共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
The effect of surface roughness of copper substrate on the reactive wetting of Sn-Ag-Cu solder alloys and morphology of intermetallic compounds (IMCs) was investigated. The spreading behavior of solder alloys on smooth and rough Cu substrates was categorized into capillary, diffusion/reaction, and contact angle stabilization zones. The increase in substrate surface roughness improved the wetting of solder alloys, being attributed to the presence of thick Cu3Sn IMC at the interface. The morphology of IMCs transformed from long needle shaped to short protruded type with an increase in the substrate surface roughness for the Sn-0.3Ag-0.7Cu and Sn-3Ag-0.5Cu solder alloys. However, for the Sn-2.5Ag-0.5Cu solder alloy the needle-shaped IMCs transformed to the completely scallop type with increase in the substrate surface roughness. The effect of Ag content on wetting behavior was not significant. 相似文献
3.
S. Lotfian J.M. Molina-Aldareguia K.E. Yazzie J. Llorca N. Chawla 《Journal of Electronic Materials》2013,42(6):1085-1091
The reliability of Pb-free solder joints is controlled by their microstructural constituents. Therefore, knowledge of the solder microconstituents’ mechanical properties as a function of temperature is required. Sn-Ag-Cu lead-free solder alloy contains three phases: a Sn-rich phase, and the intermetallic compounds (IMCs) Cu6Sn5 and Ag3Sn. Typically, the Sn-rich phase is surrounded by a eutectic mixture of β-Sn, Cu6Sn5, and Ag3Sn. In this paper, we report on the Young’s modulus and hardness of the Cu6Sn5 and Cu3Sn IMCs, the β-Sn phase, and the eutectic compound, as measured by nanoindentation at elevated temperatures. For both the β-Sn phase and the eutectic compound, the hardness and Young’s modulus exhibited strong temperature dependence. In the case of the intermetallics, this temperature dependence is observed for Cu6Sn5, but the mechanical properties of Cu3Sn are more stable up to 200°C. 相似文献
4.
Sn-Ag-Cu composite solders reinforced with nano-sized, nonreacting, noncoarsening 1 wt% TiO2 particles were prepared by mechanically dispersing TiO2 nano-particles into Sn-Ag-Cu solder powder and the interfacial morphology of the solder and flexible BGA substrates were characterized metallographically. At their interfaces, different types of scallop-shaped intermetallic compound layers such as Cu6Sn5 for a Ag metallized Cu pad and Sn-Cu-Ni for a Au/Ni and Ni metallized Cu pad, were found in plain Sn-Ag-Cu solder joints and solder joints containing 1 wt% TiO2 nano-particles. In addition, the intermetallic compound layer thicknesses increased substantially with the number of reflow cycles. In the solder ball region, Ag3Sn, Cu6Sn5 and AuSn4 IMC particles were found to be uniformly distributed in the β-Sn matrix. However, after the addition of TiO2 nano-particles, Ag3Sn, AuSn4 and Cu6Sn5 IMC particles appeared with a fine microstructure and retarded the growth rate of IMC layers at their interfaces. The Sn-Ag-Cu solder joints containing 1 wt% TiO2 nano-particles consistently displayed a higher hardness than that of the plain Sn-Ag-Cu solder joints as a function of the number of reflow cycles due to the well-controlled fine microstructure and homogeneous distribution of TiO2 nano-particles which gave a second phase dispersion strengthening mechanism. 相似文献
5.
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
6.
Yee-Wen Yen Weng-Ting Chou Yu Tseng Chiapyng Lee Chun-Lei Hsu 《Journal of Electronic Materials》2008,37(1):73-83
This study investigates the dissolution behavior of the metallic substrates Cu and Ag and the intermetallic compound (IMC)-Ag3Sn in molten Sn, Sn-3.0Ag-0.5Cu, Sn-58Bi and Sn-9Zn (in wt.%) at 300, 270 and 240°C. The dissolution rates of both Cu and
Ag in molten solder follow the order Sn > Sn-3.0Ag-0.5Cu >Sn-58Bi > Sn-9Zn. Planar Cu3Sn and scalloped Cu6Sn5 phases in Cu/solders and the scalloped Ag3Sn phase in Ag/solders are observed at the metallic substrate/solder interface. The dissolution mechanism is controlled by
grain boundary diffusion. The planar Cu5Zn8 layer formed in the Sn-9Zn/Cu systems. AgZn3, Ag5Zn8 and AgZn phases are found in the Sn-9Zn/Ag system and the dissolution mechanism is controlled by lattice diffusion. Massive
Ag3Sn phases dissolved into the solders and formed during solidification processes in the Ag3Sn/Sn or Sn-3.0Ag-0.5Cu systems. AgZn3 and Ag5Zn8 phases are formed at the Sn-9Zn/Ag3Sn interface. Zn atoms diffuse through Ag-Zn IMCs to form (Ag, Zn)Sn4 and Sn-rich regions between Ag5Zn8 and Ag3Sn. 相似文献
7.
