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1.
The Sn-3.5Ag and Sn-3.5Ag-0.2Co-0.1Ni lead-free solders were investigated on common electronics substrates, namely, organic
solderability preservative (OSP) and electroless Ni/immersion Au (ENIG) surface finishes. The formation of Kirkendall voids
at the interfacial region during isothermal solid aging was explored. For the Sn-3.5Ag-0.2Co-0.1Ni/OSP solder joint, the Kirkendall
voids were present after isothermal solid-state aging at higher temperature (e.g., 150°C); however, the size of voids did
not change remarkably with prolonged aging time due to the depressed Cu3Sn layer growth. For ENIG surface finishes, the 0.2Co-0.1Ni additions seemed to enhance the longitudinal groove-shaped voids
at the Ni3P layer; however, void formation at the solder/Ni3Sn4 interface was effectively reduced. This might be attributed to the reduced Sn activity in the solder matrix and the suppressed
Ni-P-Sn layer formation. 相似文献
2.
F. Guo J. Lee J. P. Lucas K. N. Subramanian T. R. Bieler 《Journal of Electronic Materials》2001,30(9):1222-1227
The creep deformation behavior of eutectic Sn-3.5Ag based Ni particle rein forced composite solder joints was investigated.
The Ni particle reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic
Sn-3.5Ag solder paste. Static-loading creep tests were carried out on solder joint specimens at 25 C, 65 C, and 105 C, representing
homologous temperatures ranging from 0.6 to 0.78. A novel-design, miniature creep-testing frame was utilized in this study.
Various creep parameters such as the global and localized creep strain, steady-state creep rate, onset of tertiary creep and
the activation energy for creep were quantified by mapping the distorted laser ablation pattern imprinted on the solder joint
prior to testing. The Ni-reinforced composite solder joint showed improved creep resistance compared to the results previously
reported for eutectic Sn-3.5Ag solder, Sn-4.0Ag-0.5Cu solder alloys, and for eutectic Sn-3.5Ag solder reinforced with Cu or
Ag particle reinforcements. The activation energy for creep was ∼0.52 eV for Sn-3.5Ag and Sn-4Ag-0.5Cu solder alloys. The
activation energies ranged from 0.55–0.64 eV for Cu, Ag, and Ni reinforced composite solder joints, respectively. Most often,
creep fracture occurred closer to one side of the solder joint within the solder matrix. 相似文献
3.
Rajen S. Sidhu Shantanu V. Madge Xin Deng Nikhilesh Chawla 《Journal of Electronic Materials》2007,36(12):1615-1620
We report on the nature of the orientation of Ag3Sn and the Ag3Sn/Sn interface in Sn-3.5Ag solder. Orientation imaging microscopy (OIM) and transmission electron microscopy (TEM) were used
to characterize the orientation and nature of the interface, respectively. OIM and TEM showed that Sn-3.5Ag containing spherical
Ag3Sn particles does not have a preferred orientation with respect to the Sn matrix. However, needle-like Ag3Sn formed during slower cooling appeared to have a preferred orientation within individual Sn colonies. The interface between
Sn and Ag3Sn appeared to be incoherent, as confirmed by high-resolution TEM analysis. 相似文献
4.
Effects of Co addition in eutectic Sn-3.5Ag solder on shear strength and microstructural development
In this study, the approach of composite solder using eutectic Sn-3.5Ag solder and Co was tried. Co particles and Sn-3.5Ag solder paste were mechanically mixed at Co weight fractions from 0.1% to 2.0%. For the Co-mixed Sn-3.5Ag solder pastes, their melting temperatures and spreading areas were measured. The solder pastes were stencil printed on test substrates and reflowed to form solder bumps. Ball shear test was performed to examine shear strength of Co-reinforced Sn-3.5Ag solder bumps. As a result, Co addition up to 2 wt.% did not alter the melting temperature under heating but reduced undercooling. The maximum shear strength of Co-reinforced Sn-3.5Ag solder bumps increased by 28% compared to normal ones. The increase in shear strength can be attributed to the (Cu,Co)3Sn2 intermetallic compounds. 相似文献
5.
The effect of microstructure obtained by rapid or slow solidification and cooling of a Sn-3.5%Ag lead-free solder alloy on
the creep strength has been investigated. The rapidly cooled alloy showed that the microstructure consisted of the primarily
crystallized Sn phase and the quasi-eutectic phase, where fine Ag3Sn particles dispersed in the Sn matrix. In the slowly cooled alloy, large platelets of Ag3Sn were formed sparsely in the Sn matrix. A difference of about 2.5 orders of magnitude in the cooling rate translates to
about 1.5 orders of magnitude in the creep-rupture time. Accordingly, fine particle dispersion of Ag3Sn is considered to be very beneficial for the restraining of creep deformation, that is, for the decreasing of creep rate
of the Sn-3.5%Ag alloy, compared with the effect of large platelets of Ag3Sn sparsely formed in the Sn matrix. 相似文献
6.
在焊点与铜基之间形成的Cu-Sn合金成分对表面安装器件的疲劳寿命起着关键性的作用。本文着重研究了93.5Sn3.5Ag(简写为Sn-Ag)焊料与Cu基界面间形成的合金层,通过电子扫描显微镜(SEM),X衍射(XDA)及能谱X射线(EDX)等分析发现,在Sn-Ag与Cu基界面上存在Cu6Sn5及Cu3Sn两种合金成分,且随着热处理时间增加,Cu6Sn5合金层增厚,并在该处容易出现裂纹而导致焊点强度减弱,从而使焊点产生疲劳失效。 相似文献
7.
The formation of Ag3Sn plates in the Sn-Ag-Cu lead-free solder joints for two different Ag content solder balls was investigated in wafer level
chip scale packages (WLCSPs). After an appropriate surface mount technology reflow process on a printed circuit board, samples
were subjected to 150°C high-temperature storage (HTS), 1,000 h aging, or 1,000 cycles thermal cycling test (TCT). Sequentially,
the cross-sectional analysis was scrutinized using a scanning electron microscope/energy dispersive spectrometer (SEM/EDX)
to observe the metallurgical evolution of the amount of the Ag3Sn plates at the interface and the solder bulk itself. Pull and shear tests were also performed on samples. It was found that
the interfacial intermetallic compound (IMC) thickness, the overall IMC area, and the numbers of Ag3Sn plates increase with increasing HTS and TCT cycles. The amount of large Ag3Sn plates found in the Sn-4.0Ag-0.5 Cu solder balls is much greater than that found in the Sn-2.6Ag-0.5Cu solder balls; however,
no significant difference was found in the joint strength between two different Ag content solder joints. 相似文献
8.
采用Sn0.45A g0.68Cu亚共晶无铅钎料通过热浸焊获得铜接头,在-45~125℃的温度循环区间内对焊接接头进行200、400、600、800、1000周期高低温热冲击循环实验,分析了焊点的剪切强度变化,组织演变及界面IM C的生长规律。结果表明:焊点组织中弥散分布的Cu6Sn5相内部晶粒逐渐粗化长大,最后转变为圆形或者椭圆形;焊点界面IM C层厚度明显增厚,且由最初的细小扇贝状转变为大的波浪状,最终趋于平缓;焊点的剪切强度随热冲击循环周期的增加而急剧下降,经400周期的热冲击循环之后,焊点的剪切强度已下降了约22.5%,在400周期的热冲击循环后开始变得平缓,最后趋于稳定。 相似文献
9.
The evolution of intermetallic compounds (IMCs) generated between Sn-3.5Ag solder doped by additive couples (namely, 0.2mass%Co
and 0.1mass%Ni) and Cu substrate was characterized. After soldering, the additive couples, Co-Ni, were all detected at the
intermetallic region. The microstructure of intermetallic was identified as (Cu, Ni, Co)6Sn5 by electron probe microanalysis (EPMA) and x-ray diffraction (XRD). However, the morphology of (Cu, Ni, Co)6Sn5 was converted to columnar like and was not as dense as the typical scallop-like Cu6Sn5. A duplex structure of (Cu, Ni, Co)6Sn5, namely, two distinct regions bearing different concentrations of Ni and Co, was observed. Much higher Ni and Co concentrations
were probed in the outer intermetallic region adjacent to the solder matrix, while lower concentration at the inner region
was verified. After aging, the intermetallic (Cu, Ni, Co)6Sn5 tended to be dense, while the growth rate was depressed at the early stage. In addition, the Cu3Sn phase was not detected after aging at 110°C, while it appeared at 130°C and 150°C for 504 h. Using the nanoindentation
technique, some mechanical properties of (Cu, Ni, Co)6Sn5 were investigated. The lower hardness and Young’s modulus of the outer intermetallic region was revealed. After aging treatment,
both the hardness and Young’s modulus values were elevated. 相似文献
10.
