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1.
The microstructure of the ultrasmall eutectic Bi-Sn solder bumps on Au/Cu/Ti and Au/Ni/Ti under-bump metallizations (UBMs)
was investigated as a function of cooling rate. The ultrasmall eutectic Bi-Sn solder bump, about 50 μm in diameter, was fabricated
by using the lift-off method and reflowed at various cooling rates using the rapid thermal annealing system. The microstructure
of the solder bump was observed using a backscattered electron (BSE) image and the intermetallic compound was identified using
energy dispersive spectroscopy (EDS) and an x-ray diffractometer (XRD). The Bi facet was found at the surface of the ultrasmall
Bi-Sn solder bumps on the Au/Cu/Ti UBM in almost all specimens, and the interior microstructure of the bumps was changed with
the solidification rate. The faceted and polygonal intermetallic compound was found in the case of the Bi-Sn solder bump on
the Au (0.1 μm)/Ni/Ti UBM, and it was confirmed to be the (Au1−x−yBixNiy)Sn2 phase by XRD. The intermetallic compounds grown form the Au (0.1 μm)/Ni/Ti UBM interface, and they interrupted the growth
of Bi and Sn phases throughout the solder bump. The ultrasmall eutectic Bi-Sn solder bumps on the Au (0.025 μm)/Ni/Ti UBM
showed similar microstructures to those on the Au/Cu/Ti UBM. 相似文献
2.
Investigation of interfacial reaction between Sn-Ag eutectic solder and Au/Ni/Cu/Ti thin film metallization 总被引:3,自引:0,他引:3
J. Y. Park C. W. Yang J. S. Ha C. -U. Kim E. J. Kwon S. B. Jung C. S. Kang 《Journal of Electronic Materials》2001,30(9):1165-1170
This paper reports the formation of intermetallic compounds in Au/Ni/Cu/Ti under-bump-metallization (UBM) structure reacted with Ag-Sn eutectic solder. In this study, UBM is prepared by evaporating Au(500 Å)/Ni(1000 Å)/Cu(7500 Å) /Ti (700 Å) thin films on top of Si substrates. It is then reacted with Ag-Sn eutectic solder at 260 C for various times to induce different stages of the interfacial reaction. Microstructural examination of the interface, using both chemical and crystallographic analysis, indicates that two types of intermetallic compounds are formed during the interfacial reaction. The first phase, formed at the intial stage of the reaction, is predominantly Ni3Sn4. At longer times the Ni3Sn4 phase transforms into (Cu, Ni)6Sn6, probably induced by interdiffusion of Cu and Ni. At this stage, the underlying Cu layer also reacts with Sn and forms the same phase, (Cu,Ni)6Sn5. As a result, the fully reacted interface is found to consist of two intermetallic layers with the same phase but different morphologies. 相似文献
3.
The eutectic Sn-Ag solder alloy is one of the candidates for the Pb-free solder, and Sn-Pb solder alloys are still widely
used in today’s electronic packages. In this tudy, the interfacial reaction in the eutectic Sn-Ag and Sn-Pb solder joints
was investigated with an assembly of a solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. In the Sn-3.5Ag solder joints reflowed at 260°C, only the (Ni1−x,Cux)3Sn4 intermetallic compound (IMC) formed at the solder/Ni interface. For the Sn-37Pb solder reflowed at 225°C for one to ten cycles,
only the (Ni1−x,Cux)3Sn4 IMC formed between the solder and the Ni/Cu under-bump metallization (UBM). Nevertheless, the (Cu1−y,Niy)6Sn5 IMC was observed in joints reflowed at 245°C after five cycles and at 265°C after three cycles. With the aid of microstructure
evolution, quantitative analysis, and elemental distribution between the solder and Ni/Cu UBM, it was revealed that Cu content
in the solder near the solder/IMC interface played an important role in the formation of the (Cu1−y,Niy)6Sn5 IMC. In addition, the diffusion behavior of Cu in eutectic Sn-Ag and Sn-Pb solders with the Ni/Cu UBM were probed and discussed.
