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.

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.

Predicted Thermal Stresses in a Circular Assembly With Identical Adherends and With Application to a Holographic Memory Package Design

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
E. Suhir ◽  
C. Gu ◽  
L. Cao
Keyword(s):  
Elevated Temperature ◽  
Thermal Stresses ◽  
Memory Systems ◽  
Stress Model ◽  
Adhesively Bonded ◽  
Holographic Memory ◽  
Thermally Induced ◽  
Package Design ◽  
Induced Stresses ◽  
Lower Temperature

A simple, easy-to-apply and physically meaningful analytical (“mathematical”) stress model is developed for the prediction of the thermally induced stresses in a circular adhesively bonded assembly with identical adherends. The assembly is fabricated at an elevated temperature and is subsequently cooled down to a lower temperature. The developed model can be helpful for stress-strain analyses and physical design of electronic and photonic assemblies of the type in question, and particularly those employed in holographic memory systems.

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.

Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces

1972 ◽  
Vol 30 ◽  
pp. 524-525
Author(s):  
C. S. Giggins ◽  
J. K. Tien ◽  
B. H. Kear ◽  
F. S. Pettit
Keyword(s):  
Electron Microscopy ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Substrate Surface ◽  
Morphological Features ◽  
Thermally Induced ◽  
Oxide Spallation ◽  
Oxidation Resistant ◽  
Induced Stresses ◽  
Substrate Surfaces

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).

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.

Heat Transfer and Thermal Stress Analysis of an Optoelectronic Package

1991 ◽  
Vol 113 (3) ◽  
pp. 258-262 ◽  
Author(s):  
J. G. Stack ◽  
M. S. Acarlar
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Power Dissipation ◽  
Point Of View ◽  
Optical Data ◽  
Data Link ◽  
Element Analysis ◽  
Thermally Induced ◽  
Temperature Changes ◽  
Induced Stresses

The reliability and life of an Optical Data Link transmitter are inversely related to the temperature of the LED. It is therefore critical to have efficient packaging from the point of view of thermal management. For the ODL® 200H devices, it is also necessary to ensure that all package seals remain hermetic throughout the stringent military temperature range requirements of −65 to +150°C. For these devices, finite element analysis was used to study both the thermal paths due to LED power dissipation and the thermally induced stresses in the hermetic joints due to ambient temperature changes

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.

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.

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