TY - JOUR A1 - Liu, E A1 - Conti, Fosca A1 - Bhogaraju, Sri Krishna A1 - Signorini, Raffaella A1 - Pedron, Danilo A1 - Wunderle, Bernhard A1 - Elger, Gordon T1 - Thermomechanical stress in GaN-LEDs soldered onto Cu substrates studied using finite element method and Raman spectroscopy JF - Journal of Raman Spectroscopy N2 - Local thermomechanical stress can cause failures in semiconductor packages during long-time operation under harsh environmental conditions. This study helps to explain the packaging-induced stress in blue GaN-LEDs soldered onto copper substrates using AuSn alloy as lead-free interconnect material. Based on the finite element method, a virtual prototype is developed to simulate the thermomechanical behavior and stress in the LED and in the complete LED/AuSn/Cu assembly considering plastic and viscoplastic strain. The investigations were performed by varying the temperature between −50°C and 180°C. To validate the model, the simulation results are compared to experimental data collected with Raman spectroscopy. Studies of the urn:x-wiley:03770486:media:jrs5947:jrs5947-math-0003 phonon mode of GaN semiconductor are elaborated to understand the induced thermomechanical stress. The model enables evaluation of the stress in the interfaces of the assembly, which otherwise cannot be accessed by measurements. It serves to predict how assemblies would perform, before committing resources to build a physical prototype. UR - https://doi.org/10.1002/jrs.5947 KW - finite element method KW - gallium nitride (GaN) KW - LED KW - semiconductor KW - thermomechanical stress Y1 - 2020 UR - https://doi.org/10.1002/jrs.5947 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-9438 SN - 1097-4555 VL - 51 IS - 10 SP - 2083 EP - 2094 PB - Wiley CY - Chichester ER - TY - CHAP A1 - Liu, E A1 - Conti, Fosca A1 - Bhogaraju, Sri Krishna A1 - Elger, Gordon T1 - Simulations and experiments to analyze stress phenomena in soldered and sintered interconnections between silicon nitride chips and copper substrates T2 - 2021 22nd International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) UR - https://doi.org/10.1109/EuroSimE52062.2021.9410869 KW - Performance evaluation KW - Analytical models KW - Compressive stress KW - Thermomechanical processes KW - Data models KW - Microelectronics KW - Finite element analysis Y1 - 2021 UR - https://doi.org/10.1109/EuroSimE52062.2021.9410869 SN - 978-1-6654-1373-2 PB - IEEE CY - Piscataway ER - TY - JOUR A1 - Schmid, Maximilian A1 - Bhogaraju, Sri Krishna A1 - Liu, E A1 - Elger, Gordon T1 - Comparison of Nondestructive Testing Methods for Solder, Sinter, and Adhesive Interconnects in Power and Opto-Electronics JF - Applied Sciences N2 - Reliability is one of the major requirements for power and opto-electronic devices across all segments. High operation temperature and/or high thermomechanical stress cause defects and degradation of materials and interconnects, which may lead to malfunctions with costly or even life-threatening consequences. To avoid or at least reduce failures, nondestructive testing (NDT) methods are common within development and production of power and opto-electronics. Currently, the dominating NDT methods are X-ray, scanning acoustic microscopy (SAM), and transient thermal analysis (TTA). However, they have different strengths and weaknesses with respect to materials and mechanical designs. This paper compares these NDT methods for different interconnect technologies, i.e., reflow soldering, adhesive, and sintered interconnection. While X-ray provided adequate results for soldered interfaces, inspection of adhesives and sintered interconnects was not possible. With SAM, evaluation of adhesives and sintered interconnects was also feasible, but quality depended strongly on the sample under test. TTA enabled sufficiently detailed results for all the interconnect applications. Automated TTA equipment, as the in-house developed tester used within this investigation, enabled measurement times compatible with SAM and X-ray. In the investigations, all methods revealed their pros and cons, and their selection has to depend on the sample under tests and the required analysis depth and data details. In the paper, guidelines are formulated for an appropriate decision on the NDT method depending on sample and requirements. UR - https://doi.org/10.3390/app10238516 KW - reliability KW - nondestructive testing KW - power electronics KW - X-ray KW - scanning acoustic microscopy KW - transient thermal analysis KW - TTA KW - sintering KW - LED KW - MOSFET Y1 - 2020 