An analytical approach to bga components in random vibration

Report
AN ANALYTICAL APPROACH
TO BGA COMPONENTS IN
RANDOM VIBRATION
ENVIRONMENTS
Milan J Lucic, MANE 6980 Engineering Project
Methodology and Approach

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Accurately model the ACTEL 484 PBGA with 3-D hex
elements (balls and solder joint), and 2-D Shell elements
(PCB and component body)
Using NX7.5 Advanced simulation for Pre-Processing and
MSC PATRAN/MD NASTRAN as the post processor and
solver
PATRAN Random utility to solve for frequency response
(Mode Shapes), displacements, and RMS stresses
PATRAN static inertial analysis to solve for stresses of BGA’s


Greatly reduce analysis time!
Using hand calculations, solve for the Miner’s Damage Index
of electrical components and the high cycle fatigue of the
BGA components.
Expected Outcomes


To develop a better understanding of lead vs. lead
free BGA components used in common Aerospace
environments
Correlate data with actual industry test data to
refine future models
 Greatly
reduce risks early in the design phase
 Eliminate the need for development testing of BGA
components (expensive and time consuming)

Generate plots of high cycle fatigue life for lead
vs. lead-free BGA components
Project Progress-FEA Model
Pin Grid
Snapshot
BGA Model
ACTEL 484 PGA
Solder Ball and
Solder Joint FEM
Project Progress-FEA Model
Boundary Conditions:
Interconnect
Fixed Edge (6DOF) (Card Guide)
Connectors
b
a
Fixed Edge (6DOF) (Card Guide)
Fixed Edge (6DOF)
Free Edge
a
Finite Element Analysis-Hand Calcs
E * h3
D
12* (1   2 )
Plate Stiffness Factor
First Mode Natural Frequency
 D .75 2 12 
f n     4  2 2  4 
a
3 
a b b 
GRMS
G

Single Amplitude Displacement

Z RMS

2
* P * Q* f n
9.81* G

fn2
Curve C Calculated Results:
fn =266.4 Hz
ZRMS = .0018 inches
Finite Element Analysis-Normal Modes
Mode 1: 266.59 Hz
Mode 2: 341.07 Hz
Mode 3: 511.18 Hz
Finite Element Analysis-Random
Mode 1
Mode 2
Input Curve
Frequency Response
RMS Displacement
Mode 3
Finite Element Analysis-Optimization
Optimized Size: 570 Elements (Quad 20)
Project Schedule
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Week 1: Develop Project Definition
Week 2: Preliminary Project Proposal
Week 3: Project Proposal
Week 4: FEA Model Development/Research
Week 5: Random Analysis/Model Refinement
Week 6: Random Analysis/Model Optimization
Week 7: Random Analysis/Model Optimization, First Progress Report
Week 8: MDI Calculations/Random Analysis
Week 9: Inertial Analysis
Week 10: Post Processing, Second Progress Report
Week 11: Post Processing (extra time for model refinement)
Week 12: Final Report Draft
Week 13: Final Report Draft
Week 14: Final Report

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