共查询到20条相似文献,搜索用时 10 毫秒
1.
E.S. Vasilyeva O.V. Tolochko B.K. Kim D.W. Lee D.S. Kim 《Microelectronics Journal》2009,40(4-5):687-691
Crystalline tungsten disulphide nanoparticles were successfully synthesized by the chemical vapor condensation (CVC) method. The process performed as decomposition of tungsten hexacarbonyl over sulphur vapor in inert gas flow, where WS2 nanoparticles were synthesized by direct reaction between as formed pure tungsten nanoclusters and sulphur vapor. Influence of experimental parameters on shape, size distribution, structure and phase composition of nanoparticles were evaluated by transmission and scanning electron microscopy and X-ray diffraction analysis. The produced nanoparticles have closely spherical shape with the mean size in the range 20–70 nm in diameter dependently of process parameters. Nested “onion-like” structure of nanoparticles was observed. The mean value of interlayer distance in the {0 0 0 1} direction, is about 0.6358±0.031 nm. Due to nanodimensional size, physical properties and layered structure tungsten disulphide nanoparticles have great potential as a solid lubricant material. 相似文献
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In prior work, we showed that eutectic Sn-Pb solder joints exhibit superplastic behavior after rapid solidification. Further
examples of superplasticity in nominally air-cooled solder joints are reported in this study of three low-melting point alloys:
40In-40Sn-20Pb (wt. %), eutectic 52In-48Sn, and 43Sn-43Pb-14Bi, which were creep-tested in shear at 20°, 65°, and 90° C. The
test results indicate that above 65° C, the indium-containing solders have stress exponents between 2.4 to 2.9, a possible
overall shear strains of 500%, and an absence of primary creep; at 90° C, 43Sn-43Pb-14Bi solder has a stress exponent close
to 2.3. Optical microstructures of the three solders are presented; they help to explain the superplastic behavior. 相似文献
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为了获得低熔点、折射率各向异性(Δn)大的快速响应向列相液晶材料,高Δn值的液晶混合体系中需要加入熔点在50℃以下、Δn大于0.35的双环类液晶组分,以使快速响应向列相液晶材料满足室温工作的要求。本文合成了异硫氰基含氟二苯乙炔类液晶化合物;一方面由于在分子苯环侧位引入F原子,减小分子间作用力,使化合物的熔点下降;另一方面在两个苯环间引入三键、分子末端接入异硫氰基极性基团,增加了分子的共轭性,提高了目标化合物的Δn值。获得了熔点分别为31℃和50℃、Δn为0.39和0.40,这两种低熔点化合物与目前已具有的毫秒级快速响应向列相液晶化合物混合,可使其熔点低至10℃以下。 相似文献
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Nano-sized, nonreacting, noncoarsening oxide dispersoids have been incorporated into solder alloys to create a new, improved
solder structure with an ultrafine grain size of ∼200–500 nm. The new solders exhibit significantly enhanced creep resistance
combined with increased strength. The well-known thermal instability problem with ultrafine-grained structure appears to have
been overcome in these solder alloys and the microstructure was seen to be quite stable upon high temperature exposure (e.g.
