Delamination of Metallized AlN Substrate under Thermal Cycling Test Mornitored by Acoustic Emission and Digital Image Correlation Methods

The metallized aluminum nitride substrate (AlN-AMB) underwent a thermal cycling test with temperatures ranging from
$-40$
to
$250 ^{\circ}\mathrm{C}$
. Cracks and three-dimensional deformation of the sample were monitored by acoustic emission (AE) and digital image correlation (DIC) methods, respectively, throughout successive thermal cycles. Both AE signals and the height of Cu from AlN substrate started to accelerate from the 6
^th
cycle and continued to increase until the eventual failure. The accumulated number of AE hits and the height of Cu delamination from the substrate demonstrated a good correlation. In light of these findings, the delamination of the AlN-AMB substrate was attributed to the accumulation of cracks in the AlN substrate and their interconnected growth.