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1.
2.
Interfacial reactions between Bi-Ag high-temperature solders and metallic substrates 总被引:3,自引:0,他引:3
This study investigated the interfacial morphology and tensile properties of the joints between Bi-Ag solders and two metallic
substrates, Cu and Ni. Instead of forming intermetallic compounds, grooving occurred at the intersections of Cu grain boundaries
with the Bi-Ag/Cu interface and thus provided mechanical bonding. As for the Ni substrate, cellular NiBi3 was observed at the interface and also, massive NiBi3 in the form of long blades emanating from the interface was located within the solder region. A thin NiBi layer formed through
a solid-state reaction between NiBi3 and the solder. The formation of those Ni-Bi intermetallics had a strong influence on the tensile strength and fracture morphology
of the Bi-Ag/Ni joints. 相似文献
3.
Effects of Trace Amounts of Rare Earth Additions on Microstructure and Properties of Sn-Bi-Based Solder Alloy 总被引:3,自引:0,他引:3
Wenxing Dong Yaowu Shi Zhidong Xia Yongping Lei Fu Guo 《Journal of Electronic Materials》2008,37(7):982-991
The effect of trace amounts of rare earth additions on the microstructure and properties were studied for the Sn-58Bi and
Sn-58Bi-Ag solder alloys. At the same time, the intermetallic compounds (IMCs) in the solder alloys and intermetallic layer
(IML) thickness at the solder/Cu substrate interface were investigated, both as-reflowed and after high-temperature aging.
The results indicate that adding trace amounts of rare earth (RE) elements has little influence on the melting temperature
and microhardness of the solders investigated, but adding RE elements improves the wettability and shear strength of the Sn-58Bi
and Sn-58Bi-Ag solder alloys. In addition, it was found that the addition of RE elements not only refines the microstructure
and size of the IMC particles, but also decreases the IML thickness and shear strength of the Sn-58Bi solder joint after high-temperature
aging. Adding trace amounts of RE elements is superior to adding trace amounts of Ag for improving the properties of the Sn-58Bi
solder. The reason may be related to the modification of the microstructure of the solder alloys due to the addition of trace
amounts of RE elements. 相似文献
4.
Lead-free solders have high Sn content and high melting temperature, which often cause excessive interfacial reactions at the interface. Sn3.5Ag0.5Cu lead-free solder alloy has been used to identify its interfacial reactions with two-metal layer flexible substrates. In this paper we investigate the dissolution kinetics of Sn3.5Ag0.5Cu solder on electrolytic Ni/electroless NiP layer. It is found that during 1 min of reflow electroless NiP layer dissolves slightly lower than the electrolytic Ni due to the barrier layer formation between the intermetallic compounds (IMCs) and electroless NiP layer. Faster nucleation of IMCs on the electrolytic Ni layer is proposed as the main reason for higher initial dissolution. The appearance of P-rich Ni layer acts as a diffusion barrier layer between the solder and electroless NiP layer, which decreases the dissolution rate and IMCs growth rate than that of the electrolytic Ni layer, but weaken the interface and reduces the ball shear strength and reliability. After acquiring certain thickness P-rich Ni layer breaks and increases the diffusion rate of Sn and as a consequence both the IMCs growth rate and dissolution rate also increases. It is found that 3 μm thick electroless NiP layer cannot protect the Cu layer for more than 120 min at 250 °C. In electrolytic Ni shear strength does not change significantly and lower dissolution rate and more protective for Cu layer during long time molten reaction. 相似文献
5.
An improved numerical method for predicting intermetallic layer thickness developed during the formation of solder joints on Cu substrates 总被引:1,自引:0,他引:1
S. Chada W. Laub R. A. Fournelle D. Shangguan 《Journal of Electronic Materials》1999,28(11):1194-1202
An improved numerical method has been developed for calculating the thickness of intermetallic layers formed between Cu substrates
and solders during the soldering process. The improved method takes into account intermetallic dissolution during heating
and intermetallic precipitation during cooling and requires as input (1) the temperature-time profile for the soldering process,
(2) the experimentally determined isothermal growth parameters for the growth of the intermetallic layer into Cu saturated
molten solder, (3) the experimentally determined Nernst-Brunner parameters for the dissolution of Cu into molten solder, (4)
the experimentally determined solubility of Cu in molten solder and (5) assumptions about the thickness of the boundary layer
in the liquid ahead of the growing intermetallic. Calculations show that the improved method predicts intermetallic growth
between Cu substrates and 96.5Sn-3.5Ag solder during reflow soldering better than a previously developed method, which did
not take into account dissolution during heating and precipitation during cooling. Calculations further show that dissolution
has a significant effect on growth, while precipitation does not. 相似文献
6.
