SiCPAK™ is one of many thermal management solutions
Maintaining thermal management in electronics is a moving goal. It’s possible that any practical measure taken could become insufficient as chip design moves to the next iteration of smaller and / or faster integrated circuits. System designers will also want to reduce the size of the next generation product. Power density is an ongoing thermal design problem, demanding more robust cooling solutions.
The issue is compounded by the global trend toward higher-power operation. The automotive sector is a prominent example — electric vehicles (EVs) are moving from 400V architectures to 800V architectures.
Automotive is making the transition in power ICs from silicon IGBTs (insulated gate bipolar transistors) to the newer power ICs based on wide bandgap (WBG) semiconductors, such as gallium nitride (GaN) and silicon carbide (SiC).
Part of the reason is thermal management. IGBTs run hotter at the higher frequencies necessary to support increasingly higher-power electronics, which is one of the reasons why SiC and GaN power devices are moving in. SiC and GaN are both more comfortable than silicon operating at the higher frequencies used and are more thermally robust at higher temperatures.
Increasing power device efficiency eases the thermal strain, but GaN and SiC are already more efficient than silicon — and every incremental improvement is harder to come by.
Packaging and heatsinks have always been factors in thermal management equations, but as designers push new frontiers of power — and consequently heat dissipation — packaging becomes a more important part of the thermal solution, integral to the management of heat. Innovations in packaging and heat removal have been far more extensive than some realise. Avnet Silica’s power specialists are adept in recommending and deploying these new technologies and techniques, so we can help our customer partners make the best decisions for their designs.
LOOKING FOR SUPPORT? CONTACT OUR POWER EXPERTS
The role of packaging in thermal performance
Thermal management is critical with power ICs in particular, as physical space is almost always limited. This means not only should power IC packaging be selected with care, it should also be evaluated early in the design phase. That was true for silicon IGBTs long in use, and that need hasn’t changed with the move to newer GaN and SiC power ICs.
EVs are at the forefront of driving the demand for GaN and SiC power ICs, but the diversity in products using high-voltage battery power increases every day (for example: drones and warehouse robots and cobots). Even though GaN and SiC have better thermal characteristics than silicon, designs with GaN and SiC power ICs can still run as hot (or hotter).
Designers are increasingly opting for surface mount (SMT) power ICs. SMT packages are smaller than traditional leaded packages and so support higher component density designs. The SMT equivalents of the traditional TO-220 package include DPAK and D2PAK. Rated for 50 W and 100 W power dissipation, respectively. These packages have pads on their underside to facilitate heat dissipation directly to and even through the PCB via conductive plated via holes — coupling to a heatsink or to the assembly chassis itself can facilitate further heat dissipation if required.
Topside-cooled SMT packages are a newer option to traditional bottom-side cooling. These provide lower thermal resistance and improved device switching performance. Designers can opt for either single- or dual-sided cooling depending on the thermal demands of the application.
Technology
Power: designing solutions with power at the core
We provide you with the right insights and expertise when you need it most, so you can make the right decisions for your product, and your business.
With the ongoing shift to renewable energy and the electrification of transport and industry, the demand for higher power and greater energy efficiency in electronics is increasing. Wide bandgap technologies including SiC and GaN bring many advantages.
WBG OVERVIEWThe power quad flat no-lead (PQFN) package, for example, has multiple benefits for GaN power ICs in particular, including compact size, low parasitics for very low turn-on resistance (RDSon), and superior thermal performance. PQFNs offer numerous multi-die, multi-clip, and wire variations.
While JEDEC and JEITA standards exist for semiconductor packages, innovation is running ahead of the standards process, so many package options are not standard — at least not yet.
Higher operating temperatures lead to a corollary issue: thermal stress on the solder used to mount packages on boards. This has led to yet another innovation, this one in materials science: the development of metal pastes that are alternatives to traditional sintered materials. These metal pastes have improved thermal conductivity and higher melting temperatures. Using them is still more expensive than traditional solder and sintering techniques, but some applications will demand their use.
Advances in Power Packaging and thermal management: A snippet from Thomas Hauer's interview with electropages
The key point to make here is that the industry is moving quickly, and — by necessity — has been introducing one innovation after another for packaging SiC and GaN devices, including some that are currently considered ‘non-standard’.
As a leading supplier of power solutions, backed by a network of specialist partners and an in-house team of experts, Avnet Silica is equipped to guide customers toward the options and approaches most suited to their specific application needs.
Advancements in heatsink technologies
At the board level, there are heatsinks. These used to be as conceptually simple as anything found in the electronics industry: passive slabs of metal sometimes used in conjunction with fans to achieve convection cooling. It’s no surprise that there has been innovation in heatsinks, but the extent of innovation might be a revelation for some engineers.
The innovations start with more complex finned structures and increased surface area. These heatsink designs have enhanced efficiency, becoming more effective with carefully selected heat spreader plates and the use of elastomeric gap filling materials or pads to minimise the thermal barrier at any interfaces. New heatsink structures continue to be introduced, among them distillation or absorption columns.
A heatsink designed specifically for the AMD Xilinx Kria K26
There are many highly effective heatsinks readily available as standard parts, but custom solutions will sometimes be justified. Avnet Silica’s power specialists use sophisticated computational fluid dynamics (CFD) to model and analyse heatsink shape, size, and performance to create customised versions that achieve the heat dissipation required in a form factor to suit the application and all while keeping weight and cost to a minimum. In short, it’s an all-round optimised solution. An example is a heatsink designed specifically for the AMD Xilinx Kria K26 system on module (SOM).
Heatsink designers have also created solutions with active elements, including heat exchangers that transfer heat between fluids conveyed in channels or tubes. A newer discovery is that helical tubes help create turbulence that improves thermal transfer. Another new cooling technique involves nanofluids, a new class of materials that are proving effective for heat exchange. Designers are experimenting with adding nanoparticles (metals and metal oxides) to the nanofluids to achieve even better thermal conductivity.
This isn’t anywhere close to an exhaustive list of techniques and solutions to remove excess heat from electronic components and assemblies, and elastomeric pads, gap fillers and phase change materials also provide important options and sometimes alternatives to heatsinks.
The point is that innovation in this area is ongoing, dynamic and absolutely necessary. Avnet Silica is tracking the many developments and can advise our customers if, when, and how any of these innovations are suitable for specific projects or more widespread adoption.
Conclusion
Electronics products are now operating at voltages and currents the electronics industry has rarely had to deal with before. That is making power electronics an incredibly dynamic field. Avnet Silica and its partners have the expertise to help guide you and your design teams with your high-power projects, including the challenging area of thermal management.
Working on a power project?
Our experts bring insights that extend beyond the datasheet, availability and price. The combined experience contained within our network covers thousands of projects across different customers, markets, regions and technologies. We will pull together the right team from our collective expertise to focus on your application, providing valuable ideas and recommendations to improve your product and accelerate its journey from the initial concept out into the world.
Like what you see?
Follow us on LinkedIn
Follow our dedicated power page on LinkedIn for the latest power updates and news from our team of power experts.