Top-Side Cooling in MOSFETs: Superior Thermal Management Compared to PCB and Dual-Side Cooling

As power density in modern electronic systems continues to rise, efficient thermal management becomes a key factor in ensuring performance, reliability, and longevity— especially in high-power applications such as industrial drives, automotive systems, and power supplies. While bottom-side cooling via the PCB has been the standard for many years, topside cooling is emerging as a more efficient alternative. This article highlights the key advantages of topside cooling over traditional PCB-based cooling and dual-side cooling approaches.

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Traditional Bottom-Side Cooling

With bottom-side cooled MOSFETs, the heat generated by the semiconductor die is transferred through the device's drain pad to the PCB, and from there to a heat sink or thermal plane, typically via thermal via arrays.

While this method relies on having space available to place thermal vias, without them the thermal conductivity of the PCB materials plays a significant role.

However, there are several limitations associated with bottom-side cooling. Thermal resistance tends to be relatively high due to multiple interfaces — including the interfaces from the die to the package, from the package to the PCB, and from the PCB to the heat sink — and the low thermal conductivity of PCB materials such as FR4. Furthermore, heat dissipation is constrained by the PCB layout and available board space.

Dual-Side Cooling

Dual-side cooling seeks to enhance heat dissipation by enabling heat flow through both the top and bottom of the MOSFET.

While this approach offers improved thermal performance, it also introduces complexity in terms of mechanical integration and board design.