Abstract :
Aluminum nitride (AlN) is an attractive
substrate material for electronic packaging applications
because of its high thermal conductivity and
electrical resistivity. However, improved metallization
of aluminum nitride is required for reliable conductivity
and good adhesion to the ceramic substrate. In
this study, the kinetics, microstructure, and mechanical
strength of Ag–Cu–Ti/AlN reaction couples have been
studied in the temperature range of 900–1,050 C and
hold time range of 0–1.44 · 104 s using a eutectic silver–
copper filler alloy containing titanium within the
range of 2–8 wt%. The product layer thickening
kinetics has been observed to change from a linear to
non-linear thickening mechanism with the increase in
holding time and temperature. At shorter hold times at
a fixed temperature, the interfacial product layer followed
a linear thickening kinetics. With the increase in
the hold time, the thickening kinetics of the interface
followed a non-linear thickening behavior. The nonlinear
thickening mechanism has been approximated as
a parabolic thickening mechanism. The interface has
been found to be rich in the reactive metal (Ti) content.
The mechanical strength of the brazed joints has
been analyzed using four-point bend tests. The
strength of the brazed joints initially increased and
then decreased with an increase in the hold time at a
fixed temperature. A maximum strength of 196 MPa
has been obtained for a brazed joint heated at 1,000 C
for 2,700 s containing 2 wt% Ti in the filler alloy. It
was observed that the sample with the maximum
strength had a discontinuous interface
