Characterization and Modeling of Printed Wiring Board Warpage and its Effect on LGA Separable Interconnects

2004 ◽  
Vol 127 (2) ◽  
pp. 178-184 ◽  
Author(s):  
J. Cepeda-Rizo ◽  
Hsien-Yang Yeh ◽  
N. Teneketges
Keyword(s):  
Printed Wiring Board ◽  
Out Of Plane ◽  
Mechanical Fastening ◽  
Laminate Theory ◽  
Wiring Board ◽  
Plane Displacement

The paper presents a study on printed wiring board (PWB) warpage caused by the mechanical fastening of separable interconnects, known as land grid array (LGA) package assemblies. Out-of-plane displacement of the PWB were measured and characterized, as well as force-per-pin values of the LGA, and correlations were made between the two. Classical laminate theory was utilized to describe the warpage behavior of the assembly and a model was presented to solve the out-of-plane displacements. An overall assessment of the assembly was made and compared to the mechanical specification of the LGA.

Warpage Measurement Using Projection Moire´ System and Two Automatic Image Segmentation Algorithms

2007 ◽  
Author(s):  
Wei Tan ◽  
I. Charles Ume
Keyword(s):  
Image Segmentation ◽  
Electronic Packages ◽  
Printed Wiring Board ◽  
Segmentation Algorithms ◽  
Out Of Plane ◽  
Cte Mismatch ◽  
Image Models ◽  
Wiring Board ◽  
Plane Displacement ◽  
Projection Moire

Out-of-plane displacement (warpage) has been a major reliability concern for board-level electronic packaging. Printed wiring board (PWB) and component warpage results from CTE mismatch among the materials that make up the PWB assembly (PWBA). Warpage occurring during surface-mount assembly reflow processes and normal operations may lead to serious reliability problems. In this paper, a projection moire´ warpage measurement system and two types of automatic image segmentation algorithms were presented. In order to use the projection moire´ technique to separately determine the warpage of a PWB and assembled electronic packages in a PWBA, two image segmentation algorithms based on mask image models and active contour models (snakes) were developed. They were used to detect package locations in a PWBA displacement image generated by the projection moire´ system. The performances of the mask image and snake approaches based on their resolutions, processing rates, and measurement efficiencies were evaluated in this research. Real-time composite Hermite surface models were constructed to estimate the PWB warpage values underneath the electronic packages. The above automatic image segmentation algorithms were integrated with the projection moire´ system to accurately evaluate the warpage of PWBs and assembled chip packages individually.

Nonlinear Dynamics Analysis of a Laminated Printed Wiring Board

2002 ◽  
Vol 124 (2) ◽  
pp. 77-84 ◽  
Author(s):  
Xiaoling He ◽  
Robert E. Fulton
Keyword(s):  
Dynamic Response ◽  
Large Deflection ◽  
Equations Of Motion ◽  
Response Analysis ◽  
Printed Wiring Board ◽  
High Acceleration ◽  
Dynamic Stress Field ◽  
Laminate Theory ◽  
Wiring Board ◽  
Nonlinear Elastic

Nonlinear laminate theory is applied for the printed wiring board (PWB) dynamic response analysis. Equations of motion for the nonlinear elastic deformation of the isotropic laminates are derived for the dynamic response of a simply supported PWB. Numerical results are generated for the nonlinear response characterization of the PWB deformation. Comparisons are made between the response of linear and nonlinear systems. Results show that PWB is in large deflection under high acceleration or certain pressure load. Nonlinear theory gives more accurate results for the large deflection than the linear theory does. Besides, lamina stresses are analyzed and illustrated from finite difference computation. The analytical derivation in modal approach and the stress analysis provide the basis for PWB reliability studies, especially the defect and failure induced by the dynamic stress field.

Comparison of Electronic Component Durability Under Uniaxial and Multiaxial Random Vibrations

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Matthew Ernst ◽  
Ed Habtour ◽  
Abhijit Dasgupta ◽  
Michael Pohland ◽  
Mark Robeson ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Failure Modes ◽  
Accumulation Rate ◽  
Center Of Mass ◽  
Dynamic Environment ◽  
Test Method ◽  
Printed Wiring Board ◽  
Uniaxial Testing ◽  
Out Of Plane ◽  
Wiring Board

Multiaxial and uniaxial vibration experiments were conducted in order to study the differences in failure modes and fatigue life for the two types of excitation. An electrodynamic (ED) shaker capable of controlled vibration in six degrees of freedom (DOF) was employed for the experiments. The test specimen consisted of six large inductors insertion mounted on a printed wiring board (PWB). Average damage accumulation rate (DAR) in the inductor leads was measured for random excitations in-plane, out-of-plane, and both directions simultaneously. Under simultaneous multiaxial excitation, the average DAR was found to be 2.2 times greater than the sum of the in-plane and out-of-plane DARs. The conclusion was that multiple-step sequential uniaxial testing may significantly overestimate the durability of large/heavy structures with high center of mass in a multiaxial dynamic environment. Additionally, a test method utilizing uniaxial vibration along a direction other than the principal directions of the structure was examined. This method was found to have significant limitations, but showed better agreement with simultaneous multiaxial vibration experiments.

