30 May, 2019
Last month, I gave a talk at Cadence’s CDNLive event on the changing nature of electronics and the need for thermal engineers to start considering combined electrical and thermal simulations within their designs.
Why do we need electro-thermal co-simulation?
As devices increase in complexity, detail, size and scope, more and more engineers are turning towards electro-thermal co-simulation as a means to solve challenging design problems and ensure product reliability. Today, many engineers are running electrical and thermal simulation in tandem. It allows them to predict, with a greater degree of accuracy, the heat and temperature distribution in complex circuit boards. With electro-thermal co-simulation, engineers identify which components will be exposed to excessive heat or inadequate cooling; taking them outside their design envelope and impacting the mean time between failures (MTBF) for the product as a whole.
Given the demands placed upon modern electronics devices, electrical function is now so closely coupled with power distribution that conducting electrical simulation in isolation is no longer feasible. For example, a generally energy efficient circuit can see internal temperatures soar due to spikes in current demand. This often occurs at local bottlenecks in the circuitry, and the device then runs the risk of overheating. While it’s possible to identify this problem by conducting a simulation of the board-level current flow, thermal analysis is needed to identify thermal bottlenecks to ensure proper dissipation of heat and protect the components from exceeding the recommended levels.
Being able to extract the appropriate boundary conditions from the CFD simulation, which then are imposed on the electrical simulation tool, presents another major push for electro-thermal co-simulation. The boundary condition is the surface heat transfer that is applied onto the electrical components. With CFD simulation, you can accurately model the impact that the external system and the environmental conditionals have on the thermal performance of components, which in turn has an impact on the electrical performance of the components.
Due to various elements within the chip not being isolated and easily confined, it’s vital for engineers to consider the connection between (and interaction with) surrounding environments such as the package, PCB characteristics and the enclosure from a heat transfer perspective. The external environment has a massive impact on the thermal performance of the system, which in turn has an impact on the electrical performance of the system.
As functionality increases in smaller form factors, electro-thermal co-simulation is a must for many designs. Despite this growing need, many electrical and thermal teams still use disconnected software toolsets that cannot easily integrate, and for the combination’s that do exist, they compromise on key modeling features, such as meshing and CAD import.
What does the co-simulation process look like?
That’s where 6SigmaET, the leading thermal simulation tool for electronics design, and Cadence, the leading electronics design automation software provider, come in. Using these tools in tandem enables engineers to do more in the same amount of time with:
The process of co-simulation between Sigrity PowerDC and 6SigmaET follows five easy steps:
Step 1: From Sigrity PowerDC, an initial board design can be exported either as an MCAD or ECAD. This design also includes defining the resolution for the heat transfer coefficient (HTC) map on the board and components.
Step 2: This board design can be easily imported into 6SigmaET with the preferred level of detail – this level of detail ranges from a simplified uniform conductivity board to a fully detailed import of all layers.
Step 3: In 6SigmaET, engineers can run multiple design iterations and transient simulations using CFD to achieve the desired temperature conditions. An HTC map is generated on the board and components.
Step 4: The final HTC map is then exported out of 6SigmaET and imported into Sigrity PowerDC for accurate representation of convective heat transfer.
Step 5: An FEA solution provides final detailed simulation results with accurate boundary conditions.
With 6SigmaET, coupled electro-thermal co-simulation is now a reality. By solving their designs in our software suite, engineers can benefit from unified file transfers that are automated and seamless. This process enables efficient and effective collaboration, speeding up the design process by reducing time and errors, while also enabling engineers to make multiple alterations to their designs.
Blog written by: Priam Fernandes, Sales Manager
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