120°C). This is attributed to the presence of very fine dispersoid particles which impede grain boundary sliding and dislocation
movement. The dispersions are seen to have a profound effect on the mechanical deformation characteristics of the solders
with respect to creep. As much as three orders of magnitude reduction in the steady state creep rate has been achieved. The
new solders also exhibit improved ductility under high strain rate deformation and improved strength (4–5 times higher tensile
strength) at low strain rates. It is demonstrated that with a dispersion of TiO2 particles, the Pb-Sn eutectic solder with a melting point of 183°C can be made more creep-resistant than the 80Au-20Sn eutectic
solder with a much higher melting point of 278°C. The new creep-resistant solders can be useful for optical and optoelectronic
packaging in which dimensional stability of the assembled structure is essential. 相似文献
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研制了一种厚膜片电阻用低熔点玻璃保护浆料。这种浆料由玻璃粉、颜料及有机载体按一定比例混合而成。烧结温度约600℃,黏度180~240Pa·s,颗粒度不大于3μm,被封电阻烧成后,平均阻值变化率为0.65%。 相似文献
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For the highly reliable interconnection in a micro-packaging technology requiring an excellent electrical and mechanical performance, the new anisotropic conductive adhesive (ACA) system with a low melting point solder was designed and characterized. An optimum flip-chip bonding cycle considering the chemo-rheological properties of a polymer matrix and solder was proposed. The bonding mechanism of the new ACA system was experimentally observed by the optical microscope. The electrical properties such as electrical resistance of about 5.6 mΩ and current density of 10,000 A/cm2 were measured by the 4-point probe test. The measured shear strength was 304 MPa after bonding process.Electrical and mechanical performances were measured and compared before and after a pressure cooker test (PCT). In order to get a more stable ACA system during processing, the polymer matrix mixed with a reductant and a low melting point solder powder will be continuously developed in the near future. 相似文献
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Chalcopyrite-type CulnSe2 nanoparticles are successfully prepared by using In2Se3 nanoparticles as a precursor reacted with copper chloride (CuCl) solution via a phase transformation process in low temperature. The reaction time is a key parameter. After the reaction time increasing from 0.5 h to 8 h, In2Se3 and CuCl react with each other gradually via phase transformation into CuInSe2 without any intermediate phase. The crystalline structure and morphology of the CuInSe2 nanoparticles are characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The diameter of CuInSe2 nanoparticles with good dispersibility ranges from 10 nm to 20 nm. The band gap of the CulnSe2 nanoparticles is 1.04 eV calculated from the ultraviolet-visible (UV-VIS) spectrum. 相似文献
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Characterization of polymer matrix and low melting point solder for anisotropic conductive film 总被引:1,自引:0,他引:1
The chemo-rheological mechanisms of a polymer matrix and a low melting point solder for an anisotropic conductive film (ACF) have been characterized. For the material characterization of the polymer matrix and solder, a differential scanning calorimetry (DSC) and a dynamic mechanical analyzer (DMA) experiments were conducted. The conversion and viscosity of the polymer matrix was observed by DSC and DMA, respectively. In order to control the curing conditions such as the reaction temperature and time of polymer matrix, the adequate amount of catalyst was used. The compatibility between the viscosity of a polymer matrix and a melting temperature of solder was characterized to optimize the processing cycle. The reductant was also added to remove the oxide layer performed on the surface of solder in the air environment. Based on these chemo-rheological phenomena of the polymer matrix and solder, the optimum polymer system and its processing cycle were designed for the high performance and reliability in the electrical interconnection system. 相似文献
12.
Sn-3.5Ag-0.5Cu nanoparticles were synthesized by chemical precipitation with NaBH4. By using x-ray diffraction and transmission and scanning electron microscopy, the microstructural characteristics of particle
growth were evaluated. The results indicated that the primary particles after precipitation were (Ag,Cu)4Sn, with a size of 4.9 nm. (Ag,Cu)4Sn was transformed into (Ag,Cu)3Sn, when the total amount of Sn contributed from both (Ag,Cu)4Sn and Sn covering the (Ag,Cu)4Sn overtook that of (Ag,Cu)3Sn. The final particle size of polycrystalline particles was 42.1 nm owing to the depletion of Sn atoms in the solution. Nucleation
and growth mechanisms of Sn-3.5Ag-0.5Cu nanoparticles are also discussed and proposed. 相似文献
13.
