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This research aims on investigation the principles of Enhancement of Employee Enthusiasm (EEE) in mining industry. The methodology of study is through structural equation modeling to explain the relationship of each variable. Sampling through online based survey was conducted and analyzed 242 responses from workers of mining industry of Mongolia. The result shows the job satisfaction(JS), leadership...
This paper optimized the inventory of a multilevel distribution network with intermittent lead time extension resulting from disruptive transportation infrastructure damage because of regional weather and non-stationary demands. We proposed a hierarchical solution framework of a centralized inventory control policy to tackle with intermittent lead time fluctuation and demand fluctuation, leading to...
Vehicular ad hoc networks (VANETs) allow vehicles to generate and broadcast messages to inform nearby vehicles about road conditions. We propose a multi-hop announcement scheme for VANETs which supports message broadcasting and forwarding. In this scheme, we propose two algorithms to evaluate the reliability of messages and aggregate the reputation scores respectively. The major principle of the reliability...
The effect of NaCl crystals on water condensation and on electrochemical migration processes (ECM) were investigated in case of different lead bearing and lead-free solder alloys on FR4 substrate during a special Thermal-humidity Bias (THB) test, called dew point test. The dew point test simulated the water condensation process and ECM, which processes were followed by in-situ optically and simultaneously...
This paper verifies and discusses the structure of charismatic leadership style of management layer of fire protection unit, and develops a measuring tool that has a good reliability and validity to measure charismatic leadership style with each department office's staff of eight fire protection squadrons as research objects, based on the questionnaire of charismatic leadership style that was compiled...
The main trends in consumer electronics are increasing product performances and costs reduction. These trends lead to an ongoing integration on package level which leads to a decreasing size of the solder contacts. This goes along with a higher sensibility to thermal-mechanical stress and the immanent void formation due to electromigration (EM) effects in interfaces and bulk materials like solder...
Due to the nature of many-to-one or many-to-few traffic patterns in Wireless Sensor Networks (WSNs), some critical nodes overload and tend to exhaust their energy at an early age bringing the whole network down. Typically, most routing algorithms employ a reliable cost metric to route the data but are unable to ensure balanced energy consumption from all the nodes in the WSN. In this paper, we have...
Aerospace, Defence and High Performance (ADHP) industry has little choice but to rely on the use of commercial-of-the-shelf (COTS) electronics components for their products and equipment. As these electronics components are now predominantly packaged as lead-free (Pb-free) to comply with RoHS and other similar legislations, their use in high reliability and long service life applications is highly...
Mean Time Between Failures (MTBF), now calculated in days or hours, is expected to drop to minutes on exascale machines. The advancement of resilience technologies greatly depends on a deeper understanding of faults arising from hardware and software components. This understanding has the potential to help us build better fault tolerance technologies. For instance, it has been proved that combining...
For a cognitive radio network (CRN), there are many studies on transmission throughput of secondary users (SUs) with a fixed status for the primary user (PU) during the test period. In this paper, we consider a medium-traffic primary network, in which the PU changes its state (either idle or active) at most once during the frame time. This instability degrades the detection performance of SUs as well...
In this study, the effect of series Pb content on shear performance of SnAgCu-xSnPb/Cu solder joint was investigated. It was found that Pb content influenced the BGA solder joint shear strength significantly. The shear strength as a function of Pb content shows a parabola trend. The shear strength increased with Pb content increased from 0% to 9.22%. Then the shear strength value kept at a high level...
Ni film electroplated between matte tin film and Cu-based lead-frame was used as a diffusion barrier to prevent whisker formation on the tin surface through blocking the formation of Cu6Sn5 intermetallics. The interfacial microstructure of Sn/Ni and Sn/Cu which formed after reflow treatment and the following humidity/thermal testing were characterized by SEM and BSE. The testing results indicated...
Electronic assembly technology is in the transition from traditional tin-lead to lead-free. In comparison with Sn-Pb solders, high melting point and poor wettability of the lead-free solders lead to great challenge in many aspects. It has been accepted that inert N2 atmosphere can improve the wettability and reliablity of solder joints. The focus of this study is to investigate the reliability of...
In this paper, a serious crack phenomenon of Backward Compatible Assembled BGA joint with reflow and waving process was found and solved by the optimization of soldering process. The quality of BGA solder joints was confirmed after optimization. The mechanism of such cracking was illustrated.
Based on the JEDEC standard, the three-dimensional finite element model of board level VFBGA package components was established, and the reliability of low silver lead-free solder Sn0.3Ag0.7Cu under drop impact was observed. The results show that, the mechanical impact and bending of PCB caused by mechanical shock are the main reasons which induce the drop failure of solder joint in the drop impact...
This work was designed for low-temperature mechanical properties of the solder joints, the temperature is 293K, 223K, 173K, and 123K, in order to get the mechanical strength and mechanism of fracture at low temperature; Cryogenic temperature (77K) storage experiment is applied to get microstructure of internal solder joint, and the evolution of IMC and other microstructures, as well as solder joints'...
The compact and high-performance Lead-free BGA device has become the modern highly integrated device which is required in electronics assembly. In the course of service, they experience thermal cycling and become invalid. The failure mode of BGA device, which has undergone the thermal cycling, is investigated by scanning electronic microscope, electron back scattered diffraction and micro Vickers...
Lead-free solder alloys are more easily oxygenized and have poor wettability compared to traditional Sn-Pb solder alloys, which affects solder joints reliability. Ar is the most plentiful rare inert gas. It has been accepted that, in Ar atmosphere, the oxidation of lead-free solder joints can be prevented and the wettability of lead-free solder joints can be improved. To date, however, few systemic...
The main objective of this paper is to investigate the reliability of Sn-1.0Ag-0.5Cu low-Ag lead-free solder alloy. The wettability, mechanical property and microstructure of Sn-1.0Ag-0.5Cu (SAC105) and Sn-3.0Ag-0.5Cu (SAC305) lead-free solder alloys were comparatively investigated. Experimental studies have shown that the wetting property of low-Ag lead-free solder alloy SAC105 remains to be improved...
Partial Discharge (PD) is the most important issue that arise when testing service aged and non-aged cables. For long time, High Voltage Direct Current (HVDC) was used to detect the occurrence of PD activity in cables. Due to technical reasons, the HVDC was replaced by the Very Low Frequency (VLF). Wide range of frequencies and wave forms were used for this purpose. This paper presents an evaluation...
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