5 Common Misconceptions about Thermal Design

19 July, 2018

Miniaturisation has always been at the heart of the electronics industry. But, with the constant demand for shrinking devices comes a lot more unwanted heat being generated in ever-decreasing spaces. The smaller the devices get, the more heat-conscious engineers need to be.

However, for many design engineers, thermal issues are considered a low priority – and are often neglected. This short-sightedness ignores the major headaches that can be caused further down the line by poor thermal design – often resulting in costly late stage fixes.

If designers are to avoid these late stage pitfalls they will need to put careful consideration into thermal design and this will often require simulation alongside prototypes.

There are a number of common misconceptions about thermal design that need to be overcome. Here are my top five:

Busting Myths

1. It’s all about keeping things cool

Thermal design is really about ensuring that a device is kept within an optimal temperature window in order to run efficiently and effectively. So, while many engineers may look to reduce the overall temperature of their products to avoid them overheating, some engineers might actually look to heat their products up to compensate for the environment that the device operates in i.e. outdoor applications in cold climates.

2. Thermal design is not a priority and needs to be performed by mechanical engineers after electronics engineers have finished their design

Even though mechanical engineers have a strong knowledge of physics and thermodynamics, the role of thermal design need not exclusively be their responsibility. Most engineers understand the role of temperature and, with the right tools, can figure out if something is getting too hot. More often than not, this is discovered late in the process, often resulting in costly design changes. According to research, 40% of design engineers consider thermal design a “low priority” when developing their devices. For many, their top priorities include ensuring product reliability, complying with regulations and innovating new features. But the irony of this is that accurate thermal design allows you to achieve all of these things. If engineers considered thermal issues in the very early stages of their designs, they would be able to stop products from overheating and ensure that their designs remain reliable and comply with strict safety regulations. On top of this, by cutting down on power consumption and space (e.g. designing out unnecessary fans), thermal design can free up opportunities for new components and innovations within an end product.

3. Everything can be fixed with a fan or a heat-sink…

Two of the most common go-to solutions for an overheating component are to simply “stick an extra fan here” or “put a heat sink on top of that”. However, as solutions go, adding a fan can actually be counter-productive because designers are just piling more components into an already over packed casing, which adds to the overall cost of materials, and increases the energy consumption of the device. In the case of using a heat-sink, the reality is that they are in fact ‘heat moving devices’ rather than something specifically aimed at absorbing heat. Even though the heat-sink may cool the component it is sitting on, it won’t just absorb the heat as it will also need to distribute the heat into the air around the heat sink. Despite many thinking that these are simple quick fixes to an overheated device, the reality is that if the layout and airflow of the device has not been designed properly, then adding a fan or a heatsink may not actually deliver the necessary cooling for the components and create new unforeseen problems…

4. Thermal simulations are complex and can only be conducted by the experts

As the process of thermal design has evolved, so too have the tools required to conduct and perform accurate thermal simulations. Back in the day,  engineers needed to develop models and simulation scenarios themselves. But now, much of this work can be imported through CAD and is automated within the software. Gone are the days where engineers needed to invest in heavy-duty hardware to conduct simple simulations. Today’s engineers benefit from the ability to export designs and simulations to cloud-based servers for maximum solving speeds. With the improved user interfaces of modern simulation suites, engineers no longer need to have an extensive knowledge of thermal design or CFD in order to manage the heat flow of their designs.

5. Thermal simulation tools are all the same

Technically speaking, all thermal simulation software uses a very similar approach, with many of the tools available on today’s market remaining largely unchanged over the last twenty years. The thinking behind this is that if the physical laws and equations related to heat flow haven’t changed, then why is there a need for the software to change. This premise has resulted in a number of packages that are dated and do not provide the intuitive interfaces and levels of automation that design engineers today expect. Instead of treating thermal simulation as a set-in-stone process, engineers should take this opportunity shop around and trial different tools before deciding which one is best suited to their project, device or working style. 

By: Chris Aldham, Product Manager