kevin kiarash ahi - dmsms 2015

University of Connecticut

A Novel Approach for Enhancement of the

Resolution of Terahertz Measurements for Quality

Control and Counterfeit Detection

Center for Hardware Assurance and Engineering (CHASE)

Electrical and Computer Engineering Department

Kiarash Ahi and Mehdi Anwar

Presented at DMSMS Conference 2015

Phoenix, Arizona

All Rights Reserved 2

Counterfeit component classification

Counterfeit component classification and

comparison of X-ray and THz in detection of

counterfeit components


Detection of recycled blacktopped components

20 21 22 23 24 25 26 27 28 29 300

0.05

0.1

0.15

0.2

0.25

X: 27.77

Y: 0.1394

Time Delay [ps]

Dete

cte

d P

uls

e M

ag

nit

ud

e [

au

]

X: 28.71

Y: 0.06609

X: 23.91

Y: 0.1047

16 17 18 19 20 21 22 23 24 25 26 270

0.05

0.1

0.15

0.2

0.25

0.3

X: 21.56

Y: 0.2727

Dete

cte

d P

uls

e M

ag

nit

ud

e [

au

]

Time Delay [ps]

X: 24.02

Y: 0.1371

X: 22.38

Y: 0.0742

X: 17.11

Y: 0.1235

20 21 22 23 24 25 26 27 28 29 300

0.05

0.1

0.15

0.2

0.25

X: 27.66

Y: 0.1439

Time Delay [ps]D

ete

cte

d P

uls

e M

ag

nit

ud

e [

au

]

X: 28.48

Y: 0.06966

17 18 19 20 21 22 23 24 25 26 270

0.05

0.1

0.15

0.2

0.25

X: 24.02

Y: 0.1644

Time Delay [ps]

Dete

cte

d P

uls

e M

ag

nit

ud

e [

au

]

X: 24.84

Y: 0.06998

Ref

lect

ed F

rom

th

e bla

ck-t

opped

mat

eria

l

(Top figure) Reflection of the THz pulse from the top surface of an

authentic IC;

(Bottom figure) Reflection of the THz pulse from the top surface of a

counterfeit IC.

Ref

lect

ed F

rom

the

ori

gin

al s

urf

ace


Detection of recycled components

40 50 60 70 80 90 1000

0.02

0.04

0.06

0.08Reflected Pulse From a Contaminated Spot on the Surface of a Counterfeir IC

Time Delay [ps]

TH

z S

ign

al

[au

]

(b)

(c)

(a)

40 50 60 70 80 90 1000

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08Reflected Pulse From the Left Side (Not Sanded) of a Counterfeir IC

Time Delay [ps]

TH

z S

ign

al

[au

]

40 50 60 70 80 90 1000

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08Reflected Pulse From the Right Side (Sanded Side) of a Counterfeir IC

Time Delay [ps]

TH

z S

ign

al

[au

]

(a) Reflected THz pulse from the left side of the surface of a counterfeit sanded recycled

IC and vertical image of the IC under an optical microscope (b) Reflected THz pulse

from the right side of surface of a counterfeit sanded recycled IC the and vertical image

IC under an optical microscope; this side is thinner as a result of being sanded. (c) )

Reflected THz pulse from the contaminated spot of a recycled couterfeit IC.

More

del

ay

Dif

fere

nt

refl

ecti

on c

har

acte

rist

ic

Sanded

Contaminated

Normal


Imaging with THz pulsed laser

The stepper motors are mounted to make uniform spot measurements possible in a 2D

plane in order to mak THz images

Y Stage

Stepper Motor X

Sta

ge

Ste

pp

er M

oto

r

Sample

Detector

Transmitter


Detection of recycled components

THz reflection images on the left and optical images using a high resolution microscope on the right. (a)

Images of an authentic IC. (b) Images of a counterfeit recycled IC: the contaminated spot is obvious in

the THz image. This contamination is soldering paste which likely is used by counterfeiters during the

recycling process of the IC from its old circuit board. (c) Image of an IC which is sanded on one side.

The difference of the reflected THz pulse magnitude is obvious in the THz image.

Sanded

Contaminated

Authentic

Variance is

Higher on

the sanded

side! (a simple computer

code gives the

counterfeit IC!)

Contamination

is detected !


Inspection of packaging materials: Detection of

Classes # 3, 4 and 6

Time delay

Attenuation

(a)

(b)

(c)

(a) Three ICs including two authentic and one counterfeit. (b) THz pulses in transmission from

these ICs. (c) Fourier spectrum of these pulses.


Inspection of the die and bond wires: Detection

of Classes # 3 and 5

Two electronic chips one counterfeit and another authentic. THz and X-ray

transmission images of these ICs; the die geometry of the counterfeit IC (left

image) differs from the authentic one (right image).

THz is non-ionizing,

more accessible, faster,

cheaper and it can do

the work of X-ray!

Authentic Counterfeit


Absorption characteristic of THz Beam

Exponential absorption characteristics of THz beam while passing through a

2.3 mm packaged IC is shown on the left. As it is shown in the right figure,

it’s the lower frequencies, roughly speaking sub 1.5 THz that are transmitted

into materials of IC packages and can be used for inspection purposes.


Firs Method of Enhancement :

Enhancement of THz images

Using Peak Fitting (Simple)

The main idea: THz beam is a Gaussian beam and thus

hidden details can be revealed by Gaussian peak fitting!

Enhancement of the Images (Approach-1)


The full vertical image based on conductivity

A code has been developed to convert the detected

THz pulse to the conductivity of each spot of the

object.

