Plastic Strain Based Criterion for Reliability Assessment of CSP Packages Subjected to Dynamic Shock Loads

2005 ◽  
Author(s):  
Liping Zhu ◽  
Rick Williams
Keyword(s):  
Plastic Strain ◽  
Solder Joint ◽  
Failure Modes ◽  
Mechanical Load ◽  
Failure Criteria ◽  
Dynamic Responses ◽  
Finite Element Software ◽  
Bga Package ◽  
Shock Event ◽  
Reliability Performance

Drop impact induced crack in ball grid array (BGA) solder joint is one of the most dominant failure modes found in BGA package under mechanical load. The failure in BGA due to its excess stress resulting from over bended deformation in a PCB board during shock event is not only a function of solder material but a board and package structure as well. Due to extremely difficult and infeasible in directly measuring responses in BGA solder joint during drop shock event, computer modeling approach has been increasingly played an important role in evaluating product reliability performance during product development. Modeling technique with a comprehensive failure criterion and metric including high strain rate effect is necessary to be developed to quantitatively evaluate and benchmark BGA package reliability performance for different board designs. In this paper, dynamic responses in CSP/BGA in different boards and product phone have been characterized by using nonlinear dynamic finite element software, LS-Dyna. Different failure criteria, such as plastic strain and stress based are investigated and compared. It is shown that a good correlation between validation test and numerical result can be achieved by using proposed plastic strain based criterion only and thus it can be used in cross comparisons between different board designs.

Finite Element Analysis of X-Cor Sandwich's Compressive Strength

2011 ◽  
Vol 306-307 ◽  
pp. 733-737
Author(s):  
Xu Dan Dang ◽  
Xin Li Wang ◽  
Hong Song Zhang ◽  
Jun Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compressive Strength ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Element Model ◽  
Failure Criteria ◽  
Stiffness Degradation ◽  
Element Analysis ◽  
Finite Element Software

In this article the finite element software was used to analyse the values for compressive strength of X-cor sandwich. During the analysis, the failure criteria and materials stiffness degradation rules of failure mechanisms were proposed. The failure processes and failure modes were also clarified. In the finite element model we used the distributions of failure elements to simulate the failure processes. Meanwhile the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates that the resin regions of Z-pin tips fail firstly and the Z-pins fail secondly. The dominant failure mode is the Z-pin elastic buckling and the propagation paths of failure elements are dispersive. Through contrast the finite element values and test results are consistent well and the error range is -7.6%~9.5%. Therefore the failure criteria and stiffness degradation rules are reasonable and the model can be used to predict the compressive strength of X-cor sandwich.

ORTHOTROPIC DAMAGE MODEL USING TSAI-WU FAILURE CRITERIA

2021 ◽  
Author(s):  
M. R. T. ARRUDA ◽  
L. ALMEIDA-FERNANDES, ◽  
L. CASTRO ◽  
J. R. CORREIA
Keyword(s):  
Failure Modes ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Damage Model ◽  
Failure Criteria ◽  
Simple Method ◽  
Finite Element Software ◽  
User Subroutine ◽  
Novel Approach ◽  
The Moment

This paper presents a novel approach concerning the development of an orthotropic damage model, based on the original plane Tsai-Wu failure criteria. In its original formulation, the Tsai-Wu is a mode independent criterion only capable of acknowledging the existence of damage in a certain point of the material. It is not capable of identifying if the damage is located in the fiber, matrix or intralaminar zone. This work plans to fill this gap in knowledge by providing a simple method, based on equivalent stress and strains, that identifies the failure modes when the Tsai-Wu failure criteria is near the on-set of damage. Using this novel method, it is possible to implement classical damage evolutions constitutive laws based on the MTL formulation. At the moment the proposed damage formulation is based on plane stress space and Mode I fracture, but it is expected in the future to evolve in to a full 3D damage model. The damage model is implemented in the commercial finite element software ABAQUS using user-subroutine UMAT, and all numerical models are compared with the experimental results.

Emerging Flux Challenges for BGA Packages

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 001359-001390
Author(s):  
Maria Durham ◽  
Andy Mackie ◽  
Jason Chou
Keyword(s):  
Solder Joint ◽  
Failure Modes ◽  
Value Added ◽  
Ball Grid Array ◽  
Deposition Process ◽  
Testing Methods ◽  
Bga Packages ◽  
Bga Package ◽  
One Step ◽  
Process Cost

The formation of a Ball Grid Array (BGA) solder joint is critical for a BGA package where typically a flux deposition process is used. Reflowing solder spheres to solderable pads on the bottom of substrates in standard BGA, FCBGA, CSP, and similar packages is considered to be a trivial step: a specialized BGA flux is usually pin-transferred onto the pads, followed by balldrop onto the substrate. However, with the increasing complexity and number of assembly processes taken prior to this final step, the formation of a reliable final joint is far from certain. In order to eliminate variability, many OSATs and ODMs use the so-called “two step” (double fluxing) approach, which is comprised of the non-value-added extra processes of prefluxing, reflowing, cleaning, and drying substrates immediately prior to the final flux-based ball-attach process. This paper details the sequence of processes seen in typical FCBGA assembly, and examines the effects of each set of prior processes on the solderability of the final pad. The introduction of a “one-step” pin-transfer ball-attach flux is shown to be a means of reducing both process cost and time, and also reducing the risk of increased warpage in the finished package. The paper also investigates the solderable surface and metallurgy of the substrate pad. The variety of new and emerging failure modes for the BGA process as well as the different testing methods for the materials will also be discussed.

