Semikron SKR 320/08

Content last revised on October 23, 2025.

SKR 320/08 Diode: Engineering Review of a 320A/800V Fast Recovery Rectifier

An Engineer's Introduction to the SKR 320/08

The SKR 320/08 fast recovery rectifier diode is engineered for superior thermal stability and long-term reliability in high-current applications. It delivers a robust specification set—800V | 320A (Tc=100°C) | Rth(j-c) 0.12 K/W—built upon a proven mechanical platform. Key engineering benefits include a highly efficient stud-mount thermal path and a hermetically sealed case for resilience in harsh industrial environments. This device directly addresses the critical need for a high-current rectifier that maintains performance integrity under demanding thermal loads and frequent power cycles. For high-current industrial rectifiers demanding robust thermal management and field reliability, the SKR 320/08's stud-mount design is the definitive choice.

Key Parameter Overview

Decoding the Specs for Thermal and Electrical Performance

The technical specifications of the SKR 320/08 are optimized for high-power rectification and freewheeling applications. The parameters below are grouped by function to facilitate system-level design and analysis. What is the primary benefit of its stud-mount design? A direct, low-resistance thermal path for superior heat dissipation.

Note: These parameters represent a selection of key values. Full electrical and thermal characteristics, including performance curves, are available in the official product datasheet.

Download the SKR 320/08 datasheet for detailed specifications and performance curves.

Application Scenarios & Value

Achieving System-Level Reliability in Demanding Power Systems

The SKR 320/08 is engineered for applications where electrical robustness and thermal endurance are non-negotiable. Its primary value lies in its ability to provide stable, long-term performance under heavy electrical and thermal loads.

• Welding Power Supplies: In high-current welding equipment, rectifiers must endure continuous high currents and significant thermal cycling. The SKR 320/08's low thermal resistance allows for efficient heat extraction via a heatsink, while its high surge current rating (IFSM) of 5500A provides the necessary headroom to survive the demanding arc-striking phase, ensuring the longevity of the power supply.
• High-Power Rectifiers: For industrial applications like electroplating, battery charging, and DC motor drives, reliability is paramount. The hermetically sealed metal and glass construction protects the semiconductor junction from industrial contaminants and moisture, preventing long-term degradation and ensuring consistent DC output.
• Freewheeling Diode Applications: In large motor drives and chopper circuits, the fast recovery characteristic (trr) is critical for minimizing switching losses and protecting the primary switching device (e.g., an IGBT or thyristor). The SKR 320/08's performance enables higher system efficiency and reduces thermal stress on associated components.

While the SKR 320/08 provides a single high-power diode solution, systems requiring a pre-packaged common-cathode or common-anode pair might consider the SKKD162/16, which offers a 1600V rating in a dual-diode module configuration for simplified assembly.

Technical Deep Dive

The Engineering Advantage of Stud-Mount, Hermetic Construction

The fundamental design of the SKR 320/08 sets it apart from conventional plastic-encapsulated power modules. Its stud-mount, hermetically sealed architecture is a deliberate engineering choice focused on maximizing long-term reliability and thermal performance. The threaded stud (M24x1.5) serves a dual purpose: it provides a secure mechanical anchor and creates a direct, high-pressure, low-resistance path for both electrical current and thermal energy. Think of it as bolting a critical component directly to the system's chassis for maximum stability and heat transfer, rather than relying on intermediate layers that can degrade over time.

This construction method entirely sidesteps a common failure mechanism in power electronics: solder fatigue. In conventional modules, repeated heating and cooling cause expansion and contraction of different materials, which can lead to cracks in the solder layers over thousands of cycles. By using a pressure-contact design, the SKR 320/08 ensures a consistently reliable connection throughout its operational life. Furthermore, the glass-to-metal hermetic seal provides an impermeable barrier against humidity, dust, and corrosive gases found in industrial settings. Why is the hermetic seal important? It prevents contamination, ensuring long-term electrical stability and predictable performance for years of service.

Frequently Asked Questions (FAQ)

How does the SKR 320/08's stud-mount and hermetic seal contribute to system reliability compared to standard power modules?

The stud-mount design creates a direct, high-pressure contact that eliminates solder layers, a primary point of failure from thermal cycling fatigue. The hermetic seal provides an impermeable barrier against environmental contaminants like moisture and dust, which can cause electrical parameter drift and premature failure in non-hermetic plastic modules. This combination results in a significantly more robust and longer-lasting component, especially in harsh industrial environments.

What is the practical implication of the 0.12 K/W thermal resistance from junction to case (Rth(j-c)) for a design engineer?

This low Rth(j-c) value is a direct measure of how efficiently heat can be transferred from the active semiconductor junction to the device's case. For an engineer, it means that for a given amount of power dissipated, the junction temperature will remain lower. This directly translates to two key benefits: 1) Increased reliability and longer component life, as operating at lower temperatures reduces stress on the silicon. 2) The ability to use a smaller, less costly heatsink for a given power level, which can reduce the overall size, weight, and cost of the final system.

Evaluating the SKR 320/08 for Your Design

To assess the suitability of the SKR 320/08 Fast Recovery Rectifier Diode for your specific high-reliability power application, please use the "Request a Quote" form on this page. Our team can provide further details to support your engineering and procurement process.