Sn-6Bi-2Ag(Cu, Sb)无铅钎料合金微观组织分析

利用差示扫描量热计 (DSC)测定了Sn 6Bi 2Ag ,Sn 6Bi 2Ag 0 .5Cu ,Sn 6Bi 2Ag 2 .5Sb三种新无铅钎料合金的熔化温度。结果表明 ,少量Cu的加入能降低Sn Bi Ag系无铅钎料合金的熔化温度 ,而Sb的加入使合金的熔化温度升高。利用光学显微镜 (OM )、扫描电子显微镜 (SEM )、能谱分析 (EDX)对合金的微观组织进行了分析与比较 ,钎料合金的微观组织与冷却条件和合金元素的含量有关 ,Sb的加入使析出相的尺寸细化。硬度测定表明Sn Bi Ag(Cu ,Sb)无铅钎料合金的硬度远大于纯Sn的硬度 ,加入少量的Cu(0 .5 % ) ,Sb(2 .5 % )对Sn Bi Ag系钎料合金的硬度影响较小     

合金元素对AgCuZn系钎料合金组织与性能的影响

通过向AgCuZn系钎料合金中添加适量的合金元素Sn,Ni,P,研究了不同元素含量的Sn,Ni,P对AgCuZn系无镉钎料组织性能的影响.结果表明,随着Sn元素含量的增加,钎料的润湿铺展性能整体呈上升趋势;P元素的加入可以降低液态钎料与试件间的表面张力,改善钎料的润湿性和流动性.显微组织分析表明,AgCuZn系钎料合金微观组织主要由富Cu相、CuZn化合物相、Cu5.6Sn化合物相、Cu40.5 Sn11化合物相和Ag的析出相组成,AgCuZn钎料合金中加入Sn元素后生成粗大的树枝晶,使钎料脆性增大;钎料合金中加入Ni元素,生成灰黑色的Ni3P化合物相,微观组织细化;P元素的加入生成灰色的Cu3P化合物相.     

Ni/P/Ce元素对SnAgCu无铅钎料性能和组织的影响

研究添加微量单一Ni、P或稀土Ce元素对Sn3.0Ag0.5Cu(质量分数, %)无铅钎料熔化温度、润湿性能、时效前后钎焊接头的剪切强度和显微组织的影响。结果表明：单一Ni、P和稀土Ce元素的添加,对Sn3.0Ag0.5Cu钎料合金的熔化温度影响很小;P元素的加入能够增大合金的润湿力,缩小润湿时间。加入单一的Ni或稀土Ce元素对合金的润湿性能和接头时效前的剪切强度影响不大,但能够很好地抑制高温时效引起的接头剪切强度的下降。此外,P 元素的添加明显地改善了合金的抗氧化性能,但稀土Ce元素的添加对其有所恶化。这些性能的改变与微量Ni、P或稀土Ce元素对其显微组织的影响有关     

合金元素对Cu-P系钎料性能影响的研究现状

综合介绍了国内外对Cu-P系钎料的研究现状,阐述了为改善Cu-P系钎料的不足之处,研究者通过添加合金元素(特别是Ag,Sn,Ni,Si,Zr,Sb,B以及各种稀土元素等)改善与提高Cu-P系钎料熔化特性、润湿性能、力学性能、显微组织等研究成果。研究表明:Ag,Sn和Ni是降低铜磷钎料熔化温度的最有效元素,而稀土元素Si,Zr,Sb的添加则能显著改善铜磷钎料的润湿性及塑韧性,且随着合金元素的添加钎缝的组织和性能也得到明显改善。同时简述了在研究过程中遇到的问题以及相应的解决方法,为后续的研究提供理论参考,并对Cu-P系钎料未来的发展趋势进行了展望。     

电真空器件用金银锗钎料研制

研究了Au-Ag-Ge系列合金的熔化特性、加工性能以及钎焊性能。结果表明,在Au-12Ge合金中加入Ag元素,可以提高合金的熔化温度,但是仍不能满足使用要求。Au-52Ag-6Ge合金熔化温度为566～586℃,采用冷轧制+真空退火工艺可将合金加工制备为0. 10 mm厚的带材,清洁性、溅散性和铺展性能良好,可以与AgCu28共晶钎料、Ag Cu In钎料、AgCuInSn钎料形成四级梯度钎料,满足真空电子器件封接需求。     

低银无镉Ag-Cu-Zn钎料的合金化改性

介绍了低银无镉Ag-Cu-Zn系钎料的成分特点和研发思路,采用Sn、P元素对含银21 mass%的Ag-Cu-Zn系钎料进行合金化,讨论了Sn、P元素含量对钎料熔化温度及显微组织的影响。结果表明,随Sn含量增加,钎料的熔化温度可持续下降,同时晶内及晶界相的Sn固溶量增大,钎料趋于硬脆。微量P的添加能显著降低银钎料的熔点,(Sn+P)低水平复合添加可在满足熔化特性的同时,避免由于过量Sn固溶导致的加工成型困难,有利于钎料的实用生产。     

