Analytical and Experimental Characterization of Bonding Over Active Circuitry

2005 ◽  
Author(s):  
Li Zhang ◽  
Vijaylaxmi Gumaste ◽  
Anindya Poddar ◽  
Luu Nguyen ◽  
Gary Schulze
Keyword(s):  
Principal Stress ◽  
Dielectric Layer ◽  
Current Model ◽  
Real Life ◽  
Wire Bonding ◽  
Friction Model ◽  
Main Concern ◽  
Fe Model ◽  
Experimental Characterization ◽  
Stress Criterion

Placing active circuitry directly underneath the bond pads is an effective way to reduce the die size, and hence to achieve lower cost per chip. The main concern with such design is the possible mechanical damage to the underlying circuitry during the wire bonding process. For example, the initial bond force and subsequent ultrasonic vibration may cause cracks within the dielectric layer. The cracks can penetrate through the active circuitry underneath, resulting in electrical failures to the silicon device. At the present time, most studies found in the literature rely heavily on experimental characterization to study pad integrity. The characterization typically involves building test devices and conducting real-life bonding test. On the other hand, while there are few studies attempting to describe the stress-strain behavior of the process by numerical simulations, most are based on either over-simplified models or incomplete analysis. Furthermore, nearly all of these studies failed to provide any correlation with real test data, and hence the accuracy of the analysis becomes questionable. In this paper, we have developed a finite element based methodology to study the stress behavior of bond pad structures during thermo-sonic wire bonding. Unlike most previous studies, which used 2-D models and plane-strain assumption, the current model captures the 3-D structure of the bond pad and gold ball. The incremental principal stress at the dielectric layer was used as the stress criterion to correlate with dielectric cracking, which is the dominant failure mode during our bonding experiments. The dynamic friction coefficient at the gold-aluminum interface is found to be responsible to the change in magnitude and location of the peak stress. To validate the simulation results, two engineering test chips were built and bonded. The dielectric cracks were found to correlate well with the incremental principal stress. Furthermore, we have shown that the interfacial friction model was able to account for the difference in crack pattern. The FE model is expected to study the relative crack resistance for other bonding over active circuitry pad structures currently under consideration.

Analytical and Experimental Characterization of Bonding Over Active Circuitry

2006 ◽  
Vol 129 (4) ◽  
pp. 391-399 ◽  
Author(s):  
Li Zhang ◽  
Vijaylaxmi Gumaste ◽  
Anindya Poddar ◽  
Luu Nguyen ◽  
Gary Schulze
Keyword(s):  
Finite Element ◽  
Dielectric Layer ◽  
Real Life ◽  
Wire Bonding ◽  
Main Concern ◽  
Fe Model ◽  
Stress Criterion ◽  
Bond Force ◽  
The Wire ◽  
Thermosonic Wire Bonding

Placing active circuitry directly underneath the bond pads is an effective way to reduce the die size, and hence to achieve lower cost per chip. The main concern with such design is the possible mechanical damage to the underlying circuitry during the wire bonding process. For example, the initial bond force and subsequent ultrasonic vibration may cause cracks within the dielectric layer. The cracks can penetrate through the active circuitry underneath, resulting in electrical failures to the silicon device. In this paper, a finite element based methodology was developed to study the stress behavior of bond pad structures during thermosonic wire bonding. The focus of our analysis is on dielectric layer crack, which was the dominant failure mode observed. The finite element (FE) model is 3-D based and contains the wire ball, the bond pad, and the underpad structure. The model was subjected to various bond force/ultrasound conditions, and the stresses were compared with the percentage of cracked pads in the real life bonding experiments. By using the volume-averaged, incremental first principal stress at the dielectric layer as the stress criterion, we achieved a reasonably good correlation with the experiments. In addition, we found that the dynamic friction at the bond interface is critical in stress distributions at the bond pad. Based on this, we have provided an explanation on how stresses progress during a typical bond force. Furthermore, the stress progression pattern was shown to correlate well with the different crack patterns. The FE model established a baseline upon which more designs with bonding over active circuitry can be analyzed and evaluated for crack resistance to thermosonic wire bonding.

