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1.
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
2.
The 0.2Co + 0.1Ni dual additives were used to dope a Sn-3.5Ag solder matrix to modify the alloy microstructure and the solder
joint on an organic solderability preservative (OSP) Cu pad. The refined microstructure of the Sn-3.5Ag-0.2Co-0.1Ni solder
alloy or the reduced β-Sn size was attributed to the depressed undercooling achieved by the Co-Ni addition. After soldering
on the OSP Cu pad, a large Ag3Sn plate was formed at the Sn-3.5Ag/OSP solder joint, whereas it was absent at the Sn-3.5Ag-0.2Co-0.1Ni/OSP solder joints.
With isothermal aging at 150°C, large Ag3Sn plates formed at the Sn-3.5Ag/OSP solder joint were still observed. A coarsened and dispersed Ag3Sn phase was found in the solder joints with Co-Ni additions as well. Compared to Cu6Sn5, the (Co,Ni)Sn2 intermetallic compound showed much lower microhardness values. However, (Co,Ni)Sn2 hardness was comparable to that of the Ag3Sn phase. Pull strength testing of Sn-3.5Ag-0.2Co-0.1Ni/OSP revealed slightly lower values than for Sn-3.5Ag/OSP during aging.
Such results are thought be due to the phase transformation of (Co,Ni)Sn2 to (Cu,Co,Ni)6Sn5. 相似文献
3.
The intermetallic compounds formed in Sn3Ag0.5Cu and Sn3Ag0.5Cu0.06Ni0.01Ge solder BGA packages with Ag/Cu pads are investigated.
After reflow, scallop-shaped η-Cu6Sn5 and continuous planar η-(cu0.9Ni0.1)6Sn5 intermetallics appear at the interfaces of the Sn3Ag0.5Cu and Sn3Ag0.5Cu0.06Ni0.01Ge solder joints, respectively. In the
case of the Sn3Ag0.5Cu specimens, an additional ε-Cu3Sn intermetallic layer is formed at the interface between the η-Cu6Sn5 and Cu pads after aging at 150°C, while the same type of intermetallic formation is inhibited in the Sn3Ag0.5Cu0.06Ni0.01Ge
packages. In addition, the coarsening of Ag3Sn precipitates also abates in the solder matrix of the Sn3Ag0.5Cu0.06Ni0.01Ge packages, which results in a slightly higher
ball shear strength for the specimens. 相似文献
4.
During the reflowing of Sn-9Zn solder ball grid array (BGA) packages with Au/Ni/Cu and Ag/Cu pads, the surface-finished Au
and Ag film dissolved rapidly and reacted with the Sn-9Zn solder to form a γ3-AuZn4/γ-Au7Zn18 intermetallic double layer and ε-AgZn6 intermetallic scallops, respectively. The growth of γ3-AuZn4 is prompted by further aging at 100°C through the reaction of γ-Au7Zn18 with the Zn atoms dissolved from the Zn-rich precipitates embedded in the β-Sn matrix of Sn-9Zn solder BGA with Au/Ni/Cu
pads. No intermetallic compounds can be observed at the solder/pad interface of the Sn-9Zn BGA specimens aged at 100°C. However,
after aging at 150°C, a Ni4Zn21 intermetallic layer is formed at the interface between Sn-9Zn solder and Ni/Cu pads. Aging the immersion Ag packages at 100°C
and 150°C caused a γ-Cu5Zn8 intermetallic layer to appear between ε-AgZn6 intermetallics and the Cu pad. The scallop-shaped ε-AgZn6 intermetallics were found to detach from the γ-Cu5Zn8 layer and float into the solder ball. Accompanied with the intermetallic reactions during the aging process of reflowed Sn-9Zn
solder BGA packages with Au/Ni/Cu and Ag/Cu pads, their ball shear strengths degrade from 8.6 N and 4.8 N to about 7.2 N and
2.9 N, respectively. 相似文献
5.
As-cast Sn-0.4Co-0.7Cu solder contains both (Cu0.98Co0.02)6Sn5 and (Co0.85Cu0.15) Sn3 intermetallic phases in the matrix. After reflowing, the Au thin film in the electroless Ni/immersion Au (ENIG) surface-finished
Sn-0.4Co-0.7Cu solder ball grid array (BGA) packages dissolved rapidly into the solder matrix to form AuSn4 intermetallics, and a thin layer of (Cu0.57Ni0.35Au0.08)6Sn5 intermetallic compound appeared at the solder/pad interface, growing very slowly during aging at 100°C. Increasing the aging
temperature to 150°C caused the formation of a new intermetallic layer, (Ni0.79Cu0.21)3Sn4, at the (Cu0.57Ni0.35Au0.08)6Sn5/Ni interface. The reflowed Sn-0.4Co-0.7Cu BGA packages have a ball shear strength of 6.8 N, which decreases to about 5.7 N
and 5.5 N after aging at 100°C and 150°C, respectively. The reflowed and aged solder joints fractured across the solder balls
with ductile characteristics in ball shear tests. 相似文献
6.
