Interface Development in Cu-Based Structures Transient Liquid Phase (TLP) Bonded with Thin Al Foil Intermediate Layers

Proper bonding and assembly techniques are essential for fabrication of functional metal-based microdevices. Transient liquid phase (TLP) bonding is a promising technique for making enclosed metallic microchannel devices. In this paper, we report results of TLP bonding of Cu-based structures at temp...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2014-08, Vol.45 (9), p.3892-3906
Main Authors: Chen, Ke, Meng, Wen Jin, Eastman, J. A.
Format: Article
Language:English
Subjects:
Aluminum
Applied sciences
Assembly
Bonding
Characterization and Evaluation of Materials
Chemistry and Materials Science
Copper
Evolution
Exact sciences and technology
Foils (structural shapes)
Liquid phases
Materials Science
Mechanical properties
Metallic Materials
Metallurgy
Metals. Metallurgy
Microelectronics
Nanotechnology
Physical metallurgy
Structural Materials
Surfaces and Interfaces
Thin Films
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Summary:Proper bonding and assembly techniques are essential for fabrication of functional metal-based microdevices. Transient liquid phase (TLP) bonding is a promising technique for making enclosed metallic microchannel devices. In this paper, we report results of TLP bonding of Cu-based structures at temperatures between 823 K and 883 K (550 °C and 610 °C) with thin elemental Al foils as intermediate boding layers. In situ X-ray diffraction was utilized to examine the structure of Cu/Al interface in real time, resulting in a proposed sequence of structural evolution of the Cu/Al/Cu TLP bonding interface region. Three different types of bonding interface structures, the “ γ 1 structure,” the “eutectoid structure” (“E structure”), and the “E/ γ 1 /E structure,” were observed through electron microscopy, and related to the proposed sequence of interfacial structural evolution. Tensile fracture tests were conducted on TLP-bonded Cu/Al/Cu coupon assemblies. Hardness of the various phases within the bonding interface region was probed with instrumented nanoindentation. Results of mechanical testing were correlated to the structure of the bonding interface region. The present results provide an understanding of the structural evolution within the Cu/Al/Cu TLP bonding interface region, and offer guidance to future bonding of Cu-based microsystems.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-014-2339-5