Propagation of Bidens laevis : a native Asteraceae from freshwater wetlands to be used as ornamental plant

p.1-7

Phitotoxicity of Crhomium over Phaseolus vulgaris L.

p.75-80

Brócoli envasado en polietileno de baja densidad y policloruro de vinilo

p.191-198

Salpicadura y escurrimiento en un suelo argiudol vértico y su interacción con el tamaño de agregados superficiales

p.239-244

Evaluación del efecto de la fertilización con boro para híbridos de girasol en suelos haplustoles énticos de Gral. Pico, Departamento de Maracó, Prov. de La Pampa

p.45-49

Exposición natural y envejecimiento acelerado de polietilenos para invernaderos, en diferentes condiciones climáticas

p.221-228

Calibración y validación de un modelo de simulación de rendimiento de maní (Arachis hypogaea L.)

p.25-32

Naturaleza de la fertilización y calidad de hortalizas

p.123-134

Influencia del uso de la tierra sobre la erosión entre surcos en un argiudol típico de Argentina

p.333-340

Calibración del método de Bingham para trigo en el S.O. Bonaerense

p.191-198

Cinética de sobrevivencia de Rhizobium meliloti B - 36 sobre semilla preinoculada con diferentes adhesivos y coberturas

p.167-171

Nuevo inoculante líquido para semillas de soja (Glycine max)

p.127-132

Análisis de productividad y calidad comercial en plantas de rosa para corte injertadas sobre dos nuevos patrones

p.141-146

Optimization and finite element analysis for reliable electronic packaging

This paper demonstrates a modeling and design approach that couples computational mechanics techniques with numerical optimisation and statistical models for virtual prototyping and testing in different application areas concerning reliability of eletronic packages. The integrated software modules provide a design engineer in the electronic manufacturing sector with fast design and process solutions by optimizing key parameters and taking into account complexity of certain operational conditions. The integrated modeling framework is obtained by coupling the multi-phsyics finite element framework - PHYSICA - with the numerical optimisation tool - VisualDOC into a fully automated design tool for solutions of electronic packaging problems. Response Surface Modeling Methodolgy and Design of Experiments statistical tools plus numerical optimisaiton techniques are demonstrated as a part of the modeling framework. Two different problems are discussed and solved using the integrated numerical FEM-Optimisation tool. First, an example of thermal management of an electronic package on a board is illustrated. Location of the device is optimized to ensure reduced junction temperature and stress in the die subject to certain cooling air profile and other heat dissipating active components. In the second example thermo-mechanical simulations of solder creep deformations are presented to predict flip-chip reliability and subsequently used to optimise the life-time of solder interconnects under thermal cycling.

An integrated approach to flow, thermal and mechanical modeling of electronics devices

The future success of many electronics companies will depend to a large extent on their ability to initiate techniques that bring schedules, performance, tests, support, production, life-cycle-costs, reliability prediction and quality control into the earliest stages of the product creation process. Earlier papers have discussed the benefits of an integrated analysis environment for system-level thermal, stress and EMC prediction. This paper focuses on developments made to the stress analysis module and presents results obtained for an SMT resistor. Lifetime predictions are made using the Coffin-Manson equation. Comparison with the creep strain energy based models of Darveaux (1997) shows the shear strain based method to underestimate the solder joint life. Conclusions are also made about the capabilities of both approaches to predict the qualitative and quantitative impact of design changes.