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1.
稀土改性的Sn-58Bi低温无铅钎料 总被引:1,自引:0,他引:1
研究了微量稀土对Sn-58Bi低温钎料的改性作用.试验添加质量分数为0.1 ?组混合稀土的无铅材料,并对比Sn-58Bi和Sn-58Bi0.5Ag合金.观察了钎料显微组织的变化并做了定量分析,采用DSC测试了钎料的熔化温度,同时测量了钎料的润湿性能、接头强度与硬度.结果表明,微量稀土添加细化了Sn-58Bi钎料合金的显微组织,对钎料的熔化温度几乎没有影响,能显著改善Sn-58Bi钎料的润湿性能和接头剪切强度,而且改善的程度优于添加微量Ag对Sn-58Bi钎料的作用. 相似文献
2.
Microstructure, solderability, and growth of intermetallic compounds of Sn-Ag-Cu-RE lead-free solder alloys 总被引:4,自引:0,他引:4
C. M. T. Law C. M. L. Wu D. Q. Yu L. Wang J. K. L. Lai 《Journal of Electronic Materials》2006,35(1):89-93
The near-eutectic Sn-3.5 wt.% Ag-0.7 wt.% Cu (Sn-3.5Ag-0.7Cu) alloy was doped with rare earth (RE) elements of primarily Ce
and La of 0.05–0.25 wt.% to form Sn-3.5Ag-0.7Cu-xRE solder alloys. The aim of this research was to investigate the effect
of the addition of RE elements on the microstructure and solderability of this alloy. Sn-3.5Ag-0.7Cu-xRE solders were soldered
on copper coupons. The thickness of the intermetallic layer (IML) formed between the solder and Cu substrate just after soldering,
as well as after thermal aging at 170°C up to 1000 h, was investigated. It was found that, due to the addition of the RE elements,
the size of the Sn grains was reduced. In particular, the addition of 0.1wt.%RE to the Sn-3.5Ag-0.7Cu solder improved the
wetting behavior. Besides, the IML growth during thermal aging was inhibited. 相似文献
3.
Law C.M.T. Wu C.M.L. Yu D.Q. Li M. Chi D.Z. 《Advanced Packaging, IEEE Transactions on》2005,28(2):252-258
Rare earth (RE) elements, primarily La and Ce, were doped in Sn-Zn solder to improve its properties such as wettability. The interfacial microstructure evolution and shear strength of the Sn-9Zn and Sn-9Zn-0.5RE (in wt%) solder bumps on Au/Ni/Cu under bump metallization (UBM) in a ball grid array (BGA) were investigated after thermal aging at 150 /spl deg/C for up to 1000 h. In the as-reflowed Sn-9Zn solder bump, AuSn/sub 4/ intermetallic compounds (IMCs) and Au-Zn circular IMCs formed close to the solder/UBM interface, together with the formation of a Ni-Zn-Sn ternary IMC layer of about 1 /spl mu/m in thickness. In contrast, in the as-reflowed Sn-9Zn-0.5RE solder bump, a spalled layer of Au-Zn was formed above the Ni layer. Sn-Ce-La and Sn-Zn-Ce-La phases were found near the interface at positions near the surface of the solder ball. Upon thermal aging at 150 /spl deg/C, the concentration of Zn in the Ni-Zn-Sn ternary layer of Sn-9Zn increased with aging time. For Sn-9Zn-0.5RE, the Au-Zn layer began to dissolve after 500 h of thermal aging. The shear strength of the Sn-9Zn ball was decreased after the addition of RE elements, although it was still higher than that of the Sn-37Pb and Sn-36Pb-2Ag Pb-bearing solders. The fracture mode of the Sn-9Zn system was changed from ductile to partly brittle after adding the RE elements. This is mainly due to the presence of the brittle Au-Zn layer. 相似文献
4.
The Sn-0.7%Cu alloy has been considered as a lead-free alternative to lead-tin alloys. In this work, various small amounts
of rare earth (RE) elements, which are mainly Ce and La, have been added to the Sn-0.7%Cu alloy to form new solder alloys.