Dissolution behavior of Cu and Ag substrates in molten solders 总被引:1,自引:0,他引:1
This study investigated the dissolution behavior of Cu and Ag substrates in molten Sn, Sn-3.5Ag, Sn-4.0Ag-0.5Cu, Sn-8.6Zn
and Sn-8.55Zn-0.5Ag-0.1Al-0.5Ga lead-free solders as well as in Sn-37Pb solder for comparison at 300, 350, and 400°C. Results
show that Sn-Zn alloys have a substantially lower dissolution rate of both Cu and Ag substrates than the other solders. Differences
in interfacial intermetallic compounds formed during reaction and the morphology of these compounds strongly affected the
substrate dissolution behavior. Soldering temperature and the corresponding solubility limit of the substrate elements in
the liquid solder also played important roles in the interfacial morphology and dissolution rate of substrate. 相似文献
7.
In this work, the shear strengths and the interfacial reactions of Sn-9Zn, Sn-8Zn-1Bi, and Sn-8Zn-3Bi (wt.%) solders with
Au/Ni/Cu ball grid array (BGA) pad metallization were systematically investigated after extended reflows. Zn-containing Pb-free
solder alloys were kept in molten condition (240°C) on the Au/electrolytic Ni/Cu bond pads for different time periods ranging
from 1 min. to 60 min. to render the ultimate interfacial reaction and to observe the consecutive shear strength. After the
shear test, fracture surfaces were investigated by scanning electron microscopy equipped with an energy dispersive x-ray spectrometer.
Cross-sectional studies of the interfaces were also conducted to correlate with the fracture surfaces. The solder ball shear
load for all the solders during extended reflow increased with the increase of reflow time up to a certain stage and then
decreased. It was found that the formation of thick Ni-Zn intermetallic compound (IMC) layers at the solder interface of the
Au/electrolytic Ni/Cu bond pad with Sn-Zn(-Bi) alloys deteriorated the mechanical strength of the joints. It was also noticed
that the Ni-Zn IMC layer was larger in the Sn-Zn solder system than that in the other two Bi-containing solder systems. 相似文献
8.
M. Nahavandi M. A. Azmah Hanim Z. N. Ismarrubie A. Hajalilou R. Rohaizuan M. Z. Shahrul Fadzli 《Journal of Electronic Materials》2014,43(2):579-585
Replacing high-temperature leaded solders with lead-free alternatives is an important issue in the electronics industry. This study investigates the viability of lead-free Bi-Ag and Bi-Sb solder alloys, ranging in composition from 1.5 to 5 wt.% Ag and Sb. The effects of melting point, wetting angle, microstructure, and morphology were analysed by differential scanning calorimetry, optical microscopy, and scanning electron microscope–energy dispersive x-ray analysis. The results showed that all tested alloys had suitable melting temperatures, ranging from 271 to 276°C. The wetting angle increased by raising the Sb content, but, in contrast, by increasing the wt.% of Ag, the wetting angle decreased. A Cu-rich phase was present in all Bi-Ag alloys, The Cu-rich phase was also present in decreasing amounts with increasing Sb, but, with 5Sb, there was no Cu-rich phase, and a Cu3Sb intermetallic compound was present in the interface and as precipitates in the solder. Grooving along Cu grain boundaries was observed at the interface for the rest of the alloys. 相似文献
9.
Copper substrate dissolution in eutectic Sn-Ag solder and its effect on microstructure 总被引:3,自引:0,他引:3
S. Chada R. A. Fournelle W. Laub D. Shangguan 《Journal of Electronic Materials》2000,29(10):1214-1221
The dissolution of Cu into molten Sn-3.8at.%Ag (Sn-3.5wt.%Ag) solder and its effect on microstructure were studied by light
microscopy, scanning microscopy, and x-ray microanalysis. X-ray microanalysis of the average Cu content of samples soldered
under various conditions showed that the amount of Cu dissolved during soldering increased with increasing soldering temperature
and time and that the rate of dissolution could be described by a Nernst-Brunner equation. Microstructurally it was found
that the volume fractions of primary β(Sn) dendrites and η-phase dendrites increase with increasing soldering temperature
and time. The microstructural changes can be explained using Sn-Ag-Cu phase equilibrium data. A numerical method was developed
for calculating the amount of Cu dissolved under non-isothermal conditions, which describes dissolution reasonably well. 相似文献
10.
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
11.
