Browsing by Author "Duh, JG"

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Effects of Ni thickness and reflow times on interfacial reactions between Ni/Cu under-bump metallization and eutectic Sn-Pb solder in flip-chip technology
(2003-02-01)
Huang, CS
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Duh, JG
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Chen, YM
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Wang, JH
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材料科學與工程學系
Flip-chip interconnection technology plays a key role in today's electronics packaging. Understanding the interfacial reactions between the solder and under-bump metallization (UBM) is, thus, essential. In this study, different thicknesses of electroplated Ni were used to evaluate the phase transformation between Ni/Cu under-bump metallurgy and eutectic Sn-Pb solder in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure for the flip-chip technology. Interfacial reaction products varied with reflow times. After the first reflow, layered (Ni1-x,Cu-x)(3)Sn-4 was found between solder and Ni. However, there were two interfacial reaction products formed between solders and the UBM after three or more times reflow. The layered (Ni1-xCux)(3)Sn-4 was next to the Ni/Cu UBM. The islandlike (Cu1-y,Ni-y)(6)Sn-5 was formed between (Ni,Cu)(3)Sn-4 and solders. The amounts of (Cu1-y,Ni-y)(6)Sn-5 intermetallic compound (IMC) could be related to the Ni thickness and reflow times. In addition, the influence of Cu contents on phase transformation during reflow was also studied.
Low temperature sintering and crystallisation behaviour of low loss anorthite-based glass-ceramics
(2003-02-15)
Lo, CL
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Anorthite-based glass-ceramics including TiO2 as nucleating agent were melted and quenched in this study. The effect of particle size on the sintering behaviour of glass powders was investigated in order to obtain low-temperature sintered glass-ceramics. Anorthite glass-ceramic starts to densify at the transition temperature of glass (T-g = 770degreesC) and is fully sintered before the crystallisation occurrence (880degreesC). Therefore, a dense and low-loss glass-ceramic with predominant crystal phase of anorthite is achieved by using fine glass powders (D-50 = 0.45 mum) fired at 900degreesC. The as-sintered density approaches 99% theoretical density and the apparent porosity is as low as 0.05 Vol%. The dense and crystallized anorthite-based glass-ceramic exhibits a fairly low dielectric loss of 4 x 10(-4) at 1 MHz and a thermal expansion coefficient of 4.5 x 10(-6)degreesC(-1). Furthermore, the microwave characteristics were measured at 10 GHz with the results of K = 9.8, Of = 2250, and temperature coefficient of resonant frequency tau(f) = -30 ppm/degreesC. (C) 2003 Kluwer Academic Publishers.
Low-voltage cathodoluminescence properties of the Y2O2S : Eu red light emitting phosphor screen in field-emission environments
(2002-07-01)
Lo, CL
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Y2O2S: Eu phosphors doped with different concentrations of Eu were fabricated by a high-temperature flux fusion method. For applications in field emission displays, phosphor powders were electrophoretically deposited on an indium-tin oxide coated glass substrate to form a phosphor screen. Cathodoluminescence properties of phosphor screens were examined at a low excitation voltage of 5 kV in a high-vacuum chamber (5 x 10(-8) Torr), and characteristics of Y2O2S: Eu phosphors, including brightness and wavelength data, are presented and discussed. The red emission brightness for the Y2O2S: Eu phosphor screens can be significantly improved by adjustment of the Eu additions, which decrease the x coordinate slightly, while having no significant influence on the color performance. Considering the effects of Eu concentrations on red light emission spectra and brightness for Y2O2S: Eu phosphor screens, it is found that brightness for Y2O2S: Eu phosphor screens could be obtained up to 120 cd/m(2) with chromaticity of x = 0.63 and y = 0.36, and the Eu dopant concentration is suggested to be in the range 6-7.5 wt %. (C) 2002 The Electrochemical Society.
