieve the desired 3D shape. UAM enables the fabrication of metal smart structures, because it allows the embedding of various components into the metal matrix, due to the high degree of plastic metal flow and the relatively low temperatures encountered during the layer bonding process. To further the embedding capabilities of UAM, in this paper we examine the ultrasonic welding of aluminium foils with features machined prior to bonding. These pre-machined features can be stacked layer-by-layer to create pockets for the accommodation of fragile components, such as electronic circuitry, prior to encapsulation. This manufacturing approach transforms UAM into a “form-then-bond” process. By studying the deformation of aluminium foils during UAM, a statistical model was developed that allowed the prediction of the final location, dimensions and tolerances of pre-machined features for a set of UAM process parameters. The predictive power of the model was demonstrated by designing a cavity to accommodate an electronic component (i.e. a surface mount resistor) prior to its encapsulation within the metal matrix. We also further emphasised the importance of the tensioning force in the UAM process. The current work paves the way for the creation of a novel system for the fabrication of three-dimensional electronic circuits embedded into an additively manufactured complex metal composite. © 2018 The Society of Manufacturing Engineers
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