冷却速度对无铅焊料Sn-3．5Ag合金微观组织和显微硬度的影响

在～10^2K／s、～10^3K／s和～10^4K／s的冷速条件下研究了凝固速度对无铅焊料Sn-3．SAg合金微观组织和显微硬度的影响。结果表明：由于非平衡凝固条件下动力学过冷的影响，导致了该共晶合金实际凝固过程开始于平衡共晶凝固点以下，合金凝固组织中包含初生β-Sn枝晶，且该初生β-Sn枝晶组织随合金凝固速度的提高而发生细化。另外，维氏硬度测试结果表明，无铅焊料Sn-3．5ag合金在不同冷速条件下的凝固组织与显微硬度的关系符合经典Hall-Petch关系式，即初生β-Sn枝晶细化能显著提高焊料合金的显微硬度。     

冷却速度对无铅焊料Sn-3.5Ag合金微观组织和显微硬度的影响

在～102K/s、～103K/s和～104K/s的冷速条件下研究了凝固速度对无铅焊料Sn-3.5Ag合金微观组织和显微硬度的影响.结果表明:由于非平衡凝固条件下动力学过冷的影响,导致了该共晶合金实际凝固过程开始于平衡共晶凝固点以下,合金凝固组织中包含初生β-Sn枝晶,且该初生β-Sn枝晶组织随合金凝固速度的提高而发生细化.另外,维氏硬度测试结果表明,无铅焊料Sn-3.5Ag合金在不同冷速条件下的凝固组织与显微硬度的关系符合经典Hall-Petch关系式,即初生β-Sn枝晶细化能显著提高焊料合金的显微硬度.     

添加Ag元素对铝软钎焊用Sn-1.5Zn系钎料性能的影响

研究了添加不同含量Ag元素对铝软钎焊用Sn-1.5Zn系钎料合金的熔化特性、显微组织、润湿性及钎焊接头抗腐蚀性能的影响。研究结果表明,Ag元素的添加缩短了Sn-1.5Zn钎料的熔程,细化了显微组织;采用润湿平衡法测量结果发现,添加Ag元素提高了钎料对铝基体的最大润湿力Fmax,但使润湿时间t0增加;采用3%(质量分数)浓度盐水溶液浸泡焊点实验结果表明,添加Ag元素提高了钎焊接头的抗腐蚀性。     

锌对Sn3.5Ag0.5Cu钎料合金微结构及性能的影响

运用莱卡显微镜、X射线衍射仪等仪器设备,研究了添加元素Zn对Sn3.5Ag0.5Cu钎料合金微结构及性能的影响.结果表明,Zn与Cu、Ag形成化合物AgZn、CuZn3,能显著细化Sn3.5Ag0.5Cu钎料组织;添加元素Zn后的Sn3.5Ag0.5Cu钎料合金的显微硬度提高11%,蠕变抗力也得到明显提高;运用键参数函数理论分析了Zn对Sn3.5Ag0.5Cu钎料合金微结构及性能影响的作用机理.[作者单位].5Cu钎料;组织;性能;键参数函数     

Optical properties of silver sulphide thin films formed on evaporated Ag by a simple sulphurization method

Silver sulphide (Ag₂S) thin films were grown on the surface of silver films (Ag) deposited on glass substrate by using a simple chemical sulphurization method. According to X-ray diffraction analysis, the Ag₂S thin films display low intensity peaks at 34.48°, 36.56°, and 44.28°, corresponding to diffraction from (100), (112) and (103) planes of the acanthite phase (monoclinic). A model of the type Ag₂S/Ag/glass was deduced from spectroscopic ellipsometric measurements. Also, the optical constants (n, k) of the system were determined. Furthermore, the optical properties as solar selective absorber for collector applications were assessed. The optical reflectance of the Ag₂S/Ag thin film systems exhibits the expected behavior for an ideal selective absorber, showing a low reflectance in the wavelength range below 2 µm and a high reflectance for wavelengths higher than that value. An absorptance about 70% and an emittance about 3% or less were calculated for several samples.     

Influences of Ag and Au Additions on Structure and Tensile Strength of Sn-5Sb Lead Free Solder Alloy

It is important, for electronic application, to decrease the melting point of Sn-5Sb solder alloy because it is relatively high as compared with the most popular eutectic Pb-Sn solder alloy. Adding Au or Ag can decrease the onset melting temperature （233℃） of this alloy to 203,5℃ and 216℃, respectively. The results indicate that the Sn-5Sb-i.5Au alloy has very good ultimate tensile strength （UTS）, ductility, and fusion heat, which are better than both those of the Sn-5Sb-3.SAg and Sn-5Sb alloys. The formation of intermetallic compounds （IMCs） AuSn4 and Ag3Sn enhanced the SbSn precipitates in the solidification microstructure microstructure stability, while retained the formation of thus significantly improved the strength and ductility For all alloys, both UTS and yield stress （σy） increase with increasing strain rate and decrease with increasing temperature in tensile tests, but changes of ductility are generally small with inconsistent trends.     

