共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
Because of excellent wetting and mechanical properties, SnAgCu solder alloys have been regarded as the most promising Pb-free
substitutes for the SnPb solder. The Sn-3.8Ag-0.7Cu solder has garnered attention because of its creep resistance. However,
under the drives of increasingly finer pitch design and severe service conditions, novel lead-free solders with higher creep
performance may be needed. Adding a surface-active element to an alloy is an effective way to improve the high-temperature
performance of the solder. The present work focuses on the effect of rare earth (RE) on the physical properties, spreading
property, and mechanical properties of SnAgCu solder. Results show that the creep-rupture life of SnAgCu solder joints at
room temperature could be notably increased by adding a minute amount of RE, up to 7 times more than that of SnAgCu solder
joints when containing 1.0wt.%RE. The differential scanning calorimetry (DSC) curves indicated that the melting temperature
of SnAgCu solder with RE increased a little, and no lower melting-temperature, eutectic endothermal peak appears on the DSC
curve. The electrical conductivity of the solder decreased slightly, but it is still superior to the SnPb eutectic solder.
Compared to that of SnPb solder, the coefficient of thermal expansion (CTE) of SnAgCu (RE) is closer to copper, which usually
serves as the substrate of printed circuit boards (PCBs). It is assumed that this will comparably reduce the thermal stress
derived from thermal mismatch between the solder and the PCBs. The RE had no apparent effect on the spreading property, but
when RE added up to 1.0 wt.%, the spreading area of the solder on the copper substrate decreased, obviously, because of mass
oxide. The RE improved the ultimate tensile strength little, but it increased the elongation up to 30%. However, as the content
of the RE increases, the elongation of the solder gradually decreased to the level of SnAgCu when the RE exceeds 0.25 wt.%.
Additionally, RE made the elastic modulus of SnAgCu solder increase, so the resistance to elastic deformation of the solder
is enhanced. The microstructure of SnAgCuRE led to a refining trend as the RE content increased. The RE compounds appeared
in the solder when RE was 0.1 wt.%. This deteriorates the mechanical properties of the solder. The fractography of the tensile
specimen containing 0.1 wt.% indicated a superior ductility to Sn-3.8Ag-0.7Cu bulk solder. However, as RE is increased to
1.0 wt.%, the fractography shows less ductile characteristics, which is believed to serve as the reason that the elongation
of solder degrades as RE increases. Summarily, the most suitable content of RE is within 0.05–0.5 wt.% and is inadvisable
beyond 1.0 wt.%. 相似文献
3.
Microstructure characterization of SnAgCu solder bearing Ce for electronic packaging 总被引:1,自引:0,他引:1
Liang Zhang Song-bai Xue Li-li GaoWei Dai Feng JiYan Chen Sheng-lin Yu 《Microelectronic Engineering》2011,88(9):2848-2851
The creep-rupture lives of Sn3.8Ag0.7Cu and Sn3.8Ag0.7Cu0.03Ce lead-free solder joints for electronic packaging were investigated, respectively. And the relationship between creep behavior and intermetallic compound (IMC: Ag3Sn, Cu6Sn5, CeSn3) particles in SnAgCu/SnAgCuCe solder joints has been obtained. Meanwhile, rare earth Ce concentration gradient and retardation effect of Ce on the IMC layer have been observed at the solder/Cu interface. Moreover, aging reaction of Sn and Cu, and the effect mechanism of rare earth Ce on two IMCs (Cu6Sn5 and Cu3Sn) are reported. 相似文献
4.
Effect of rare earth element addition on the microstructure of Sn-Ag-Cu solder joint 总被引:6,自引:0,他引:6
Bo Li Yaowu Shi Yongping Lei Fu Guo Zhidong Xia Bin Zong 《Journal of Electronic Materials》2005,34(3):217-224
The effects of minimal rare earth (RE) element additions on the microstructure of Sn-Ag-Cu solder joint, especially the intermetallic
compounds (IMCs), were investigated. The range of RE content in Sn-Ag-Cu alloys varied from 0 wt.% to 0.25 wt.%. Experimental
results showed that IMCs could be dramatically repressed with the appropriate addition of RE, resulting in a fine microstructure.