Effect of substrate metallization on interfacial reactions and reliability of Sn-Zn-Bi solder joints
Ahmed Sharif 《Microelectronic Engineering》2007,84(2):328-335
The scope of this paper covers a comprehensive study of the lead-free Sn-Zn-Bi solder system, on Cu, electrolytic Ni/Au and electroless Ni(P)/Au surface finishes. This includes a study of the shear properties, intermetallic compounds at the substrate-ball interface and dissolution of the under bump metallization. The Sn-8Zn-3Bi (wt.%) solder/Cu system exhibited a low shear load with thick IMCs formation at the interface. The dissolution of the Cu layer in the Sn-Zn-3Bi solder is higher than that of the other two Ni metallizations. It was found that the formation of a thick Ni-Zn intermetallic compound (IMC) layer at the solder interface of the electrolytic Ni bond pad reduced the mechanical strength of the joints during high temperature long time liquid state annealing. The solder ball shear-load for the Ni(P) system during extended reflow increased with an increase of reflow time. No spalling was noticed at the interface of the Sn-Zn-3Bi solder/Ni(P) system. Sn-8Zn-3Bi solder with electroless Ni(P) metallization appeared as a good combination in soldering technology. 相似文献
12.
The mutual interaction between Sn/Ni and Sn/Cu interfacial reactions in a Ni/Sn/Cu sandwich sample has been studied. The major
interfacial reaction product on the Cu side was Cu6Sn5, while on the Ni side, a ternary (Cu,Ni)6Sn5 compound layer was formed. We found that the growth kinetics of the interfacial compound layers on both sides reached a steady
state in the late reflow stage. The interfacial compound layer on the Cu side retained a constant thickness. On the other
hand, the interfacial compound layer on the Ni side grew at a relatively fast rate, which was found to be linear with time.
Our results indicate that the growth of the ternary (Cu,Ni)6Sn5 compound layer was controlled by the Cu dissolution flux at the solder/Cu6Sn5 compound interface. The dissolution constant of the Cu6Sn5 compound into the molten Sn was determined to be 0.13 μm/s.
Institute of Materials Science and Engineering, National Central University. 相似文献
13.
Ni underbump metallization (UBM) has been widely used as the diffusion barrier between solder and Cu pads. To retard the fast
dissolution rate of Ni UBM, Cu was added into Ni thin films. The Ni-Cu UBM can provide extra Cu to the solders to maintain
the Cu6Sn5 intermetallic compound (IMC) at the interface, which can thus significantly decrease the Ni dissolution rate. In this study,
the Cu content of the sputtered Cu/Ni-xCu/Ti UBM was varied from 0 wt.% to 20 wt.%. Sn-3Ag-0.5Cu solder was reflowed with Cu/Ni-Cu/Ti UBM one, three, and five times.
Reflow and cooling conditions altered the morphology of the IMCs formed at the interface. The amount of (Cu,Ni)6Sn5 increased with increasing Cu content in the Ni-Cu film. The Cu concentration of the intermetallic compound was strongly dependent
on the composition of the Ni-Cu films. The results of this study suggest that Cu-rich Ni-xCu UBM can be used to suppress interfacial spalling and improve shear strength and pull strength of solder joints. 相似文献
14.
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
15.
Jong-Hyun Lee Daejin Park Jong-Tae Moon Yong-Ho Lee Dong-Hyuk Shin Yong-Seog Kim 《Journal of Electronic Materials》2000,29(10):1153-1159
In an attempt to develop a fluxless reflow solder bumping process, the effects of processing variables, which include energy
input rate and time, and the shape of solder disk on the microstructure of the solder/Cu pad interface and the shear strength
of the joints were investigated. It was demonstrated that a proper combination of the variables could lead to the formation
of a spherical solder bump with shear strength comparable to that formed via the conventional reflow soldering process. In
addition, the kinetics of Cu pad dissolution into the solder during laser heating was modeled numerically to elucidate intermetallic
formation mechanism at the solder/Cu pad interface.
Jointly appointed by CAAM at POSTECH 相似文献
16.
Effects of microstructural evolution and intermetallic layer growth on shear strength of ball-grid-array Sn-Cu solder joints 总被引:1,自引:0,他引:1
The shear strength of ball-grid-array (BGA) solder joints on Cu bond pads was studied for Sn-Cu solder containing 0, 1.5,
and 2.5 wt.% Cu, focusing on the effect of the microstructural changes of the bulk solder and the growth of intermetallic
(IMC) layers during soldering at 270°C and aging at 150°C. The Cu additions in Sn solder enhanced both the IMC layer growth
and the solder/IMC interface roughness during soldering but had insignificant effects during aging. Rapid Cu dissolution from
the pad during reflow soldering resulted in a fine dispersion of Cu6Sn5 particles throughout the bulk solder in as-soldered joints even for the case of pure Sn solder, giving rise to a precipitation
hardening of the bulk solder. The increased strength of the bulk solder caused the fracture mode of as-soldered joints to
shift from the bulk solder to the solder/IMC layer as the IMC layer grew over a critical thickness about 1.2 m for all solders.