The full transmission vertical image The full vertical image based on conductivity


Filtering the IC material, time domain filtering

Here our interest is to inspect the leads outside the IC packaging, so the

delayed signal is filtered out. For inspection of the leads inside the

packaging, the non-delayed signal has to be filtered out.

[m

m]

[mm]


Low Pass Filter to filter the noise


Averaging to decrease the random noise

Making a section by averaging three rows to

decrease the random noise even more


Extracting the locations of the peaks by

Lorentzian

In every 5 pixels we have peaks. Each pixel is equal to 0.24 mm and 5x0.24= 1.2 mm.

Separation between leads are 1.2 mm. So this method leads to distinguishing the leads!

The leads are 0.3 mm wide. So according to Nyquist theory the SPF should be 0.15mm or less, but here the SPF is 1.9mm; which means that we improved the resolution 12.6 times higher than Nyquist limit.


Example of the Applications

The missed bond wires and leads, inside and

outside the packaging of the IC can be detected.

Thus miss produced ICs in QC as well as recycled

counterfeit ICs can be detected.

An authentic IC A recycled counterfeit IC


Second Method of Enhancement:

Enhancement of THz Images

Using our Advanced

Reconstruction Method

Enhancement of the Images (Approach-2)


Results

0

50

100

150

200

250

050100150200250300350

X: 120

Y: 144

Z: 0.04834

X: 161

Y: 163

Z: 0.06585

X: 84

Y: 163

Z: 0.0532

X: 120

Y: 186

Z: 0.04963

Before

After


Results

Before

After

The obtained measurements are as accurate as 0.02 mm !


Results

The obtained measurements of the die of the IC are as

accurate as 0.02 mm !

Before

After


The obtained dimensions after enhancement are

confirmed by high resolution X-ray image


Above: left: X-ray image intensity diagram of bond wires. Right: X-ray image of

bond wires. ( in converted colors so that be consistent with THz images)

Bottom: Left: THz after enhancement. Right: THz before enhancement.

Results

Intensity [A

U]

THz Image Slice

After Enhancement

(Y axis is intensity)

THz Image Slice

Before Enhancement

Inverted X-ray

image of three

leads inside the

IC

The same inverted

X-ray image of

three leads inside

the IC (Y axis is

intensity this time )

Note: Resolution of X-ray is higher by nature and we use X-ray images as reference to prove

the validity of our reconstructed THz images.

[0

.0

5 m

m]

[0.05 mm]

Intensity [A

U]

Intensity [A

U]

[0.05 mm] [0.05 mm]

[0.05 mm]


Results of Quality Metrics

SSIM´ MSE Spatial Accuracy

Original THz

image

136 0.1485 2.2 mm

Reconstructed

THz image

68 0.1078 0.2 mm

Improvement %50 %27.4 10 times higher

The quality of the reconstructed image is also

measured by the structural similarity (SSIM)

index and mean squared error (MSE). For this

purpose the reconstructed THz images of and

the original THz image, are given to MSE and

the SSIM whereas the reference image is

chosen to be the X-ray image.

*Since the images which are given to MSE and SSIM were small, 48×11 pixels, the values for MSE are small and the

values for SSIM are relatively high. Thus we defined SSIM´ to be (1-SSIM) ×104 for scaling the results of SSIM .


References and Detailed Analysis

1. Kiarash Ahi, Mehdi Anwar, “Terahertz techniques for quality

control and counterfeit detection”, Accepted for the next issue of

International Journal of High Speed Electronics and Systems, 2016.

2. Kiarash Ahi, Mehdi Anwar, “Modeling and developing of terahertz

imaging equation and enhancement of the resolution of terahertz

images using deconvolution”, Accepted for Terahertz Physics,

Devices, and Systems X: Advanced Applications in Industry, May,

2016, Baltimore, Maryland, USA.

3. Kiarash Ahi, Mehdi Anwar, “Review of terahertz application for

characterization, inspection and quality control in near-field and far-

field”, Accepted for Terahertz Physics, Devices, and Systems X:

Advanced Applications in Industry, May, 2016, Baltimore, Maryland,

USA.



4. Kiarash Ahi, Mehdi Anwar, “Simulation of terahertz images from X-

ray images: a novel approach for verification of terahertz images and

identification of objects with fine details beyond terahertz resolution”

Accepted for Terahertz Physics, Devices, and Systems X: Advanced

Applications in Industry, May, 2016, Baltimore, Maryland, USA.

5. Kiarash Ahi, Navid Asadizanjani, Sina Shahbazmohamadi, Mark

Tehranipoor, Mehdi Anwar, “Terahertz characterization of electronic

components and comparison of terahertz imaging with x-ray imaging

techniques” Proc. SPIE 9483, Terahertz Physics, Devices, and Systems

IX: Advanced Applications in Industry, 94830K (May 13, 2015).

6. Kiarash Ahi, Navid Asadizanjani, Mark Tehranipoor, Mehdi Anwar,

“Authentication of electronic components by time domain THz

Techniques”, Connecticut Symposium on Microelectronics &

Optoelectronics (CMOC), Bridgeport, CT, April, 2015.



7. Kiarash Ahi, Navid Asadizanjani, Sina Shahbazmohamadi, Mark

Tehranipoor, Mehdi Anwar, “THZ Techniques: A Promising Platform

for Authentication of Electronic Components” , CHASE Conference

on Trustworthy Systems and Supply Chain Assurance, Storrs, CT,

April 8-9, 2015

kevin kiarash ahi - dmsms 2015

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