- document
-
Hu, D. (author), Cui, Z. (author), Fan, J. (author), Fan, X. (author), Zhang, Kouchi (author)A molecular dynamics (MD) simulation was performed on the coalescence kinetics and mechanical behavior of the pressure-assisted Cu nanoparticles (NPs) sintering at low temperature. To investigate the effects of sintering pressure and temperature on the coalescence of the nanoparticles, sintering simulations of two halve Cu NPs were conducted at...journal article 2020
- document
-
Tang, H. (author), Sacco, L.N. (author), Vollebregt, S. (author), Ye, H. (author), Fan, Xuejun (author), Zhang, Kouchi (author)2D and nanostructured metal sulfide materials are promising in the advancement of several gas sensing applications due to the abundant choice of materials with easily tunable electronic, optical, physical, and chemical properties. These applications are particularly attractive for gas sensing in environmental monitoring and breath analysis....review 2020
- document
-
Ibrahim, Mesfin Seid (author), Fan, Jiajie (author), Yung, Winco K.C. (author), Prisacaru, Alexandru (author), van Driel, W.D. (author), Fan, X. (author), Zhang, Kouchi (author)Light-emitting diodes (LEDs) are among the key innovations that have revolutionized the lighting industry, due to their versatility in applications, higher reliability, longer lifetime, and higher efficiency compared with other light sources. The demand for increased lifetime and higher reliability has attracted a significant number of...review 2020
- document
-
Zhang, H. (author), Liu, Y. (author), Wang, Lingen (author), Sun, Fenglian (author), Fan, Xuejun (author), Zhang, Kouchi (author)The nanoindentation test was conducted in this paper to investigate the indentation hardness, plasticity and initial creep properties of pressure sintered nanosilver joint at various test temperatures. The effects of strain rate on the indentation hardness were first investigated. Then yield stress of nanosilver sintered joint was studied in...journal article 2019
- document
-
Sun, B. (author), Fan, J. (author), Fan, Xuejun (author), Zhang, Kouchi (author), Zhang, Guohao (author)In this paper, a physics of failure-based prediction method is combined with statistical models to consider the impact of current crowding and current droop effects on the reliability of LED arrays. Electronic-thermal models of LEDs are utilized to obtain the operation conditions under the influences of current crowding and current droop. A...journal article 2019
- document
-
Zhang, H. (author), Liu, Y. (author), Wang, Lingen (author), Sun, Fenglian (author), Fan, Jiajie (author), Placette, Mark D. (author), Fan, Xuejun (author), Zhang, Kouchi (author)Modern power electronics has the increased demands in current density and high-temperature reliability. However, these performance factors are limited due to the die attach materials used to affix power dies microchips to electric circuitry. Although several die attach materials and methods exist, nanosilver sintering technology has received...journal article 2019
- document
-
Liu, Y. (author), Zhang, H. (author), Wang, Lingen (author), Fan, Xuejun (author), Zhang, Kouchi (author), Sun, Fenglian (author)Purpose: Crack and stress distribution on dies are key issues for the pressure-assisted sintering bonding of power modules. The purpose of this research is to build a relationship among stress distributions, sintering sequences and sintering pressures during the sintering processes. Design/methodology/approach: Three sintering sequences, S(a)...journal article 2019
- document
-
Fan, J. (author), Wang, Zhen (author), Zhang, Xunwei (author), Deng, Zentao (author), Fan, Xuejun (author), Zhang, Kouchi (author)In a high-power white light emitting diode (LED) package, the phosphor/silicone composite is typically used for photometric and colorimetric conversions, ultimately producing the white light. However, the phosphor/silicone composite is always exposed under harsh environments with high temperature, high blue light irradiation and high moisture...journal article 2019
- document
-
Chen, Wei (author), Fan, J. (author), Qian, Cheng (author), Pu, Bin (author), Fan, Xuejun (author), Zhang, Kouchi (author)The inherent luminous characteristics and stability of LED packages during the operation period are highly dependent on their junction temperatures and driving currents. In this paper, the luminous flux of LED packages operated under a wide range of driving currents and junction temperatures are investigated to develop a luminous flux...journal article 2019
- document
-
Yang, Ning (author), Yang, Daoguo (author), Zhang, Kouchi (author), Chen, Liangbiao (author), Liu, Dongjing (author), Cai, Miao (author), Fan, Xuejun (author)The effects of graphene stacking are investigated by comparing the results of methane adsorption energy, electronic performance, and the doping feasibility of five dopants (i.e., B, N, Al, Si, and P) via first-principles theory. Both zigzag and armchair graphenes are considered. It is found that the zigzag graphene with Bernal stacking has...journal article 2018
