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2 results on '"Yunfei En"'

1. Method of Measuring the Mismatch of Parasitic Capacitance in MEMS Accelerometer Based on Regulating Electrostatic Stiffness

Author

Xianshan Dong, Shaohua Yang, Junhua Zhu, Yunfei En, and Qinwen Huang

Subjects
MEMS accelerometer, mismatch of parasitic capacitance, electrostatic stiffness, Mechanical engineering and machinery, TJ1-1570
Abstract

For the MEMS capacitive accelerometer, parasitic capacitance is a serious problem. Its mismatch will deteriorate the performance of accelerometer. Obtaining the mismatch of the parasitic capacitance precisely is helpful for improving the performance of bias and scale. Currently, the method of measuring the mismatch is limited in the direct measuring using the instrument. This traditional method has low accuracy for it would lead in extra parasitic capacitive and have other problems. This paper presents a novel method based on the mechanism of a closed-loop accelerometer. The strongly linear relationship between the output of electric force and the square of pre-load voltage is obtained through theoretical derivation and validated by experiment. Based on this relationship, the mismatch of parasitic capacitance can be obtained precisely through regulating electrostatic stiffness without other equipment. The results can be applied in the design of decreasing the mismatch and electrical adjusting for eliminating the influence of the mismatch.

Published
2018
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2. Microstructure and Grain Orientation Evolution in SnPb/SnAgCu Interconnects Under Electrical Current Stressing at Cryogenic Temperature

Author

Xing Fu, Huang Yun, He Xiaoqi, Ruohe Yao, Yunfei En, Bin Zhou, Si Chen, and Hongtao Chen

Subjects
Materials science, Scanning electron microscope, EBSD, Current crowding, Intermetallic, grain orientation, Electromigration, lcsh:Technology, Article, law.invention, electromigration, IMC, law, General Materials Science, Composite material, cryogenic, lcsh:Microscopy, lcsh:QC120-168.85, lcsh:QH201-278.5, lcsh:T, Microstructure, Cathode, lcsh:TA1-2040, Grain boundary, lcsh:Descriptive and experimental mechanics, lcsh:Electrical engineering. Electronics. Nuclear engineering, lcsh:Engineering (General). Civil engineering (General), lcsh:TK1-9971, Electron backscatter diffraction
Abstract

Electromigration was characterized at the cathode Cu/solder interface&mdash, without the effect of Joule heating&mdash, by employing scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analyses. Rapid (Cux,Ni1&minus, x)6Sn5 intermetallic compound (IMC) growth was observed at the anomalous region at the cathode end due to the effect of current crowding. The abnormal isotropic diffusion and parallel distribution of Pb were characterized in an ultra-low temperature environment in a monocrystalline structure stressed at &minus, 196 &deg, C. The interesting results were attributed to crystallographic transformation due to the simultaneous effect of cryogenic and electrical stressing. The diffusion behavior of Pb atoms in face-centered cubic lattices performed isomorphism. As a result, Pb atoms of the bump gathered at the high-energy grain boundaries by diffusing through the face-centered cubic lattices around the long grain boundary, eventually forming a long-range distribution and accumulation of Pb elements. Our study may provide understanding of cryogenic electromigration evolution of the Cu/solder interface and provide visual data for abnormal lattice transformation at the current stressing.

Published
2019

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