The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Rolf Brendel - One of the best experts on this subject based on the ideXlab platform.
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Laser Microwelding of thin Al layers for interconnection of crystalline Si solar cells: analysis of process limits for ns and μs Lasers
Journal of Photonics for Energy, 2014Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Sarah Kajari-schröder, Rolf BrendelAbstract:Leibniz University of Hanover, Institute for Solid-State Physics, Appelstrasse 2,Hannover 30167, GermanyAbstract. We investigated a Laser welding process for contacting aluminum-metallized crystal-line silicon solar cells to a 10-μm-thick aluminum layer on a glass substrate. We analyzed thethreshold for Laser-induced damage in dependence on the solar cell metallization thickness byapplying the process on SiNx passivated lifetime samples. In addition, we measured themechanical failure stress of the Laser welds by perpendicular tear-off. We applied two typesof Laser processes; one used single or multiple 20-ns-Laser pulses at 355 nm with fluencesbetween 12 and 40 J∕cm
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Aluminum-Based Mechanical and Electrical Laser Interconnection Process for Module Integration of Silicon Solar Cells
IEEE Journal of Photovoltaics, 2012Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Robert Bock, Agnes Merkle, Rolf BrendelAbstract:In this paper, an interconnection method for the module integration of silicon solar cells by Laser Microwelding of the Al-metalized rear side of the solar cell to a metalized substrate is introduced. This Laser Microwelding process forms a direct mechanical and electrical connection between two Al-layers without the need for any soldering, conductive adhesives, or Ag-pastes. With a tensile tester, we measure tear-off stresses of up to 303 kPa for our Laser weld spots. Furthermore, carrier lifetime measurements show that no defects are induced into the Si-crystal by the Laser process over a wide range of Laser pulse energies and number of Laser pulses. In order to demonstrate the applicability of this Laser-based interconnection method, we present a proof-of-concept module consisting of five n-type back-junction back-contact solar cells with a conversion efficiency of 20.0%.
Y. Zhou - One of the best experts on this subject based on the ideXlab platform.
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Joining of platinum (Pt) alloy wires to stainless steel wires for electronic medical devices
Joining and Assembly of Medical Materials and Devices, 2014Co-Authors: A. Pequegnat, Y. ZhouAbstract:Abstract: The joining of dissimilar materials in medical-device applications is necessary to increase flexibility in design, enhance performance, and reduce material costs. This chapter will discuss the joining of platinum alloy wires to stainless steel wires in the crossed-wire joint configuration, providing a solid introduction to the challenges that accompany the joining of dissimilar materials in non-standard joint geometries. Example studies utilizing the resistance Microwelding and Laser Microwelding processes are provided along with the process conditions required to produce sound joints.
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Femtosecond Laser-induced Microwelding of silver and copper.
Applied Optics, 2013Co-Authors: H. Huang, Peng Peng, Walter W. Duley, Y. ZhouAbstract:Femtosecond (fs) Laser irradiation has been shown to be effective for welding transparent materials and for transparent materials to metals. However, to date there is little work regarding similar applications in welding/bonding of metals. In this article, we for the first time to the best of our knowledge report on fs Laser-induced Microwelding of Ag microwires and Cu substrates. The influence of Laser pulse number and fluence on fs Laser Microwelding is studied to explore an optimum welding window. Morphology analysis indicates that the primary weld of the Ag microwire and the Cu substrate was located at the edge of the Ag microwire and produced via the redeposition and local melting-induced welding of the ablated materials.