Creep Prediction of a Printed Wiring Board For Separable Land Grid Array Connector

2004 ◽  
Vol 127 (2) ◽  
pp. 185-188
Author(s):  
J. Cepeda-Rizo ◽  
Hsien-Yang Yeh
Keyword(s):  
Creep Behavior ◽  
Low Cost ◽  
Polymeric Materials ◽  
Superposition Method ◽  
Printed Wiring Board ◽  
Three Point Bending ◽  
Testing Method ◽  
Temperature Superposition ◽  
Mechanical Fastening ◽  
Wiring Board

The paper presents a study of creep behavior of a printed wiring board caused by the mechanical fastening of separable connector, known as a land grid array. Time-temperature superposition method was employed to predict the lifetime creep behavior. A low-cost testing method based on the ASTM D790 three-point bending procedure was developed to predict and characterize creep of polymeric materials under low temperature, low stress, and large elapsed times.

Nonlinear Thermal and Mechanical Analysis in the Vibration of a Printed Wiring Board

2000 ◽  
Author(s):  
Xiaoling He ◽  
Robert Fulton
Keyword(s):  
Dynamic Analysis ◽  
Modal Analysis ◽  
Temperature Variation ◽  
Equations Of Motion ◽  
Mechanical Analysis ◽  
Response Analysis ◽  
Printed Wiring Board ◽  
Simply Supported ◽  
Laminate Theory ◽  
Wiring Board

Abstract Nonlinear laminate theory is applied and extended for the printed wiring board dynamic analysis. Equations of motion for the isotropic laminates are derived for vibration response analysis of the simply supported printed wiring board under mechanical and thermal loads. Temperature variation in spatial domain is taken into consideration. The effect of the temperature variation on the response character is analyzed and demonstrated by means of numerical results. Modal analysis is made to predict the vibration behavior in terms of deflection and stresses. Lamina stresses are used for failure prediction.

scholarly journals Sensor Integrated Load-Bearing Structures: Measuring Axis Extension with DIC-Based Transducers

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4104
Author(s):  
Nassr Al-Baradoni ◽  
Peter Groche
Keyword(s):  
Cost Effective ◽  
Image Correlation ◽  
Maximum Deviation ◽  
Single Image ◽  
Eccentric Load ◽  
Load Bearing ◽  
Out Of Plane ◽  
Axis Extension ◽  
Plane Displacement ◽  
Imaging Sensor

In this paper we present a novel, cost-effective camera-based multi-axis force/torque sensor concept for integration into metallic load-bearing structures. A two-part pattern consisting of a directly incident and mirrored light beam is projected onto the imaging sensor surface. This allows the capturing of 3D displacements, occurring due to structure deformation under load in a single image. The displacement of defined features in size and position can be accurately analyzed and determined through digital image correlation (DIC). Validation on a prototype shows good accuracy of the measurement and a unique identification of all in- and out-of-plane displacement components under multiaxial load. Measurements show a maximum deviation related to the maximum measured values between 2.5% and 4.8% for uniaxial loads ( and between 2.5% and 10.43% for combined bending, torsion and axial load. In the course of the investigations, the measurement inaccuracy was partly attributed to the joint used between the sensor parts and the structure as well as to eccentric load.

scholarly journals Locally Corroded Stiffener Effect on Shear Buckling Behaviors of Web Panel in the Plate Girder

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Jungwon Huh ◽  
In-Tae Kim ◽  
Jin-Hee Ahn
Keyword(s):  
Corrosion Damage ◽  
Element Analysis ◽  
Buckling Strength ◽  
Lower Shear ◽  
Out Of Plane ◽  
Shear Buckling ◽  
Buckling Failure ◽  
Plane Displacement ◽  
The Web ◽  
Plate Girder

The shear buckling failure and strength of a web panel stiffened by stiffeners with corrosion damage were examined according to the degree of corrosion of the stiffeners, using the finite element analysis method. For this purpose, a plate girder with a four-panel web girder stiffened by vertical and longitudinal stiffeners was selected, and its deformable behaviors and the principal stress distribution of the web panel at the shear buckling strength of the web were compared after their post-shear buckling behaviors, as well as their out-of-plane displacement, to evaluate the effect of the stiffener in the web panel on the shear buckling failure. Their critical shear buckling load and shear buckling strength were also examined. The FE analyses showed that their typical shear buckling failures were affected by the structural relationship between the web panel and each stiffener in the plate girder, to resist shear buckling of the web panel. Their critical shear buckling loads decreased from 82% to 59%, and their shear buckling strength decreased from 88% to 76%, due to the effect of corrosion of the stiffeners on their shear buckling behavior. Thus, especially in cases with over 40% corrosion damage of the vertical stiffener, they can have lower shear buckling strength than their design level.

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