UR - https://doi.org/10.3390/app10238516 UR - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:573-12518 SN - 2076-3417 VL - 10 IS - 23 PB - MDPI CY - Basel ER - TY - CHAP A1 - Pascucci, Jacopo A1 - Conti, Fosca A1 - Bhogaraju, Sri Krishna A1 - Signorini, Raffaella A1 - Liu, E A1 - Pedron, Danilo A1 - Elger, Gordon ED - Cheben, Pavel ED - Čtyroký, Jiří ED - Molina-Fernández, Iñigo T1 - Micro-Raman to detect stress phenomena in Si-chips bonded onto Cu substrates T2 - Integrated Optics: Design, Devices, Systems and Applications VI UR - https://doi.org/10.1117/12.2576414 Y1 - 2021 UR - https://doi.org/10.1117/12.2576414 SN - 978-1-5106-4385-7 N1 - Poster + Paper PB - SPIE CY - Bellingham ER - TY - CHAP A1 - Conti, Fosca A1 - Liu, E A1 - Bhogaraju, Sri Krishna A1 - Wunderle, Bernhard A1 - Elger, Gordon T1 - Finite Element simulations and Raman measurements to investigate thermomechanical stress in GaN-LEDs T2 - 2020 IEEE 8th Electronics System-Integration Technology Conference (ESTC) UR - https://doi.org/10.1109/ESTC48849.2020.9229843 KW - finite element method KW - gallium nitride (GaN) KW - LED KW - Raman spectroscopy KW - semiconductor KW - thermomechanical stress Y1 - 2020 UR - https://doi.org/10.1109/ESTC48849.2020.9229843 SN - 978-1-7281-6293-5 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Conti, Fosca A1 - Liu, E A1 - Bhogaraju, Sri Krishna A1 - Lenz, Christoph A1 - Seitz, Roland A1 - Elger, Gordon T1 - Stress evaluations of silicon nitride chips bonded onto copper substrates via SAC soldering, AuSn soldering, and copper sintering T2 - 2020 26th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) UR - https://doi.org/10.1109/THERMINIC49743.2020.9420523 KW - Creep KW - Thermomechanical processes KW - Silicon nitride KW - Copper KW - Plastics KW - Microstructure KW - Soldering Y1 - 2021 UR - https://doi.org/10.1109/THERMINIC49743.2020.9420523 SN - 978-1-7281-7643-7 SP - 204 EP - 208 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Liu, E A1 - Schmid, Maximilian A1 - Bhogaraju, Sri Krishna A1 - Elger, Gordon T1 - Advanced location resolved transient thermal analysis T2 - 2020 26th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) UR - https://doi.org/10.1109/THERMINIC49743.2020.9420538 KW - Temperature measurement KW - Semiconductor device measurement KW - Thermal resistance KW - Thermal conductivity KW - Dielectric measurement KW - Thermal analysis KW - Dielectrics Y1 - 2021 UR - https://doi.org/10.1109/THERMINIC49743.2020.9420538 SN - 978-1-7281-7643-7 SP - 191 EP - 196 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Zippelius, Andreas A1 - Hanss, Alexander A1 - Liu, E A1 - Schmid, Maximilian A1 - Pérez-Velázquez, Judith A1 - Elger, Gordon T1 - Comparing prediction methods for LED failure measured with Transient Thermal Analysis T2 - 2020 21st International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) UR - https://doi.org/10.1109/EuroSimE48426.2020.9152657 KW - Temperature measurement KW - Artificial neural networks KW - Light emitting diodes KW - Aging KW - Current measurement KW - Training KW - Heating systems Y1 - 2020 UR - https://doi.org/10.1109/EuroSimE48426.2020.9152657 SN - 978-1-7281-6049-8 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Hanss, Alexander A1 - Liu, E A1 - Abdullah, Muhammad Rizwan A1 - Elger, Gordon T1 - Failure Identification in LED packages by Transient Thermal Analysis and Calibrated FE Models T2 - 2019 20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) UR - https://doi.org/10.1109/EuroSimE.2019.8724558 KW - Conferences KW - Microelectronics KW - Micromechanical devices KW - Light emitting diodes KW - Aluminum nitride KW - III-V semiconductor materials Y1 - 2019 UR - https://doi.org/10.1109/EuroSimE.2019.8724558 SN - 978-1-5386-8040-7 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Elger, Gordon A1 - Liu, E A1 - Conti, Fosca A1 - Signorini, Raffaella A1 - Brugnolotto, Enrico A1 - Bhogaraju, Sri Krishna T1 - Modelling Thermo-Mechanical Stress in GaN-LEDs Soldered on Copper Substrate with Simulations Validated by Raman Experiments T2 - 2019 20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) UR - https://doi.org/10.1109/EuroSimE.2019.8724533 KW - Conferences KW - Microelectronics KW - Micromechanical devices Y1 - 2019 UR - https://doi.org/10.1109/EuroSimE.2019.8724533 SN - 978-1-5386-8040-7 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Signorini, Raffaella A1 - Conti, Fosca A1 - Brugnolotto, Enrico A1 - Pedron, Danilo A1 - Liu, E A1 - Bhogaraju, Sri Krishna A1 - Elger, Gordon ED - Cheben, Pavel ED - Čtyroký, Jiří