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RISS 인기검색어
- 검색키워드
- 저자 : Hang-ling Hu (검색결과 6 건)
- 무료
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Hang-ling Hu,Li-dong He 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5
The serious vibration of rotors around the critical speed is a problem in rotor systems. To overcome this problem, a single-span twodisk rotor bench was built to simulate the starting process of a rotor. A new Rotor dynamic vibration absorber (RDVA) was designed and installed in the middle of the rotor. A on-off control method based on speed was applied to control the on-off position of the electromagnet in RDVA. Therefore, the natural frequencies between two selected values could be changed. The principles for the vibration control of the rotor system were studied. The vibration suppression performance of an RDVA is a function of its location. The location of the RDVA is subject to several constraints due to the compact structure of the rotor system. As a result, RDVA cannot always be installed at the optimal location of vibration suppression. Accordingly, a study was performed to observe the effect of RDVA location on the vibration suppression performance. Results showed that installing RDVA with on-off control between the two disks not only suppressed the violent vibrations of the rotor at critical speed during the starting process but also avoided the two resonance peaks generated by the traditional absorber. RDVA maintained the vibration of the rotor at a low level in the entire speed range. Furthermore, the vibrations of the rotor system decreased by 20 % when RDVA was installed near the rotor support.
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Hua Hu,Ruoxun Zhang,Yunwen Wu,Huiqin Ling,Tao Hang,Ming Li 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.1
As the size of interconnect technology in integrated circuits keeps minimizing, the electrical resistivity and signal transmission delay become increasingly serious. The monocrystalline materials can meet the requirements of miniaturization and high-speed interconnection, which is a proper solution of these problems. Hence, we fabricated large monocrystalline Cu cones with (111) orientation using a linear sweep voltammetry electroplating method for the first time. It was found that phosphorus could induce texturization of polycrystals at a certain potential. The grains with uniform orientation grown into single crystals through the oriented attachment growth mechanism. The screw dislocations produced during oriented attachment led to crystal spiral growth, developing into large monocrystalline cones. This work is expected for application in copper interconnect technology in the future.
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Sub-surface Damage of Ultra-Thin Monocrystalline Silicon Wafer Induced by Dry Polishing
Xundi Zhang,Chenlin Yang,Yumei Zhang,Anmin Hu,Ming Li,Liming Gao,Huiqin Ling,Tao Hang 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.4
Ultra-thin wafer fabrication has become a hot spot in recent years with the growing demand for small size and high performance electronic devices. However, far less research focused on the damage behavior in ultra-thin wafer. In this work, 300 mm diameter silicon wafer was thinned to 6 µm thick by grinding plus ultra-precision dry polishing. The damage behavior before and after the dry polishing was discussed. Mechanical and surface analysis showed that the dry polishing process can help improve the strength and surface uniformity of ultra-thin wafer by removing high pressure phase and micro cracks. Series of nano beam diffraction patterns revealed the stress induced by the thinning process only existed in surface. High resolution transmission electron microscopy images analyzed by geometric phase approach indicated that surface dislocations can move across the wafer and reached bottom device layers during the dry polishing, increasing the risk of electrical deterioration. The findings are of great significance to the study on process optimization of ultra-thin wafer and provide insights into the reliability of advanced electronic packaging.
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Effects of Sn Layer Orientation on the Evolution of Cu/Sn Interfaces
Menglong Sun,Zhangjian Zhao,Fengtian Hu,Anmin Hu,Ming Li,Huiqin Ling,Tao Hang 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.4
The effects of Sn layer orientation on the evolution of Cu/Sn joint interfaces were investigated. Three Sn layers possessing(112), (321) and (420) orientations were electroplated on polycrystalline Cu substrates respectively. The orientations of Snlayer preserved during reflowing at 250 °C for 10 s. After aging at 150 °C for different time, the interfacial microstructureswere observed from the cross-section and top-view. The alignment between the c-axis of Sn and Cu diffusion direction significantlysped up the Cu diffusion, leading to the thickest intermetallic compound layer formed in (112) joint. Two types ofvoids, namely, intracrystalline voids and grain islanding caused intercrystalline voids generated at Cu/Cu3Sn interfaces dueto the different interdiffusion coefficients of Cu and Sn (112) oriented Sn/Cu joint produced many more voids than (321)joint, and no voids were detected in (420) joint. Therefore, to enhance the reliability of solder joints, using (420) orientedSn as solder layer could be an efficient way.
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Yaqian Sun,Jing Wang,Xundi Zhang,Chenlin Yang,Anmin Hu,Tao Hang,Yunwen Wu,Huiqin Ling,Ming Li 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.6
At present, thermal compression bonding based on Cu and lead-free Sn based solder is often limited by high bonding temperature,which is higher than the melting point of solder (218 ℃). In this paper, we reported a low-temperature solid stateinsertion bonding method based on electroless Cu-Co-P micro-cones array. By adjusting the mass ratio of CuSO 4 ·5H 2 O andCoSO 4 ·7H 2 O, a series of Cu-Co-P micro-cones with diff erent morphologies were prepared. The Cu-Co-P micro-cones withhigher proportion of copper were sharper and denser and (111) orientation was also more. It was found that reducing theheight and density of micro-cones was conducive to achieve seamless bonding at lower temperature and force such as 170℃ and 750 gf. By optimizing the morphology of micro-cones, such as height, bottom diameter, vertex angle and density, theseamless and reliable bonding with high shear strength (39.9 MPa) could be achieved at 170 ℃ bonding temperature and1000 gf bonding force. The transmission electron microscopy results showed that intermetallic compounds including Cu 6 Sn 5and Cu 3 Sn existed at bonding interface, which indicated that signifi cant atomic diff usion had occurred between Cu-Co-Pmicro-cones and Sn based solder. Probable mechanisms for low-temperature insertion bonding were discussed.
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