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Terahertz Characterization of Electronic Components and
Comparison of Terahertz Imaging with X-ray Imaging Techniques
Kiarash Ahi, Navid Asadizanjani, Sina Shahbazmohamadi, Mark Tehranipoor and Mehdi Anwar
Department of Electrical and Computer Engineering
University of Connecticut
371 Fairfield Way, Storrs, CT 06269, United States
ABSTRACT
THz radiation is capable of penetrating most of nonmetallic materials and allows THz spectroscopy to be used to image
the interior structures and constituent materials of wide variety of objects including Integrated circuits (ICs). The fact
that many materials in THz spectral region have unique spectral fingerprints provides an authentication platform to
distinguish between authentic and counterfeit electronic components. Counterfeit and authentic ICs are investigated
using a high-speed terahertz spectrometer with laser pulse duration of 90 fs and repetition rate of 250 MHz with spectral
range up to 3 THz. Time delays, refractive indices and absorption characteristics are extracted to distinguish between
authentic and counterfeit parts. Spot measurements are used to develop THz imaging techniques. In this work it was
observed that the packaging of counterfeit ICs, compared to their authentic counterparts, are not made from
homogeneous materials. Moreover, THz techniques were used to observe different layers of the electronic components
to inspect die and lead geometries. Considerable differences between the geometries of the dies/leads of the counterfeit
ICs and their authentic counterparts were observed. Observing the different layers made it possible to distinguish
blacktopped counterfeit ICs precisely. According to the best knowledge of authors the reported THz inspection
techniques in this paper are reported for the first time for authentication of electronic components.
Wide varieties of techniques such as X-ray tomography, scanning electron microscopy (SEM), Energy Dispersive X-ray
Spectroscopy (EDS) and optical inspections using a high resolution microscope have also been being employed for
detection of counterfeit ICs. In this paper, the achieved data from THz material inspections/ THz imaging are compared
to the obtained results from other techniques to show excellent correlation. Compared to other techniques, THz
inspection techniques have the privilege to be nondestructive, nonhazardous, less human dependent and fast.
Keywords: THz imaging, THz time domain spectroscopy, THz-TDS, THz tomography, X-ray imaging, physical
inspection, authentication, counterfeit detection
1. INTRODUCTION
THz region of electromagnetic spectrum is defined between 300 GHz to 10 THz, and lies in the gap between electronic
and optical signal generation schemes or in other words between microwave and infrared. Many materials in THz
spectral region have unique spectral fingerprints, consequently, THz techniques can be used for determining the
materials in wide variety of objects from medicines to electronic components 1. THz able penetrates many
nonconductive materials and thus it provides a very promising tool for inspection purposes. Consequently, one of the
most promising applications for THz can be considered as material inspection in general and characterizing electronic
components in particular. THz techniques have several advantages over other inspection and characterization techniques.
THz radiation is non-ionizing and thus not only safer for human in compare to ionizing techniques like X-ray or gamma
inspections but also nondestructive for electronic components. In general, compared to other techniques, THz inspection
techniques have the privilege to be nondestructive, nonhazardous, less human dependent and faster.
A current challenge in electronic component market is the identification of counterfeit electronic components.
Counterfeiting and piracy are longstanding problems which are growing in scope and magnitude. They are of great
concern to governments because of (i) the negative impact they have on innovation, (ii) the threat they pose to the
welfare of consumers and (iii) the substantial resources that they channel to criminal networks, organized crime and
other groups that disrupt and corrupt society. They are of concern to business because of the negative impact they have
on (i) sales and licensing, (ii) brand value and firm reputation, and (iii) the ability of firms to benefit from the
breakthroughs they make in developing new products 2. In the world of electronics, the R&D costs for the semiconductor
industry are indeed extremely high, and protection of the IP rights is of utmost importance. In today’s global economy,
electronics components travel around the world before they make it into a cell phone, computer, automotive, military, or
security system. This global market has greatly reduced the cost of electronics, as large foundries and assemblies can
offer lower prices. However, there is another illicit market willing to undercut the competition with equally illicit parts.
If one of these ends up in consumer products, it will likely go undetected. The part may fail prematurely or
unexpectedly, and the manufacturer will simply label the product as a defective unit and likely replace the product under
warranty. However, if these parts end up in critical applications such as defense, aerospace, automotive, or medical, the
results could be catastrophic. This is the market of counterfeits and it is stirring up serious problems in many sectors 3.