However, there existed an effective range for the RE addition. The best RE content was found to be 0.1 wt.% in the current
study. In addition to the typical morphology of Ag3Sn and Cu6Sn5 IMCs, other types of IMCs that have irregular morphology and uncertain constituents were also observed. The IMCs with large
plate shape mainly contained Ag and Sn, but the content of Ag was much lower than that of Ag3Sn. The cross sections of Cu6Sn5 IMCs whiskers showed various morphologies. Furthermore, some eutectic-like structures, including lamellar-, rod-, and needle-like
phases, were observed. The morphology of eutectic-like structure was related to the RE content in solder alloys. When the
content of RE is 0.1 wt.%, the needle-like phase was dominant, while the lamellar structure prevailed when the RE content
was 0.05 wt.% or 0.25 wt.%. It is suggested that the morphology change of the eutectic-like structure directly affects the
creep properties of the solder joint. 相似文献
5.
Controlling intermetallic compound growth in SnAgCu/Ni-P solder joints by nanosized Cu6Sn5 addition 总被引:1,自引:0,他引:1
Nanosized Cu6Sn5 dispersoids were incorporated into Sn and Ag powders and milled together to form Sn-3Ag-0.5Cu composite solders by a mechanical
alloying process. The aim of this study was to investigate the interfacial reaction between SnAgCu composite solder and electroless
Ni-P/Cu UBM after heating for 15 min. at 240°C. The growth of the IMCs formed at the composite solder/EN interface was retarded
as compared to the commercial Sn3Ag0.5Cu solder joints. With the aid of the elemental distribution by x-ray color mapping
in electron probe microanalysis (EPMA), it was revealed that the SnAgCu composite solder exhibited a refined structure. It
is proposed that the Cu6Sn5 additives were pinned on the grain boundary of Sn after heat treatment, which thus retarded the movement of Cu toward the
solder/EN interface to form interfacial compounds. In addition, wetting is an essential prerequisite for soldering to ensure
good bonding between solder and substrate. It was demonstrated that the contact angles of composite solder paste was <25°,
and good wettability was thus assured. 相似文献
6.
As the electronics industry is moving towards lead-free manufacturing processes, more effort has been put into the reliability study of lead-free solder materials. Various tin–silver–copper-based solders have become widely accepted alternatives for tin–lead solders. In this study, we have tested three different SnAgCu solder compositions. The first consisted of a hypoeutectic 96.5Sn/3.0Ag/0.5Cu solder, the second of a eutectic 95.5Sn/3.8Ag/0.7Cu solder, and the third of a hypereutectic 95.5Sn/4.0Ag/0.5Cu solder. A eutectic SnPb solder was used as a reference. The test boards were temperature-cycled (−40 to +125 °C) until all samples failed. The results of the temperature cycling test were analyzed, and cross-section samples were made of the failed joints. Scanning electron and optical microscopy were employed to analyze the fracture behavior and microstructures of the solder joints. The reliability of lead-free solders and the effect of microstructures on joint reliability are discussed. 相似文献
7.
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
8.
The morphological and compositional evolutions of intermetallic compounds (IMCs) formed at three Pb-free solder/electroless
Ni-P interface were investigated with respect to the solder compositions and reflow times. The three Pb-free solder alloys
were Sn3.5Ag, Sn3.5Ag0.75Cu, and Sn3Ag6Bi2In (in wt.%). After reflow reaction, three distinctive layers, Ni3Sn4 (or Ni-Cu-Sn for Sn3.5Ag0.75Cu solder), NiSnP, and Ni3P, were formed on the electroless Ni-P layer in all the solder alloys. For the Sn3.5Ag0.75Cu solder, with increasing reflow
time, the interfacial intermetallics switched from (Cu,Ni)6Sn5 to (Cu,Ni)6Sn5+(Ni,Cu)3Sn4, and then to (Ni,Cu)3Sn4 IMCs. The degree of IMC spalling for the Sn3.5Ag0.75Cu solder joint was more than that of other solders. In the cases of
the Sn3.5Ag and Sn3Ag6Bi2In solder joints, the growth rate of the Ni3P layer was similar because these two type solder joints had a similar interfacial reaction. On the other hand, for the Sn3.5Ag0.75Cu
solder, the thickness of the Ni3P and Ni-Sn-P layers depended on the degree of IMC spalling. Also, the shear strength showed various characteristics depending
on the solder alloys and reflow times. The fractures mainly occurred at the interfaces of Ni3Sn4/Ni-Sn-P and solder/Ni3Sn4. 相似文献
9.
