@article{LiuContiBhogarajuetal.2020, author = {Liu, E and Conti, Fosca and Bhogaraju, Sri Krishna and Signorini, Raffaella and Pedron, Danilo and Wunderle, Bernhard and Elger, Gordon}, title = {Thermomechanical stress in GaN-LEDs soldered onto Cu substrates studied using finite element method and Raman spectroscopy}, volume = {51}, journal = {Journal of Raman Spectroscopy}, number = {10}, publisher = {Wiley}, address = {Chichester}, issn = {1097-4555}, doi = {https://doi.org/10.1002/jrs.5947}, pages = {2083 -- 2094}, year = {2020}, abstract = {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.}, language = {en} } @inproceedings{LiuContiBhogarajuetal.2021, author = {Liu, E and Conti, Fosca and Bhogaraju, Sri Krishna and Elger, Gordon}, title = {Simulations and experiments to analyze stress phenomena in soldered and sintered interconnections between silicon nitride chips and copper substrates}, booktitle = {2021 22nd International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-6654-1373-2}, doi = {https://doi.org/10.1109/EuroSimE52062.2021.9410869}, year = {2021}, language = {en} } @inproceedings{PascucciContiBhogarajuetal.2021, author = {Pascucci, Jacopo and Conti, Fosca and Bhogaraju, Sri Krishna and Signorini, Raffaella and Liu, E and Pedron, Danilo and Elger, Gordon}, title = {Micro-Raman to detect stress phenomena in Si-chips bonded onto Cu substrates}, booktitle = {Integrated Optics: Design, Devices, Systems and Applications VI}, editor = {Cheben, Pavel and Čtyrok{\´y}, Jiř{\´i} and Molina-Fern{\´a}ndez, I{\~n}igo}, publisher = {SPIE}, address = {Bellingham}, isbn = {978-1-5106-4385-7}, doi = {https://doi.org/10.1117/12.2576414}, year = {2021}, language = {en} } @inproceedings{BhogarajuSchmidHufnageletal.2021, author = {Bhogaraju, Sri Krishna and Schmid, Maximilian and Hufnagel, Elias and Conti, Fosca and Kotadia, Hiren R. and Elger, Gordon}, title = {Low temperature and low pressure die-attach bonding of high power light emitting diodes with self reducing copper complex paste}, booktitle = {IEEE 71st Electronic Components and Technology Conference ECTC 2021, Proceedings}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-6654-4097-4}, doi = {https://doi.org/10.1109/ECTC32696.2021.00094}, pages = {526 -- 531}, year = {2021}, language = {en} } @inproceedings{ContiLiuBhogarajuetal.2020, author = {Conti, Fosca and Liu, E and Bhogaraju, Sri Krishna and Wunderle, Bernhard and Elger, Gordon}, title = {Finite Element simulations and Raman measurements to investigate thermomechanical stress in GaN-LEDs}, booktitle = {2020 IEEE 8th Electronics System-Integration Technology Conference (ESTC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-6293-5}, doi = {https://doi.org/10.1109/ESTC48849.2020.9229843}, year = {2020}, language = {en} } @inproceedings{BhogarajuContiElger2020, author = {Bhogaraju, Sri Krishna and Conti, Fosca and Elger, Gordon}, title = {Copper die bonding using copper formate based pastes with α-terpineol, amino-2-propanol and hexylamine as binders}, booktitle = {2020 IEEE 8th Electronics System-Integration Technology Conference (ESTC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-6293-5}, doi = {https://doi.org/10.1109/ESTC48849.2020.9229801}, year = {2020}, language = {en} } @inproceedings{ContiLiuBhogarajuetal.2021, author = {Conti, Fosca and Liu, E and Bhogaraju, Sri Krishna and Lenz, Christoph and Seitz, Roland and Elger, Gordon}, title = {Stress evaluations of silicon nitride chips bonded onto copper substrates via SAC soldering, AuSn soldering, and copper sintering}, booktitle = {2020 