ED - Molina-Fernández, Iñigo T1 - Thermomechanical local stress in assembled GaN LEDs investigated by Raman optical spectroscopy T2 - Integrated Optics: Design, Devices, Systems, and Applications V UR - https://doi.org/10.1117/12.2520992 Y1 - 2019 UR - https://doi.org/10.1117/12.2520992 SN - 978-1-5106-2729-1 N1 - Presentation + Paper PB - SPIE CY - Bellingham ER - TY - CHAP A1 - Brugnolotto, Enrico A1 - Bhogaraju, Sri Krishna A1 - Liu, E A1 - Conti, Fosca A1 - Pedron, Danilo A1 - Signorini, Raffaella A1 - Elger, Gordon T1 - Investigation of thermomechanical local stress induced in assembled GaN LEDs T2 - 2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) UR - https://doi.org/10.1109/THERMINIC.2019.8923629 Y1 - 2019 UR - https://doi.org/10.1109/THERMINIC.2019.8923629 SN - 978-1-7281-2078-2 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Schmid, Maximilian A1 - Hermann, Joseph A1 - Liu, E A1 - Elger, Gordon T1 - Correlation of Scanning Acoustic Microscopy and Transient Thermal Analysis to Identify Crack Growth in Solder Joints T2 - Proceedings of the Twenty First InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems: ITherm 2022 UR - https://doi.org/10.1109/iTherm54085.2022.9899664 KW - reliability KW - transient thermal analysis (TTA) KW - scanning acoustic microscopy (SAM) KW - finite element simulation KW - finite element optimization KW - LED KW - solder KW - crack Y1 - 2022 UR - https://doi.org/10.1109/iTherm54085.2022.9899664 SN - 978-1-6654-8503-6 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Liu, E A1 - Bhogaraju, Sri Krishna A1 - Lux, Kerstin A1 - Elger, Gordon A1 - Mou, Rokeya Mumtahana T1 - Investigation Of Stress Generated By Interconnection Processes With Micro-Raman Spectroscopy (μRS) T2 - Proceedings IEEE 72nd Electronic Components and Technology Conference: ECTC 2022 UR - https://doi.org/10.1109/ECTC51906.2022.00123 KW - component KW - μ-Raman Spectroscopy KW - Au80Sn20 KW - Cu sintering KW - finite element simultion Y1 - 2022 UR - https://doi.org/10.1109/ECTC51906.2022.00123 SN - 978-1-6654-7943-1 SP - 739 EP - 745 PB - IEEE CY - Piscataway ER - TY - JOUR A1 - Hanss, Alexander A1 - Schmid, Maximilian A1 - Liu, E A1 - Elger, Gordon T1 - Transient thermal analysis as measurement method for IC package structural integrity JF - Chinese Physics B UR - https://doi.org/10.1088/1674-1056/24/6/068105 Y1 - 2015 UR - https://doi.org/10.1088/1674-1056/24/6/068105 SN - 2058-3834 SN - 1674-1056 VL - 24 IS - 6 PB - IOP Publishing CY - Bristol ER - TY - CHAP A1 - Bhogaraju, Sri Krishna A1 - Schmid, Maximilian A1 - Liu, E A1 - Saccon, Rodolfo A1 - Elger, Gordon A1 - Klassen, Holger A1 - Müller, Klaus A1 - Pirzer, Georg T1 - Low cost copper based sintered interconnect material for optoelectronics packaging T2 - 2022 IEEE 72nd Electronic Components and Technology Conference (ECTC) UR - https://doi.org/10.1109/ECTC51906.2022.00270 KW - Cu sintering KW - flakes KW - PEG600 KW - reliability KW - encapsulation KW - oxidation KW - transient thermal analysis KW - Scanning acoustic microscopy KW - μ-Raman spectroscopy Y1 - 2022 UR - https://doi.org/10.1109/ECTC51906.2022.00270 SN - 978-1-6654-7943-1 SP - 1720 EP - 1725 PB - IEEE CY - Piscataway ER - TY - JOUR A1 - Liu, E A1 - Bhogaraju, Sri Krishna A1 - Wunderle, Bernhard A1 - Elger, Gordon T1 - Investigation of stress relaxation in SAC305 with micro-Raman spectroscopy JF - Microelectronics Reliability UR - https://doi.org/10.1016/j.microrel.2022.114664 Y1 - 2022 UR - https://doi.org/10.1016/j.microrel.2022.114664 SN - 0026-2714 VL - 2022 IS - 138 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Conti, Fosca A1 - Lux, Kerstin A1 - Bhogaraju, Sri Krishna A1 - Liu, E A1 - Lenz, Christoph A1 - Seitz, Roland A1 - Elger, Gordon ED - Baldini, Francesco ED - Homola, Jiri ED - Lieberman, Robert A. T1 - Raman spectroscopy to investigate gallium nitride light emitting diodes after assembling onto copper substrates T2 - Optical Sensors 2021 UR - https://doi.org/10.1117/12.2591947 Y1 - 2021 UR - https://doi.org/10.1117/12.2591947 SN - 978-1-5106-4379-6 N1 - Poster + Paper PB - SPIE CY - Bellingham ER - TY - CHAP A1 - Liu, E A1 - Mohd, Zubair Akhtar A1 - Steinberger, Fabian A1 - Wunderle, Bernhard A1 - Elger, Gordon T1 - Using µ-RAMAN Spectroscopy to Inspect Sintered Interconnects T2 - 2024 IEEE 10th Electronics System-Integration Technology Conference (ESTC), Proceedings UR - https://doi.org10.1109/ESTC60143.2024.10712149 Y1 - 2024 UR - https://doi.org10.1109/ESTC60143.2024.10712149 SN - 979-8-3503-9036-0 PB - IEEE CY - Piscataway ER -