It was found that the new alloys exhibit mechanical properties superior to that of the Sn-0.7%Cu alloy. In particular, the
addition of up to 0.5% of RE elements is found to refine the effective grain size and provide a fine and uniform distribution
of Cu6Sn5 in the solidified microstructure. Tensile, creep, and microhardness tests were conducted on the solder alloys. It was found
that significant improvements of the tensile strength, microhardness, and creep resistance were obtained with RE element addition.
Upon aging at 150°C for 20 h, the microstructure of Sn-Cu-RE is more stable than that of the Sn-Cu alloy. 相似文献
5.
Effects of Ce Addition on the Microstructure and Mechanical Properties of Sn-58Bi Solder Joints 总被引:1,自引:0,他引:1
The effects of a rare-earth element on the microstructure, mechanical properties, and whisker growth of Sn-58Bi alloys and
solder joints in ball grid array (BGA) packages with Ag/Cu pads have been investigated. Mechanical testing indicated that
the elongation of Sn-58Bi alloys doped with Ce increased significantly, and the tensile strength decreased slightly, in compar- ison
with undoped Sn-58Bi. In addition, the growth of both fiber- and hillock-shaped tin whiskers on the surface of Sn-58Bi-0.5Ce
was retarded in the case of Sn-3Ag-0.5Cu-0.5Ce alloys. The growth of interfacial intermetallic compounds (IMC) in Sn-58Bi-0.5Ce
solder joints was slower than that in Sn-58Bi because the activity of Ce atoms at the interface of the Cu6Sn5 IMC/solder was reduced. The reflowed Sn-58Bi and Sn-58Bi-0.5Ce BGA packages with Ag/Cu pads had a ball shear strength of
7.91 N and 7.64 N, which decreased to about 7.13 N and 6.87 N after aging at 100°C for 1000 h, respectively. The reflowed
and aged solder joints fractured across the solder balls with ductile characteristics after ball shear tests. 相似文献
6.
In this study, the effect of adding 0.5 wt.% and 1 wt.% In and Ni to Sn-58Bi solder on intermetallic compound (IMC) layers at the interface and the microstructure of the solder alloys were investigated during reflow and thermal aging by scanning electron microscopy and electron probe micro-analysis. The results showed that the addition of minor elements was not effective in suppressing the IMC growth during the reflow; however, the addition of 0.5 wt.% In and Ni was effective in suppressing the IMC layer growth during thermal aging. The thickening kinetics of the total IMC layer was analyzed by plotting the mean thickness versus the aging time on log–log coordinates, and the results showed the transition point from grain boundary diffusion control to a volume diffusion control mechanism. The results also showed that the minor addition of In can significantly suppress the coarsening of the Bi phase. 相似文献
7.
In the current research, trace rare earth (RE) element Y was incorporated into a promising lead-free solder, Sn3.8Ag0.7Cu,
in an effort to improve the comprehensive properties of Sn3.8Ag0.7Cu solder. The range of Y content in Sn3.8Ag0.7Cu solder
alloys varied from 0 wt.% to 1.0 wt.%. As an illustration of the advantage of Y doping, the melting temperature, wettability,
mechanical properties, and microstructures of Sn3.8Ag0.7CuY solder were studied. Trace Y additions had little influence on
the melting behavior, but the solder showed better wettability and mechanical properties, as well as finer microstructures,
than found in Y-free Sn3.8Ag0.7Cu solder. The Sn3.8Ag0.7Cu0.15Y solder alloy exhibited the best comprehensive properties compared
to other solders with different Y content. Furthermore, interfacial and microstructural studies were conducted on Sn3.8Ag0.7Cu0.15Y
solder alloys, and notable changes in microstructure were found compared to the Y-free alloy. The thickness of an intermetallic
compound layer (IML) was decreased during soldering, and the growth of the IML was suppressed during aging. At the same time,
the growth of intermetallic compounds (IMCs) inside the solder was reduced. In particular, some bigger IMC plates were replaced
by fine, granular IMCs. 相似文献
8.