The atomic flux of Cu diffused through Ni was evaluated by detailed quantitative analysis in an electron probe microanalyzer
(EPMA). During reflow, the atomic flux of Cu was on the order of 1016−1017 atoms/cm2sec in both the eutectic Sn-Ag and Sn-Pb systems. 相似文献
4.
Mechanism of interfacial reaction for the Sn-Pb solder bump with Ni/Cu under-bump metallization in flip-chip technology 总被引:1,自引:0,他引:1
Guh-Yaw Jang Chien-Sheng Huang Li-Yin Hsiao Jenq-Gong Duh Hideyuki Takahashi 《Journal of Electronic Materials》2004,33(10):1118-1129
Nickel-based under-bump metallization (UBM) has been widely used in flip-chip technology (FCT) because of its slow reaction
rate with Sn. In this study, solder joints after reflows were employed to investigate the mechanism of interfacial reaction
between the Ni/Cu UBM and eutectic Sn-Pb solder. After deliberate quantitative analysis with an electron probe microanalyzer
(EPMA), the effect of Cu content in solders near the interface of the solder/intermetallic compound (IMC) on the interfacial
reaction could be probed. After one reflow, only one layered (Ni1−x,Cux)3Sn4 with homogeneous composition was found between the solder bump and UBM. However, after multiple reflows, another type of
IMC, (Cu1−y,Niy)6Sn5, formed between the solder and (Ni1−x,Cux)3Sn4. It was observed that if the concentration of Cu in the solders near the solder/IMC interface was higher than 0.6 wt.%, the
(Ni1−x,Cux)3Sn4 IMC would transform into the (Cu1−y,Niy)6Sn5 IMC. The Cu contents in (Ni1−x,Cux)3Sn4 were altered and not uniformly distributed anymore. With the aid of microstructure evolution, quantitative analysis, elemental
distribution by x-ray color mapping, and related phase equilibrium of Sn-Ni-Cu, the reaction mechanism of interfacial phase
transformation between the Sn-Pb solder and Ni/Cu UBM was proposed. 相似文献
5.
Intermetallic compound formation and morphology evolution in the 95Pb5Sn flip-chip solder joint with the Ti/Cu/Ni under bump
metallization (UBM) during 350°C reflow for durations ranging from 50 sec to 1440 min were investigated. A thin intermetallic
layer of only 0.4 μm thickness was formed at the 95Pb5Sn/UBM interface after reflow for 5 min. When the reflow was extended
to 20 min, the intermetallic layer grew thicker and the phase identification revealed the intermetallic layer comprised two
phases, (Ni,Cu)3Sn2 and (Ni,Cu)3Sn4. The detection of the Cu content in the intermetallic compounds indicated that the Cu atoms had diffused through the Ni layer
and took part in the intermetallic compound formation. With increasing reflow time, the (Ni,Cu)3Sn4 phase grew at a faster rate than that of the (Ni,Cu)3Sn2 phase. Meanwhile, irregular growth of the (Ni,Cu)3Sn4 phase was observed and voids formed at the (Ni,Cu)3Sn2/Ni interface. After reflow for 60 min, the (Ni,Cu)3Sn2 phase disappeared and the (Ni,Cu)3Sn4 phase spalled off the NI layer in the form of a continuous layer. The gap between the (Ni,Cu)3Sn4 layer and the Ni layer was filled with lead. A possible mechanism for the growth, disappearance, and spalling of the intermetallic
compounds at the 95Pb5Sn/UBM interface was proposed. 相似文献
6.
Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between
the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to
evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in
solder joints. During reflow, the atomic flux of Cu was on the order of 1015–1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion
behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization
was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface
on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%. 相似文献
7.
