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Transcript of CALCE Simulation Assisted Reliability Assessment … · University of Maryland Copyright © 2018...
![Page 1: CALCE Simulation Assisted Reliability Assessment … · University of Maryland Copyright © 2018 CALCE Center of Advanced Life Cycle Engineering 22 Cooling Modes modeled in calcePWA](https://reader031.fdocuments.us/reader031/viewer/2022013117/5b90f24209d3f2857e8d0fcc/html5/thumbnails/1.jpg)
University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 1http://www.calce.umd.edu
CALCE Simulation Assisted Reliability Assessment (SARATM) Software
http://www.calce.umd.edu/software/
Michael OstermanCALCE Electronic Products and Systems Center
University of MarylandCollege Park, Maryland 20742
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 2http://www.calce.umd.edu
Thermal AnalysisVibrational Analysis
Shock AnalysisFailure Analysis
calcePWACircuit Card Assemblies Failure Analysis
calceEPDevice andPackage
calceFASTFailure Assessment
Software Toolkit
http://www.calce.umd.edu/software
CALCE Simulation Assisted Reliability Assessment (SARA®) Software
Conductor II
Conductor I
Whisker
Spacing (ls)
calceTinWhisker FailureRiskCalculator
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 3http://www.calce.umd.edu
Virtual QualificationDesign Capture
Loa
d
Time to Failure
Ranking of Potential Failure Sites and Mechanisms
Field1
2 3
Life-Cycle Loads
Load Transformation
Failure Quantification
Physical Verification: Test Setup, Specimen Characterization, Accelerated Stress Test
Simulation Assisted Reliability Assessment
Failure Risk Identification
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 4http://www.calce.umd.edu
Uses of Virtual Qualification
• Life assessment under anticipated loading conditions• Design trade-offs• Accelerated test planning• Interpretation of accelerated test results with respect
to field life• Remaining life assessment• Prognostics development
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 5http://www.calce.umd.edu
Testing Results:
Analysis Results:• 20 pin Leadless Chip Carrier (LCC) was weak in design• Estimated life under operating conditions - 6.5 years
Objectives:
• Assess reliability of ControlModule in the military environment
• Improve reliability of ControlModule
• Module Level - 5,000 units fielded - 20 years field life
117
121
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124
125
131
132
151
202
206
0 500 1000 1500 2000
LCC Failure Model predictionModule Timeline 20 Year life
20 Y
ear L
ife
Mod
el P
redi
ctio
n
Developed Log Case Studyfor Potential Improvements
Testing of CCAs demonstrated failures predicted by CalcePWA Analysis. Redesign of module results in an estimated savings of
$27 mil in avoided cost.
Aluminum BackplaneBoard 1
Board 2
Board 3
Frame
Aluminum Backplane
CalcePWA Software Assessment (Military Radio)
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 6http://www.calce.umd.edu
• Product development using simulations produced a more robust design, faster
• First pass issue reductions: 100% E/E circuits, 83% permanent failures, 75% EMI, 63% total
• The more complex module using the simulated assisted design achieved higher quality durability and reliability by beta version in a faster period.
Successful Application of calceSARADesign-Build-Test-Fix vs. Simulation Assisted Design
Program Comparison:E/E Technology:Functional/Software Complexity:Power/Internal Heat:Packaging:Supplier:
Results:# of Total Test Issues Identified::
ModerateProven Tech/Compts - No Electromech.
ModerateLow Power/Heat
I.P. Mounted Snap Fit, 1 conn.Supplier A - Highly Capable
Completed 1/9816
(Development Period - 130 Wks) (Development Period - 109 Wks)More Complex
Proven Tech/Compts+4 Onboard RelaysMore Functions, More Complex
High Power & Thermal ChallengesConsole Mnt., Integt’d w/Fuse (NEW)
Supplier A - Highly Capable
Completed 8/996
PontiacGrand Am
PontiacAztek
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 7http://www.calce.umd.edu
Comanche• Commonality w/ AF F-22• Commercial ICs Inserted• $50M O&S savings
Bradley Fire Support Vehicle• Identified potential problems• Increased Reliability
Life Cycle PoF Analysis Provides Considerable ROI
Applications of CALCE SoftwareSeagate •Virtual Qualification
Emerson•Virtual Qualification of CCA•Failure assessment of a individual component.
