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The electroless nickel immersion gold (ENIG) surface finish is widely used in electronic packaging. The ENIG induced Au embrittlement has been investigated in SnPb/ENIG/Cu solder joint since several years ago. However, in Sn-based lead-free solder joint, discrepancies still exist about the influence of Au finish on the reliability of the solder joint. This study investigated the effects of ENIG surface finish on the interfacial reaction and thus the mechanical property of Sn-based solder joints. Experimentally, two types of ENIG with different thickness of Au layer were fabricated. The results indicated that the Au layer dissolved into the solder matrix readily in the soldering stage, and then affected the shear strength of the solder joint significantly. The Au migration occurred in the solder joint during isothermal aging. The Au migration is more apparent when the Cu6Sn5 type compound formed at the interface. The embrittlement caused by the weak interface between the (Au1−xNix)Sn4 and Ni3Sn4 layers cannot be observed in this study. 相似文献
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M. L. Huang T. Loeher D. Manessis L. Boettcher A. Ostmann H. Reichl 《Journal of Electronic Materials》2006,35(1):181-188
A comparative study of solid/solid interfacial reactions of electroless Ni-P (15 at.% P) with lead-free solders, Sn-0.7Cu,
Sn-3.5Ag, Sn-3.8Ag-0.7Cu, and pure Sn, was carried out by performing thermal aging at 150°C up to 1000 h. For pure Sn and
Sn-3.5Ag solder, three distinctive layers, Ni3Sn4, SnNiP, and Ni3P, were observed in between the solder and electroless Ni-P; while for Sn-0.7Cu and Sn-3.8Ag-0.7Cu solders, two distinctive
layers, (CuNi)6Sn5 and Ni3P, were observed. The differences in morphology and growth kinetics of the intermetallic compounds (IMCs) at the interfaces
between electroless Ni-P and lead-free solders were investigated, as well as the growth kinetics of the P-enriched layers
underneath the interfacial IMC layers. With increasing aging time, the coarsening of interfacial Ni3Sn4 IMC grains for pure Sn and Sn-3.5Ag solder was significantly greater than that of the interfacial (CuNi)6Sn5 IMC grains for Sn-0.7Cu and Sn-3.8Ag-0.7Cu solders. Furthermore, the Ni content in interfacial (CuNi)6Sn5 phase slightly increased during aging. A small addition of Cu (0.7 wt.%) resulted in differences in the type, morphology,
and growth kinetics of interfacial IMCs. By comparing the metallurgical aspects and growth kinetics of the interfacial IMCs
and the underneath P-enriched layers, the role of initial Cu and Ag in lead-free solders is better understood. 相似文献
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K. -W. Moon C. E. Johnson M. E. Williams O. Kongstein G. R. Stafford C. A. Handwerker W. J. Boettinger 《Journal of Electronic Materials》2005,34(9):L31-L33
Localized cracking of surface oxide has been proposed as a necessary step in the nucleation of Sn whiskers in Sn electrodeposited
films. To evaluate the effects of the oxide film on Sn whisker growth, a bright Sn-Cu electrodeposited film was inserted into
an ultrahigh vacuum Auger system, cleaned using an Ar− ion beam to remove the oxide film, and aged in the 2×10−9 Pa Auger system chamber. Whiskers and other features present during Ar+ ion cleaning left visible “shadows” on the surface. During aging in the ultrahigh vacuum system, new whiskers, identified
by the absence of the telltale shadows, nucleated and grew. Based on these observations, the presence or absence of an oxide
film has a minimal effect on Sn whisker nucleation and growth. 相似文献
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Sun-Kyoung Seo Moon Gi Cho Hyuck Mo Lee Won Kyoung Choi 《Journal of Electronic Materials》2006,35(11):1975-1981
We chose Sn−2.8Ag−20In and Sn−10Bi−10In (numbers are in weight percentages unless specified otherwise) as Pb-free solder materials
for intermediate-step soldering. We then investigated how the two solders reacted with the under bump metallurgy (UBM) of
Au/Ni (Au: 1.5 μm and Ni: 3 μm) at 210°C, 220°C, 230°C, and 240°C for up to 4 min. All, of the Au UBM was dissolved into the
solder matrix as soon as the interfacial reaction started. The reaction formed Au(In, Sn)2 in the case of SnAgIn, and it formed Au(Sn, In)4 and Au(In, Sn)2 in the case of SnBiIn. The formation mechanism of the intermetallic phases is explained thermodynamically. The exposed Ni