Ge对SnAgCu/Cu钎焊界面结构的影响

化学元素周期表中Ge与Sn相邻,同为第Ⅳ主族元素,物理与化学性能近似.在无铅钎料Sn2.5Ag0.7Cu中添加少量Ge元素(质量分数分别为0.25%,0.5%,0.75%,1.0%),制作了钎焊界面.用扫描电子显微镜(SEM)对界面显微组织与形貌做了观察分析,用Auto CAD软件测量了金属间化合物(IMC)厚度,用能谱仪(EDX)分析了界面成分.结果表明,加入Ge元素后界面IMC的形貌仍为贝壳状,但该组织显示出长大趋势;经150℃/100 h老化后,界面变得更加平缓、整齐.钎料含Ge时,未老化界面IMC层厚度更大,经150 ℃/100 h老化后,IMC层增厚率要小.Ge元素的加入抑制老化过程中界面金属间化合物Cu6Sn5向Cu3Sn的转变和其自身的长大.     

Ag元素含量对SnAgCuX无铅钎料性能的影响

分析了SnAgCuX系无铅钎料中Ag异元素含量的变化对熔化温度、润湿性能的影响,同时研究了时效前和高温时效后钎焊接头的抗剪强度和显微组织,其中X包含Ni,P和Ce三种元素.结果表明,添加微量X元素能够在一定程度上弥补snAgCu钎料中Ag元素含量的降低引起的性能下降.X元素的添加对SnAgCu钎料的熔化温度影响不大,但能改善钎料合金的润湿性能,提高钎焊接头的抗剪强度,并抑制时效引起的接头强度下降.这与微量X元素的添加改善了钎料的显微组织和金属间化合物的形貌有很大的关系.     

添加微量稀土对SnBi基无铅钎料显微组织和性能的影响

研究了添加微量稀土对Sn58Bi基无铅钎料熔化温度、润湿性能、钎焊接头强度、高温时效前后IMC厚度的变化和显微组织的影响,并与添加一定量Ag对Sn58Bi钎料的试验结果做了比较.试验所用钎料为Sn58Bi,Sn58Bi0.5Ag,Sn58Bi0.1RE和Sn58Bi0.5Ag0.1RE,添加稀土为Ce基混合稀土.试验结果表明,添加微量稀土不仅抑制了Sn58Bi钎料高温时效引起的IMC的生长,而且细化了显微组织;微量稀土添加对钎料熔化温度没有明显影响,但能显著改善Sn58Bi钎料的润湿性能和接头强度,而且改善的程度优于添加微量Ag对Sn58Bi钎料的作用.     

锡镀层对BAg50CuZn钎料性能的影响

以BAg50CuZn钎料为研究对象,在其表面电镀锡,借助扫描电镜(SEM)观察锡镀层的表面形貌,采用差热分析仪(differential scanning calorimetry,DSC)和润湿试验炉分析锡镀层对合金钎料熔化温度和润湿性能的影响,并对镀覆锡后合金钎料的成分进行了讨论.结果表明,随着钎料表面镀覆Sn元素含量增加,合金钎料的DSC吸热峰向左偏移、熔化温度降低,钎料的润湿铺展性能呈上升趋势.在镀覆Sn元素含量为4.8%(质量分数)时,合金钎料表面锡镀层平整、致密,钎料的铺展面积最大,为236 mm2.镀覆元素Sn后的钎料中,Ag,Cu,Zn元素含量均减少,元素含量降低幅度大小顺序依次为Cu,Ag,Zn.     

Evolution of Ag3Sn at Sn-3.0Ag-0.3Cu-0.05Cr/Cu joint interfaces during thermal aging

The intermetallic compounds (IMC) in the solder and at the interface of Sn-3.0Ag-0.5Cu (SAC)/Cu and Sn-3.0Ag-0.3Cu-0.05Cr (SACC)/Cu joints were investigated after isothermal aging at 150 °C for 0, 168 and 500 h. Different shaped Ag₃Sn phases were found near the IMC layer of the latter joint. Interestingly, fine rod-shaped and branch-like Ag₃Sn were detected near the interface after soldering and long Ag₃Sn changed into shorter rods and small particles during aging. It is investigated that the Cr addition and thermal aging have effect on the evolution of Ag₃Sn morphologies and it is controlled by interfacial diffusion. Energy minimization theory and the redistribution of elements are used to explain the morphological evolution of Ag₃Sn. Small Ag₃Sn particles were also found on the IMC layer after aging, unlike the large Ag₃Sn at that of SAC/Cu joints. In conclusion, a favorable morphology of the joint interface leads to better bonding properties for SACC/Cu joints against thermal aging than that for SAC/Cu.     