Lili Gao Liang Zhang Feng Ji Sheng-lin Yu Guang Zeng 《Microelectronic Engineering》2010,87(11):2025-7059
Recent years, the SnAgCu family of alloys has been found a widely application as a replacement for the conventional SnPb solders in electronic industry. In order to further enhance the properties of SnAgCu solder alloys, alloying elements such as rare earth, Bi, Sb, Fe, Co, Mn, Ti, In, Ni, Ge and nano-particles were selected by lots of researchers as alloys addition into these alloys. Rare earth (RE) elements have been called the ‘‘vitamin” of metals, which means that a small amount of RE elements can greatly enhance the properties of metals, such as microstructure refinement, alloying and purification of materials and metamorphosis of inclusions. In addition, a small amount of Zn addition has the ability to reduce undercooling efficiently and suppress the formation of massive primary Ag3Sn plates, and Bi/Ga has the ability to enhance the wettability of SnAgCu alloys as well as Ni. Moreover, adding Co/Fe/Ge can effectively refine microstructure, modify interfacial Cu-Sn compounds and increase the shear strength of joints with Cu. This paper summarizes the effects of alloying elements on the wettability, mechanical properties, creep behavior and microstructures of SnAgCu lead-free solder alloys. 相似文献
9.
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11.
The mechanical and electrical properties of several Pb-free solder joints have been investigated including the interfacial
reactions, namely, the thickness and morphology of the intermetallic layers, which are correlated with the shear strength
of the solder joint as well as its electrical resistance. A model joint was made by joining two “L-shaped” copper coupons
with three Pb-free solders, Sn-3.5Ag (SA), Sn-3.8Ag-0.7Cu (SAC), and Sn-3.5Ag-3Bi (SAB) (all in wt.%), and combined with two
surface finishes, Cu and Ni(P)/Au. The thickness and morphology of the intermetallic compounds (IMCs) formed at the interface
were affected by solder composition, solder volume, and surface finish. The mechanical and electrical properties of Pb-free
solder joints were evaluated and correlated with their interfacial reactions. The microstructure of the solder joints was
also investigated to understand the electrical and mechanical characteristics of the Pb-free solder joints. 相似文献
12.
An asymmetrical interfacial microstructure was observed at both top and bottom interfaces of Cu/Sn-58Bi/Cu solder joints after isothermal aging at 120°C for different times. The asymmetrical interfacial microstructure resulted from asymmetrical Bi segregation, which was attributed to the density difference between Bi and Sn atoms. Bi atoms were driven to the bottom solder/Cu interface by gravity during the liquid soldering procedure since Bi atoms are more massive than Sn atoms. With increasing aging time, Bi accumulated at the bottom Cu3Sn/Cu interface and the Bi segregation enhanced Cu6Sn5 intermetallic compound growth, blocked Sn transport to the Cu3Sn intermetallic compound, and facilitated growth of the Cu6Sn5, based on the measured thicknesses of intermetallic compounds (including Cu6Sn5 and Cu3Sn) at both bottom and top interfaces for Cu/Sn-58Bi/Cu sandwich joints under the same aging process. 相似文献
13.
Effects of Ce and La Additions on the Microstructure and Mechanical Properties of Sn-9Zn Solder Joints 总被引:1,自引:0,他引:1
The effects of rare-earth elements on the microstructure and mechanical properties of Sn-9Zn alloys and solder joints in ball
grid array packages with Ni/Au(ENIG) surface finishes have been investigated. Metallographic observations showed that (Ce0.8Zn0.2)Sn3 and (La0.9Zn0.1)Sn3 intermetallic compounds appeared in the solder matrix of Sn-9Zn-0.5Ce and Sn-9Zn-0.5La alloys, respectively. Both fiber-
and hillock-shaped tin whiskers were inhibited in the Sn-9Zn-0.5Ce solder, while tin fibers were still observed on the surface
of oxidized (La0.9Zn0.1)Sn3 intermetallics in Sn-9Zn-0.5La after air exposure at room temperature. Mechanical testing indicated that the tensile strength
of Sn-9Zn alloys doped with Ce and La increased significantly, and the elongation decreased, in comparison with the undoped
Sn-9Zn. The bonding strengths of the as-reflowed Sn-9Zn-0.5Ce and Sn-9Zn-0.5La solder joints were also improved. However,
aging treatment at 100°C and 150°C caused degradation of ball shear strength in all specimens. During the reflowing and aging
processes, AuZn8 intermetallic phases appeared at the interfaces of all solder joints. In addition, Zn-rich phases were observed to migrate
from the solder matrix to the solder/pad interfaces of the aged specimens. 相似文献
14.