Mars Path FinderVerified robustness of flight CCA
AAAVVirtual Qualificationof circuit cards
VISTA ControlsConducted virtualqualification of militaryCCA
CPU CardMezzanine Card
Assembly
JSTARS Ground Station• PoF Analysis on circuit cards• Recommended commercial
processor circuit card• $12M Savings
GM83% reduction in design issues>10% reduction in time to markert
HoneywellVirtual qualification of enginecontroller
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 8http://www.calce.umd.edu
Testing and development is conducted primarily on a system with a 2.3 GHz i5-5300U, 8 GB, Windows 7
• Platforms– x86-32, x86-64 Hardware
• Windows 10, Window 8, or Windows 7• Disk Space and Memory
• 233 MB recommended• 2 GB recommended
System Requirements for CALCE SARA® Software
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 9http://www.calce.umd.edu
https://calce.umd.edu/calce-sara-software
CalceSARA can be downloaded from the CALCE Web Site. The web site provides software, user’s manuals, installation instructions, past workshop materials, and other software documentation. Software is updated approximately every four months.
CALCE Software Web Site
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 10http://www.calce.umd.edu
The installation of calceSARA 8.0 is facilitated by installation software that takes you step-by-step through the software installation procedure.
Installation of calceSARA Release 8.0
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 11http://www.calce.umd.edu
The calceSARA applications are launched like any other Windows application, by selecting the desired application from the list of available tools under calceSARA folder.
CalcePWA, calceFAST, calceEP, and calceWhiskerRiskCalculator, the CALCE Software Update application, and the user documentation can all be launch from the Start Menu.
Starting calceSARA 8.0
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 12http://www.calce.umd.edu
CalceTCExtractor
The TC Extractor is used to cover temperature time history into discrete half temperature cycles and reduced half cycles.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 13http://www.calce.umd.edu
TC Extracted Data Uses
Temperature cycles extracted using the calceTCExtractor can be used in calcePWA, calceFAST, and calceEP.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 14http://www.calce.umd.edu
PWA Failure Assessment SoftwarecalcePWA 8.0
Design CaptureInterface to CAD
Assessment Management
Stress Assessment
Life CycleCharacterization
Life Expectancy andFailure Assessment
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 15http://www.calce.umd.edu
calcePWA VQ InputsProduct Construction Information• Bill of Materials (BOM) – Parts list with manufacturer and manufacture part
number sufficient to obtain mechanical package information for the assembly under review.
• Part layout (x,y, orientation) on the printed wiring assembly may be imported from a CAD intermediate file for the assembly under review.
• Board thickness and material lay-up• Solder stencil thickness and solder material• Mechanical support positions on the printed wiring board
Operational and Usage Information• Operating power of parts within the assembly. • Expected thermal management of the printed wiring assembly.• Life expectancy of the assembly under review• Expected operational temperature cycling
– Maximum temperature– Minimum temperature
• Expected vibration loading– Defined PSD normal to the surface of the printed wiring board
• Operation voltage levels of electrolytic capacitors
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 16http://www.calce.umd.edu
CALCE VQ Outputs• Steady State Board and Component Temperatures• Mode Shapes, Natural Frequencies, Displacement
Response to Random Vibration and Shock Loading• Time to Failure of
– Package to board interconnects due to temperature cycle and vibration loading
– PTH under temperature cycle loading– Electrolytic Capacitors under steady voltage and temperature
operation (calceFAST)• Probability of failure of
– Package to board interconnects due to shock loading– MLCC under mechanical bending (calceFAST)
• Acceleration Factors between specified test and life conditions.
• Equivalent Life Time for a specified test.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 17http://www.calce.umd.edu
Managing the CCA Virtual Qualification Process
Status of the calcePWA
evaluation process can be quickly
viewed in this panel.
