Below are the questions asked during the event, along with their respective answers.
Q: For the early phase of IC design, there are usually no detailed package or board designs readily available. How would this tool handle that kind of situation for thermal analysis?
A: This tool can generate simplified thermal models for package and board, while it cannot create them out of nothing. Users may provide generic information about the geometric profiles and material properties of the package and or board, so the tool can come up with simplified but reasonable thermal models for further analysis.
Q: You mentioned this thermal tool includes thermal stress and warpage simulation. How about other multi-physics interaction of thermal effect with, for example, electromagnetic interference, mechanical stress, or vibration?
A: At this moment this tool includes thermal, fluid flow, and linear thermal stress analyses. We are definitely moving toward multi-physics simulation, and other types of simulation such as mechanical stress and vibration are on our current roadmap. Electromagnetic interference (EMI) will be another focus we are actively working on.
Q: How long does it take to prepare the model for the result (pre-processing, meshing & solving time)?
A: The time spent on obtaining simulation results mainly depends on the physical size and complexity of the model. We have been constantly solving 3D models up to more than 100 million elements. We employ many advanced techniques to enhance the computational performance. One of the key features is the massive parallel execution of the solver, which can achieve almost linear scalability in runtime enhancement and memory reduction of computation.
Q: How are bond wires thermally modeled? Are you using 1D connectors? Is peripheral heat loss from wire taken into consideration?
A: The bond wires can be simulation in true 3D configurations. The tool can read in the package design file, for example, in the SiP format which contains information on bond wires. Additionally, the package mold is also included in true 3D shape. This way the heat transfer through bond wires can be accurately simulated in the design details.
Comment: I really didn’t see the co-simulation illustrated.
Response: Within the time constraint of the webinar, the electrical-thermal co-simulation was demonstrated by the “results”. Once the electrical effects are included (having the Joule heating as additional heat sources), the maximum temperature within the system is shown to be significantly higher than the maximum temperature without the Joule heating. The electrical simulation and thermal simulation are performed through iteration to reach equilibrium. If desired, we are more than happy to give a more complete demo of this key feature of the tool.
Q: Is there feedback between temperature-dependent electrical properties and the thermal results? Can feedback loops be accurately modeled?
A: Yes, the modification of electrical properties due to temperature is calculated in the iterative process of electrical-thermal co-simulation, since the changing of temperature will further affect the electrical properties. The co-simulation will keep going until reaching equilibrium.
Q: Is the CFD coupling done directly and iteratively? Or does the user have to map HTC’s?
A: CFD simulation can be directly coupled with the solid parts for steady-state thermal-fluid simulation, while in that scenario the solid parts usually cannot be resolved in the design details. In this tool, we can extract HTCs from CFD results as mentioned above, and then map them to solid surfaces for details finite-element analysis of the solids. For transient thermal-fluid simulation, at this stage, FEA and CFD simulations are coupled but not done iteratively. In most applications of electronic systems, the heat dissipation through fluid flow to environment would be less sensitive to the quick power changing within the chips or packages. To our experience even when the effect is moderately sensitive, usually it’ll take a few iterations to obtain satisfactory results. Of course, we can implement enhancement of automatic iterative calculation between FEA and CFD for transient analysis if needed.