Why choose custom power modules from Prodrive Technologies instead of off-the-shelf solutions?

A range of standard power modules is already available off-the-shelf, but there is now an emerging trend towards choosing power modules that are designed specifically for each application.

What many people don’t realize is that the power modules used in so many power conversion products largely determine its lifetime and reliability. Manufacturers are therefore faced with a choice between performance, cost, and dependability based on the power module.

A range of standard power modules is already available off-the-shelf, but there is now an emerging trend towards choosing power modules that are designed specifically for each application.

What is driving growth for custom power modules?

Most product manufacturers have, until now, sourced generic power modules that are “OK” for the application, but always require some sort of compromise. In many cases, they need to overdesign a solution to achieve the desired power. The best a customer can aim for in this scenario is to select a solution requiring the least amount of dies (power transistors), leading to cost savings, or where the modules are more reliable and long-lasting.

However, what we have seen is growth in several areas where manufacturers are realizing the potential of a customized power module solution for their products.

Several possible applications are driving this demand:

- Pulsed power – this includes products such as amplifiers, linear drives, and power tools

- Continuous high power- items like a traction inverter or solid-state transformer

- Extremely reliable power – satellites, aerospace industry applications, and UPS (uninterruptable power supply) backup units for computing all depend on this

This need is further cemented by other factors affecting the power market more generally. Semiconductor performance is increasing fast (driven by the transition from Si to SiC and GaN), and the packaging is becoming a limiting factor to getting the highest performance out of these dies.

Generic power modules are not problem-free

It is a fact that power modules suffer from thermal stresses whenever they are switched on or off (i.e. they heat up). The dies in modules can dissipate a significant amount of heat which leads to the materials in the package heating up rapidly and cooling.

The thermal swing causes stress in and between the materials because their coefficients of thermal expansion typically don’t match. This is one of the main reasons that power modules will fail in time and is, therefore, a driving force for manufacturers in seeking custom solutions tailored to tackle their particular use case.

How to optimize power modules

There are multiple routes for optimizing the die packaging in highly integrated power modules. Such as:

- Integrating decoupling and snubbers

- Integrating the gate driver

- Utilizing a kelvin source terminal

- Mechanical optimization of die attach layers

- Tuning thermal behavior with insulation and heat spreaders

- A combination of multiple solutions

Integration of electrical components into the module

On the electrical side, integrating components into the module, which are typically found on PCBs (printed circuit boards) outside the module, allows critical parameters to be optimized. For example, integrating the decoupling and snubbers enables the optimization of the power loop.

Meanwhile, integrating the gate driver and utilizing a kelvin source terminal allows for optimal gate drive loops, leading to higher efficiency and less ripple.

Mechanical optimization to exceed off-the-shelf solution performance

Mechanical optimization can be done through the choice of die attach layers, insulating materials, and heat spreaders, for example, in order to tune the thermal behavior of the module and greatly increase cycles-to-failure compared to standard solutions.

These solutions can lead to higher lifetime or higher power density when using the same die, or alternatively to lower cost for the same performance by using lower rated dies.

At Prodrive Technologies, we combine multiple solutions in our own custom Si IGBT and SiC MOSFET power modules.

Customized power modules help you make better products

By selecting a technology based on the application, it is possible to optimize the performance, reliability, and cost target for each module. Custom power modules are also typically more compact as they are designed specifically for an application, offering the shortest loops for the smallest parasitics. The much smaller commutation loop that Prodrive Technologies can achieve is largely possible by smart integration of the passive components into the module.

For our customers, this means they can produce and market a superior product that’s more reliable at the right price while minimizing design effort and time-to-market. For instance, where two standard power modules are normally used together, challenges related to balancing are introduced. Instead, a single customized solution could be used. This typically reduces overall cost.