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1.
S. F. Corbin 《Journal of Electronic Materials》2005,34(7):1016-1025
During this investigation, a high-temperature, variable melting point (VMP) Sn-Sb solder paste was developed. The solder was
created by mixing pure Sn and Sb powders together with a flux to form a paste. The proper choice of flux composition and Sn
powder size resulted in a Sn-10wt.%Sb solder paste that had an initial melting point of 232°C and solder ball formation at
peak temperatures as low as 241°C. This represents a significant reduction in the process temperature that would normally
be required for a prealloyed solder with a melting point of 250°C. When this solder paste is reheated, significant remelting
does not take place until a temperature above 241°C is reached. In this way, the solder exhibits a VMP. Experiments indicate
that this VMP behavior is due to isothermal solidification (or freezing) at the solder temperature owing to the partial transient
liquid-phase (TLP) behavior of the solder powder paste. 相似文献
2.
A mechanical alloying (MA) process was used to produce lead-free solder pastes of Sn-3.5Ag and the Sn-3.5Ag-4Bi system. Because
of the high energy induced by repeated fracturing and welding, the grinding media played an important role during the MA process.
A ceramic container was used to provide stronger impact force, which could induce phase transformation better than a Teflon
container. In addition, it was found that 1-cm balls could fracture Bi particles and promote their dissolution into the Sn
matrix. On the contrary, the milling process tended to achieve homogeneous mixing when using 3-mm balls. The MA powders, after
milling with 3-mm balls, showed a small endothermic peak from the differential scanning calorimetry (DSC) profile at around
138°C, which was the eutectic temperature of Sn-Bi. The melting points of the MA powders in the ceramic container were measured
to be 221°C and 203°C, respectively, for Sn-3.5Ag and Sn-3.5Ag-4Bi from the DSC curves. The reduced melting point ensured
the complete melting during reflow with a peak temperature of 240°C. The formation of Ag3Sn was also observed from the x-ray diffraction peaks, indicating successful alloying by MA. The solder pastes could, thus,
be produced by adding flux into the MA powders. The wetting property of the solder joint was also evaluated. The as-prepared
solder pastes on electroless Ni-P/Cu/Si showed good metallurgical bonding with a contact angle less than 20°. 相似文献
3.
The intermetallic compounds (IMCs) formed at the interface between the Sn-9Zn-1.5Ag-0.5Bi lead-free solder alloy and unfluxed
Cu substrate have been investigated by x-ray diffraction, optical microscopy, scanning electron microscopy (SEM), and energy-dispersive
spectrometry (EDS). The melting point and melting range of the Sn-9Zn-1.5Ag-0.5Bi solder alloy are determined as 195.9°C and
10°C, respectively, by differential scanning calorimetry (DSC). Cu6Sn5 and Cu5Zn8 IMCs are formed between the Sn-9Zn-1.5Ag-0.5Bi/unfluxed Cu substrate wetted at 250°C for 10 sec. The interfacial adhesion
strength changes from 10.27±0.68 MPa to 8.58±0.59 MPa when soldering time varies from 10 sec to 30 sec at 250°C. 相似文献
4.
Nano-sized, nonreacting, noncoarsening oxide dispersoids have been incorporated into solder alloys to create a new, improved
solder structure with an ultrafine grain size of ∼200–500 nm. The new solders exhibit significantly enhanced creep resistance
combined with increased strength. The well-known thermal instability problem with ultrafine-grained structure appears to have
been overcome in these solder alloys and the microstructure was seen to be quite stable upon high temperature exposure (e.g.
120°C). This is attributed to the presence of very fine dispersoid particles which impede grain boundary sliding and dislocation
movement. The dispersions are seen to have a profound effect on the mechanical deformation characteristics of the solders
with respect to creep. As much as three orders of magnitude reduction in the steady state creep rate has been achieved. The
new solders also exhibit improved ductility under high strain rate deformation and improved strength (4–5 times higher tensile
strength) at low strain rates. It is demonstrated that with a dispersion of TiO2 particles, the Pb-Sn eutectic solder with a melting point of 183°C can be made more creep-resistant than the 80Au-20Sn eutectic
solder with a much higher melting point of 278°C. The new creep-resistant solders can be useful for optical and optoelectronic
packaging in which dimensional stability of the assembled structure is essential. 相似文献
5.
The effects of two different fluxes (A6 and B6) on the wetting performance of Sn-3.5Ag-0.5Cu lead-free solder balls were investigated
during the reflow process. Solder ball wetting behavior in real time via an optical microscope coupled with a video recorder
during the reflow process was studied. The lead-free solder balls started to melt and wet at 210°C by using A6, which is 8°C
lower than the melting point (218°C) of the solder material used. The wetting performance of the lead-free solder ball was
dramatically enhanced by using A6. The wettability test indicated that the height of the solder ball after the reflow process
with flux A6 was significantly lower than that with B6. It was found that strong fluxing capability caused these phenomena. 相似文献
6.
