共查询到20条相似文献,搜索用时 203 毫秒
1.
Young-Doo Jeon Kyung-Wook Paik Adreas Ostmann Herbert Reichl 《Journal of Electronic Materials》2005,34(1):80-90
Using the screen-printed solder-bumping technique on the electroless plated Ni-P under-bump metallurgy (UBM) is potentially
a good method because of cost effectiveness. As SnAgCu Pb-free solders become popular, demands for understanding of interfacial
reactions between electroless Ni-P UBMs and Cu-containing Pb-free solder bumps are increasing. It was found that typical Ni-Sn
reactions between the electroless Ni-P UBM and Sn-based solders were substantially changed by adding small amounts of Cu in
Sn-based Pb-free solder alloys. In Cu-containing solder bumps, the (Cu,Ni)6Sn5 phase formed during initial reflow, followed by (Ni,Cu)3Sn4 phase formation during further reflow and aging. The Sn3.5Ag solder bumps showed a much faster electroless Ni-P UBM consumption
rate than Cu-containing solder bumps: Sn4.0Ag0.5Cu and Sn0.7Cu. The initial formation of the (Cu,Ni)6Sn5 phase in SnAgCu and SnCu solders significantly reduced the consumption of the Ni-P UBM. The more Cu-containing solder showed
slower consumption rate of the Ni-P UBM than the less Cu-containing solder below 300°C heat treatments. The growth rate of
the (Cu,Ni)6Sn5 intermetallic compound (IMC) should be determined by substitution of Ni atoms into the Cu sublattice in the solid (Cu,Ni)6Sn5 IMC. The Cu contents in solder alloys only affected the total amount of the (Cu,Ni)6Sn5 IMC. More Cu-containing solders were recommended to reduce consumption of the Ni-based UBM. In addition, bump shear strength
and failure analysis were performed using bump shear test. 相似文献
2.
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
3.
This work summarizes the interfacial reaction between lead-free solder Sn-3.5Ag and electrolessly plated Ni-P metallization
in terms of morphology and growth kinetics of the intermetallic compounds (IMC). Comparison with pure Ni metallization is
made in order to clarify the role of P in the solder reaction. During reflow, the IMCs formed with the Ni-P under-bump metallization
(UBM) exist in chunky crystal blocks and small crystal agglomerates, while the ones with the sputtered Ni UBM exhibit uniformly
scallop grains with faceted surfaces. The IMC thickness increases with reflow time following approximately a t1/3 power law for both systems. The IMC growth rate is higher with the Ni-P UBM than the Ni UBM. The thickness of the Ni3Sn4 layer increases linearly with the square root of thermal aging time, indicating that the growth of the IMCs is a diffusion-controlled
process. The activation energy for Ni3Sn4 growth in solid-state reaction is found to be 110 kJ/mol and 91 kJ/mol for the Ni-P and sputtered Ni UBMs, respectively.
Kirkendall voids are detected inside the Ni3P layer in the Sn-3.5Ag/Ni-P system. No such voids are found in the Sn-3.5Ag/Ni system. 相似文献
4.
Young-Doo Jeon Sabine Nieland Andreas Ostmann Herbert Reichl Kyung-Wook Paik 《Journal of Electronic Materials》2003,32(6):548-557
Even though electroless Ni-P and Sn-Ag-Cu solders are widely used materials in flip-chip bumping technologies, interfacial
reactions of the ternary Cu-Ni-Sn system are not well understood. The growth of intermetallic compounds (IMCs) at the under
bump metallization (UBM)/solder interface can affect solder-joint reliability, so analysis of IMC phases and understanding
their growth kinetics are important. In this study, interfacial reactions between electroless Ni-P UBM and the 95.5Sn-4.0Ag-0.5Cu
alloy were investigated, focusing on identification of IMC phases and IMC growth kinetics at various reflowing and aging temperatures
and times. The stable ternary IMC initially formed at the interface after reflowing was the (Cu,Ni)6Sn5 phase. However, during aging, the (Cu,Ni)6Sn5 phase slowly changed into the quaternary IMC composed of Cu, Ni, Sn, and a small amount of Au. The Au atoms in the quaternary
IMC originated from immersion Au plated on electroless Ni-P UBM. During further reflowing or aging, the (Ni,Cu)3Sn4 IMC started forming because of the limited Cu content in the solder. Morphology, composition, and crystal structure of each
IMC were identified using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Small amounts of
Cu in the solder affect the types of IMC phases and the amount of the IMC. The activation energies of (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4 IMCs were used to estimate the growth kinetics of IMCs. The growth of IMCs formed in aging was very slow and temperature-dependent
compared to IMCs formed in reflow because of the higher activation energies of IMCs in aging. Comparing activation energies
of each IMC, growth mechanism of IMCs at electroless Ni-P/SnAgCu solder interface will be discussed. 相似文献
5.