The intermetallic compounds formed during the reflow and aging of Sn-20In-2.8Ag ball-grid-array (BGA) packages are investigated.
After reflow, a large number of cubic-shaped AuIn2 intermetallics accompanied by Ag2In precipitates appear in the solder matrix, while a Ni(Sn0.72Ni0.28)2 intermetallic layer is formed at the solder/pad interface. With further aging at 100°C, many voids can be observed in the
solder matrix and at the solder/pad interface. The continuous distribution of voids at the interface of specimens after prolonged
aging at 100°C causes their bonding strength to decrease from 5.03 N (as reflowed) to about 3.50 N. Aging at 150°C induces
many column-shaped (Cu0.74Ni0.26)6(Sn0.92In0.08)5 intermetallic compounds to grow rapidly and expand from the solder/pad interface into the solder matrix. The high microhardness
of these intermetallic columns causes the bonding strength of the Sn-20In-2.8Ag BGA solder joints to increase to 5.68 N after
aging at 150°C for 500 h. 相似文献
7.
Chin-Su Chi Hen-So Chang Ker-Chang Hsieh C. L. Chung 《Journal of Electronic Materials》2002,31(11):1203-1207
Ball-grid array (BGA) samples were aged at 155°C up to 45 days. The formation and the growth of the intermetallic phases at
the solder joints were investigated. The alloy compositions of solder balls included Sn-3.5Ag-0.7Cu, Sn-1.0Ag-0.7Cu, and 63Sn-37Pb.
The solder-ball pads were a copper substrate with an Au/Ni surface finish. Microstructural analysis was carried out by electron
microprobe. The results show that a ternary phase, (Au,Ni)Sn4, formed with Ni3Sn4 in the 63Sn-37Pb solder alloy and that a quaternary intermetallic phase, (Au,Ni)2Cu3Sn5, formed in the Sn-Ag-Cu solder alloys. The formation mechanism of intermetallic phases was associated with the driving force
for Au and Cu atoms to migrate toward the interface during aging. 相似文献
8.
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
9.
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
10.
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
11.
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
12.
Yu-Chih Liu Wei-Hong Lin Hsiu-Jen Lin Tung-Han Chuang 《Journal of Electronic Materials》2006,35(1):147-153
During the reflow process of Sn-8Zn-20In solder joints in the ball grid array (BGA) packages with Au/Ni/Cu and Ag/Cu pads,
the Au and Ag thin films react with liquid solder to form γ3-AuZn4/γ-Au7Zn18 and ε-AgZn6 intermetallics, respectively. The γ3/γ intermetallic layer is prone to floating away from the solder/Ni interface, and the appearance of any interfacial intermetallics
cannot be observed in the Au/Ni surface finished Sn-8Zn-20In packages during further aging treatments at 75°C and 115°C. In
contrast, ε-CuZn5/γ-Cu5Zn8 intermetallics are formed at the aged Sn-8Zn-20In/Cu interface of the immersion Ag BGA packages. Bonding strengths of 3.8N
and 4.0N are found in the reflowed Sn-8Zn-20In solder joints with Au/Ni/Cu and Ag/Cu pads, respectively. Aging at 75°C and
115°C gives slight increases of ball shear strength for both cases. 相似文献
13.
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
14.
Chi-Won Hwang Katsuaki Suganuma Masayuki Kiso Shigeo Hashimoto 《Journal of Electronic Materials》2004,33(10):1200-1209
The formation and growth of intermetallics at the interface between Sn-Ag-(Cu) alloy balls and Au/Ni-6P plating were experimentally
examined as a function of soldering period. Joint strengths were also evaluated by a ball pull test. For the joint with Sn-3.5Ag,
the primary reaction product of Ni3Sn4 exhibits growth and shrinkage in thickness repeatedly with a passage of reaction time up to 30 min, while the Ni3SnP reaction layer monotonously increases its thickness without fluctuation. In the cases of the joints with Cu bearing solder,
Sn-3Ag-0.5Cu and Sn-3.5Ag-0.8Cu, a single η-(Cu,Ni)6Sn5 interface layer grows by fast Cu segregation from liquid solder to the interface layer on soldering. For all the soldered
joints, a P-rich layer appears at the surface region of a Ni-6P plating layer by Ni depletion to form those intermetallic
compounds at interfaces. The growth rate of a P-rich layer for Sn-3.5Ag is faster by about 4–8 times than those of the Sn-Ag-Cu.