Just how big the market is remains a mystery still. A study conducted from 2005 - 2007 reveals that 50% of original
component manufacturers (OCM) and 55% of distributors (authorized and unauthorized) have encountered counterfeit
parts 4. The Electronic Resellers Association International (ERAI) 5 monitors, investigates, and reports issues that are
affecting the global supply chain of electronics. ERAI, in combination with Information Handling Services Inc. (IHS) 6,
has been monitoring and reporting counterfeit component statistics dating back to 2001. They have reported that
counterfeit ICs are impacting $169B electronics systems industry. The steady increase in reported incidents reflects the
need for effective methods of testing parts and maintaining proper records as parts travel through the supply chain.
Without a doubt, counterfeiting of integrated circuits has become a major challenge due to the deficiencies in the
existing test solutions. Towards this goal, THz techniques are to be added to the conventional inspection methods. The
experiments which are reported in this paper prove THz techniques as a promising approach for distinguishing authentic
electronic components from counterfeit ones.
In this paper, high-speed terahertz spectrometer with laser pulse duration of 90 fs and repetition rate of 250 MHz with
measurement frequencies up to 3 THz is used to identify conclusively authentic and counterfeit electronic components.
Time delays, refractive indices and absorption characteristics are extracted. Spot measurements are correlated to THz
imaging of the whole surface of the IC. It is observed that the packaging of counterfeit ICs, as compared to their
authentic counterparts, made from inhomogeneous materials. THz techniques allow the identification of different layers
of the electronic components enabling the die and lead geometries to be inspected; a considerable difference between the
geometries of the dies/leads of the counterfeit ICs and their authentic counterparts are observed. Identification of the
different layers made it possible to distinguish blacktopped counterfeit ICs within a few seconds. All the above
mentioned inspections are nondestructive, not hazardous and fast.
The paper is organized as follows. In Section-II a quick overview on different classes of counterfeit electronic
components are presented along with the ability of the THz techniques for distinguishing of each class. In section-III,
time domain THz techniques are discussed. Different experiments are developed for distinguishing the different classes
of the counterfeit electronic components. Moreover in this section, measurements in broadband THz frequencies for
characterizations of electronic components are discussed. In Section-IV, capabilities of THz systems for producing
tomography images are discussed and used for electronic components characterization/ authentication. Section V
concludes the paper and gives insights for future works.
2. CLASSIFICATION OF COUNTERFEIT ELECTRONIC COMPONENTS
Counterfeit electronic components are classified to 1) unauthorized copies made by the original manufacturer but outside
the transparent contracts. As an example of the aftermath problems made by this counterfeit class, it can be considered
that components with conventional robustness may be introduced as industry/ healthcare level to the market and thus
early failures in industrial/ healthcare plants may cause catastrophic economical and life disasters; 2) off specification,
defective components and the ones that do are not meet the performance standards which should have been put out in
quality control (QC) section but due to errors in QC section or untrustworthy parties in a manufacture, the defective
components have made their way to the market; 3) components with wrong markings or documentation like the
commercial components which may be introduced as the industrial ones for making more profit. The difference between
this class and the first one is the fact that counterfeiters manipulate the marking and documentations of the authentic
components outside a manufacturer to sell them as a more expensive component with higher functionality or reliability
level; 4) the ones that are not produced by the genuine manufacturers. Counterfeiters may have made these ICs with
reverse engineering approaches or just by developing some ICs that make the similar functionalities as the genuine ICs
in normal situations. But early failure and miss-functionalities of these components under different working situations
are expected and these failures can lead to catastrophic industrial and life disasters; 5) previously used components
which are refurbished by unauthorized parties to be sold as new. These components are aged and also the new marks on
them, which are made by the counterfeiters, may refer to another level of their families; early failures are expected for
them. It should be noted that the fourth class, namely unauthorized recycled components, are responsible for the 80% of
reported counterfeit incidents and thus distinguishing them are highly desired 7–10. In this paper, it is showed that THz
techniques are able to distinguish this class very fast and in non-destructive manners. The counterfeit classifications are
shown in a diagram on Figure 1. In this Figure “C#” refers to the number of the classes that were discussed in this
paragraph.
