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Power electronics packaging
Microelectronics Reliability 55 (2015) 2523
Contents lists available at ScienceDirect
Microelectronics Reliability journal homepage: www.elsevier.com/locate/mr
Guest Editorial
Power electronics packaging Katsuaki Suganuma a, Jenn-Ming Song b, Yi-Shao Lai c a b c
Institute of Science and Industrial Research, Osaka University, Japan Department of Materials Science and Engineering, National Chung Hsing University, Taiwan Advanced Semiconductor Engineering, Inc., Taiwan
Power electronics plays one of the key roles in the generation-storagedistribution conversion cycle of the electric energy that contributes to the development of the sustainable world. New integration technology for power devices has been rapidly developed to fulfill the demands for high power density, high operation temperature and improved reliability at the same time of system miniaturizations. Present-day technologies and materials are unable to deal with the emerging problems. There are high expectations for wide band gap (WBG) power semiconductors, such as SiC and GaN devices, because they can be operated in extreme conditions where silicon power devices cannot work anymore — in environments over 200 °C, for example. Bringing out the full potential of WBG power devices requires completely new approaches covering all relevant technologies extending from structural design, electrical design, and packaging. With respect to packaging technology, innovations in materials, manufacturing techniques and reliability evaluation are inevitable. The paper included is divided into four groups, interconnection materials, damaging mechanism of solder interconnects, interface design for electric/thermal contact, and Packaging design and performance. Nano-Ag sinter joining, which is one of the most emerging materials for die-attach especially for high power applications, was reported by the first paper on wide band gap devices by X. Li and the second paper on power laser by Y. Mei. X. Li studied high temperature stability of nano-Ag sintered joints of Cu and revealed the excellent stability up to 250 °C to 960 h in vacuum while serious strength degradation occurred after aging at 250 °C only for 72 h in air. Oxidation of Cu has a key to maintain the interface integrity. Y. Mei studied on a pulse reliability investigation of high power single emitter laser modules with nano-Ag paste. Y. Mei compared the life time of a laser diode die-attached with nano-Ag sinter joining with In and Au–Sn solderings by experiment aided with FEM. He provided a semi-empirical model based on Arrhenius relationship that is established to provide relative reliability assessments for laser modules. R. Mahmudi reported on creep behavior of Zn–4Al–3Mg–xSn alloys tested by impression technique and found that increasing Sn content of alloys increased creep rate, which can be attributed to the soft Sn-rich phase and lack of hard Mg–Zn particles. Y. H. Chen reported on a new Al–Cu intermetallic metallization for soldering and identified the reaction phases. Damaging mechanism of solder interconnects were reported by two papers, Numbers 5 and 6. T. Kadoguchi reported on electromigration at the interface between Sn–Cu and Ni–P plating at elevated temperature and pointed out that electromigration accelerates the diffusion of Ni in E-mail addresses: [email protected] (K. Suganuma), samsong@ nchu.edu.tw (J.-M. Song), [email protected] (Y.-S. Lai).
http://dx.doi.org/10.1016/j.microrel.2015.11.014 0026-2714/© 2015 Published by Elsevier Ltd.
the Ni–P plating at the cathode, which enhances the growth of a Ni depleted zone while the Ni diffusion at the anode side is depressed. P. Rajaguru proposed a proposed time dependent damage indicator model for a die-attach structure soldered with Sn–3.5Ag under irregular temperature change. In the part of interface design for electric/thermal contact, three papers are involved from number 7 to 9. M. Fujino reported on the bumpshaped vertically aligned multi-walled carbon nanotubes bonded to a Au substrate by a surface activated bonding. They found that Ar fast atom bombardment for 1200 s improves the interconnect resistance by 1/1000 of the original resistance. J. W. Yang proposed a unique method to increase orhmic contact performance by depositing Al2O3 nanoparticles on AlGaN/GaN before Au metallization which is attributed to the suppression of excess reaction between the metallization and the substrate during annealing process. Y. Xuan reported on graphene mixed with epoxy as thermal interface material. They found that the smallest thermal contact resistance is achieved with 6 wt% graphene primarily influenced by the hardness of the composite. In the 4th part of the current special issue, packaging design and performance, four papers are included from numbers 10 to 13. G. Q. Lu studied on the design procedure and experimental verification of a thermal characterization system for IGBT modules. They found nano-Ag sinter die-attach gives 12 % lower Zth (transient thermal impedance) than SAC solder. C.-C. Lee proposed an embedded IGBT module for the reduction of inductance at the same time of attractive miniaturization. M.-Y. Tsai reported on solution for cracking problem of a direct-plated-copper aluminum nitride substrate with excellent thermal conductivity. They employed warpage measurement combined with FEM analysis. Finally, J. Li studied on the failure of several types of Si IGBT configurations on a DBC substrate under overcurrent. The configurations are the conventional Al wire bonding, flexible PCB interconnect and DBC supported flexible PCB. Thus, the current special issue is intended to stretch our steps into the new world of interconnect technology especially for the extreme environmental conditions for power devices including Si and wide band gap semiconductors. It is our pleasure that many papers have been submitted to this issue. Among them, 13 excellent papers are involved in the current issue. As briefly summarized above, they are ranging from the individual interconnection materials such as solders and sinter joining, wire bonding, interconnect performance, and reliability issues such as thermal exposure/cycling, and electromigration. The editors are hoping that all those new findings in papers will provide some new insights and ideas to the engineers and scientists working in this field.
