Mechanical Reliability of Electronics
Tim PawlakR&D Fellow
1? 2016 ANSYS, Inc.July 26, 2017ANSYS Confidential
PCB Assembly Reliability Analysis
?PCB Assembly Failure Modes
?Challenges of modeling PCB Assemblies?ANSYS Mechanical Workflow?Trace Mapping
?Thermal Analysis –Joule Heating Hot Spot Detection?Solder Reflow –Board-Level Warpage Analysis?Vibration –Modal and Random Vibration Analyses?Automated Post-Processing
?Thermal Cycling -Solder Joint Fatigue
?Conclusion
2? 2016 ANSYS, Inc.July 26, 2017ANSYS Confidential
PCB Assembly Failures Modes
?Mechanical failure of PCB assemblies are primarily due to thermal and vibration issues.
ThermalVibrationHumidityDust
Electronics failure modes
US Air force Avionics Integrity Program
?As packages become thinner and boards become thicker, the risk of failure increases and becomes harder to predict using traditional design rules.
?ANSYS provides a full set of tools to model the entire PCB assembly efficiently. This
allows engineers to foresee issues during the design process.
3? 2016 ANSYS, Inc.July 26, 2017ANSYS Confidential
Challenges of Modeling PCB Assemblies
?Geometry complexity?PCB
?Electronics Components
?Complex material models for solder
PCB
?11 layers
?21,000 bodies
(including trace and via)
Anand’sViscoplasticitymodelR. Darveaux, “Effect of Simulation
Methodology on Solder Joint Crack Growth Correlation”, ECTC 2000
4
? 2016 ANSYS, Inc.
July 26, 2017
Electronics components?585 bodies
?324 solder bodies on one chip
Board design from:
https://kosagi.com/w/index.php?title=Kovan_Main_Pageopen hardware robotics platform
ANSYS Confidential
ANSYS Mechanical Workflow
Submodelof chip with solder balls
PCB assembly CAD
?PCB sliced so that each
layer is a separate body (for trace mapping)
Solder reflow warpage simulation
?With submodelingof crucial componentsOperating condition
thermal stress simulation with joule heating
Model and random vibration analysis
ODB++ layout file for trace mapping
5
? 2016 ANSYS, Inc.
July 26, 2017
Joule heating results from DCIR Simulation
ANSYS Confidential
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