Quantification of Thermal Resistance of Transient Liquid Phase Bonded Cu/Al/Cu Interfaces for Assembly of Cu Based Microchannel Heat Exchangers

Abstract

Transient liquid phase (TLP) bonding of Cu structures with a thin elemental Al intermediate bonding layer is being used to assemble Cubased, enclosed, microchannel heat exchangers (MHEs). The heterogeneous Cu/Al/Cu TLP bonding interface region, formed during the TLP bonding process, impacts heat transfer of the assembled MHE device. To evaluate the thermal resistance of TLP bonded Cu/Al/Cu interface regions, transient flash measurements were performed across bonding interface regions formed under various conditions, in combination with detailed structural examination and measurements of bulk mass density and specific heat. The flash method is shown to yield quantitative measurements of interfacial thermal resistance values. Our results provide guidance to developing bonding protocols for Cubased MHEs with optimized heat transfer performance.