Article
Materials Science, Multidisciplinary
Minkyu Kang, SungJun Choi, Dongho Shin, Caroline Sunyong Lee
Summary: High-speed flash-light sintering was used to fabricate highly conductive copper-based inkjet patterns on flexible substrates for lightweight devices. A two-step sintering process resulted in patterns with high density, low resistivity, and long-term stability, showing potential for practical applications.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Review
Chemistry, Multidisciplinary
Zheng Li, Shuquan Chang, Saurabh Khuje, Shenqiang Ren
Summary: This review discusses the use of copper nanostructures as building blocks for printable ink materials to achieve high electric conductivity and stability. Copper-based flexible hybrid electronics and energy-critical devices printed by different printing techniques are reviewed for emerging applications.
Article
Nanoscience & Nanotechnology
Yue Cao, Guo-Cheng Xu, Lin Li, Hai-Rong Mao, Rui-Fen Guo, Ping Shen
Summary: Flash sintering and in situ joining of 3YSZ with metal were achieved under an electric field, leading to rapid densification. However, defects were present in the joints due to the application of a single AC or DC field. Electric field-induced Joule heating and internal electrochemical reaction were the key mechanisms for the sintering process.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Yun Mou, Yang Peng, Jiaxin Liu, Qing Wang, Zhenyu Lei, Fengshun Wu, Mingxiang Chen
Summary: An inexpensive and self-reducing Ag2O ink was designed for fabricating highly flexible printed conductors at low sintering temperature, demonstrating low electrical resistivity and good flexibility in the sintered Ag tracks. This ink provides an attractive prospect for low-temperature fabrication of high-quality flexible printed conductors.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Gui-Bing Hong, Jia-Fang Wang, Kai-Jen Chuang, Hsiu-Yueh Cheng, Kai-Chau Chang, Chih-Ming Ma
Summary: Nanotechnology is widely used in various fields and is particularly popular in the development of flexible electronic products. This study successfully synthesized copper nanoparticles with good dispersibility using an environmentally friendly chemical reduction method. The copper nanoparticles were then applied to a flexible polyethylene terephthalate substrate and showed promising results.
Article
Multidisciplinary Sciences
Sajal Chakraborty, Ho-Yeol Park, Sung Il Ahn
Summary: In this study, cost effective direct laser patterning of copper on thin polyimide substrates was achieved by controlling the focal length of the laser. The appropriate focal length was found to reduce defects on the patterned copper and surface damage of the polyimide. Different copper growth patterns were observed depending on the focal length used. The resistivity of the patterns decreased after cleaning, indicating a decrease in adhesion. A 70 μm scan gap resulted in the lowest sheet resistance and the least change in resistance after cleaning. This method showed potential for application in bioelectronics.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Electrical & Electronic
Soo Min Song, Sung Min Cho
Summary: A copper ion ink capable of screen printing and IPL sintering on PET substrates was developed, showing quick drying, excellent electrical resistivity, and good screen printability.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Chemistry, Physical
Yabing Zhang, Teng Zhang, Hongbin Shi, Qing Liu, Tao Wang
Summary: Flexible conductive copper patterns with low electric resistance, good adhesion, and high stability were successfully prepared on heat-sensitive PET substrate by combining inkjet print with Cu NPs conductive ink and ELP copper. The patterns exhibited low resistivity, excellent anti-oxidation performance, and remained adhered to the substrate even after 4000 cycles bending test.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Mingyang Zhang, Guoqiang Li, Lei Huang, Puhang Ran, Jianping Huang, Mei Yu, Hengyuan Yuqian, Jinhong Guo, Zhiyuan Liu, Xing Ma
Summary: The study introduces a PVP stabilized LM nano-ink that can be used for constructing flexible electronic devices through various fabrication strategies, including direct-writing on paper, filtration into conductive films, and laser cutting customized conductive patterns. The LM nano-ink reconciles stability and biocompatibility, providing huge potential for future implanted flexible electronics.
APPLIED MATERIALS TODAY
(2021)
Article
Materials Science, Multidisciplinary
Swami Siddharth, Yu-Bin Chen, Ming-Tsang Lee
Summary: A particle-free copper ionic solution is developed for laser-induced reductive patterning of copper microlines on a flexible substrate. The use of laser postprocessing resulted in a 39% reduction in electrical resistance and a 77% enhancement in mechanical durability of the fabricated microlines.
ADVANCED ENGINEERING MATERIALS
(2022)
Article
Materials Science, Ceramics
Shannon E. Murray, Yu-Ying Lin, Soumitra S. Sulekar, Mebatsion S. Gebre, Nicola H. Perry, Daniel P. Shoemaker
Summary: Reactive flash sintering is an effective method for densifying and synthesizing ceramic materials, but the predictive capability of the BBR model for phase transformations during the process is limited. CuO reduction and Mn(2)O(3) reduction demonstrate the challenges of predicting phase transformations due to local, stochastic current flow and localized heating. Understanding and engineering the complex thermal profile that results from these sources of inhomogeneity can be beneficial for optimizing reaction kinetics.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Po-Hsiang Chiu, Wei-Han Cheng, Ming-Tsang Lee, Kiyokazu Yasuda, Jenn-Ming Song
Summary: Copper oxide particles were used to form conductive circuits through photonic sintering, resulting in improved electrical conductivity without damaging the substrate. The addition of Cu2O and copper formate was found to decrease the electrical resistivity of the reduced copper further.