Recently Guin et al. reported a comprehensive classification of the different counterfeit detection techniques that extends
from visual inspection to X-ray imaging 11. X-ray imaging, though more accurate, damages the electronic component by
ionizing beam. Other techniques offering more objective characterization of counterfeit components are expensive and
require a considerable amount of time to complete detection, but they are mostly destructive as it is discussed in the next
section. THz as a counterfeit detection technology offers an alternative to the existing technologies by being
nondestructive, conclusive and fast. The results using THz for authentication of electronic components are reported in
this paper for the first time. It is shown that besides class 1 and class 2 counterfeit components, which basically are not
distinguishable by any of the physical inspection tests, all the other classes are distinguishable by THz techniques.
Counterfeit
electronic
components
Made by the
genuine
manufacturer
Made by a
counterfeiter
manufacturer
Refurbished by
counterfeiters:
Previously used
Figure 1. Classification of counterfeit electronic components; the green ticks indicates classes
which are distinguishable by THz techniques
Defective
components
C2
Unauthorized
copies
C1
Unauthorized
refurbished
C5
Unauthorized
copies
C4
Components with
Wrong Marking
C3
3. CHARACTERIZING ELECTRONIC COMPONENTS BY THZ TECHNIQUES IN TIME
DOMAIN
In time domain where the THz pulse passes through a material, attenuation and the time delay in the received THz pulse
are observed, compared to the detected THz pulse passing thorough air. The speed of light is higher in the vacuum than
in materials. The fraction of the speed of light in the vacuum,
c
, compared to its speed in a material ,
v
, is defined as
refractive index,
n
:
c
nv
(1)
Most of materials have unique refractive indices and absorption coefficients in THz region 12,13. Observing different
refractive indices and absorption coefficients for two electronic components implies that the components are made up of
different materials. This fact can be used for authentication of the electronic components.
a) THz techniques in transmission mode
The attenuation and time delay of the received THz pulse can be used as metrics to distinguish if two objects are made
up of the same materials or not. For this purpose the THz machine is set up in transmission mode. The experiment setup
in this technique is shown in Figure 2. The sample is placed between the transmitter and the receiver and the time delay
and the attenuation of the THz pulse is measured compared to the reference signal, where no sample is placed in between
the transmitter and the receiver. The THz signals for eleven different samples and the reference THz pulse are shown in
the same scale in Figure 3(c).
For the case of authentication of the components, observing different indices and absorption coefficients for the two
claimed authentic electronic components of the same production series, makes the claim invalid. In Figure 3(a) four ICs
are shown, two of them are counterfeit and the other two are authentic. Although there are no physical differences
between these ICs, different time delays, and thus different refractive indices, and absorption coefficients are observed
for the counterfeit components compared to those of the authentic ones. This is illustrated in Figure 3(b) and (c). For the
sake of accuracy this experiment has been done for eight authentic and three counterfeit ICs as shown in Figure 3(c). In
this figure the differences between the time delays and absorption coefficients of the authentic ICs and their counterfeit
counterparts are obvious.
As it is indicated on Figure 3(b) absorption for counterfeit ICs are two times of the authentic ones. The time delays of the
counterfeit ICs differ from the authentic ones by 0.22 ps. As it is shown in Figure 3 (c) the time delay of reference THz
pulse, is 29.30 ps while time delays are 35.39 ps for authentic ICs and 35.61 ps for the counterfeit ones. Also the
amplitude of reference THz pulse is 27.75 au while this value is 0.07 au for the case of the authentic ICs and 0.04 au for
the case of counterfeit ones.
The thicknesses of the ICs are measured with a Vernier scale and no sensible difference between the thicknesses of the
authentic and counterfeit ICs are observed. For the sake of accuracy the measured thicknesses are also confirmed with an
X-ray tomography system as 2.30 millimeter.
THz pulse Transmitter
Receiver of the THz pulse
The sample
Figure 2 The experiment setup for transmission mode
(a)
26 28 30 32 34 36 38 40
-1.7
-1.6
-1.5
-1.4
-1.3
-1.2
-1.1
Time Delay [Pico Seconds]
Detector Current [a.u.]
Authentic #1
Authentic #2
Authentic #3
Authentic #4
Authentic #5
Authentic #6
Authentic #7
Authentic #8
Counterfeit# 1
Counterfeit# 2
Counterfeit# 3
Reference (air)
(c)
Figure 3 (a) Four ICs, two of them are counterfeit and the other two are authentic, (b) Time domain inspection
of the ICs which are shown in (a) for four ICs, (c)
(b)
Equation (2) can be used for calculating the refractive index of the ICs in this experiment setup 14.