Modeling and Experimental Study of a Wire Clamp for Wire Bonding

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Fuliang Wang ◽  
Dengke Fan
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Energy Conservation ◽  
Design Process ◽  
Gold Wire ◽  
Wire Bonding ◽  
Fe Model ◽  
Amplification Ratio ◽  
Model Studies ◽  
Thermosonic Wire Bonding

A wire clamp is used to grip a gold wire with in 1–2 ms during thermosonic wire bonding. Modern wire bonders require faster and larger opening wire clamps. In order to simplify the design process and find the key parameters affecting the opening of wire clamps, a model analysis based on energy conservation was developed. The relation between geometric parameters and the amplification ratio was obtained. A finite element (FE) model was also developed in order to calculate the amplification ratio and natural frequency. Experiments were carried out in order to confirm the results of these models. Model studies show that the arm length was the major factor affecting the opening of the wire clamp.

In Silico Finite Element Analysis of the Foot Ankle Complex Biomechanics: A Literature Review

2021 ◽  
Author(s):  
Phong Phan ◽  
Anh Vo ◽  
Amirhamed Bakhtiarydavijani ◽  
Reuben Burch ◽  
Brian K. Smith ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
In Silico ◽  
Real Life ◽  
Ankle Injuries ◽  
Fe Model ◽  
Foot And Ankle ◽  
Element Analysis ◽  
Ankle Complex ◽  
Biomechanics Of The Foot

Abstract Computational approaches, especially Finite Element Analysis (FEA), have been rapidly growing in both academia and industry during the last few decades. FEA serves as a powerful and efficient approach for simulating real-life experiments, including industrial product development, machine design, and biomedical research, particularly in biomechanics and biomaterials. Accordingly, FEA has been a "go-to" high biofidelic software tool to simulate and quantify the biomechanics of the foot-ankle complex, as well as to predict the risk of foot and ankle injuries, which are one of the most common musculoskeletal injuries among physically active individuals. This paper provides a review of the in silico FEA of the foot-ankle complex. First, a brief history of computational modeling methods and Finite Element (FE) simulations for foot-ankle models is introduced. Second, a general approach to build a FE foot and ankle model is presented, including a detailed procedure to accurately construct, calibrate, verify, and validate a FE model in its appropriate simulation environment. Third, current applications, as well as future improvements of the foot and ankle FE models, especially in the biomedical field, are discussed. Lastly, a conclusion is made on the efficiency and development of FEA as a computational approach in investigating the biomechanics of the foot-ankle complex. Overall, this review integrates insightful information for biomedical engineers, medical professionals, and researchers to conduct more accurate research on the foot-ankle FE models in the future.

A Comprehensive Study on Burst Pressure Performance of Aluminum Liner for Hydrogen Storage Vessels

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Serkan Kangal ◽  
A. Harun Sayı ◽  
Ozan Ayakdaş ◽  
Osman Kartav ◽  
Levent Aydın ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Axial Strain ◽  
Cylindrical Part ◽  
Pressure Vessels ◽  
Fe Analysis ◽  
Burst Pressure ◽  
Experimental Investigations ◽  
Fe Model ◽  
Stress Criterion ◽  
Analytical Approaches

Abstract This paper presents a comparative study on the burst pressure performance of aluminum (Al) liner for type-III composite overwrapped pressure vessels (COPVs). In the analysis, the vessels were loaded with increasing internal pressure up to the burst pressure level. In the analytical part of the study, the burst pressure of the cylindrical part was predicted based on the modified von Mises, Tresca, and average shear stress criterion (ASSC). In the numerical analysis, a finite element (FE) model was established in order to predict the behavior of the vessel as a function of increasing internal pressure and determine the final burst. The Al pressure vessels made of Al-6061-T6 alloy with a capacity of 5 L were designed. The manufacturing of the metallic vessels was purchased from a metal forming company. The experimental study was conducted by pressurizing the Al vessels until the burst failure occurred. The radial and axial strain behaviors were monitored at various locations on the vessels during loading. The results obtained through analytical, numerical, and experimental work were compared. The average experimental burst pressure of the vessels was found to be 279 bar. The experimental strain data were compared with the results of the FE analysis. The results indicated that the FE analysis and ASSC-based elastoplastic analytical approaches yielded the best predictions which are within 2.2% of the experimental burst failure values. It was also found that the elastic analysis underestimated the burst failure results; however, it was effective for determining the critical regions over the vessel structure. The strain behavior of the vessels obtained through experimental investigations was well correlated with those predicted through FE analysis.