Electroless Ni-P under bump metallization (UBM) has been widely used in electronic interconnections due to the good diffusion
barrier between Cu and solder. In this study, the mechanical alloying (MA) process was applied to produce the SnAgCu lead-free
solder pastes. Solder joints after annealing at 240°C for 15 min were employed to investigate the evolution of interfacial
reaction between electroless Ni-P/Cu UBM and SnAgCu solder with various Cu concentrations ranging from 0.2 to 1.0 wt.%. After
detailed quantitative analysis with an electron probe microanalyzer, the effect of Cu content on the formation of intermetallic
compounds (IMCs) at SnAgCu solder/electroless Ni-P interface was evaluated. When the Cu concentration in the solder was 0.2
wt.%, only one (Ni, Cu)3Sn4 layer was observed at the solder/electroless Ni-P interface. As the Cu content increased to 0.5 wt.%, (Cu, Ni)6Sn5 formed along with (Ni, Cu)3Sn4. However, only one (Cu, Ni)6Sn5 layer was revealed, if the Cu content was up to 1 wt.%. With the aid of microstructure evolution, quantitative analysis,
and elemental distribution by x-ray color mapping, the presence of the Ni-Sn-P phase and P-rich layer was evidenced. 相似文献
8.
Nickel plating has been used as the under bump metallization (UBM) in the microelectronics industry. The electroplated Ni-P
UBM with different phosphorous contents (7 wt.%, 10 wt.%, and 13 wt.%) was used to evaluate the interfacial reaction between
Ni-P UBM and Sn-3Ag-0.5Cu solder paste during multiple reflow. (Cu,Ni)6Sn5 intermetallic compounds (IMC) formed in the SnAgCu solder/Ni-P UBM interface after the first reflow. For three times reflow,
(Ni,Cu)3Sn4 IMC formed, while (Cu,Ni)6Sn5 IMC spalled into the solder matrix. With further increasing cycles of reflow, the Ni-Sn-P layer formed between (Ni,Cu)3Sn4 IMC and Ni-P UBM for Ni-10wt.%P and Ni-13wt.%P UBM. However, almost no Ni-Sn-P layer was revealed for the Ni-7wt.%P UBM even
after ten cycles of reflow. In consideration of the wettability of Ni-P UBM, the interfacial reaction of SnAgCu/Ni-P, and
dissolution of Ni-P UBM, the optimal phosphorous selection in Ni-P UBM was proposed and also discussed. 相似文献
9.
Flip-chip technology with the layout of ball grid array has been widely used in today’s microelectronics industry. The elemental
distribution in the edge of the solder bump is crucial for its correlation with the bump strength. In this study, Ni/Cu under-bump
metallization (UBM) was used to evaluate the intermetallic compound (IMC) formation in the edge of the solder bump between
the UBM and eutectic Sn-Pb solder in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. During reflows, layered-type (Ni1−xCux)3Sn4 and island-like (Cu1−yNiy)6Sn5 IMCs formed in the interface between the solder and UMB, while only the (Cu1−yNiy)6Sn5 IMC was observed in the sideway of the Ni/Cu UBM. After high-temperature storage (HTS) at 150°C for 1,000 h, both (Cu1−yNiy)6Sn5 and (Cu1−zNiz)3Sn were found in the sideway of the Ni/Cu UBM. Two other IMCs, (Ni1−xCux)3Sn4 and (Cu1−yNiy)6Sn5, formed in the interface between the solder and UBM. The growth of the (Cu1−yNiy)6Sn5 IMC was relatively fast during HTS. 相似文献
10.
Chien-Sheng Huang Jenq-Gong Duh Yen-Ming Chen Jyh-Hwa Wang 《Journal of Electronic Materials》2003,32(2):89-94
Flip-chip interconnection technology plays a key role in today’s electronics packaging. Understanding the interfacial reactions
between the solder and under-bump metallization (UBM) is, thus, essential. In this study, different thicknesses of electroplated
Ni were used to evaluate the phase transformation between Ni/Cu under-bump metallurgy and eutectic Sn-Pb solder in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure for the flip-chip technology. Interfacial reaction products varied with reflow times. After the first
reflow, layered (Ni1−x,Cux)3Sn4 was found between solder and Ni. However, there were two interfacial reaction products formed between solders and the UBM
after three or more times reflow. The layered (Ni1−x,Cux)3Sn4 was next to the Ni/Cu UBM. The islandlike (Cu1−y,Niy)6Sn5 intermetallic compound (IMC) could be related to the Ni thickness and reflow times. In addition, the influence of Cu contents
on phase transformation during reflow was also studied. 相似文献
11.
