Novel Transient Liquid Phase Bonding for High-Temperature Automotive Power Electronics Systems

This paper demonstrates the concept and fabrication process for a novel (copper, nickel)-tin, (Cu, Ni)-Sn, transient liquid phase (TLP) high-temperature bond that exploits the addition of a pure aluminum (Al) core layer for die attachment in a power electronics power card structure. The bond quality and composition of the bond layer are characterized using confocal scanning acoustic microscopy (CSAM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The experimental results indicate that the material composition and established fabrication process enable a crack-free bond that exhibits a void fraction of 2% or less. Compared to a traditional foil-based single-layer TLP bonding system, the proposed foil-based TLP/metal laminated structure displays similar to 60% reduction in thermally induced mechanical stress built-in after fabrication, as verified through steady-state thermal stress simulations.