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Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
What is CALCE?Center for Advanced LifeCycle Engineering(founded 1987) is dedicatedto providing a knowledgeand resource base tosupport the developmentand sustainment ofcompetitive electroniccomponents, products andsystems.
Areas of research
• Physics of Failure• Design of Reliability• Accelerated Qualification• Supply-chain Management• Obsolescence• Prognostics
~24 Faculty and Research Staff~20+ M.S. students~60+ Ph.D. students
CALCECALCEElectronic Productsand Systems Center
~$5M/Year
CALCECenter for Advanced
Life Cycle EngineeringRisk Mgmt in
Avionics Systems
• Manufacturing for sustainment(USAF ManTech Program)
• IEC and avionics workinggroup collaboration
LabServices
• Small jobs• Fee-for-service• Proprietary work• Use of CALCE Tools &
• Larger programs• Some past programs:• Power Electronics (Navy)• Embedded Passives (NIST)• Risk Management (USAF)• Life Assessment (NASA)• MEMS (NASA,NSWC)
• Risk assessment, mitigationand management of electronicproducts and systems
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
CALCE EP&S Consortium Research ProgramCALCE EP&S Consortium Research Program
Research Program Theme(Identification and development oftechnologies, methodologies, andguidelines for assessing, mitigating, andmanaging the risks associated with thedesign, manufacture and fielding ofelectronic products and systems)
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
Test Results for Tmean = 50oC, T=100oC
x 10x
1.00
5.00
10.00
50.00
90.00
99.00
Probability - Weibull
Time, (t)
Unre
liabili
ty,F
(t)
8/24/2004 09:43CALCE Center
WeibullLccc68 Sn/Ag
W2 RRX - SRM MEDF=16 / S=0Lccc68 Sn/Ag/Cu
W2 RRX - SRM MEDF=16 / S=0Lccc68 Sn/Pb
W2 RRX - SRM MEDF=15 / S=0Lccc84 Sn/Ag
W2 RRX - SRM MEDF=15 / S=0Lccc84 Sn/Ag/Cu
W2 RRX - SRM MEDF=16 / S=0Lccc84 Sn/Pb
W2 RRX - SRM MEDF=16 / S=0
At lower cyclicmean and maxtemperatures thePb-free soldersoutperformed SnPbsolder. This may berelated to the lowercreep rate of thePb-free soldersunder test ascompared to theSnPb solder.
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
Comparison of Time to Failure(68 IO Package)
For the Pb-free solders, increasing the average cyclic temperature showed adecrease in time to failure. As can be seen in the above chart, the behavior of theSnPb solder at the 100 and 125oC peak temperature shows non-monotonicallydecreasing behavior.
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
CALCE Strain Range Based Solder FatigueRapid Assessment Model
For eutectic solder,
• f Constant
•
1
1
2 2
cp
f
f
N
• Nf : mean number of cycles to failure
• p : inelastic strain range, g (package type,geometry, dimension, material property, load profile)
• K lead stiffness
• f model calibraton factor
• f = material constant, fatigue ductility coefficient
• c = material constant, fatigue ductility exponent, h(load profile)
• Tsj: mean cyclic temp. (°C)
• tD: dwell in minutes at the max. temp.
This model is preferred since it provides a physical relationship between thetemperature cycle load and failure and it has a quick solution time.
h
p
Ld
Ld (T) /2
Engelmaier, W., "Fatigue Life of Leadless Chip Carrier Solder Joints During Power Cycling,", Components,Hybrids, and Manufacturing Technology, IEEE Transactions on, Volume: 6 Issue: 3 , Sep 1983, pp. 232 -237
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
Fitted Strain Range Model Parameters
2.253.472.25f*[1]
0.8980.9660.980R^2
1.40E-027.83E-031.45E-02c2
-2.10E-03-1.74E-03-7.34E-04c1
-0.416-0.347-0.502co
SASACSnPbSolder
Parameters
[1] The fatigue ductility constant was derived onlyconsidering the neutral distance length of thepackage. This value must be adjusted withrespect to the cyclic temperature range, CTEmismatch between the package and the board, andthe effective solder joint height.
d
sjt
cTccc360
1ln210
f = Constant
c
f
fe
TLN
1
]1[22
1
Norm
aliz
edF
atig
ue
Lif
eA Strain Range Based Model for Life Assessmentof Pb-free SAC Solder Interconnects , M. Osterman,A. Dasgupta, B. Han, 56th Electronic Component andTechnology Conference, pp. 884 - 890, May 30-June2, 2006 Dwell Time (hrs)
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
2 mm thick board contained PBGA,TSOP, TQFP, CLCC packages. Thesimulation model is based on testingconducted 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
•JCAA/JG-PP No-Lead Solder Project:-55ºC to +125ºC Thermal Cycle Testing Final Report, David Hillman and Ross Wilcoxon, March 15, 2006
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
Comparison of Simulation Results
Experiment Results
Sim
ula
tion
Results
TSOP (-20 to 80oC)
TQFP (-20 to 80oC)
Parts include (BGA,CLCC, TSOP, TQFP).Current model overestimates life of leadedparts. This result islikely due to the squareof T in estimating thestrain range for leadedparts.