Modeling
Reliability Assessment
Stress Assessment
Thumbnail images of CCA
CCA Selection Tab
Project Selection Bar
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 18http://www.calce.umd.edu
calcePWA Libraries
To promote reuse of data, the calcePWA software has the following database libraries. Libraries can be build either top down and bottom up.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 19http://www.calce.umd.edu
Printed Wiring Assembly Design Manager
The PWA design manager provides the ability to define and/or modify the PWA model. Model items include board outline, material inserts, layer stack-up, vias, component, part, and materials.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 20http://www.calce.umd.edu
Supported CAD Text File Imports
• ODB++• P-CAD• Veribest• GENCAD 1.4• Mentor Neutral File• Cadance IDF file• PADS 1.0, 3.5, 4.0 text files• Zuken-Recal (CADIF) text files
Import currently available for
Import typically provides board outline, part list, component list, and component positions referenced to the board outline. The import procedure was developed by extracting data from example text files.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 21http://www.calce.umd.edu
Thermal Assessment
Boundaryconditions are appliedto each layer
UnassignedGrid Locationsare calculated
BoundaryConditionSelection
Palette
Flood Fill Toggle Button allows for rapid assignment of boundary conditions at the edge of the board
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 22http://www.calce.umd.edu
Cooling Modes modeled in calcePWACooling Mode Description
Conduction Internal conduction only
Conduct_VC Internal conduction, natural convection with assumed vertical orientation.
Conduct_VC_Rad Internal conduction, natural convection with assumed vertical orientation with surface radiation.
Flowover Internal conduction, surface convection based on defined air flow.
Conduct_HC Internal conduction, natural convection with assumed horizontal orientation, venting of air assumed.
Conduct_HCNV Internal conduction, natural convection with assumed horizontal orientation, no venting of air assumed.
Conduct_Rad Internal conduction, surface radiation to enclosure.
Conduct_HC_Rad Internal conduction, surface radiation to enclosure, natural convection with assumed horizontal orientation, venting of air assumed.
Conduct_HCNV_Rad Internal conduction, surface radiation to enclosure, natural convection with assumed horizontal orientation, no venting of air assumed.
ColdPlate Fin Structure Required. Internal conduction. Internal convection to Air in defined fin structure.
Coldplate_with_NC Fin Structure Required. Internal conduction. Internal convection to Air in defined fin structure. Natural convection with assumed vertical orientation.
( * Natural Convection is assumed to occur in the y direction (bottom to top as board appears on the screen)
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 23http://www.calce.umd.edu
Tabular view of component information
Cross-Section Plot
Display of Thermal Analysis Results
CalcePWA ThermalDisplay Toolpresents theresults of a thermalanalysis.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 24http://www.calce.umd.edu
Determining Component Temperatures
T T QRsub layer z
Tlayer -- Layer temperature below component
Ac -- Planar component area
Rz -- 05. ZK Az c
T T Q Rcase sub case
Rcase -- Parallel resistance of leads and case to substrate
T T Qjunction case jc
--User specified jc
Substrate Temperatures
Case Temperatures
Junction Temperatures
The display tool shows component temperatures calculated from the thermal analysis.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 25http://www.calce.umd.edu
CalcePWA Thermal Analysis Module Demonstrated for Avionics Printed Wiring Board
Assembly
CalcePWA Thermal Results
Flight Equipment Board
Percentage error between the case temperature predicted by CalcePWA and the experimental data
Analysis results: Thermal analysis software in CalcePWA has been validated against experimental data.
