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Your search keyword '"Ribas, Morgana A."' showing total 23 results
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23 results on '"Ribas, Morgana A."'

1. The Interaction of 2 SOLDER PASTE ALLOYS with 5 Surface Finishes, Part 2: SAC 305 shows faster shear strength degradation than Innolot, while the surface finish has no effect

Author

Choudhury, Pritha, Ribas, Morgana, Fudala, John, and Holtzer, Mitch

Subjects
Metals, Degassing of metals, Alloys, Specialty metals industry, Business, Computers and office automation industries, Engineering and manufacturing industries, Business, international
Abstract

When a solder joint is exposed to cyclic stresses, thermally activated diffusion in the bulk solder; metallization and initial inter-metallic (IMC) may take place. The growth of the interfacial IMC [...]

Published
2021

2. The Interaction of 2 SOLDER PASTE ALLOYS with 5 Surface Finishes: For spread and wetting performance, certain finishes stand out

Author

Choudhury, Pritha, Ribas, Morgana, Fudala, John, and Holtzer, Mitch

Subjects
Metals, Industrial design, Degassing of metals, Alloys, Specialty metals industry, Business, Computers and office automation industries, Engineering and manufacturing industries, Business, international
Abstract

Electronic assemblers have myriad material and process choices to make, not limited to board materials, solder masks, laminate Tg's, components, surface finishes, assembly materials and design for manufacturing (DfM) process [...]

Published
2021

4. High-Reliability, Fourth-Generation LOW-TEMPERATURE SOLDER Alloys: Results of melting behavior, solder joint formation, tensile strength and high-temperature creep tests

Author

Ribas, Morgana, Kumar, Anil, Augustine, Prathap, Choudhury, Pritha, and Sarkar, Siuli

Subjects
Energy conservation -- Mechanical properties, Metals -- Mechanical properties, Degassing of metals -- Mechanical properties, Alloys -- Mechanical properties, Labor costs -- Mechanical properties, Specialty metals industry -- Mechanical properties, Business, Computers and office automation industries, Engineering and manufacturing industries, Business, international
Abstract

There has always been a latent interest in low-temperature solders, as they can 1) potentially reduce material cost by enabling use of cheaper PCBs and components due to the lower [...]

Published
2020

5. Patterning Nanoroads and Quantum Dots on Fluorinated Graphene

Author

Ribas, Morgana A., Singh, Abhishek K., Sorokin, Pavel B., and Yakobson, Boris I.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Using ab initio methods we have investigated the fluorination of graphene and find that different stoichiometric phases can be formed without a nucleation barrier, with the complete "2D-Teflon" CF phase being thermodynamically most stable. The fluorinated graphene is an insulator and turns out to be a perfect matrix-host for patterning nanoroads and quantum dots of pristine graphene. The electronic and magnetic properties of the nanoroads can be tuned by varying the edge orientation and width. The energy gaps between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO) of quantum dots are size-dependent and show a confinement typical of Dirac fermions. Furthermore, we study the effect of different basic coverage of F on graphene (with stoichiometries CF and C$_{4}$F) on the band gaps, and show the suitability of these materials to host quantum dots of graphene with unique electronic properties., Comment: 12 pages, 7 figures, 1 table

Published
2010
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11. iNEMI project on process development of BiSn-based low temperature solder pastes: Part III: Mechanical shock tests on POP BGA assemblies

Author

Fu, Haley, primary, Radhakrishnan, Jagadeesh, additional, Ribas, Morgana, additional, Aspandiar, Raiyo, additional, Byrd, Kevin, additional, Chen, Jimmy, additional, Cheng, Shunfeng, additional, Chen, Qin, additional, Coyle, Richard, additional, Feng, Sophia, additional, Krmpotich, Mark, additional, Mokler, Scott, additional, Sandy-Smith, Brook, additional, Tang, Kok Kwan, additional, Wu, Greg, additional, Zhang, Anny, additional, and Zhen, Wilson, additional

