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Secured Miniaturized System-in-Package Contactless and Passive
Authentication Devices Featuring NFC
Conference Paper · August 2016
DOI: 10.1109/DSD.2016.34
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Secured Miniaturized System-in-Package
Contactless and Passive Authentication Devices
featuring NFC
Juergen Schilling, Walther Pachler, Bernhard Roitner, Thomas Ruprechter,
Holger Bock, Gerald Holweg, and Norbert Druml
Infineon Technologies Austria AG, Graz, Austria
{juergen.schilling, walther.pachler, bernhard.roitner-ee, thomas.ruprechter,
holger.bock, gerald.holweg, norbert.druml}@infineon.com
I. I NTRODUCTION
HF-based RFID and NFC systems are widely spread nowadays. They can be found in our everyday lives, in applications
such as payment, transportation and logistics, healthcare, and
access control systems (see also [1]). A particular boost has
been recognized since RFID/NFC reader functionality has
been integrated into a vast amount of smart phones. The basic
principle of such a contactless RFID/NFC system is illustrated
in Fig. 1. The reader device emits an alternating magnetic
field, which is used to power the transponder and to exchange
data with it by means of modulation. The achievable reading
distance of such a contactless and passive system depends on
several factors. One of the most important factors is the size
of the antenna: the larger the antenna, the better the coupling.
NFC
Reader
Device
Transponder
Power Transfer
Data Transfer
RF-Interface
Abstract—RFID/NFC technology is widely spread nowadays
and applications can be found in our everyday life, for example, in
payment, transportation, logistics, healthcare, and access control.
State-of-the-art contactless and passive authentication solutions
implement relatively large coils outside of the chip. Therefore,
the minimum size is in the order of a few square centimeters,
which limits their use for tagging of certain small-sized goods.
On top of that, those miniaturized solutions which are available
today provide only limited security measures.
Here we introduce miniaturized system-in-package contactless
authentication devices. This novel solution integrates Infineon
Technologies’ CIPURSETM move IC, which is a state-of-the-art
security solution featuring an open security standard, into embedded Wafer Level Ball Grid Array (eWLB) packages, together
with HF-antennas, ferrites, as well as discrete elements that
improve HF-coupling characteristics.
The presented devices provide better HF-coupling characteristics than Coil-on-Chip approaches, which also enable verification
of authenticity of tagged products through NFC-enabled smart
phones. Thanks to the miniaturized package sizes of 3x3 mm,
integration into high-priced products, casings, consumable materials, etc., can be achieved in a discreet way. Furthermore,
the integrated CIPURSETM chip enables not only the anticounterfeiting use-case, but also micropayment, ticketing, access
control, and password storage in a secured way. Therefore, this
miniaturized contactless authentication solution will open up
whole new fields of applications.
Index Terms—Security, System-in-Package, eWLB, RFID,
NFC, CIPURSETM
iR(t)
v(t)
C
Shunt
Electr
onics
Fig. 1. Working principle of an RFID-based contactless system. The reader
emits an alternating and modulated magnetic field that powers the transponder
and through which contactless communication is also enabled. Obtained with
changes from [3].
However, the smaller the antenna and the tags are, the higher
is typically the variety of products that can be tagged. If such
transponders are manufactured small enough, then they can
be integrated into various products, casings, or consumable
materials in a discreet way. Since counterfeiting of designer
products is reported as a major issue with a global economic
value of over $ 865bn, as one can see in Table I and in [2], a
simple, small-sized, and secured way to check genuineness
is eligible. Given this motivation, it is of highest interest
to provide small-sized and secured RFID technology, which
can be integrated into products in a very discreet way and
which can be verified in terms of authenticity with commonly
available RFID reader devices. However, to the best of our
knowledge, there is a major gap in industry and in academia
concerning this field of application.
This work addresses the outlined gap and presents a miniaturized, system-in-package, contactless, and passive authenti-
TABLE I
E STIMATED VALUE OF COUNTERFEIT PRODUCTS , ACCORDING TO [2]
Region
Internationally traded
Domestically consumed
Total
2008 [USD bn]
322.5
177.5
500.0
2015 [USD bn]
865.0
470.0
1335.0
cation solution that features NFC and state-of-the-art security
measures. This is achieved by integrating Infineon Technologies’ CIPURSETM move chip, which is a security chip featuring an open security standard, into embedded Wafer Level
Ball Grid Array (eWLB) packages, together with HF-antennas,
ferrites, as well as discrete elements that improve HF-coupling
characteristics. Thus, a system-in-package security solution is
given that enables not only the anti-counterfeiting use-case,
but also micropayment, ticketing, access control, and password
storage.