Optical and structural characterization of silver islands films on glass substrates

Metal island films (MIFs) of Ag on glass substrates were fabricated by the e-beam evaporation technique. The dependence of the surface plasmon (SP) absorption properties on the deposition mass thickness and substrate temperature was quantified. The structural and optical characterization of the MIFs, obtained using spectrometry, grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscopy (AFM) evidences the evolution of SP characteristics depending on the fabrication parameters: the red shift of the absorption peaks with the increase of deposition thickness accompanied by peak widening and the blue-shift of peaks with the increase of deposition temperature followed by the peak narrowing. These findings were explained by the differences in the concentration, shape and size of the obtained silver islands.     

合金元素对Sn-57Bi无铅钎料组织及韧性的影响

研究了添加不同含量的合金元素Ag,Ge,Cu,Sb,Zn,Ce,P,Ni对Sn-57Bi钎料的熔化温度、润湿性能、冲击韧性和显微组织的影响。研究结果表明,合金元素的添加对于钎料的熔化特性的影响不大,P,Ni的加入会导致出现硬脆的Bi,削弱了钎料的性能,Ag3Sn和富锌相则在形状合适时可以强化钎料的性能。单独加入合金元素Ag,Ge,Zn,Cu可以改善钎料的塑韧性,Ag,Ge还可以提高钎料的屈服强度和接头的剪切强度。合金元素Sb,Ce,P,Ni的加入会弱化钎料的塑韧性。而在同时添加多种合金元素的钎料合金中,43Sn-Bi-1Ge-1Ag的改善效果最好。     

基于Ag(TCNQ)热透镜效应的全光型开关

Ag(TCNQ)是一种电荷转移型金属有机络合物。用真空蒸发与真空热压相结合的方法使它分散到PMMA ,PHPMA ,PC等高分子树脂中 ,制成了不含任何有机溶剂的透明光学薄膜 ,并证实了它具有光热透镜效应。     

Effect of heat-treatment on luminescence and structure of Ag nanoclusters doped oxyfluoride glasses and implication for fiber drawing

The effect of heat treatment on the structure and luminescence of Ag nanoclusters doped oxyfluoride glasses was studied and the implication for drawing the corresponding fibers doped with luminescent Ag nanoclusters has been proposed. The heat treatment results, first, in condensation of the Ag nanoclusters into larger Ag nanoparticles and loss of Ag luminescence, and further heat treatment results in precipitation of a luminescent-loss nano- and microcrystalline Ag phases onto the surface of the glass. Thus, the oxyfluoride fiber doped with luminescent Ag nanoclusters was pulled from the viscous glass melt and its attenuation loss was 0.19 dB/cm in the red part of the spectrum; i.e. near to the maximum of Ag nanoclusters luminescence band. The nucleation centers for the Ag nanoclusters in oxyfluoride glasses have been suggested to be the fluorine vacancies and their nanoclusters.     

Structural, electronic, and optical properties of nanocrystalline As-doped ZnO films on quartz substrates determined by Raman scattering and infrared to ultraviolet spectra

Nanocrystalline As-doped ZnO films with different laser power energy (40 mJ and 55 mJ) and As doping concentrations (C_As from 1% to 3%) have been grown on quartz substrates by pulsed laser deposition. The average grain size of the films was calculated from the (002) peak of x-ray diffraction patterns and is estimated to vary from 9 to 13 nm. Electronic transitions and optical properties of the films have been investigated by Raman scattering, far-infrared reflectance, and infrared-ultraviolet spectral transmittance technique. With increasing doping concentration, the A₁ longitudinal optical phonon mode shifts towards the lower energy side and can be described by (564-75C_As) cm^-1 owing to the increment of free carrier concentration. The E₁ transverse optical phonon frequency is located at about 415 cm^-1 and does not show an obvious decreasing trend with the C_As. The optical constants in the photon energy range of 0.5-6.5 eV have been extracted by fitting the experimental data with the Adachi's model. The refractive index dispersion in the transparent region can be well expressed by a Sellmeier's single oscillator function. Due to different doping concentration and hexagonal crystalline structure, the optical band gap of the films grown at 40 mJ linearly decreases with increasing As concentration. The phenomena agree well with the results from the theoretical calculations.     