Benefit for the EADS: Development of an optimized plan for accelerated qualification testing
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 26http://www.calce.umd.edu
Validation of calcePWA Thermal Analysis
Component type and power dissipation
calcePWA Program “PCB EXPLORER”
24 lead DIP (1.56 W) (U55) 124 134 16 lead DIP (0.32 W) (U38) 79 75
Component type and power dissipation
calcePWA Program “PCB EXPLORER”
MRCs SUPERPOSITION METHOD
24 lead DIP (1.56W) (U55)
101 110 108
16 lead DIP (0.32W) (U38)
67 62 59
Comparison of Component junction temperature ( oC) for natural convection case study
Comparison of Component junction temperature ( oC) for flow over case study
Validation of Coldplate Analysis
Validation of Conduction Analysis
CalcePWAThermal SoftwareFound to be within 5% of experimentaltest data
The thermal analysis software in calcePWA has been extensively validated against experimental test data and accepted numerical simulations.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 27http://www.calce.umd.edu
Vibration Analysis Manager
Vibration Analysis Manager allows you to assign supports to the board for consideration in the modal analysis and dynamic response. Additional options have been added to toolbar to facilitate use of the software.
SpringClamped
Simple
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 28http://www.calce.umd.edu
Analysis results include:Mode Shapes,Natural Frequencies,Board Displacement,Board Curvature,Component Displacement, andComponent Curvatures
Displaying Advanced Vibration Analysis Results
Displacement
Component Curvature
Mode Shapes
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 29http://www.calce.umd.edu
Using TC Extracted Data in calcePWA
For calcePWA, the Life Profile Manager module has been modified. Selection of an extracted temperature cycle file is done by selecting the Extacted TC Data option under the Import menu.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 30http://www.calce.umd.edu
Extracted TC Data Selection Dialog
• Input in dialog includes:– Extracted Temperature Cycles File– Maximum Temperature Offsets– Minimum Temperature Offsets
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 31http://www.calce.umd.edu
Temperature Offsets
• The temperature offsets allow the user to vary temperature of individual components from the extracted maximum and minimum temperatures by a fixed offset temperature.
The temperature offsets is defined by creating a temperature set using the Create/Import Temperature Data option under the File menu.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 32http://www.calce.umd.edu
Create/Import Temperature Data
• This program allows the user to import csv formatted data or assign data manually.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 33http://www.calce.umd.edu
Assigning Temperatures
The new option will automatically create data entry points for each component under the active design project.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 34http://www.calce.umd.edu
Highlighting Data Items
To assign component temperatures, highlight the components to be assigned and the select the Refine option under the Edit menu.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 35http://www.calce.umd.edu
Assign Temperatures
After setting package and board temperatures, selecting the Ok button will result in all highlighted components being assigned the value set in the dialog.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 36http://www.calce.umd.edu
Saving Assigned Temperature Data
After assigning the individual component temperature offsets, you can save the data set by selecting the Save or Save As option under the Filemenu.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 37http://www.calce.umd.edu
Creating the Temperature Segments
After assigning temperature offsets and the processed rainflow data, the Life Cycle Profile will automatically create the temperature load segments.
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University of MarylandCopyright © 2018 CALCE
Center of Advanced Life Cycle Engineering 38http://www.calce.umd.edu
Viewing Temperature Segments
Individual load segments can be view by highlighting the desired segment and selecting the View/Edit button at the bottom of the interface window.
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Life Assessment Results
After creating the Life Cycle Profile Database (LSPDB) from the define loading condition, you can conduct a life assessment with the calcePWA Life Assessment Manager. In this application, you will select the desired LSPCB, down select the desired fail models (if desired), and run the assessment.
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Inspecting Individual Segment Result
Failure results can be view by selecting the View button on the failure results table.
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Validation of CalcePWA Vibration Analysis
ANSYSResonant Frequencies
710 Hz1331 Hz1444 Hz
ANSYS
calcePWAResonant Frequencies
724 Hz1348 Hz1399 Hz
calcePWAModal Analysis & Displacement
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Video Processor CCA
Processor CCA
Interface CCA
1st NaturalFrequency (Hz)
CALCE
372
BFIST - XM7Vibration Analysis Results
248
303
Power Filter CCA 226
.33
13.5
.47
.66
1st Natural Frequency (Hz)
SEI ESSTest Data
Max.Displacement
(mils)CALCE
510
230
265
265
Input frequency to Solder Joint Fatigue is lowest value of CALCE
results and ESS test results
Serial I/O CCA
Backplane CCA 417
261 .61
.04410
N/A*
Validated against Measured Test ResultsVEU Video Processor CCA
Applied Boundary Conditions
Frequency and Modal Analsyis
The vibration analysis software in calcePWA has been extensivelyvalidated against experimental data and numerical simulations.