ASME Sec VIII Div 3 Fatigue Life Predictions Using Critical Plane Approach

2015 ◽  
Author(s):  
Kumarswamy Karpanan ◽  
William Thomas
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Principal Stress ◽  
Stress Amplitude ◽  
Maximum Shear Stress ◽  
Fe Model ◽  
Critical Plane ◽  
Principal Stress Direction ◽  
Stress Direction ◽  
Surface Node

ASME VIII Div 3 fatigue evaluation is based on the theory that cracks tend to nucleate along the slip lines oriented in the maximum shear stress planes. This code provides methods to calculate the fatigue stresses when the principal stress direction does not change (proportional loading) and axes change (nonproportional loading). When principal stress direction does not change within a fatigue cycle, shear stress amplitude is calculated only on the three maximum shear stress planes. But when the principal stress directions do change within a loading cycle, the plane carrying the maximum shear stress amplitude (also known as critical plane) cannot be easily identified and all planes at a point needs to be searched for the maximum shear stress amplitude. This paper describes the development of an ANSYS-APDL macro to predict the critical plane at each surface node of an FE model using the FEA stress results. This macro searches through 325 planes (at 10° increments along two angles) at each surface node and for each load step to identify the maximum shear stress and the corresponding normal stress for each surface node. The fatigue life is calculated for each surface node and is plotted as a color contour on the FEA model. This macro can be extended to calculate the fatigue life using other critical plane approaches such as the Findley and Brown-Miller models.

Bikeability in Basel

2019 ◽  
Vol 2673 (6) ◽  
pp. 607-617 ◽  
Author(s):  
Elena Grigore ◽  
Norman Garrick ◽  
Raphael Fuhrer ◽  
Ing. Kay W. Axhausen
Keyword(s):  
Urban Planning ◽  
Quantitative Method ◽  
Current Model ◽  
Real Life ◽  
Underlying Assumption ◽  
Perceived Safety ◽  
Distance Weighted ◽  
The City ◽  
Turn Direction

“Bikeability” is becoming increasingly relevant in the field of transport- and urban planning. However, it is often unclear how bikeability is defined, let alone how it can be modeled. The goal of this project was to develop a quantitative method to model bikeability. A case study area in the city of Basel, Switzerland was selected for assessing the model. Here “bikeability” is understood as a measure of the ability and convenience in reaching important destinations by bike, based on the travel distance weighted by the perceived safety, -comfort, and -attractiveness of the streets and intersections along the routes. The underlying assumption was that cyclists try to minimize the distance traveled and maximize the perceived safety, -comfort, and -attractiveness of their route of choice. Unlike most of the previous bikeability assessments we reviewed, our method used existing route choice studies to identify attributes for quantifying cycling quality, which presumably results in a model that more accurately reflects real-life behavior. Many relevant attributes that have not been captured by previous models are included in this work, such as the high curbs of tram stops, tram tracks, and the turn direction at intersections. The method is suitable for several applications in urban planning, such as the identification of locations that need improvement and the comparison of planning measures. The current model covers conventional bikes used by commuting cyclists. However, the method could be used for E-bikes and non-commuting cyclists by applying the appropriate input values.

Multi-Objective Model Updating Optimization Considering Orthogonality

2019 ◽  
Vol 14 (6) ◽  
Author(s):  
Braden T. Warwick ◽  
Il Yong Kim ◽  
Chris K. Mechefske
Keyword(s):  
Mode Shape ◽  
Degrees Of Freedom ◽  
Pareto Front ◽  
Model Updating ◽  
Current Model ◽  
Physical Reality ◽  
Frequency Error ◽  
Fe Model ◽  
Multi Objective ◽  
Objective Model

The coordinate orthogonality check (CORTHOG) and multi-objective optimization considering pseudo-orthogonality as an objective function are introduced to overcome several limitations present in current model updating methods. It was observed that the use of the CORTHOG to remove four inaccurate degrees-of-freedom (DOF) was able to increase the orthogonality between mode shape vectors. The multi-objective model updating process generated a Pareto front with 38 unique optimal solutions. Four critical points were identified along the Pareto front, of which decreased the natural frequency error by greater than 2.84% and further increased the orthogonality between mode shape vectors. Therefore, it has been demonstrated that both steps of the methodology are critical to significantly reduce the overall errors of the system and to generate a finite element (FE) model that best describes physical reality. Additionally, the methodology introduced in this work generated a feasible computational runtime allowing for it to be easily adapted to widespread applications.