Effect of Temperature on Pitting Corrosion Resistance of 316 Stainless Steel Coated by Cerium Oxide Film in 3.5% NaCl Solution

One of the main problems of stainless steel is its poor pitting corrosion resistance in the aggressive environment containing Cl-, such as seawater. In this paper we investigated the corrosion behavior of the 316 stainless steel coated by cerium oxide nanocoating prepared by sol-gel process. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） were used to study the corrosion behavior of cerium oxide nanocoatings in 3.5% NaCl solution. The microstructure of the cerium oxide was examined by scanning electron microscopy （SEM） and the formed phases was identified by X-ray diffraction （XRD）. The pitting corrosion resistance of the cerium oxide nanocoating was found to be improved after heat treatment of the cerium oxide nanocoating at 300℃ for 30 min.     

Influence of Thermal Cycling on the Microstructure and Shear Strength of Sn3.5Ag0.75Cu and Sn63Pb37 Solder Joints on Au/Ni Metallization

The influence of thermal cycling on the microstructure and joint strength of Sn3.5Ag0.75Cu （SAC） and Sn63Pb37 （SnPb） solder joints was investigated. SAC and SnPb solder balls were soldered on 0.1 and 0.9 μm Au finished metallization, respectively. After 1000 thermal cycles between -40℃ and 125℃, a very thin intermetallic compound （IMC） layer containing Au, Sn, Ni, and Cu formed at the interface between SAC solder joints and underneath metallization with 0.1 μm Au finish, and （Au, Ni, Cu）Sn4 and a very thin AuSn-Ni-Cu IMC layer formed between SAC solder joints and underneath metallization with 0.9 μm Au finish. For SnPb solder joints with 0.1 μm Au finish, a thin （Ni, Cu, Au）3Sn4 IMC layer and a Pb-rich layer formed below and above the （Au, Ni）Sn4 IMC, respectively. Cu diffused through Ni layer and was involved into the IMC formation process. Similar interfacial microstructure was also found for SnPb solder joints with 0.9μm Au finish. The results of shear test show that the shear strength of SAC solder joints is consistently higher than that of SnPb eutectic solder joints during thermal cycling.     

Effect of laser repetition frequency on the structural and optical properties of ZnO thin films by PLD

ZnO thin films were grown on Si (1 1 1) substrates by pulsed laser deposition (PLD) at various laser repetition frequency in order to investigate the structural and optical properties of the films. The optical properties of the films were studied by photoluminescence spectra using a 325 nm He-Cd laser. The structural properties of the films were investigated by XRD measurement. The results suggest that films grown at 5 Hz have excellent UV emission and high-quality crystallinity. Laser repetition frequency can affect the structural and optical properties obviously. In addition, the thickness of all samples is about 200 nm and is not as expected that the film thickness was in direct proportion to laser repetition frequency. The authors think that one laser pulse is not corresponding to one growth instantaneousness. There is a growth ambience containing essential components and partial pressure in the work cavity.     

Effects of nano-Al2O3 particles on microstructure and mechanical properties of Sn3.5Ag0.5Cu composite solder ball grid array joints on Sn/Cu pads

A Sn3.5Ag0.5Cu (SAC)–XAl₂O₃ nano-composite solder was prepared by adding 100 nm Al₂O₃ to SAC (wt.%) solder. The interfacial microstructures and mechanical properties of SAC–XAl₂O₃ nano-composite solder balls on immersion Sn surface finished BGA joints after multiple reflows was investigated. As a whole, adding Al₂O₃ nanoparticles to SAC solders significantly changed in the interfacial microstructure, and both scallop-type and prism-type modes were observed in the plain SAC solder and SAC–XAl₂O₃ nano-composite solder after reflowing, respectively. The nanoparticles suppressed the growth of the Cu₆Sn₅ layer, significantly improving the shear strength. The fracture surfaces of the plain SAC solder showed a semi-brittle fracture mode, but those of the SAC–XAl₂O₃ nano-composite solder exhibited typical ductile failures.     

退火温度对ZnO/Mo/ZnO透明导电薄膜结构及光电性能的影响

采用电子束蒸发法成功制备了透明导电的ZnO/Mo/ZnO(ZMZ)复合薄膜,研究了不同的退火温度对其电学和光学性质的影响规律。利用X射线衍射仪、扫描电子显微镜、X射线能谱仪、紫外可见分光光度计和四探针测试仪等检测手段对样品的性能进行了分析。实验结果表明:随着退火温度的升高,薄膜的结晶程度提高,晶粒尺寸增大;薄膜的电阻率先降低后升高;薄膜的光学透过率先升高后降低。当退火温度为250℃时,ZnO/Mo/ZnO薄膜具有最佳的综合光电性能,在400nm~900nm波长范围内最高透过率为81.4%,平均透过率高于80%,最低电阻率为1.71×10-4Ω·cm,表面电阻为15.5Ω/sq。研究表明所制备的ZMZ复合透明导电薄膜可应用于太阳能电池、液晶显示器等领域。     