layer reacted with the solder and formed Ni28Sn55In17 in case of SnAgIn, and formed Ni3(Sn, In)4 in case of SnBiIn, at the solder joint interface. Under the same soldering conditions, the Ni3(Sn,In)4 layer in the SnBiIn/UBM is thicker than the Ni28Sn55In17 layer in the SnAgIn/UBM. Because of the thicker intermetallic compound layer, the SnBiIn solder joint has weaker shear strength
than the SnAgIn solder joint. 相似文献
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Zhiheng Huang Conway P.P. Changqing Liu Thomson R.C. 《Components and Packaging Technologies, IEEE Transactions on》2006,29(1):98-104
Market demands and legislation are driving the electronics-manufacturing sector to move rapidly toward a lead-free future, with Pb-containing electronics products to be banned in Europe after 2006. Although the related scientific research has been undertaken for a decade, a number of technical complications still exist, which are further exacerbated due to the concurrent developments in miniaturization and multifunctionality of microelectronic products. As the packaging joint geometry shrinks toward a microscopic scale, the joint fabrication and reliability become extremely sensitive to the composition and resulting microstructure generated from the chosen joining process and materials. The current level of understanding of such issues is still in its infancy and therefore requires further fundamental study. Thermodynamic modeling is employed in this work as a computational tool to study the sensitivity of processing ranges (e.g., reflow temperature) and the resultant reliability of the microjoints by changing the alloying elements and their content in Sn-based lead-free systems. The work is implemented using the MTDATA program developed by the National Physical Laboratory. With a newly developed database containing critically assessed thermodynamic data appropriate for lead-free solder systems, MTDATA allows the prediction of the liquid-solid transformation and phase formation, for example, as a function of chemical composition and temperature. The paper emphasizes the formation and mass fraction of intermetallic precipitates of different phases in the bulk solder joints and the modeling is also validated through experimental work and recent literature. The results are expected to assist the optimization of processing parameters and cost-effective production using lead-free solders. 相似文献
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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
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Using nanoindentation and energy dispersive X-ray spectrometry (EDS), we have conducted an investigation into corner failures to elucidate not only the nanomechanical properties of Sn37Pb solder balls but also the effects of temperature cycling tests (TCTs). We found that the hardness of Sn37Pb solder balls was greater in central locations [1.18 ± 0.05 GPa for room-temperature (RT) sample; 1.3 ± 0.05 GPa for TCT sample], but had standard values in corner locations (> 0.2 ± 0.02 GPa). The modulus increased after the TCTs. Nevertheless, the mechanical properties were closely related to the average area of the α-Pb phase. The average area of the Pb-rich region was more stable after the TCTs than that of the RT sample, due to the enhanced mechanical properties of the Sn37Pb solder, suggesting good reliability. From an analysis of average areas in the RT sample, it appears that the Pb-rich solid solution that formed led to weak SnPb bonds near the corner locations. Electron back-scattered diffraction measurements revealed that grains with grain boundaries formed as a result of accelerated TCT cycling. We conclude that SnPb recrystallization was initiated and propagated after the TCTs, followed by propagation to the interfacial region. 相似文献
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A. Micol A. Zeanh T. Lhommeau S. Azzopardi E. Woirgard O. Dalverny M. Karama 《Microelectronics Reliability》2009,49(9-11):1370-1374
This work examines the thermal fatigue effects on different configurations of power modules used in harsh aeronautical environment. They are used in various applications where the temperature cycling due to the working environment is the most limiting fact. In this case, it is highlighted that the topology assembly choice is a critical point to reach the lifetime required for the final application. In addition, it is proposed to correlate the probabilistic finite elements calculus to the experimental accelerated ageing tests on test vehicle, in order to determine the best configuration of assembling stack consisting of baseplate/RoHS solder/metallized substrate. 相似文献
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W. -M. Chen P. Mccloskey P. Byrne P. Cheasty G. Duffy J. F. Rohan J. Boardman A. Mulcahy S. C. O’Mathuna 《Journal of Electronic Materials》2004,33(8):900-907
The interfacial reaction between electroless Ni(P) under-bump metallization (UBM) and solders is studied. A P-rich layer forms
in the UBM along the solder side after reflow and thermal aging. Crack formation inside the P-rich layer can sometimes penetrate
throughout the entire UBM layer structure. The Ni(P) UBM degradation occurs earlier in the Sn3.5Ag solder than in Sn37Pb because
of its higher reflow temperature. Despite the formation of a P-rich layer and cracks inside the UBM, it still keeps its original
function within the high-temperature storage period in this study. Explanations for the formation of the P-rich layer and
cracks in the UBM are outlined along with explanations for the Ni(P) UBM degradation process. 相似文献
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Isothermal aging effects on the microstructure and solder bump shear strength of eutectic Sn37Pb and Sn3.5Ag solders 总被引:1,自引:0,他引:1
The reliability of the eutectic Sn37Pb (63%Sn37%Pb) and Sn3.5Ag (96.5%Sn3.5%Ag) solder bumps with an under bump metallization (UBM) consisting of an electroless Ni(P) plus a thin layer of Au was evaluated following isothermal aging at 150 °C. All the solder bumps remained intact after 1500 h aging at 150 °C. Solder bump microstructure evolution and interface structure change during isothermal aging were observed and correlated with the solder bump shear strength and failure modes. Cohesive solder failure was the only failure mode for the eutectic Sn37Pb solder bump, while partial cohesive solder failure and partial Ni(P) UBM/Al metallization interfacial delamination was the main failure mode for eutectic Sn3.5Ag solder bump. 相似文献
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M. T. Sheen Y. H. Ho C. L. Wang K. C. Hsieh W. H. Cheng 《Journal of Electronic Materials》2005,34(10):1318-1323
The joint strength and microstructure of fluxless Au/Sn solders in InP-based laser-diode packages after thermal-aging testing
were studied experimentally and numerically. Specimens were aged at 150°C for up to 64 days. The joint strength decreased
as aging time increased. The microstructure and fracture surface of the Au/Sn solder joints showed that the joint strength
decrease was caused by both the enlargement of the initial voids and an increase in the number of voids as the aging time
increased. Finite-element method (FEM) simulations of joint strength were in good agreement with experimental measurements.
Both experimental and numerical results indicate that the enlargement of the initial voids and an increase in the number of
voids, caused by stress concentration as the aging period increased, resulted in the weakness of joint strength. The effect
of temperature-cycling testing on the power variation of the InP laser diodes using fluxless Au/Sn solders was also studied.
It was shown that the laser diodes operated in the stable condition up to 500 cycles. 相似文献
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M. T. Sheen C. M. Chang H. C. Teng J. H. Kuang K. C. Hsieh W. H. Cheng 《Journal of Electronic Materials》2002,31(8):895-902
The joint strength and fracture surface of Pb/Sn and Au/Sn solders in laserdiode packages after thermal-aging testing were
studied experimentally. Specimens were aged at 150°C for up to 49 days. The joint strength decreased as aging time increased.
The microstructure and fracture surface of the Pb/Sn and Au/Sn solder joints showed that the joint strength decrease was caused
by both the enlargement of the initial voids and an increase in the number of voids as aging time increased. The formation
of Kirkendall voids with intermetallic-compound (IMC) growth of the Pn/Sn solder as aging time increased was also a possible
mechanism for the joint-strength reduction. Finite-element method (FEM) simulations were performed on the joint-strength estimation
of Pb/Sn and Au/Sn solders in thermal-aging tests. The coupled thermal-elasticity-plasticity model was used to simulate distributions
of the thermal and residual stresses, creep deformation, and joint-strength variations in the solder joints under various
thermal-aging tests. Simulation results were in good agreement with the experimental measurements that the solder-joint strength
decreased as aging time increased. The result suggests that the FEM is an effective method for analyzing and predicting the
solder-joint strength in laserdiode packages. 相似文献
