Top Cool Package for Power Discrete MOSFETs

onsemi’s Top Cool MOSFET package enhances thermal performance by exposing the drain on the top side of the device, allowing direct heatsinking and freeing PCB space for additional components. Testing of the TCPAK57 Top Cool device showed up to 11× lower thermal resistance and greater power-handling capability compared to traditional SO8FL packages. This application note explains how this enables smaller, cooler, and more efficient designs for high-power applications in automotive, industrial, and energy systems.

Application Note Overview

Power MOSFETs are key components in applications requiring efficient power management and compact design, such as automotive systems, power supplies, and industrial controls. Traditional surface-mount packages like SO8FL and LFPAK dissipate heat primarily through the PCB, limiting performance due to the board’s low thermal conductivity. This application note explores onsemi’s innovative Top Cool package, which exposes the MOSFET’s drain on the top side of the device for direct heatsinking.

Download this application note to learn how onsemi’s TCPAK57 Top Cool package delivers superior thermal performance compared to standard surface-mount devices. Through controlled testing, the TCPAK57 demonstrated up to 11× lower thermal resistance and significantly higher power-handling capability. The paper details the experimental setup, results, and methods for further optimizing performance using various thermal interface materials (TIMs) and heatsink configurations.

The note also highlights the broader design advantages of the Top Cool approach, including reduced PCB heat sharing, higher current margins, and increased flexibility for system layout and cooling strategies. Ideal for compact, high-power applications, onsemi’s Top Cool MOSFET technology enables smaller, cooler, and more efficient designs—paving the way for next-generation power electronics across automotive, industrial, and energy systems.