Interface Cracking of Plastic Electronic Package under Temperature and Humidity Environment

2007 ◽  
Vol 353-358 ◽  
pp. 2940-2943
Author(s):  
Xu Chen ◽  
Shu Feng Zhao ◽  
Linda Zhai
Keyword(s):  
Thermal Expansion ◽  
Vapor Pressure ◽  
Crack Propagation ◽  
Crack Length ◽  
Structural Model ◽  
Electronic Package ◽  
Temperature And Humidity ◽  
Interface Cracking ◽  
The Impact ◽  
Humidity Environment

Structural model of plastic electronic package under temperature and humidity is constructed, and the coupling of the thermal and moisture impact on structure field is implemented. The impact of thermal expansion, hygro-swelling and vapor pressure increases with increasing initial defect, especially the impact of vapor pressure. At certain crack length, KI and KII induced by thermal expansion is proportional to temperature difference, and KI and KII induced by vapor is proportional to vapor pressure. The impacts of thermal expansion and hygro-swelling on ERR decrease during crack propagation, but the impact of vapor pressure increases significantly.

A finite element model on effects of impact load and cavitation on fatigue crack propagation in mechanical bileaflet aortic heart valve

2008 ◽  
Vol 222 (7) ◽  
pp. 1115-1125 ◽  
Author(s):  
H Mohammadi ◽  
R J Klassen ◽  
W-K Wan
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Crack Length ◽  
Heart Valve ◽  
Heart Valves ◽  
Element Model ◽  
Initial Crack ◽  
Initial Crack Length ◽  
Element Approach ◽  
The Impact

Pyrolytic carbon mechanical heart valves (MHVs) are widely used to replace dysfunctional and failed heart valves. As the human heart beats around 40 million times per year, fatigue is the prime mechanism of mechanical failure. In this study, a finite element approach is implemented to develop a model for fatigue analysis of MHVs due to the impact force between the leaflet and the stent and cavitation in the aortic position. A two-step method to predict crack propagation in the leaflets of MHVs has been developed. Stress intensity factors (SIFs) are computed at a small initiated crack located on the leaflet edge (the worst case) using the boundary element method (BEM). Static analysis of the crack is performed to analyse the stress distribution around the front crack zone when the crack is opened; this is followed by a dynamic crack analysis to consider crack propagation using the finite element approach. Two factors are taken into account in the calculation of the SIFs: first, the effect of microjet formation due to cavitation in the vicinity of leaflets, resulting in water hammer pressure; second, the effect of the impact force between the leaflet and the stent of the MHVs, both in the closing phase. The critical initial crack length, the SIFs, the water hammer pressure, and the maximum jet velocity due to cavitation have been calculated. With an initial crack length of 35 μm, the fatigue life of the heart valve is greater than 60 years (i.e. about 2.2×109 cycles) and, with an initial crack length of 170 μm, the fatigue life of the heart valve would be around 2.5 years (i.e. about 9.1×107 cycles). For an initial crack length greater than 170 μm, there is catastrophic failure and fatigue cracking no longer occurs. A finite element model of fatigue analysis using Patran command language (PCL custom code) in MSC software can be used to evaluate the useful lifespan of MHVs. Similar methodologies can be extended to other medical devices under cyclic loads.

A Compliance-Based Approach to Study Fatigue Crack Propagation for a Copper-Epoxy Interface

2015 ◽  
Author(s):  
David Samet ◽  
Abhishek Kwatra ◽  
Suresh K. Sitaraman
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Length ◽  
Fatigue Crack Propagation ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
Propagation Model ◽  
Operational Life ◽  
The Impact