•Data was obtained from
•JCAA/JG-PP No-Lead Solder Project:-55ºC to +125ºC Thermal Cycle Testing Final Report, David Hillman and Ross Wilcoxon, March 15, 2006
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
Time To Failure Results Under Random VibrationAssembly comparison after 125C/100hrs aging
100
120
140
160
180
200
220
240
260
280
400 600 800 1000 1200 1400 1600 1800 2000
Strain (μe)
Tim
e-t
o-f
ailu
re
SnPb
OSP
Assembly comparison after 125C/350hrs aging
100
120
140
160
180
200
220
240
260
280
400 600 800 1000 1200 1400 1600 1800 2000
Strain (μe)
Tim
e-t
o-f
ailu
re
SnPb
OSP
At low strain levels,below approximately 700e SAC out lasts SnPb.The slow of SAC isshallower than SnPb.Both SAC and SnPbshow a degradation dueto thermal aging. Earlierfailures were ball gridarray parts.
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
http://www.calce.umd.edu/lead-free/tin-whiskers
CALCE Tin Whisker Study
In addition to conducting multiple research projects on lead free solder issues this past year, CALCEjoined with a number of companies to author an alert regarding the use of pure tin as a surface finish.
This alert was followed closely by a mitigation guide authored by CALCE with inputs fromcompanies participating in the Tin Whisker Alert Working Group.
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
BGA(SnAgCu)
(Sn)
(Sn) (Sn)
(SnCu) (SnCu)
(SnCu)
(SnBi)
(SnBi) (SnBi)
QFP
FR4 board
CALCE Long-term Reliability of Mixed SolderStudy
Objectives:To provide participants with a critical assessment of the reliability of solderjoints formed with lead-free parts and Pb-based solder. This is particularly aconcern for companies that are attempting to maintain Pb-based solder.
Temperature Cycle Test Board
• Evaluations
– Intermetallics characterization underisothermal aging at 125ºC for 100,350 and 1000 hours
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
Long-term Reliability of Pb-free ElectronicAssemblies in Contaminating Environments Study
Objective: To assess the long-term reliabilityof lead-free electronic assemblies subject tocontaminating and corroding environments.
CALCE Team: Sheng Zhan, Michael H. Azarian,Michael Osterman and Michael Pecht
Approach: Select board material and metalfinishes will be evaluated undertemperature/humidity/bias conditions withtest cells exposed to defined contaminationexposures as per Telecodia and surfaceinsulation resistance (SIR) will bemonitored.
Expected Benefits: Documented corrosionresistance measurements for a range of Pb-free materials and impact of contamination ofcorrosion based time to failure.
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
FY07 CALCE Pb-Free ResearchC07-07 Solder Joint Reliability of Reworked/Repaired SMT AssembliesC07-01 Reliability of Pb-free and Reballed PBGAs in SnPb Assembly
ProcessC07-04 Solder Joint Reliability of Solder Dipped (SAC/SnPb) Leaded SMT
Packages in a SnPb Assembly ProcessC07-03 Effect of Long Dwell on Thermal Cycling Fatigue Damage for Pb-
Free Solders (Continuation of C06-03)C07-06 Effect of Temperature Cycle on the Durability Pb-free Interconnects
(Sn96.5Ag3.0Cu0.5 and SnCuNi) (continuation C06-06)C07-48 Characterization and Reliability Assessment of Lead-Free Solder
Alloys in High Temperature ApplicationsC07-02 Accelerated Qualification of SAC Assembly: Combined
Temperature Cycling & Vibration (Continuation of C06-02)C07-05 Tin Whisker Growth and Risk Assessment UpdateC07-08 Characterization of Tin Pest Formation in Pb-free Solder JointsC07-27 Characterization of PCB Laminate Materials Properties after Lead-
free Reflow CyclesC07-47 Acceleration factors in electrochemical migration
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
FY07 CALCE EPSC ResearchFailure MechanismsC07-10 Effect of solder fillet and composition factors on MLCC crackingC07-11 Reliability of Large Electrolytic CapacitorsC07-14 Electronic Component Failure Categorization under High G LoadingC07-34 Area Array Components Warpage Sensitivity
New Technologies and ProcessesC07-09 Hygroscopic Characterization of Polymer Materials beyond Glass
Transition TemperatureC07-12 Failure Mechanism & Reliability Assessment for System-in-Package
Technologies (Continuation of C06-12)C07-16 Detection of interconnect degradation using impedance analysisC07-17 Accelerated Testing of Flex AssembliesC07-18 Fundamental Understanding MEMs Structures Subjected to High Shock
LoadsC07-20 Qualification of a Stamped Metal Contact SocketC07-22 Measurement of Effective Chemical Shrinkage of Polymeric MaterialsC07-30 Characterization of Moisture-induced Degradation of Polymer InterfaceC07-31 Solder Assessment for SiC Device AttachmentC07-45 Power Cycling Durability of Advanced Power Modules
Center for Advanced Life Cycle Engineeringhttp://www.calce.umd.edu
FY07 CALCE EPSC Research
Part Management and SustainmentC07-23 Life Cycle Supply Chain Data Mining and InterpretationC07-24 Implementation Cost of Lead-Free and Tin Whisker Mitigation
Performance StandardsC07-25 Life Cycle Cost of Component Management: Understanding the
Component Reuse Business CaseC07-32 PoF Guidelines for Qualifying FPGAsC07-41 Counterfeit Electronic PartsThermal ManagementC07-26 Enhanced Conventional Thermal Solutions for LED PackagesC07-29 Thermal Performance and Reliability of Thermal Interface MaterialsVirtual QualificationC07-15 Shock –calcePWA Shock Model Improvements (continuation of C05-15)C07-21 Modeling Mechanical Torsion of PWA in calcePWAC07-28 Probabilistic PoF Modeling: Effect of Number of I/O on Thermal Cycling
Durability PredictionsC07-46 Model-based Design Guidelines for Shock & Drop Loading (Continuation