Growth Rate of Solder Intermetallics

1993 ◽  
Vol 316 ◽  
Author(s):  
J. D. Demaree
Keyword(s):  
Growth Rate ◽  
Solder Joint ◽  
Elevated Temperatures ◽  
Rutherford Backscattering Spectrometry ◽  
Formation Rate ◽  
Compound Formation ◽  
Intermetallic Growth ◽  
Depth Sensitivity ◽  
Sputter Deposited ◽  
Pbsn Solder

ABSTRACTThe formation of intermetallic layers between copper wires and lead-tin solders is indicative of the strong metallurgical bond required for a durable solder joint Previous studies have shown that these interracial compounds grow at significant rates (up to 1 µm/day at 100°C), and differences in thermal expansion and hardness between the metals and the intermetallics can lead to the mechanical failure of the solder joint during service. Most previous measurements of the compound formation rate have used elevated temperatures to facilitate the direct observation of the intermetallic thickness by optical microscopy, SEM, or TEM. In this study, Rutherford backscattering spectrometry (RBS) has been used to study the intermetallic growth rate using sputter-deposited thin films of Cu and PbSn. The extraordinary depth sensitivity of RBS (~10 nm) allows these measurements to be made in relatively short times, without the need for heat treatment to accelerate the reaction. Measurements have indicated that at least 23 nm of Cu6Sn5 and 30 nm of Cu3Sn form between Cu and PbSn solder in less than one hour. Faster deposition methods are being investigated to further characterize this rapid reaction. Iron has been proposed as a diffusion barrier material to inhibit intermetallic growth in solder joints. Preliminary measurements of the solder/Fe reaction indicates a much slower rate of growth, with less than 50 nm of total intermetallic forming over 8 hours.

Investigation of Chromium Nitridation Using Ion Beam Resonance Analysis

1994 ◽  
Vol 337 ◽  
Author(s):  
S.W. Russell ◽  
A.E. Bair ◽  
M.J. Rack ◽  
D. Adams ◽  
R.L. Spreitzer ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Ion Beam ◽  
Oxygen Impurity ◽  
X Ray Diffraction ◽  
Resonance Analysis ◽  
Depth Sensitivity ◽  
Sputter Deposited ◽  
Nitride Layers ◽  
Chromium Films ◽  
Sample Configuration

ABSTRACTWe investigate the nitridation of chromium films in an NH3 ambient at 500°C. Rutherford backscattering spectrometry using 2.0 MeV He2+ was utilized to determine the compositions of thick reacted layers and to provide calibration for the other techniques. In addition, analysis was performed using the 14N(α,α)14N resonance at 3.72 MeV in order to enhance sensitivity to nitrogen. Sputter-deposited TiN was used as a calibration for the cross section a for this resonance over the energy range 3.05-3.85 MeV and compared to the literature value. We find that analysis just above the peak in the resonance provides excellent sensitivity to N concentration in the nitride layers. This approach may be readily used in conjunction with 2.0 MeV backscattering to determine the overall composition and sample configuration. Auger electron spectroscopy was used to provide more depth sensitivity in compositional profiling and to monitor the oxygen impurity distribution. X-ray diffraction was used to identify phases in both as-deposited and annealed films.

The threshold energy for atom displacement in fcc metals

1990 ◽  
Vol 48 (4) ◽  
pp. 530-531
Author(s):  
Wilfried Sigle ◽  
Matthias Hohenstein ◽  
Alfred Seeger
Keyword(s):  
Growth Rate ◽  
Elevated Temperatures ◽  
Threshold Energy ◽  
Dislocation Loops ◽  
Absolute Minimum ◽  
Voltage Electron ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Fcc Metal

