Heterogeneous Integration of Magnetic Component Windings on Ceramic Substrates

Abstract

Heterogeneous integration and the converter in package concept have been highlighted as enabling technologies to unlock the full potential of silicon carbide (SiC) and gallium nitride (GaN) devices. Control of parasitic elements in the commutation loops and passive filter integration within the power module reduces the risk of overcurrent and overvoltage stresses for the transistors and can improve the containment of high-frequency noise at source, resulting in safer operation of the whole converter. However, at present, the major limitation to filter integration is posed by the low energy density of commercial magnetic components. This article further investigates on the integration of more reliable high-power-density magnetic components within the power module structure. The proposed approach consists of bonding individual copper parts, representative of single winding turns, onto an appropriately patterned ceramic substrate, thus improving the filters thermal management. At first, an experimental comparison between different bonding techniques has been carried out based on mechanical performance. Finally, to prove the feasibility and repeatability of the proposed route, a complete inductor has been manufactured using the solder bonding technique. Both thermal tests and simulations confirmed that due to the enhanced heat exchange between the inductor and cooling system, the maximum current density can be increased above commercial standards while maintaining the temperature in a safe range for the nearby active devices.