For development of a lead-free composite solder for advance electrical components, lead-free Sn3.5Ag0.5Cu solder was produced by mechanically mixing 0.5 wt.% TiO2 nanopowder with Sn3.5Ag0.5Cu solder. The morphology and growth kinetics of the intermetallic compounds that formed during the soldering reactions between Sn3.5Ag0.5Cu solder with intermixed TiO2 nanopowder and Cu substrates at various temperatures ranging from 250 to 325 °C were investigated. A scanning electron microscope (SEM) was used to quantify the interfacial microstructure at each processing condition. The thickness of interfacial intermetallic layers was quantitatively evaluated from SEM micrographs using imaging software. Experimental results show that a discontinuous layer of scallop-shaped Cu-Sn intermetallic compounds formed during the soldering. Kinetics analysis shows that the growth of such interfacial Cu-Sn intermetallic compounds is diffusion controlled with an activation energy of 67.72 kJ/mol. 相似文献
11.
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
12.
The tensile behavior and microstructure of bulk, Sn-3.5Ag solders as a function of cooling rate were studied. Cooling rate
is an important processing parameter that affects the microstructure of the solder and, therefore, significantly influences
mechanical behavior. Controlled cooling rates were obtained by cooling specimens in different media: water, air, and furnace.
Cooling rate significantly affected secondary dendrite-arm size and spacing of the Sn-rich phase, as well as the aspect ratio
of Ag3Sn. The Sn-rich dendrite-arm size and spacing were smaller for water-cooled specimens than for air-cooled specimens. Furnace
cooling yielded a nearly eutectic microstructure because the cooling rate approached equilibrium cooling. The morphology of
Ag3Sn also changed from spherical, at a fast cooling rate, to a needlelike morphology for slower cooling. The changes in the
microstructure induced by the cooling rate significantly affected the mechanical behavior of the solder. Yield strength was
found to increase with increasing cooling rate, although ultimate tensile strength and strain-to-failure seemed unaffected
by cooling rate. Cooling rate did not seem to affect Young’s modulus, although a clear coorelation between modulus and porosity
was obtained. The mechanical behavior was correlated with the observed microstructure, and fractographic analysis was employed
to elucidate the underlying damage mechanisms. 相似文献
13.
In-situ tensile tests of as-cast 96.5Sn3.5Ag eutectic solder were performed under the scanning electron microscope (SEM) using
different strain rates at room temperature, and various crack initiation and propagation behavior was observed on the specimen
surface. It was found that, due to the existence of Ag3Sn intermetallic particles and the special microstructure of β-Sn phases in Sn3.5Ag solder, grain boundary sliding (GBS) was
no longer the dominant mechanism for this Pb-free solder. In the lower strain rate regime, accompanied by partial intragranular
cracks, intergranular fracture along the grain boundaries in Sn-Ag eutectic structure or along the interphase boundaries between
Sn-rich dendrites and Sn-Ag eutectic phases occurred primarily for the Sn3.5Ag solder in the early tensile stage. However,
significant plastic deformation was observed in large areas for the specimens tested at higher strain rates, and cracks propagated
in a transgranular manner across the Sn dendrites and Sn-Ag eutectic structure. 相似文献
14.
J. G. Maveety P. Liu J. Vijayen F. Hua E. A. Sanchez 《Journal of Electronic Materials》2004,33(11):1355-1362
The microstructure and shear strength characteristics of pure Sn and the eutectic compositions of Sn-37Pb, Sn-0.7Cu, and Sn-3.5Ag
prepared under identical reflow conditions but subjected to two different cooling conditions were evaluated at room temperature.
For the four solders, the ultimate shear strength increased with increasing strain rate from 10−5 s−1 to 10−1 s−1. Decreasing the cooling rate tended to decrease the ultimate shear strength for both the Sn-0.7Cu and Sn-3.5Ag solders. The
effects of work hardening resulting from increased strain rate were more prevalent in quench-cooled (QC) samples. 相似文献
15.
Yun-Hwan Jo Joo Won Lee Sun-Kyoung Seo Hyuck Mo Lee Hun Han Dong Chun Lee 《Journal of Electronic Materials》2008,37(1):110-117
A combination solder of Sn-3.0Ag-0.5Cu (numbers are all in weight percent unless specified otherwise) wrapped by Sn-57Bi-1Ag
was tested for application to three-dimensional (3-D) multistack packaging. The experimental variables controlled were the
reflow peak temperatures (170, 185, 200, and 230°C), the reflow cycles (up to four times), and the mask which controls the
amount of Sn-57Bi-1Ag solder paste (two sizes). We demonstrate and evaluate the combination solder structure, focusing on
microstructural changes and the shear strength. The degree of mixing in the combination solder, which is enhanced by an increase
in the reflow peak temperature, is independent of the number of reflow cycles. The ball shear strength and the lab shear strength
both increased with increases in the reflow peak temperatures. This behavior is explained by the amount of the brittle Bi
phase that constitutes the eutectic Sn-Bi phase. 相似文献
16.
