An In-Depth Analysis of Power-System-in-Inductor (PSI2) Technology for Power Module Packaging

This paper provides a thorough analysis of the power-system-in-inductor (PSI²) packaging for power modules through FEA simulation and experimentation of electrical and thermal performance. To sufficiently analyze the PSI² packaging, all tests conducted compare performance of PSI² to conventional plastic epoxy packaging using identical buck power modules. PSI² uses magnetic material as both the power module packaging and magnetic inductor core to increase inductor winding size and thermal conductivity of the package. In experimental testing the PSI² package achieves 2.82% greater efficiency, 0.48W less loss, 23.9°C lower top temperature, and 3.5°C lower bottom temperature at full load compared to the plastic package. Constant loss experimentation reveals approximately one third of the surface temperature difference is the result of the PSI² improved thermal conductivity at full load.

I. Introduction

In electronic devices today, point of load (POL) DC-DC power conversion is handled by buck converters. One struggle with point of load converters is the ability to transfer heat away from the junctions in small packages. Higher switching frequencies are required to keep the size of the inductors and capacitors small to reduce the overall package size. This results in greater switching losses and requires research towards modelling and reducing thermal dissipation [1] [2] [3] [4]. Significant research has focused on developing different methods of transferring and reducing heat from integrated point of load converters [5] [6] [7] [8] [9] [10] [11] [12] [13]. Low-temperature cofire ceramic (LTCC) is used to integrate power supplies and inductors at high power [7] [8] [9] [13]. At very low power, the inductor has been integrated into the substrate of the PCB to achieve integrated power delivery [10]. Recently, research has focused on developing an integrated power module called power-system-in-inductor (PSI²) [6] [11] [12]. This system integrates passive components into the cavity of the inductor core, reducing volume and increasing thermal conductivity.