Contents lists available at ScienceDirect
Microelectronics Reliability journal homepage: www.elsevier.com/locate/mr
Guest Editorial
Power electronics packaging Katsuaki Suganuma a, Jenn-Ming Song b, Yi-Shao Lai c a b c
Institute of Science and Industrial Research, Osaka University, Japan Department of Materials Science and Engineering, National Chung Hsing University, Taiwan Advanced Semiconductor Engineering, Inc., Taiwan
Power electronics plays one of the key roles in the generation-storagedistribution conversion cycle of the electric energy that contributes to the development of the sustainable world. New integration technology for power devices has been rapidly developed to fulfill the demands for high power density, high operation temperature and improved reliability at the same time of system miniaturizations. Present-day technologies and materials are unable to deal with the emerging problems. There are high expectations for wide band gap (WBG) power semiconductors, such as SiC and GaN devices, because they can be operated in extreme conditions where silicon power devices cannot work anymore — in environments over 200 °C, for example. Bringing out the full potential of WBG power devices requires completely new approaches covering all relevant technologies extending from structural design, electrical design, and packaging. With respect to packaging technology, innovations in materials, manufacturing techniques and reliability evaluation are inevitable. The paper included is divided into four groups, interconnection materials, damaging mechanism of solder interconnects, interface design for electric/thermal contact, and Packaging design and performance. Nano-Ag sinter joining, which is one of the most emerging materials for die-attach especially for high power applications, was reported by the first paper on wide band gap devices by X. Li and the second paper on power laser by Y. Mei. X. Li studied high temperature stability of nano-Ag sintered joints of Cu and revealed the excellent stability up to 250 °C to 960 h in vacuum while serious strength degradation occurred after aging at 250 °C only for 72 h in air. Oxidation of Cu has a key to maintain the interface integrity. Y. Mei studied on a pulse reliability investigation of high power single emitter laser modules with nano-Ag paste. Y. Mei compared the life time of a laser diode die-attached with nano-Ag sinter joining with In and Au–Sn solderings by experiment aided with FEM. He provided a semi-empirical model based on Arrhenius relationship that is established to provide relative reliability assessments for laser modules. R. Mahmudi reported on creep behavior of Zn–4Al–3Mg–xSn alloys tested by impression technique and found that increasing Sn content of alloys increased creep rate, which can be attributed to the soft Sn-rich phase and lack of hard Mg–Zn particles. Y. H. Chen reported on a new Al–Cu intermetallic metallization for soldering and identified the reaction phases. Damaging mechanism of solder interconnects were reported by two papers, Numbers 5 and 6. T. Kadoguchi reported on electromigration at the interface between Sn–Cu and Ni–P plating at elevated temperature and pointed out that electromigration accelerates the diffusion of Ni in E-mail addresses: [email protected] (K. Suganuma), samsong@ nchu.edu.tw (J.-M. Song), [email protected] (Y.-S. Lai).
http://dx.doi.org/10.1016/j.microrel.2015.11.014 0026-2714/© 2015 Published by Elsevier Ltd.
the Ni–P plating at the cathode, which enhances the growth of a Ni depleted zone while the Ni diffusion at the anode side is depressed. P. Rajaguru proposed a proposed time dependent damage indicator model for a die-attach structure soldered with Sn–3.5Ag under irregular temperature change. In the part of interface design for electric/thermal contact, three papers are involved from number 7 to 9. M. Fujino reported on the bumpshaped vertically aligned multi-walled carbon nanotubes bonded to a Au substrate by a surface activated bonding. They found that Ar fast atom bombardment for 1200 s improves the interconnect resistance by 1/1000 of the original resistance. J. W. Yang proposed a unique method to increase orhmic contact performance by depositing Al2O3 nanoparticles on AlGaN/GaN before Au metallization which is attributed to the suppression of excess reaction between the metallization and the substrate during annealing process. Y. Xuan reported on graphene mixed with epoxy as thermal interface material. They found that the smallest thermal contact resistance is achieved with 6 wt% graphene primarily influenced by the hardness of the composite. In the 4th part of the current special issue, packaging design and performance, four papers are included from numbers 10 to 13. G. Q. Lu studied on the design procedure and experimental verification of a thermal characterization system for IGBT modules. They found nano-Ag sinter die-attach gives 12 % lower Zth (transient thermal impedance) than SAC solder. C.-C. Lee proposed an embedded IGBT module for the reduction of inductance at the same time of attractive miniaturization. M.-Y. Tsai reported on solution for cracking problem of a direct-plated-copper aluminum nitride substrate with excellent thermal conductivity. They employed warpage measurement combined with FEM analysis. Finally, J. Li studied on the failure of several types of Si IGBT configurations on a DBC substrate under overcurrent. The configurations are the conventional Al wire bonding, flexible PCB interconnect and DBC supported flexible PCB. Thus, the current special issue is intended to stretch our steps into the new world of interconnect technology especially for the extreme environmental conditions for power devices including Si and wide band gap semiconductors. It is our pleasure that many papers have been submitted to this issue. Among them, 13 excellent papers are involved in the current issue. As briefly summarized above, they are ranging from the individual interconnection materials such as solders and sinter joining, wire bonding, interconnect performance, and reliability issues such as thermal exposure/cycling, and electromigration. The editors are hoping that all those new findings in papers will provide some new insights and ideas to the engineers and scientists working in this field.