62Sn36Pb2Ag钎料中Ag元素对AgCu/SnPbAg/CuBe焊缝性能的影响

分别采用62Sn36Pb2Ag钎料和63Sn37Pb共晶钎料焊接AgCu合金块和CuBe合金片进行试验,对比分析两种钎料形成的焊缝性能和显微组织结构,阐述了62Sn36Pb2Ag钎料中Ag元素的存在对AgCu/SnPbAg/CuBe焊缝性能的影响机制.结果表明,62Sn36Pb2Ag钎料中的Ag元素对于润湿铺展状态的改...     

Solid-liquid reactions: The effect of Cu content on Sn-Ag-Cu interconnects

The impact of copper content on the Sn-Ag-y%Cu (Ag=constant=3.5; y=0.0, 0.5, 1.0, and 2.0) interconnects was investigated in this study. The copper content and solid-liquid (S-L) reactions were used as inputs, and the outputs were the interfacial microstructure evolution and joint macro-performance. Surface microetching microscopy, cross-section microscopy, energy-dispersive x-ray analysis, shear test, and differential scanning calorimetry were used in the studies. It was discovered that as-soldered Sn-Ag-y%Cu interconnects could have different interfacial microstructures depending on copper content; no Ag₃Sn plates were observed for any alloy groups. After the S-L reactions, Ag₃Sn plates occurred for all groups. The magnitude of the Ag₃Sn plate growth depended on copper content. This and other effects of copper content on Sn-Ag-Cu interconnects are discussed in this article.     

镀锡AgCuZnSn钎料熔化特性的热力学分析

以BAg50CuZn钎料为基材,采用电镀热扩散组合工艺制备了镀锡AgCuZnSn钎料。为了揭示镀锡银钎料的热力学特性,借助差示扫描量热仪(DSC)测定了镀锡银钎料的熔化温度,运用热分析动力学中的非等温微分法和积分法分析了镀锡银钎料的相变热力学特性,并利用金相显微镜和X射线衍射仪(XRD)对钎料熔化后润湿界面的显微组织和物相进行了分析。研究表明,随着Sn含量升高,在吸热峰镀锡银钎料由固态向液态转变的温度区间变窄,非等温微分法和积分法得到的钎料相变活化能均逐渐增大。在Sn含量为7.2%时,镀锡银钎料的相变活化能和指前因子最大,分别为555.56kJ/mol、1.41×10~(32),此时镀锡银钎料相变速率方程的表达式为:k=1.41×10~(32)exp(-5.56×10~5/RT)。7.2%Sn含量的镀锡银钎料在304不锈钢表面熔化后,润湿界面组织主要由Ag相、Cu相、CuZn相、Cu_5Zn_8相、Cu_(41)Sn_(11)相、Ag_3Sn相组成。     

Effects of Sb,Sm, and Sn additions on the microstructure and mechanical properties of Mg-6Al-1.2Y-0.9Nd alloy

The microstructure and mechanical properties of Mg-6Al-1.2Y-0.9Nd magnesium alloy with Sb, Sm, or Sn addition were investigated through X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results show that small amounts of Sb, Sm, and especially Sn can refine the grains of the alloy. High melting point Sb₃Y₅, Al₂Sm, and Nd₅Sn₃ intermetallic compounds can be formed respectively when Sb, Sm, and Sn are added to the alloy. Sb and Sm can improve the tensile strength of the alloy at ambient and elevated temperatures. The tensile strength of the alloy with Sm addition is the highest at 293 and 423 K. However, the tensile strength of the alloy with Sn addition is the highest at 448 K.     

Reaction properties and interfacial intermetallics for Sn−xAg−0.5Cu solders as a function of Ag content

Wetting and interfacial reactions were investigated for Sn−xAg−0.5Cu alloys, in which the Ag content had a variation from x=1.0 to x=4.0. Differential scanning calorimetry (DSC) was used to investigate the range of the melting temperature and the solidification temperature by measuring the endothermic and the exothermic heat flow, respectively. Low Ag contents increased the melting temperature ranges and deteriorated the wetting properties such as zero cross time and wetting force measured at two seconds. The extent of undercooling increased and the thickness of intermetallic compounds (IMC) decreased as the Ag content decreased. As the Ag content decreased, the initial IMC thickness decreased due to the large undercooling and, during the solid aging at 170°C, the IMC growth slightly decelerated because of the small diffusion coefficient. For the application of good drop shock reliability, Sn−Ag−Cu solder of low Ag content should be beneficial due to the restraint of the IMC growth (Cu₆Sn₅ and Cu₃Sn) and of the coarse plate-like IMC (Ag₃Sn).     

