These 4 plastic BGA packages were imaged simultaneously by the THRU-Scan technique at 15 MHz. THRU-Scan uses a second transducer beneath the sample to collect ultrasound that has traveled through the entire thickness of the sample.
• All four BGA packages have very similar large circular defects. These defects are likely delaminations at the molding compound to substrate level and/or within the substrate. • In three of the packages, there are small areas within the large defect region that are not delaminated. The solder
bumps are visible in these and other areas exhibiting good transmission.• The dark spot near the lower left is the pin one marker. |
