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Keywords
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- Life cycle assessment; Solder; Sinter; Die-attach; Power electronics; Environment (1)
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Year of publication
Document Type
- Article (24)
- Conference Proceeding (9)
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Ecological comparison of soldering and sintering as die-attach technologies in power electronics
(2015)
In this study the method of life cycle assessment is used to perform a comparison of two die-attach technologies of power modules: silver sintering and common soldering with a tin–silver–copper solder. The goal of the study is to indicate which die-attach technique is more environmentally friendly. This is important in order to design future electronics more environmentally friendly.
Processing covers the manufacturing of the respective pastes, application of pastes, and mounting as well as the subsequent sintering or soldering, including cleaning of the soldered parts. The last step in the processing is a wire bonding process. The environmental impacts are expressed in CO2-equivalents and ReCiPe points and different variants are discussed: comparisons are made between considered pastes and between a soldered and a sintered power module, including consideration of lifetime. Concerning sintering, the influence of using recycled silver is analyzed more closely. The types of stages included in this life cycle assessment best fit a cradle-to-gate assessment, because usage, recycling, and disposal are not included. The software used is OpenLCA version 1.3.3, created by GreenDelta, and the database used is Ecoinvent version 2.2. In order to fill data gaps, electronics manufacturing companies were contacted, and our own calculations and measurements were applied.
The consideration of the wet film thicknesses of the soldering system and sintering system, respectively, results in very similar CO2-equivalent emissions for sinter paste and solder paste. Comparing the soldered power module to the sintered one shows minor to significant differences between the two systems which could easily be changed when changing circumstances and assumptions. But when considering the respective lifetimes of the joining technologies, sintering technology is clearly preferable to the conventional soldering technology. Using solely recycled silver for manufacturing of silver sinter paste reduces the CO2-equivalent emissions of one sintered power module by roughly 40%.
The results clearly show the dependence of outcomes on the initial settings. Consideration of lifetime has an enormous impact on the comparison of soldering technology to sintering technology. But the benefit of this life extension through the use of sintering technology is only useful when a long lifetime is required.
In this paper, we present two nondestructive characterization methods for the detection of voids in rear local contacts of passivated emitter and rear-type solar cells, namely scanning acoustic microscopy and computer tomography. We compare both methods and include a comparison with electroluminescence measurements. It is shown in this paper that voids can easily be detected with both measurement types without any sample preparation. We found a good match of scanning acoustic microscopy (SAM) and computer tomography (CT), which is presented for this purpose for the first time. The investigation was carried out for different aluminum pastes.
Intelligente Pedelecs fördern. Ein Ansatz zur nachhaltigen Verbesserung unseres Mobilitätsverhaltens
(2016)
Vergleich der thermischen Eigenschaften unterschiedlicher insulated metal substrat-Leiterplatten
(2010)
This article proposes and demonstrates a robust microstructure-based fiber-to-chip coupling scheme for planar Bragg grating devices. A polymer planar Bragg grating substrate is manufactured and microstructured by means of a micromilling process, while the respective photonic structures are generated by employing a sophisticated single-writing UV-exposure method. A stripped standard single mode fiber is inserted into the microstructure, which is filled with a UV-curable adhesive, and aligned with the integrated waveguide. After curing, final sensor assembly and thermal treatment, the proposed coupling scheme is capable of withstanding pressures up to 10 bar, at room temperature, and pressures up to 7.5 bar at an elevated temperature of 120 °C. Additionally, the coupling scheme is exceedingly robust towards tensile forces, limited only by the tensile strength of the employed single mode fiber. Due to its outstanding robustness, the coupling scheme enables the application of planar Bragg grating devices in harsh environments. This fact is underlined by integrating a microstructure-coupled photonic device into the center of a commercial-grade carbon fiber-reinforced polymer specimen. After its integration, the polymer-based Bragg grating sensor still exhibits a reflection peak with a dynamic range of 24 dB, and can thus be employed for sensing purposes.
This contribution discusses the integration of polymer planar Bragg grating sensors (PPBG) into carbon fiber reinforced polymer (CFRP) components. For the first time, it is shown that PPBGs based on cyclic olefin copolymers can be integrated into commercial-grade composites, thereby withstanding the demanding production processes. Pre-impregnated fibers are stacked and partially modified to form a sensor pocket. Afterwards, the CFRP specimen containing the optical sensor is cured in a heated mechanical press for 2 hours at a pressure of 7 bar and a temperature of 120 °C. A subsequent evalutaion of the sensor signal shows a Bragg wavelength shift of 1236 pm and a decline in signal amplitude of -2 dB. Three-point flexural tests of the cured sample reveal a linear behavior of the sensor signal towards external loads. The determined sensitivity in dependence of the CFRP specimen's maximum central deflection is -112 pm/mm, while correlation to the applied force results in a sensitivity of -5 pm/N.
This contribution demonstrates the functionality of polymer planar Bragg grating (PPBG) sensors integrated into commercial-grade carbon fiber reinforced polymer (CFRP) components. Multiple CFRP specimens are generated by curing a stack of pre-impregnated fibers inside of a heated mechanical press, exposing the polymer sensor to a pressure of 7 bar and a temperature of 120 °C for 2 h. After integration, the sensor still exhibits a strong and evaluable signal. Subsequent flexural experiments reveal a linear response of the integrated sensor’s Bragg wavelength to the CFRP specimen’s maximum deflection. Additional findings demonstrate that the embedded PPBG can be used to detect plastic deformations of a CFRP workpiece, whereas a linear correlation of plastic deformation to the resulting Bragg signal offset is determined. A plausibility check of the obtained results is delivered by a comparison of three-point flexural experiments on bulk CFRP workpieces, without integrated sensors and additional specimens featuring external optical sensors affixed to their surface. It is found that PPBGs based on cyclic olefin copolymers are able to overcome the temperature-related limitations of traditional polymer-based optical sensors and can thus be directly integrated into commercial-grade composites during production.
This study demonstrates mobile load monitoring of a composite bicycle component using an application-
customized polymer planar Bragg grating sensor, evaluated by a mobile interrogation unit. After a referencing procedure, the mechanical load of a seat post is monitored while cycling through a test track.