Weimin Xiao Yaowu Shi Yongping Lei Zhidong Xia Fu Guo 《Journal of Electronic Materials》2006,35(5):1095-1103
Lead-free solders with excellent material properties and low cost are essential for the electronics industry. It has been
proved that mechanical properties of SnAgCu alloys can be remarkably improved with a minute addition of rare earth (RE) elements.
For comparison and optimization, three valuable solder candidates, Sn3.8Ag0.7Cu0.05RE, Sn3Ag0.5Cu0.05RE, and Sn2.9Ag1.2Cu0.05RE,
were chosen due to the excellent properties of their own SnAgCu basic alloys. Wetting properties, melting temperature, bulk
tensile properties, and joint tensile and shear properties were investigated. In addition, the microstructures of solder joints
were observed and the effects of microstructure on mechanical properties were analyzed. Experimental results indicated that
the tensile and shear strengths of solder joints were decreased from Sn3.8Ag0.7Cu0.05RE, Sn2.9Ag1.2Cu0.05RE, to Sn3Ag0.5Cu0.05RE,
in order. Such difference in mechanical properties could be attributed to the influence of slightly coarse or strong Cu6Sn5 scallops in the reaction layer as well as superior eutectic network and large volume percentage of large primary intermetallic
compounds (IMCs) inside the solder joints. It is also suggested that the size and volume percentage of large primary IMCs
inside the solder be controlled. In addition, serration morphology was observed at the edge of large primary and eutectic
IMCs in the three solder joints, which could be related to the content of Ag, Cu, and RE. The serration morphology was proved
to be beneficial to mechanical properties theoretically. Furthermore, the three alloys investigated possessed similar wetting
properties, melting temperatures, and bulk tensile properties. 相似文献
15.
This work investigates the effect of reflow and the thermal aging process on the microstructural evolution and microhardness
of five types of Sn-Ag based lead-free solder alloys: Sn-3.7Ag, Sn-3.7Ag-1Bi, Sn-3.7Ag-2Bi, Sn-3.7Ag-3Bi, and Sn-3.7Ag-4Bi.
The microhardness and microstructure of the solders for different cooling rates after reflow at 250°C and different thermal
aging durations at 150°C for air-cooled samples have been studied. The effect of Bi is discussed based on the experimental
results. It was found that the microhardness increases with increasing Bi addition to Sn-3.7Ag solder regardless of reflow
or thermal aging process. Scanning electron microscopy images show the formation of Ag3Sn particles, Sn-rich phases, and precipitation of Bi-rich phases in different solders. The increase of microhardness with
Bi addition is due to the solution strengthening and precipitation strengthening provided by Bi in the solder. The trend of
decrease in microhardness with increasing duration of thermal aging was observed. 相似文献
16.
The present study investigated interfacial reactions between Cu substrates and Bi-Ag alloys during soldering. Without forming
intermetallic compounds (IMCs), the molten solder grooved and further penetrated along the grain boundaries (GBs) of the Cu
substrate. An increase in Ag content enhanced GB grooving, raised the dissolution rate and also the amount of dissolved Cu
in molten Bi. A stoichiometric Cu-Bi phase formed isothermally in liquid solders and considerably affected the Cu dissolution
kinetics. The results also show that Bi-Ag/Cu joints possessed a better shear strength than the Pb-Sn/Cu, which implies that
mechanical bonding by grain-boundary grooves was strong enough to withstand shear deformation. 相似文献
17.
18.
In this work, we have systematically investigated the evolution of microstructure and of intermetallic compounds (IMCs), in
particular, for lead-free SnAgCuEr solders during isothermal aging tests. The effect of trace amounts of the rare earth element
Er on this process has also been studied. The results indicate that diffusion and reassembly occur in the solder matrix during
the aging process, and the major influence of the rare earth element Er is concentrated on the nucleation sites. ErSn3 IMCs formed from the molten solder provide heterogeneous nucleation sites for the IMCs in the soldering and aging process.
Subsequently, the Cu-Sn IMCs produced during soldering and Ag-Sn IMCs precipitated during the aging process have uniform size
and evenly distribute in the solder matrix, and the refinement effect has been achieved in Er-containing solder joints. In
addition, some cracks can be seen in Er-free solder joints, and the cracks may nucleate and propagate in the structure along
the compound/solder boundaries after long aging times. 相似文献
19.