Fast Soldering Reactions on Au Foils

1996 ◽  
Vol 445 ◽  
Author(s):  
P.G. Kim ◽  
K.N. TU
Keyword(s):  
Intermetallic Compounds ◽  
Wetting Angle ◽  
High Solubility ◽  
Reflow Time ◽  
X Ray ◽  
Intermetallic Compound Growth ◽  
Wetting Behaviors ◽  
Pure Sn ◽  
Eutectic Snpb

AbstractWe have studied the wetting behaviors and interfacial reactions of Pb‐containing (63Sn‐37Pb, 95Pb‐5Sn) and Pb‐free solders (pure Sn, 96Sn‐4Ag, 57Bi‐43Sn, 77.2Sn‐20In‐2.8Ag) on Au foils in order to understand the role of Pb in Pb‐based solders. Surface morphology, wetting angle, and interfacial reaction of the solders were studied by Scanning Electron Microscopy (SEM) and Energy Dispersive X‐ray Analysis (EDX). Pb‐containing and Pb‐free solders (pure Sn, 96Sn‐4Ag, 77.2Sn‐20In‐2.8Ag) showed rough surfaces due to the precipitation of intermetallic compounds on the surface of the solder caps. The eutectic SnBi (57Bi‐43Sn) solder, however, showed a smoother surface. The wetting angle of the eutectic SnPb (63Sn‐37Pb), pure Sn, 96Sn‐4Ag, and 77.2Sn‐20In‐2.8Ag solders decreased significantly with reflow time, while the eutectic SnBi and 95Pb‐5Sn solders showed a much smaller decrease. A large amount of intermetallic compounds was formed throughout the entire region of the solder cap for the eutectic SnPb, 96Sn‐4Ag, 95Pb‐5Sn, and 77.2Sn‐20In‐2.8Ag, mainly due to the high solubility of Au in these solders. Slow intermetallic compound growth was observed for the eutectic SnBi solder.

Morphology of instability of the wetting tips of eutectic SnBi, eutectic SnPb, and pure Sn on Cu

1995 ◽  
Vol 10 (3) ◽  
pp. 497-504 ◽  
Author(s):  
H.K. Kim ◽  
H.K. Liou ◽  
K.N. Tu
Keyword(s):  
Solder Joint ◽  
Surface Morphology ◽  
Intermetallic Compounds ◽  
Rough Surface ◽  
Environmental Issue ◽  
Wetting Angle ◽  
Angle Change ◽  
Microelectronics Industry ◽  
Pure Sn ◽  
Eutectic Snpb

The Pb-based solder used in microelectronics industry is becoming an environmental issue. To understand the wetting behavior of solders with and without Pb, we have studied the surface morphology and wetting reaction of eutectic SnBi, eutectic SnPb, and pure Sn on Cu through the measurements of wetting angle change and wetting tip stability by SEM and EDX. The wetting angle remains constant after the initial spread, but the eutectic SnPb/Cu continues to react and forms a reaction band in front of the solder edge as well as intermetallic compounds at the interface. For eutectic SnBi/Cu, there is no reaction at the wetting tip, and the wetting angle does not change much; however, the interfacial reaction between eutectic SnBi and Cu forms intermetallic compounds at the solder joint; the wetting tip is not in a static equilibrium. A rough surface and edge was observed on the eutectic SnBi/Cu joint, but the eutectic SnPb/Cu has a smoother surface and edge.

Morphology of wetting reactions of SnPb alloys on Cu as a function of alloy composition

1998 ◽  
Vol 13 (1) ◽  
pp. 37-44 ◽  
Author(s):  
C. Y. Liu ◽  
K. N. Tu
Keyword(s):  
Free Energy ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Driving Force ◽  
Alloy Composition ◽  
Wetting Angle ◽  
Compound Formation ◽  
Side Band ◽  
Intermetallic Compound Formation ◽  
Pure Sn

We have investigated the wetting angle, side band growth, and intermetallic compound formation of seven SnPb alloys on Cu ranging from pure Sn to pure Pb. The wetting angle has a minimum near the middle composition and increases toward pure Sn and pure Pb, but the side band growth has a maximum near the middle composition. The intermetallic compounds formed are Cu6Sn5 and Cu3Sn for the eutectic and high-Sn alloys, yet for the high-Pb alloys, only Cu3Sn can be detected. While no intermetallic compound forms between Cu and pure Pb, the latter nevertheless wets the former with an angle of 115°. The driving force of a wetting reaction, which may be affected by the free energy gain in compound formation, is discussed by assuming that rate of compound formation is fast.