Bo Wang Jiajun Li Anthony Gallagher James Wrezel Pongpinit Towashirporn Naiqin Zhao 《Microelectronics Reliability》2012,52(7):1475-1482
The poor drop-shock resistance of near-eutectic Sn–Ag–Cu (SAC) solder interconnects drives the research and application low-Ag SAC solder alloys, especially for Sn–1.0Ag–0.5Cu (SAC105). In this work, by dynamic four-point bend testing, we investigate the drop impact reliability of SAC105 alloy ball grid array (BGA) interconnects with two different surface mounting methods: near-eutectic solder paste printing and flux dipping. The results indicate that the flux dipping method improves the interconnects failure strain by 44.7% over paste printing. Further mechanism studies show the fine interfacial intermetallic compounds (IMCs) at the printed circuit board side and a reduced Ag content inside solder bulk are the main beneficial factors overcoming other negative factors. The flux dipping SAC105 BGA solder joints possess fine Cu6Sn5 IMCs at the interface of solder/Cu pads, which increases the bonding strength between the solder/IMCs and the fracture resistance of the IMC grains themselves. Short soldering time of flux dipping joints above the solder alloy liquidus mitigates the growth of interfacial IMCs in size. In addition, a reduced Ag content in flux dipping joint bulk causes a low hardness and high compliance, thus increasing fracture resistance under higher-strain rate conditions. 相似文献
10.
Liang Zhang Cheng-wen He Yong-huan Guo Ji-guang Han Yong-wei Zhang Xu-yan Wang 《Microelectronics Reliability》2012,52(3):559-578
Lead free solder alloys for electronic assembly is being driven by environmental and health concerns regarding toxicity of lead and, more importantly, by the perceived economic advantage of marketing “green” products. Of the currently available lead free solders, SnAg has the greatest potential. In this solder, the Ag3Sn compound is distributed in a eutectic network throughout the β-Sn matrix and these results represent mechanical strength. In order to further improve the microstructures and properties of SnAg-based alloys, alloying elements such as rare earth, Zn, In, P, Cu, Ni and particles such as ZrO2, POSS are selected to meet the requirement of high reliability of high-density electronics devices. For SnAg solder bearing rare earth (Ce and La), the creep-rupture life of solder joints can be remarkably increased up to four times more than that of the original SnAg solder joints at room temperature, meanwhile, rare earths can dramatically reduce the thickness of IMCs layer at solder/pad interfaces and also refine the microstructure of the alloy which results in the enhancement of mechanical properties of the SnAg solder. Moreover, the addition of ZrO2 nanoparticles significantly refined the size of Ag3Sn due to the adsorption effect of the ZrO2 nanoparticles. This paper summarizes the effects of alloying elements and particles on the wettability, mechanical properties, creep behavior, microstructures, etc. of SnAg-based lead free solder alloys. 相似文献
11.
The creep behaviour of Sn96.5Ag3.5- and Sn95.5Ag3.8Cu0.7-solder was studied specifically for its dependence on technological and environmental factors. The technological factors considered were typical cooling rates and pad metallizations for solder joints in electronic packaging. The environmental factors included microstructural changes as a result of thermal aging of solder joints. Creep experiments were conducted on three types of specimens—flip–chip joints, PCB solder joints and bulk specimens. flip–chip specimens were altered through the selection of various under bump metallizations (Cu vs. NiAu), cooling rates (40 K/min vs. 120 K/min), and thermal storage (24 h, 168 h, and 1176 h at 125 °C). PCB solder joints were studied by using a copper pin soldered into a thru-hole connection on a printed circuit board having a NiAu metallization. Bulk specimens contained the pure alloys. The creep behaviour of the SnAg and SnAgCu solders varied in dependence of specimen type, pad metallization and aging condition. Constitutive models for SnAg and SnAgCu solders as they depend on the reviewed factors are provided. 相似文献
12.
