POWER role in thermal management.
More options, more trade-offs That shift brings greater variety, but also greater complexity. In the past, engineers could focus on a much narrower set of established package types. Today there is a wider range of topside-cooled, dual- sided-cooled and module-style options, and many package variants are advancing faster than the standards process. JEDEC and JEITA standards still provide an important framework for semiconductor packaging, but innovation is moving quickly enough that many newer package options are not yet standard.
That creates new opportunities for thermal performance and power density, but it also means package selection has a direct effect on performance, reliability, manufacturing process and cost. It can also introduce more practical design considerations around mounting, mechanics, manufacturability and the way the cooling approach is integrated into the assembly.
The same theme carries into materials and assembly. Higher operating temperatures create thermal stress on conventional solder and push it toward its performance limit. In response, metal pastes and alternatives to traditional sintered materials are emerging with improved thermal conductivity and higher melting temperatures. These approaches can improve thermal performance, but they may also lead to higher costs and greater manufacturing complexity.
Cooling moves closer to the package
At board level, the thermal path is also changing. Traditional heatsinks, thermal vias, heat spreaders, gap fillers and thermal interface materials (TIMs) remain important, but higher power density is forcing designers to think more carefully about where heat is removed from the device and how directly it can be coupled into the wider cooling system. This is one reason why top-side-cooled packages are becoming more relevant in power electronics. Instead of relying primarily on heat transfer through the PCB, the package can provide a more direct thermal route from the device to a heatsink or housing. That can reduce dependence on board-level heat spreading and give designers more freedom when working with compact, high-power layouts.
STMicroelectronics’ HU3PAK SiC MOSFET packaging illustrates this
shift.HU3PAK combines surface-mount assembly with top-side cooling through a wide thermally
18 “
conductive pad. When correctly mounted, the package offers typical junction-to-case thermal resistance (RJC) of 0.51 °C/W, a low package-level thermal resistance that supports compact, high-power designs where heat must be removed efficiently and repeatably.
That improvement is important because it moves thermal performance closer to the package decision itself. HU3PAK’s top-side cooling supports smaller heatsinks, a more compact form factor, greater design flexibility, and higher power density, while still retaining the assembly advantages of a surface-mount package. For applications such as EV charging infrastructure, photovoltaic inverters, switch- mode power supplies, UPS systems and motor drives, that gives designers another way to manage rising power density without relying solely on larger PCB copper areas or oversized board-level cooling.
Nevertheless, the thermal interface remains a design variable in its own right. Moving the heat path closer to the package does not remove the system-level design work. It changes where that work has to be done. The effectiveness of a top-side-cooled design still depends on package-to-heatsink contact, TIM selection where required, electrical isolation, mounting force, surface flatness, and assembly repeatability. If those elements are not controlled, the theoretical package advantage can be lost before the system reaches production.
This shows how cooling is no longer only a question of adding a heatsink late in the design. The cooling approach is increasingly shaped by the semiconductor package, the PCB layout, the TIM, the mechanical assembly, and the intended power level. For
SEPTEMBER 2026 | ELECTRONICS FOR ENGINEERS
For designers
working on high-power and increasingly compact systems, thermal management now needs to be treated as part of the core architecture of the design.
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designers, that makes thermal performance a system-level decision, but one that starts with component and package selection.
Conclusion: thermal design starts earlier
These types of developments point to one conclusion: as power density rises, thermal management is less about a single hot component and more about how the whole power system is designed and integrated. WBG semiconductors improve efficiency and enable higher performance, but they do not remove the need for careful thermal design. Instead, they emphasise the importance of packaging, materials, cooling strategies and making early trade-off decisions. For designers working on high-power and increasingly compact systems, thermal management now needs to be treated as part of the core architecture of the design. The ability to move heat effectively is directly linked to reliability, manufacturability and achievable power density.
Overcoming this challenge depends on access to the right expertise and components. This is where Avnet Silica can help. Backed by a network of specialist partners and an in-house team of experts, Avnet Silica is positioned to guide customers toward the options and approaches best suited to their application needs. This support goes beyond selecting components to the wider decisions around packaging, cooling, and implementation, all of which are becoming more important to thermal performance. For teams working on high-power projects, that means access to practical guidance drawn from experience across different customers, markets, regions and technologies.
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