Browsing by Author "Lin, C. K."

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A Theoretical Investigation of Surface-enhanced Sum-frequency Generation
(2016-01-01)
Yeh, Y. L.
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Lei, J.
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Chen, S. Y.
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Chang, A. H. H.
;
Lin, C. K.
Following the surface enhanced Raman scattering (SERS), we shall investigate the possibility of observing surface-enhanced sum-frequency generation (SESFG), which refers to the transformation of ordinary vibrational SFG (i.e. singly resonant) into SESFG. Two mechanisms of SESFG will be studied; one is due to the transformation of singly-resonant vibrational SFG into doubly resonant vibrational SFG (that is, both vibrationally resonant and Raman-scattering resonant) and the other is due to the enhancement of the polarizability in addition to the original vibrational resonance in vibrational SFG.
A Theoretical Investigation of Surface-enhanced Sum-frequency Generation
(2016-01)
Yeh, Y. L.
;
Lei, J.
;
Chen, S. Y.
;
Chang, A. H. H.
;
Lin, C. K.
Following the surface enhanced Raman scattering (SERS), we shall investigate the possibility of observing surface-enhanced sum-frequency generation (SESFG), which refers to the transformation of ordinary vibrational SFG (i.e. singly resonant) into SESFG. Two mechanisms of SESFG will be studied; one is due to the transformation of singly-resonant vibrational SFG into doubly resonant vibrational SFG (that is, both vibrationally resonant and Raman-scattering resonant) and the other is due to the enhancement of the polarizability in addition to the original vibrational resonance in vibrational SFG.
Asymmetrical growth of Cu6Sn5 intermetallic compounds due to rapid thermomigration of Cu in molten SnAg solder joints
(2012-10-01)
Guo, Ming-Yung
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Lin, C. K.
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Chen, Chih
;
Tu, K. N.
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材料科學與工程學系
We observed asymmetrical growth of Cu6Sn5 intermetallic compounds (IMCs) on the two interfaces of Cu/SnAg/Cu solder joints during reflow at 260 degrees C on a hot plate. The IMCs grew to 12.3 mu m on the cold end and 3.5 mu m on the hot end after reflow for 40 min. However, the consumption of Cu on the cold end is less than that on the hot end. We propose that rapid thermomigration of Cu is responsible for the asymmetrical growth of the IMCs. With the simulated thermal gradient of 51 degrees C/cm across the liquid solder, the heat of transport of Cu is calculated as 20 kJ/mol. (C) 2012 Elsevier Ltd. All rights reserved.
Communication-Formation of Porous Cu3Sn by High-Temperature Current Stressing
(2016)
Lin, C. K.
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Chen, Chih
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Chu, David T.
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Tu, K. N.
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材料科學與工程學系
Cu3Sn is a compound commonly formed in solder joints on Cu. In this study, two different Cu3Sn structures were observed at different stages of current stressing. A normal layer-type and pore-less Cu3Sn structure was obtained at the current density of 2.27 x 10(4) A/cm(2) at 222 degrees C after 12 h. However, a porous Cu3Sn structure was formed under the same current stressing conditions after 22 h. The formation of porous Cu3Sn is explained by the mechanisms of phase transformation and reaction. The porous Cu3Sn structure is frequently observed in Cu/solder/Cu microbumps with a reduced solder height after electromigration tests. (C) 2016 The Electrochemical Society. All rights reserved.
Electrical characterization of fine-pitch compliant bumps
(2009)
Lin, C. K.
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Chen, Chih
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Chang, Shyh-Ming
;
An, Chao-Chyun
;
Lee, Hsiao Ting
The electrical characterization of fine-pitch compliant Au bumps is investigated in this study. Compliant Au bumps of 20 microns pitch were fabricated on a glass substrate for chip-on-glass application. Kelvin probes are fabricated and employed to measure the bump resistance. The resistance ranges from 1.0 to 4.5 ohms, depending on process parameters. Current-carrying capability for these bumps is examined. Electromigration test is performed and it is found that the failure occurs in the wiring Al line on the glass substrate, indicating that the Au bumps have high electromigration resistance. The bump resistance is also measured during thermal cycling from 30 to 110 degrees C, and the resistance increases less than 50 % after 6 cycles. Aging test is also carried out at 60 degrees C and 40 mA, and the failure time is 561 hours.
Electrical characterization of fine-pitch compliant bumps
(2008)
Lin, C. K.
;
Chen, Chih
;
Chang, Shyh-Ming
;
An, Chao-Chyun
;
Lee, Hsiao Ting
The electrical characterization of fine-pitch compliant Au bumps is investigated in this study. Compliant Au bumps of 20 microns pitch were fabricated on a glass substrate for chip-on-glass application. Kelvin probes are fabricated and employed to measure the bump resistance. The resistance ranges from 1.0 to 4.5 ohms, depending on process parameters. Current-carrying capability for these bumps is examined. Electromigration test is performed and it is found that the failure occurs in the wiring Al line on the glass substrate, indicating that the Au bumps have high electromigration resistance. The bump resistance is also measured during thermal cycling from 30 to 110 degrees C, and the resistance increases less than 50% after 6 cycles. Aging test is also carried out at 60 degrees C and 40 mA, and the failure time is 561 hours.
Electromigration study of eutectic SnPb flip-chip solder joints on ceramic substrates
(2008)
Lin, C. K.
