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The reliability of 0.5 mm pitch, 32‐pin thin small outline package (TSOP) solder joints has been studied by experimental temperature cycling and a cost‐effective 3‐D non‐linear finite element analysis. Temperature cycling results have been presented as a Weibull distribution, and an acceleration factor has been established for predicting the failure rate at operating conditions. Thermal fatigue life of the corner solder joints has been estimated based on the calculated plastic strain, Coffin‐Manson law and isothermal fatigue data on solders. A correlation between the experimental and analytical results has also been made. Furthermore, failure analysis of the solder joints has been performed using scanning electron microscopy (SEM) and an optical method. Finally, a quantitative comparison between the Type‐I and Type‐II TSOP solder joints has been presented.

Alloy 42 and, similarly, Kovar were developed to provide metallic feed‐throughs from the interior of ceramic components to the exterior. The low coefficient of thermal expansion (CTE) of ceramic needs to be almost matched by the feed‐through metal to allow reliable hermetically sealed connections. For this purpose these alloys have served very well. However, because of its wide‐spread use for military applications, for which component hermeticity has been required, as well as because of the easier attachment of low‐CTE die to low‐CTE lead frames, Alloy 42 has found its way into plastic components with often disastrous results. When surface mount solder joints connect materials with different CTEs, global thermal expansion mismatches result. Also, if the materials to which the solder bonds have CTEs that differ from the CTE of solder, local thermal expansion mismatches result. These thermal expansion mismatches are the cause of most SM solder joint failures. Alloy 42 and Kovar not only cause significant global and local thermal expansion mismatches, but are inherently more difficult to solder because of the low solubility of nickel and iron, the main constituents of these alloys, in tin. Pull tests of solder joints show that under the best of circumstances a solder joint that includes an Alloy 42 or Kovar surface is only half as strong as one made to copper surfaces.

This paper presents a solder joint engineering reliability model — Solder Reliability Solutions** (SRS) — and its application to surface mount area‐array and chip‐scale assemblies. The model is validated by failure data from 33 accelerated thermal cycling tests, and test vehicles covering several generations of component, assembly and circuit board technologies and a variety of test conditions. The SRS model has been implemented as a PC‐based design‐for‐reliabilltytool that enables rapid assessment of assembly reliability in the early stages of product development.

As part of the portable product interconnects characterisation programme, the present investigation was conducted to determine the attachment integrity and long‐term reliability of Thin small Outline package (TSOP) solder joints. Accelerated thermal cycling combined with analytical modelling was used to evaluate the reliability for credit card sized DRAM memory cards. The measured solder joint fatigue lifetimes varied from 645 to 830 thermal cycles for TSOP‐II and I components, respectively. The modelling results corroborated the empirical findings. The solder joint thermal fatigue data were used to predict the card reliability under operating field conditions. The cards were found to be reliable for their intended use environment.

The purpose of present investigation is to analyze the in-mold electromagnetic stirring (M-EMS) process and the effect of stirrer frequency on fluid flow and solidification in a continuous casting billet caster mold.

A hybrid approach involving finite element and finite volume method has been used for the study. Finite element model is used to calculate time variable magnetic field, which is further coupled with fluid flow and solidification equations for magneto-hydrodynamic analysis with finite volume model.

Results show that though superheat given to steel before its entry into the mold is quickly removed, solid shell formation is delayed by the use of M-EMS. Final solid shell thickness, however, is slightly reduced. Increase in frequency is found to increase the magnetic flux density and tangential velocity of liquid steel and decrease in diameter of liquid core.

The work is of great industrial relevance. The model may be used to design industrial setup of in-mold electromagnetic stirrer and process could be analyzed and optimized numerically.

The paper evaluates the influence of M-EMS and its frequency on solidification and flow behavior in the continuous casting mold. The iso-surface temperatures from pouring temperature to liquidus temperature inside the mold have been shown. The findings may be useful for the steelmakers to reduce the defect in continuous casting.

A viscoplastic constitutive model, the Anand model, in which plasticity and creep are unified and described by the same set of flow and evolutionary relations, was applied to represent the inelastic deformation behavior for solder alloys. After conducting creep tests and constant strain rate tests, the material parameters for the Anand model of the Pb‐rich content solder 92.5Pb5Sn2.5Ag were determined from the experimental data using a nonlinear fitting method. The material parameters for 60Sn40Pb, 62Sn36Pb2Ag and 96.5Sn3.5Ag solders were fitted from the conventional model in the literature where plasticity and creep are artificially separated. Model simulations and verifications reveal that there is good agreement between the model predictions and experimental data. Some discussion on this unified model is also presented. This viscoplastic constitutive model for solder alloys possesses some advantages over the separated model. The achieved Anand model has been applied in finite element simulation of stress/strain responses in solder joints for chip component, thin quad flat pack and flip‐chip assembly. The simulation results are in good agreement with the results in the literature. It is concluded that the Anand model could be recommended as a useful material model for solder alloys and can be used in the finite element simulation of solder joint reliability in electronic packaging and surface mount technology.