A. Zribi A. Clark L. Zavalij P. Borgesen E. J. Cotts 《Journal of Electronic Materials》2001,30(9):1157-1164
The evolution of intermetallics at and near SnAgCu/Cu and SnAgCu/Ni interfaces was examined, and compared to the behavior,
near PbSn/metal and Sn/metal interfaces. Two different solder compositions were considered, Sn93.6Ag4.7Cu1.7 and Sn95.5Ag3.5Cu1.0 (Sn91.8Ag5.1 Cu3.1 and Sn94.35Ag3.8Cu1.85 in atomic percent). In both cases, phase formation and growth at interfaces with Cu were very similar to those commonly observed
for eutectic SnPb solder. However, the evolution of intermetallics at SnAgCu/Ni interfaces proved much more complex. The presence
of the Cu in the solder dramatically altered the phase selectivity at the solder/Ni interface and affected the growth kinetics
of intermetallics. As long as sufficient Cu was available, it would combine with Ni and Sn to form (Cu,Ni)6)Sn5 which grew instead of the Ni3Sn4 usually observed in PbSn/Ni and Sn/Ni diffusion couples. This growing phase would, however, eventually consume essentially
all of the available Cu in the solder. Because the mechanical properties of Sn-Ag-Cu alloys, depend upon the Cu content, this
consumption can be expected to alter the mechanical properties of these Pb-free solderjoints. After depletion of the Cu from
the solder, further annealing then gradually transformed the (Cu,Ni)6Sn5 phase into a (Ni,Cu)3Sn4 phase. 相似文献
13.
The intermetallic compounds (IMCs) formed during the reflow and aging of Sn3Ag0.5Cu and Sn3Ag0.5Cu0.06Ni0.01Ge solder BGA
packages with Au/Ni surface finishes were investigated. After reflow, the thickness of (Cu, Ni, Au)6Sn5 interfacial IMCs in Sn3Ag0.5Cu0.06Ni0.01Ge was similar to that in the Sn3Ag0.5Cu specimen. The interiors of the solder balls
in both packages contained Ag3Sn precipitates and brick-shaped AuSn4 IMCs. After aging at 150°C, the growth thickness of the interfacial (Ni, Cu, Au)3Sn4 intermetallic layers and the consumption of the Ni surface-finished layer on Cu the pads in Sn3Ag0.5Cu0.06Ni0.01Ge solder
joints were both slightly less than those in Sn3Ag0.5Cu. In addition, a coarsening phenomenon for AuSn4 IMCs could be observed in the solder matrix of Sn3Ag0.5Cu, yet this phenomenon did not occur in the case of Sn3Ag0.5Cu0.06Ni0.01Ge.
Ball shear tests revealed that the reflowed Sn3Ag0.5Cu0.06Ni0.01Ge packages possessed bonding strengths similar to those of
the Sn3Ag0.5Cu. However, aging treatment caused the ball shear strength in the Sn3Ag0.5Cu packages to degrade more than that
in the Sn3Ag0.5Cu0.06Ni0.01Ge packages. 相似文献
14.
Mechanical properties of intermetallic compound (IMC) phases in Pb-free solder joints were obtained using nanoindentation
testing (NIT). The elastic modulus and hardness were determined for IMC phases associated with insitu FeSn particle reinforced
and mechanically added, Cu particle-reinforced, composite solder joints. The IMC layers that formed around Cu particle reinforcement
and at the Cu substrate/solder matrix interface were probed with NIT. Moduli and hardness values obtained by NIT revealed
were noticeably higher for Cu-rich Cu3Sn than those of Cu6Sn5. The Ag3Sn platelets that formed during reflow were also examined for eutectic Sn-Ag solder column joints. The indentation modulus
of Ag3Sn platelets was significantly lower than that of FeSn, SnCuNi, and CuSn IMCs. Indentation creep properties were assessed
in localized microstructure regions of the as-cast, eutectic Sn-Ag solder. The stress exponent, n, associated with secondary
creep differed widely depending on the microstructure feature probed by the indenter tip. 相似文献
15.
