While HFSS and SIwave are well known for electromagnetic and signal integrity simulations, AEDT also provides a Mechanical solver that allows engineers to study stress, strain, deformation, and thermal effects in electronic structures. This is especially important for advanced packaging, solder joints, and PCB assemblies, where mechanical reliability is as critical as electrical performance.
In this article, we review the basic principles of stress and strain, the setup of a mechanical simulation in AEDT, and how to use parametric sweeps to evaluate warpage and stress distribution across temperature ranges.
Fundamental Concepts
Stress and Strain
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Stress (σ): Defined as force per unit area.
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Strain (ε): Defined as the relative change in length, ΔL/L.
In the elastic region, stress and strain are related by Hooke’s Law:
where E is the Young’s modulus.
Shear Stress and Shear Strain
Shear stress (τ) and shear strain (γ) follow a similar linear relationship:
where G is the shear modulus.
Stress–Strain Curve
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In the elastic region, the material returns to its original shape when the load is removed.
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Beyond the yield point, the material enters the plastic region, where permanent deformation occurs.
Ref1.
Excitations in Mechanical Analysis
Unlike HFSS, Mechanics does not require an air region around the model. Instead, you apply boundary conditions and excitations directly to the structure. Common excitations include:
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Pressure
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Force
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Displacement
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Thermal load
In many electronic applications, thermal load is the most important, as temperature cycling drives mechanical stress and long-term reliability concerns.
Boundary Conditions
AEDT provides several boundary condition types for mechanical constraints:
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Fixed support: No displacement in any direction.
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Frictionless support: Movement is restricted normal to the surface, but tangential sliding is allowed.
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Cylindrical support: Radial and tangential constraints applied to cylindrical surfaces.
The choice of boundary conditions has a strong impact on the predicted stress and deformation, and should reflect the actual physical mounting of the PCB or package.
Example: PCB with Die and Solder Pillars
Consider a simple package assembly:
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A PCB substrate,
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A die mounted on top,
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Solder pillars connecting the die to the board.
In a mechanical simulation, you assign appropriate materials (e.g., FR4, silicon, SAC solder) and define the initial geometry. Thermal load is applied by sweeping the temperature from 20 °C to 120 °C.
Simulation Workflow
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Geometry creation: Import or build the PCB, die, and solder geometry.
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Material assignment: Assign proper elastic and thermal properties to each body.
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Excitations: Apply a thermal sweep (20 °C → 120 °C).
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Boundary conditions: Apply fixed or frictionless supports at board edges or mounting points.
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Solver setup: Define a mechanical solver in the analysis tree.
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Parametric sweep: Use Optimetrics to sweep temperature and capture deformation/stress at each step.
Now the model is ready to be solved
Results
The outputs of an AEDT mechanical analysis include:
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Stress distribution plots: Show where maximum stresses occur in solder joints or die corners.
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Strain maps: Indicate relative deformation. Select all objects, then plot the displacement
Then right-click the parametric sweep, and select show results
Select 20cel and apply
Select 40cel and apply
60, 80, 100, then 120
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Warpage vs. temperature curves: Help assess risk of board/package bending.
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Effect of supports: Changing constraints (fixed vs frictionless) shows how mounting conditions alter stress and warpage. Reduce the number of Frictionless restrictions to 2, 1, then 0 (none) at 120cel:
Conclusion
AEDT Mechanics extends the simulation environment beyond electromagnetic effects to include thermal and mechanical reliability analysis. With the same familiar interface, engineers can:
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Apply loads (thermal, force, displacement, pressure),
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Use realistic boundary conditions,
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Run parametric sweeps over temperature,
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Visualize stress, strain, and warpage.
This makes AEDT a powerful single environment for evaluating not only electrical performance but also mechanical robustness of modern electronic assemblies.
Ozen Engineering Expertise
Ozen Engineering Inc. leverages its extensive consulting expertise in CFD, FEA, optics, photonics, and electromagnetic simulations to achieve exceptional results across various engineering projects, addressing complex challenges such as antenna design, signal integrity, electromagnetic interference (EMI), and electric motor analysis using Ansys software.
We offer support, mentoring, and consulting services to enhance the performance and reliability of your electronics systems. Trust our proven track record to accelerate projects, optimize performance, and deliver high-quality, cost-effective results. For more information, please visit https://ozeninc.com.
If you want to learn more about our consulting services, please visit: https://www.ozeninc.com/consulting/
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