Article
Engineering, Manufacturing
Hanyu Song, Zheng Kang, Benxin Wu
Summary: Replacing metal components with metal nanocomposites reinforced by carbon nanotubes can enhance the reliability and durability of flexible electronics. Nanosecond laser pulse sintering of these nanocomposites can result in lower electrical resistivity and narrower widths compared to continuous-wave laser sintering, at a faster speed.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Materials Science, Multidisciplinary
Yu Wu, Chao Chen, Yuan Meng, Wenjie Huang, Jianfei Hu, Meng Chang, Ziwei Liu, Qunchao Zhang, Tao Jiang, Wei Wu, Xianwu Cao, Dean Shi, Tonghui Hao
Summary: This study demonstrates the use of blade-coated conductive ink on poly(ethylene terephthalate) substrate to fabricate flexible light-emitting electronic devices. The unique feature of the ink is its high-performance 3D conductive channel network with low resistance, achieved by combining carbon-based fillers and epoxy resin. The carbon-based channels in the conductive composites exhibit excellent resistance reliability and durability under bending, ultrasonic treatment, and exposure to organic solvents. Thus, this work presents a new solution for the development of high-efficiency, low-cost, large-scale production of flexible electronics.
ADVANCED ENGINEERING MATERIALS
(2022)
Article
Chemistry, Physical
Vu Binh Nam, Trinh Thi Giang, Daeho Lee
Summary: A facile method for synthesizing CuOx nanoparticles ink was presented to fabricate high-quality CuOx thin films with finely-structured Cu electrodes on polymer substrates. Laser-induced reductive sintering process was utilized to achieve low resistivity and transparent conducting panels with high transmittance. Superior electromechanical stability of Cu electrodes and long-term oxidation resistance were confirmed, demonstrating the potential application of Cu-based flexible transparent touchscreen panels.
APPLIED SURFACE SCIENCE
(2021)
Article
Green & Sustainable Science & Technology
Yeon-Taek Hwang, Hak-Sung Kim
Summary: The UV-IR assisted intense pulsed light (IPL) process was found to enhance the reduction efficiency of graphene oxide (GO) compared to other methods, without causing damage to the GO sheet. By optimizing the conditions of the UV-IR assisted IPL, graphene films were successfully reduced and characterized using various spectroscopic techniques. The reduced GO based electrode showed promising performance for use in electrical double layer capacitors when tested using a three electrode electrochemical method.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2022)
Article
Green & Sustainable Science & Technology
Jeong-Beom Nam, Yong-Rae Jang, Yeon-Taek Hwang, Hyun-Ho Kim, Il-Hyoung Jung, Hak-Sung Kim
Summary: Silver-coated copper paste sintered on silicon heterojunction solar cells via intense pulsed light (IPL) can improve electrode efficiency, increase open circuit voltage, and has been confirmed to be reliable through long-term testing.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
Jong-Whi Park, Chang-Jin Moon, Young-Min Ju, Yong-Rae Jang, Simon S. Park, Hak-Sung Kim
Summary: This study demonstrates the use of IPL for reducing GO to form a flexible ReRAM with high electrical performance. Optimizing the irradiation conditions leads to high retention and switching characteristics, with a depth gradient reduced GO layer. The ReRAM shows WORM characteristics, high on/off ratio, long retention time, and excellent mechanical endurance when fabricated on a flexible substrate.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Engineering, Multidisciplinary
Hui-Jin Um, Yeon-Taek Hwang, Il-Joon Bae, Hak-Sung Kim
Summary: In this study, an underbody shield made of carbon fiber reinforced thermoplastic composites was designed and manufactured to protect the lithium batteries in electric vehicles from impact damage. Through finite element analysis and optimization, the designed underbody shield successfully protected the battery from deformation and leakage during a vehicle crash test with a concrete obstacle.
COMPOSITES PART B-ENGINEERING
(2022)
Article
Engineering, Electrical & Electronic
Jeong-Hyeon Baek, Dong-Woon Park, Gyung-Hwan Oh, Dong -Ok Kawk, Simon S. Park, Hak-Sung Kim
Summary: In this study, the cure shrinkage, internal strain development, and viscoelastic properties of epoxy molding compound (EMC) for semiconductor packaging were investigated using fiber Bragg grating (FBG) and dielectric sensors. The warpage of EMC-aluminum bi-layer strip was measured using digital image correlation (DIC). The results confirmed the importance of considering the cure shrinkage of EMC in predicting the warpage behavior of semiconductors.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Chang-Jin Moon, Jong-Whi Park, Yong-Rae Jang, Young-Min Ju, Hak-Sung Kim
Summary: This study achieved the realization of molybdenum (Mo) patterns through intense pulsed light (IPL) irradiation process at room temperature, eliminating the need for vacuum deposition. By optimizing the IPL irradiation process, the low electrical conductivity resulting from oxide film on the surface of Mo nanoparticles was improved. The microstructure of the Mo pattern and its interface with the IGZO layer were investigated.