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Life Assessment
1. Select a predefined life cycle profile
2. Save life assessment problem,
3. solve life assess
Life assessment in calcePWA is conducted predefined a life cycle profiles
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Available Stress Types
Application Stress Manager
Defining the Life Cycle Profile
The Life Cycle Profile Manger allows you to define multiple loading conditions over which that PWA can be analyzed.
Stress condition refinement dialog
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PWA Life AssessmentThe life assessment module uses the PWA model, results of thermal and vibration simulations defined in a life cycle scenario to determine life expectancy of design.
Color coding to highlight items that fail to meet life expectancy
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Available Failure Models• Thermal Fatigue of Solder Interconnects
– Most conventional package styles (SOIC, PLCC, QFP, BGA, SOT, HSOP, HSLCC, PGA, DIP, LCCC, LCC)
• Thermal Fatigue of PTH• Thermal Fatigue of Die to Package Interface• Vibration Induced Fatigue of Package to Board
Interconnects– Most conventional package styles (SOIC, PLCC, QFP,
BGA, SOT, HSOP, HSLCC, PGA, DIP, LCCC, LCC)• Mechanical Shock Induced Failure of Package to Board
Interconnects– Most conventional package styles (SOIC, PLCC, QFP,
BGA, SOT, HSOP, HSLCC, PGA, DIP, LCCC, LCC)• Die Level Electromigration• Die Level Metallization Corrosion• Die Level Dielectric Breakdown
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Modeling Validation
Interconnect fatigue failure models have been validated though experimental data and detailed numerical simulation. These models are reviewed on a continual basis and updated as necessary.
1
10
100
1000
10000
1 10 100 1000 10000
Predicted Life
Expe
rimen
tal L
ife
JPL AT&T CALCE
1st Order Thermal Fatigue Leadless Chip Carrier Model Validation
BGA model has been compared against over 40 measured results obtained from the published papers, conference articles and experiments.
1st Order Thermal Fatigue PBGA Model Validation
CALCE PTH Thermal Fatigue Model
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Vibration Testing of 160 IO CABGA Test Boards
Test Dwell Input Input Resp. Resp.Freq. Acc.
(Peak-
Peak)
Acc. (g)
Acc. (Peak-Peak)
Acc. (g)
P1 209 20 10 738 369P2 210 14 7 596 298P3 206 2 1 64 32P4 209 6.3 3.15 197 98.5P5 205 10.3 5.15 303 151.5T1 205 10.3 5.15 393 196.5T2 205 6.5 3.25 198 99T3 202 6.8 3.4 280 140T4 200 8.7 4.35 347 173.5
Test boards were monitored with accelerometer and four strain gages.
Applied Loading
Mounted Test Specimen
8x4.5x0.062 inches
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Comparison of Board Strain versus Input with calcePWA Vibration Module and Test Data
Comparing test strain to measured strain shows relatively good correlation.
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Comparison of CTF
These plots contain curves for life expectancy of lead-free (SAC) and SnPb solder interconnects under harmonic load conditions at varying
input accelerations generated by the calcePWA software for the CABGA test board. Test results plotted against these curves reveal
good agreement.
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Validated Temperature Cycle Induced Solder Interconnect Fatigue Model for SAC
2 mm thick board contained PBGA, TSOP, TQFP, CLCC packages. The simulation model was based on a test vehicle used under the JGPP/JCAA Pb-free Solder Test Program. Test assemblies were subjected to a -55 to 125oC temperature cycle and a -20 to 80oC cycle condition
calcePWA Model
-55 to 125 C testExperiment
CA
LCE
Sim
ulat
ion
M. Osterman and M. Pecht, Strain Range Fatigue Life Assessment of Lead-free Solder Interconnects Subject to Temperature Cycle Loading, Soldering & surface Mount Technology, Vol. 19, No. 2, pp. 12-17, 2007.
