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Indium and its alloys exhibit good service life and reliability,
and are well suited for applications such as solder
interconnections in electronic packaging. In this study, two
types of Au-In microjoints, i.e. Au/In/Au in which In foil was
used and Au/In, were prepared by either solid state
interdiffusion (SSID) or solid-liquid interdiffusion (SLID)
bondings for a single lap tensile test. Deposition of the Au
and In thin films was carried out by thermal evaporation on a
polyethylene terephthalate (PET) sstrate. It was found that the
shear strength of the Au/In microjoints is higher than that of
which using In foil, i.e. Au/In/Au. In addition, it is observed
that the fracture mode of the Au-In microjoints depends on the
types of In used. Failure of the Au/In microjoints appeared to
be along the joint-substrate interfaces, whereas it occurred
within the In foil for the other type of specimens. Examination
of the Au/In microjoints by glancing angle X-ray diffraction
reveals the presence of intermetallics In2, Au10In3, and Au9In4,
in small amount, in addition to the two major constitutent
phases, Au7In3 and Au. On the other hand, only intermetallic
AuIn2 and pure In were obtained in the Au/In/Au microjoints,
where the thickness of In is much higher than that of Au.
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