Study on Dynamic Responses and Reinforcement of Reinforced Concrete Columns Subjected to Blast Loading

2015 ◽  
Vol 744-746 ◽  
pp. 315-318
Author(s):  
Hao Du ◽  
Chun Hua Liu
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Blast Loading ◽  
Concrete Columns ◽  
Dynamic Responses ◽  
Stress And Strain ◽  
Reinforced Concrete Columns ◽  
Finite Element Software ◽  
Regional Conflicts ◽  
Blast Resistant Design

The terrorism and regional conflicts posed a threat to the world peace. Some terrorist explosions caused collapse of the buildings, which brought heavy tragedies to the human components. Therefore research on damage of structural components and resistance to damage have become the focus of our attention. Finite element software LS-DYNA was applied to simulating the response of reinforced concrete columns under blast loading. And analysis on dynamic response under different loading period was carried out. By studying on the stress and strain of reinforced concrete columns subjected to blast loading, the possible failure modes were obtained. In addition, the bearing capacities of concrete columns that are reinforced with carbon fiber and steel panel were analyzed, and the reinforcement effects were compared to provide reasonable reinforcement schemes for structures blast-resistant design.

Global Characterization of Failure Modes Under Impact Loading in Structural Components Made of Low Ductility Materials

2001 ◽  
Author(s):  
Shen Rong Wu ◽  
Xiaoming Chen ◽  
Weiran Hu
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Failure Process ◽  
Failure Criteria ◽  
Tensile Failure ◽  
Forming Limit ◽  
Structural Components ◽  
Explicit Finite Element ◽  
Finite Element Software ◽  
The Impact

Abstract This study reviews the impact failure modes of structural components made of materials with low ductility such as aluminum and magnesium. Tensile failure is observed at large stretch area or on the tension side of large bending deformation. Material breakage due to shear may also occur. There are several approaches to simulate the material failure process in explicit finite element software used for crashworthiness analysis. Evaluation of the effective applications of these material models is presented with a finite element simulation of bi-axial loading tests. The forming limit diagram is used to evaluate various failure criteria. Component crash simulations are presented to demonstrate the applications of failure criteria.

Failure Analysis of Composite Structures Using Multiscale Technique

2020 ◽  
Vol 995 ◽  
pp. 209-213
Author(s):  
Young W. Kwon
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Cell Model ◽  
Fibrous Composite ◽  
Failure Criteria ◽  
Multiscale Approach ◽  
Interface Failure ◽  
Fiber Failure ◽  
Strain Rate Effects ◽  
Constituent Material

Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.

Numerical Model to Simulate the Drop Test of Printed Circuit Board (PCB)

2011 ◽  
Vol 423 ◽  
pp. 26-30
Author(s):  
S. Assif ◽  
M. Agouzoul ◽  
A. El Hami ◽  
O. Bendaou ◽  
Y. Gbati
Keyword(s):  
Solder Joint ◽  
Printed Circuit Board ◽  
Drop Test ◽  
Dynamic Responses ◽  
Circuit Board ◽  
Joint Stress ◽  
Printed Circuit ◽  
Increasing Demand ◽  
Improved Model ◽  
Board Level

Increasing demand for smaller consumer electronic devices with multi-function capabilities has driven the packaging architectures trends for the finer-pitch interconnects, thus increasing chances of their failures. A simulation of the Board Level Drop-Test according to JEDEC (Joint Electron Device Council) is performed to evaluate the solder joint reliability under drop impact test. After good insights to the physics of the problem, the results of the numerical analysis on a simple Euler-Bernoulli beam were validated against analytical analysis. Since the simulation has to be performed on ANSYS Mechanical which is an implicit software, two methods were proposed, the acceleration-input and the displacement-input. The results are the same for both methods. Therefore, the simulation is carried on the real standard model construction of the board package level2. Then a new improved model is proposed to satisfy shape regular element and accuracy. All the models are validated to show excellent first level correlation on the dynamic responses of Printed Circuit Board, and second level correlation on solder joint stress. Then a static model useful for quick design analysis and optimization’s works is proposed and validated. Finally, plasticity behavior is introduced on the solder ball and a non-linear analysis is performed.

Predicting Plastic Flow Behaviour, Failure Mechanisms and Severe Deformation Localisation of Dual-Phase Steel using RVE Simulation

2021 ◽  
Vol 18 (1) ◽  
pp. 8601-8611
Author(s):  
A. K. Rana ◽  
P. P. Dey
Keyword(s):  
Plastic Strain ◽  
Failure Modes ◽  
Volume Fraction ◽  
Ferrite Matrix ◽  
Martensite Phase ◽  
Von Mises Stress ◽  
Dual Phase ◽  
Strain Partitioning ◽  
Deformation Inhomogeneity ◽  
Von Mises

In this work, the von Mises stress and plastic strain distribution of Ferrite-Martensite–Dual-Phase (FMDP) steels are predicted at various stages of deformation. The failure modes and volume fraction effect are identified based on Representative Volume Element (RVE). FMDP steel consists of a typical ferrite-matrix phase, in which martensite-islands are dispersed. Recently FMDP steels are increasingly used to the various car parts in demand. 2D-RVEs are also utilised to predict the orientations effect of the martensite phase in the FMDP steels. Based on the position of the element, the boundary conditions (BC) are given in the RVE of FMDP steel microstructures. The failure modes are examined in the form of severe plastic strain localisation. While the distribution of islands in the microstructure varies, as a result, the deformation inhomogeneity increases with a rise of martensite fraction. The results of numerical computation and the trend of experimental failure shown in the literature are compared. This is signifying that the overall macro-behaviour of FMDP steel, as a consequence of stress-strain partitioning and influence of martensite-island volume fractions (MVFs), can be predicted by the finite element (FE) based 2D-RVE modelling.

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