Prolonged electron irradiation of metals at elevated temperatures usually leads to the formation of large interstitial-type dislocation loops. The growth rate of the loops is proportional to the total cross-section for atom displacement,which is implicitly connected with the threshold energy for atom displacement, Ed . Thus, by measuring the growth rate as a function of the electron energy and the orientation of the specimen with respect to the electron beam, the anisotropy of Ed can be determined rather precisely. We have performed such experiments in situ in high-voltage electron microscopes on Ag and Au at 473K as a function of the orientation and on Au as a function of temperature at several fixed orientations.Whereas in Ag minima of Ed are found close to <100>,<110>, and <210> (13-18eV), (Fig.1) atom displacement in Au requires least energy along <100>(15-19eV) (Fig.2). Au is thus the first fcc metal in which the absolute minimum of the threshold energy has been established not to lie in or close to the <110> direction.

Investigation of Pt Bottom Electrodes for "In-Situ" Deposited Pb(Zr,Ti)O3 (PZT) thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Rainer Bruchhaus ◽  
Dana Pitzer ◽  
Oliver Eibl ◽  
Uwe Scheithauer ◽  
Wolfgang Hoesler
Keyword(s):  
Elevated Temperatures ◽  
Diffusion Processes ◽  
Rutherford Backscattering Spectrometry ◽  
Layer Sequence ◽  
Si Substrates ◽  
Transmission Electron ◽  
In Situ Deposition ◽  
Electron Spectrometry ◽  
Heating Up

AbstractThe deposition of the bottom electrode plays a key role in the fabrication of ferroelectric capacitors. Processing at elevated temperatures of up to 800°C can give rise to diffusion processes and thereof formation of harmful dielectric layers.In this paper we used Rutherford backscattering spectrometry (RBS), Auger electron spectrometry (AES) and transmission electron microscopy (TEM) to study Pt/Ti/SiO2/Si substrates with various thicknesses of the Ti and Pt layers. During heating up to about 450°C in vacuum the initial layer sequence remains unchanged. However, drastic changes occur when the electrodes are exposed to Ar/O2 atmosphere during heat treatment. Oxidation induced diffusion of Ti into Pt and oxidation of Ti were observed. A Pt electrode with a 100 nm thick Ti adhesion layer proved to be suitable for the "in-situ" deposition of PZT films.

A Mechanism of Polycrystallization in Fully Lamellar Ti-48Al-8Nb Single Crystal Alloy Aged at Elevated Temperatures

2002 ◽  
Vol 753 ◽  
Author(s):  
Yukinori Yamamoto ◽  
Masao Takeyama ◽  
Takashi Matsuo
Keyword(s):  
Growth Rate ◽  
Diffusion Coefficient ◽  
Single Crystal ◽  
Grain Growth ◽  
Elevated Temperatures ◽  
Volume Diffusion ◽  
Activation Enthalpy ◽  
Lamellar Microstructure ◽  
Aged Sample ◽  
Fully Lamellar

ABSTRACTPolycrystallization mechanism of a fully lamellar microstructure during aging at 1473 and 1273 K has been examined using Ti-48Al-8Nb fully lamellar single crystal, which consists mostly of γ/γ interfaces (variant, perfect-twin and pseudo-twin boundaries). After a certain period of aging, a few γ grains are formed within the lamellae and the lamellar microstructure collapses rapidly to become a γ grained microstructure at both temperatures. An EBSP analysis for aged sample revealed that most of the grains follow the orientation of variant domains in the lamellar microstructure. A kinetic analysis of the grain growth during aging revealed that the activation enthalpy of the growth rate is estimated to be 390 kJ/mol, which is very close to that for volume diffusion coefficient of Al and Nb in γ-TiAl. Based on the results, it is concluded that the formation of the grains is attributed to coarsening of variant domains within the lamellar plates and coalescence of the same variant domains across the lamellae, leading to a γ grained microstructure following the orientation of variant domains. These reactions also make the number of the variant domains decrease during aging, which remains only two variant domains with perfect-twin relationship.

