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© 2004 – 2010 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Best Practices in Accelerating FEA
in Abaqus, Ansys®,
and NX Nastran
Dr. Gil Sharon
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com2
Speaker Bio: Gil Sharon
o Senior Application Engineer. email: [email protected]
o Research focus:
o Mechanical reliability of electronic systems and components
o Multidisciplinary reliability of complex electro mechanical systems
o Characterization and modeling of material behavior
o Physics of failure of electromechanical and MEMS system
o Mechanical performance of flip chip packages
o Doctoral research
o Solder reliability
o MEMS structures characterization
o Embedded components failure analysis
o Particle beam accelerator mechanical fatigue.
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com3
Agenda
o Overview
o Board and BGA model creation
o Inserting a board to an enclosure
o Abaqus/ANSYS WB
o Adding a stiffener
o ANSYS classic
o Nastran as the solver
o New feature
o Creating a model for BGA packages
o Via modeling
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com4
Overview
o Finite element analysis of can be used to simulate several issues in board design
o Vibrationo Random vibration
o Harmonic vibration
o Modal Frequency analysis
o Board bendingo In circuit test (Static structural)
o Mechanical shock (Transient dynamic)
o Thermo-mechanical induced issueso Solder fatigue analysis
o Stresses in vias during reflow
o Warpage
o This webinar concentrates on how Sherlock can accelerate the analysis capabilities of FEA solvers.
o Faster model creation
o Automated processing of FEA results to reliability predictionso In some cases
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com5
Board and BGA Model Creation
o A PCB model consists of:
o Components
o Leads/BGA solder balls
o Component body
o Board
o Copper
o Resin
o Laminate
o Stiffeners/mounts
o Enclosure or chassis is not part of the board
o BGA models consist of:
o Solder Balls
o Custom Patterns
o Laminate
o Die
o Overmold/ Bare die
o Passives
o Laminate models
o Uniform properties
o Layer by layer
o Mosaic
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com6
PCB Model in Sherlock
o Import the board from eCAD files
o Verify the component placement
o Location
o Rotation
o Enter the component properties
o Verify the board properties
o Export the board to FEA
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com7
Open a Design File Directly From ODB++ “File.tgz”
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com8
Design Capture - Graphic Verification
o Files Viewable As PCB Layerso Provides Feedback To The User
o Users can modify, delete and add parts
o Users can modify mount pointso Boards can be stacked up and
assembled together
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com9
Verify Component Placement
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com10
Verify the Part Properties
o Enter the component properties
o Loaded from part library
o Entered by hand
o Sherlock will calculate the reliability of components even if they are not exported to the FEA
o Based on component location
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com11
Verify the Board Properties
o From the material properties of each layer Sherlock calculates:
o Thickness
o Density
o CTE x-y
o CTE z
o Modulus x-y
o Modulus z
o Using the built-in laminate data library
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com12
Exporting the Board from Sherlock
o Right click and select
“Export FEA Model”
o Select
option
o Geometry
o Selected components on the board
o Creates mount point, heat sink, wire bond etc.
