Voids Through Transmission

Pictured

Time Domain Imaging (TDI)™
Utilizes an echo (amplitude & polarity) arrival ‘time’ as a reference, such as standard A-Scan, B-Scan and C-Mode type images.

Voids Through Transmission

Chip On Board Voids, Through Transmission - Application Note 1021

Voids Through Transmission
Acoustic image of a COB revealing a darker area at the bottom edge which is a void

Sample & Method

This COB (also shown above) was imaged by THRU-Scan at an ultrasonic frequency of 15 MHz. THRU-Scan uses a second transducer positioned below the sample that collects ultrasound that has penetrated the entire thickness of the sample. In this sample, since the device was mounted on a board, ultrasound traveled through both the device and the board for imaging.

Result

The dark area along the bottom edge of the die is the void.