Top 5 PCB thermal design tips for faster time-to-market
Thermal design mistakes can be costly, leading to frustrating PCB re-spins and delayed product launches. Thermal teams are under constant pressure to move fast without sacrificing model credibility. This blog post offers a practical “cheat sheet” for thermal engineers working against aggressive schedules, highlighting five actionable tips to prevent common thermal design pitfalls and accelerate your time-to-market. For a deeper, step-by-step look at predicting component temperatures in real designs, you can download our white paper, 10 Tips for Predicting Component Temperatures.
We still see teams defer thermal analysis until validation, only to discover component temperature violations that force weeks of rework. If this sounds familiar, you’re not alone and it’s absolutely preventable. By making the right modeling decisions at the right stage of the design flow, you can avoid these setbacks.
1. Model the right components (Not all of them)
It’s impractical and, frankly, unnecessary to model every single component on a PCB in detail. Focus your efforts where they matter most. Thermally benign components with low power density and minimal thermal sensitivity can be treated as background heat sources. This saves valuable time in early design phases. Reserve detailed thermal models for high-power, thermally sensitive components whose thermal management significantly impacts the overall product design. Simcenter provides filtering options to automate this in later design stages when importing populated board layouts.
Create detailed packages to create compact thermal models
2. Use realistic power estimates, not worst-case maximums
Overestimating power consumption by using maximum-rated power can lead to over-engineered and expensive cooling solutions, consuming unnecessary board real estate. While maximum rated power might be the only available data in early design, it’s crucial to refine these estimates as the design evolves. Power budgets for individual components and the entire board can change, so regular re-evaluation is essential. Electrothermal simulation tools, such as Siemens EDA’s Xpedition AMS, can extend electronic circuit simulation to include advanced performance simulations and virtual in-system verification, helping you achieve more accurate power estimates.
3. Match thermal model fidelity to the design stage
The choice of component thermal model should evolve with your design. In early stages, when board routing and layer counts are still undefined, highly sophisticated models are not necessary. As the PCB model becomes more refined, so too should the component thermal model. This iterative approach allows you to focus on critical components that “self-indicate” the need for more detailed analysis and potential component-specific thermal management solutions, such as thermal vias. Over-engineering models in early design phases wastes time and resources.
4. Validate early with compact thermal models
Don’t wait for late-stage surprises. DELPHI compact thermal models offer an excellent balance of accuracy and speed, typically predicting junction temperatures within +10%. These models are suitable for most detailed design work and can help you validate your thermal design choices early in the process. Simcenter Flotherm PACK and Simcenter Package Creator, for instance, provide wizard-based tools to create 2-Resistor, DELPHI and detailed thermal models based on common input data, allowing for efficient model creation and refinement.
Virtual JEDEC test environment for creation of 2R and DELPHI models
5. Don’t leave heatsink design to the end
Heatsink design is not an afterthought; it’s a critical aspect that must inform board layout, not follow it. A late heatsink design almost invariably triggers a costly re-spin. Because the major heat flow path out of a component often goes into the heatsink, designing a custom heatsink can and should begin before board routing. This ensures that the necessary board real estate for heatsink attachment is reserved, preventing significant delays and redesigns.
Optimize your PCB’s thermal design
By implementing these five tips, thermal engineers can make earlier, better-informed thermal decisions and avoid late-stage design iterations, ultimately accelerating product development and reducing costly design iterations.
Learn how to put these PCB thermal design tips into practice with Simcenter Flotherm and support earlier, more informed thermal decisions in your design process.
FAQ’s – What others are asking about PCB thermal analysis
Q: What is the most common cause of inaccurate component temperature predictions? A: Using worst-case maximum power ratings instead of real operating power estimates and selecting thermal models that are too simplified for the design stage are common culprits.
Q: Do I need a detailed thermal model for every component on my board? A: No. In most designs, low-power, thermally benign components can be captured as background heat loads. Reserve detailed models for high-power or thermally sensitive components.
Q: When should I start heatsink design in my PCB layout process? A: Before routing begins. The heatsink footprint directly affects board real estate. Designing it late almost always forces a redesign iteration.
Q: What is a DELPHI compact thermal model and when should I use it? A: A DELPHI model uses a network of thermal resistors with partitioned surfaces to accurately predict junction temperatures (typically within +10%) without the solve time of a fully detailed model. It’s suitable for most detailed design work.
