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.

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.

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.

The effect of clamping a tensioned wire: Implications for the Ilizarov external fixation system

2003 ◽  
Vol 217 (2) ◽  
pp. 91-98 ◽  
Author(s):  
M A Watson ◽  
K J Mathias ◽  
N Maffulli ◽  
D W L Hukins
Keyword(s):  
Finite Element ◽  
Standard Deviation ◽  
External Fixator ◽  
Clinical Situation ◽  
Engineering Problem ◽  
Fe Model ◽  
Ilizarov External Fixator ◽  
Wire Tension ◽  
The Wire ◽  
Fixation System

This study demonstrates that clamping a tensioned wire can cause a reduction in wire tension. Tension (about 1275 N) was applied to a wire that was subsequently clamped, using cannulated bolts, to the steel half-ring of an Ilizarov external fixator. The tension in the wire was monitored before, during and after clamping. The apparatus was disassembled and the deformations in the wire caused by the clamps were measured. This experiment was repeated 15 times. When the wire was clamped to the frame, the wire tension was reduced by 22 ± 7 per cent (mean ± standard deviation, SD). The drop in wire tension was linearly correlated ( r = 0.96; p < 0.001) with the deformation caused by the bolts. A finite element (FE) model of the wire was also constructed. The model was pre-stressed (tensioned), and the clamping effect replicated. This analysis showed that clamping the wire could be considered to squeeze the wire outwards (like toothpaste from a tube) and so reduce its tension during fixator assembly. To assess the magnitude of this effect in the clinical situation, the FE model analysis was repeated to replicate clamping a 1.8-mm-diameter wire to a 180-mm-diameter steel Ilizarov ring component. The analysis showed that for these conditions the tension reduced by 8–29 per cent. The results of this study highlight a general engineering problem: how can a tensioned wire be secured to a structure without an appreciable loss of tension? If the performance of the structure depends on the wire tension, this performance will change when the wire is secured.

Finite Element Analysis on Thermosonic Ball Bonding Process of MEMS Chip

2014 ◽  
Vol 609-610 ◽  
pp. 1153-1158
Author(s):  
Dong Rui Wang ◽  
Mei Liu
Keyword(s):  
Finite Element ◽  
Wire Bonding ◽  
Bonding Process ◽  
Ultrasonic Frequency ◽  
Element Analysis ◽  
Mems Accelerometer ◽  
Finite Element Software ◽  
Wire Bond ◽  
Ball Bonding ◽  
The Wire

The wire bonding process in the package of MEMS accelerometer is analyzed by the finite element software ANSYS/LS-DYNA. Impact on the bonding strength of the ultrasonic amplitude, ultrasonic frequency and the friction between wire bond and bond pad are studied. The strength of wire bond is evaluated through the bond pull test experiment. The test result shows that the analysis on the wire bonding is helpful for improving the quality of wire bonding.

scholarly journals Stitch Bond Process of Pd-Coated Cu Wire: Experimental and Numerical Studies of Process Parameters and Materials

2013 ◽  
Vol 2013 (1) ◽  
pp. 000312-000317 ◽  
Author(s):  
A. Rezvani ◽  
M. Mayer ◽  
I. Qin ◽  
J. Brunner ◽  
Bob Chylak
Keyword(s):  
Process Parameters ◽  
Surface Finish ◽  
Cost Reduction ◽  
Wire Bonding ◽  
Process Window ◽  
Capillary Surface ◽  
Bond Force ◽  
Short Tail ◽  
Surface Finishes ◽  
The Wire