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Crossed-Wire Laser Microwelding of Pt-10 Pct Ir to 316 LVM Stainless Steel: Part II. Effect of Orientation on Joining Mechanism
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2012Co-Authors: Y. D. Huang, Guisheng Zou, A. Pequegnat, M. I. Khan, J. C. Feng, Y. ZhouAbstract:With the increasing complexity of medical devices and with efforts to reduce manufacturing costs, challenges arise in joining dissimilar materials. In this study, the Laser weldability of dissimilar joints between Pt-10 pct Ir and 316 low-carbon vacuum melted (LVM) stainless steel (SS) crossed wires was investigated by characterizing the weld geometry, joint strength, morphology of weld cross sections, and differences in joining behavior, depending on which material is subject to the incident Laser beam. With the Pt-Ir alloy on top, a significant amount of porosity was observed on the surface of the welds as well as throughout the weld cross sections. This unique form of porosity is believed to be a result of preferential vaporization of 316 LVM SS alloying elements that become mixed with the molten Pt-10 pct Ir during welding. The joining mechanism documented in micrographs of cross-sectioned welds was found to transition from Laser brazing to fusion welding. It is inferred that the orientation of the two dissimilar metals (i.e., which material is subject to the incident Laser beam) plays an important role in weld quality of crossed-wire Laser welds.
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Crossed-Wire Laser Microwelding of Pt-10 Pct Ir to 316 Low-Carbon Vacuum Melted Stainless Steel: Part I. Mechanism of Joint Formation
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2011Co-Authors: Guisheng Zou, Y. D. Huang, A. Pequegnat, M. I. Khan, Y. ZhouAbstract:The excellent biocompatibility and corrosion properties of Pt alloys and 316 low-carbon vacuum melted (LVM) stainless steel (SS) make them attractive for biomedical applications. With the increasing complexity of medical devices and in order to lower costs, the challenge of joining dissimilar materials arises. In this study, Laser Microwelding (LMW) of crossed Pt-10 pct Ir to 316 LVM SS wires was performed and the weldability of these materials was determined. The joint geometry, joining mechanism, joint breaking force (JBF), and fracture modes were investigated using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and microtensile testing. It was shown that the mechanisms of joint formation transitioned from (1) brazing, (2) a combination of brazing and fusion welding, and (3) fusion welding with increasing pulsed Laser energy. The joints demonstrated various tensile failure modes including (1) interfacial failure below a peak power of 0.24 kW, (2) partial interfacial failure that propagated into the Pt-Ir wire, (3) failure in the Pt-Ir wire, and (4) failure in the SS wire due to porosity and severe undercutting caused by overwelding. During this study, the optimal Laser peak power range was identified to produce joints with good joint geometry and 90 pct of the tensile strength of the Pt-10 pct Ir wire.
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mechanical and functional properties of Laser welded ti 55 8 wt pct ni nitinol wires
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2011Co-Authors: M. I. Khan, Y. ZhouAbstract:As interest increases in incorporating Nitinol alloys in different microapplications and devices, the development of effective procedures for Laser Microwelding (LMW) these alloys becomes necessary. Laser welding processes applied to Nitinol have been shown to lower strength, induce inclusions of intermetallic compounds (IMCs), and alter the pseudoelastic and shape memory effects. Inconsistency in reported weld properties has also suggested that further studies are required. The current study details the mechanical, microstructural, and phase transformation properties of Nd:YAG LMW crossed Ti-55.8 wt pct Ni Nitinol wires. The effects of surface oxide on joint performance were also investigated. Fracture strength, weld microstructure, and phase transformation temperatures at varying peak power inputs were studied and compared to the unaffected base metal. Results showed good retention of strength and pseudoelastic properties, while the fusion zone exhibited higher phase transformation temperatures, which altered the active functional properties at room temperature.
Henning Schulte-huxel - One of the best experts on this subject based on the ideXlab platform.