Kyoung-Sik Moon Jiali Wu Wong C.P. 《Components and Packaging Technologies, IEEE Transactions on》2003,26(2):375-381
With the driving force of "green" revolution in the electronics industry, tremendous efforts have been made in pursuing lead-free alternatives. Although lately lead-free alloys have drawn a lot of attention, their technical weaknesses, such as high processing temperature, poor wetting and high surface tension, limit their applications on the thermally sensitive, flexible, nonsolderable substrates and the ultra-fine pitch size flip chip interconnection. Conventional isotropically conductive adhesives (ICAs) have been used widely in surface mount and die-attach technologies for electrical interconnection and heat dissipation. The low temperature processing of ICAs is one of the major advantages over lead-free solders, which brings a low system stress, simple manufacture process and the like. In order to enhance the contact resistance of ICAs, the low melting point alloy (LMA) incorporating technology has been developed by our group. In this paper, LMA fusing methods were studied, since nonfused LMA in ICAs after a curing process can adversely affect the physical property and contact resistance stability. A differential scanning calorimeter (DSC) was used for the basic examination of depleting rate of LMAs in the typical ICAs. The cross-sectional morphology, LMA distribution and intermetallic compound were investigated by a scanning electron microscope (SEM). In addition, contact resistance for the ICA formulation incorporated with LMAs under elevated temperature and humidity was evaluated. 相似文献
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This paper describes a concept of controlling operation time of a high-density packaging using a phase change material (PCM). A low cost alloy, which is composed of Bi/Pb/Sn/In and having melting point less than 343 K, was used as the PCM. Thermal experiments using the alloy were carried out and it was confirmed that the substrate back surface temperature could be kept constant at the melting temperature of the PCM for several minutes by thermal absorption, while the PCM phase changed from its original solid state into the liquid state. Also, in the present work, it was confirmed that thermal network method is practically useful for the thermal design of a package with a PCM. 相似文献
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该文提出一种新的混沌信号降噪方法微扰法,并且给出了微扰法的一个具体实例算法梯度微扰法。该文还对用梯度微扰法进行混沌信号降噪的效果进行了实验研究。实验结果表明,梯度微扰法能够在低信噪比时得到很好的降噪效果。文中还对梯度微扰法的参数选择问题进行了实验研究。 相似文献
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A low viscosity epoxy resin with carboxylic acid-based novel reductants was introduced to improve the process ability and reliability of an anisotropic conductive adhesive (ACA) resin with a low melting point alloy (LMPA) filler system. The curing degree of the ACA resin and the melting of the LMPA filler were investigated using differential scanning calorimetry (DSC) conducted in the dynamic mode in order to control the curing conditions such as the reaction temperature and a melting temperature of solder. The temperature-dependent viscosity characteristics of the ACA resin were investigated using a rheometer. The compatibility between the viscosity of a polymer matrix and a melting temperature of solder was characterized to optimize the processing cycle. Three different types of carboxyl acid-based reductants were added to remove the oxide layer on the surfaces of the filler particles and the conductive pad. Good wetting properties were achieved between the LMPA filler and the Cu pad in the epoxy resin using these carboxylic acid-based reductants. 相似文献
18.
M. MC Cormack I. Artaki S. Jin A. M. Jackson D. M. Machusak G. W. Kammlott D. W. Finley 《Journal of Electronic Materials》1996,25(7):1128-1131
Wave soldering with low solid fluxes at temperatures as low as 175°C on test boards with a Cu/Imidazole surface finish has
been shown to be feasible using a Pb-free, Bi-45%Sn-0.33%Ag solder that melts at temperatures of ∼140∼145°C. Other surface
finishes such as Pd/Ni, Au/Ni, and Bi exhibit unacceptable soldering at temperatures below 210°C. Intermediate in performance
are Sn surface finishes, which exhibit acceptable soldering at 190°C, but not at 175°C. Acceptable joints wave soldered on
Cu/Im finishes passed class I/II inspection criterion and exhibited pull strengths in excess of the ultimate strength of the
component leads. 相似文献
19.
E. Belas R. Grill J. Franc L. Turjanska I. Turkevych P. Moravec P. Höschl 《Journal of Electronic Materials》2003,32(7):752-755
A new experimental setup for the investigation of electrical conductivity (σ) in liquid and solid CdTe was built for a better
understanding of the properties near the melting point (MP). The temperature dependence of σ was studied, within the interval
1,050–1,130°C, at defined Cd-partial pressures 1.3–1.6 atm, with special attention to the liquid-solid phase transition. We
found that the degree of supercooling decreases with increasing Cd overpressure and reaches the lowest value at 1.6 atm without
change of the melting temperature during heating. 相似文献