The effect of cooling rate on microstructure and creep behavior of bulk, eutectic Sn-3.5Ag solders was studied. The cooling
rate is an important processing variable that significantly affects the microstructure of the solder and therefore determines
its mechanical behavior. Controlled cooling rates were obtained by cooling specimens in different media: water, air, and furnace,
which resulted in cooling rates of 24°C/s, 0.5°C/s, and 0.08°C/s, respectively. The cooling rate decreased the secondary dendrite
arm size and the spacing of the Sn-rich phase, as well as the morphology of Ag3Sn. The Sn-dendrite arm size and spacing were smaller at fast cooling rates, while slower cooling rates yielded a nearly eutectic
microstructure. The morphology of Ag3Sn also changed from relatively spherical, at faster cooling rates, to needlelike for slower cooling. The effect of cooling
rate on creep behavior was studied at 25°C, 60°C, 95°C, and 120°C. Faster cooling rates were found to increase the creep strength
of the solder due to the refinement of the solder microstructure. Stress exponents, n, indicated that dislocation climb was
the controlling mechanism. Activation energies, for all cooling rates, indicated that the dominant diffusional mechanism corresponded
to dislocation pipe diffusion of Sn. Grain boundary sliding (GBS) measurements were conducted, using both scanning electron
microscopy (SEM) and atomic force microscopy (AFM). It was observed that GBS had a very small contribution to the total creep
strain. 相似文献
17.
本文研究了热处理时间对不同组分的42Sn58Bi-96.5Sn3.5Ag焊料疲劳性能的影响,研究发现适当的热处理时间能提高焊点的机械强度,延长焊点的疲劳寿命。 相似文献
18.
During the reflow process of Sn-3.5Ag solder ball grid array (BGA) packages with Ag/Cu and Au/Ni/Cu pads, Ag and Au thin films
dissolve rapidly into the liquid solder, and the Cu and Ni layers react with the Sn-3.5Ag solder to form Cu6Sn5 and Ni3Sn4 intermetallic compounds at the solder/pad interfaces, respectively. The Cu6Sn5 intermetallic compounds also appear as clusters in the solder matrix of Ag surface-finished packages accompanied by Ag3Sn dispersions. In the solder matrix of Au/Ni surface-finished specimens, Ag3Sn and AuSn4 intermetallics can be observed, and their coarsening coincides progressively with the aging process. The interfacial Cu6Sn5 and Ni3Sn4 intermetallic layers grow by a diffusion-controlled mechanism after aging at 100 and 150°C. Ball shear strengths of the reflowed
Sn-3.5Ag packages with both surface finishes are similar, displaying the same degradation tendencies as a result of the aging
effect. 相似文献
19.
Low-cycle fatigue (LCF) data of Sn-Ag eutectic solder (96.5Sn-3.5Ag) under various temperatures and frequencies has been described
using three different prediction models, i.e., Coffin-Manson model, Smith-Watson-Topper (SWT) model, and Morrow energy model.
The LCF behavior represented by the present prediction models showed temperature and frequency dependences, i.e., the fatigue
ductility coefficient increased with increasing frequency and decreasing temperature. In order to better correlate the LCF
data, a flow stress and/or frequency-dependent modifications were introduced to the Coffin-Manson and Morrow energy models.
The frequency-modified Coffin-Manson model could not describe the influence of temperature on LCF behavior, while the flow
stress-modified frequency-modified Morrow energy model, into which the metallurgical response (flow stress and frequency)
was introduced to account for the effect of temperature and frequency on LCF behavior, gave reasonable predictions of LCF
data under various temperatures and frequencies. 相似文献
20.
In this study, we investigated the effect of the current density on the interfacial reaction and mechanical reliability of an electroless Ni/immersion Au (ENIG) substrate with Sn-3.5Ag solder. We first evaluated the interfacial reactions of the solder joint under aging for up to 800 h and current stressing with current densities of 3 × 102 A/cm2 and 5 × 103 A/cm2. Also, we successfully revealed the correlation between the interfacial reaction behavior and mechanical reliability under current stressing. With increasing aging time, the thickness of the Ni3Sn4 layer increased. At both low and high current densities, the thickness of the Ni3Sn4 layer increased up to 400 h and decreased thereafter at the cathode, while that of the IMC increased up to 800 h at the anode. After the die shear test, the ductile fracture was observed in the as-reflowed joint without current stressing. The fracture mode changed from ductile fracture to brittle fracture when thermal aging and current flow were simultaneously applied. The combination of the current stressing and isothermal aging at high temperature significantly deteriorated the mechanical reliability of the solder joint. 相似文献