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Laser Microwelding of thin Al layers for interconnection of crystalline Si solar cells: analysis of process limits for ns and μs Lasers
Journal of Photonics for Energy, 2014Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Sarah Kajari-schröder, Rolf BrendelAbstract:Leibniz University of Hanover, Institute for Solid-State Physics, Appelstrasse 2,Hannover 30167, GermanyAbstract. We investigated a Laser welding process for contacting aluminum-metallized crystal-line silicon solar cells to a 10-μm-thick aluminum layer on a glass substrate. We analyzed thethreshold for Laser-induced damage in dependence on the solar cell metallization thickness byapplying the process on SiNx passivated lifetime samples. In addition, we measured themechanical failure stress of the Laser welds by perpendicular tear-off. We applied two typesof Laser processes; one used single or multiple 20-ns-Laser pulses at 355 nm with fluencesbetween 12 and 40 J∕cm
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Aluminum-Based Mechanical and Electrical Laser Interconnection Process for Module Integration of Silicon Solar Cells
IEEE Journal of Photovoltaics, 2012Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Robert Bock, Agnes Merkle, Rolf BrendelAbstract:In this paper, an interconnection method for the module integration of silicon solar cells by Laser Microwelding of the Al-metalized rear side of the solar cell to a metalized substrate is introduced. This Laser Microwelding process forms a direct mechanical and electrical connection between two Al-layers without the need for any soldering, conductive adhesives, or Ag-pastes. With a tensile tester, we measure tear-off stresses of up to 303 kPa for our Laser weld spots. Furthermore, carrier lifetime measurements show that no defects are induced into the Si-crystal by the Laser process over a wide range of Laser pulse energies and number of Laser pulses. In order to demonstrate the applicability of this Laser-based interconnection method, we present a proof-of-concept module consisting of five n-type back-junction back-contact solar cells with a conversion efficiency of 20.0%.
Susanne Blankemeyer - One of the best experts on this subject based on the ideXlab platform.
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Laser Microwelding of thin Al layers for interconnection of crystalline Si solar cells: analysis of process limits for ns and μs Lasers
Journal of Photonics for Energy, 2014Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Sarah Kajari-schröder, Rolf BrendelAbstract:Leibniz University of Hanover, Institute for Solid-State Physics, Appelstrasse 2,Hannover 30167, GermanyAbstract. We investigated a Laser welding process for contacting aluminum-metallized crystal-line silicon solar cells to a 10-μm-thick aluminum layer on a glass substrate. We analyzed thethreshold for Laser-induced damage in dependence on the solar cell metallization thickness byapplying the process on SiNx passivated lifetime samples. In addition, we measured themechanical failure stress of the Laser welds by perpendicular tear-off. We applied two typesof Laser processes; one used single or multiple 20-ns-Laser pulses at 355 nm with fluencesbetween 12 and 40 J∕cm
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Aluminum-Based Mechanical and Electrical Laser Interconnection Process for Module Integration of Silicon Solar Cells
IEEE Journal of Photovoltaics, 2012Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Robert Bock, Agnes Merkle, Rolf BrendelAbstract:In this paper, an interconnection method for the module integration of silicon solar cells by Laser Microwelding of the Al-metalized rear side of the solar cell to a metalized substrate is introduced. This Laser Microwelding process forms a direct mechanical and electrical connection between two Al-layers without the need for any soldering, conductive adhesives, or Ag-pastes. With a tensile tester, we measure tear-off stresses of up to 303 kPa for our Laser weld spots. Furthermore, carrier lifetime measurements show that no defects are induced into the Si-crystal by the Laser process over a wide range of Laser pulse energies and number of Laser pulses. In order to demonstrate the applicability of this Laser-based interconnection method, we present a proof-of-concept module consisting of five n-type back-junction back-contact solar cells with a conversion efficiency of 20.0%.
Robert Bock - One of the best experts on this subject based on the ideXlab platform.
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Aluminum-Based Mechanical and Electrical Laser Interconnection Process for Module Integration of Silicon Solar Cells
IEEE Journal of Photovoltaics, 2012Co-Authors: Henning Schulte-huxel, Susanne Blankemeyer, Robert Bock, Agnes Merkle, Rolf BrendelAbstract:In this paper, an interconnection method for the module integration of silicon solar cells by Laser Microwelding of the Al-metalized rear side of the solar cell to a metalized substrate is introduced. This Laser Microwelding process forms a direct mechanical and electrical connection between two Al-layers without the need for any soldering, conductive adhesives, or Ag-pastes. With a tensile tester, we measure tear-off stresses of up to 303 kPa for our Laser weld spots. Furthermore, carrier lifetime measurements show that no defects are induced into the Si-crystal by the Laser process over a wide range of Laser pulse energies and number of Laser pulses. In order to demonstrate the applicability of this Laser-based interconnection method, we present a proof-of-concept module consisting of five n-type back-junction back-contact solar cells with a conversion efficiency of 20.0%.