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Model vs. Experiment Data for SN100C
1. M. Osterman, C07-06 CALCE EPSC Project, 20072. J. Arnold, N. Blattau, C. Hillman, K. Sweatman, Reliability Testing of Ni-Modified SnCu and SAC305 – Accelerated
Thermal Cycling, SMTA International 2008, pp 187-190, Aug. 20083. M. Osterman, C08-08 CALCE EPSC Project, 2008
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Material Properties Geometry Loads
Evaluate Failure Model
Time-to-FailureFFOP
TTFx
Probabilistic Physics of Failure (PPOF) Assessment in calcePWA
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Probability Physics of Failure (PPOF)• The default failure assessment process in calcePWA is to use
nominal values for all parameters with the assumption that the failure assessment results represent time to 50% failure.
• To assess the effect of input variations, you can directly vary inputs and re-run the assessment. This requires modifying model data, regenerating the LCPDB, and re-running the failure assessment.
• The PPOF capability within the calcePWA failure assessment module offers two alternatives: assigned distributions and calculated distributions. – Assigned distributions include Weibull and Lognormal which can be applied
on a model-by-model basis.– Calculated distributions are established by defining distributions to input
parameters and using a Monte Carlo technique to establish the failure distribution.
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Failure assessment is conducted in the Life Assessment Manager. Assessment is based on the selected Life Cycle Loading Scenario. Probabilistic failure assessment may be conducted by direct assignment of distributions for failure models or through Monte Carlo simulation.
Selecting PPOF Assessment for Multiple Failure Models
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n ba
a = n +lb = n+u
n ba
a = n +lb = n+u
Supported Distributions
Triangular Distribution
Where:l – Lower variationu – Upper variation
ExampleNominal Value: 5 mmUpper: 2 mmLower: -1mma = 4, b = 7
Uniform Distribution
Edit Distribution Dialog
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Handling Multiple Environments
Damage is defined as the percent of life consumed. If damage is linearly accumulated, then we define a probabilistic damage index for x percent failure as
where n is the applied time (cycles, etc) and NP(x) is the survivable time (cycles, etc). For multiple environments and the same failure site and mechanism, the total damage is the sum of the damage for the individual environments:
Failure occurs when
i
ixP
totalxP DD )()(
)()(
xPxP N
nD
1)( totalxPD
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Example of Monte Carlo Analysis
Expected life is calculated based on the defined life cycle and assumes that the loading condition persists until failure. The total damage (DR) is based on the defined life cycle loading condition.
Life Cycle Profile:1.Temperature Cycle –40 to 100oC
( 1 CPH) – 12 cycles2. Shock 20G .5s Half-Sine3. Random Vib: 0.2 G/Hz (100 to 500 Hz) – 100 hrs4. Temperature Cycle 0 to 80oC (1 CPD)
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Acceleration Factors
test
usecycle N
NAF
In product qualification, it is often impractical to test the system for its full expected lifetime. As a result, high load frequency and load levels may be used. In order to relate the test condition to the anticipated use condition, a failure assessment under both conditions must be completed. If the same failure mechanisms and sites are produced under both conditions, the test and use condition can be related. An acceleration factor is the term used to relate the test and use condition.
The ability to present acceleration factors has been recently added to the calcePWA software. In calcePWA, the acceleration factor is presented in the time domain.
test
usetime t
tAF
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Determining Acceleration Factors in calcePWA
User must create a test profile and a use profile. Both life assessments must be conducted for both profiles. To evaluate the acceleration factor for a particular use and test condition, the user should load the use condition. Next, the user should select the Run Acceleration Factor menu item and use the selection dialog to select the test assessment.