1
ct
nT
(2)
Where c is the velocity of light,
t
is the measured time delay and
T
is the thickness.
By using Equation (3) the attenuation coefficient in units of dB/cm can be calculated 15.
10
20(log ) 8.7
eaa
(3)
Where
a
is called the amplitude attenuation factor and has units in cm-1 and can be calculated by
0
1ln z
aA
zA
(4)
Where
0
A
is the reference, non-attenuated amplitude of the traveling wave and
z
A
is the actual amplitude of the traveling
wave and it is dependent on the z position of the wave and z is the axis from transmitter to the receiver. Consequently,
the amplitude decay can be modeled as equation (5) and thus z can be substituted by the thickness of the IC.
0az
z
A A e
(5)
Substituting the measured values into Equations (2) and Equations (3) gives the refractive index and attenuation
coefficient, for the authentic ICs at 1 THz as 1.79 and 2.263×104 dB/cm respectively. ICs with refractive indices other
than the authentic refractive index can be distinguished as counterfeits. Using Equation (2) and Equations (3), refractive
indices and attenuation coefficients of the counterfeit ICs of Figure 3 are calculated as 1.82 and 2.475×104 dB/cm
respectively. The calculated refractive indices are in the reported range of refractive indices for ceramics16. This
confirms the validity of the experiment.
b) THz techniques in reflection mode
The different layers of a given component are extracted by using reflection mode THz measurement. The experimental
setup is shown in Figure 4. In the reflection mode, due to the variations in distances from the layers of the sample to the
receiver, the reflected beam arrives at the receiver with variable time delays as seen in Figure 5. In this Figure the two
peaks coincide with the two reflections from the top surface and the interface in between the die and the package
material are observed. This distance can be calculated by Equation (6).
The sample
THz pulse Transmitter
Receiver of the THz pulse
Figure 4 The experimental setup in reflection mode. The red laser spot is used to mark the location of the
THz beam
The sample
Receiver of THz pulse
Transmitter of the THz pulse
( 1)
2
ii
ii
t
dn
(6)
Where
i
d
is the thickness of the layer
i
,
( 1)ii
t
is the time separations expressed as optical delay in mm and
i
n
is the
refractive index of the layer
i
. The refractive index is calculated by Equation (2) using measurements performed in
transmission mode. In this experimental setup the THz pulse is not perpendicularly emitted to the sample, and thus the
angle of reflection should be taken into account as well. Since the wavelength of THz pulse is small with respect to the
spatial extend of the interface, the reflected and transmitted wave directions will obey the laws of geometric optics.
Consequently, if the THz pulse reaches the surface of the sample by the incident angle,
i
, then the actual thickness of
the first layer can be calculated using as
12
11
cos
2t
t
dn
(7)
Where the transmitted angle,
t
, is calculated by
11
2
sin
sin ( )
i
tnn
(8)
In this experiment
45o
i
and thus
23o
t
. Substituting these values into Equation (7) gives the thickness of the
layer between the surface and the die as 766 μm which is in consistence with the results of the thickness measurements
by x-ray tomography.
Counterfeiters sand the surface of the recycled ICs to wipe the previously printed marks and then cover the surface with
a black material and reprint new marks on the ICs. They may blacktop new ICs to sell them as higher grade ICs to gain
more profits. One of the highly useful applications for THz techniques in authentication of the electronic components is
distinguishing blacktopped components. Blacktopped counterfeit electronic components have been discussed in many
Figure 5 The transmitted THz pulse in reflection mode experiment setup are received by the
detector with different time delays; X-ray image of the IC from the side and relating the
detected peaks in THz to the different layers detected by X-ray is shown as well.
reports 7,9,18–21. Unauthorized recycled components are responsible for the 80% of reported counterfeit incidents and thus
distinguishing these counterfeit components is significantly important 7–10.
Figure 6 depicts the measured THz pulse from a blacktopped IC. In this Figure two reflections with relatively a very
small time separation, compared to the time separation between the die and the surface, are observed. The existence of
the two pulses right after each other implies that a very thin layer is covering the surface of the IC, in other words, the
surface is covered by a blacktopped layer. Using Equation (7) and the refractive index for organic materials from 17 gives
the thickness of the blacktopped layer as 250 μm.
Since the blacktopping materials are transparent to x-ray, x-ray tomography imaging cannot be used for distinguishing
the blacktopped components. Distinguishing the blacktopped components with an optical microscope is possible as
shown in Figure 6(b) but, prior to inspection the surface of the component should usually be exposed solvents, such as
Figure 6 (a) A blacktopped counterfeit IC, (b) Observing the blacktopped
layer by an optical microscope, (c) The THz pulse`s parts in experiment
setup of Figure 5 observed for a blacktopped counterfeit IC.
(a)
(b)
(c)
acetone. It has been observed that as counterfeiters are using more advanced techniques, the blacktopped materials may
not be soluble in acetone and thus variety of different chemical agents with extended exposure time up to hours and
heated exposures are needed for distinguishing the blacktopped components. Also it is reported that in some cases even
after 7 days of exposing a blacktopped IC to pure acetone, the blacktopped materials were not detectable and the only
way to distinguish the blacktopped layer was making scratches on the surfaces of the ICs with an X-acto knife 18,19.
Obviously, unlike THz techniques, all these methods are destructive, highly time consuming and human dependent thus
expensive and not accurate.
Fourier Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDS) can be used to
distinguish the difference between the materials embedded in the electronic components. Thus, seeing different materials
on the top and sides of a component makes it distinguished as a blacktopped component19. Still, these methods are more
time consuming than THz technique, needing more analysis by the operator and destructive in case of EDS, since X-ray
is an ionizing radiation 19.
Scanning electron microscopy (SEM) and scanning acoustic microscopy (SAM) are also used for accurate surface
texture inspection of the electronic components. If the back and top surface are different, then the component can be
distinguished as a blacktopped 18,19. These methods, compared to THz technique, are highly time consuming and human
dependent thus expensive and not accurate.
C) Broadband terahertz characterization of the refractive index
Variations of refractive indices of materials in different THz frequencies can give a signature to characterize them 16,17.
In Figure 7 refractive indices of two authentic ICs and their counterfeit one are depicted. Interestingly, the refractive
indices of the authentic ICs are the same in the THz frequency domain while that of the counterfeit one stands out.
In addition to the detection of the counterfeit components, this technique can be used in QC sections of the
manufactures22–24. For this purpose, observing differences between the confirmed THz spectroscopy patterns of the
components and the produced components implies that the materials of the produced components are other than what
they are supposed to be. Consequently, the presence of air bubbles and/ or unwanted impurities can be distinguished.
1.5 2 2.5 3 3.5 4
0.5
1
1.5
2
2.5
Frequency [THz]
Refractive Index
Autentic IC #1
Autentic IC #1
Counterfeit IC #1
Figure 7 refractive indices of two authentic ICs and their counterfeit one in THz
frequency domain.
4. CHARACTERIZING ELECTRONIC COMPONENTS BY THZ IMAGING TECHNIQUES
Figure 8 shows THz images in transmission mode and reflection mode experimental setups these images are built by
accumulating the real time absorption and phase measurements on a two dimensional plane. Then the measured values
are depicting by an appropriate color scales.
a) THz imaging techniques in transmission mode
In Figure 9, THz imaging from the authentic and counterfeit ICs are shown. As seen in this Figure, THz images in
transmission mode are formed similar to X-ray imaging where the images are formed based on the attenuation of the x-
ray beam upon reaching the detector. Metals block the THz pulse and thus the materials which are placed behind the die
and leads cannot be observed. Consequently, where no pulse is detected at the detector, die and leads can be considered
to be located. By considering the THz images in Figure 9, two differences between counterfeit ICs and authentic ones, in
terms of the die and leads geometries are distinguishable. (1) The dies in authentic ICs are placed horizontally while in
the counterfeit ones dies are placed vertically. (2) Leads are denser in the left bottom corner of the authentic ICs and thus
an asymmetry is observed for authentic ICs in THz images. Consequently, counterfeit ICs with different die / lead
geometries are distinguishable with THz imaging technique in transmission mode. X-ray can also be used for this
purpose, but THz is not ionizing and thus it is not destructive for electronic components and it needs less safety
regulations for the operators as well.