The bulk solder strength decreased rapidly as the fine Cu6Sn5 precipitates coarsened during aging. As a consequence, regardless of the IMC layer thickness and the Cu content of the solders,
the shear strength of BGA solder joints degraded significantly after 1 day of aging at 150°C and the shear fracture of aged
joints occurred in the bulk solder. This suggests that small additions of Cu in Sn-based solders have an insignificant effect
on the shear strength of BGA solderjoints, especially during system use at high temperatures. 相似文献
17.
The electroless nickel immersion gold (ENIG) process results in surface defects, such as pinholes and black pads, which weaken the solder joint and eventually degrade the reliability of the PCB. Contamination of the plating solutions, including dissolution of the solder resist (SR), can be a cause of the pinholes and black pads. This study examined the effects of SR dissolution on the solder joint reliability and electroless Ni plating properties. Electroless Ni plating was performed by adding 1 to 10 ppm hardener (melamine) to the fresh Ni solution. Many black pads were observed in the 7 and 10 ppm hardener-added surfaces. In addition, the content of P was highest when 7 and 10 ppm hardener was added. The ball shear tests were carried out to confirm the joint reliability between the ENIG surface with hardener-added and the Sn-3.0Ag-0.5Cu solder (SAC 305). The ball shear strength decreased with increasing dissolution of the hardener. In particular, the shear strength was the lowest at 7 and 10 ppm hardener addition. In addition, the failure mode of the solder joint was changed from ductile to brittle mode with increasing hardener addition. That is, as the hardener additive increases, intermetallic compound (IMC) phases were changed from (Cu,Ni)6Sn5 to (Cu,Ni)3Sn4 and Cu6Sn5 (brittle structure). 相似文献
18.
Wetting reactions between eutectic AuSn solder and Au foil have been studied. During the reflow process, Au foil dissolution
occurred at the interface of AuSn/Au, which increases with temperature and time. The activation energy for Au dissolution
in molten AuSn solder is determined to be 41.7 kJ/mol. Au5Sn is the dominant interfacial compound phase formed at the interface. The activation energy for the growth of the interfacial
Au5Sn phase layer is 54.3 kJ/mol over the temperature range 360–440°C. The best wettability of molten AuSn solder balls on Au
foils occurred at 390°C (wetting angle is about 25°). Above 390°C, the higher solder oxidation rate retarded the wetting of
the molten AuSn solder. 相似文献
19.
The feasibility of thermosonic gold wire bonding on Cu coupons with Sn/Cu metallizations was studied by evaluating shear strength
and microstructure of balls bonded on different Sn metallization samples. The 0.85 ± 0.08 μm and 5.34 ± 0.21 μm thick metallizations were produced by dipping the Cu coupon in 250°C molten Sn solder for 1 s (sample 1) and 30 s (sample
2), respectively. Cu6Sn5 intermetallic compounds are formed during dipping. After wire bonding, Au-Cu-Sn layers are found on the ball-coupon interface
of both samples. The highest ball shear force observed was 40 gf (1 gf = 9.81 mN) and was achieved on sample 1 using 520 mW
and 40 gf of ultrasonic power and bonding force, respectively. The shear fracture goes through the Au ball. The Sn is squeezed
out of the contact zone during wire bonding and forms flashes that extend 5 μm and 25 μm beyond the contact zone for samples 1 and 2, respectively. 相似文献
20.
Kang S.K. Shih D.Y. Fogel K. Lauro P. Myung-Jin Yim Advocate G.G. Jr. Griffin M. Goldsmith C. Henderson D.W. Gosselin T.A. King D.E. Konrad J.J. Sarkhel A. Puttlitz K.J. 《Electronics Packaging Manufacturing, IEEE Transactions on》2002,25(3):155-161
Recently, the research and development activities for replacing Pb-containing solders with Pb-free solders have been intensified due to both competitive market pressures and environmental issues. As a result of these activities, a few promising candidate solder alloys have been identified, mainly, Sn-based alloys. A key issue affecting the integrity and reliability of solder joints is the interfacial reactions between a molten solder and surface finishes in the solder joint structures. In this paper, a fundamental study of the interfacial reactions between several Pb-free candidate solders and surface finishes commonly used in printed-circuit cards is reported. The Pb-free solders investigated include Sn-3.5 Ag, Sn-3.8 Ag-0.7 Cu, and Sn-3.5 Ag-3.0 Bi. The surface finishes investigated include Cu, Au/Ni(P), Au/Pd/Ni(P), and Au/Ni (electroplated). The reaction kinetics of the dissolution of surface finishes and intermetallic compound growth have been measured as a function of reflow temperature and time. The intermetallic compounds formed during reflow reactions have been identified by SEM with energy dispersive x-ray spectroscopy. 相似文献