Multiresolution sparse decomposition for ultrasonic fault diagnosis in advanced packaging

Le résumé fourni par la source

Abstract Quantitative defect evaluation using high-frequency scanning acoustic microscopy remains challenging when echoes from multilayer structures are strongly overlapped. A multiresolution matching pursuit (MRMP) method is proposed for echo separation and defect quantification. The method integrates a physically motivated band-limited echo-atom model and a hierarchical sparse decomposition scheme that combines coarse localization, recursive segmentation, and local dictionary refinement. This strategy improves echo-atom alignment while avoiding the computational cost of a globally dense dictionary. Finite-element simulations and experiments on bonded wafers and flip-chip (FC) package are used to validate the method. The MRMP separates adjacent echo components with a demonstrated axial spacing of 16.86 μm in silicon under the present 1 GSa s −1 sampling condition, corresponding to sub-wavelength spacing. For bonded-wafer signals, the MRMP achieves a signal-to-noise ratio of 18.7 dB and a normalized reconstruction error of 11.52%. For FC solder-bump void evaluation, the estimated void ratio decreases from 35.22% using conventional C-scan and 30.02% using fixed-dictionary orthogonal matching pursuit to 18.75%, close to the x-ray reference of 15.35%. The results show that the MRMP improves echo separability and quantitative reliability for ultrasonic inspection of advanced packaging.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.