Cost reduction is the main driver in the recent transition to Cu wire bonding from predominate Au wire bonding. Other cost reduction in packaging comes from new developments in substrates and lead frames, for example, Pre-Plated Frames (PPF) and uPPF for QFP and QFN reduce the plating and material cost. However, 2nd bonds (stitch bonds) can be more challenging on some of the new leadframe types due to the rough surface finish and thin plating thickness. Pd-coated Cu (PCC) wire has been recently introduced to improve the wire bonding process with bare Cu wire, mainly to improve reliability and enhance the stitch bond process. More fundamental studies are required to understand the influences of bonding parameters and bonding tools to improve stitch bondability. The stitch bond process of 0.7 mil diameter PCC wire on Au/Ni/Pd-plated quad flat-no lead (QFN) PPF substrate is investigated in this study. Two capillaries with the same geometry but different surface finishes are used to investigate the effect of capillary surface finish on the stitch bond process. The two capillary types are a polished finish type which is commonly used for Au wire bonding, and a granular finish capillary that has a much rougher surface finish. Process window between no stick on lead (NSOL) and short tail is compared. The effect of process parameters including bond force and table scrub amplitude is studied. The process window test results revealed that the granular capillary has larger process window and a lower chance of short tail occurrence. It has been shown that a higher scrub amplitude increases the chance of successful stitch bond formation. To further compare the capillary surface finishes, 3 sets of parameter settings with different bond force and scrub amplitude are tested. For all three parameter sets tested, the granular capillary showed better quality in bond strength. The granular capillary resulted in higher stitch pull strength compared to the polished type. A finite element model (FEM) of the process was developed to better understand the experimental observations. The amount of surface expansion (plastic deformation) of the wire at the wire and substrate interface was extracted from the model and attributed to the degree of adhesion (bonding). The model was used to confirm the experimental observation of adhesion (bonding) with different surface finish.

Comparison of Fundamental Frequency and Sweep Resistance of Different Wire Loops Using Finite Element Model

2015 ◽  
Vol 15 (01) ◽  
pp. 1450032 ◽  
Author(s):  
Yun Chen ◽  
Fuliang Wang
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
High Speed ◽  
Element Model ◽  
Microelectronic Packaging ◽  
Fe Model ◽  
Wire Loop ◽  
Loop Design ◽  
Loop Shape ◽  
The Wire

Wire loop resistance is critical for microelectronic packaging because it directly influences the reliability of the product. Proposed herein is an effective method for predicting the resistance of a wire loop. A finite element (FE) model is developed for verifying the method. The wire geometry is modeled based on actual wire profiles captured with a high-speed camera. Based on this model, the effects of wire properties, residual stresses, loop shape and loop type on the wire loop resistance are studied. Simulations demonstrated that the shape of the loop could dramatically alter the wire loop resistance. On the other hand, the wire properties, residual stresses and loop type mildly affect the wire loop resistance. The standard loop is the more resistant loop than the N and M loops. By using a large and hard wire, moderately tensioning the wire loop and reducing the loop span, height and number of kinks, one can improve the wire loop resistance. This study should provide useful insights into loop design for modern microelectronic packaging.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

scholarly journals Influence of finite element mesh size on the carrying capacity analysis of single-row ball slewing bearing

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110090
Author(s):  
Peiyu He ◽  
Qinrong Qian ◽  
Yun Wang ◽  
Hong Liu ◽  
Erkuo Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Carrying Capacity ◽  
Mesh Size ◽  
Finite Element Mesh ◽  
Fe Model ◽  
Element Mesh ◽  
Heavy Load ◽  
Slewing Bearing ◽  
Maximum Contact ◽  
Slewing Bearings

Slewing bearings are widely used in industry to provide rotary support and carry heavy load. The load-carrying capacity is one of the most important features of a slewing bearing, and needs to be calculated cautiously. This paper investigates the effect of mesh size on the finite element (FE) analysis of the carrying capacity of slewing bearings. A local finite element contact model of the slewing bearing is firstly established, and verified using Hertz contact theory. The optimal mesh size of finite element model under specified loads is determined by analyzing the maximum contact stress and the contact area. The overall FE model of the slewing bearing is established and strain tests were performed to verify the FE results. The effect of mesh size on the carrying capacity of the slewing bearing is investigated by analyzing the maximum contact load, deformation, and load distribution. This study of finite element mesh size verification provides an important guidance for the accuracy and efficiency of carrying capacity of slewing bearings.

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