26th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-7643-7}, doi = {https://doi.org/10.1109/THERMINIC49743.2020.9420523}, pages = {204 -- 208}, year = {2021}, language = {en} } @article{MokhtariContiSacconetal.2021, author = {Mokhtari, Omid and Conti, Fosca and Saccon, Rodolfo and Bhogaraju, Sri Krishna and Elger, Gordon}, title = {Formic acid and formate salts for chemical vapor deposition of copper on glass substrates at atmospheric pressure}, volume = {45}, journal = {New Journal of Chemistry}, number = {43}, publisher = {RSC}, address = {London}, issn = {1369-9261}, doi = {https://doi.org/10.1039/D1NJ02476K}, pages = {20133 -- 20139}, year = {2021}, language = {en} } @article{BhogarajuKotadiaContietal.2021, author = {Bhogaraju, Sri Krishna and Kotadia, Hiren R. and Conti, Fosca and Mauser, Armin and Rubenbauer, Thomas and Bruetting, Robert and Schneider-Ramelow, Martin and Elger, Gordon}, title = {Die-attach bonding with etched micro brass metal pigment flakes for high-power electronics packaging}, volume = {3}, journal = {ACS Applied Electronic Materials}, number = {10}, publisher = {ACS Publications}, address = {Washington}, issn = {2637-6113}, doi = {https://doi.org/10.1021/acsaelm.1c00721}, pages = {4587 -- 4603}, year = {2021}, language = {en} } @article{BhogarajuMokhtariContietal.2020, author = {Bhogaraju, Sri Krishna and Mokhtari, Omid and Conti, Fosca and Elger, Gordon}, title = {Die-attach bonding for high temperature applications using thermal decomposition of copper(II) formate with polyethylene glycol}, volume = {2020}, journal = {Scripta Materialia}, number = {182}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1359-6462}, doi = {https://doi.org/10.1016/j.scriptamat.2020.02.045}, pages = {74 -- 80}, year = {2020}, language = {en} } @article{BhogarajuContiKotadiaetal.2020, author = {Bhogaraju, Sri Krishna and Conti, Fosca and Kotadia, Hiren R. and Keim, Simon and Tetzlaff, Ulrich and Elger, Gordon}, title = {Novel approach to copper sintering using surface enhanced brass micro flakes for microelectronics packaging}, volume = {2020}, pages = {156043}, journal = {Journal of Alloys and Compounds}, number = {844}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4669}, doi = {https://doi.org/10.1016/j.jallcom.2020.156043}, year = {2020}, language = {en} } @article{MokhtariContiBhogarajuetal.2019, author = {Mokhtari, Omid and Conti, Fosca and Bhogaraju, Sri Krishna and Meier, Markus and Schweigart, Helmut and Tetzlaff, Ulrich and Elger, Gordon}, title = {Characterization of tin-oxides and tin-formate crystals obtained from SnAgCu solder alloy under formic acid vapor}, volume = {43}, journal = {New Journal of Chemistry}, number = {26}, publisher = {RSC}, address = {London}, issn = {1369-9261}, doi = {https://doi.org/10.1039/C9NJ02135C}, pages = {10227 -- 10231}, year = {2019}, language = {en} } @inproceedings{BhogarajuContiSchmidetal.2020, author = {Bhogaraju, Sri Krishna and Conti, Fosca and Schmid, Maximilian and Meier, Markus and Schweigart, Helmut and Elger, Gordon}, title = {Development of sinter paste with surface modified copper alloy particles for die-attach bonding}, booktitle = {ETG-Fachbericht 161, CIPS 2020, 11th International Conference on Integrated Power Electronics Systems}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-5226-3}, url = {https://www.vde-verlag.de/proceedings-de/455225100.html}, pages = {582 -- 587}, year = {2020}, language = {en} } @inproceedings{ElgerLiuContietal.2019, author = {Elger, Gordon and Liu, E and Conti, Fosca and Signorini, Raffaella and Brugnolotto, Enrico and Bhogaraju, Sri