Technical Article

Semiconductor-Based Power Modules vs. Discrete Components

June 05, 2024 by Patrick Baginski

In the ever-evolving landscape of power electronics, the choice between semiconductor-based power modules and discrete components has a significant impact on the efficiency, reliability, and overall performance of electronic systems.

This article is published by EEPower as part of an exclusive digital content partnership with Bodo’s Power Systems.

 

Semiconductor-based power modules have gained prominence due to their numerous advantages over traditional discrete components. In the ever-evolving power electronics landscape, the choice between semiconductor-based power modules and discrete components significantly impacts efficiency, reliability, and overall system performance.

 

Figure 1. Flow 1 IGBT module with integrated capacitors. Image used courtesy of Bodo’s Power Systems [PDF]

 

Semiconductor-Based Power Module Advantages

Semiconductor-based power modules integrate multiple components into a single package, resulting in a more compact design compared to discrete components. Modules can easily integrate anything from capacitors to improve switching behavior and stray inductance to shunts for current measurement. Their space efficiency is crucial in size-constrained and space-limited electronic systems such as book-size frequency inverters, renewable energy systems, and uninterruptible power supplies. Semiconductors are placed to ensure small commutation loops that utilize the efficiency to its maximum and enable some features that are hard to realize with discrete components.

Another aspect is enhanced reliability. In many applications, reliability is weighted higher than price. Traditional discrete components are prone to reliability issues such as solder joint failures and thermal stress. Semiconductor-based power modules, on the other hand, are designed with advanced packaging technologies that improve thermal performance and reduce the risk of component failures. Their enhanced reliability is essential in mission-critical applications where system downtime is not an option.

Reliability includes thermal performance. Power modules often feature advanced thermal management solutions, such as direct bonding technology, to dissipate heat more efficiently. This lowers their operating temperature, extending the lifespan of the components and ensuring stable performance over time. Different DCB materials come with different thermal properties. While Al2O3 is a widely used material, AlN, for example, offers very high thermal conductivity. Because it is more fragile, Si3N4 is a good compromise of both materials.

An important topic is the simplified integration and reduction of assembly costs. Integrating discrete components requires careful consideration of component placement, routing, and thermal management. Semiconductor-based power modules simplify the integration process by consolidating multiple components into a single package. This reduces assembly costs and streamlines manufacturing, resulting in faster time-to-market for electronic systems. Several steps can be spared as modules come with electrical insulation to the heatsink, can come with a layer of pre-applied thermal interface material, and only need a limited number of screws to be mounted.

Finally, power modules achieve much higher power density compared to discrete components. By tightly packing components in a compact form factor, semiconductor-based modules can deliver more power in a smaller space. This is particularly advantageous in applications with critical power efficiency and size constraints, such as solar inverters and portable electronics like welding machines, and even more critical in embedded drive applications.

 

Figure 2. Comparing the power cycling capability of standard versus advanced solder material. Image used courtesy of Bodo’s Power Systems [PDF]

 

Comparing Mechanics

A deeper comparison between the mechanics of discrete components and power modules reveals vast differences in their handling and assembly. Modules are essentially pre-tested sub-systems. Their manufacturers guarantee that all parts shipped have passed rigorous mechanical and electrical testing. Discrete components, on the other hand, require many additional, largely manual, processes that influence their reliability: Pins need to be bent, thermal interface materials applied, and, in some cases, additional electrical isolation added to the heatsink. Components to be handled include through-hole components such as the TO-220, TO-264, etc., that need to be assembled, fixed, and soldered to the PCB before being mounted to a heatsink. They are connected to form an inverter stage, a PFC circuit, or a brake chopper. Drive applications commonly use bridge rectifiers. The challenge is always to make assembly as stress-free as possible, which can be tough, as discrete components come in different heights.

 

Figure 3. Application with discrete components and with a power module. Image used courtesy of Bodo’s Power Systems [PDF]

 

Comparing Electrical Behavior

A comparison of their electrical behavior reveals further drawbacks of discrete components. For one, discrete components cannot be positioned to perform optimally in the case of commutation paths. And, secondly, due to their physical size, discrete components require more space on the PCB and cannot be placed as close to each other as the IGBTs and diodes used in a power module. Consequently, discrete components have a lower power density than power modules.

Figure 3 highlights the differences between using discrete components and power modules in small power applications.

Moreover, parallelizing discrete components requires considering even more components, while power modules can simply be replaced with the next larger housing size. To further facilitate handling, modules can be delivered with solder pins, press-fit pins, and, on request, with pre-applied phase-change material.

Semiconductor-based power modules offer a host of advantages over traditional discrete components, from their compact design and enhanced reliability to improved thermal performance and simplified integration. As a leading player in the industry, Vincotech has contributed significantly to the evolution of power module technology. With its commitment to innovation, customization, and sustainability, Vincotech’s offerings empower electronic system designers to meet the demands of today’s dynamic and competitive market.

 

This article originally appeared in Bodo’s Power Systems [PDF] magazine.