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Chen, Chih
;
Yu, H. M.
;
Lan, J. K.
;
Lee, D. L.
This study investigates electromigration Study of eutectic SnPb flip-chip solder joints on ceramic substrates. The under bump metallization (UBM) structure consist,; of 5-mu m Cu / 3-mu m Ni under bump metallization (UBM). Under the current stressing by 0.9A tit 150 degrees C, we did not find void formation but a large amount of intermetallic compound (IMC) of Cu(6)(Sn, Ni)(5) were fornied when the bump resistance increased 10 m Omega. Three-dimensional electrical Simulation by finite element analysis was carried out to simulate the current density distribution in solder joints with slit Cu traces. It is found that the current density was almost uniformly distributed in solder joint for this structure. It is found that the bump resistance only increases 0.07m Omega when half of the solder bump was transformed into Cu(6)Sn(5) IMC. The reason for the low crowding effect in the solder joints will be discussed in the conference.
Experimental and simulation analysis of concave-down resistance curve during electromigration in solder joints
(2014-02-28)
Lin, C. K.
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Chang, Yuan Wei
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Chen, Chih
;
材料科學與工程學系
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Department of Materials Science and Engineering
Resistance curves play a crucial role in detecting damage of solder joints during electromigration. In general, resistance increases slowly in the beginning, and then rises abruptly in the very late stage; i.e., the resistance curve behaves concave-up. However, several recent studies have reported concave-down resistance curves in solder joints with no satisfactory explanation for the discrepancy. In this study, electromigration failure mode in Sn2.5Ag solder joints was experimentally investigated. The bump resistance curve exhibited concave-down behavior due to formation of intermetallic compounds (IMCs). In contrast, the curve was concave-up when void formation dominated the failure mechanism. Finite element simulation was carried out to simulate resistance curves due to formation of IMCs and voids, respectively. The simulation results indicate that the main reason causing the concave-down curve is rapid formation of resistive Cu6Sn5 IMCs in the current-crowding region, which are 9 times larger than Cu IMCs. Therefore, when Cu reacted with Sn to form Cu6Sn5 IMCs, resistance increased abruptly, resulting in the concave-down resistance curve. (C) 2014 AIP Publishing LLC.
Formation of Sn-rich phases via the decomposition of Cu6Sn5 compounds during current stressing
(2014-06-01)
Lin, C. K.
;
Liu, Chien-Ming
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Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
This study examined the formation of Sn-rich phases in the matrix of Cu-Sn-Ni intermetallic compounds (IMCs) after current stressing of 1.2 X 104 A/cm(2) at 160 degrees C. The Sn-rich phases were formed at the cathode end of the solder joints with Cu metallization, and this formation was attributed to the decomposition of Cu6Sn5 IMCs. When the Cu6Sn5 IMCs were transformed into Cu3Sn during current stressing, Sn atoms were released. When the supply of Cu atoms became deficient, Sn atoms accumulated to form Sn-rich phases among the Cu-Sn-Ni IMCs. (C) 2014 Elsevier B.V. All rights reserved.
Temperature-dependent failure mechanism of SnAg solder joints with Cu metallization after current stressing: Experimentation and analysis
(2013-09-21)
Lin, C. K.
;
Tsao, Wei An
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Liang, Y. C.
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Chen, Chih
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材料科學與工程學系
Temperature-dependent electromigration failure was investigated in solder joints with Cu metallization at 126 degrees C, 136 degrees C, 158 degrees C, 172 degrees C, and 185 degrees C. At 126 degrees C and 136 degrees C, voids formed at the interface of Cu6Sn5 intermetallic compounds and the solder layer. However, at temperature 158 degrees C and above, extensive Cu dissolution and thickening of Cu6Sn5 occurred, and few voids were observed. We proposed a model considering the flux divergency at the interface. At temperatures below 131 degrees C, the electromigration flux leaving the interface is larger than the in-coming flux. Yet, the in-coming Cu electromigration flux surpasses the out-going flux at temperatures above 131 degrees C. This model successfully explains the experimental results. (C) 2013 AIP Publishing LLC.
THEORIES AND QUANTUM CHEMICAL CALCULATIONS OF LINEAR AND SUM-FREQUENCY GENERATION SPECTROSCOPIES, AND INTRAMOLECULAR VIBRATIONAL REDISTRIBUTION AND DENSITY MATRIX TREATMENT OF ULTRAFAST DYNAMICS
(2015-01-01)
Yang, L.
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Niu, Y. L.
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Lin, C. K.
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Hayashi, M.
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Zhu, C. Y.
Theory and Applications of Sum-Frequency Generations
(2014-01-01)
Lin, C. K.
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Yang, L.
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Hayashi, M.
;
Zhu, C. Y.
;
Fujimura, Y.
The SFG technique has become popular since the pioneering work conducted by Shen's group in late 1980s. Combined the advantages of other surface-detecting techniques, the SFG technique could identify both chemical species and orientations adsorbed on surfaces or inserted between surfaces. In view of the recent tremendous experimental activities of SFG in surface chemistry, biochemistry and material sciences, quantum chemical calculations of SFG spectra to analyze the experimental SFG spectra are badly needed. In this paper we presented the theoretical expressions of various SFG techniques and showed how to employ the quantum chemical calculations to simulate the corresponding SFG spectra.