SnAgCu is one of the most promising candidates for lead-free solders to replace conventional eutectic SnPb solders. The effects
of solder volume on interfacial reactions and microstructure evolution in Ni/Au-SnAgCu-Ni(P) solder joints have been investigated
under soldering and thermal aging conditions. The results show that solder volume has a strong effect on the formation of
Au-containing intermetallic compounds (IMCs) and their redeposition at the interfaces. The size and volume fraction of Au-containing
IMCs dispersed in the solder bulk increased with decreasing solder joint dimensions. For the small solder joint with 300-μm solder ball, the (Au,Ni)Sn4 IMCs redeposited to the interfaces after thermal aging at 150°C for 9 days, but this was not observed for the other two solder
joints with large solder volume. These results also indicate that the redeposition of (Au,Ni)Sn4 is closely associated with the migration of Cu toward the interfaces. 相似文献
16.
Fan Zhang Ming Li Bavani Balakrisnan William T. Chen 《Journal of Electronic Materials》2002,31(11):1256-1263
The failure mechanisms of SnAgCu solder on Al/Ni(V)/Cu thin-film, underbump metallurgy (UBM) were investigated after multiple
reflows and high-temperature storage using a ball shear test, fracture-surface analysis, and cross-sectional microstructure
examination. The results were also compared with those of eutectic SnPb solder. The Al/Ni (V)/Cu thin-film UBM was found to
be robust enough to resist multiple reflows and thermal aging at conditions used for normal production purposes in both SnAgCu
and eutectic SnPb systems. It was found that, in the SnAgCu system, the failure mode changed with the number of reflows, relating
to the consumption of the thin-film UBM because of the severe interfacial reaction between the solder and the UBM layer. After
high-temperature storage, the solder joints failed inside the solder ball in a ductile manner in both SnAgCu and SnPb systems.
Very fine Ag3Sn particles were formed during multiple reflows in the SnAgCu system. They were found to be able to strengthen the bulk solder.
The dispersion-strengthening effect of Ag3Sn was lost after a short period of thermal aging, caused by the rapid coarsening of these fine particles. 相似文献
17.
Dhafer Abdulameer Shnawah Mohd Faizul Mohd Sabri Irfan Anjum Badruddin Suhana Binti Mohd Said Tadashi Ariga Fa Xing Che 《Journal of Electronic Materials》2013,42(3):470-484
This study compares the high-Ag-content Sn-3Ag-0.5Cu with the low- Ag-content Sn-1Ag-0.5Cu solder alloy and the three quaternary solder alloys Sn-1Ag-0.5Cu-0.1Fe, Sn-1Ag-0.5Cu-0.3Fe, and Sn-1Ag-0.5Cu-0.5Fe to understand the beneficial effects of Fe on the microstructural stability, mechanical properties, and thermal behavior of the low-Ag-content Sn-1Ag-0.5Cu solder alloy. The results indicate that the Sn-3Ag-0.5Cu solder alloy possesses small primary β-Sn dendrites and wide interdendritic regions consisting of a large number of fine Ag3Sn intermetallic compound (IMC) particles. However, the Sn-1Ag-0.5Cu solder alloy possesses large primary β-Sn dendrites and narrow interdendritic regions of sparsely distributed Ag3Sn IMC particles. The Fe-bearing SAC105 solder alloys possess large primary β-Sn dendrites and narrow interdendritic regions of sparsely distributed Ag3Sn IMC particles containing a small amount of Fe. Moreover, the addition of Fe leads to the formation of large circular FeSn2 IMC particles located in the interdendritic regions. On the one hand, tensile tests indicate that the elastic modulus, yield strength, and ultimate tensile strength (UTS) increase with increasing Ag content. On the other hand, increasing the Ag content reduces the total elongation. The addition of Fe decreases the elastic modulus, yield strength, and UTS, while the total elongation is still maintained at the Sn-1Ag-0.5Cu level. The effect of aging on the mechanical behavior was studied. After 720 h and 24 h of aging at 100°C and 180°C, respectively, the Sn-1Ag-0.5Cu solder alloy experienced a large degradation in its mechanical properties after both of the aging conditions, whereas the mechanical properties of the Sn-3Ag-0.5Cu solder alloy degraded more dramatically after 24 h of aging at 180°C. However, the Fe-bearing SAC105 solder alloys exhibited only slight changes in their mechanical properties after both aging procedures. The inclusion of Fe in the Ag3Sn IMC particles suppresses their IMC coarsening, which stabilizes the mechanical properties of the Fe-bearing SAC105 solder alloys after aging. The results from differential scanning calorimetry (DSC) tests indicate that the addition of Fe has a negligible effect on the melting behavior. However, the addition of Fe significantly reduces the solidification onset temperature and consequently increases the degree of undercooling. In addition, fracture surface analysis indicates that the addition of Fe to the Sn-1Ag-0.5Cu alloy does not affect the mode of fracture, and all tested alloys exhibited large ductile dimples on the fracture surface. 相似文献
18.