- document
-
Liu, Yang (author), Zhang, H. (author), Wang, Lingen (author), Fan, Xuejun (author), Zhang, Kouchi (author), Sun, Fenglian (author)The microstructure, thickness, porosity, and shear performance of the silver (Ag) sintering layers under different sintering pressures were investigated. Experimental results demonstrated that the thickness and the porosity of the sintering layer decreased when the sintering pressure varied from 5 MPa to 30 MPa. This densification phenomenon...journal article 2018
- document
-
Zhang, H. (author), Liu, Yang (author), Wang, Lingen (author), Fan, Jiajie (author), Fan, Xuejun (author), Sun, Fenglian (author), Zhang, Kouchi (author)High reliable packaging materials are needed for electronics when they work at harsh environments. Among which, the nanosilver material has been widely studied and applied in power electronics due to its low processing temperature and high reliability. This paper investigates the bonding properties of nanosilver sintered hermetic cavity. There...journal article 2018
- document
-
Sun, Bo (author), Fan, Xuejun (author), van Driel, W.D. (author), Cui, Chengqiang (author), Zhang, Kouchi (author)In this study, we present a general methodology that combines the reliability theory with physics of failure for reliability prediction of an LED driver. More specifically, an integrated LED lamp, which includes an LED light source with statistical distribution of luminous flux, and a driver with a few critical components, is considered. The...journal article 2018
- document
-
Qian, C. (author), Mirza Gheytaghi, Amir (author), Fan, J. (author), Tang, H. (author), Sun, B. (author), Ye, H. (author), Zhang, Kouchi (author)As an increasing attention towards sustainable development of energy and environment, the power electronics (PEs) are gaining more and more attraction on various energy systems. The insulated gate bipolar transistor (IGBT), as one of the PEs with numerous advantages and potentials for development of higher voltage and current ratings, has been...journal article 2018
- document
-
Cui, Z. (author), Chen, Xianping (author), Fan, Xuejun (author), Zhang, Kouchi (author)Interfacial properties of Cu/SiO2 in semiconductor devices has continued to be the subject of challenging study for many years because of its difficulties in experimentally quantifying the critical strength of interface. In this paper, a multi-scale modeling approach is built to characterize the interfacial properties between Cu and SiO2. In...conference paper 2018
- document
-
Sun, B. (author), Fan, J. (author), Fan, Xuejun (author), Zhang, Kouchi (author)This work studies the effect of randomness of LED's lumen depreciation on reliability of the entire LED lamp. An integrated LED light bulb is selected as carrier of the proposed method. A PoF based lumen depreciation model and electronic-thermal simulations are introduced for reliability prediction. The normal distribution is used to describe...conference paper 2018
- document
-
Lu, G. (author), Fan, Xuejun (author), Fan, Jiajie (author), Zhang, Kouchi (author)Color stability is of major concern for LED-based products. Currently, much effort is done on lumen maintenance, and for color shift, no agreed method currently exists, be it from testing or from prediction side. To investigate the physics of color shift, we present experiments of each individual part failure of each individual part that are...book chapter 2018
- document
-
Sun, B (author), Fan, Xuejun (author), Zhang, Kouchi (author)This chapter investigates the reliability of the integrated LED lamps with electrolytic capacitor-less LED drivers. Firstly, the impact of the interaction between the degradations of the LED light source and the driver on the lumen depreciation is studied. The electronic-thermal simulation was carried out to obtain the history of temperatures of...book chapter 2018
- document
-
Tang, H. (author), Ye, Huai-Yu (author), Chen, Xian-Ping (author), Qian, Cheng (author), Fan, Xue-Jun (author), Zhang, Kouchi (author)In this paper, the heat transfer performance of the multi-chip (MC) LED module is investigated numerically by using a general analytical solution. The configuration of the module is optimized with genetic algorithm (GA) combined with a response surface methodology. The space between chips, the thickness of the metal core printed circuit board...journal article 2017
- document
-
Sun, B. (author), Fan, Xuejun (author), Ye, H. (author), Fan, Jiajie (author), Qian, Cheng (author), van Driel, W.D. (author), Zhang, Kouchi (author)In this paper, an integrated LED lamp with an electrolytic capacitor-free driver is considered to study the coupling effects of both LED and driver's degradations on lamp's lifetime. An electrolytic capacitor-less buck-boost driver is used. The physics of failure (PoF) based electronic thermal simulation is carried out to simulate the lamp's...journal article 2017