Chien-Sheng Huang Jenq-Gong Duh Yen-Ming Chen 《Journal of Electronic Materials》2003,32(12):1509-1514
Several international legislations recently banned the use of Pb because of environmental concerns. The eutectic Sn-Ag solder
is one of the promising candidates to replace the conventional Sn-Pb solder primarily because of its excellent mechanical
properties. In this study, interfacial reaction of the eutectic Sn-Ag and Sn-Pb solders with Ni/Cu under-bump metallization
(UBM) was investigated with a joint assembly of solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. After reflows, only one (Ni,Cu)3Sn4 intermetallic compound (IMC) with faceted and particlelike grain feature was found between the solder and Ni. The thickness
and grain size of the IMC increased with reflow times. Another (Cu,Ni)6Sn5 IMC with a rod-type grain formed on (Ni,Cu)3Sn4 in the interface between the Sn-Pb solder and the Ni/Cu UBM after more than three reflow times. The thickness of the (Ni,Cu)3Sn4 layer formed in the Sn-Pb system remained almost identical despite the numbers of reflow; however, the amounts of (Cu,Ni)6Sn5 IMC increased with reflow times. Correlations between the IMC morphologies, Cu diffusion behavior, and IMC transformation
in these two solder systems will be investigated with respect to the microstructural evolution between the solders and the
Ni/Cu UBM. The morphologies and grain-size distributions of the (Ni,Cu)3Sn4 IMC formed in the initial stage of reflow are crucial for the subsequent phase transformation of the other IMC. 相似文献
12.
The effects of various elements of substrate metallization, namely, Au, Ni, and P, on the solder/under-bump metallization
(UBM), (Al/Ni(V)/Cu) interfacial reactions in flip-chip packages during multiple reflow processes were systematically investigated.
It was found that Au and P had negligible effects on the liquid-solid interfacial reactions. However, Ni in the substrate
metallization greatly accelerated the interfacial reactions at chip side and degraded the thermal stability of the UBM through
formation of a (Cu,Ni)6Sn5 ternary compound at the solder/UBM interface. This phenomenon can be explained in terms of enhanced grain-boundary grooving
on (Cu,Ni)6Sn5 in the molten solder during the reflow process. This could eventually cause the rapid spalling of an intermetallic compound
(IMC) from the solder/UBM interface and early failure of the packages. Our results showed that formation of multicomponent
intermetallics, such as (Cu,Ni)6Sn5 or (Ni,Cu)3Sn4, at the solder/UBM interface is detrimental to the solder-joint reliability. 相似文献
13.
High strain-rate drop impact tests were performed on ball grid array (BGA) packages with lead-free Sn-3.8Ag-0.7Cu solder (in
wt.%). Plated Ni and Cu under-bump metallurgies (UBMs) were used on the device side, and their drop test performances were
compared. Failure occurred at the device side, exhibiting brittle interfacial fracture. For Ni UBM, failure occurred along
the Ni/(Cu,Ni)6Sn5 interface, while the Cu UBM case showed failure along the interface between two intermetallics, Cu6Sn5/Cu3Sn. However, the damage across the package varied. For Cu UBM, only a few solder balls failed at the device edge, whereas
on Ni UBM, many more solder bumps failed. The difference in the failure behavior is due to the adhesion of the UBM and intermetallics
rather than the intermetallic thickness. The better adhesion of Cu UBM is due to a more active soldering reaction than Ni,
leading to stronger chemical bonding between intermetallics and UBM. In our reflow condition, the soldering reaction rate
was about 4 times faster on Cu UBM than on Ni UBM. 相似文献
14.