As the microelectronics industry continues to advance the boundaries of size and performance, focus on the impact of systems packaging has risen to the forefront of design and material considerations. As interfaces are often constructed of multiple heterogeneous layers, interfacial delamination is an important failure mechanism to consider in microelectronic packaging. This failure is due to, among other factors, the stresses arising from high mismatches in coefficient of thermal expansion (CTE). Most work to date has focused on interfacial crack propagation under monotonic loading that is incurred during fabrication steps such as deposition or curing which occur at elevated temperatures and subsequent cooling to room temperature. This is an important design consideration but it is not sufficient as the operational life of these devices involve high numbers of heating and cooling cycles which result in crack propagation under fatigue loading. As such the study of fatigue effects on these interfaces is paramount to improving the lifetime of microelectronic devices as the field pushes towards both thinner and wider packages. One such exploration, which is the subject of this work, is to determine the interface incremental crack growth rate as it relates to cyclic loading. In this work, double cantilever beam (DCB) tests are performed at various stress ratios on samples with epoxy mold compound (EMC) atop a copper leadframe. For these tests, force versus displacement curves will be obtained. Given the small dimensions of the interfaces in question, it is desirable to develop a test methodology that does not require in-situ measurement of crack length. Thus, in these tests the compliance of the samples is determined from the force versus displacement curves and used to infer the progress of the crack through an indirect approach. The advantage of this method is that it does not require the observational measurement of the crack length potentially allowing crack monitoring absent any optical or imaging methods. Using the determined crack propagation rate with fatigue cycle under various loading conditions, a generalized fatigue crack propagation model will be developed for mold compound and copper interface, and such a model can be employed to assess packaging reliability in operating conditions.

Structural Modeling of Institute of Entrepreneurship in Russia

2019 ◽  
pp. 34-48
Author(s):  
Svetlana L. Sazanova
Keyword(s):  
Global Economy ◽  
Structural Model ◽  
Institutional Environment ◽  
Small And Medium Enterprises ◽  
Structural Modeling ◽  
Entrepreneurial Activity ◽  
Pattern Modeling ◽  
Medium Enterprises ◽  
The Impact ◽  
The Relationship

Entrepreneurship plays an important role in the modern global economy; the share of products of small and medium enterprises in the gross product and exports not only of the developed but also of developing countries is growing. Innovation processes cover all sectors of the economy, and more and more people are involved in entrepreneurial activity, which contributes to the penetration of entrepreneurial thinking and business values in all areas of the socioeconomic life of society. The Institute of Entrepreneurship plays an increasingly prominent role in the institutional environment of socio-economic systems. This actualizes the problem of studying the relationship of the institution of entrepreneurship with the institutions of law, culture, management. This requires a methodology that allows you to explore the impact on the institute of entrepreneurship not only economic, but also non-economic factors. The methodology of the “old” institutionalism possesses such a tool, it is structural modeling (pattern modeling), which allows to explore the diversity of interrelationships of the institution of entrepreneurship with other components of the institutional and economic environment. The article explored the features of the development of the institution of entrepreneurship in Russia, established the relationship between the institution of entrepreneurship, values, motives and incentives for entrepreneurial activity, built a structural model of the institution of entrepreneurship based on the methodology of the old institutionalism (pattern modeling). The structural model of the institution of entrepreneurship reveals the relationship between the institution of entrepreneurship, the values of entrepreneurial activity, its motives and incentives; as well as the relationship between the institution of entrepreneurship with the institutions of governance, cultural and religious institutions, legal institutions and society.

Structural Model of Service Quality Factors Affecting Loyalty Sustainability

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Eman Al-erqi ◽  
◽  
Mohd Lizam Mohd Diah ◽  
Najmaddin Abo Mosali ◽  
◽  
...  
Keyword(s):  
International Students ◽  
Service Quality ◽  
Goodness Of Fit ◽  
Structural Model ◽  
Quality Factors ◽  
Factors Affecting ◽  
Measurement Models ◽  
Confirmatory Factor ◽  
The University ◽  
The Impact

This study seeks to address the impact of service quality affecting international student's satisfaction towards loyalty tothe Universiti Tun Hussein Onn Malaysia(UTHM). The aim of thestudy is to develop relationship between service quality factor and loyalty to the university from the international students’ perspectives. The study adopted quantitative approach where data was collected through questionnaire survey and analysed statistically. A total of 246 responses were received and found to be valid. The model was developed and analysed using AMOS-SEM software. Confirmatory factor analysis (CFA) function of the software was to assessed the measurement models and found that all the models achieved goodness of fit. Then path analysis function was used to assessed structural model and found that service qualityfactors have a significant effect on the students’ satisfaction and thus affecting the loyaltyto the university. Hopefully the outcome form this study will benefit the university in providing services especially to the international students.

