Papers by Author: Jian Hua Zhang

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Authors: Long Long Chen, Xi Feng Li, Ji Feng Shi, Hao Zhang, Chun Ya Li, Jian Hua Zhang
Abstract: Amorphous InGaZnO (a-IGZO) films are deposited on the glass substrate by RF sputtering and the influence of wet etching of a-IGZO films, etching rate, over etching features and TFT structure chose are investigated. The results show that Oxalic acid is best chose for IGZO film etching for side etching is about 0.1um , etching rate is 7.42 A/s which is easy to control and taper angle is acute. The traditional G-I-D type structure has been confirmed is not fit for the condition where the IGZO based TFT manufacture. G-D-I structure is tested and can be used in the TFT array manufacture.
Authors: Qing Hua Li, Jian Hua Zhang
Abstract: Isotropic Conductive Adhesives (ICAs) were prepared using epoxy resin as matrix, latent curing agent as hardener, and silver particles as the conducting filler. The effects of nano-fillers (SiO2 nano-particles and carbon nanotubes) on the conductivity, adhension strength and reliability of ICAs were investigated experimentally in this paper. The results showed that these two nano fillers can improve both the conductivity and adhesion strength of ICAs, which maybe attributed to the nano-particles forming physico-chemical bonds with epoxy resin. These physico-chemical bonds increase the contact area and then minish the interspace of Ag particles, so it reduces electrical resistance and enables a high current flow. And the increasing contact area will improve the contact strength between Ag particles and epoxy resin. Under the reliability testing with the high temperature and high humidity (85°C/85RH), the SiO2 nano-particles can improve the reliability of ICAs apparently, while carbon nanotubes can not. This is because insulating material can prevent silver migration.
Authors: Chun Ya Li, Xi Feng Li, Long Long Chen, Ji Feng Shi, Jian Hua Zhang
Abstract: Under different growth conditions, silicon nitride (SiNx) thin films were deposited successfully on Si(100) substrates and glass substrates by plasma enhanced chemical vapor deposition (PECVD). The thickness, refractive index and growth rate of the thin films were tested by ellipsometer. The surface morphologies of the thin films were investigated using atomic force microscope (AFM). The average transmittance in the visible region was over 90%.
Authors: Chun Ya Li, Xi Feng Li, Long Long Chen, Ji Feng Shi, Jian Hua Zhang
Abstract: Under different growth conditions, silicon Oxide (SiOx) thin films were deposited successfully on Si (100) substrates and glass substrates by plasma enhanced chemical vapor deposition (PECVD). The thickness, refractive index and growth rate of the thin films were tested by ellipsometer. The effects of deposition temperature on the structure and properties of SiOx films were studied using X ray diffraction (XRD), X ray photoelectron spectroscopy (XPS) and UV-Visible spectroscopy. The results show that the SiOx films were amorphous at different deposition temperature. The peaks of Si2p and O1s shifted to higher binding energy with temperature increasing. The SiOx films had high transmissivity at the range of 400-900nm. By analyzing the observation and data, the influence of deposition parameters on the electrical properties and interface characteristics of SiOx thin film prepared by PECVD is systematically discussed. At last, SiOx thin film with excellent electrical properties and good interface characteristic is prepared under the relatively optimum parameters.
Authors: Jin Song Zhang, Jian Hua Zhang
Abstract: With the ban of Sn-Pb alloys coated on Cu leads in electronic devices, the electronic packaging industry uses Pb-free Sn alloys as the coating materials. This replacement meets a widely concern that Pb-free Sn alloys have a stronger propensity to grow whiskers on the surface of the coating. The experimental samples have been plated a pure Sn coating on Cu leads by an industrial plating process before the accelerated tests. The study executed three different environment conditions to estimate whiskers growth on the Sn coating of Cu leads. They were Room Temperature/Humidity Storage (RS), High Temperature/Humidity Storage (TH) and Temperature Cycling (TC). No whisker had been found in the samples during the RS tests since this environment condition had not destroyed the surface continuity to promote whiskers grow out of the Sn coating. In the TH tests, the moisture degraded the coating surface to produce the electrochemical corrosion on some local areas. Sn whiskers were easy prone to grow from the corroded areas on the coating surface with a high rate. In the TC tests, Sn whiskers grew from the cracks on the coating surface with a high density based on the mechanism of the thermal fatigue. The alternating stress in the coating surface induced by the temperature fluctuation tore the Sn oxide grains to form cracks and provide a growth path for Sn whiskers on the coating surface.
Authors: Jin Song Zhang, Jian Hua Zhang
Abstract: Sn whiskers can grow spontaneously on the surface in Sn alloy coatings. This paper focused on the mechanism of whisker growth on the pure Sn coating to Cu leads in electronic components. After the rack plating process the pure Sn coating was annealed at 150°C for one hour and measured about 10mm in thickness. Then samples endured the high temperature/humidity storage tests (60°C and 87%RH) from 1 month to 6 months. The experimental results revealed that Sn whiskers were prone to grow from the surface with local corrosion in the Sn coating. This was the high temperature/humidity storage provided much moisture to cause an electrochemistry corrosion between Sn and H2O. The excess formation of SnO2 had a large molar volume comparing to Sn and this generated a high inner stress in the corroded areas to shear the coating surface producing the defects. The compressive stress deriving from the formation of Cu-Sn intermetallic compounds drove Sn whiskers initially grew from the corroded areas.
Authors: Lang Wang, Jian Hua Zhang, Lian Qiao Yang
Abstract: In this paper, the process parameters of graphene during fabrication and transfer are investigated. Cu is utilized as the substrate and chemical vapor deposition are used to obtain graphene. The results show that, the surface condition of the Cu substrate tends to be worse than as-received after a relatively higher temperature (1035°C) annealing and growth process, which lead to bad graphene quality. In addition, pre-treatment of Cu substrate by acetic acid is helpful to reduce the nucleation sites. Reflow process before PMMA etching is an effective method to eliminate the wrinkles formed during transfer. High-quality graphene for optoelectronic applications were obtained based on the optimized fabrication and transfer process.
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