The advantages brought by the T2PAK package for SiC power chips

New packaging solutions deliver effective thermal management and higher efficiency

To address the challenges of efficiency, size, and temperature confronting today's power system designers, effective heat dissipation has become a critical hurdle. Global markets are accelerating the adoption of Silicon Carbide (SiC) technology, yet thermal design frequently remains a limiting factor. Traditional packaging solutions often struggle to meet the thermal requirements of high-power SiC applications, forcing a trade-off between switching performance and thermal efficiency. New packaging solutions provide the effective thermal management and enhanced efficiency needed for today's more demanding applications.
 
Modern electronics face numerous challenges from electrification. Power distribution boards are often already under significant stress, frequently operating at their maximum thermal limits. Engineers cannot afford to transfer excess heat from power switches onto these boards. The D2PAK (TO-263-7L) and TO-247-4L are two MOSFET packages known for their relatively good thermal performance. However, their shortcomings become evident in space-constrained environments.
 
TO-247-4L offers adequate heat dissipation as it can be easily attached to a heatsink using a simple screw clip, providing a sufficient thermal path. However, in confined spaces, the nearby leads, conductive traces, and capacitors can form a large commutation loop, which represents the sum of all parasitic inductances. This can lead to significant voltage overshoot, reduced switching speeds, and increased switching losses.
 
D2PAK helps mitigate the stray inductance issue because, as a Surface Mount Device (SMD), its short copper traces minimize the commutation loop area. Compared to TO-247-4L, the D2PAK does enable faster switching speeds. However, D2PAK must dissipate heat through the Printed Circuit Board (PCB), resulting in higher thermal resistance between the heatsink and the device.
 
Designers need a solution that overcomes these limitations without sacrificing performance or increasing system size. Enter the T2PAK package. T2PAK combines onsemi's industry-leading Silicon Carbide technology with one of the most widely adopted Top-Side Cooled (TSC) packaging formats. Its unique design balances superior heat dissipation with excellent switching performance, merging the advantages of both TO-247-4L and D2PAK without their major drawbacks.

T2PAK's top-side cooling enables direct thermal coupling between MOSFET and heatsink

Top-Side Cooling (TSC) technology enables direct thermal coupling between the MOSFET in the SMD package and the application heatsink. This allows heat to be transferred directly from the power distribution board to the system’s cooling system or metal casing, bypassing the common PCB thermal bottleneck found in D2PAK packages.
 
The advantages of the T2PAK package’s top-side cooling technology include excellent thermal performance by directly transferring heat to the heatsink, which lowers the ambient operating temperature and reduces thermal stress. By extracting heat from the motherboard, it also decreases thermal stress on other components, helping to maintain a lower PCB temperature, extend service life, and improve system reliability. The T2PAK package offers low stray inductance; high-performance switching devices such as onsemi’s NTT2023N065M3S and NVT2023N065M3S feature extremely low total gate charge (≈74 nC) and output capacitance (≈195 pF), resulting in higher reliability and lower losses.
 
Additionally, the excellent figure of merit (FOM) of EliteSiC combined with the top-side cooled T2PAK package enables more efficient and compact application designs, providing design flexibility. The T2PAK product lineup offers a variety of options, including planned releases of 650 V and 950 V EliteSiC M3S MOSFETs with resistance values of 12 mΩ, 16 mΩ, 23 mΩ, 32 mΩ, 45 mΩ, and 60 mΩ.
 
The T2PAK package meets the IEC 60664-1 creepage distance standard, which specifies the shortest distance along the surface of the insulating material between two conductive parts (minimum 5.6 mm). The junction-to-case thermal resistance of the 12 mΩ device is as low as 0.35 °C/W (better than D2PAK), and it is compatible with liquid gap fillers, solder pads, and ceramic insulators. This allows for optimized thermal stacking and provides mounting flexibility.

T2PAK package is well-suited for demanding industrial and automotive applications

Worldwide sampling of T2PAK has been underway since 2025 in Europe, the Americas, and Greater China. This package is ideal for demanding industrial and automotive applications. For EV applications, T2PAK is often the preferred package for On-Board Chargers (OBC), drivetrain components, and EV charging stations. Since an OBC typically interfaces with the vehicle's liquid cooling system, the TSC package can channel heat from power switches into the system via a thermal conductive interface. Reducing stray inductance improves power efficiency by eliminating commutation loop issues, which lowers switching losses. Furthermore, adherence to IEC creepage standards helps strengthen manufacturers' safety commitments to customers.
 
In industrial and energy infrastructure applications, TSC packages are rapidly gaining adoption in solar energy systems due to their superior thermal efficiency. The T2PAK has proven to be an ideal choice for new and advanced infrastructure applications such as solar power conversion and Energy Storage Systems (ESS).
 
For hyperscale AI data centers, which rely on rack-mounted AC-DC and DC-DC power supplies and power distribution units, the entire architecture is built around easy access and replacement of these power units. As liquid cooling becomes commonplace in data centers, the native top-side cooling of the T2PAK integrates seamlessly with cold plate designs. In such setups, free-flowing coolant circulates through channels adjacent to thermal interfaces attached directly to the hottest chips, carrying heat away from high-performance processors. According to recent studies, combining cold plate designs with immersion cooling can reduce greenhouse gas emissions by up to one-fifth.
 