3D Nonlinear Finite Element Analysis of Knee Joint Implants

1999 ◽  
Author(s):  
A. Hashemi ◽  
A. Shirazi-Adl
Keyword(s):  
Finite Element ◽  
3D Models ◽  
Friction Model ◽  
Design Parameters ◽  
Fe Model ◽  
Fe Method ◽  
Element Analysis ◽  
Bone Implant ◽  
Coulomb’S Friction ◽  
Model Studies

Abstract The finite element (FE) method has been used in orthopaedic biomechanics to investigate the fixation role of different design parameters in total knee replacement (TKA). Previous FE model studies used 2D, axisymmetric and 3D models to represent the geometry while neglecting many essential features. They simulated the bone-implant interface as frictionless, perfectly bonded or with idealized Coulomb’s friction model. The model of screws and posts have also been neglected altogether or inadequately considered in these studies. To overcome these limitations, the objective of the present study was set to develop a detailed 3D FE model of the knee bone-implant structure including all the interacting components in an immediate postoperative period without bony ingrowth to predict the micromotion at the bone-implant interface and stress distribution within the bone and the polyethylene insert.

Development and Validation of A C0–C7 FE Complex for Biomechanical Study

2005 ◽  
Vol 127 (5) ◽  
pp. 729-735 ◽  
Author(s):  
Qing Hang Zhang ◽  
Ee Chon Teo ◽  
Hong Wan Ng
Keyword(s):  
Current Model ◽  
Drop Impact ◽  
Biomechanical Study ◽  
Fe Model ◽  
Midsagittal Plane ◽  
Male Cadaver ◽  
Geometrical Data ◽  
Fe Complex ◽  
Development And Validation ◽  
Head Neck

In this study, the digitized geometrical data of the embalmed skull and vertebrae (C0–C7) of a 68-year old male cadaver were processed to develop a comprehensive, geometrically accurate, nonlinear C0–C7 FE model. The biomechanical response of human neck under physiological static loadings, near vertex drop impact and rear-end impact (whiplash) conditions were investigated and compared with published experimental results. Under static loading conditions, the predicted moment-rotation relationships of each motion segment under moments in midsagittal plane and horizontal plane agreed well with experimental data. In addition, the respective predicted head impact force history and the S-shaped kinematics responses of head-neck complex under near-vertex drop impact and rear-end conditions were close to those observed in reported experiments. Although the predicted responses of the head-neck complex under any specific condition cannot perfectly match the experimental observations, the model reasonably reflected the rotation distributions among the motion segments under static moments and basic responses of head and neck under dynamic loadings. The current model may offer potentials to effectively reflect the behavior of human cervical spine suitable for further biomechanics and traumatic studies.

Vibrational and Acoustical Analysis of Trussed Railroad Bridge Under Moving Loads

2012 ◽  
Author(s):  
R. Daniel Costley ◽  
Henry Diaz-Alvarez ◽  
Mihan H. McKenna
Keyword(s):  
Structural Damage ◽  
Current Model ◽  
Element Model ◽  
Vehicle Suspension ◽  
Fe Model ◽  
Vibrational Modes ◽  
Moving Loads ◽  
Vehicle Loading ◽  
Vibration Responses ◽  
Railroad Bridge

A Finite Element model has been developed for a Pratt truss railroad bridge located at Ft. Leonard Wood, MO. This model was used to investigate the vibration responses of a bridge under vehicle loading. Modeling results have been obtained for a single axle with two wheels traversing the bridge at different speeds. The current model does not include the effects of vehicle suspension. Superposition of multiple axles has been used to represent a locomotive transiting the bridge. The output of the vibration response was used as an input to an acoustic FE model to determine which vibrational modes radiate infrasound. The vibration and acoustic models of the railroad bridge will be reviewed, and results from the analysis will be presented. Measurements from an accelerometer mounted on the bridge agree reasonably well with model results. Infrasound could potentially be used to remotely provide information on the capacity and number of the vehicles traversing the bridge and to monitor the bridge for significant structural damage.

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