The presence of Cu in solder enhances the formation of the Cu6Sn5 intermetallic layer at the interface resulting in prevention of Ni diffusion to liquid solder. For all the soldered joints,
coarsened reaction interfaces decrease the joint strengths. 相似文献
15.
After reflow of Sn-3.8Ag-0.7Cu and Sn-20In-2Ag-0.5Cu solder balls on Au/Ni surface finishes in ball grid array (BGA) packages,
scallop-shaped intermetallic compounds (Cu0.70Ni0.28Au0.02)6Sn5 (IM1a) and (Cu0.76Ni0.24)6(Sn0.86In0.14)5 (IM1b), respectively, appear at the interfaces. Aging at 100°C and 150°C for Sn-3.8Ag-0.7Cu results in the formation of a
new intermetallic phase (Cu0.70Ni0.14Au0.16)6Sn5 (IM2a) ahead of the former IM1a intermetallics. The growth of the newly appeared intermetallic compound, IM2a, is governed
by a parabolic relation with an increase in aging time, with a slight diminution of the former IM1a intermetallics. After
prolonged aging at 150°C, the IM2a intermetallics partially spall off and float into the solder matrix. Throughout the aging
of Sn-20In-2Ag-.5Cu solder joints at 75°C and 115°C, partial spalling of the IM1b interfacial intermetallics induces a very
slow increase in thickness. During aging at 115°C for 700 h through 1,000 h, the spalled IM1b intermetallics in the solder
matrix migrate back to the interfaces and join with the IM1b interfacial intermetallics to react with the Ni layers of the
Au/Ni surface finishes, resulting in the formation and rapid growth of a new (Ni0.85Cu0.15)(Sn0.71In0.29)2 intermetallic layer (IM2b). From ball shear tests, the strengths of the Sn-3.8Ag-0.7Cu and Sn-20In-2Ag-0.5Cu solder joints
after reflow are ascertained to be 10.4 N and 5.4 N, respectively, which drop to lower values after aging.
An erratum to this article is available at . 相似文献
16.
Extensive microstructural and kinetic studies on the formation and growth of the intermetallics of Sn-rich solder/Cu couples
have been reported. However, experimental data on the interdiffusion mechanisms during soldering reactions are limited and
in conflict. The interdiffusion processes for soldering of Sn-3.5Ag alloy/Cu couples were investigated by using the Cr-evaporated
surface as a reference line. At the beginning of soldering, Cu was observed to outdiffuse to the molten Sn−3.5Ag alloy until
saturation, and the Sn−Ag solder dissolved with Cu collapsed below the reference line. As a result, the scallop-shaped Cu6Sn5 intermetallic compound was formed at the newly-formed Sn−Ag−Cu solder/Cu interface below the original Cu surface. When the
soldered joint was reflowed at the lower temperature to suppress the Cu dissolution, the Cu6Sn5/Cu interface moved into the Cu substrate. Therefore, Sn is the dominant diffusing species for the intermetallic formation
during the soldering process, although the extensive Cu dissolution occurs at the early stage of soldering. 相似文献
17.
Growth of an intermetallic compound layer with Sn-3.5Ag-5Bi on Cu and Ni-P/Cu during aging treatment
Growth kinetics of intermetallic compound (IMC) layers formed between the Sn-3.5Ag-5Bi solder and the Cu and electroless Ni-P
substrates were investigated at temperatures ranging from 70°C to 200°C for 0–60 days. With the solder joints between the
Sn-Ag-Bi solder and Cu substrates, the IMC layer consisted of two phases: the Cu6Sn5 (η phase) adjacent to the solder and the Cu3Sn (ε phase) adjacent to the Cu substrate. In the case of the electroless Ni-P substrate, the IMC formed at the interface
was mainly Ni3Sn4, and a P-rich Ni (Ni3P) layer was also observed as a by-product of the Ni-Sn reaction, which was between the Ni3Sn4 IMC and the electroless Ni-P deposit layer. With all the intermetallic layers, time exponent (n) was approximately 0.5, suggesting
a diffusion-controlled mechanism over the temperature range studied. The interface between electroless Ni-P and Ni3P was planar, and the time exponent for the Ni3P layer growth was also 0.5. The Ni3P layer thickness reached about 2.5 μm after 60 days of aging at 170°C. The activation energies for the growth of the total
Cu-Sn compound layer (Cu6Sn5 + Cu3Sn) and the Ni3Sn4 IMC were 88.6 kJ/mol and 52.85 kJ/mol, respectively. 相似文献
18.