Luminescent mechanisms of ZnS : Cu : Cl and ZnS : Cu : Al phosphors
(2001-07-23)
Chen, YY
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Duh, JG
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Chiou, BS
;
Peng, CG
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電子工程學系及電子研究所
ZnS:Cu:Cl and ZnS:Cu:Al phosphors are fabricated by a flux fusion method to be used in cathode ray tube (CRT) monitors for green emission. The emission spectra of the phosphors depend on the Cu concentration. A series of luminescence measurements have been conducted, and several models are applied to explain the luminescent phenomenon of these phosphors. It is revealed that ZnS:Cu:Cl and the ZnS:Cu:Al phosphors exhibit green emission yet their luminescence mechanisms are different. The emission spectrum from the as-fabricated green phosphors is not a typical Gaussian distribution. The combination of blue and green band luminescence is attributed to the green-luminescence quenching derived from the interstitial Cu+ ions. (C) 2001 Elsevier Science B.V. All rights reserved.
Metallurgical reaction of the Sn-3.5Ag solder and Sn-37Pb solder with Ni/Cu under-bump metallization in a flip-chip package
(2003-12-01)
Huang, CS
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Duh, JG
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Chen, YM
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材料科學與工程學系
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Department of Materials Science and Engineering
Several international legislations recently banned the use of Pb because of environmental concerns. The eutectic Sn-Ag solder is one of the promising candidates to replace the conventional Sn-Pb solder primarily because of its excellent mechanical properties. In this study, interfacial reaction of the eutectic Sn-Ag and Sn-Pb solders with Ni/Cu under-bump metallization (UBM) was investigated with a joint assembly of solder/Ni/Cu/Ti/Si(3)N(4)/Si multilayer structures. After reflows, only one (Ni,Cu)(3)Sn(4) intermetallic compound (IMC) with faceted and particlelike grain feature was found between the solder and Ni. The thickness and grain size of the IMC increased with reflow times. Another (Cu,Ni)(6)Sn(5) IMC with a rod-type grain formed on (Ni,Cu)(3)Sn(4) in the interface between the Sn-Pb solder and the Ni/Cu UBM after more than three reflow times. The thickness of the (Ni,Cu)(3)Sn(4) layer formed in the Sn-Pb system remained almost identical despite the numbers of reflow; however, the amounts of (Cu,Ni)(6)Sn(5) IMC increased with reflow times. Correlations between the IMC morphologies, Cu diffusion behavior, and IMC transformation in these two solder systems will be investigated with respect to the microstructural evolution between the solders and the Ni/Cu UBM. The morphologies and grain-size distributions of the (Ni,Cu)(3)Sn(4) IMC formed in the initial stage of reflow are crucial for the subsequent phase transformation of the other IMC.
Microstructure characteristics for anorthite composite glass with nucleating agents of TiO2 under non-isothermal crystallization
(2002-10-03)
Lo, CL
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Duh, JG
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Chiou, BS
;
Lee, WH
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電子工程學系及電子研究所
The anorthite-based composite glass doped with TiO2 and B2O3 was prepared by quenching of molten droplets. Phase development and crystals microstructure of glass were investigated under non-isothermal conditions. A glass transition temperature of 770degreesC and an exothermal peak around 870degreesC in the DTA trace was associated with anorthite crystallization (CaAl2Si2O8). For glass specimens under nucleation and crystallization heat-treatment, the final predominant phase was identified as anorthite. Anorthite crystals show preferential nucleation at specific sites with rutile TiO2 crystals precipitated from the glassy matrix and anorthite crystallization is governed by heterogeneous volume nucleation. The introduced TiO2 plays the role of nucleating agents to reduce the crystallization temperature lower than 900degreesC for anorthite-based glass-ceramics. Chemical compositions could be related to the crystal microstructures on different characteristic regions. It was observed that the sintering aid of B2O3 neither reacted with nor dissolved in the anorthite or rutile TiO2 crystals, and remained a glassy phase in the matrix. Occurrence of acicular precipitations was attributed to the orientation growth of TiO2 crystals. Anorthite crystals were observed to grow with the forms of feathery-spherical particles, having a tendency to coalescence into a huge domain. (C) 2002 Elsevier Science Ltd. All rights reserved.
