Browsing by Author "Wang, H"

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Interfacial reaction and shear strength of Pb-free SnAg2.5Cu0.86b0.5 and SnAg3.0Cu0.5Sb0.2 solder bumps on Au/Ni(P) metallization
(2006-06-29)
Hsu, YC
;
Huang, YM
;
Chen, C
;
Wang, H
;
材料科學與工程學系
This study investigates the metallurgical reaction and shear strength of Pb-free SnAg2.5Cu0.8Sb0.5 and SnAg3.0Cu0.5Sb0.2 solder bumps on Au/Ni(P) metallization pads. It is found that (Cu,Ni)(6)Sn-5 intermetallic compound (IMC) formed at the interface between the Sn2.5Ag0.8Cu0.5Sb solder and the metallization pad; whereas (Cu,Ni)(6)Sn-5 and (Ni,Cu)(3)Sn-4 IMCs formed when the SnAg3.0Cu0.5Sb0.2 reacted with the Au/Ni(P) metallization pad. The difference in the Cu concentration in the two solders may be responsible for the different interfacial IMC formation. The shear strengths for the SnAg2.5Cu0.8Sb0.5, SnAg3.0Cu0.5Sb0.2, SnAg3.0Cu0.5, and SnAg4.0Cu0.5 solders were also measured. The shear strength test revealed that the SnAg2.5Cu0.8Sb0.5 solder has the highest shear strength, which may be due to the solid-solution strengthening of the Sb atoms. (c) 2005 Elsevier B.V. All rights reserved.
Second-harmonic generation from regeneratively amplified femtosecond laser pulses in BBO and LBO crystals
(1998-01-01)
Zhang, JY
;
Huang, JY
;
Wang, H
;
Wong, KS
;
Wong, GK
The spectral and temporal characteristics and optical-conversion efficiency of similar to 150-fs laser pulses at 400 nm generated by second-harmonic generation (SHG) of a regeneratively amplified mode-locked Ti:sapphire laser were investigated both theoretically and experimentally. The theoretical investigation was done by taking into account cubic nonlinearity, pulse walk-off, group-velocity dispersion, Kerr nonlinearity, quadratic broadening, frequency chirping of the fundamental pulse, and higher-order nonlinear mixing such as backconversion and optical parametric processing. The experimental studies of the effects of crystal length and pumping intensity on the pulse duration, the spectrum, and the optical-conversion efficiency of the SHG were carried out in BBO and LBO crystals of various thicknesses and compared with the theory. It was found that in a non-transform-limited pulse, the most significant contribution to the temporal and spectral distortion of the similar to 150-fs SHG pulses is mainly due to the chirping of the fundamental beam and self-phase modulation at high pumping intensity and long crystal length. The optimum crystal length and pumping intensity for obtaining a high optical-conversion efficiency and a pure spectrum in SHG are also calculated and experimentally investigated. It was found that a transform-limited fundamental pulse is essential to obtain a high conversion efficiency and to preserve the temporal profile of the second-harmonic pulse. It is also found that for a non-transform-limited similar to 150-fs pulse, a 0.5-0.6-mm BBO crystal and a modest pumping intensity of similar to 40 GW/cm(2) are the most suitable for SHG. (C) 1998 Optical Society of America.
Second-harmonic generation from regeneratively amplified femtosecond laser pulses in BBO and LBO crystals
(1998-01-01)
Zhang, JY
;
Huang, JY
;
Wang, H
;
Wong, KS
;
Wong, GK
The spectral and temporal characteristics and optical-conversion efficiency of similar to 150-fs laser pulses at 400 nm generated by second-harmonic generation (SHG) of a regeneratively amplified mode-locked Ti:sapphire laser were investigated both theoretically and experimentally. The theoretical investigation was done by taking into account cubic nonlinearity, pulse walk-off, group-velocity dispersion, Kerr nonlinearity, quadratic broadening, frequency chirping of the fundamental pulse, and higher-order nonlinear mixing such as backconversion and optical parametric processing. The experimental studies of the effects of crystal length and pumping intensity on the pulse duration, the spectrum, and the optical-conversion efficiency of the SHG were carried out in BBO and LBO crystals of various thicknesses and compared with the theory. It was found that in a non-transform-limited pulse, the most significant contribution to the temporal and spectral distortion of the similar to 150-fs SHG pulses is mainly due to the chirping of the fundamental beam and self-phase modulation at high pumping intensity and long crystal length. The optimum crystal length and pumping intensity for obtaining a high optical-conversion efficiency and a pure spectrum in SHG are also calculated and experimentally investigated. It was found that a transform-limited fundamental pulse is essential to obtain a high conversion efficiency and to preserve the temporal profile of the second-harmonic pulse. It is also found that for a non-transform-limited similar to 150-fs pulse, a 0.5-0.6-mm BBO crystal and a modest pumping intensity of similar to 40 GW/cm(2) are the most suitable for SHG. (C) 1998 Optical Society of America.