Improving p-type thermoelectric performance of Mg2(Ge,Sn) compounds via solid solution and Ag doping

Mg₂X (X = Si, Ge, and Sn) compounds have attracted increasing attention owing to their promising thermoelectric properties and “green” constituent elements. While most studies to date have been on n-type Mg₂(Si,Sn) solid solutions, we herein report Ag-doping study in Mg₂(Ge,Sn) solid solutions to pursue higher p-type performance. Two series of samples, Mg₂Ge_1−xSn_x and Mg_2−yAg_yGe_0.4Sn_0.6, were prepared by melting in evacuated Ta tubes, followed by hot pressing, and the thermoelectric properties of the solid solutions were investigated from room temperature to 723 K. An n- to p-type crossover in the Seebeck coefficient was observed for Mg₂Ge_0.4Sn_0.6 and Mg₂Ge_0.2Sn_0.8 at elevated temperatures. To enhance p-type performance, we doped Ag in Mg₂Ge_0.4Sn_0.6 that exhibited lowest thermal conductivity among the Mg₂(Ge,Sn) solid solutions. It was found that (1) p-type behavior has been established in Mg_2−yAg_yGe_0.4Sn_0.6 (y = 0.005, 0.01, 0.02, 0.04) samples in the entire temperature range studied; and (2) the electrical conductivity increased with increasing Ag content until reaching the solution limit ∼0.02. As a result, a dimensionless figure of merit ZT ∼0.38 is attained for Mg_1.98Ge_0.4Sn_0.6Ag_0.02 at 675 K, which is one of the highest reported values in p-type Mg₂X compounds.     

Characterization of Sn and Si nanocrystals embedded in SiO2 matrix fabricated by magnetron co-sputtering

Sn and Si nanocrystals were prepared by depositing Sn-Si-rich SiO₂ films using a co-sputtering process and a subsequent annealing. The microstructure and optical properties of Sn and Si nanocrystals were characterized by scanning electron microscopy (SEM), Raman spectra, X-ray diffraction and photoluminescence spectra. The crystallization of Sn has started at the annealing temperature of 400 °C, and was accomplished at 700 °C. However, the phase of amorphous Si starts to transform into nanocrystal Si when the annealing temperature is higher than 700 °C. These results illustrate that Sn existence as an element may played an important role in lowering the crystallization temperature of Si, and the crystallization rate of Si will be enhanced when Sn atom serves as the nucleation centre. Because quantum confinement effects are expected at relatively large radius for nanocrystal Sn, the redshift of high-energy PL peak may result from quantum confinement effects of nanocrystal Sn. However, the low-energy PL peak may be attributed to defects.     

Scaling effect on Ag3Sn growth behaviours in micro-joints for flip chip assemblies

The scaling effect on Ag₃Sn growth behaviours in Sn–3.0Ag–0.5Cu (SAC305) micro-joints of flip chip assemblies was investigated using thermal shock (TS) tests. After assembly reflow, the large plate-like Ag₃Sn compounds only emerged from the Cu interface of small joints, which was strongly related with a higher local Ag concentration in the remaining solder. During TS cycling, the growth of Ag₃Sn grains exhibited comparatively more pronounced growth in the solder matrix of small joints, due to the stronger strain-enhanced coarsening induced by more cycle stress and strain. Coarsening kinetic models based on TS experiments were employed to predict Ag₃Sn growth, the kinetic constants N were determined to clarify the correlation of the joints scaling and Ag₃Sn coarsening in depth.     

Observations of nucleation catalysis effects during solidification of SnAgCuX solder joints

While modification of a strong (high Cu) Sn-Ag-Cu (SAC) solder alloy with a substitutional alloy addition (X=Co, Fe, Zn, and Ni) for Cu has been demonstrated to enhance solder joint strength and ductility after aging at 150°C for 1,000 h, control of the as-solidified SAC+X solder joint microstructure is also needed to inhibit under cooling and nucleation of brittle pro-eutectic phases (e.g., Ag₃Sn). Bulk undercooling measurements of SAC+X alloys and microstructural analysis of SAC+X solder joints were used to rank the effectiveness and consistency of low-level (X < 0.15 wt.%) substitutional additions to a base SAC composition, Sn-3.5Ag-0.95Cu (wt.%). This SAC composition was selected to favor thermodynamically the nucleation of pro-eutectic Cu₆Sn₅ over that of Ag₃Sn and the formation of an enhanced ternary eutectic fraction in the joint microstructure, while retaining a pasty range that is only 3°C. Using differential scanning calorimetry with sample pans that serve as either inert (aluminum) or actively wetting (copper) substrates, reflow cycles were studied that simulated surface mount (1.5°C/s) and ball-grid array (0.17°C/s) cooling rates. Of the SAC+X solders tested with copper pans, X = Zn appeared to be most effective and consistent, providing catalytic enhancement of the nucleation temperature for even the minimum concentration (0.05 wt.%) and lowest cooling rate.