Synthesis of Eu3+-activated yttrium oxysulfide red phosphor by flux fusion method
(2001-08-15)
Lo, CL
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Duh, JG
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Chiou, BS
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Peng, CC
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Ozawa, L
Synthesis of the yttrium oxysulfide red phosphor by the flux fusion method was presented. Effects of flux compositions and sintering conditions on the shape and size distribution of phosphor were studied. In addition, the optimization of firing conditions was also conducted. After firing phosphor with a flux containing (S + Na2CO3 + Li3PO4 + K2CO3)/(S + Li2CO3 + K2CO3) at a ratio of 3:1 at 1150 degreesC for 2.5 h, Y2O2S:Eu3+ phosphor was obtained without any Y2O3 as a second phase. The nearly spherical phosphor powder exhibited a mean particle size of 3 mum and a rather sharp particle size distribution. Y2O2S:Eu3+ red phosphor illuminated the most red color light with an applied probe current density of 0.51 muA/cm(2). (C) 2001 Elsevier Science BN. All rights reserved.
Temperature cycling effects between Sn/Pb solder and electroless copper plated AIN substrate
(1995-12-01)
Chiou, BS
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Chang, JH
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Duh, JG
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Thermal cycling effects on Sn/Pb solder and electroless Cu-plated AIN substrates are investigated. X-ray diffraction patterns reveal the existence of Cu2O for the electroless Cu-plated AIN after thermal cycling in an environmental chamber. Moisture in the chamber results in the oxidation of electroless plated Cu and fracture takes place at the Cu2O/Cu interface. The oxidation of Cu is also confirmed by Auger depth profile and electrical sheet resistance measurement. For the solder/Cu/AIN system, fracture occurs at the Cu/solder interface. No intermetallic compounds between solder and Cu are found after thermal cycling. Stress resulting from the thermal expansion mismatch is the major cause of loss of adhesion.
The effect of substrate surface roughness on the wettability of Sn-Bi solders
(2000-06-01)
Chen, YY
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The effect of substrate surface roughness on the wettability of Sn-Bi solders is investigated by the eutectic Sn-Bi alloy on Cu/Al2O3 substrates at 190 degrees C. To engineer the surface with different roughnesses, the Cu-side of the substrates is polished with sandpaper with abrasive number 100, 240, 400, 600, 800, 1200, and 1 mu m alumina powder, respectively. Both dynamic and static contact angles of the solder drops are studied by the real-time image in a dynamic contact angle analyzer system (FTA200). During dynamic wetting, the wetting velocity of the solder drop decreases for the rougher surface. However, the time to reach the static contact angle seems to be identical with different substrate surface roughness. The wetting tip of the solder cap exhibits a waveform on the rough surface, indicating that the liquid drop tends to flow along the valley. As the solder drops reach a static state, the static contact angle increases with the substrate surface roughness. This demonstrates that the wettability of solders degrades as the substrates become rough.
The influence of washing and calcination condition on urea-derived ceria-yttria-doped tetragonal zirconia powders
(2001-02-15)
Lin, JD
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The influence of washing and calcination conditions on the powder characteristics of urea-derived ceria-yttria-doped tetragonal zirconia powders (Ce-Y-TZP) ceramics are studied. The use of urea hydrolysis followed by acetone-toluene-acetone (ATA) washing can produce a finer and more sinterable Ce-Y-TZP powder as compared to that washed by alcohol. It is observed that as the calcination temperature is raised to 800 degreesC for 2 h, the sintered density achieves the highest value regardless of the increase of monoclinic content in as-derived powders. The higher the calcination temperature, the more the monoclinic content. The transformability of tetragonal phase is related to the A, temperature and tetragonality. The monoclinic content in as-derived powders after calcination and ball-milling processes is proportional to the A, temperature and tetragonality of tetragonal phase. (C) 2001 Elsevier Science B.V. All rights reserved.