Lead-free solder bumps have been widely used in current flip-chip technology (FCT) due to environmental issues. Solder joints
after temperature cycling tests were employed to investigate the interfacial reaction between the Ti/Ni/Cu under-bump metallization
and Sn-Ag-Cu solders. The interfacial morphology and quantitative analysis of the intermetallic compounds (IMCs) were obtained
by electron probe microanalysis (EPMA) and field emission electron probe microanalysis (FE-EPMA). Various types of IMCs such
as (Cu1−x,Agx)6Sn5, (Cu1−y,Agy)3Sn, and (Ag1−z,Cuz)3Sn were observed. In addition to conventional I–V measurements by a special sample preparation technique, a scanning electron
microscope (SEM) internal probing system was introduced to evaluate the electrical characteristics in the IMCs after various
test conditions. The electrical data would be correlated to microstructural evolution due to the interfacial reaction between
the solder and under-bump metallurgy (UBM). This study demonstrated the successful employment of an internal nanoprobing approach,
which would help further understanding of the electrical behavior within an IMC layer in the solder/UBM assembly. 相似文献
8.
9.
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
10.
The solder joint microstructures of immersion Ag with Sn-xZn (x = 0 wt.%, 1 wt.%, 5 wt.%, and 9 wt.%) solders were analyzed and correlated with their drop impact reliability. Addition of
1 wt.% Zn to Sn did not change the interface microstructure and was only marginally effective. In comparison, the addition
of 5 wt.% or 9 wt.% Zn formed layers of AgZn3/Ag5Zn8 at the solder joint interface, which increased drop reliability significantly. Under extensive aging, Ag-Zn intermetallic
compounds (IMCs) transformed into Cu5Zn8 and Ag3Sn, and the drop impact resistance at the solder joints deteriorated up to a point. The beneficial role of Zn on immersion
Ag pads was ascribed to the formation of Ag-Zn IMC layers, which were fairly resistant to the drop impact, and to the suppression
of the brittle Cu6Sn5 phase at the joint interface. 相似文献
11.
The Sn-3.5Ag-0.5Cu (wt.%) is the most promising replacement for the eutectic tin-lead solder alloy. Here, an investigation
has been carried out to compare the interfacial reactions of the Cu pad of a ball grid array (BGA) substrate with molten eutectic
Sn-3.5% Ag-0.5% Cu solder having different volumes. Two different sizes of BGA solder balls were used: 760-μm and 500-μm diameter.
Scanning electron microscopy (SEM) was used to measure the consumed thickness of the Cu and also the thickness of the intermetallic
compound (IMC). The soldering reaction was carried out at 230°C, 240°C, and 250°C for 1 min, 5 min, 10 min, and 20 min. The
Cu consumption was much higher for the Sn-Ag-Cu solder with higher volume. On the other hand, the mean thickness of the intermetallics
for solder with smaller volume was thicker than that of the bigger solder balls. The Cu3Sn compound was also observed at the interface between the Cu6Sn5 IMCs and Cu substrate for longer reflow for the both solder balls. Larger Cu6Sn5 IMCs were observed in the bulk of the solder with bigger volume. A simplistic theoretical approach is carried out to find
out the amount of Cu6Sn5 IMCs in the bulk of the solder by measurement of the Cu consumption from the substrate and the thickness of the IMCs that
form on the interface. 相似文献
12.