Wetting Behaviors of Sn-Based Solders on Cu and Pd Surfaces

1995 ◽  
Vol 390 ◽  
Author(s):  
H. K. Kim ◽  
Y. Wang ◽  
A. Maheshwari ◽  
K. N. Tu
Keyword(s):  
Surface Morphology ◽  
Classical Model ◽  
Layered Compound ◽  
Quasi Equilibrium ◽  
Compound Formation ◽  
Snpb Solder ◽  
Wetting Behaviors ◽  
Pure Sn ◽  
Compound Surface ◽  
Eutectic Snpb

ABSTRACTWe have studied the surface morphology and wetting reaction of eutectic SnBi, eutectic SnPb, and pure Sn on Cu and Pd surfaces. In the case of Pd, the reactions were so fast that no quasi-equilibrium wetting angle could be measured. The compound formation has changed not only the interfaces but also the surfaces. Due to the formation of a reaction band outside the solder cap, the SnPb solder is no longer wetting the Cu surface but rather the Cu-Sn compound surface. In the wetting interface between eutectic SnPb and Cu, the morphology of the scallop-like Cu-Sn compound grains shows that we may not apply the classical model of layered compound growth to analyze the rate of soldering reactions.

Creep Tendencies of Cu-Al Thin Wires Submitted to Moderate Temperature Conditions: Influence of Intermetallic Compounds

2016 ◽  
Vol 879 ◽  
pp. 631-636
Author(s):  
Antoine Gueydan ◽  
Eric Hug
Keyword(s):  
Intermetallic Compounds ◽  
Applied Stress ◽  
Automotive Industry ◽  
X Ray ◽  
Strain Behavior ◽  
Thin Wires ◽  
Operating Load ◽  
Initial Heat ◽  
Initial Heat Treatment

X-Ray analysis was performed on copper-clad aluminum wires at 423 K and 673 K to follow their microstructural evolution and understand their strain behavior under creep deformation, potential operating load in automotive industry. The lifetime of the wires is found to be strongly dependent on the existence of an initial heat treatment and on the applied stress. Annealed drawn wires verify a traditional Norton law in the overall range of the stress level. Raw drawn wires exhibit a distinct two stage behavior with a breakdown around an applied stress of 0.7 times the yield stress. It is shown in this work that the intermetallic compounds between copper and aluminum play only the role of a mechanical bounding without affecting the strain rate of the wires.

Size dependent dewetting and sideband reaction of eutectic SnPb on Au/Cu/Cr multilayered thin film

1998 ◽  
Vol 13 (5) ◽  
pp. 1103-1106 ◽  
Author(s):  
D. W. Zheng ◽  
Z. Y. Jia ◽  
C. Y. Liu ◽  
Weijia Wen ◽  
K. N. Tu
Keyword(s):  
Thin Film ◽  
Layered Structure ◽  
Solder Ball ◽  
Size Dependence ◽  
Wetting Angle ◽  
Multilayered Thin Film ◽  
Size Dependent ◽  
Pure Sn ◽  
Eutectic Snpb ◽  
Main Factor

Dewetting of eutectic SnPb on blank Au(500 Å)/Cu(1 μm)/Cr(800 Å) layered structure was found to have a solder size dependence. At 250 °C, if the solder weight fell below 4 mg, dewetting occurred from the center of the solder cap; if the solder weight went beyond 6 mg, dewetting happened from the cap edge. In the latter case, a smaller cap with a higher wetting angle was formed at the center and a ring of solder was left around the edge. Large voids were left in the solder cap after dewetting in both cases. In contrast, all solder caps were found to dewet from the edge on a patterned film at 250 °C if the solder ball was large enough to wet the whole film initially, irrespective of the solder size. For comparison, pure Sn, eutectic SnAg, and eutectic SnBi caps also dewetted from the edge of the Au/Cu/Cr thin film, irrespective of the solder size or whether the substrate was patterned. Since eutectic SnPb on blank Au/Cu/Cr is the only case in which a large sideband growth was found and the dewetting occurred from the center, we postulated sideband to be the main factor which controls the unusual dewetting. The link between them is discussed.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

The role of silicon in forages: A quantitative X-Ray study

1987 ◽  
Vol 45 ◽  
pp. 416-417
Author(s):  
Janet H. Woodward ◽  
D. E. Akin
Keyword(s):  
Sodium Acetate ◽  
Dry Matter ◽  
Acetate Buffer ◽  
Plant Tissues ◽  
Sodium Acetate Buffer ◽  
X Ray ◽  
Dry Matter Digestibility ◽  
Percent Composition

Silicon (Si) is distributed throughout plant tissues, but its role in forages has not been clarified. Although Si has been suggested as an antiquality factor which limits the digestibility of structural carbohydrates, other research indicates that its presence in plants does not affect digestibility. We employed x-ray microanalysis to evaluate Si as an antiquality factor at specific sites of two cultivars of bermuda grass (Cynodon dactvlon (L.) Pers.). “Coastal” and “Tifton-78” were chosen for this study because previous work in our lab has shown that, although these two grasses are similar ultrastructurally, they differ in in vitro dry matter digestibility and in percent composition of Si.Two millimeter leaf sections of Tifton-7 8 (Tift-7 8) and Coastal (CBG) were incubated for 72 hr in 2.5% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0. For controls, sections were incubated in the sodium acetate buffer or were not treated.