o PCB geometry including drill holes and cutouts
o Assembly of all the parts in the correct location
o Tied contacts for everything
o Merged mesh option
o Materials
o Materials for each material defined in Sherlock
o Material for the board
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com13
Inserting a Board to an Enclosure (ANSYS WB)
o Export the model as a step file and import it to ANSYS
workbench
o Import the chassis file
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com14
Inserting a Board to an Enclosure (ANSYS WB)
o Use the Sherlock plugin to read the materials for each
part and the board
o Apply the material of the case
o Mesh the model
o Run the analysis
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com15
Inserting a Board to an Enclosure (ABAQUS)
o Export the model as an ABAQUS file and import it
o Import the enclosure, mesh and run
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com16
Inserting a Board to an Enclosure (ABAQUS)
o Results in ABAQUS:
o After the analysis is completed we
can import the results to Sherlock for
reliability predictions
Board Inside Case
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com17
Inserting a Board to an Enclosure (ABAQUS)
o Imported results in Sherlock:
o After the analysis is completed Sherlock can export the results with the usual report
Board In Abaqus Board In Sherlock
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com18
Adding a Stiffener (ANSYS Classic)
o Export model as ANSYS APDL
o Read input from…
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com19
Adding a Stiffener (ANSYS Classic)
o Model the additional bracket
o Apply the loads
o Run the analysis
o Import the results to Sherlock to produce a reliability prediction
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com20
NX Nastran and Sherlock
o New feature
o Sherlock can now use NX Nastran as an FEA solver
o Natural frequencies
o ICT
o Random vibration
o Harmonic vibration
o Mechanical Shock
o Sherlock can also export native NX Nastran files (*.bdf) that can be opened and modified in the GUI
o Results from NX Nastran can be imported for analysis in Sherlock
o The *.pch result files are supported
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com21
Creating a Model for BGA Packages
o Example: overmold BGA with passives
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
o Sherlock can export a detailed mesh for all the layers of
the BGA
22
Creating a Model for BGA Packages
BGA LayoutBottom Layer
Detailed Mesh
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com23
Creating a Model for BGA Packages
o Option for using the Sherlock calculated material properties for each layer
o Sherlock can also export the Laminate/PCB as a uniform material
o If you have material properties from test
o Simplification
PCB TopPCB Layout
BGA Bottom
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com24
Creating a Model for BGA Packages
o Example: PoP BGA
o Each package has a die, substrate and BGA balls
o The PoP BGA is overmolded
PoP DiePoP Overmold PoP Substrate PoP Solder
BGA Die
PCB
BGA Substrate BGA Solder
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com25
Creating a Model for BGA Packages
o PoP BGA created in Sherlock
Detailed Ball
Sherlock Created Ball
o Sherlock will create all the BGA balls with a simplified geometry
o It is up to the user to mesh the model in the FEA tool
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com26
Creating a Model for BGA Packages
o Let’s take a closer look at a simpler PoP Package
PoP BGA
PoP BGA
Main BGA
PoP BGA Assembly in AbaqusPoP BGA Assembly in Ansys
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com27
PoP BGA Example
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com28
Via modeling
o Up until recently it was prohibitively expensive to model plated microvias
o Model creation time
o Solvers
o Current solvers have the power necessary to compute results for thermo-mechanical issues
o Via modeling is performed in Sherlock and exported to Abaqus or Ansys
Flange
Buried Via Through Via
Stacked Via
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com29
Via modeling – Scaling the Problem
o Mesh portions of the PCB
o Appropriate for many layers
o Mesh a complete board
o Low layer count
o A 10X10 [mm] area with a 50X50 [µm] mesh size
o Each layer will have 40,000 elements
o 8 layers will have 600,000 elements!!
Stacked Via
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Via Modeling - Model Methodology
o Automate the extraction of accurate three-dimensional conductor geometry from traditional electronic CAD-to-CAM files formats
o Gerber, ODB, IPC 2581, GDS II and MCM
o Interfaces between materials
o Identification of either vector data or image representation.
o Circular features in positive (copper) and negative (laminate) space are configured for mesh creation through defeaturing and computation of arc length segments.
Sherlock Traces Original Layout
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Via Modeling – Closer Look
o Curved traces and other features are translated into poly-lines using an advanced edge-detection algorithm developed by DfR Solutions
o Segment-generating algorithm
o Users select four variables for Sherlock to smooth out small features
Finer Features
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Via Modeling – Abaqus Model import
o Sherlock creates a Python script for ABAQUS
o The geometry is organized in selectable geometry sets
Finer Features
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com33
Via Modeling – ANSYS Classic
o Sherlock creates an APDL script for Ansys
o The geometry is organized in selectable components
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com34
Extra: Combine Sherlock FEA Features
Lead modeling
Trace modeling
PCB cutout
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com35
Summary (If you remember nothing else…)
o Shorten model creation times for Abaqus, Ansys
Workbench, Ansys Classic and Nastran.
o Leverage Sherlock’s libraries and easy interface to
automate your analysis
o Import FEA results to Sherlock and produce a reliability
prediction
o Computing power is increasing and with it the model
complexity.
o Solving ~2M elements is not a problem
o Engineer time is more valuable than computer time
9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com36
Questions?
o Presenter email: [email protected]
o Sales contact: [email protected]