Article
Green & Sustainable Science & Technology
Dong-Woon Park, Myeong-Hyeon Yu, Do-Hyung Kim, Dong-Min Jang, Jin-Woo Jang, Seung-Yeong Lee, Hak-Sung Kim
Summary: In this study, the influence of pad design on assembly defect rate was investigated using computational fluid dynamics (CFD) simulation. The restoring force and moment acting on the chip resistor were calculated using CFD simulation considering the fluidic forces of the molten lead-free solder paste.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2023)
Article
Robotics
Woolim Hong, Namita Anil Kumar, Shawanee Patrick, Hui-Jin Um, Heon-Su Kim, Hak-Sung Kim, Pilwon Hur
Summary: The toe joint plays a critical role in human ambulation and using custom-designed prosthetic feet with toe joints can lead to a more natural and symmetric gait. The curved-toe foot showed greater toe flexion and improved stability and symmetry in walking compared to the flat-toe foot.
IEEE ROBOTICS AND AUTOMATION LETTERS
(2022)
Article
Engineering, Multidisciplinary
Myeong-Hyeon Yu, Ji-Seok Lee, Hak-Sung Kim
Summary: Addressable conducting network (ACN) was used for damage sensing and self-healing of continuous carbon fiber reinforced nylon composite (CFRP). Machine learning was employed to accurately sense damage and generate local heating for self-healing. Self-healing conditions were determined using artificial neural network (ANN) based machine learning, achieving a healing efficiency of 98%.
STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL
(2023)
Article
Green & Sustainable Science & Technology
Young-Min Ju, Jong-Whi Park, Yong-Rae Jang, Simon S. Park, Hak-Sung Kim
Summary: In this work, the silver nanowires (AgNWs) were welded and embedded into polyethylene terephthalate substrate under room temperature and ambient conditions by an intense pulsed light (IPL) irradiation with applying mechanical roll-pressing simultaneously. The AgNW flexible transparent conductive electrodes (FTCEs) by IPL with the simultaneous mechanical roll-pressing showed significant improvements in electrical conductivity, optical properties, and surface roughness compared to the unwelded AgNW FTCEs.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2023)
Article
Green & Sustainable Science & Technology
Sang-Il Kim, Dug-Joong Kim, Do-Hyung Kim, Dong-Min Jang, Jin-Woo Jang, Seung-Yeong Lee, Hak-Sung Kim
Summary: In this study, a simulation model was used to predict the corrosion lifetime of PCBs in marine atmospheric environments, and the validity of the model was verified through a salt spray corrosion acceleration test. Finally, corrosion life equations for PCBs based on geometrical and environmental factors were proposed.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2023)
Article
Engineering, Multidisciplinary
Heon-Su Kim, Dong-Woon Park, Sang-Il Kim, Gyung-Hwan Oh, Hak-Sung Kim
Summary: This study presents a non-destructive evaluation method using a CNN-based THz signal processing to distinguish overlapping signals from micro-defects in GFRP composites. Theoretical models were devised to describe the propagation of the THz signal and its interaction with the micro-defects. THz signals were transformed into 2D spectrograms and used to train a CNN deep learning model for classifying the size and thickness of the defects. The CNN model achieved a 95% accuracy in differentiating micro-defects thinner than 20 μm.
COMPOSITES PART B-ENGINEERING
(2023)
Article
Mechanics
Dug-Joong Kim, Gyu-Won Kim, Jeong-hyeon Baek, Byeunggun Nam, Hak-Sung Kim
Summary: A novel deep neural network was proposed for predicting the mechanical behavior of plain carbon fabric reinforced woven composites. The network was trained using a pre-simulated stress-strain curve database based on yarn structures and material properties. Micro-mechanics-based multi-scale analyses were conducted for progressive damage analysis, and the network was optimized using the Hyperband algorithm. The predicted mechanical behavior of the composites was validated through mechanical tests.
COMPOSITE STRUCTURES
(2023)
Article
Engineering, Manufacturing
Yeon-Taek Hwang, Hui-Jin Um, Hak-Sung Kim
Summary: In this study, the in-plane shear deformation of woven fabric composites during the forming process was predicted using finite element analysis. A multi-scale modeling approach was used to predict mechanical properties and damage progression based on a micro-scale fiber/matrix failure criterion using the strain invariant failure theory.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2023)
Article
Engineering, Electrical & Electronic
Yong-Rae Jang, Sang-Jun Park, Jeong-Hyeon Baek, Tae-Hwa Kim, Hak-Sung Kim
Summary: This study predicted the thermal shock life cycle of a wide bandgap power module using finite element analysis. The analysis considered the thermal fatigue/creep deformation of Ag sintered joints and the viscoelastic properties of epoxy molding compounds under periodic thermal shock conditions. Creep tests and stress relaxation tests were conducted to obtain the creep properties and viscoelastic properties of the materials. The failure life cycle of the Ag sintered joints was calculated and confirmed through thermal shock tests.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