New,lead-free solders 总被引:2,自引:0,他引:2
Two specific examples of the new lead-free alloys are described. In the Sn-3.5%Ag-l%Zn alloy (m.p.~217°C), the eutectic precipitate
morphology is refined by the relatively small amount of zinc addition and as a result, a high-strength, high-ductility solder
with significantly improved creep resistance is obtained. As a temperature equivalent drop-in replacement for the Pb-Sn eutectic
alloy (m.p.~183°C), Sn-Zn-In based alloys (m.p.~185°C) have been developed. The addition of indium to the Sn-Zn binary system
improves the wetting characteristics of the alloy and lowers the melting temperature. 相似文献
7.
To achieve precise, hermetic, and reliable optoelectronic packaging, we studied a novel technology for bonding fibers to v-grooved
chips by metallic soldering. Multilayered metallization of Ti/Au, Ti/Cu/Au, or Ti/Ni/Au has been prepared to improve the poor
bonding nature of solder on oxide surface. The eutectic 43Sn57Bi (wt.%) alloy, having a melting point of 139°C, was selected
to bond the fibers to v-grooved chips. The alignment and adhesion tests result show that the precision packaging by soldering
has a satisfied reliability in the range of working temperature from −40°C to 85°C. The metallic solder bonding is hermetic,
and hence, it can isolate the optical device from ambient environment. 相似文献
8.
The creep behavior of In-Ag eutectic solder joints 总被引:7,自引:0,他引:7
The addition of 3 wt.% Ag to In results in a eutectic composition with improved mechanical properties while only slightly
lowering the melting temperature. Steady-state creep properties of In-Ag eutectic solder joints have been measured using constant
load tests at 0, 30, 60, and 90°C. Constitutive equations are derived to describe the creep behavior. The data are well represented
by an equation of the form proposed by Dorn: a power-law equation applies to each independent creep mechanism. Two parallel
mechanisms were observed for the In-Ag eutectic joints. The high-stress mechanism is a bulk mechanism with a thermal dependence
dominated by the thermal dependence of creep in the Inrich matrix. The low-stress mechanism is a grain boundary mechanism.
Results of this work are discussed with regard to creep behavior of typical eutectic systems. 相似文献
9.
Yoshikazu Takaku Komei Makino Keita Watanabe Ikuo Ohnuma Ryosuke Kainuma Yasushi Yamada Yuji Yagi Ikuo Nakagawa Takashi Atsumi Kiyohito Ishida 《Journal of Electronic Materials》2009,38(1):54-60
The Zn-Al(-Cu) eutectic alloys (melting point 381°C) are candidates for use as Pb-free high-temperature solders as a substitute
for Pb-based solders, which are suitable for severe working environments such as the engine room of hybrid vehicles equipped
with an inverter system as well as a heat engine. In this study, the interfacial reaction between Zn-Al(-Cu) alloys and the
Ni substrate during soldering, aging, and thermal cycling was investigated. Semiconductor chips and Ni substrates were soldered
with Zn-Al(-Cu) alloys at various temperatures under a nitrogen atmosphere. The soldered assemblies were then heat-treated
at 200°C and 300°C to examine the microstructural evolution at the soldered interface. The effect of severe thermal cycles
between −40°C and 250°C in air on the microstructure and fracture behavior at the solder joint was investigated. Even after
a 1000-cycle test, the thickness of the Al3Ni2 layer formed at the interface between the Zn-Al-based solder and the Ni substrate, which is responsible for the damage of
the soldered assemblies, was quite small. 相似文献
10.
T. H. Chuang S. Y. Chang L. C. Tsao W. P. Weng H. M. Wu 《Journal of Electronic Materials》2003,32(3):195-200
The intermetallic compounds formed at the interfaces between In-49Sn solder balls and Au/Ni/Cu pads during the reflow of In-49Sn
solder, ball-grid array (BGA) packages are investigated. Various temperature profiles with peak temperatures ranging from
140°C to 220°C and melting times ranging from 45 sec to 170 sec are plotted for the reflow processes. At peak temperatures
below 170°C, a continuous double layer of intermetallics can be observed, showing a composition of Au(In,Ni)2/Au(In,Ni). Through selective etching of the In-49Sn solders, the intermetallic layer is made up of irregular coarse grains.
In contrast, a number of cubic-shaped AuIn2 intermetallic compounds appear at the interfaces and migrate toward the upper domes of In-49Sn solder balls after reflow
at peak temperatures above 200°C for longer melting times. The upward floating of the AuIn2 cubes can be explained by a thermomigration effect caused by the temperature gradient present in the liquid solder ball.
