Manipulating the interfacial structure is vital to enhancing
the
interfacial thermal conductance (G) in Cu/diamond
composites for promising thermal management applications. An interconnected
interlayer is frequently observed in Cu/diamond composites; however,
the G between Cu and diamond with an interconnected
interlayer has not been addressed so far and thus is attracting extensive
attention in the field. In this study, we designed three kinds of
interlayers between a Cu film and a diamond substrate by magnetron
sputtering coupled with heat treatment, including a W interlayer,
an interconnected W–W2C interlayer, and a W2C interlayer, to comparatively elucidate the relationship
between the interfacial structure and the interfacial thermal conductance.
For the first time, we experimentally measured the G between Cu and diamond with an interconnected interlayer by a time-domain
thermoreflectance technique. The Cu/W–W2C/diamond
structure exhibits an intermediate G value of 25.8
MW/m2 K, higher than the 19.9 MW/m2 K value
for the Cu/W2C/diamond structure and lower than the 29.4
MW/m2 K value for the Cu/W/diamond structure. The molecular
dynamics simulations show that the G of the individual
W2C/diamond interface is much higher than those of the
individual Cu/diamond and W/diamond interfaces and W2C
could reduce the vibrational mismatch between Cu and diamond; however,
the G of the Cu/W2C/diamond structure
is reduced by the lower thermal conductivity of W2C. This
study provides insights into the relationship between the interconnected
interfacial structure and the G between Cu and diamond
and offers guidance for interface design to improve the thermal conductivity
in Cu/diamond composites.
The stability of the thermal properties of diamond/Al composites during thermal cycling is crucial to their thermal management applications. In this study, we realize a well-bonded interface in diamond/Al composites by interfacial in situ Al4C3 engineering. As a result, the excellent stability of thermal conductivity in the diamond/Al composites is presented after 200 thermal cycles from 218 to 423 K. The thermal conductivity is decreased by only 2–5%, mainly in the first 50–100 thermal cycles. The reduction of thermal conductivity is ascribed to the residual plastic strain in the Al matrix after thermal cycling. Significantly, the 272 μm-diamond/Al composite maintains a thermal conductivity over 700 W m−1 K−1 after 200 thermal cycles, much higher than the reported values. The discrete in situ Al4C3 phase strengthens the diamond/Al interface and reduces the thermal stress during thermal cycling, which is responsible for the high thermal conductivity stability in the composites. The diamond/Al composites show a promising prospect for electronic packaging applications.
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