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
6.
The interfacial reactions and shear properties of In-48wt.%Sn/Au/Ni/Cu solder joints were investigated in terms of reflow
conditions, i.e., reflow temperature and duration time. The thickness of an AuIn2 intermetallic compound (IMC) layer, formed at the solder/substrate interface, slightly increased with the duration time.
The spalling of the AuIn2 intermetallics in the solder led to the formation of a Ni3(Sn,In)4 IMC layer between the solder and exposed Ni layer. The longer duration time resulted in the spalling and grain growth of
Ni3(Sn,In)4 intermetallics. The higher reflow temperature accelerated the interfacial reactions between the solder and substrate. From
the ball shear test results, the formation and growth of a continuous plate-shaped AuIn2 IMC layer increased the shear force of the solder joints, whereas the spalling and grain growth of cubic-shaped AuIn2 intermetallics significantly decreased the shear force. The formation and spalling of cubic-shaped Ni3(Sn,In)4 intermetallics increased the shear force, whereas the spalling and grain growth of polyhedron-shaped Ni3(Sn,In)4 intermetallics decreased the shear force. The crack propagated at the Au-rich/AuIn2/solder interface in the initial reflow stage, then toward the AuIn2 intermetallics dispersed in the solder matrix, and finally along the Ni3(Sn,In)4 intermetallics spalling off in the solder. 相似文献
7.
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
8.
Electroless Ni-P layers with three different P contents (6.1 wt.%, 8.8 wt.%, and 12.3wt.%) were deposited on copper (Cu) substrates.
Multilayered samples of Sn-3.5Ag/Ni-P/Cu stack were prepared and subjected to multiple reflows at 250°C. A tensile test was
performed to investigate the effect of P content on the solder joint strength. The low P samples exhibited the highest joint
strength after multiple reflows, while the strength of medium and high P samples decreased more rapidly. From interfacial
analysis, the Ni3Sn4 intermetallic compound (IMC) formed at the interface of low P sample was found to be more stable, while the one of medium
and high P samples spalled into the molten solder. The IMC spallation sped up the consumption of electroless Ni-P, leading
to the large formation of Cu-Sn IMCs. Fractographic and microstructural analyses showed that the degradation in solder joint
strength was due to the formation of layers of voids and growth of Cu-Sn IMCs between the solder and the Cu substrate. 相似文献
9.
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
10.
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
11.
Effects of Co Addition on Bulk Properties of Sn-3.5Ag Solder and Interfacial Reactions with Ni-P UBM
Dong Hoon Kim Moon Gi Cho Sun-Kyoung Seo Hyuck Mo Lee 《Journal of Electronic Materials》2009,38(1):39-45
The effects of Co addition on the undercooling, microstructure, and microhardness of Sn-3.5Ag solder (all in wt.% unless specified
otherwise) and interfacial reactions with Ni-P under bump metallurgy (UBM) are investigated when the Co content varies from
0.01 wt.% to 0.7 wt.%. When more than 0.02 wt.% Co was added to Sn-3.5Ag solder, the undercooling of the Sn-3.5Ag solder
was significantly reduced and the microstructures coarsened with the increased eutectic region. In addition, the hardness
value increased as the Co content in Sn-3.5Ag increased. In the interfacial reactions with Ni-P UBM, a spalling phenomenon
of intermetallic compounds (IMCs) during reflow was prevented in the Sn-3.5Ag-xCo (x ≥ 0.02 wt.%). However, when more than 0.05 wt.% Co was added to Sn-3.5Ag, the IMC morphology changed from a bulky shape to
a plate-like shape. The bulky IMCs were Ni3Sn4 and the plate-like IMCs were Sn-Ni-Co ternary compounds. The main issues discussed include the relations between the morphological
changes and the IMC phases, the effects of Co addition on the prevention of IMC spalling, and the optimum level of Co addition. 相似文献
12.
