Evaluation Engineering - 25

Its round-trip time will be
transducer will launch in each
measured in nanoseconds.
of many scans across the device. Echoes will be returned
The returning echo can carry
information about the depth
from interfaces between the
of the interface, the acoustic
mold compound and the inimpedance (density times
ternal features (leads at top
acoustic velocity) of each
right, die face, die attach, and
of the two materials at the
heat sink) as well as from interfaces with air.
interface, and the change-
positive or negative-in
At a single x-y location,
the infor mation in the
acoustic impedance in crossing the interface.
echo is turned into a single
Figure 1: This diagram shows a side view of the TO-247 and the gates set for
The instrument pulsing
pixel in the acoustic image.
each viewing depth.
the ultrasound and producAn interface where a solid
ing the images is an acousmeets an air gap produces
tic micro-imaging tool. The images shown here were made by the highest amplitude echoes, which will be white pixels
C-SAM tools in Nordson SONOSCAN's laboratories.
in the acoustic image, while the interface between two solids, where ref lection amplitude may range from near zero
to around 60%, is some shade of gray. If the pulse is fully
Side View
While scanning horizontally above the TO-247's surface, the trans- attenuated before it can complete its round trip (unlikely in
ducer repeats this routine many thousands of times a second, each a TO-247), there will be no echo and the pixel will be black.
pulse delivering information about interfaces directly below a In an acoustic image using a color map, any other colors can
single x-y location. Figure 1 is the diagrammatic side view of a TO- be used, although structural defects such as delaminations
247. The row of arrows represents the thousands of pulses that the or voids are often shown in red.

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25



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Evaluation Engineering

Table of Contents for the Digital Edition of Evaluation Engineering

Editor's Note: Combining Forces
By the Numbers
Industry Report
Electrical Safety Test: EST instruments provide safe environment to ensure compliance
RF/Microwave Switching: RF/microwave switching adds flexibility to diverse applications
RF/Microwave: Ground penetrating radar offers new sensor modalities for vehicles
Software: Software boosts power applications
Automated Test: Non-destructive analysis of TO-247 structural defects
Tech Focus
Featured Tech
Machine Vision: The blindfolds are coming off for robotics
Evaluation Engineering - 1
Evaluation Engineering - 2
Evaluation Engineering - 3
Evaluation Engineering - By the Numbers
Evaluation Engineering - 5
Evaluation Engineering - Industry Report
Evaluation Engineering - 7
Evaluation Engineering - Electrical Safety Test: EST instruments provide safe environment to ensure compliance
Evaluation Engineering - 9
Evaluation Engineering - 10
Evaluation Engineering - 11
Evaluation Engineering - 12
Evaluation Engineering - 13
Evaluation Engineering - RF/Microwave Switching: RF/microwave switching adds flexibility to diverse applications
Evaluation Engineering - 15
Evaluation Engineering - 16
Evaluation Engineering - 17
Evaluation Engineering - 18
Evaluation Engineering - 19
Evaluation Engineering - RF/Microwave: Ground penetrating radar offers new sensor modalities for vehicles
Evaluation Engineering - 21
Evaluation Engineering - Software: Software boosts power applications
Evaluation Engineering - 23
Evaluation Engineering - Automated Test: Non-destructive analysis of TO-247 structural defects
Evaluation Engineering - 25
Evaluation Engineering - 26
Evaluation Engineering - 27
Evaluation Engineering - Tech Focus
Evaluation Engineering - 29
Evaluation Engineering - Featured Tech
Evaluation Engineering - 31
Evaluation Engineering - 32
Evaluation Engineering - 33
Evaluation Engineering - Machine Vision: The blindfolds are coming off for robotics
Evaluation Engineering - 35
Evaluation Engineering - 36
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