Predictive Failure Analysis of Solder Joints with Simultaneous High Speed EBSD and EDS

2018 ◽  
Author(s):  
J. Lindsay ◽  
P. Trimby ◽  
J. Goulden ◽  
S. McCracken ◽  
R. Andrews
Keyword(s):  
High Speed ◽  
Solder Joints ◽  
Phase Distribution ◽  
Bond Failure ◽  
Microstructural Parameters ◽  
Snpb Solder ◽  
Grain Orientations ◽  
Accelerated Thermal Cycling ◽  
The Relationship ◽  
Opening Up

Abstract The results presented here show how high-speed simultaneous EBSD and EDS can be used to characterize the essential microstructural parameters in SnPb solder joints with high resolution and precision. Analyses of both intact and failed solder joints have been carried out. Regions of strain localization that are not apparent from the Sn and Pb phase distribution are identified in the intact bond, providing key insights into the mechanism of potential bond failure. In addition, EBSD provides a wealth of quantitative detail such as the relationship between parent Sn grain orientations and Pb coarsening, the morphology and distribution of IMCs on a sub-micron scale and accurate grain size information for all phases within the joint. Such analyses enable a better understanding of the microstructural developments leading up to failure, opening up the possibility of improved accelerated thermal cycling (ATC) testing and better quality control.

Measurement of impact toughness of eutectic SnPb and SnAgCu solder joints in ball grid array by mini-impact tester

2008 ◽  
Vol 23 (5) ◽  
pp. 1482-1487 ◽  
Author(s):  
Yuhuan Xu ◽  
Shengquan Ou ◽  
K.N. Tu ◽  
Kejun Zeng ◽  
Rajiv Dunne
Keyword(s):  
Impact Toughness ◽  
High Speed ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Snagcu Solder ◽  
Snpb Solder ◽  
Impact Tester ◽  
Pull Tests ◽  
The Impact ◽  
Eutectic Snpb

The most frequent cause of failure for wireless, handheld, and portable consumer electronic products is an accidental drop to the ground. The impact may cause interfacial fracture of ball-grid-array solder joints. Existing metrology, such as ball shear and ball pull tests, cannot characterize the impact-induced high speed fracture failure. In this study, a mini-impact tester was utilized to measure the impact toughness and to characterize the impact reliability of both eutectic SnPb and SnAgCu solder joints. The annealing effect at 150 °C on the impact toughness was investigated, and the fractured surfaces were examined. The impact toughness of SnAgCu solder joints with the plating of electroless Ni/immersion Au (ENIG) became worse after annealing, decreasing from 10 or 11 mJ to 7 mJ. On the other hand, an improvement of the impact toughness of eutectic SnPb solder joints with ENIG was recorded after annealing, increasing from 6 or 10 to 15 mJ. Annealing has softened the bulk SnPb solder so that more plastic deformation can occur to absorb the impact energy.

A Note on the Publication History of John Polidori's The Vampyre

2020 ◽  
Vol 22 (3) ◽  
pp. 330-343
Author(s):  
Fabio Camilletti
Keyword(s):  
Textual Criticism ◽  
Active Role ◽  
Publication History ◽  
History Of ◽  
The Relationship ◽  
Opening Up

It is generally assumed that The Vampyre was published against John Polidori's will. This article brings evidence to support that he played, in fact, an active role in the publication of his tale, perhaps as a response to Frankenstein. In particular, by making use of the tools of textual criticism, it demonstrates how the ‘Extract of a Letter from Geneva’ accompanying The Vampyre in The New Monthly Magazine and in volume editions could not be written without having access to Polidori's Diary. Furthermore, it hypothesizes that the composition of The Vampyre, traditionally located in Geneva in the course of summer 1816, can be postdated to 1818, opening up new possibilities for reading the tale in the context of the relationship between Polidori, Byron, and the Shelleys.

Researching (with) Major Food Retailers

2015 ◽  
Vol 15 (3) ◽  
pp. 33-39 ◽  
Author(s):  
David Evans
Keyword(s):  
Food Systems ◽  
Academic Research ◽  
Social Scientists ◽  
Major Food ◽  
Food Retailers ◽  
Food Retailer ◽  
The One ◽  
The Uk ◽  
The Relationship ◽  
Opening Up

This paper considers the relationship between social science and the food industry, and it suggests that collaboration can be intellectually productive and morally rewarding. It explores the middle ground that exists between paid consultancy models of collaboration on the one hand and a principled stance of nonengagement on the other. Drawing on recent experiences of researching with a major food retailer in the UK, I discuss the ways in which collaborating with retailers can open up opportunities for accessing data that might not otherwise be available to social scientists. Additionally, I put forward the argument that researchers with an interest in the sustainability—ecological or otherwise—of food systems, especially those of a critical persuasion, ought to be empirically engaging with food businesses. I suggest that this is important in terms of generating better understandings of the objectionable arrangements that they seek to critique, and in terms of opening up conduits through which to affect positive changes. Cutting across these points is the claim that while resistance to commercial engagement might be misguided, it is nevertheless important to acknowledge the power-geometries of collaboration and to find ways of leveling and/or leveraging them. To conclude, I suggest that universities have an important institutional role to play in defining the terms of engagement as well as maintaining the boundaries between scholarship and consultancy—a line that can otherwise become quite fuzzy when the worlds of commerce and academic research collide.

scholarly journals Research on the Ignition Height and Reaction Flame Temperature of PTFE/Al/Si/CuO with Different Mass Ratios of PTFE/Si

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3464
Author(s):  
Xuan Zou ◽  
Jingyuan Zhou ◽  
Xianwen Ran ◽  
Yiting Wu ◽  
Ping Liu ◽  
...  
Keyword(s):  
Energy Release ◽  
High Speed ◽  
Flame Temperature ◽  
Sintering Process ◽  
Release Process ◽  
Reactive Material ◽  
Temperature Changes ◽  
Release Capacity ◽  
Mass Ratios ◽  
The Relationship

Recent studies have shown that the energy release capacity of Polytetrafluoroethylene (PTFE)/Al with Si, and CuO, respectively, is higher than that of PTFE/Al. PTFE/Al/Si/CuO reactive materials with four proportions of PTFE/Si were designed by the molding–sintering process to study the influence of different PTFE/Si mass ratios on energy release. A drop hammer was selected for igniting the specimens, and the high-speed camera and spectrometer systems were used to record the energy release process and the flame spectrum, respectively. The ignition height of the reactive material was obtained by fitting the relationship between the flame duration and the drop height. It was found that the ignition height of PTFE/Al/Si/CuO containing 20% PTFE/Si is 48.27 cm, which is the lowest compared to the ignition height of other Si/PTFE ratios of PTFE/Al/Si/CuO; the flame temperature was calculated from the flame spectrum. It was found that flame temperature changes little for the same reactive material at different drop heights. Compared with the flame temperature of PTFE/Al/Si/CuO with four mass ratios, it was found that the flame temperature of PTFE/Al/Si/CuO with 20% PTFE/Si is the highest, which is 2589 K. The results show that PTFE/Al/Si/CuO containing 20% PTFE/Si is easier to be ignited and has a stronger temperature destruction effect.

scholarly journals Diffraction Efficiency Characteristics for MEMS-Based Phase-Only Spatial Light Modulator with Nonlinear Phase Distribution

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 62
Author(s):  
Remington S. Ketchum ◽  
Pierre-Alexandre Blanche
Keyword(s):  
Diffraction Efficiency ◽  
High Speed ◽  
Phase Distribution ◽  
Complex Structure ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Micro Electro Mechanical Systems ◽  
Light Modulators ◽  
Nonlinear Phase ◽  
Liquid Crystal On Silicon

Micro-electro mechanical systems (MEMS)-based phase-only spatial light modulators (PLMs) have the potential to overcome the limited speed of liquid crystal on silicon (LCoS) spatial light modulators (SLMs) and operate at speeds faster than 10 kHz. This expands the practicality of PLMs to several applications, including communications, sensing, and high-speed displays. The complex structure and fabrication requirements for large, 2D MEMS arrays with vertical actuation have kept MEMS-based PLMs out of the market in favor of LCoS SLMs. Recently, Texas Instruments has adapted its existing DMD technology for fabricating MEMS-based PLMs. Here, we characterize the diffraction efficiency for one of these PLMs and examine the effect of a nonlinear distribution of addressable phase states across a range of wavelengths and illumination angles.

scholarly journals The Impact of Lipid Handling and Phase Distribution on the Acoustic Behavior of Microbubbles

Pharmaceutics ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 119
Author(s):  
Simone A.G. Langeveld ◽  
Inés Beekers ◽  
Gonzalo Collado-Lara ◽  
Antonius F. W. van der Steen ◽  
Nico de Jong ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Molecular Imaging ◽  
High Speed ◽  
Phase Distribution ◽  
Direct Method ◽  
Ultrasound Contrast Agents ◽  
Lipid Phase ◽  
Acoustic Behavior ◽  
Ultrasound Molecular Imaging ◽  
The Impact

Phospholipid-coated microbubbles are ultrasound contrast agents that can be employed for ultrasound molecular imaging and drug delivery. For safe and effective implementation, microbubbles must respond uniformly and predictably to ultrasound. Therefore, we investigated how lipid handling and phase distribution affected the variability in the acoustic behavior of microbubbles. Cholesterol was used to modify the lateral molecular packing of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)-based microbubbles. To assess the effect of lipid handling, microbubbles were produced by a direct method, i.e., lipids directly dispersed in an aqueous medium or indirect method, i.e., lipids first dissolved in an organic solvent. The lipid phase and ligand distribution in the microbubble coating were investigated using confocal microscopy, and the acoustic response was recorded with the Brandaris 128 ultra-high-speed camera. In microbubbles with 12 mol% cholesterol, the lipids were miscible and all in the same phase, which resulted in more buckle formation, lower shell elasticity and higher shell viscosity. Indirect DSPC microbubbles had a more uniform response to ultrasound than direct DSPC and indirect DSPC-cholesterol microbubbles. The difference in lipid handling between direct and indirect DSPC microbubbles significantly affected the acoustic behavior. Indirect DSPC microbubbles are the most promising candidate for ultrasound molecular imaging and drug delivery applications.

Roller–rail parameters on the transverse vibration characteristics of super-high-speed elevators

2019 ◽  
Vol 43 (4) ◽  
pp. 535-543 ◽  
Author(s):  
Shunxin Cao ◽  
Ruijun Zhang ◽  
Shuohua Zhang ◽  
Shuai Qiao ◽  
Dongsheng Cong ◽  
...  
Keyword(s):  
High Speed ◽  
Relative Displacement ◽  
Guide Rail ◽  
Coupled Vibration ◽  
Vibration Acceleration ◽  
Vibration Model ◽  
Vibration Problems ◽  
Equivalent Method ◽  
Relationship Of ◽  
The Relationship

Interaction and wear between wheel and rail become increasingly serious with the increase in elevator speed and load. Uneven roller surface, eccentricity of rollers, and the looseness of rail brackets result in serious vibration problems of high-speed and super-high-speed elevators. Therefore, the forced vibration differential equation representing elevator guide rails is established based on Bernoulli–Euler theory, and the vibration equation of the elevator guide shoes and the car is constructed using the Darren Bell principle. Then, the coupled vibration model of guide rail, guide shoes, and car can be obtained using the relationship of force and relative displacement among these components. The roller–rail parameters are introduced into the established coupled vibration model using the model equivalent method. Then, the influence of roller–rail parameters on the horizontal vibration of super-high-speed elevator cars is investigated. Roller eccentricity and the vibration acceleration of the car present a linear correlation, with the amplitude of the car vibration acceleration increasing with the eccentricity of the roller. A nonlinear relationship exists between the surface roughness of the roller and the vibration acceleration of the car. Increased continuous loosening of the guide rail results in severe vibration of the car at the loose position of the support.

Climate change in the Cameroonian press: An analysis of its representations

2020 ◽  
pp. 096366252097601
Author(s):  
Nicole Kay ◽  
Sandrine Gaymard
Keyword(s):  
Climate Change ◽  
Media Coverage ◽  
Psychological Distance ◽  
Environmental Issue ◽  
Social Psychological ◽  
Global Environmental Issue ◽  
Global Environmental ◽  
The World ◽  
The Relationship ◽  
Opening Up

Climate change is a global environmental issue and its outcome will affect societies around the world. In recent years, we have seen a growing literature on media coverage of climate change, but, to date, no study has assessed the situation in Cameroon, although it is considered to be one of the world’s most affected and vulnerable regions. This study attempted to address this deficit by analysing how climate change is represented in the Cameroonian media. A similarity analysis was performed on three newspapers published in 2013–2016. Results showed that climate coverage focused on politics and international involvement. It seems disconnected from local realities, potentially opening up a spatial and social psychological distance. The relationship between the representation of climate change and that of poverty is an area for further exploration.

Sign in / Sign up

Export Citation Format

Share Document