Aging and accelerated thermal cycling (ATC) have been performed on 2512 chip resistors assembled with Sn3.8Ag0.7Cu (wt.%) solder. The boards were finished with immersion Ag (IAg), electroless nickel/immersion gold (ENIG), and hot air solder leveling Sn–Pb eutectic solder (HASL), and the components’ terminations were finished with 100% Sn and Sn8.0Pb (wt.%). The boards were reflowed with an average cooling rate of 1.6 °C/s. It was found that the microstructure and reliability of the solder joints depended on the board surface finish. The boards containing small amounts of Pb (from board/component terminations) were the most reliable. Solder joints to copper showed a significantly higher number of cycles to first failure than the joints on nickel. Better reliability of the Sn3.8Ag0.7Cu/Cu joints was attributed to an increased copper content in the bulk due to substrate dissolution. 相似文献
19.
To investigate the effect of stand-off height (SOH) on the microstructure and mechanical behavior of certain solder joints,
Cu/Sn9Zn/Cu solder joints with a SOH of 100 μm, 50 μm, 20 μm, and 10 μm were prepared and studied. It was found that, as the SOH is reduced, the Zn content in the solder bulk experiences a rapid
decrease due to consumption by metallurgical reaction in the reflow process; hence, the microstructure of the solder bulk
is changed significantly from a Sn-Zn eutectic structure to a hypoeutectic structure. By contrast, Cu content in the solder
bulk experiences a rapid increase with reducing SOH, and this leads to more dissociative intermetallic compounds (IMCs) in
the solder bulk. These compositional and microstructural changes induced by reducing the SOH correlate closely with the mechanical
properties of the solder joints. In our study it is found that, as SOH is reduced, the tensile strength of the solder joints
decreases, the fracture path of the solder joint transfers from the solder bulk into the interface between the IMC layer and
the solder bulk, and the fracture mode tends to change from ductile to brittle. These findings point to a probable way to
improve the mechanical properties of miniaturized solder joints by controlling the composition and dissociative IMCs in the
solder bulk. 相似文献
20.
B. Dompierre W.C. Maia Filho M. Brizoux V. Aubin E. Charkaluk 《Microelectronics Reliability》2010,50(9-11):1661-1665
For the SnAgCu alloys, previous hardness test results suggested that high temperature thermal ageing causes a quick and significant drop in the mechanical properties. However, to date, the acceleration law of thermal ageing and the relationship between thermal ageing and fatigue mechanical behavior of SnAgCu alloys are still unknown.The aim of this paper is to understand the mechanical changes during thermal ageing of Sn3.0Ag0.5Cu alloy and their impact on solder joint reliability under mechanical stresses. In a first part, influence of thermal ageing on mechanical behavior is analyzed by means of hardness tests, reversed tensile tests on dog-bone specimens and compression test on solder balls used for electronic components. In the second part, the impact of thermal ageing on the solder joint reliability is analyzed thanks to torsion tests on assembled boards.The results show systematically a decrease of 20–60% of the mechanical properties or of the number of cycles to failure (in the case of torsion test). These results lead to enlarge tests conditions in order to define the fields where the influence of thermal ageing cannot be neglected. 相似文献