Q: As requirements increase for smaller, high performance power supplies and modules, what steps are you taking to ensure thermal management needs are met in these products?
By Mitch Polonsky, senior product marketing manager, Mixed-Signal and Linear Division (MLSD), Microchip Technology
Microchip has been reviewing two major ways to solve thermal management challenges smaller, higher-performance power supplies, and modules: packaging and adding special on-chip functions.
In the area of packaging, Microchip has introduced chip-scale packaging (CSP) that can be incorporated into modules. This has worked for products like a local temperature sensor as it comes in a four- or five-ball version. For slightly more standard packaging, we are using a 2 x 2.5 mm VDFN package for products like the five-channel temperature sensors. This is a relatively new package for the JEDEC Solid State Technology Association. What makes this a nice package for power supplies is that it adheres to lower cost manufacturing methods by keeping to a 0.5 mm spacing. What is new is the ability to have a 10-pin footprint with only a total length of 2.5 mm in a dual in-line package. This was not available several years ago.
Adding specialized functionality is also a powerful way to help solve thermal management challenges. Because Microchip’s multichannel temperature sensors include up to eight readings, they beg for an easier method to poll all the temperatures. This is solved with the ‘hottest of many’ approach—a single temperature register can be designated as the most extreme can even be ignored. With the addition of rate-of-change reporting to these devices, Microchip has also been able to employ an alert structure and measurement that will report on the rate of increasing or decreasing temperature. This reporting can act as a preemptive alert about thermal issues for systems that are less sophisticated, or serve as another layer of protection
By Ugo Ghisla, director of applications, Vicor
Over the last 30 years, converter power densities have been increasing at the pace of one order of magnitude per decade. While increased converter efficiencies have contributed to a decrease in the total heat dissipation, this decrease happened at a significantly slower pace, leading to a large net‑increase in heat densities.
The higher heat densities are making it more and more challenging to thermally manage high power applications, and simply increasing efficiency within existing systems and packages is not sufficient any longer. Air cooling, which has been the de-facto standard cooling method for power electronic converters from the beginning, is starting to show its limits across most applications, and it has already become obsolete for advanced technologies and cutting-edge applications like artificial intelligence (AI). For these applications, advanced packaging that maximizes thermal dissipation and is compatible with different cooling strategies is essential to ensure a successful deployment.
As such, system designers are increasingly seeking out packaging options that provide low thermal impedance from both top and bottom of the package, and preferably near-identical thermal impedances from the top and bottom of the package, to ensure even sharing of the thermal load in dual-sided cooling applications. This allows for effective dual-sided cooling for high-power and high-density applications, and the flexibility of cooling either side of the package for less heat-dense applications that only require single-side cooling. Additionally, effective packaging needs to be compatible with different cooling interfaces. Packaging characterized by planar surfaces can enable compatibility with advanced cooling methods like cold-plate liquid cooling and immersion cooling, while also retaining the ability to operate in the air-cooled environment (perhaps equipped with additional heat-sinking if necessary). These advanced power component packaging techniques that are compatible with multiple cooling methods are top of mind for system designers alike as the industry evolves to keep pace with continued, rapid gains in power converter densities for AI applications and beyond.