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
13.
Ying Yang J. N. Balaraju Yizhong Huang Yee Yan Tay Yiqiang Shen Zviad Tsakadze Zhong Chen 《Journal of Electronic Materials》2014,43(11):4103-4110
The voids formed in the Ni3P layer during reaction between Sn-based solders and electroless Ni–P metallization is an important cause of rapid degradation of solder joint reliability. In this study, to suppress formation of the Ni3P phase, an electrolessly plated Ni–Sn–P alloy (6–7 wt.% P and 19–21 wt.% Sn) was developed to replace Ni–P. The interfacial microstructure of electroless Ni–Sn–P/Sn–3.5Ag solder joints was investigated after reflow and solid-state aging. For comparison, the interfacial reaction in electroless Ni–P/Sn–3.5Ag solder joints under the same reflow and aging conditions was studied. It was found that the Ni–Sn–P metallization is consumed much more slowly than the Ni–P metallization during soldering. After prolonged reaction, no Ni3P or voids are observed under SEM at the Ni–Sn–P/Sn–3.5Ag interface. Two main intermetallic compounds, Ni3Sn4 and Ni13Sn8P3, are formed during the soldering reaction. The reason for Ni3P phase suppression and the overall mechanisms of reaction at the Ni–Sn–P/Sn–3.5Ag interface are discussed. 相似文献
14.
The interfaces between electroless Ni-P deposit and Pb-Sn solder and Sn-Ag solder were formed by reflowing for different time
periods to examine their microstructures and microchemistry. It was found that the Pb-Sn solder interface is more stable than
the Sn-Ag solder interface. Sn-Ag solder reacts quickly with the electroless Ni-P deposit and forms nonadherent Ni-Sn intermetallic
compounds (IMCs). Pb-Sn solder reacts slowly and forms adherent Ni-Sn IMC. A P-rich Ni layer, revealed as a dark layer under
scanning electron microscopy (SEM), is formed on the electroless Ni-P deposit due to the solder reaction. For short reflow
times, this P-rich Ni layer consists of only Ni3P compound, but during prolonged reflow, new crystals of Ni2P, Ni5P4, and NiP2 are also found to be formed from the amorphous electroless Ni-P layer. 相似文献
15.
H. R. Kotadia O. Mokhtari M. Bottrill M. P. Clode M. A. Green S. H. Mannan 《Journal of Electronic Materials》2010,39(12):2720-2731
In this study we consider the effect of separately adding 0.5 wt.% to 1.5 wt.% Zn or 0.5 wt.% to 2 wt.% Al to the eutectic
Sn-3.5Ag lead-free solder alloy to limit intermetallic compound (IMC) growth between a limited volume of solder and the contact
metallization. The resultant solder joint microstructure after reflow and high-temperature storage at 150°C for up to 1000 h
was investigated. Experimental results confirmed that the addition of 1.0 wt.% to 1.5 wt.% Zn leads to the formation of Cu-Zn
on the Cu substrate, followed by massive spalling of the Cu-Zn IMC from the Cu substrate. Growth of the Cu6Sn5 IMC layer is significantly suppressed. The addition of 0.5 wt.% Zn does not result in the formation of a Cu-Zn layer. On
Ni substrates, the Zn segregates to the Ni3Sn4 IMC layer and suppresses its growth. The addition of Al to Sn-3.5Ag solder results in the formation of Al-Cu IMC particles
in the solder matrix when reflowed on the Cu substrate, while on Ni substrates Al-Ni IMCs spall into the solder matrix. The
formation of a continuous barrier layer in the presence of Al and Zn, as reported when using solder baths, is not observed
because of the limited solder volumes used, which are more typical of reflow soldering. 相似文献
16.
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
17.
