With fast developments in the environmental-friendly
industry,
electrically conductive adhesive (ECA) composites with high electrical
conductivity, mechanical strength, and electrochemical migration resistance
as well as low cost are highly desirable for emerging power electronics
applications. In this study, a category of ECAs, namely, size-controllable
sonochemical low-melting-point-alloy (LMPA) particle-incorporated
transient liquid-phase ECAs (TLP-ECAs), with excellent electrical
conductivity, considerable mechanical strength, and high electrochemical
migration resistance has been successfully demonstrated. Experimental
results showed that the bulk resistivity of TLP-ECA decreased to a
minimum value of 2.37 × 10–4 Ω-cm with
the remaining filler content at a low level (the total content of
metallic fillers, i.e., 70 wt % in TLP-ECAs), while the mechanical
shear strength increased considerably (by 55.4%) compared with pure
silver ECA with the same filler content, demonstrating that addition
of sonochemical LMPA particles into ECA can simultaneously and considerably
improve the electrical and mechanical properties. Moreover, the diffusional
reaction mechanism of sonochemical LMPA particle-filled TLP-ECA was
systematically investigated via differential scanning calorimetry
(DSC), X-ray diffraction (XRD), and high-resolution scanning transmission
electron microscopy in high-resolution high-angle annular dark-field
mode (STEM-HAADF). The mechanism of the diffusion reaction of TLP-ECA
with LMPA particles was rationalized, where Ag9In4 (γ phase, cP52, and P43m) and Ag3Sn (ε phase,
oP8, and Pmmm) intermetallic compounds (IMC) and their corresponding
nanostructures were responsible for the substantial enhancement in
mechanical strength and the antielectrochemical migration property.
The sonochemical method is the key to synthesize LMPA particles of
desirable compositions and controllable size, thereby enhancing the
overall performance of Ag-based TLP-ECAs. Accordingly, the sonochemical
LMPA particle-incorporated-TLP-ECAs are the promising interconnection
material candidates for power electronics packaging.