Pathophysiological function of the mitochondria as a calcium reservoir: Quantitative x-ray microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 164-165
Author(s):  
K. Teraoka ◽  
N. Kaneko ◽  
Y. Horikawa ◽  
T. Uchida ◽  
R. Matsuda ◽  
...  
Keyword(s):  
Bolus Injection ◽  
Contact Method ◽  
X Ray

The aim of this study was to elucidate the role of the mitochondria as a store of calcium(Ca) under the condition of pathophysiological Ca overload induced by a rise in extracellular Ca concentration and the administration of isoproterenol.Eight rats were employed, and hearts were perfused as in the Langendorff method with Krebs-Henseleit solution gassed with 95% O2 and 5% CO2. Tow specimens were perfused with 2mM Ca for 30 min, and 2 were perfused with 5.5 mM Ca for 20 min. 4 specimens were perfused with 2 mM Ca for 5 min, and of these 4, 2 were infused with 10-7 mM/kg/min. isoproterenol for 5 min, and 2 were given a bolus injection of 3 x 10-7 mM isoproterenol. After rapid-cryofixation by the metal-mirror contact method with a Reichert-Jung KF80/MM80, and cryosectioning at -160 to -180° C with a Reichert-Jung Ultracut Fc-4E, ultrathin specimens (100nm) were free-ze-dreid for several hours at 10-5 Torr in the JEOL FD 7000, and mitochondrial Ca was determined by quantitative x-ray micranalysis (JEOL 1200EX, LINK AN 10000S).

Ionic homeostasis and subcellular element compartmentation

1990 ◽  
Vol 48 (2) ◽  
pp. 150-151
Author(s):  
Ann LeFurgey ◽  
Peter Ingram ◽  
J.J. Blum ◽  
M.C. Carney ◽  
L.A. Hawkey ◽  
...  
Keyword(s):  
Leishmania Major ◽  
Ionic Homeostasis ◽  
X Ray ◽  
Functional Studies ◽  
Cell Compartments ◽  
X Ray Imaging ◽  
Resolution Electron ◽  
Multiple Cell ◽  
Role Of Zn

Subcellular compartments commonly identified and analyzed by high resolution electron probe x-ray microanalysis (EPXMA) include mitochondria, cytoplasm and endoplasmic or sarcoplasmic reticulum. These organelles and cell regions are of primary importance in regulation of cell ionic homeostasis. Correlative structural-functional studies, based on the static probe method of EPXMA combined with biochemical and electrophysiological techniques, have focused on the role of these organelles, for example, in maintaining cell calcium homeostasis or in control of excitation-contraction coupling. New methods of real time quantitative x-ray imaging permit simultaneous examination of multiple cell compartments, especially those areas for which both membrane transport properties and element content are less well defined, e.g. nuclei including euchromatin and heterochromatin, lysosomes, mucous granules, storage vacuoles, microvilli. Investigations currently in progress have examined the role of Zn-containing polyphosphate vacuoles in the metabolism of Leishmania major, the distribution of Na, K, S and other elements during anoxia in kidney cell nuclel and lysosomes; the content and distribution of S and Ca in mucous granules of cystic fibrosis (CF) nasal epithelia; the uptake of cationic probes by mltochondria in cultured heart ceils; and the junctional sarcoplasmic retlculum (JSR) in frog skeletal muscle.

Silicon Substitution for Calcium in the Shell of the Fingernail Clam, Musculium Transversum Studied By X-Ray Analysis

1980 ◽  
Vol 38 ◽  
pp. 560-561
Author(s):  
Judith A. Murphy ◽  
Anthony Paparo ◽  
Richard Sparks
Keyword(s):  
Carbonic Anhydrase ◽  
River Water ◽  
Food Chains ◽  
Well Water ◽  
Shell Formation ◽  
X Ray ◽  
Molluscan Shell ◽  
Fingernail Clams

Fingernail clams (Muscu1ium transversum) are dominant bottom-dwelling animals in some waters of the midwest U.S. These organisms are key links in food chains leading from nutrients in water and mud to fish and ducks which are utilized by man. In the mid-1950’s, fingernail clams disappeared from a 100-mile section of the Illinois R., a tributary of the Mississippi R. Some factor(s) in the river and/or sediment currently prevent clams from recolonizing areas where they were formerly abundant. Recently, clams developed shell deformities and died without reproducing. The greatest mortality and highest incidence of shell deformities appeared in test chambers containing the highest proportion of river water to well water. The molluscan shell consists of CaCO3, and the tissue concerned in its secretion is the mantle. The source of the carbonate is probably from metabolic CO2 and the maintenance of ionized Ca concentration in the mantle is controlled by carbonic anhydrase. The Ca is stored in extracellular concentric spherical granules(0.6-5.5μm) which represent a large amount of inertCa in the mantle. The purpose of this investigation was to examine the role of raw river water and well water on shell formation in the fingernail clam.

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