Interlayer materials to reduce transient liquid phase bonding time

Sunghyun Sohn(손성현),Namhyun Kang(강남현) 대한용접·접합학회 2019 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2019 No.11

Strategies to Reduce Transient Liquid Phase Bonding Time for the Die Attach of Power Semiconductors

Sunghyun Sohn,Daewon Kim,Hongpyo Kim,Namhyun Kang 대한용접·접합학회 2020 대한용접·접합학회지 Vol.38 No.2

Wide band gap (WBG) power semiconductors have superior properties and accordingly demand for WBG semiconductors has grown recently in various fields, including national defense applications. Since WBG power semiconductors operate in high temperature conditions, interconnects with high temperature reliability are required. Transient liquid phase bonding (TLPB) is emerging as one of the die attach technologies for WBG power semiconductors. However, TLPB has drawbacks, such as long bonding times and void formation. We investigated various methods to address the shortcomings of TLPB, and determined TLPB time can be reduced and void formation can be suppressed through the development of process and interlayer design. This study describes the principles, strengths and weaknesses of each process and interlayer material design.

Interlayer Material Design Reducing Transient Liquid Phase Bonding Time

Sunghyun Sohn,Byungrok Moon,Junghoon Lee,Namhyun Kang,Young Hoon Moon 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.2

Power semiconductors require a large bonding area for die attachment. For this purpose, transient liquid phase bonding(TLPB) was applied using fabricated interlayers, namely Sn–3Cu and Sn–10Cu, to study the intermetallic compound (IMC)formation, and the results were compared with those obtained with a pure-Sn interlayer. The Sn–3Cu and Sn–10Cu interlayersexhibited primary IMC fraction of 0.06 and 0.24, respectively, before the TLPB. For a Cu/interlayer/Cu sandwich structure,the TLPB was applied at 250 °C over various time periods (1–4 h). A reduction in the bonding time was more signifi cant fora Sn–10Cu interlayer with a larger amount of primary IMCs than for the Sn–3Cu interlayer. The time exponent of the IMCfraction with respect to the bonding time was approximately 0.3 for all interlayers. This implies that the IMC growth mechanismis governed by a liquid channel or wet grain boundary diff usion. The nearly constant fraction and increasing size of theprimary IMCs produced during the TLPB indicate that the primary IMCs coalesced during this process. The primary IMCspreferentially coalesced with the interface IMCs produced during the TLPB when they had the same crystalline orientation.

Interlayer 설계와 그에 따른 천이액상접합 특성평가

손성현(Sunghyun Sohn),강남현(Namhyun Kang) 대한용접·접합학회 2018 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2018 No.11

기술수요 융합형 국방 핵심기술 과제기획 방안

손성현(Sunghyun Sohn) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.8

첨단과학기술군 육성과 국방 연구개발 역량 강화를 위해 다양한 국방기술 연구개발사업이 수행되고 있다. 그중 핵심기술 연구개발사업은 향후 소요군에서 필요한 무기체계와 가장 밀접하게 연관이 있는 사업으로 사업의 목적과 예산의 규모를 고려할 때 중요한 사업이라 할 수 있다. 하지만 기술로드맵에서 식별된 핵심기술과 선행연구에서 식별된 핵심기술이 일치하지 않아 무기체계 연구개발사업에 지연이 발생하여 무기체계의 적기 전력화에 지장을 주는 요소가 식별되었다. 또한, 상향식 과제기획의 경우 2022년 공모된 418개의 과제 중 공모대상기술에 부합하지 않는 공모과제수가 293건이었다. 이는 기술로드맵에서 도출한 공모대상기술이 주요 과제제기기관인 산학연의 기술수요를 제대로 반영하지 않고 있음을 나타낸다. 핵심기술 연구개발사업 예산의 경우, 기존 핵심기술 과제기획 절차에 따라 미기획 과제에 대한 예산 요구를 수행하여 예산의 불확실성을 내포하고 있다. 이처럼 현재 핵심기술 연구개발사업은 무기체계 적용성과 예산의 체계성 측면에서 개선할 필요가 있다. 이를 위해, 국가연구개발사업에서 활용되고 있는 기술수요조사를 현 핵심기술 사업기획 체계에 접목하여 기술 로드맵을 고도화하는 기술수요 융합형 핵심기술 과제기획 방안을 제시하였다. 이에 따라 기존 기술 로드맵에서는 식별하지 못하였던 핵심기술을 식별하고 로드맵에 반영하여 무기체계 적용성을 제고할 수 있고, 기존 상‧ 하향식 과제기획에서 발생하였던 미기획 과제를 방지함으로써 예산 요구의 체계성을 확보할 수 있을 것으로 판단된다. Various research and development (R&D) projects for defense technology are being carried out to foster science and technology in the army and strengthen defense R&D capabilities. A core technology R&D project is a project most that is closely related to a weapons system that is needed in the future and can be said to be an important project when considering the purpose of the project and the size of the budget. However, the core technology identified in the roadmap and the core technology identified in prior research do not match, resulting in delays in a weapons system R&D project and a bad effect that has hindered the timely deployment of the weapon system. In addition, in the case of bottom-up project planning, among 418 projects submitted for public offering in 2022, 293 projects did not conform to the technology for proposal. This indicates that the competition target technology derived from the roadmap does not properly reflect the technology demand of industry, academia, and research institutes, which are major task-proposing organizations. In the case of the budget for a core technology R&D project, budget demand for unplanned tasks is carried out in accordance with the current core-technology task-planning procedure, implying budget uncertainty. As such, the current core technology R&D project needs to be improved in terms of the application of a weapons system and systematicity of the budget. Therefore, task planning for convergence of technology demand is proposed to upgrade the technology roadmap by combining the technology demand survey used in national R&D projects with the current core technology planning system. As a result, key technology that was not identified in the current technology roadmap can be identified and reflected in the roadmap to improve the applicability of a weapons system. In addition, the occurrence of unplanned tasks in the current planning process was prevented to improve the systematicity of the core technology R&D budget.

