Modeling the SAC microstructure evolution under thermal, thermomechanical and electrical constraints

[no abstract

4D Microstructural Characterization of Electromigration and Thermal Aging Damage in Tin-Rich Solder Joints

abstract: As the microelectronics industry continues to decrease the size of solder joints, each joint will have to carry a greater current density, making atom diffusion due to current flow, electromigration (EM), a problem of ever-increasing severity. The rate of EM damage depends on current density, operating temperature, and the original microstructure of the solder joint, including void volume, grain orientation, and grain size. While numerous studies have investigated the post-mortem effects of EM and have tested a range of current densities and temperatures, none have been able to analyze how the same joint evolves from its initial to final microstructure. This thesis focuses on the study of EM, thermal aging, and thermal cycling in Sn-rich solder joints. Solder joints were either of controlled microstructure and orientation or had trace alloying element additions. Sn grain orientation has been linked to a solder joints’ susceptibility to EM damage, but the precise relationship between orientation and intermetallic (IMC) and void growth has not been deduced. In this research x-ray microtomography was used to nondestructively scan samples and generate 3D reconstructions of both surface and internal features such as interfaces, IMC particles, and voids within a solder joint. Combined with controlled fabrication techniques to create comparable samples and electron backscatter diffraction (EBSD) and energy-dispersive spectroscopy (EDS) analysis for grain orientation and composition analysis, this work shows how grain structure plays a critical role in EM damage and how it differs from damage accrued from thermal effects that occur simultaneously. Unique IMC growth and voiding behaviors are characterized and explained in relation to the solder microstructures that cause their formation and the possible IMC-suppression effects of trace alloying element addition are discussed.Dissertation/ThesisDoctoral Dissertation Materials Science and Engineering 201

Flows through s-shaped annular, inter-turbine diffusers

Inter-turbine diffusers or swan neck ducts (SND's) provide flow continuity between the H.P. and L.P. turbine, which with diffusing of the flow allow; greater stage efficiencies to be achieved as a consequence of reducing both the stage loading and flow coefficient of the L.P. turbine. This thesis presents an experimental and computational investigation into the local flow development and overall performance of two different severity diffusing annular sshaped ducts, with the same overall diffusion ratio of 1.5, in order to validate the CFD code M.E.F.P. The first less severe diffusing duct was used to investigate the effects of inlet swirl on the duct performance. It was found that at an optimum swirl angle of 15 degrees, the duct total pressure loss coefficient was approximately half the value at 0 or 30 degrees swirl. The second more severely diffusing duct had simple symmetrical aerofoil struts added, which simulated struts required in real inter-turbine diffusers to support inner shafts and supply vital engine services. The total pressure loss developed by the 30% shorter duct was 15% greater that of the longer duct, and when struts were added to the second duct the loss almost doubled. These increases were attributed to gradually worsening casing surface flow separations which also acted to reduce the overall static pressure recovery of the ducts as their losses increased. The computational investigations were made on the more severe duct with and without struts. The code, Moore's Elliptic Flow Solver (M.E.F.P) which used a mixing length model, predicted flow separation in the strutted duct case albeit in slightly the wrong position, however, it failed to predict any secondary flow for the unstrutted case and hence correlated worse with the measured results. This was also true of the results predicted by a version of Dawes BTOB3D

Bed of nails(B0N) - 100 microns pitch wafer level off-chip interconnects for microelectronic packaging applications

Master'sMASTER OF ENGINEERIN

CHARACTERIZATION OF ENGINEERED SURFACES

In the recent years there has been an increasing interest in manufacturing products where surface topography plays a functional role. These surfaces are called engineered surfaces and are used in a variety of industries like semi conductor, data storage, micro- optics, MEMS etc. Engineered products are designed, manufactured and inspected to meet a variety of specifications such as size, position, geometry and surface finish to control the physical, chemical, optical and electrical properties of the surface. As the manufacturing industry strive towards shrinking form factor resulting in miniaturization of surface features, measurement of such micro and nanometer scale surfaces is becoming more challenging. Great strides have been made in the area of instrumentation to capture surface data, but the area of algorithms and procedures to determine form, size and orientation information of surface features still lacks the advancement needed to support the characterization requirements of R&D and high volume manufacturing. This dissertation addresses the development of fast and intelligent surface scanning algorithms and methodologies for engineered surfaces to determine form, size and orientation of significant surface features. Object recognition techniques are used to identify the surface features and CMM type fitting algorithms are applied to calculate the dimensions of the features. Recipes can be created to automate the characterization and process multiple features simultaneously. The developed methodologies are integrated into a surface analysis toolbox developed in MATLAB environment. The deployment of the developed application on the web is demonstrated

Micromechanical Behaviour of Lead-free Solder Joints Developed for 3D-IC Packaging Applications

Ph.DDOCTOR OF PHILOSOPH

Heat dissipation performance of a high-brightness LED package assembly using high-thermal conductivity filler

2013-2014 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Index to 1983 NASA Tech Briefs, volume 8, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1983 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

NASA Tech Briefs, Fall 1983

Topics include: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology. New Product Ideas: A summary of selected Innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences