Mechanical Behavior of Flip-Chip Encapsulants

1990 ◽  
Vol 112 (4) ◽  
pp. 327-332 ◽  
Author(s):  
E. Suhir ◽  
J. M. Segelken
Keyword(s):  
Mechanical Behavior ◽  
Flip Chip ◽  
Calculated Data ◽  
Chip Design ◽  
Package Design ◽  
Silicone Gels ◽  
Low Modulus ◽  
Stress Models ◽  
Final Selection ◽  
Selection Of

Requirements for the mechanical properties of the encapsulation material in a flip-chip design to prevent the solder and the encapsulation material itself from failure are presented on the basis of the developed analytical stress models, enabling one to predict the stresses caused by the expansion (contraction) mismatch of these materials. We evaluate and discuss the mechanical behavior of encapsulants for two encapsulation technologies: 1) encapsulant fills in the entire underchip space (silicone gels, epoxies); 2) encapsulant conformably coats the underchip surfaces (polyxylylene, polyimide). The calculations are carried out for an Advanced VLSI Package Design. The calculated data have indicated that low modulus silicone gel results in the lowest stresses. Polyxylylene should be considered as the second preference. Polyimide is also acceptable. Epoxies, however, could result in significant stresses in solder joints and therefore are less attractive. The final selection of the most feasible encapsulant should be done, of course, with consideration of all the electrical, chemical, and technological requirements.

Application of an Epoxy Cap in a Flip-Chip Package Design

1989 ◽  
Vol 111 (1) ◽  
pp. 16-20 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Thermal Expansion ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Preliminary Test ◽  
Elastic Stability ◽  
Thermally Induced ◽  
Package Design ◽  
Silicone Gels ◽  
Low Modulus ◽  
Supporting Frame

In order to combine the merits of epoxies, which provide good environmental and mechanical protection, and the merits of silicone gels, resulting in low stresses, one can use an encapsulation version, where a low modulus gel is utilized as a major encapsulant, while epoxy is applied as a protecting cap. Such an encapsulation version is currently under consideration, parallel with a metal cap version, for the Advanced VLSI package design which is being developed at AT&T Bell Laboratories. We recommend that the coefficient of thermal expansion for the epoxy be somewhat smaller than the coefficient of thermal expansion for the supporting frame. In this case the thermally induced displacements would result in a desirable tightness in the cap/frame interface. This paper is aimed at the assessment of stresses, which could arise in the supporting frame and in the epoxy cap at low temperatures. Also, the elastic stability of the cap, subjected to compression, is evaluated. The calculations were executed for the Advanced VLSI package design and for a Solder Test Vehicle (STV), which is currently used to obtain preliminary information regarding the performance of the candidate encapsulants. It is concluded that in order to avoid buckling of the cap, the latter should not be thinner than 15 mils (0.40 mm) in the case of VLSI package design and than 17.5 mils (0.45 mm) in the case of STV. At the same time, the thickness of the cap should not be greater than necessary, both for smaller stresses in the cap and for sufficient undercap space, required for wirebond encapsulation. The obtained formulas enable one to evaluate the actual and the buckling stresses. Preliminary test data, obtained by using STV samples, confirmed the feasibility of the application of an epoxy cap in a flip-chip package design.

Analysis and Optimization of the Input/Output Fiber Configuration in a Laser Package Design

1995 ◽  
Vol 117 (4) ◽  
pp. 261-265 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Small Angle ◽  
Allowable Stress ◽  
Input Output ◽  
Transverse Axis ◽  
Thermally Induced ◽  
Package Design ◽  
Induced Stresses ◽  
Straight Fiber ◽  
Final Selection ◽  
Selection Of

The mechanical and thermally induced stresses in the input/output (I/O) fiber in a laser package design are evaluated for different fiber configurations. It is shown that, if the fiber experiences bending deformations, the mechanical stresses can be minimized by applying a proper end off-set. It is found also that, if the optical device can be rotated around the transverse axis by a small angle, this rotation can be effectively used for minimizing the stresses. The smallest fiber span can be achieved, if necessary, by making the fiber straight. In this case the fiber should be short enough to avoid buckling under the action of the compressive stress. We suggest that such a configuration be employed when the appropriate rotation of the device is possible, fiber ends can be easily aligned, and the support structures are strong enough to withstand the elevated thermal force from the compressed fiber. Although the results of the performed analysis can provide guidance for optimizing the I/O fiber configuration, the final selection of such a configuration can be made only after the allowable stress and the achievable end alignment (in the case of straight fiber) are established experimentally.

Measurements of the Cape Astrometric Survey of the Southern Hemisphere

1978 ◽  
Vol 48 ◽  
pp. 515-521
Author(s):  
W. Nicholson
Keyword(s):  
Southern Hemisphere ◽  
Automatic Measuring ◽  
Measuring Machine ◽  
Final Selection ◽  
Selection Of

SummaryA routine has been developed for the processing of the 5820 plates of the survey. The plates are measured on the automatic measuring machine, GALAXY, and the measures are subsequently processed by computer, to edit and then refer them to the SAO catalogue. A start has been made on measuring the plates, but the final selection of stars to be made is still a matter for discussion.

scholarly journals Recruitment of Employees—Assumptions of the Risk Model

Risks ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 55
Author(s):  
Halina Sobocka-Szczapa
Keyword(s):  
Risk Model ◽  
Model Identification ◽  
Added Value ◽  
Competitive Advantages ◽  
Recruitment Process ◽  
Process Risk ◽  
Model Formation ◽  
Risk Determinants ◽  
Final Selection ◽  
Selection Of

The aim of this article is to present the risk model premises related to worker recruitment. Recruitment affects the final selection of workers, whose activities contribute to corporate competitive advantages. Hiring unfavorable workers can influence the results produced by an organization. This risk mostly affects situations when searching for workers via the external labor market, although it can also affect internal recruitment. Therefore, it is necessary to attempt to identify recruitment risk determinants and classify their meaning in such processes. Model formation has both theoretical and intuitive characteristics. Model dependencies and their characteristics are identified in this paper. We attempted to assess the usability of the risk model for economic praxis. The analyses and results provide a model identification of dependencies between the factors determining a workers recruitment process and the risk which is caused by this process (employing inadequate workers who do not meet the employer’s expectations). The identification of worker recruitment process determinants should allow for practically reducing the risk of employing an inadequate worker and contribute to the reduction in unfavorable recruitment processes. The added value of this publication is the complex identification of recruitment process risk determinants and dependency formulations in a model form.

scholarly journals Sensor, Signal, and Imaging Informatics

2017 ◽  
Vol 26 (01) ◽  
pp. 120-124
Author(s):  
W. Hsu ◽  
S. Park ◽  
Charles Kahn
Keyword(s):  
Medical Informatics ◽  
Scientific Work ◽  
Imaging Informatics ◽  
Sensor Signal ◽  
Imaging Data ◽  
Extensive Search ◽  
Challenges And Opportunities ◽  
Final Selection ◽  
Selection Of

Summary Objective: To summarize significant contributions to sensor, signal, and imaging informatics published in 2016. Methods: We conducted an extensive search using PubMed® and Web of Science® to identify the scientific contributions published in 2016 that addressed sensors, signals, and imaging in medical informatics. The three section editors selected 15 candidate best papers by consensus. Each candidate article was reviewed by the section editors and at least two other external reviewers. The final selection of the six best papers was conducted by the editorial board of the Yearbook. Results: The selected papers of 2016 demonstrate the important scientific advances in management and analysis of sensor, signal, and imaging information. Conclusion: The growing volume of signal and imaging data provides exciting new challenges and opportunities for research in medical informatics. Evolving technologies provide faster and more effective approaches for pattern recognition and diagnostic evaluation. The papers selected here offer a small glimpse of the high-quality scientific work published in 2016 in the domain of sensor, signal, and imaging informatics.

scholarly journals Pre-selection of apple seedlings for partial powdery mildew (Podosphaera leucotricha Ell. et Ev. /Salm./) resistance

2011 ◽  
Vol 50 (No. 2) ◽  
pp. 65-69 ◽  
Author(s):  
J. Blažek
Keyword(s):  
Powdery Mildew ◽  
First Year ◽  
Podosphaera Leucotricha ◽  
Green House ◽  
Healthy State ◽  
The Mean ◽  
Resistant Genotypes ◽  
Different Levels ◽  
Final Selection ◽  
Selection Of

Incidences of powdery mildew were repeatedly evaluated for two years on 1 420 young seedlings of 20 progenies (of different levels of mildew susceptibility) in a green house, and then for 10 years on 642 seedlings in an orchard. Part of the seedlings in the orchard were pre-selected for the characteristic and others not. Except for the first scoring done in the first year, there was no correlation between mildew incidence on individual seedlings in the green house and their mean performance in the orchard. The seedlings with scores above 6 (resistant or tolerant) at the first stage of evaluation in the green house, however, yielded four times more desirable seedlings after final selection in the orchard than the mean of the total. The progenies that had a better healthy state as a whole yielded more partially resistant genotypes than those with low mean scores. Therefore, the progenies that most rapidly develop infestation on the whole lot should be discarded, whereas those that retain a healthy state longer should be subjected to individual selection according to the previous item.

scholarly journals Domains and Measurements of Healthy Aging in Epidemiological Studies: A Review

2018 ◽  
Vol 59 (4) ◽  
pp. e294-e310 ◽  
Author(s):  
Wentian Lu ◽  
Hynek Pikhart ◽  
Amanda Sacker
Keyword(s):  
Healthy Aging ◽  
Well Being ◽  
Epidemiological Studies ◽  
Health Security ◽  
Health Indices ◽  
Security Questions ◽  
Design And Methods ◽  
State Examination ◽  
Final Selection ◽  
Selection Of

Abstract Purpose of the Study Few studies have recommended the essential domains of healthy aging and their relevant measurement to assess healthy aging comprehensively. This review is to fill the gap, by conducting a literature review of domains and measures of healthy aging in epidemiological studies. Design and Methods A literature search was conducted up to March 31, 2017, supplemented by a search of references in all relevant articles in English. We made a final selection of 50 studies across 23 countries or regions. Results Nineteen studies applied Rowe and Kahn’s three standards to assess healthy aging. Thirty-seven studies measured physical capabilities mainly by (instrumental) activities of daily living. Cognitive functions were included in 33 studies. Nineteen of them applied Mini-Mental State Examination (MMSE). Twenty-six studies considered metabolic and physiological health, but they mainly asked the self-reported absence of diseases. Twenty-four studies assessed psychological well-being by employing diverse scales. Questions about participation in social activities were mainly asked to measure social well-being in 22 studies. Sixteen studies considered individuals’ general health status, which was mainly measured by self-rated health. Security questions were asked in five studies. Health behaviors were taken into account by three studies. Fifteen studies either applied SF-12/36 or developed health indices to assess healthy aging. Implications This review summarizes detailed scales or methods that have been used to assess healthy aging in previous epidemiological studies. It also discusses and recommends the essential domains of healthy aging, and the relevant instruments for further epidemiological research to use in the assessment of healthy aging.

scholarly journals Methodical basis of social security measurement of the state

2020 ◽  
pp. 56-62
Author(s):  
Oleh Dzoba ◽  
Nataliia Stavnycha
Keyword(s):  
Social Security ◽  
Social Protection ◽  
Calculated Data ◽  
The State ◽  
Security Assessment ◽  
The Social ◽  
Methodical Basis ◽  
Definition Of ◽  
Selection Of ◽  
Integral Indicator

Summary the article has analyzed the existing scientific and methodological approaches to assessing the level of social security of the state. It was revealed that they differ because: scientists include various components that form social security; they use various indicators and calculation methods; have various aspects of both generalization and practical direction. It was revealed that most often the components of social security include: safety of life, health, social protection and aspects of social and labor relations. The methods that are most often used in calculating the level of social security were considered. It was proved that in assessment, the selection of indicators that pose a threat, is the difficult task. It was revealed that there is no legally approved methodology for assessing the social security of the state. The use of various social security assessment methodologies was analyzed. Emphasis was placed on the selection of indicators used in these techniques. It was concluded that for assessing the social security of the state, an integral indicator is used most often. At the same time, scientists prefer their own set of indicators. The author’s definition of «social security» was presented, which allowed the formation of four components of the state’s social security (life, poverty, health and education). It was established that the choice of indicators for assessing the social security of the state should cover a retrospective period and should be based on both reporting and calculated data. A hierarchical model of an integral indicator of state social security was proposed. There was defined a set of indicators for each of proposed component. The following algorithm has been proposed for assessing the integral indicator of state social security: the formation of the components of social security and the definition of indicative indicators for each of the components; formation of a database; determination of an integral indicator; determining the influence of each component on the change in the integral indicator; interpretation of indicators; determining the sustainability of hazardous trends.

A Network-Flow-Based RDL Routing Algorithmz for Flip-Chip Design

2007 ◽  
Vol 26 (8) ◽  
pp. 1417-1429 ◽  
Author(s):  
Jia-Wei Fang ◽  
I-Jye Lin ◽  
Yao-Wen Chang ◽  
Jyh-Herng Wang
Keyword(s):  
Network Flow ◽  
Flip Chip ◽  
Chip Design
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