The Impact of Service Satisfaction, Relational Satisfaction and Commitment on Customer Loyalty in Logistics Outsourcing Relationship

2015 ◽  
Vol 4 (1and2) ◽  
Author(s):  
Sanjit Singh H.
Keyword(s):  
Customer Loyalty ◽  
Structural Equation ◽  
Structural Model ◽  
Reliability And Validity ◽  
Service Satisfaction ◽  
Equation Modeling ◽  
Relational Satisfaction ◽  
Logistics Outsourcing ◽  
Major Predictor ◽  
The Impact

This research explores the impact of service satisfaction, relational satisfaction, price satisfaction, and commitment on customer loyalty in logistics outsourcing relationships in Indian scenario. 254 users of logistics services from India were selected for investigating the potential linkages among the aforementioned satisfaction aspects and loyalty. Structural equation modeling (SEM) was employed to test the reliability and validity of the measurement and structural model developed to study the relationship among the linkages. Findings from the study supports that logistics service satisfaction, price satisfaction, relational satisfaction and commitment do influence loyalty positively. The analysis suggests that service satisfaction is the most important antecedent having primary influence in the formation of customer loyalty. Service satisfaction also has secondary influence on loyalty by acting as a strong driver in both relational satisfaction and commitment aspects of the service dimensions. Price satisfaction though positively been driven by service satisfaction, was found to have less significant effect as a predictor of loyalty in this context. The present study suggests that relational satisfaction is the second major predictor of loyalty which also drives commitment. This research is not an end-point but an attempt to establish the linkages and the effect among the antecedents driving the building and retention of good buyer-seller relationship in logistics outsourcing.

The effect of emotions, eWOM quality and online review sequence on consumer intention to follow advice obtained from digital services

2020 ◽  
Vol 31 (3) ◽  
pp. 465-487 ◽  
Author(s):  
Carla Ruiz-Mafe ◽  
Enrique Bigné-Alcañiz ◽  
Rafael Currás-Pérez
Keyword(s):  
Structural Model ◽  
Online Reviews ◽  
Moderating Effect ◽  
Online Information ◽  
Bias Effect ◽  
Content Type ◽  
Digital Services ◽  
Information Cues ◽  
Cognitive Information ◽  
The Impact

PurposeThis paper analyses the interrelationships between emotions, the cognitive information cues of online reviews and intention to follow the advice obtained from digital platforms, paying special attention to the moderating effect of the sequencing of review valence.Design/methodology/approachThe data were collected from 830 Spanish Tripadvisor users. In a two-step approach, a measurement model was estimated and a structural model analysed to test the proposed hypotheses. SmartPLS 3.0 software was used. The moderating effect of sequencing of reviews is tested.FindingsThe data analysis showed a bias effect of review sequence on the impact of online information cues and emotions on intention to follow advice obtained from Tripadvisor. When the online reviews of a restaurant begin with positive commentaries, their perceived persuasiveness is a stronger driver of the pleasure and arousal elicited by online reviews than when they begin with negative reviews. On the other hand, the perceived helpfulness of online reviews only triggers arousal when the user reads negative, followed by positive, comments. The impact of pleasure on intention to follow the advice provided in an online travel community is higher with positive-negative than with negative-positive sequences.Originality/valueWhile researchers have demonstrated the benefits of customer reviews on company sales, a largely uninvestigated issue is the interplay between emotions and cognitive information cues in the processing of online reviews. This is one of the first studies to examine the moderating effect of conflicting reviews on the impact of emotions and cognitive information cues on consumer intention to follow the advice obtained from digital services.