Sang-Su Ha Jong-Woong Kim Jin-Ho Joo Seung-Boo Jung 《Microelectronic Engineering》2007,84(11):2640-2645
This study was focused on the formation and reliability evaluation of solder joints with different diameters and pitches for flip chip applications. We investigated the interfacial reaction and shear strength between two different solders (Sn-37Pb and Sn-3.0Ag-0.5Cu, in wt.%) and ENIG (Electroless Nickel Immersion Gold) UBM (Under Bump Metallurgy) during multiple reflow. Firstly, we formed the flip chip solder bumps on the Ti/Cu/ENIG metallized Si wafer using a stencil printing method. After reflow, the average solder bump diameters were about 130, 160 and 190 μm, respectively. After multiple reflows, Ni3Sn4 intermetallic compound (IMC) layer formed at the Sn-37Pb solder/ENIG UBM interface. On the other hand, in the case of Sn-3.0Ag-0.5Cu solder, (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4 IMCs were formed at the interface. The shear force of the Pb-free Sn-3.0Ag-0.5Cu flip chip solder bump was higher than that of the conventional Sn-37Pb flip chip solder bump. 相似文献
15.
Ti/Ni(V)/Cu underbump metallization (UBM) is widely used in flip-chip technology today. The advantages of Ti/Ni(V)/Cu UBM
are a low reaction rate with solder and the lack of a magnetic effect during sputtering. Sn atoms diffuse into the Ni(V) layer
to form a Sn-rich phase, the so-called Sn-patch, during reflow and aging. In this study, the relationship between interfacial
reaction and mechanical properties of the solder joints with Ti/Ni(V)/Cu UBM was evaluated. Sn-3.0Ag-0.5Cu solder was reflowed
on sputtered Ti/Ni(V)/Cu UBM, and then the reflowed samples were aged at 125°C and 200°C, respectively. (Cu,Ni)6Sn5 was formed and grew gradually at the interface of the solder joints during aging at 125°C. The Sn-patch replaced the Ni(V)
layer, and (Ni,Cu)3Sn4 was thus formed between (Cu,Ni)6Sn5 and the Sn-patch at 200°C. The Sn-patch, composed of Ni and V2Sn3 after reflow, was transformed to V2Sn3 and amorphous Sn during aging. Shear and pull tests were applied to evaluate the solder joints under various heat treatments.
The shear force of the solder joints remained at 421 mN, yet the pull force decreased after aging at 125°C. Both the shear
and pull forces of the solder joints decreased during aging at 200°C. The effects of aging temperature on the mechanical properties
of solder joint were investigated and discussed. 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.
Electromigration-Induced Interfacial Reactions in Cu/Sn/Electroless Ni-P Solder Interconnects 总被引:1,自引:0,他引:1
The effect of electromigration (EM) on the interfacial reaction in a line-type Cu/Sn/Ni-P/Al/Ni-P/Sn/Cu interconnect was investigated
at 150°C under 5.0 × 103 A/cm2. When Cu atoms were under downwind diffusion, EM enhanced the cross-solder diffusion of Cu atoms to the opposite Ni-P/Sn
(anode) interface compared with the aging case, resulting in the transformation of interfacial intermetallic compound (IMC)
from Ni3Sn4 into (Cu,Ni)6Sn5. However, at the Sn/Cu (cathode) interface, the interfacial IMCs remained as Cu6Sn5 (containing less than 0.2 wt.% Ni) and Cu3Sn. When Ni atoms were under downwind diffusion, only a very small quantity of Ni atoms diffused to the opposite Cu/Sn (anode)
interface and the interfacial IMCs remained as Cu6Sn5 (containing less than 0.6 wt.% Ni) and Cu3Sn. EM significantly accelerated the dissolution of Ni atoms from the Ni-P and the interfacial Ni3Sn4 compared with the aging case, resulting in fast growth of Ni3P and Ni2SnP, disappearance of interfacial Ni3Sn4, and congregation of large (Ni,Cu)3Sn4 particles in the Sn solder matrix. The growth kinetics of Ni3P and Ni2SnP were significantly accelerated after the interfacial Ni3Sn4 IMC completely dissolved into the solder, but still followed the t
1/2 law. 相似文献
18.