The intermetallic compounds formed under various reflow conditions in this study exhibit different types of morphology, yet
the ball shear strengths of the solder joints in the In-49Sn BGA packages remain unaffected. 相似文献
11.
Nanoparticles of the Lead-free Solder Alloy Sn-3.0Ag-0.5Cu with Large Melting Temperature Depression
Chang Dong Zou Yu Lai Gao Bin Yang Xin Zhi Xia Qi Jie Zhai Cristina Andersson Johan Liu 《Journal of Electronic Materials》2009,38(2):351-355
Due to the toxicity of lead (Pb), Pb-containing solder alloys are being phased out from the electronics industry. This has
lead to the development and implementation of lead-free solders. Being an environmentally compatible material, the lead-free
Sn-3.0Ag-0.5Cu (wt.%) solder alloy is considered to be one of the most promising alternatives to replace the traditionally
used Sn-Pb solders. This alloy composition possesses, however, some weaknesses, mainly as a result of its higher melting temperature
compared with the Sn-Pb solders. A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy
particle size down to the nanometer range. The melting temperature of Sn-3.0Ag-0.5Cu lead-free solder alloy, both as bulk
and nanoparticles, was investigated. The nanoparticles were manufactured using the self-developed consumable-electrode direct
current arc (CDCA) technique. The melting temperature of the nanoparticles, with an average size of 30 nm, was found to be
213.9°C, which is approximately 10°C lower than that of the bulk alloy. The developed CDCA technique is therefore a promising
method to manufacture nanometer-sized solder alloy particles with lower melting temperature compared with the bulk alloy. 相似文献
12.
M. MC Cormack I. Artaki S. Jin A. M. Jackson D. M. Machusak G. W. Kammlott D. W. Finley 《Journal of Electronic Materials》1996,25(7):1128-1131
Wave soldering with low solid fluxes at temperatures as low as 175°C on test boards with a Cu/Imidazole surface finish has
been shown to be feasible using a Pb-free, Bi-45%Sn-0.33%Ag solder that melts at temperatures of ∼140∼145°C. Other surface
finishes such as Pd/Ni, Au/Ni, and Bi exhibit unacceptable soldering at temperatures below 210°C. Intermediate in performance
are Sn surface finishes, which exhibit acceptable soldering at 190°C, but not at 175°C. Acceptable joints wave soldered on
Cu/Im finishes passed class I/II inspection criterion and exhibited pull strengths in excess of the ultimate strength of the
component leads. 相似文献
13.
Electromigration (EM) parameters in the eutectic SnPb solder were measured using the edge displacement method (EDM) and an atomic force microscope (AFM) in the temperature range of 60° to 140°C. The measured drift velocity was found to be 0.3 Å/sec when the solder stripe was stressed under 4.9×104 A/cm2 at 80°C, and it increased as the current density or the temperature increased. The products of DZ* at 60°C, 80°C, 100°C, 120°C, and 140°C were also obtained. In addition, the EM activation energy was determined to be 0.45 eV at the temperature range 60–100°C and 0.55 eV at the temperature range 100–140°C. These two activation energies may correspond to the Sn and Pb diffusion at the two temperature ranges. These values are very fundamental to current-carrying capability and mean-time-to-failure measurement for solder joints. 相似文献
14.
Study of Low-Temperature Thermocompression Bonding
in Ag-In Solder for Packaging Applications 总被引:1,自引:0,他引:1
Riko I Made Chee Lip Gan Li Ling Yan Aibin Yu Seung Wook Yoon John H. Lau Chengkuo Lee 《Journal of Electronic Materials》2009,38(2):365-371
Low-temperature solders have wide applications in integrated circuits and micro-electromechanical systems packaging. In this
article, a study on Ag-In solder for chip-to-chip thermocompression bonding was carried out. The resulting joint consists
of AgIn2 and Ag9In4 phases, with the latter phase having a melting temperature higher than 400°C. Complete consumption of In solder into a Ag-rich
intermetallic compound is achieved by applying a bond pressure of 1.4 MPa at 180°C for 40 min. We also observe that the bonding
pressure effect enables a Ag-rich phase to be formed within a shorter bonding duration (10 min) at a higher pressure of 1.6 MPa.
Finally, prolonged aging leads to the formation of the final phase of Ag9In4 in the bonded joints. 相似文献
15.
SnAgCu alloy with low melting point and good soldering property is a good candidate for the Sn/Pb eutectic. In this paper, SnAgCu nanoparticles were synthesized by a chemical reduction method. The particle size and the melting point are controlled by modifying the process parameters, including reaction temperature, surfactant concentration and dropping speed of precursor. The lowest melting onset temperature is observed at 199.1 °C, which is 18 °C lower than that of commercially available SnAgCu solder alloy. The tensile strength of the as-synthesized reaches 34.3 MPa, which reveals a good solderability property. 相似文献
16.