Thermal cycling test in Sn-Bi and Sn-Bi-Cu solder joints
(2000-11-01)
Miao, HW
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The eutectic SnBi solder alloy is a candidate for Pb-free replacement of the conventional eutectic SnPb solders. This study presents series of results on the binary eutectic SnBi and ternary SnBi-1 wt % Cu a solder joints. Compositional analysis and wettability of the as-fabricated solder alloys are reported. In addition, microstructure, adhesion strength, fracture surface and contact resistance of the solder joints are also evaluated. The results of the wetting balance show that the addition of 1 wt % Cu has little effect on the contact angle of the eutectic SnBi solder alloy with various metallization layers. The adhesion strength of solder joints degrades abruptly after 2000 thermal cycles. In addition, thermal cycling would result in cracking in the solder joints, which is due to the mismatch in thermal expansion coefficients. Portions of the thermal fatigue cracks nucleate at the edge of the solder fillet, and then propagate along the solder/conductor interface. Some cracks are, however, through the Al2O3 substrate. The contact resistance of the solder/Cu joint does not increase after thermal cycling since the resistivity of Cu6Sn5 is lower than that of the solder. The solder joints of 42Sn-58Bi/Cu, SnBi-1Cu/Cu, 42Sn-58Bi/PtAg, and SnBi-1Cu/PtAg assemblies maintain their integrity after 2000 thermal cycles since the increase in contact resistance is rather small (DeltaR <0.5 m Omega). (C) 2000 Kluwer Academic Publishers.
Wettability of electroless Ni in the under bump metallurgy with lead free solder
(2001-05-01)
Young, BL
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This study investigates the wettability of several lead-free solders, including Sn, Sn-Ag, and Sn-Bi, on electroless Ni (EN) with various phosphorus contents. The role of phosphorus on solder wettability is studied. Microstructure evolution in the lead-free solder/EN joint is investigated with the aid of electron probe microanalyzer (EPMA) to relate metallurgical reactions between the solder and the EN. The Sn solder exhibits better wettability on EN, while the Sn-Bi solder has a larger contact angle. Wettability degrades as the phosphorus content in EN decreases. The dependence of wetting angle on the phosphorous content can be attributed to the surface roughness and density of EN, along with the interfacial reaction between the solders and EN. An EPMA analysis reveals the presence of a Sn-Bi-Ni-P solid solution at the interface of solder/EN joints due to the interdiffusion of major constituent Ni and Sn. The interaction zone of the solid solution increases with increasing temperature. Wettability of Pb-free solders on EN degrades with the presence of NiO due to oxidation or the existence of Ni3P due to precipitation after annealing. For an adequate wetting behavior in the Sn (Sn-Bi, Sn-Ag)/EN joint, EN deposited with phosphorus contents in the range of 9 to 12 wt.% is suggested.
Wettability of electroplated Ni-P in under bump metallurgy with Sn-Ag-Cu solder
(2006-01-01)
Lin, YC
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Duh, JG
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Chiou, BS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Nickel plating has been used as the under bump metallurgy (UBM) in the microelectronics industry. In this study, the electroplating process was demonstrated to be a good alternative approach to produce the Ni-P layer as UBM. The wettability of several commercial solder pastes, such as Sn-3.5Ag, Sn-37Pb, and Sn-3Ag-0.5Cu solder, on electroplated Ni-P with various phosphorous contents (7 wt.%, 10 wt.%, and 13 wt.%) was investigated. The role of phosphorus in the wettability was probed. The surface morphology and surface roughness in electroplated Ni-P was observed with the aid of both field emission scanning electron microscope (SEM) and atomic force microscope (AFM). The correlation between wettability and phosphorus contents in electroplated Ni-P was evaluated. As the phosphorous contents increased, the surface morphology of the Ni-P deposit was smoother and surface roughness of Ni-P became smaller. The improvement of surface morphology and surface roughness enhanced the wettability of electroplated Ni-P. The interfacial reaction between lead-free solder and electroplating Ni-P UBM was also investigated.