Microbial community composition is linked to Sphagnum acclimation to warming

2021 ◽  
Author(s):  
Tatjana Živković ◽  
Alyssa A Carell ◽  
Gustaf Granath ◽  
Mats B Nilsson ◽  
Manuel Helbig ◽  
...  
Keyword(s):  
Growth Rate ◽  
Host Plant ◽  
Climate Warming ◽  
Elevated Temperatures ◽  
Critical Role ◽  
Temperature Acclimation ◽  
Microbial Interactions ◽  
Germ Free ◽  
Wide Range ◽  
Thermal Origin

&lt;p&gt;Peatlands store about third of the terrestrial carbon (C) and exert long-term climate cooling. Dominant plant genera in acidic peatlands, &lt;em&gt;Sphagnum&lt;/em&gt; mosses, are main contributors to net primary productivity. Through associative relationships with diverse microbial organisms (microbiome), &lt;em&gt;Sphagnum&lt;/em&gt; mosses control major biogeochemical processes, namely uptake, storage and potential release of carbon and nitrogen. Climate warming is expected to negatively impact C accumulation in peatlands and alter nutrient cycling, however &lt;em&gt;Sphagnum&lt;/em&gt;-dominated peatland resilience to climate warming may depend on &lt;em&gt;Sphagnum&lt;/em&gt;-microbiome associations. The ability of the microbiome to rapidly acclimatize to warming may aid &lt;em&gt;Sphagnum&lt;/em&gt; exposed to elevated temperatures through host-microbiome acquired thermotolerance. We investigated the role of the microbiome on &lt;em&gt;Sphagnum&lt;/em&gt;&amp;#8217;s ability to acclimate to elevated temperatures using a microbiome-transfer approach to test: a) whether the thermal origin of the microbiome influences acclimation of &lt;em&gt;Sphagnum&lt;/em&gt; growth and b) if microbial benefits to &lt;em&gt;Sphagnum&lt;/em&gt; growth depend on donor &lt;em&gt;Sphagnum&lt;/em&gt; species.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Using a full-factorial design, microbiomes were separated from &lt;em&gt;Sphagnum&lt;/em&gt; &amp;#8220;donor&amp;#8221; species from four different peatlands across a wide range of thermal environments (11.4-27&amp;#176;C). The microbiomes were transferred onto germ-free &amp;#8220;recipient&amp;#8221; &lt;em&gt;Sphagnum&lt;/em&gt; species in the laboratory and exposed to a range of experimental temperatures (8.5 &amp;#8211; 26.5&amp;#176;C) for growth analysis over 4 weeks.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Normalized growth rates were maximized for plants that received a microbiome from a matched &amp;#8220;donor&amp;#8221; and with a similar origin temperature (&amp;#916;T&lt;sub&gt;treatment-origin&lt;/sub&gt;: 0.3&amp;#177;0.9&amp;#176;C [&amp;#177;standard error], p = 0.73). For non-matched &amp;#8220;donor-recipient&amp;#8221; &lt;em&gt;Sphagnum&lt;/em&gt; pairs, &amp;#916;T&lt;sub&gt;treatment-origin&lt;/sub&gt; was slightly negative with -4.1&amp;#177;2.1&amp;#176;C (p = 0.06). The largest growth rate of the &amp;#8220;recipient&amp;#8221; was measured when grown with a microbiome from a matching &amp;#8220;donor&amp;#8221; &lt;em&gt;Sphagnum&lt;/em&gt; species and was 252% and 48% larger than the maximum growth rate of the germ-free &lt;em&gt;Sphagnum&lt;/em&gt; and the non-matched &amp;#8220;donor-recipient&amp;#8221; &lt;em&gt;Sphagnum&lt;/em&gt; pairs, respectively.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Our results suggest that the composition of the &lt;em&gt;Sphagnum&lt;/em&gt; microbiome plays a critical role in host plant temperature acclimation. We found that microbially-provided benefits to the host plant were most pronounced when: 1) the thermal origin of the microbiome is similar to experimental temperatures, and 2) when donor and recipient &lt;em&gt;Sphagnum&lt;/em&gt; species are the same. Together, these results suggest that &lt;em&gt;Sphagnum&lt;/em&gt; temperature acclimation can be modulated, in part, by microbial interactions and may potentially play a role in peatland resilience to climate warming.&lt;/p&gt;

scholarly journals Characterization of Urban New Particle Formation in Amman—Jordan