Figure 8 (a) THz image of an IC of Figure 4, The left image is obtained in reflection
mode and the right one in transmission mode. (b) Color scale for TH images and the x-
ray image of the IC (c) X-ray and THz images are superimposed.
(a)
(b)
(c)
b) THz imaging techniques in reflection mode
The experiment setup in reflection mode is shown in Figure 4. As discussed in section 3-b and shown in Figure 7, the
portions of the THz pulse which are reflected from different layers reaches the detector in different time delays, and thus
obtaining the THz images of different layers of the electronic components is possible. A tomogram is an image of a
plane or slice within an object 15. In Figure 10 images of the different layers of an IC obtained by THz techniques are
shown. According to the definition of tomogram, images in Figure 10 can be called tomograms.
Inspection of die and leads geometries can be considered as applications of this technique. Moreover, inspection of the
surface of the IC can be done using this technique. Figure 11 depicts THz images from the surfaces of a counterfeit IC
and its authentic counterpart. It is observed that the packaging of counterfeit ICs are not made from homogeneous
materials. In Figure 11 (b) existences of foreign materials, with different reflection characteristics, are obvious on the left
top part of the counterfeit IC. Also the image of the whole surface of the counterfeit IC is not as smooth as that of the
authentic one. In particular, it is observed that the variance of the reflected THz from the surface of the counterfeit IC is
2.70 au while that of the authentic one is 1.17 au which is less than 45% of that of the counterfeit IC. Also, the difference
between the peak and the minimum value of the surface is 0.076 au for the counterfeit IC while it is 0.061 au for the
Figure 9 (a) THz image of one of the authentic ICs of Figure 3(a) and its x-ray counterpart. (b) THz image
of one of the counterfeit ICs of Figure 3(a) and its X-ray counterpart. (c) Color scale for the THz images.
Asymmetry
(b)
(a)
(c)
Vertical die
Asymmetry
Horizontal die
authentic IC, in other words the difference between the peak and the minimum value of the surface of the counterfeit IC
is 25% higher than that of the authentic one.
Figure 10 (a) THz image of the surface of one of the ICs of Figure 3(a) in reflection mode.
(b) THz image of the die of the IC. (c) THz image of the leads of the IC, obtained in
reflection mode. (d) The color scale.
(a)
(b)
(c)
(d)
Figure 11 (a) THz image of the surface of one of the authentic ICs of Figure 3(a), (b) THz image of the surface
of one of the counterfeit ICs of Figure 3(a)
(a)
(b)
5. CONCLUSIONS
THz pulse lasers have not been commercially available until only two decades ago and thus THz techniques need to be
developed for different aspects of science and engineering. One of the highly promising fields for THz techniques is
characterization and inspection of electronic components. Other techniques are mostly destructive, time consuming,
hazardous to personnel, human dependent and thus expensive and with higher errors, while THz is nondestructive, fast,
safe for personnel and accurate.
It was also showed that, a wide variety of counterfeit electronic components are also distinguishable with THz
techniques. Due to high benefits, counterfeiters are continually making their counterfeiting techniques more
sophisticated. It becomes more and more difficult to distinguish authentic components from the counterfeit ones. More
and more counterfeit electronic components are injected to the global market as well. Consequently, new authentication
techniques should be developed day by day to distinguish counterfeit components. As discussed in this paper THz
techniques are fast, economically reasonable, reliable, accessible for wide variety of consumers, nonhazardous and
nondestructive. Obtaining the refractive index and absorption coefficient of each of the electronic components by THz
techniques makes it possible to distinguish between the authentic components and their counterfeit counterparts. In this
work different refractive indices and absorption coefficients were observed for counterfeit components compared to their
authentic counterparts. By developing THz techniques distances of the leads and die from the surface of the integrated
circuits (IC) were calculated. The calculated values were confirmed by the results obtained from the X-ray images.
Moreover, blacktopped counterfeit electronic components were distinguished by THz techniques. It is notable that
blacktopped counterfeit components are not distinguishable by X-ray imaging. Moreover, conventional techniques for
distinguishing blacktopped components are time consuming, random, destructive and hazardous for personnel.
Capabilities of THz systems for producing tomography images were also discussed. In this work by THz imaging
techniques, counterfeit ICs with die and lead dislocations were detected. In addition, in THz images from the surfaces of
the ICs presence of foreign materials on the surfaces of the counterfeit components was observed.
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