What is a Pulse-Echo and Through Transmission image? Can they be done simultaneous?
Launching ultrasonic energy at the component and analyzing the echoes that return creates the PE (pulse-echo) image. The same transducer is used to send and receive. Since echoes from locations deeper in the component return later, the elapsed time before the return indicates depth. By placing a data gate to select echoes from different depths, the operator can correlate objects in the image to specific depths or layers in the component. For example, a gate can be set to analyze only the echoes from the die attach layer, or between the die and the encapsulant material. The TT (through-transmission) image detects delaminations at any depth in the device rather than at a specific depth set by the gate. For this reason, it is very useful for an overall accept/reject test. However, TT images are typically not as clearly in focus as Pulse-Echo images. Pulse-echo and through transmission can now be done simultaneous. Sonix’s PETT feature increases throughput by generating two images in one p