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 79 ◽  
Author(s):  
Tareq Hussein ◽  
Nahid Atashi ◽  
Larisa Sogacheva ◽  
Simo Hakala ◽  
Lubna Dada ◽  
...  
Keyword(s):  
Growth Rate ◽  
Eastern Mediterranean ◽  
Seasonal Pattern ◽  
Formation Rate ◽  
Particle Formation ◽  
New Particle Formation ◽  
Vapor Source ◽  
Back Trajectories ◽  
Pattern Maximum ◽  
The Mean

We characterized new particle formation (NPF) events in the urban background of Amman during August 2016–July 2017. The monthly mean of submicron particle number concentration was 1.2 × 104–3.7 × 104 cm−3 (exhibited seasonal, weekly, and diurnal variation). Nucleation mode (10–15 nm) concentration was 0.7 × 103–1.1 × 103 cm−3 during daytime with a sharp peak (1.1 × 103–1.8 × 103 cm−3) around noon. We identified 110 NPF events (≈34% of all days) of which 55 showed a decreasing mode diameter after growth. The NPF event occurrence was higher in summer than in winter, and events were accompanied with air mass back trajectories crossing over the Eastern Mediterranean. The mean nucleation rate (J10) was 1.9 ± 1.1 cm−3 s−1 (monthly mean 1.6–2.7 cm−3 s−1) and the mean growth rate was 6.8 ± 3.1 nm/h (4.1–8.8 nm/h). The formation rate did not have a seasonal pattern, but the growth rate had a seasonal variation (maximum around August and minimum in winter). The mean condensable vapor source rate was 4.1 ± 2.2 × 105 molecules/cm3 s (2.6–6.9 × 105 molecules/cm3 s) with a seasonal pattern (maximum around August). The mean condensation sink was 8.9 ± 3.3 × 10−3 s−1 (6.4–14.8 × 10−3 s−1) with a seasonal pattern (minimum around June and maximum in winter).

scholarly journals Fracture Properties of Concrete in Dry Environments with Different Curing Temperatures

2020 ◽  
Vol 10 (14) ◽  
pp. 4734
Author(s):  
Zhengxiang Mi ◽  
Qingbin Li ◽  
Yu Hu ◽  
Chunfeng Liu ◽  
Yu Qiao
Keyword(s):  
Fracture Toughness ◽  
Growth Rate ◽  
Fracture Energy ◽  
Elevated Temperatures ◽  
High Growth ◽  
High Growth Rate ◽  
Growth Speed ◽  
Crossover Effect ◽  
Fracture Properties ◽  
Fracture Parameters

This paper investigated the fracture properties of concrete in dry environments with different curing temperatures (5, 20, 40, and 60 °C). For each curing condition, the key fracture parameters of concrete were tested using wedge splitting specimens at five different ages (3, 7, 14, 28, and 60 d). The results show that in dry environments, the effective fracture toughness and fracture energy of concrete exposed to elevated temperatures increased at a relatively high growth rate at an early age. Nevertheless, the growth speed of effective fracture toughness and fracture energy decreased more quickly at elevated temperatures in the later stages. As a result, the concrete cured at higher temperature exhibited lower ultimate values of fracture parameters, and vice-versa. Namely, a temperature crossover effect was found in the effective fracture toughness and fracture energy of concrete under dry environments. Considering the early growth rate and ultimate values of fracture parameters, the optimum temperature suitable for concrete fracture properties development under dry condition was around 40 °C.

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