C-SAM and Q-BAM
Plastic BGA - Q-BAM acoustic cross-section - Application Note 2614
Sample & Method
This BGA was first imaged in planar mode by C-SAM (bottom half of image). Along the white line drawn across the planar image, a cross-sectional Q-BAM image was then made (top half of image).
Gating in the planar image was at the interface between the molding compound and the substrate. The vertical white structures in the planar image are delaminations between the molding compound and the substrate.