Cohort-based evacuation time estimation using TSIS-CORSIM

Park, Sunghyun,Sohn, Seokwoo,Jae, Moosung Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6

Evacuation Time Estimate (ETE) can provide decision-makers with a likelihood to implement evacuation of a population with radiation exposure risk by a nuclear power plant. Thus, the ETE is essential for developing an emergency response preparedness. However, studies on ETE have not been conducted adequately in Korea to date. In this study, different cohorts were selected based on assumptions. Existing local data were collected to construct a multi-model network by TSIS-CORSIM code. Furthermore, several links were aggregated to make simple calculations, and post-processing was conducted for dealing with the stochastic property of TSIS-CORSIM. The average speed of each cohort was calculated by the link aggregation and post-processing, and the evacuation time was estimated. As a result, the average cohort-based evacuation time was estimated as 2.4-6.8 h, and the average clearance time from ten simulations in 26 km was calculated as 27.3 h. Through this study, uncertainty factors to ETE results, such as classifying cohorts, degree of model complexity, traffic volume outside of the network, were identified. Various studies related to these factors will be needed to improve ETE's methodology and obtain the reliability of ETE results.

AutoDyn7 프로그램의 접촉모듈 개발

임성현(Sunghyun Lim),손정현(Jeonghyun Sohn),김광석(Kwangsuk Kim),유완석(Wansuk Yoo) 한국자동차공학회 2001 한국 자동차공학회논문집 Vol.9 No.6

In multibody dynamic analysis including contact and impact, there are two major analysis methods, i.e., piecewise analysis and continuous analysis. Modeling or contact phenomena is mainly classified with a Kelvin-Voigt model or a model of Hertz contact model. In this paper, a contact module for AutoDyn7 program was developed and implemented. Both the Kelvin-Voigt model and a model or Hertz contact law were developed. The process or this module is composed of contact distinction and the contact force calculation. Two examples were verified and compared to the commercial program DADS.<br/>

Reliable low-energy group formation for infrastructure-less public safety networks

Seong, Seonik,Sohn, Illsoo,Choi, Sunghyun,Lee, Kwang Bok Springer (Biomed Central Ltd.) 2016 Eurasip Journal on Wireless Communications and Net Vol.2016 No.-

<P>In this paper, we study an infrastructure-less public safety network (IPSN) where energy efficiency and reliability are critical requirements in the absence of cellular infrastructure, i.e., base stations and wired backbone lines. We formulate the IPSN group formation as a clustering problem. A subset of user equipments (UEs), called group owners (GOs), are chosen to serve as virtual base stations, and each non-GO UE, referred to as group member, is associated with a GO as its member. We propose a novel clustering algorithm in the framework of affinity propagation, which is a state-of-the-art message-passing technique with a graphical model approach developed in the machine learning field. Unlike conventional clustering approaches, the proposed clustering algorithm minimizes the total energy consumption while guaranteeing link reliability by adjusting the number of GOs. Simulation results verify that the IPSN optimized by the proposed clustering algorithm reduces the total energy consumption of the network by up to 31% compared to the conventional clustering approaches.</P>

Distributed Synchronization Algorithm for Infrastructure-less Public Safety Networks

Seong, Seonik,Sohn, Illsoo,Choi, Sunghyun,Lee, Kwang Bok The Korean Institute of Communications and Informa 2018 Journal of communications and networks Vol.20 No.3

In this paper, we propose a distributed synchronization algorithm for infrastructure-less public safety networks. The proposed algorithm aims to minimize the number of out-of-sync user equipments (UEs) by efficiently forming synchronization groups and selecting synchronization reference (SyncRef) UEs in a distributed manner. For the purpose, we introduce a novel affinity propagation technique which enables an autonomous decision at each UE based on local message-passing among neighboring UEs. Our simulation results show that the proposed algorithm reduces the number of out-of-sync UEs by up to 31% compared to the conventional scan-and-select strategy.

구조물 안전 진단 센서용 무선 전력 전송 구현을 위한 RF 기반 915MHz 대역 전력 증폭기 설계

정승환(Seunghwan Jung),손훈(Hoon Sohn),한민석(Minseok Han),이경학(Kyunghak Lee),황성현(Sunghyun Hwang) 한국통신학회 2015 한국통신학회 학술대회논문집 Vol.2015 No.06