Round table: Thermal challenges & 2020 trends in LEDs
01 May 2020
Thermal analysis is constantly evolving. Computational fluid dynamics (CFD) and thermal design, modelling & simulation expert, Future Facilities prides itself on staying at the cutting edge of the trends & technologies that will drive the future of its sector.
This article was originally featured in the May 2020 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.
Chris Aldham, Product Manager for Future Facilities’ electronics thermal modelling software, 6SigmaET tells us how, as part of its Thermal Focus research series, the company recently put LEDs in the spotlight to discover the direction this increasingly popular technology is headed – and the thermal complications that will inevitably follow...
To gain a comprehensive understanding of the intricacies of LED designs, 6SigmaET hosted a round table discussion with a panel of thermal experts from leading LED & lighting firms: R&D Manager, Genevieve Martin from connected LED lighting systems experts, Signify (formerly Philips Lighting); founder & owner, Norbert Engelberts from engineering consultants in thermal management for electronics (including LED lighting), Optimal Thermal Solutions; and founder & Managing Director, Ad Musters from cooling technologies for electronics (including LED lighting) specialists, Thal Technologies. So, let’s reveal the key trends – and resulting thermal challenges – that LED engineers will face in 2020...
Electronic devices are becoming more compact – in both consumer and industrial applications. As a result, designers are adopting innovative techniques in order to integrate LEDs into all form factors of light bulbs, including spotlights, strip lighting and LED filaments.
As one example, many engineers are now specifying LEDs as chip-scale packages (CSP). CSP implies an architecture in which there is virtually no package beyond the electrical p and n contacts that are metallized in the back-end manufacturing process. The result is a far smaller surface area, with significantly less real estate around the chip. This means that CSPs can be placed really close together, creating extremely power-dense modules within ever-smaller overall designs.
Of course, the downside of this is that such close groupings of high-powered LEDs will inevitably generate significant heat. In some cases, LED size can be as little as 1mm 2 , despite generating over a watt of power. In ever-smaller devices, with no packaging around the LED, excess heat inevitably builds up, leading to thermal complications. This can put devices at risk of overheating, limiting the reliability of the design.
“If you put these small chips just on the FR4 board, the potential for thermal complications really increases, because the power density is so high,” says Norbert Engelberts. “It’s a huge challenge to try and solve that problem.”
To overcome this, design engineers working with LEDs are turning to increasingly advanced and more precise methods of thermal simulation. Working with such small components, today’s thermal simulation platforms must offer a far higher degree of accuracy, exploiting even the smallest opportunities to safely transfer heat away.
Decreased design time
Another key trend identified by the panel was dramatically shrinking time-to-market, across the whole electronics industry. Both LED manufacturers and device designers are now being driven to deliver to ever-shorter timescales. In the case of one LED professional on the panel, turnaround time for an entire LED design project could be as little as two weeks.
With growing pressure to go to market quickly, there is a tendency for designers to assume that the latest innovations will automatically be the ‘best’ for their designs. This is, however, rarely the case. To guarantee reliability, components must be carefully selected to ensure that they do not use excess power, and they dissipate heat effectively.
“LEDs are a dynamic and competitive product area, and the market has really changed recently,” explains Genevieve Martin. “There’s a low barrier to entry, but that means perhaps products aren’t always being designed in the optimum way.”
Once again, thermal simulation tools present a key solution. By digitally creating a design through simulation before producing a physical prototype, designers can trial different component types until they find those that are best suited to their unique thermal and power requirements.
Unfortunately, time-to-market pressures are also limiting the effective use of thermal simulation, with research from 6SigmaET showing that over a third of design engineers don’t spend enough time simulating their designs before they go to market.
Sub-optimal designs can lead to product failures, poor light output or long-term reliability issues. It’s vital that time is factored into the initial design processes to adequately account for possible thermal complications.
The IoT & expanding use cases
Because of their flexibility and energy efficiency, LEDs are now being incorporated into a wide range of products – from ‘smart’ home lighting to car headlamps and beyond.
This is great news for end-users. However, LED designers rarely know which application their product will be used in. The rise of the IoT means LEDs can find themselves encountering a variety of different climates and environments, making it virtually impossible to predict the thermal conditions the design will have to withstand.
Our panel noted that this situation is further complicated by the fact that, though traditional lighting solutions have a maximum junction temperature of around 2,000°C, LEDs need to be closer to 100°C to achieve their desired lifetime. This means there’s a greatly reduced margin for error when designing LED products.
“In the past, I thought LED headlights would be impossible, but we’re beginning to see use cases like that now,” reveals Ad Musters. “With all these innovative new integrations of LED technology, thermal complications will be the major concern.”
LEDs will now be used in a whole new array of environments. Many of these environments could involve high altitudes, extreme hot or cold temperatures, or even temporary or permanent water submersion. As such, attempting to predict performance and reliability, considering airflow and heat dissipation, has never been harder.
Clearly, implementation of LED technology will only continue to increase in the coming years – since they have numerous advantages over traditional legacy lighting solutions.
So, given the increasing ubiquity of LEDs in our personal and working lives, how can designers and engineers overcome the challenges our experts identified?
A common theme that our panel touched upon was the need for comprehensive thermal simulation of LED products.
Thermal simulation gives you a unique visual representation of the temperature and airflow inside equipment. This allows engineers to make better decisions when it comes to offsetting heat and design a cooling system that balances performance and cost.
“From my team’s perspective, in 2020 we will look to provide insights at a faster rate and optimise our products as efficiently as possible,” concludes Genevieve Martin. “Deploying new working systems and tools is an essential part of this process – with simulation a high priority.”
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