Advanced Materials Research Vols. 118-120

Abstract: There has been a growing interest in assessing the ongoing reliability of electronics and systems in order to predict failures and provide warning to avoid catastrophic failure. Methods based on prognostics and health management shows an enabling technology to assess the reliability of electronics and systems under its actual application conditions. However, many challenges in implementation of methods based on PHM still remain including: environmental and usage profiles for life-cycle loads, identification of failure mechanism, identification of failure PoF model, identification of parameters to be monitored, approaches to anomaly detection. These challenges were presented and discussed, and would be carried out by developing methodologies and techniques.

Abstract: The influence of the local sunken plate on ultimate strength is analyzed, and reliability calculation and sensitivity analysis expressions of the plate element are also given in this paper. Finally, taking a numerical example, the influence of each sunken factor on plate ultimate strength reliability is analyzed. The result indicates that the influence of sunken diameter and sunken depth on reliability is larger. The method that is given in this paper, it is a reference for reasonable maintenance of structure.

Abstract: With the purpose of researching how the parameters such as style, pitch and rod length of the attach member impact the overall crane, the variation of the strength and stiffness in attach member. The theory of nonlinear big displacement is adopted to model the overall crane. And the model was considered in several working conditions，then the trends of the stress, axial force and the displacement are shown by Graphics and data. From above, a better style of the attach member can be chosen and this method which is shortening the distance between tower centerline and outer wall lengthening the rod of attach member would be helpful to the attach member program in engineering.

Abstract: In this study, the bonding reliability of the COG devices was studied. A finite element analyses model was established to study the curing process of COG module. The equivalent stress of the different locations of the package structure and the change of the temperature distribution with time were studied. The heat transfer process and the conductive particle deformation process were displayed through the simulation. The results show that the curing process is the heat transformation and particle deformation process. The residual stress generated by the temperature difference between the curing temperature and the operated temperature. The results show that the maximum residual stress is in the most distorted places of the conductive particles. The maximum residual thermal stress was studied with different bump pitch (35μm 30μm 25μm and 20μm) and the size of the particles (5μm, 4μm and 3.5μm). It shows that for a certain size of the particles, the maximum residual thermal stress will decrease when the bump pitch decreases. For a certain bump pitch, the maximum residual thermal stress will decrease when the size of the particles decrease.

Abstract: Several life measures are defined in the literature. This paper deals with defining a service life measure for a component with lognormal life. It is proposed to set the service life at the inflection of the failure rate function. The service life defined in such a way is a function of the shape parameter. This implies that the shape parameter reflects the product quality. Based on the value of the shape parameter, the component quality can be classified and the component can have different quality improvement or maintenance strategy.

Abstract: Accelerated life testing can be operated in the designing process of a product to predict the lifetime of the product. The design of the product would be improved if the lifetime prediction value is not acceptable. This paper presents a method to predict lifetime of products based on proportional hazards-proportional odds model in accelerated life testing. Proportional hazards-proportional odds model makes proportional hazards model and proportional odds model special cases of it through transformation parameter. A testing system is established to process constant stress accelerated life testing for miniature bulbs under high stress levels and failure time data of the bulbs under each stress level are analyzed using proportional hazards-proportional odds model. Lifetime prediction of the miniature bulbs is presented finally.

Abstract: Both Al interconnects and flip-chip solder bumps were sensitive to high current. The failure mechanism of circuits interconnects would be more complicated if the current density in circuits was exceed the critical magnitudes of electromigration in both Al interconnects and solder bumps. The failure of circuit interconnects under different magnitudes of current density was studied and the interaction of electromigration in solder bumps and Al interconnects was discussed. The circuit interconnects of flip chip show three failure phenomena under high current density: voids in Al final metal, inter-diffusion of Al and SnPb, and melting of solder bumps. The voids in Al metal show the directional diffusion of Al atoms was mainly controlled by the electron wind fore. However the inter-diffusion of Al and SnPb demonstrated the electron wind force to Sn and Pb atoms would be ignored in contrast with chemical potential gradient or intrinsic stress. The flow of Sn and Pb atoms under high current density was in opposite direction with electron wind force and uniform with chemical potential gradient.

Abstract: Electroencephalogram (EEG) and event-related potential (ERP) were conducted, in order to research brain functions associated with the effect of design for car models. The results demonstrated enhanced alpha and beta power of EEG by looking at the favorite car model. The ERP powers were strongly blocked (reduced) by looking at the un-favorite car model. EEG/ERP could be the electrophysiological index for automobile modeling evaluations.

Abstract: Evaluating the health level of vehicles usually involves several factors and often needs to introduce subjective information. This paper presents an approach to combine several performance measures into a composite index for health evaluation. A mathematical method is proposed to estimate the overall performances of vehicles based on the observed performances under multiple measures or criteria. The approach is illustrated using a real-world example.

Abstract: With the qualities of smooth operation, high efficiency and small size, the planetary gear box was widely used in transmission field. In this paper, a 2-stage planetary gear box was studied. CAXA and Pro/E were used for modeling. The FEA analysis results were obtained by ANSYS, both the contact stress and the bending stress of the gear tooth root. The results showed that with the continuous action of cyclic loads, the excessive contact stress is the direct reason of the failure. Then, the system reliability evaluation was made, which can provide guidance for engineering practice.