J. Chriaštel’ová L. Rízeková Trnková K. Pocisková Dimová M. Ožvold 《Journal of Electronic Materials》2011,40(9):1956-1961
Small amounts of the rare-earth element Ce were added to the Sn-rich lead-free eutectic solders Sn-3.5Ag-0.7Cu, Sn-0.7Cu,
and Sn-3.5Ag to improve their properties. The microstructures of the solders without Ce and with different amounts (0.1 wt.%,
0.2 wt.%, and 0.5 wt.%) of Ce were compared. The microstructure of the solders became finer with increasing Ce content. Deviation
from this rule was observed for the Sn-Ag-Cu solder with 0.2 wt.% Ce, and for the Sn-0.7Cu eutectic alloy, which showed the
finest microstructure without Ce. The melting temperatures of the solders were not affected. The morphology of intermetallic
compounds (IMC) formed at the interface between the liquid solders and a Cu substrate at temperatures about 40°C above the
melting point of the solder for dipping times from 2 s to 256 s was studied for the basic solder and for solder with 0.5 wt.%
Ce addition. The morphology of the Cu6Sn5 IMC layer developed at the interface between the solders and the substrate exhibited the typical scallop-type shape without
significant difference between solders with and without Ce for the shortest dipping time. Addition of Ce decreased the thickness
of the Cu6Sn5 IMC layer only at the Cu/Sn-Ag-Cu solder interface for the 2-s dipping. A different morphology of the IMC layer was observed
for the 256-s dipping time: The layers were less continuous and exhibited a broken relief. Massive scallops were not observed.
For longer dipping times, Cu3Sn IMC layers located near the Cu substrate were also observed. 相似文献
13.
Microstructural modifications and properties of Sn-Ag-Cu solder joints induced by alloying 总被引:1,自引:0,他引:1
I. E. Anderson B. A. Cook J. Harringa R. L. Terpstra 《Journal of Electronic Materials》2002,31(11):1166-1174
Slow cooling (1–3°C/sec) of Sn-Ag-Cu and Sn-Ag-Cu-X (X = Fe, Co) solder-joint specimens, made by hand soldering, simulated
reflow in a surface-mount assembly to achieve similar as-solidified joint microstructures for realistic shear-strength testing,
using Sn-3.5Ag (wt.%) as a baseline. Consistent with predictions from a recent Sn-Ag-Cu ternary phase-diagram study, either
Sn dendrites, Ag3Sn primary phase, or Cu6Sn5 primary phase were formed during solidification of joint samples made from the selected near-eutectic Sn-Ag-Cu alloys. Minor
substitution of Co for Cu in Sn-3.7Ag-0.9Cu refined the joint-matrix microstructure by an apparent catalysis effect on the
Cu6Sn5 phase, whereas Fe substitution promoted extreme refinement of the Sn-dendritic phase. Ambient-temperature shear strength
was reduced by Sn dendrites in the joint microstructure, especially coarse dendrites in solute poor Sn-Ag-Cu, e.g., Sn-3.0Ag-0.5Cu,
while Sn-3.7Ag-0.9Cu with Co and Fe additions have increased shear strength. At elevated (150°C) temperature, no significant
difference exists between the maximum shear-strength values of all of the alloys studied. 相似文献
14.
Hwa-Teng Lee Choo-Yeow Lee Fok-Foo Lee Yin-Fa Chen Yang-Hsien Lee 《Journal of Electronic Materials》2009,38(10):2112-2121
The effects of 1 wt.%, 5 wt.%, and 10 wt.% additions of indium (In) on the microstructure and compound morphology of Sn-Ag-Sb
lead-free solder joints␣were examined. The results showed that In prompts the formation of Ag3(Sn,In), Ag2(In,Sn), and InSb compounds within the solder matrix. As the amount of In was increased, the Sn atoms in the Ag3Sn compound were gradually replaced by In atoms, prompting a transformation from Ag3Sn to Ag3(Sn,In) and finally to Ag2(In,Sn). This transformation occurs more readily under high-temperature conditions. The Ag2(In,Sn) compound formed in Sn-Ag-Sb-xIn/Cu solder joints was found to have either a leaf-like morphology or an antler-like morphology. Finally, with In additions
greater than 5 wt.%, the Cu6Sn5 interfacial compounds in the solder/Cu joints transformed into Cu6(Sn,In)5. 相似文献
15.