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Time Domain Acceleration Factors
The acceleration factors determined in calcePWA are presented in the time domain. As such, the time in test is related to the time under the use condition. Therefore, an acceleration factor of 50 means that a part requiring 2 months for failure under the test would required 100 months to fail under the prescribed use condition. Alternatively, if a part can survive 2 months in test, it should be expected to survive 100 months in the field.
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Assessment of Tin Whisker Risk in calcePWA
The calceWhiskerRiskCalculator has been integrated into the calcePWA . The current implementation only considers part self shorting. Later versions will
allow for evaluation of part to part shorting.
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Importing Components in calceTinWhiskerRiskCalculator
The number of pairs is calculated based on part interconnect format (SIP, DIP, QUAD)SIP : NP = Nleads -1
DIP: NP = 2*(Nleads/2 – 1)QUAD: NP = 4*(Nleads/4 – 1)
Conduct spacing gap is determined based on lead width (Wlead) and interconnect center line spacing or pitch (P)
Lgap = P – Wlead
Conductor area Aconduct = Llead*(Tlead+Wlead)
Software will report leaded components that it is unable to determine
one or more site parameters
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Risk Assessment Results from calcePWA models
After setting the target life and samples, you can evaluate the whisker risk by selecting Risk->Assessment option. This will evaluate reliability of the system defined by the set
of parts under evaluation.
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Tool Bar
Menu Bar
Model FeatureList
DataEntry Panel
CalceFAST Software Interface
CalceFAST 5.0 (Failure Assessment Software Toolkit) software provides the capability to bypass full scale design modeling and conduct failure assessment using individual failure models. The software implements a failure model plug-in interface and allows the failure model software to be used in calcePWA 5.0 andon the CALCE Web Site.
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Expanded Models in calceFAST
Package and device models from CADMP-II are now available in calceFAST.
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In the case of multiple attribute sensitivity, the attributes and their assigned values are presented in the text report. The X-axis of the graph defines the percent values over which the selected attributes were varied.
Sensitivity Analysis Results
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Iso-Time To Failure Results
DecreasingTime to Failure 1500
1250
1000
750
Cycles To Failure
1750
Iso-time to failure assessment provides you with plots that can be used to examine the effect of changes in environment loading conditions versus design parameters. From the example above, a reduction in plating thickness by 0.01mm can reduce the life by 44%.
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calceFAST Implementation
The calceFAST implementation assumes the user has already processed a time history file and “Import Extracted Temperature Cycle Data” option allows the user to select a processed output file.
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Segmented Temperature Cycles
In order to view the segmented temperature cycles, you will need to select the Multiple Stress Condition Options.
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Segmented Temperature Cycles
In order to conduct an assessment with the segmented temperature data, you will need to assign the Analysis Mode to Multiple under the Analysis Parameters Feature Panel.
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calceFAST Fatigue Model Output Example
After saving and executing the analysis, the results are presented with damage ratios for each segment.
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calceEP Device and Package Level
Package and Device Life AssessmentLife Cycle Profiling
Package and Device ModelingToolbox
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calceEP Failure Models
• Electromigration• Stress Driven Diffusive Voiding (SDDV)• Time Dependent Dielectric Breakdown (TDDB)• Metallization Corrosion• Electrolytic Breakdown • Dielectric Breakdown• Die Attach Thermal Fatigue• Wire Bond Thermal Fatigue
Failure models are based on those available in open literature and JEP122. As well as those internally developed at CALCE. List of supported failure models will include:
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Whisker Risk Assessment Software
A software package that implements the fixed risk assessment algorithm has been developed. Software allows you to define conductor pairs and select finish type to look up whisker growth or directly define whisker growth parameters.
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Conducting A Risk Assessment
The software allows you to define the target life time of the system, desired risk level in parts per million, and the percentage of whisker containment afford by the application of a conformal coat. The target life is used in combination with the database of whisker growth tables to determine the whisker growth characteristics. The risk level is used to define the sample size (i.e. the number of Monte Carlo iteration).
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Risk Assessment Results
The software outputs the probability of whisker failure for each conductor pair considered. The probability of failure for each conductor pair is then rolled up to provide the total whisker reliability of the system.