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L. N. Ramanathan J. W. Jang J. K. Lin D. R. Frear 《Journal of Electronic Materials》2005,34(10):L43-L46
The solid-state annealing behavior of two high-lead solders, 95Pb5Sn and 90Pb10Sn (in wt.%), was examined. After reflow, Cu3Sn intermetallics formed on the Cu under bump metallurgy (UBM) for both solder alloys. However, solidstate annealing produced
significantly different reaction morphologies for the two solder compositions. The Cu3Sn intermetallics spalled off faster at higher temperatures in the 95Pb5Sn solder. In the case of 90Pb10Sn solder, the Cu3Sn intermetallics continued to grow even after 1500 h at 170°C. The difference was explained by a two-step phenomenon—Sn diffusion
from the bulk solder region to the solder/Cu3Sn interface (JSn), and subsequent intermetallic formation (ICu3Sn) by interdiffusion of Cu and Sn. For 95Pb5Sn, the relation, JSn < ICu3Sn was postulated because of insufficient supply of Sn. The relation, JSn > ICu3Sn was suggested for the continuous intermetallic growth of the 90Pb10Sn solder. Although a small difference was expected between
the two quantities in both solder alloys, the difference in the solid-state annealing behavior was dramatic. 相似文献
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The mechanical alloying (MA) process was employed as an alternative method to produce the lead-free solder pastes of Sn-3.5Ag-xNi
(x=0.1, 0.5, 1.0, 1.5, and 2.0) in this study. When the Ni concentration was low (x=0.1, 0.5), MA particles agglomerated to
a flat ingot with particle sizes >100 μm. For higher Ni concentration (x=1.0, 1.5, and 2.0), MA particles turned into fragments
with particle sizes <100 μm. The particle size of the solders appeared to be dependent on the Ni concentration. To reduce
the particle size of SnAgNi alloys with low Ni concentration, Ni3Sn4 nanoparticles were doped into Sn and Ag powders to derive a Ni3Sn4-doped solder. For the Ni3Sn4-doped solder, the particle size was smaller than that doped by the pure Ni. The distinction of milling mechanism between
Ni3Sn4-doped solder and the pure Ni-doped solder by MA process was probed and discussed. In addition, differential scanning calorimetry
(DSC) results ensured its feasibility in applying the solder material in the reflow process. Wettability tests between solders
and Cu substrate also revealed that the wetting angles for Ni3Sn4-doped solder with low Ni concentration (0.1 and 0.5 wt.%) were smaller than those for pure Ni-doped solder. The wetting angles
on both Cu substrate and electroplated Ni metallization for SnAgNi solders were also comparable with commercial Sn-3.5Ag and
Sn-3.0Ag-0.5Cu solders. Favorable wettability of the as-derived solder in this study was clearly demonstrated. 相似文献
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J. Shen Y. C. Liu H. X. Gao C. Wei Y. Q. Yang 《Journal of Electronic Materials》2005,34(12):1591-1597
A series of Sn-Ag solders were prepared by arc melting and their phase evolution was investigated as a function of cooling
rates. It was found that bulk Ag3Sn intermetallic compounds (IMCs) separated out only in the slowly cooled Sn-4.0Ag solder. This would be explained by the
strong kinetic undercooling, arising from the rapid cooling conditions, which leads to the actual eutectic point shifts in
the direction of higher Ag concentration. Thus, the eutectic and hypereutectic alloys experience a metastable hypoeutectic
solidification route instead. All formed fractions of bulk Ag3Sn IMCs in solders, measured by quantitative microstructural analysis and thermal analysis, are larger than those predicted
by the equilibrium phase diagram. The reasoning for this could be attributed to fine Ag3Sn phases, which cling to the primary Ag3Sn crystal during the eutectic reaction for their matching crystalline orientation relationship. Furthermore, the fraction
of bulk Ag3Sn IMCs increases gradually with increasing the cooling rate in the slowly cooled Sn-4.0Ag alloy, which fits with the prediction
of eutectic solidification theory: the increase of cooling rate would decrease the surface energy of fine Ag3Sn particles and primary Ag3Sn crystal, and make fine Ag3Sn particles cling to primary Ag3Sn crystal easily to form bulk Ag3Sn IMCs. 相似文献
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电子封装与组装焊点界面反应及微观组织研究进展 总被引:1,自引:0,他引:1
软钎焊焊点界面反应是连接金属的最古老的冶金工艺过程。随着倒装芯片(FC)、球栅阵列(BGA)和芯片级封装(CSP)等面封装技术的兴起,近年来Sn基钎料被广泛应用于微电子制造,包括芯片和基板之间的封装互连以及基板与印制电路板之间的组装互连。这就需要系统地研究Sn基钎料焊点界面反应及微观组织。从形态学、热力学和动力学的角度回顾总结了SnPb共晶钎料、高Pb钎料和无Pb钎料与Cu、Ni、Au/Ni/Cu、PdAg焊盘之间的界面反应。 相似文献