In this work, the melting characteristics and interfacial reactions of Sn-ball/Sn-3.0Ag-0.5Cu-paste/Cu (Sn/SAC305-paste/Cu) structure joints were studied using differential scanning calorimetry, in order to gain a deeper and broader understanding of the interfacial behavior and metallurgical combination among the substrate (under-bump metallization), solder ball and solder paste in a board-level ball grid array (BGA) assembly process, which is often seen as a mixed assembly using solder balls and solder pastes. Results show that at the SAC305 melting temperature of 217°C, neither the SAC305-paste nor the Sn-ball coalesce, while an interfacial reaction occurs between the SAC305-paste and Cu. A slight increase in reflow temperature (from 217°C to 218°C) results in the coalescence of the SAC305-paste with the Sn-ball. The Sn-ball exhibits premelting behavior at reflow temperatures below its melting temperature, and the premelting direction is from the bottom to the top of the Sn-ball. Remarkably, at 227°C, which is nearly 5°C lower than the melting point of pure Sn, the Sn-ball melts completely, resulting from two eutectic reactions, i.e., the reaction between Sn and Cu and that between Sn and Ag. Furthermore, a large amount of bulk Cu6Sn5 phase forms in the solder due to the quick dissolution of Cu substrate when the reflow temperature is increased to 245°C. In addition, the growth of the interfacial Cu6Sn5 layer at the SAC305-paste/Cu interface is controlled mainly by grain boundary diffusion, while the growth of the interfacial Cu3Sn layer is controlled mainly by bulk diffusion. 相似文献
17.
Thermodynamics of the Sn-In-Ag solder system 总被引:3,自引:0,他引:3
18.
Zn-Al-Mg-Ga alloys as Pb-free solder for die-attaching use 总被引:1,自引:0,他引:1
Zn-based alloys have been investigated to replace Pb-5%Sn solder for die-attaching use. We have found that a Zn-4%Al-3%Mg-3%Ga
alloy has a 309°C solidus and a 347°C liquidus. A die-attaching test was done with preforms of this alloy, Ag-plated lead-frames,
and Au-plated dummy dies. Good die-attaching with a small amount of voids can be achieved at 320°C or higher. In subsequent
reliability tests, no failure was observed until 1000 cycles between −65°C and 150°C or until 1000 h at 85°C and 85% humidity.
Although the poor workability and poor ability of stress relaxation at room temperature of this alloy may somewhat limit its
application areas, this solder is the first Pb-free solder for die-attaching use to our knowledge. 相似文献
19.
Rhodium(III) acetylacetonate was investigated for its physical, thermal and optical properties. Ultraviolet-visible absorption
spectra show absorptions at 320 nm, 260 nm, and 210 nm. Density measurements yielded a value of 1.75 g/cm3. Thermal characteristics were evaluated using differential thermal analysis (DTA). It was found that the compound is not
volatile, decomposing upon heating. If heating rates are rapid enough,e.g. > 2° C/min, melting at 267° C can be observed. If heating rates are slower, decomposition is complete below the melting point.
If the compound is annealed at 267° C for four hours decomposition is complete, yielding 99% pure rhodium metal. In an oxidizing
atmosphere, on the other hand, the compound decomposes into a product containing 75% rhodium metal which appears to be RhO2. 相似文献
20.
Mark A. Palmer Nicole S. Erdman David A. McCall 《Journal of Electronic Materials》1999,28(11):1189-1193
Eutectic lead-tin has been the solder of choice throughout the history of the electronics industry. Alternatives to this material
are now being considered because of environmental concerns, as well as the strength and temperature limitations of eutectic
lead-tin. Identifying and using these alternative materials poses significant challenges, many of which we believe can be
addressed if one forms solder joints through liquid phase enhanced sintering. First, most alternative solder materials have
significantly higher melting temperatures (than eutectic lead-tin), and their use would require the replacement of much of
the manufacturing infrastructure. In this work joints with shear stresses approaching that of eutectic lead-tin solder were
formed by sintering a eutectic tin-sliver solder paste (Tm=221°C) doped with 3 v/o eutectic Sn-Bi powder at 210°C for 30 min. Second, to date the industry has limited its consideration
to eutectic or near-eutectic alloys because of the concern of forming cold solder joints. In this work joints have been prepared
by sintering solder pastes with a wide thermal range at temperatures just above the solidus, where a small amount of liquid
will form and therefore enhance the rate of sintering, which have shear strengths of 6 MPa or higher. These findings indicate
that it may be worthwhile to investigate developing a sinterable solder paste, which can be used to prepare surface mount
assemblies. 相似文献