Krishna}, title = {Modelling Thermo-Mechanical Stress in GaN-LEDs Soldered on Copper Substrate with Simulations Validated by Raman Experiments}, booktitle = {2019 20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-5386-8040-7}, doi = {https://doi.org/10.1109/EuroSimE.2019.8724533}, year = {2019}, language = {en} } @inproceedings{ElgerMokhtariBhogarajuetal.2020, author = {Elger, Gordon and Mokhtari, Omid and Bhogaraju, Sri Krishna and Conti, Fosca and Meier, Markus and Schweigart, Helmut}, title = {Analyse der Reaktionsprodukte von Metall-Formiaten im r{\"u}ckstandfreien L{\"o}tprozess}, booktitle = {GMM-Fb. 94: EBL 2020 - Elektronische Baugruppen und Leiterplatten}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-5185-3}, doi = {https://www.vde-verlag.de/proceedings-de/455185053.html}, year = {2020}, language = {de} } @inproceedings{BhogarajuMokhtariPascuccietal.2019, author = {Bhogaraju, Sri Krishna and Mokhtari, Omid and Pascucci, Jacopo and Conti, Fosca and Kotadia, Hiren R. and Elger, Gordon}, title = {A multi-pronged approach to low-pressure Cu sintering using surface-modified particles, substrate and chip metallization}, volume = {2019}, booktitle = {International Symposium on Microelectronics}, number = {1}, publisher = {IMAPS}, address = {Pittsburgh}, issn = {2380-4505}, doi = {https://doi.org/10.4071/2380-4505-2019.1.000387}, pages = {387 -- 392}, year = {2019}, language = {en} } @inproceedings{BhogarajuMokhtariPascuccietal.2019, author = {Bhogaraju, Sri Krishna and Mokhtari, Omid and Pascucci, Jacopo and Conti, Fosca and Elger, Gordon}, title = {Improved sinterability of particles to substrates by surface modifications on substrate metallization}, volume = {2019}, booktitle = {Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT)}, number = {HiTen}, publisher = {IMAPS}, address = {Pittsburgh (PA)}, issn = {2380-4491}, doi = {https://doi.org/10.4071/2380-4491.2019.HiTen.000066}, pages = {66 -- 70}, year = {2019}, language = {en} } @inproceedings{SignoriniContiBrugnolottoetal.2019, author = {Signorini, Raffaella and Conti, Fosca and Brugnolotto, Enrico and Pedron, Danilo and Liu, E and Bhogaraju, Sri Krishna and Elger, Gordon}, title = {Thermomechanical local stress in assembled GaN LEDs investigated by Raman optical spectroscopy}, booktitle = {Integrated Optics: Design, Devices, Systems, and Applications V}, editor = {Cheben, Pavel and Čtyrok{\´y}, Jiř{\´i} and Molina-Fern{\´a}ndez, I{\~n}igo}, publisher = {SPIE}, address = {Bellingham}, isbn = {978-1-5106-2729-1}, doi = {https://doi.org/10.1117/12.2520992}, year = {2019}, language = {en} } @inproceedings{BrugnolottoBhogarajuLiuetal.2019, author = {Brugnolotto, Enrico and Bhogaraju, Sri Krishna and Liu, E and Conti, Fosca and Pedron, Danilo and Signorini, Raffaella and Elger, Gordon}, title = {Investigation of thermomechanical local stress induced in assembled GaN LEDs}, booktitle = {2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-2078-2}, doi = {https://doi.org/10.1109/THERMINIC.2019.8923629}, year = {2019}, language = {en} } @inproceedings{HanssSchmidBhogarajuetal.2018, author = {Hanss, Alexander and Schmid, Maximilian and Bhogaraju, Sri Krishna and Conti, Fosca and Elger, Gordon}, title = {Reliability of sintered and soldered high power chip size packages and flip chip LEDs}, booktitle = {ECTC - The 2018 IEEE 68th Electronic Components and Technology Conference: Proceedings}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-5386-5000-4}, doi = {https://doi.org/10.1109/ECTC.2018.00312}, pages = {2080 -- 2088}, year = {2018}, language = {en} } @inproceedings{BhogarajuMokhtariPascuccietal.2020, author = {Bhogaraju, Sri Krishna and Mokhtari, Omid and Pascucci, Jacopo and Hanss, Alexander and Schmid, Maximilian and Conti, Fosca and Elger, Gordon}, title = {Hybrid Cu particle paste with surface-modified particles for high temperature electronics packaging}, booktitle = {Proceedings 22nd European Microelectronics and Packaging Conference, EMPC}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-6291-1}, doi = {https://doi.org/10.23919/EMPC44848.2019.8951887}, year = {2020}, language = {en} } @inproceedings{HanssSchmidBhogarajuetal.2018, author = {Hanss, Alexander and Schmid, Maximilian and Bhogaraju, Sri Krishna and Conti, Fosca and Elger, Gordon}, title = {Process development and reliability of sintered high power chip size packages and flip chip LEDs}, booktitle = {2018 International Conference on Electronics Packaging and iMAPS All Asia Conference (ICEP-IAAC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-4-9902-1885-0}, doi = {https://doi.org/10.23919/ICEP.2018.8374351}, pages = {479 -- 484}, year = {2018}, language = {en} } @inproceedings{BhogarajuHanssSchmidetal.2018, author = {Bhogaraju, Sri Krishna and Hanss, Alexander and Schmid, Maximilian and Elger, Gordon and Conti, Fosca}, title = {Evaluation of silver and copper sintering of first level interconnects for high power LEDs}, booktitle = {2018 7th Electronic System-Integration Technology Conference (ESTC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-5386-6814-6}, doi = {https://doi.org/10.1109/ESTC.2018.8546499}, year = {2018}, language = {en} } @article{ContiHanssMokhtarietal.2018, author = {Conti, Fosca and Hanss, Alexander and Mokhtari, Omid and Bhogaraju, Sri Krishna and Elger, Gordon}, title = {Formation of tin-based crystals from a SnAgCu alloy under formic acid vapor}, volume = {42}, journal = {New Journal of Chemistry}, number = {23}, publisher = {RSC}, address = {London}, issn = {1369-9261}, doi = {https://doi.org/10.1039/C8NJ04173C}, pages = {19232 -- 19236}, year = {2018}, language = {en} } @inproceedings{SignoriniPedronContietal.2018, author = {Signorini, Raffaella and Pedron, Danilo and Conti, Fosca and Hanss, Alexander and Bhogaraju, Sri Krishna and Elger, Gordon}, title = {Thermomechanical Stress in GaN LED Soldered on Copper Substrate Evaluated by Raman Measurements and Computer Modelling}, booktitle = {2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-5386-6759-0}, doi = {https://doi.org/10.1109/THERMINIC.2018.8593304}, year = {2018}, language = {en} } @inproceedings{BhogarajuSchmidKotadiaetal.2021, author = {Bhogaraju, Sri Krishna and Schmid, Maximilian and Kotadia, Hiren R. and Conti, Fosca and Elger, Gordon}, title = {Highly reliable die-attach bonding with etched brass flakes}, booktitle = {2021 23rd European Microelectronics and Packaging Conference \& Exhibition (EMPC): Technical Papers}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-0-9568086-7-7}, doi = {https://doi.org/10.23919/EMPC53418.2021.9584967}, year = {2021}, language = {en} } @inproceedings{ContiLuxBhogarajuetal.2021, author = {Conti, Fosca and Lux, Kerstin and Bhogaraju, Sri Krishna and Liu, E and Lenz, Christoph and Seitz, Roland and Elger, Gordon}, title = {Raman spectroscopy to investigate gallium nitride light emitting diodes after assembling onto copper substrates}, booktitle = {Optical Sensors 2021}, editor = {Baldini, Francesco and Homola, Jiri and Lieberman, Robert A.}, publisher = {SPIE}, address = {Bellingham}, isbn = {978-1-5106-4379-6}, doi = {https://doi.org/10.1117/12.2591947}, year = {2021}, language = {en} }