Cool Runnings: How Multiphysics Simulation is Rewriting the Rules of Electronics Thermal Design

In February 2024, the U.S. Consumer Product Safety Commission announced a recall of over 15 million laptop adapters, due to fire and burn hazards caused by overheating. It's just the latest in a stream of similar safety alerts. Recently, products as diverse as baby monitors, air fryers, and massage guns have all been subject to recalls because of overheating concerns. For electronic designers, such incidents underline the importance of effective thermal management.

But it's an increasingly tough ask. As products become more complex, traditional approaches to thermal design are struggling to keep pace. In worst-case scenarios, the result of outdated approaches to thermal management is critical failure. Even when problems are less severe, ineffective thermal analysis and design processes compromise safety and performance while adding unwanted time and cost to development. Fortunately, as design teams look for answers, the latest multiphysics, multidisciplinary simulation environments are enabling a complete reboot. These advanced tools democratize thermal management and bring unprecedented speed and simplicity to even the most complex thermal management challenges.

Keeping Your Cool

The basic principles of thermal design are straightforward. Each component within a product has a safe range of operating temperatures. Designers must ensure components don't exceed these parameters within their intended systems and environments. As an extreme example, the surface of a space shuttle re-entering the earth's atmosphere can reach 2,732 F (1,500 C) - though it seems scorchingly high, this is safe for the material that covers shuttles' surfaces. Design teams must address the fact that a logic chip might experience the same heat flux, or flow of heat, but have a safe temperature limit of just 257 F (125 C), requiring significant cooling. As a more routine example, many people have experienced the realities of thermal management firsthand when their cell phones shut down after sitting too long in a windowsill or vehicle on a hot, sunny day. That shutdown mechanism protects the phone's internal components when they exceed their safe operating temperature. If it kicks in too late, there's a significant risk of damage. If it cuts in too soon or too often, it compromises the user experience.

The need for thermal management is nothing new. Neither are harsh operating environments. However, electronic product design is now characterized by increased design complexity and faster product innovation. Customers expect more functionality and performance from ever more compact designs. More power is flowing through components that are packed more densely together. Temperatures inside these cramped physical spaces are rising, yet designers often have less freedom to adjust component layouts.

The problems don't end there. The components within modern systems are also becoming more diverse. That means dozens of different materials need to be considered, not to mention hundreds of different loads. Individual components not only have different operating temperature ranges, they also present different dynamic heat dissipation characteristics as operating temperatures rise. Adding to the complexity, the variety of cooling solutions is expanding, including air, liquid, and mixed air-liquid cooling methods.

The Old School is Out

In many cases, design teams aren't well-placed to handle and test thermal management issues. Traditionally, there's been a tendency to rely on experience and "gut feel." But old-school techniques are falling short. In addition, in many organizations, traditional workflows require a team dedicated to packaging to pass their designs on to a team dedicated to thermal management. As thermal management becomes more challenging, that results in a rinse-and-repeat scenario that kicks designs back and forth between teams before a solution emerges. This process can add weeks to the timetable. With time to market now an overriding priority, the need for change is obvious.

That's precisely where advanced multiphysics and multidisciplinary simulation comes in. As the names suggest, these tools can handle solid parts, electrical thermal behavior, and computational fluid dynamics (CFD) within the same environment - and effortlessly model the entire range and complexity of factors and variables involved. Altair® SimLab®, a process-driven electronic systems design (ESD) environment, can handle all these requirements, including materials, loads and cooling systems, and other critical physics. For example, components are not treated as monolithic "cubes." They have internal structures, and their behavior is captured to ensure accurate thermal simulations. It's essential to accurately and reliably simulate the different forms of heat transfer, such as conduction, convection, and radiation to validate designs early in the design cycle.

But handling complexity is only one part of the battle. Many electronic design teams have little or no experience in areas like CFD. In the race to deliver better products to market faster, designers need solutions like SimLab that provide intuitive, accessible simulation workflows. SimLab users can be productive within days and create complex thermal models of electronic devices, even if they're not CFD analysts or thermal designers.

The key lies in SimLab's unified interface and dedicated process-orientated workflows. Models can be imported without time-consuming meshing and geometry setup. Design modifications can be applied and assessed quickly. Little is required of the user in terms of inputting parameters thanks to advanced, behind-the-scenes algorithms that manage most settings and calculations. And an intuitive GUI ensures that ease of use is combined with exceptional granularity in terms of results' detail and accuracy.

Trusting the Process

Sophisticated, accessible thermal simulation opens the door to new development pathways. Electronic designers and packaging teams can take far greater responsibility for thermal management, putting an end to inefficient back and forth with their thermal colleagues. In many organizations, thermal design is under-resourced. These tools ease bottlenecks by enabling more people to undertake rapid thermal simulation and subsequent design modifications. And because more people have more headroom to run different design iterations within a collaborative environment, identifying optimal solutions is both quicker and easier.

Alongside greater speed, this approach offers far more accurate thermal simulation than traditional methodologies. For starters, simulation minimizes the need for physical prototyping and testing. Further down the line, when products reach the market, it also minimizes the risk of overheating, mission critical failures, and issues with performance, reliability, and safety. Manufacturers and designers therefore benefit from more robust protection against product recalls, higher warranty claims, and reputational damage.

Accurate, trusted simulation also eliminates the need to over-engineer. Faced with growing thermal complexity, some organizations have resorted to much wider safety margins. Inevitably, that carries an engineering cost, undermining the product's competitiveness and/or profit margin. With accurate thermal simulation tools at their disposal, design teams can confidently work to more sensible parameters.

Converging Trends

The growing adoption of multiphysics simulation to solve thermal challenges reflects a bigger picture. Successful electronic product development increasingly demands a fully integrated design methodology. Each design requirement of the process - from thermal management to structural reliability to CFD evaluations and more - needs to share the same collaborative design environment. Moreover, to avoid the cost and delay of late design changes, simulation should be performed early in the design stage. SimLab is a product of this philosophy. As part of the Altair® HyperWorks® simulation and design platform, SimLab is but one of many tools designers can access within the same flexible and efficient licensing ecosystem. For designers grappling with current ESD thermal challenges or other multiphysics design requirements, SimLab is the best, easiest solution in the quest for cooler solutions.

To learn more about SimLab, visit https://altair.com/simlab.

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