Eating Behavior of Brazilian College Students: Influences of Lifestyle, Negative Affectivity, and Personal Characteristics

2020 ◽  
pp. 003151252098308
Author(s):  
Bianca G. Martins ◽  
Wanderson R. da Silva ◽  
João Marôco ◽  
Juliana A. D. B. Campos
Keyword(s):  
College Students ◽  
Eating Behavior ◽  
Emotional Eating ◽  
Eating Behaviors ◽  
Structural Model ◽  
Negative Affectivity ◽  
Personal Characteristics ◽  
Second Order ◽  
The Impact ◽  
The Relationship

In this study we proposed to estimate the impact of lifestyle, negative affectivity, and college students’ personal characteristics on eating behavior. We aimed to verify that negative affectivity moderates the relationship between lifestyle and eating behavior. We assessed eating behaviors of cognitive restraint (CR), uncontrolled eating (UE), and emotional eating (EE)) with the Three-Factor Eating Questionnaire-18. We assessed lifestyle with the Individual Lifestyle Profile, and we assessed negative affectivity with the Depression, Anxiety and Stress Scale-21. We constructed and tested (at p < .05) a hypothetical causal structural model that considered global (second-order) and specific (first-order) lifestyle components, negative affectivity and sample characteristics for each eating behavior dimension. Participants were 1,109 college students ( M age = 20.9, SD = 2.7 years; 65.7% females). We found significant impacts of lifestyle second-order components on negative affectivity (β = −0.57–0.19; p < 0.001–0.01) in all models. Physical and psychological lifestyle components impacted directly only on CR (β=−0.32–0.81; p < 0.001). Negative affectivity impacted UE and EE (β = 0.23–0.30; p < 0.001). For global models, we found no mediation pathways between lifestyle and CR or UE. For specific models, negative affectivity was a mediator between stress management and UE (β=−0.07; p < 0.001). Negative affectivity also mediated the relationship between thoughts of dropping an undergraduate course and UE and EE (β = 0.06–0.08; p < 0.001). Participant sex and weight impacted all eating behavior dimensions (β = 0.08–0.34; p < 0.001–0.01). Age was significant for UE and EE (β=−0,14– −0.09; p < 0.001–0.01). Economic stratum influenced only CR (β = 0.08; p = 0.01). In sum, participants’ lifestyle, negative emotions and personal characteristics were all relevant for eating behavior assessment.

scholarly journals Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2690
Author(s):  
Bo Pan ◽  
Xuguang Wang ◽  
Zhenyang Xu ◽  
Lianjun Guo ◽  
Xuesong Wang
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Joint Angle ◽  
Simulation Software ◽  
Dissipated Energy ◽  
Energy Structure ◽  
Joint Angles ◽  
Crack Penetration ◽  
Before And After ◽  
The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

scholarly journals The Impact of Force Factors on the Benefits of Digital Transformation in Romania

2021 ◽  
Vol 11 (5) ◽  
pp. 2365
Author(s):  
Sorinel Căpușneanu ◽  
Dorel Mateș ◽  
Mirela Cătălina Tűrkeș ◽  
Cristian-Marian Barbu ◽  
Adela-Ioana Staraș ◽  
...  
Keyword(s):  
Perceived Risk ◽  
Industry 4.0 ◽  
Business Models ◽  
Structural Model ◽  
Digital Transformation ◽  
Sample Survey ◽  
Intention To Use ◽  
Online Questionnaire ◽  
Use Of Technology ◽  
The Impact

The digital transformation has produced changes in all existing areas of activity worldwide. There are many factors that can influence the intention to use Industry 4.0 processes and solutions and change the behavior of organizations and their business models. The aim of this study is to validate the econometric model on assessing the significant impact of distinct factors on the intention to use Industry 4.0 processes and solutions, the benefits of digital transformation perceived by organizational management and the differences between distinct groups analyzed. The research method used within the quantitative study was the sample survey, using the online questionnaire as a data collection tool. Three hundred forty-seven valid questionnaires were collected and the response rate of the respondents was 64.25%. A new structural model was generated based on the elements of the Unified Theory of Acceptance and Use of Technology (UTAUT). The results of the study indicated that Perceived competitiveness and Perceived risk have a significant impact on Intention to Use Industry 4.0 processes while Perceived vertical networking solutions and Perceived integrated engineering solutions have a significant influence on the Intention to Use Industry 4.0 solutions. In conclusion, there is a positive and significant association between Intention to Use Industry 4.0 solutions and Benefits of Digital Transformation.

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