G. Ghosh 《Journal of Electronic Materials》2000,29(10):1182-1193
A comparative study of the kinetics of interfacial reaction between the eutectic solders (Sn-3.5Ag, Sn-57Bi, and Sn-38Pb)
and electroplated Ni/Pd on Cu substrate (Cu/Ni/NiPd/Ni/Pd) was performed. The interfacial microstructure was characterized
by imaging and energy dispersive x-ray analysis in scanning electron microscope (SEM). For a Pd-layer thickness of less than
75 nm, the presence or the absence of Pd-bearing intermetallic was found to be dependent on the reaction temperature. In the
case of Sn-3.5Ag solder, we did not observe any Pd-bearing intermetallic after reaction even at 230°C. In the case of Sn-57Bi
solder the PdSn4 intermetallic was observed after reaction at 150°C and 180°C, while in the case of Sn-38Pb solder the PdSn4 intermetallic was observed after reaction only at 200°C. The PdSn4 grains were always dispersed in the bulk solder within about 10 μm from the solder/substrate interface. At higher reaction
temperatures, there was no Pd-bearing intermetallic due to increased solubility in the liquid solder. The presence or absence
of Pd-bearing intermetallic was correlated with the diffusion path in the calculated Pd-Sn-X (X=Ag, Bi, Pb) isothermal sections.
In the presence of unconsumed Ni, only Ni3Sn4 intermetallic was observed at the solder-substrate interface by SEM. The presence of Ni3Sn4 intermetallic was consistent with the expected diffusion path based on the calculated Ni-Sn-X (X=Ag, Bi, Pb) isothermal sections.
Selective etching of solders revealed that Ni3Sn4 had a faceted scallop morphology. Both the radial growth and the thickening kinetics of Ni3Sn4 intermetallic were studied. In the thickness regime of 0.14 μm to 1.2 μm, the growth kinetics always yielded a time exponent
n >3 for liquid-state reaction. The temporal law for coarsening also yielded time exponent m >3. The apparent activation energies
for thickening were: 16936J/mol for the Sn-3.5Ag solder, 17804 J/mol for the Sn-57Bi solder, and 25749 J/mol for the Sn-38Pb
solder during liquid-state reaction. The corresponding activation energies for coarsening were very similar. However, an apparent
activation energy of 37599 J/mol was obtained for the growth of Ni3Sn4 intermetallic layer during solid-state aging of the Sn-57Bi/substrate diffusion couples. The kinetic parameters associated
with thickening and radial growth were discussed in terms of current theories. 相似文献
19.
The interfacial reactions between Sn-3.0 Ag-0.7 Cu solder and backside metallizations on two semiconductor devices, field-effect
transistors (FET) and diode, are studied. The metallizations on both devices were vacuum evaporated Ti/Ni/Ag. The intermetallic
compounds (IMC) formed near the diode/solder and FET/solder joints during reflow, and the interdiffusion processes during
solid state aging are characterized by the quantitative energy dispersive x-ray analysis and the x-ray mapping technique in
a scanning electron microscope. Two different intermetallic compounds are found near the diode/solder interface. Both are
in the form of particles, not a continuous layer, and are referred to as IMC-I and IMC-II. IMC-I corresponds to Ni3Sn4, with Cu atoms residing on the Ni sublattice. It is uncertain whether IMC-II is Cu6Sn5 or a Cu-Ni-Sn ternary phase. Near the as-reflowed FET/solder interface, both isolated scallops and a skeleton-like layer
of Ni3Sn4 are observed. The primary microstructural dynamics during solid-state aging are the coarsening of IMCs and the reactions
involving the Ni-and Ti-layer with Sn and Au. While the reaction with the Ni-layer yields only Ni3Sn4 intermetallic, the reaction involving the Ti-layer suggests the formation of Ti-Sn and Au-Sn-Ti intermetallics. The latter
is due to the diffusion of Au from the substrate side to the die side. It is postulated that the kinetics of the Au-Sn-Ti
layer is primarily governed by the diffusion of Au through the Ni3Sn4 layer by a grain boundary mechanism. 相似文献
20.
T. H. Chuang H. M. Wu M. D. Cheng S. Y. Chang S. F. Yen 《Journal of Electronic Materials》2004,33(1):22-27
Intermetallic compounds formed during the soldering reactions between Sn-3.5Ag and Cu at temperatures ranging from 250°C to
375°C are investigated. The results indicate that scallop-shaped η-Cu6(Sn0.933 Ag0.007)5 intermetallics grow from the Sn-3.5Ag/Cu interface toward the solder matrix accompanied by Cu dissolution. Following prolonged
or higher temperature reactions, ɛ-Cu3 (Sn0.996 Ag0.004) intermetallic layers appear behind the Cu6(Sn0.933 Ag0.007)5 scallops. The growth of these interfacial intermetallics is governed by a kinetic relation: ΔX=tn, where the n values for η and ɛ intermetallics are 0.75 and 0.96, respectively. The mechanisms for such nonparabolic growth
of interfacial intermetallics during the liquid/solid reactions between Sn-3.5Ag solders and Cu substrates are probed. 相似文献