The Cu pillar is a thick underbump metallurgy (UBM) structure developed to alleviate current crowding in a flip-chip solder
joint under operating conditions. We present in this work an examination of the electromigration reliability and morphologies
of Cu pillar flip-chip solder joints formed by joining Ti/Cu/Ni UBM with largely elongated ∼62 μm Cu onto Cu substrate pad metallization using the Sn-3Ag-0.5Cu solder alloy. Three test conditions that controlled average
current densities in solder joints and ambient temperatures were considered: 10 kA/cm2 at 150°C, 10 kA/cm2 at 160°C, and 15 kA/cm2 at 125°C. Electromigration reliability of this particular solder joint turns out to be greatly enhanced compared to a conventional
solder joint with a thin-film-stack UBM. Cross-sectional examinations of solder joints upon failure indicate that cracks formed
in (Cu,Ni)6Sn5 or Cu6Sn5 intermetallic compounds (IMCs) near the cathode side of the solder joint. Moreover, the ~52-μm-thick Sn-Ag-Cu solder after long-term current stressing has turned into a combination of ~80% Cu-Ni-Sn IMC and ~20% Sn-rich
phases, which appeared in the form of large aggregates that in general were distributed on the cathode side of the solder
joint. 相似文献
19.
The interfacial reaction between Ni and Sn-3Ag-0.5Cu-xPd alloys (x = 0 wt.% to 1 wt.%) at 250°C and the mechanical reliability of the solder joints were investigated in this study. The reaction
and the resulting mechanical properties were both strongly dependent on the Pd concentration. When x was low (≤0.2 wt.%), the reaction product at the Ni/Sn-Ag-Cu-xPd interface was a layer of (Cu,Ni)6Sn5. An increase of x to 0.3 wt.% produced one additional (Pd,Ni)Sn4 compound that was discontinuously scattered above the (Cu,Ni)6Sn5. When x was relatively high (0.5 wt.% to 1 wt.%), a dual layer of (Pd,Ni)Sn4-(Cu,Ni)6Sn5 developed with the reaction time. The results of the high-speed ball shear (HSBS) test showed that the mechanical strength
of the Ni/Sn-3Ag-0.5Cu-xPd joints degraded with increasing x, especially when x reached a high level of ≥0.3 wt.%. This degradation corresponded to the growth of (Pd,Ni)Sn4 at the interface, and joints easily failed along the boundaries of solder/(Pd,Ni)Sn4 and (Pd,Ni)Sn4/(Cu,Ni)6Sn5 in the HSBS test. The (Pd,Ni)Sn4-induced joint failure (Pd embrittlement) was alleviated by doping the solder with an appropriate amount of Cu. When the Cu
concentration increased to 1 wt.% and the Pd concentration did not exceed 0.5 wt.%, the growth of (Pd,Ni)Sn4 could be thoroughly inhibited, thereby avoiding the occurrence of Pd embrittlement in the solder joints. 相似文献
20.
Moon Gi Cho Sung K. Kang Sun-Kyoung Seo Da-Yuan Shih Hyuck Mo Lee 《Journal of Electronic Materials》2009,38(11):2242-2250
The effects of the addition of Zn to Sn-0.7Cu solders are investigated. The study is focused on the interfacial reactions,
microstructures, and mechanical properties after reaction with Ni-P under bump metallurgies (UBMs). The Zn contents in Sn-0.7Cu-xZn are varied as 0.2, 0.4, and 0.8 (in wt.% unless otherwise specified). In the reaction with Ni-P UBM during thermal aging
at 150°C for 1000 h, (Cu,Ni)6Sn5 intermetallic compounds (IMCs) are formed at the Sn-0.7Cu/UBM interface, whereas Zn is incorporated into IMCs to form (Cu,Ni,Zn)6Sn5 in the Zn-doped solders. As the Zn content increases, the interfacial IMC thickness is reduced. A total reduction of about
40% in IMC thickness was observed for the 0.8% Zn-doped Sn-Cu. The same IMC particles are also observed in the matrix of each
solder. In Sn-0.7Cu, (Cu,Ni)6Sn5 particles are coarsened during aging, while (Cu,Ni,Zn)6Sn5 particles in the Zn-added solders are less coarsened and remain much smaller than (Cu,Ni)6Sn5. The growth rate of (Cu,Ni)6Sn5 during thermal aging is significantly suppressed by the addition of Zn. Consequently, after reaction with Ni-P UBM, the Zn-doped
solders exhibit a thermally stable microstructure as measured by hardness and shear strength. 相似文献