Effect of nano-TiO<Subscript>2</Subscript> addition on the microstructure and bonding strengths of Sn3.5Ag0.5Cu composite solder BGA packages with immersion Sn surface finish

The effects of nano-TiO₂ particles on the interfacial microstructures and bonding strength of Sn3.5Ag0.5Cu composite solder joints in ball grid array packages with immersion Sn surface finishes have been investigated. Metallography reveals that addition of nano-TiO₂ particle retarded wicker-Cu₆Sn₅ IMC formed in the Sn3.5Ag0.5Cu composite solder joints. The thickness of the interfacial intermetallic compounds of the solder joint was reduced with increased additions of nano-TiO₂ particles (0.25–1.0 wt%), but further additions up to 1.25 wt% decreased the beneficial influence. This indicates that the presence of a small amount of nano-TiO₂ particles is effective in suppressing the growth of the intermetallic compounds layer. In addition, the shear strength of the soldered joints was improved by larger nano-TiO₂ particle additions, with the peak shear strength occurring at 1.0 wt% of nano-TiO₂ particles into the Sn3.5Ag0.5Cu solder. The fracture mode also changed with increased amounts of nano-TiO₂ particles.     

Effect of deposition angle on fiber axis tilt in sputtered aluminum nitride and pure metal films

We show that the fiber axis orientation in sputtered aluminum nitride (AlN) responds strongly to deposition angle as compared with pure metal films. Fiber axis tilt was measured in films deposited at angles from 0° to 68° from the substrate normal. For pure metal films of Al and Ag, the strong (111) texture has a fiber axis tilt of < 10° from the substrate normal. For pure Nb films, the strong (110) texture also has a tilt of < 10°. In contrast, for films of the compound AlN, the distinct c-axis texture responds strongly to the deposition direction, with the fiber axis tilt almost following the deposition angle.     

Effect of Cu diffusion through Ni on the interfacial reactions of Sn3.5Ag0.75Cu and SnPb solders with Au/Ni/Cu substrate during aging

The effect of Cu diffusion through Ni on the interfacial reactions of Sn3.5Ag0.75Cu (SAC) and SnPb solders with Au/Ni/Cu substrate during aging was investigated in this study. AuSn₄ needle-like intermetallic compound (IMC) formed at the interfaces of both SAC and SnPb solder joints after laser reflow. In SnPb solder joints, a layer-type ternary IMC, (Au,Ni)Sn₄, formed over a thin layer quaternary IMC (Au,Ni,Cu)₃Sn₄ after aging at 150 °C for 4 days, in which Cu came from the Cu pad below the Ni layer through diffusion. This (Au,Ni,Cu)₃Sn₄ IMC evolved into a new kind of quaternary IMC (Au,Ni,Cu)₆Sn₅ with further aging at 150 °C for 8 days because more Cu diffused through Ni and was involved into the IMC formation. For SAC solder joints, needle-like binary AuSn₄ IMC in as-soldered state changed into a layer-type quaternary IMC (Au,Ni,Cu)Sn₄. The quaternary IMC (Au,Ni,Cu)₆Sn₅, which has the same composition as those found in SnPb solder joints, was developed below the (Au,Ni,Cu)Sn₄ layer after aging at 150 °C for 8 days. It was found that Cu diffusion played a key role in the interfacial reaction and compound formation.     

Effects of nano-Al2O3 additions on microstructure development and hardness of Sn3.5Ag0.5Cu solder

This work investigates the effects of nano-Al₂O₃ on the microstructure and microhardness of the Sn3.5Ag0.5Cu composite solder alloy. In comparison with solder without the addition of nano-Al₂O₃ particles, the formation of primary β-Sn phase, the Ag₃Sn phase average size, and the spacing lamellae decreased significantly in the composite solder matrix. In addition, the eutectic areas of the composite solder were wider than that of the Sn3.5Ag0.5Cu solder. This is attributed to the adsorption of nano-Al₂O₃ particles with high surface free energy on the grain surface during solidification. The wettability property was improved by 0.25–0.5 wt.% addition of nano-Al₂O₃ particles into the Sn3.5Ag0.5Cu solder. However, when the nano-Al₂O₃ particles concentration up to over 1.0 wt.% decreased the beneficial influence. Microhardness improved with the addition of nano-Al₂O₃ particles. This improved mechanical property was due to the composite microstructure, which is close to the theoretical prediction from dispersion strengthening theory.