By overcoming thermal challenges, the T2PAK empowers designers to achieve higher performance, greater reliability, and simplified thermal management. Compared to traditional discrete packages, customers can realize higher power density using T2PAK.
 
T2PAK is also suitable for High-Voltage DC/DC converters (automotive and industrial), industrial Switched-Mode Power Supplies (SMPS) for automation and robotics, industrial drives, and high-efficiency DC-DC converters. As power systems evolve, future designs will increasingly rely on top-side cooling to meet stringent efficiency and size targets. onsemi is prepared to lead this development by combining its leading SiC technology with the T2PAK package.

A top-side cooled package designed for automotive and industrial high-voltage applications

To enhance its advanced power package portfolio, onsemi introduced the T2PAK and BPAK, top-side cooled packages designed to meet stringent standards for automotive and industrial High-Voltage (HV) applications. Unlike bottom-side cooled packages like D2PAK and TOLL, which must extract heat through the PCB, T2PAK and BPAK employ a top-side cooling design. This design ensures direct contact with the heatsink, significantly improving thermal performance.
 
Featuring top-side cooling and a leadless design, T2PAK minimizes stray inductance by eliminating long leads and enabling tighter current loops than D2PAK or TO packages. This results in improved switching characteristics, reduced voltage overshoot, and better Electromagnetic Compatibility (EMC) performance, making T2PAK an excellent choice for compact, high-efficiency power designs. This advancement enables higher power density, meeting the evolving needs of high-performance applications. onsemi's initial offerings in this new package type include eight EliteSiC Silicon Carbide MOSFETs, covering T2PAK Automotive Qualified products (using M3S and M2 technology for 650 V and 950 V / 900 V lines) and T2PAK Industrial Qualified products (using M3S technology for 650 V lines).
 
Both T2PAK and D2PAK (TO-263) are high-power surface-mount solutions designed for efficient thermal management in compact PCB layouts. While they have similar electrical footprints, their thermal architectures differ significantly. D2PAK is a bottom-side cooled package, relying on an exposed drain pad to transfer heat into the PCB copper layers and through thermal vias to internal or backside copper planes. In contrast, T2PAK introduces top-side cooling via an integrated through-hole tab, allowing direct connection to an external heatsink or metal chassis. This top-side thermal path provides a more efficient and controlled heat dissipation mechanism, particularly beneficial when PCB thermal capacity is limited or when forced-air cooling is available on the component side.
 
In comparison, bottom-side cooled packages rely on the PCB's bottom copper layer for heat dissipation, which restricts their use for electrical routing. This limitation complicates the implementation of a compact commutation loop, often leading to longer trace paths and higher parasitic inductance. As the bottom layer must be dedicated to heat sinking (typically using thermal vias and large copper areas), routing the return path close to the power loop becomes impractical. This reduces flux cancellation effectiveness and increases loop inductance, negatively impacting switching performance. In this regard, top-side cooled packages like T2PAK have a distinct advantage. Their thermal design allows for more flexible electrical routing, enabling a more compact and optimized commutation loop.
 
This architectural difference translates into measurable thermal performance gains. For a 32 mΩ device, T2PAK achieves a junction-to-case thermal resistance of 0.7 °C/W, slightly better than D2PAK's 0.75 °C/W. The advantage is more pronounced for lower-resistance, higher-current devices; for instance, a 12 mΩ T2PAK device exhibits a temperature rise of 0.3 °C/W compared to 0.35 °C/W for its D2PAK counterpart. These improvements are primarily due to T2PAK's ability to transfer heat directly to a heatsink, bypassing the thermal limitations of the PCB. Consequently, T2PAK is particularly well-suited for thermally constrained designs or applications requiring greater thermal headroom, such as automotive power modules, industrial drives, and high-efficiency DC-DC converters.
 
Compared to traditional SMD devices, top-side cooled packages generally offer superior thermal performance because they can extract heat directly from the exposed metal pad (drain for MOSFETs, collector for IGBTs, cathode for rectifiers) without the thermal resistance of the intervening PCB material, which is inherent in bottom-side cooled packages. Leveraging its top-side cooling capability, the T2PAK package provides a significant thermal advantage by enabling direct contact with heatsinks or cold plates, overcoming the PCB-based heat transfer limitations seen in bottom-cooled SMD packages like TO-263-7.
 
The T2PAK package is designed for reflow soldering onto PCB boards. It adheres to the IPC/JEDEC J-STD-020E reflow profile. The T2PAK package is compatible with both Tin-Lead (Sn-Pb) and Lead-Free (Pb-Free) soldering processes, each requiring distinct thermal profiles. Sn-Pb assembly uses eutectic solder alloys with a lower melting point (183°C), while Lead-Free assembly (typically using SAC305 alloy) requires a higher liquidus temperature (217°C) and peak reflow temperatures up to 245°C. Proper preheating and thermal control are crucial, especially for Lead-Free processes, to minimize thermal stress and ensure reliable solder joints.

Conclusion

As electrification reshapes industries, onsemi's EliteSiC T2PAK is redefining the possibilities in high-efficiency power conversion. EliteSiC MOSFETs in the T2PAK TSC package represent a packaging advancement that acts as a strategic enabler for electrification. By delivering superior thermal performance, reliability, and design flexibility without the usual trade-offs, T2PAK overcomes the space and thermal constraints faced by industries worldwide. onsemi's T2PAK is available to the broad market, ensuring widespread access to this critical technology.