The purpose of this paper is to develop a cost effective ball grid array (BGA) workcell for solder ball attachment.

This paper presents the construction of a low‐cost high‐efficiency automatic ball attachment workcell. In fact, it is an economical means of simultaneous placement of all solder balls on BGA substrates containing multiple BGA units as well as singulated substrates. Common industry problems such as the effect of static charges, the solder ball oxidation, the missing ball, the extra ball, the ball alignment, the deformed ball and, etc. will be addressed and critical issues affecting yield will also be discussed in this paper.

BGA is a popular integrated circuit packaging that is often applied in laptop computers and other handheld electronic devices for the provision of a high‐connection count in a relatively small area. However, the cost of a market available BGA solder ball attachment workcell is very expensive and the flexibility in fitting various customized process is usually low.

The developed workcell cost is about half of the market available machines with similar specifications; the yield achieved is within three sigma confidence interval with competitive output rate. The maintenance and troubleshooting are easy since the machine was developed by the in‐house engineering team.

The purpose of this paper is to analyze factors associated with post-traumatic stress disorder (PTSD) among elderly who live in a post-earthquake area.

This was a cross-sectional study involving 152 elder people who survived the disaster and were selected conveniently. The study was conducted in two worst-affected districts of Lombok Utara regency. PTSD was diagnosed using a modified version of the Clinician-Administered PTSD Scale version 5 (CAPS-5). The demographic data were assessed using a self-developed questionnaire consisting of 13 items. All data were analyzed by descriptive analysis, χ² test and binary logistic regression with p<0.05.

Out of the 152 elder people, 91 (59.9 percent) suffered PTSD. Intrusion symptoms were the most common symptoms experienced by the respondents (94.1 percent). The factors associated with the PTSD in the elderly after the earthquake were having chronic illnesses (OR=2.490; 95% CI=1.151–5.385), public health center utilization (OR=2.200; 95% CI=1.068–4.535) and occupational status before the disaster (OR=2.726; 95% CI=1.296–5.730). These findings highlight that individual factors and access to health care services remain an important aspect of stress identification among the elderly following the disaster event.

Elder people constitute a vulnerable group that is often forgotten and neglected during post-disaster recovery, though they have potentially higher psychosocial distress than younger age groups. This study was conducted to raise awareness about mental health problems suffered by the elderly.

This is the first study to apply CAPS-5 to assess PTSD among Indonesian elderly people following a natural disaster. This paper also provides insights that can be used by governments and other relevant parties to address PTSD problems suffered by many elderly people in a post-disaster area.

This purpose of the paper is to examine the multi-channel cyclone created at the Vilnius Gediminas Technical University (VGTU) Research Institute of Environmental Protection. The paper aims to predict the possible trajectories of solid particle motion in the cyclone with reference to the mechanical forces only.

The numerical calculations were performed on the basis of experimental results. The system of differential equations describing particle motion in the cyclone is analysed and numerically solved using Runge–Kutta–Fehlberg method. Research consists of three examples that illustrate the impact of particle density and velocity on collection and analyses the particle motion trajectories in the first and second channels of the cyclone.

Numerical calculations were performed according to the data from Vilnius Gediminas Technical University Research Institute of Environmental Protection. The particulate matter of wood ash and granite were used. The collection of solid particles of different size was examined when the air inflow velocity varies from 10 to 20 m/s. The possible motion trajectories of the solid particles are defined and the parameters of collected particles have been discussed.

The obtained results can be used for the analysis of air cleaning efficiency and particulate matter removal from air in a multi-channel cyclone.

The results lead us to improve the structure of the cyclone so as to effectively collect the solid particles of different size.

This paper presents the results obtained for the multi-channel cyclone created at the Vilnius Gediminas Technical University Research Institute of Environmental Protection.

This study aims to provide discussions of the numerical method and the bubbly flow characteristics of an annular bubble plume.

The bubbles, released from the annulus located at the bottom of the domain, rise owing to buoyant force. These released bubbles have diameters of 0.15–0.25 mm and satisfy the bubble flow rate of 4.1 mm³/s. The evolution of the three-dimensional annular bubble plume is numerically simulated using the semi-Lagrangian–Lagrangian (semi-L–L) approach. The approach is composed of a vortex-in-cell method for the liquid phase and a Lagrangian description of the gas phase.

First, a new phenomenon of fluid dynamics was discovered. The bubbly flow enters a transition state with the meandering motion of the bubble plume after the early stable stage. A vortex structure in the form of vortex rings is formed because of the inhomogeneous bubble distribution and the fluid-surface effects. The vortex structure of the flow deforms as three-dimensionality appears in the flow before the flow fully develops. Second, the superior abilities of the semi-L–L approach to analyze the vortex structure of the flow and supply physical details of bubble dynamics were demonstrated in this investigation.

The semi-L–L approach is applied to the simulation of the gas–liquid two-phase flows.