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Acoustic image left, showing no defects |
The THRU-Scan imaging mode, developed by Sonoscan, uses the ultrasonic transducer above the sample to transmit ultrasound through the whole thickness of the sample. Exiting signals are detected by a sensor located below the sample.
The advantage of THRU-Scan is that it can quickly determine whether a defect exists at any depth within the sample. In this case, the THRU-Scan image revealed three dark features whose boundaries were limited by the die or die paddle. This suggested delaminations at the die attach level, die face and/or the back side paddle. Gating a planar C-SAM image at the die surface level (top image) showed that the delaminations are between the die surface and the mold compound. |
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