Published
2018
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12. iNEMI project on process development of BISN-based low temperature solder pastes — Part II: Characterization of mixed alloy BGA solder joints

Author

Fu, Haley, primary, Aspandiar, Raiyo, additional, Chen, Jimmy, additional, Cheng, Shunfeng, additional, Chen, Qin, additional, Coyle, Richard, additional, Feng, Sophia, additional, Hardin, Bill, additional, Krmpotich, Mark, additional, Mokler, Scott, additional, Radhakrishnan, Jagadeesh, additional, Ribas, Morgana, additional, Sandy-Smith, Brook, additional, Tang, Kok Kwan, additional, Wu, Greg, additional, Zhang, Anny, additional, and Zhen, Wilson, additional

Published
2018
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15. Nanotube nucleation versus carbon-catalyst adhesion–Probed by molecular dynamics simulations.

Author

Ribas, Morgana A., Feng Ding, Balbuena, Perla B., and Yakobson, Boris I.

Subjects
*NANOTUBES, *MOLECULAR dynamics, *NUCLEATION, *SIMULATION methods & models, *SOLUTION (Chemistry), *SOLID solutions
Abstract

Catalytic nucleation of carbon nanotubes (CNTs) remains a challenge for the theory: Which factors and forces decide if the gathering sp2-network of atoms will adhere to the catalyst particle and fully cover it or the graphitic cap will liberate itself to extend into a hollow filament? This intimate mechanism cannot be seen in experiment, yet it can be investigated through comprehensive molecular dynamics. We systematically vary the adhesion strength (Wad) of the graphitic cap to the catalyst and temperature T (and C diffusion rate). Observations allow us to build a statistically representative map of CNT nucleation and define the conditions for growth or metal encapsulation in a fullerene-shell (catalyst poisoning). It shows clearly that weak Wad, sufficient thermal kinetic energy (high T) or fast C diffusion favor the CNT nucleation. In particular, below 600 K carbon-diffusion on the catalyst surface limits the growth, but at higher T it fully depends on cap lift-off. Informed choice of parameters allowed us to obtain the longest simulated nanotube structures. The study reveals a means of designing the catalyst for better CNT synthesis, potentially at desirably low temperatures. [ABSTRACT FROM AUTHOR]

Published
2009
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16. Wafer level CSP with ultra-high thermal reliability lead-free alloys

Author

Ribas, Morgana, primary, Lim, Garian, additional, Bumagat, Rommel T., additional, Kumar, Anil, additional, Kosuri, Divya, additional, Augustine, Prathap, additional, Choudhury, Pritha, additional, Rangaraju, Raghu R., additional, Telu, Suresh, additional, Sarkar, Siuli, additional, Sobczak, Martin, additional, and Singh, Bawa, additional

Published
2015
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23. H-Spillover through the Catalyst Saturation: An Ab InitioThermodynamics Study

Author

Singh, Abhishek K., Ribas, Morgana A., and Yakobson, Boris I.

Abstract

The spillover phenomenon, which essentially involves transfer of H from a metal catalyst to a graphitic receptor, has been considered promising for efficient hydrogen storage. An open question about the spillover mechanism is how a H atom binds to graphene instead of forming the thermodynamically preferred H2. Using ab initiocalculations, we show that the catalyst saturation provides a way to the adsorption of hydrogen on the receptor by increasing the H chemical potential to a spillover favorable range. Although it is energetically unfavorable for the spillover to occur on a pristine graphene surface, presence of a phase of hydrogenated graphene facilitates the spillover by significantly improving the C−H binding. We show that thermodynamic spillover can occur, both from the free-standing and from the receptor-supported clusters. Further, the computed energy barrier of the motion of a H from the catalyst to the hydrogenated graphene is small (0.7 eV) and can be overcome at operational temperatures.

Published
2009
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