Hai-Tao Ma Jie Wang Lin Qu Ning Zhao A. Kunwar 《Journal of Electronic Materials》2013,42(8):2686-2695
A rapidly solidified Sn-3.5Ag eutectic alloy produced by the melt-spinning technique was used as a sample in this research to investigate the microstructure, thermal properties, solder wettability, and inhibitory effect of Ag3Sn on Cu6Sn5 intermetallic compound (IMC). In addition, an as-cast Sn-3.5Ag solder was prepared as a reference. Rapidly solidified and as-cast Sn-3.5Ag alloys of the same size were soldered at 250°C for 1 s to observe their instant melting characteristics and for 3 s with different cooling methods to study the inhibitory effect of Ag3Sn on Cu6Sn5 IMC. Experimental techniques such as scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectrometry were used to observe and analyze the results of the study. It was found that rapidly solidified Sn-3.5Ag solder has more uniform microstructure, better wettability, and higher melting rate as compared with the as-cast material; Ag3Sn nanoparticles that formed in the rapidly solidified Sn-3.5Ag solder inhibited the growth of Cu6Sn5 IMC during aging significantly much strongly than in the as-cast material because their number in the rapidly solidified Sn-3.5Ag solder was greater than in the as-cast material with the same soldering process before aging. Among the various alternative lead-free solders, this study focused on comparison between rapidly solidified and as-cast solder alloys, with the former being observed to have better properties. 相似文献
16.
Zn additions to Cu under bump metallurgy (UBM) in solder joints were the subject of this study. An alternative design was
implemented to fabricate pure Sn as the solder and Cu-xZn (x = 15 wt.% and 30 wt.%) as the UBM to form the reaction couple. As the Zn content increased from 15 wt.% to 30 wt.% in the
Sn/Cu-Zn system, growth of both Cu3Sn and Cu6Sn5 was suppressed. In addition, no Kirkendall voids were observed at the interface in either Sn/Cu-Zn couple during heat treatment.
After 40-day aging, different multilayered phases of [Cu6Sn5/Cu3Sn/Cu(Zn)] and [Cu6Sn5/Cu(Zn,Sn)/CuZn] formed at the interface of [Sn/Cu-15Zn] and [Sn/Cu-30Zn] couples, respectively. The growth mechanism of intermetallic
compounds (IMCs) during aging is discussed on the basis of the composition variation in the joint assembly with the aid of
electron-microscopic characterization and the Sn-Cu-Zn ternary phase diagram. According to these analyses of interfacial morphology
and IMC formation in the Sn/Cu-Zn system, Cu-Zn is a potential UBM for retarding Cu pad consumption in solder joints. 相似文献
17.
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
18.
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
19.
The shear strength behavior and microstructural effects after aging for 100 h and 1,000 h at 150°C are reported for near-eutectic
Sn-Ag-Cu (SAC) solder joints (joining to Cu) made from Sn-3.5Ag (wt.%) and a set of SAC alloys (including Co- and Fe-modified
SAC alloys). All joints in the as-soldered and 100-h aged condition experienced shear failure in a ductile manner by either
uniform shear of the solder matrix (in the strongest solders) or by a more localized shear of the solder matrix adjacent to
the Cu6Sn5 interfacial layer, consistent with other observations. After 1,000 h of aging, a level of embrittlement of the Cu3Sn/Cu interface can be detected in some solder joints made with all of the SAC alloys and with Sn-3.5Ag, which can lead to
partial debonding during shear testing. However, only ductile failure was observed in all solder joints made from the Co-
and Fe-modified SAC alloys after aging for 1,000 h. Thus, the strategy of modifying a strong (high Cu content) SAC solder
alloy with a substitutional alloy addition for Cu seems to be effective for producing a solder joint that retains both strength
and ductility for extended isothermal aging at high temperatures. 相似文献
20.
In general, formation and growth of intermetallic compounds (IMCs) play a major role in the reliability of the solder joint
in electronics packaging and assembly. The formation of Cu-Sn or Ni-Sn IMCs have been observed at the interface of Sn-rich
solders reacted with Cu or Ni substrates. In this study, a nanoindentation technique was employed to investigate nanohardness
and reduced elastic moduli of Cu6Sn5, Cu3Sn, and Ni3Sn4 IMCs in the solder joints. The Sn-3.5Ag and Sn-37Pb solder pastes were placed on a Cu/Ti/Si substrate and Ni foil then annealed
at 240°C to fabricate solder joints. In Sn-3.5Ag joints, the magnitude of the hardness of the IMCs was in the order Ni3Sn4>Cu6Sn5>Cu3Sn, and the elastic moduli of Cu6Sn5, Cu3Sn, and Ni3Sn4 were 125 GPa, 136 GPa, and 142 GPa, respectively. In addition, the elastic modulus of the Cu6Sn5 IMC in the Sn-37Pb joint was similar to that for the bulk Cu6Sn5 specimen but less than that in the Sn-3.5Ag joint. This might be attributed to the strengthening effect of the dissolved
Ag atoms in the Cu6Sn5 IMC to enhance the elastic modulus in the Sn-3.5Ag/Cu joint. 相似文献