Electroless Ni-P/Cu under-bump metallization (UBM) is widely used in electronics packaging. The Sn3.0Ag0.5Cu lead-free composite
solder pastes were produced by a mechanical alloying (MA) process doped with Cu6Sn5 nanoparticles. In this study, the detailed interfacial reaction of Sn3.0Ag0.5Cu composite solders with EN(P)/Cu UBM was investigated
after reflow. A field-emission scanning electron microscope (FESEM) was employed to analyze the interfacial morphology and
microstructure evolution. The intermetallic compounds (IMCs) formed at the interface between the Sn3.0Ag0.5Cu composite solders
and EN(P)/Cu UBM after one and three reflows were mainly (Ni1−x,Cux)3Sn4 and (Cu1−y,Niy)6Sn5. However, only (Ni1−x,Cux)3Sn4 IMC was observed after five reflows. The elemental distribution near the interfacial region was evaluated by an electron
probe microanalyzer (EPMA) as well as field-emission electron probe microanalyzer (FE-EPMA). Based on the observation and
characterization by FESEM, a EPMA, and an FE-EPMA, the reaction mechanism of interfacial phase transformation between Sn3.0Ag0.5Cu
composite solders and EN(P)/Cu UBM after various reflow cycles was discussed and proposed. 相似文献
18.
The interfacial microstructure of electroless Ni-P/Sn-3.5Ag solder joints was investigated after reflow and high-temperature
solid-state aging to understand its interdependent growth mechanism and related kinetics of intermetallic compounds (IMCs)
at the interface. The reflow and aging results showed that mainly three IMC layers, Ni3Sn4, Ni2SnP, and Ni3P, formed during the soldering reaction. It was found that the Ni3Sn4 and Ni3P layers grow predominantly as long as the electroless Ni-P layer is present; however, once the Ni-P layer is fully consumed,
the Ni2SnP layer grows rapidly at the expense of the Ni3P layer. A transition in the Ni3Sn4 morphology from needle and chunky shape to scallop shape was observed after the solid-state aging of reflowed samples. The
kinetics data obtained from the growth of compound layers in the aged samples revealed that initially the growth of the Ni2SnP layer is controlled by diffusion, and subsequently by the rate of reaction after the Ni-P metallization is fully consumed.
It was found that complete transformation of the electroless Ni-P layer into a Ni3P layer results in the rapid growth of the Ni2SnP layer due to the dominating reaction of Sn with Ni3P. The apparent activation energies for the growth of Ni3Sn4, Ni2SnP, and Ni3P compound layers were found to be 98.9 kJ/mol, 42.2 kJ/mol, and 94.3 kJ/mol, respectively. 相似文献
19.
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
20.
Young-Doo Jeon Kyung-Wook Paik Kyung-Soon Bok Woo-Suk Choi Chul-Lae Cho 《Journal of Electronic Materials》2002,31(5):520-528
The electroless-deposited Ni-P under bump metallurgy (UBM) layer was fabricated on Al pads for Sn containing solder bumps. The amount of P in the electroless Ni film was optimized by controlling complexing agents and the pH of plating solution. The interfacial reaction at the electroless Ni UBM/solder interface was investigated in this study. The intermetallic compound (IMC) formed at the interface during solder reflowing was mainly Ni3Sn4, and a P-rich Ni layer was also formed as a by-product of Ni-Sn reaction between the Ni-Sn IMC and the electroless Ni layer. One to four microns of Ni3Sn4 IMC and a 1800–5000 Å of P-rich Ni layer were formed in less than 10 min of solder reflowing depending on solder materials and reflow temperatures. It was found that the P-rich Ni layer contains Ni, P, and a small amount of Sn (~7 at.%). Further cross-sectional transmission electron microscopy (TEM) analysis confirmed that the composition of the P-rich Ni layer was 75 at.% Ni, 20at.%P, and 5at.%Sn by energy-dispersive x-ray spectroscopy (EDS) and the phase transformation occurred in the P-rich Ni layer by observing grain size. Kirkendall voids were also found in the Ni3Sn4 IMC, just above the P-rich Ni layer after extensive solder reflow. The Kirkendall voids are considered a primary cause of the brittle fracture; restriction of the growth of of the P-rich Ni layer by optimizing proper processing conditions is recommended. The growth kinetics of Ni-Sn IMC and P-rich Ni layer follows three steps: a rapid initial growth during the first 1 min of solder reflow, followed by a reduced growth step, and finally a diffusion-controlled growth. During the diffusion-controlled growth, there was a linear dependence between the layer thickness and time1/2. Flip chip bump shear testing was performed to measure the effects of the IMC and the P-rich Ni layers on bump adhesion property. Most failures occurred in the solder and at the Ni3Sn4 IMC. The brittle characteristics of the Ni-Sn IMC and the Kirkendall voids at the electroless Ni UBM-Sn containing solder system cause brittle bump failure, which results in a decreased bump adhesion strength. 相似文献