Content last revised on November 21, 2025
## SK35GAL12T4: Engineering a Compact and Reliable Boost Chopper for High-Performance Power Systems
Product Overview: SK35GAL12T4 IGBT Module
Optimizing Power Density Through Advanced Thermal Engineering
The SK35GAL12T4 from Semikron is a high-reliability IGBT module engineered to maximize thermal efficiency and power density in demanding applications. Leveraging Trench4 IGBT technology, this module provides a robust solution for power conversion systems requiring precise control and long-term operational stability. It integrates a 1200V IGBT and a CAL4F freewheeling diode in a boost chopper (step-up converter) configuration. Key specifications include a nominal collector current of 50A at a case temperature of 25°C, a low saturation voltage (VCE,sat) of 1.9V (typical), and an exceptionally low thermal resistance from junction to case (Rth(j-c)) of 1.4 K/W per IGBT. This focus on thermal management ensures efficient heat dissipation, which is critical for maintaining performance under load. What is the primary benefit of its compact SEMITOP design? It enables simplified one-screw mounting and superior heat transfer, reducing assembly time and improving system reliability.
Application Scenarios & Value
Achieving System-Level Benefits in Industrial Power Conversion
For engineers designing compact power factor correction (PFC) stages or switched-mode power supplies, managing thermal load is a primary challenge. The SK35GAL12T4 directly addresses this by providing a low thermal resistance path for heat to escape. Its design, featuring a Direct Copper Bonded (DCB) aluminum oxide ceramic substrate, ensures efficient heat transfer away from the semiconductor junctions. This is not just a marginal improvement; it directly translates into tangible system-level benefits. A lower operating junction temperature enhances the module's lifespan and allows for the use of smaller, more cost-effective heatsinks, thereby increasing the overall power density of the end equipment, such as a Variable Frequency Drive (VFD). Best fit for designs up to 20 kVA, the SK35GAL12T4's thermal performance provides a critical design margin in space-constrained industrial applications. For systems requiring a full six-pack topology for three-phase motor control, the related SK35GD12T4 offers a similar current rating in a complete inverter configuration.
Key Parameter Overview
Critical Specifications for System Design & Simulation
The technical specifications of the SK35GAL12T4 are tailored for robust performance in high-frequency switching applications. The following table highlights the key parameters that are essential for thermal analysis, efficiency calculations, and gate drive design. The positive temperature coefficient of VCE,sat is a crucial feature that aids in the parallel operation of multiple modules by naturally promoting balanced current sharing.
| Parameter | Symbol | Value | Conditions |
|---|---|---|---|
| Collector-Emitter Voltage | VCES | 1200 V | Tj = 25 °C |
| Continuous Collector Current | IC,nom / IC | 35 A / 50 A | Tcase = 80 °C / 25 °C |
| Collector-Emitter Saturation Voltage | VCE(sat) | 1.9 V (typ.) | IC = 35 A, Tj = 25 °C |
| Thermal Resistance, Junction to Case | Rth(j-c) | 1.4 K/W (per IGBT) | - |
| Short Circuit Withstand Time | tpsc | 10 µs | VCC = 800 V, VGE ≤ 15 V |
Download the SK35GAL12T4 datasheet for detailed specifications and performance curves.
Technical Deep Dive
The Engineering Behind the SEMITOP® 2 Package
The performance of an IGBT module is as much a function of its packaging as its silicon. The SK35GAL12T4 is housed in the SEMITOP® 2 package, which is engineered for both manufacturing efficiency and thermal performance. The single-screw mounting mechanism simplifies assembly, reducing labor costs and ensuring consistent mounting pressure, which is vital for a low-resistance thermal interface. Internally, the use of a DCB substrate provides excellent electrical isolation while offering a thermal conductivity far superior to traditional insulated metal substrates. This can be thought of as creating a multi-lane highway for heat to travel from the chip to the heatsink, in contrast to a single-lane country road. This efficient "highway" is what enables the module to handle significant power in such a compact footprint without compromising its Safe Operating Area (SOA).
Frequently Asked Questions (FAQ) about the SK35GAL12T4
How does the positive temperature coefficient of VCE,sat benefit system design?
This characteristic means that as an IGBT chip heats up, its on-state resistance slightly increases. In systems where multiple IGBTs are connected in parallel to handle higher currents, this feature helps prevent thermal runaway. The warmer, more resistive IGBT will naturally conduct slightly less current, allowing cooler devices to take more load, leading to a stable, self-balancing system without complex external circuitry.
What is the significance of the CAL4F diode technology?
The "Controlled Axial Lifetime" (CAL) diode is a soft-recovery freewheeling diode developed by Semikron. The CAL4F (Fast) version integrated into the SK35GAL12T4 is optimized for low reverse recovery losses and reduced voltage overshoot. For a boost chopper, this means lower turn-on losses in the IGBT, improved EMI performance, and higher overall system efficiency, particularly at higher switching frequencies.
Is this module suitable for applications requiring high short-circuit robustness?
Yes, the module is specified with a short-circuit withstand time (t_psc) of 10 microseconds. This is a critical safety parameter, indicating the duration the device can withstand a direct short circuit across its terminals before failure. This 10 µs rating provides a sufficient window for the system's protection circuitry (e.g., the gate drive with desaturation detection) to safely shut down the IGBT, preventing catastrophic failure and enhancing the reliability of the overall power converter.
Strategic Component Selection
A Foundation for Future-Ready Power Electronics
Integrating the SK35GAL12T4 is a strategic choice for developing power systems that are not only efficient and reliable today but also aligned with future trends towards greater power density and simplified manufacturing. Its combination of proven Trench4 IGBT silicon and advanced thermal packaging provides a dependable building block for a wide range of industrial power conversion systems.
