Dynamic bending analysis of metallized silicon nitride substrate during thermal cycling via digital image correlation

Digital image correlation (DIC) method was employed to analyze the dynamic bending of a metallized Si3N4 substrate in thermal cycles ranging from −40°C to 250°C. The substrate was monitored by DIC over several consecutive cycles, spanning from 0 to 2501. Three DIC measurement intervals, specifically during 999–1001, 1999–2001, and 2499–2501 cycles, were selected to analyze the bending behavior in response to temperature fluctuations. By the scanning acoustic microscope (SAM), the substrate revealed negligible delamination after 1001 cycles, light delamination after 2001 cycles, and serious delamination post‐2501 cycles. The dynamic bending remained unchanged during 999–1001 cycles. A curve with a negative bending was observed during 1999–2001 cycles, with a peak curvature of .024 mm−1 at −40°C; the negative bending intensified with a curvature reaching .050 mm−1 at −40°C during 2499–2501 cycles. The bending curve then decreased during the heating phase and returned to a non‐bent state at elevated temperatures. The bending curve reversed to positive at 250°C during thermal cycles from 2499 to 2501. The bending behavior throughout thermal cycles was discussed in relation to the asymmetric delamination observed on both sides of the substrate, as well as the distribution of delamination.