Summarizing, this paper makes the following contributions:
• It introduces the novel system-in-package contactless
authentication devices.
• It details design and implementation decisions as well as
simulation results.
• It proves the applicability of the fabricated devices by
means of an access control demonstrator.
This paper is structured as follows. Section II gives a
short introduction into the related work covering the topic of
small-sized RFID solutions. In Section III, the design and the
implementation of the miniaturized transponders are presented.
Followed by Section IV which shows the final fabricated
prototypes as well as the demonstrator. Finally, our results are
concluded and some details about our future work are given
in Section V.
II. R ELATED W ORK
Basically, RFID tags consist of the IC itself and the HF
antenna. This antenna can either be directly attached on the
IC die or it is built on some support material like PVC. While
the IC itself is very small (typically in the range of 1 to
2 mm2 ), most of the area is occupied by the antenna and
the support material. The larger the antenna, the better the
HF coupling and thus the reading distances. The most popular
formfactor for RFID tags is ID-1 with a size of 85.60 mm x
53.98 mm, see also [1]. This card format achieves, together
with a typical reader device, communication distances of up
to 10 cm. However, due to its size, it is not suitable for
an integration into small products. Dual interface systems
with a coil-on-module implementation can be fabricated much
smaller than ID-1 cards. They feature, for instance, a contact
based interface on the front and a contactless RFID interface
on the backside. They are often used with booster antennas in
ID-1 format, which builds a dual interface card. In contrast to
conventional ICs with soldered antenna, these modules do not
have a mechanical connection between module and antenna.
Therefore, they are more robust against mechanic stress in the
region of the solder points and are easier to fabricate. The
smallest way of producing an RFID tag is the coil-on-chip
approach, which has the antenna directly placed on the top
of the IC die. These tags are just as big as the IC itself but
consequently the reading distance is very short. Furthermore, it
is very difficult, if not impossible, to add discrete components
in order to improve the HF coupling characteristics. Again,
they are often used in combination with booster antennas,
as shown by the authors in [4]. Apart from HF RFID tags,
there are also small tags using capacitive coupling instead of
inductive coupling. According to the authors in [5], such coilon-chip solutions are typically very small (in the range of
1 mm2 ), metallic environments do not influence the communication, and no adjustment on a single resonant frequency
is needed. However, the reading distance is below 0.5 mm.
In summary, Table II gives a qualitative comparison of the
discussed technologies with the packaging technology used in
the presented solution.
Apart from the mentioned approaches, antennas can also be
manufactured by printing them on a carrier material. In [5],
the authors present a silver inkjet NFC antenna printed on a
ferrite. By employing such a ferrite, the HF characteristics in
metallic environments is improved significantly. However, as
the authors demonstrate in [6], if ferrites are used, a higher
minimum field strength is required to communicate with the
transponder. As another solution, the authors of [7] presented
a low-cost UHF tag which can be used for tagging batteries
and metallic objects.
In addition to these research activities, there are also some
miniaturized RFID tags commercially available. Table III
provides an overview of the most important implementations
(please note that a password protection is not considered as
a security measure). For instance, Maxell offers coil-on-chip
based tags (ME-Y1001 and ME-Y2000 series) with a size of
2.5 mm x 2.5 mm and a communication distance of around
2 mm. This tag is based on a proprietary communication
protocol. For use in metallic environments also a version
with ferrite is available (Metal Compatible Small RFID Tag).
These tags are rather large and thick but provide a longer
communication distances. Murata also offers HF RFID tags
(MAGICSTRAP R ) with a size of 3.2 mm x 3.2 mm and a
reading distance up to 15 mm and smaller UHF-based tags
with a reading distance of 7 mm. A smart phone readable
TABLE III
C OMPARISON OF THE PROPOSED TAGS WITH STATE - OF - THE - ART
TABLE II
C OMPARISON OF THE TECHNOLOGIES SUITED FOR RFID SOLUTIONS
PRODUCTS
Product
Technology
Size
ID-1
Coil-on-Chip
Coil-on-Module
Cap. Coupling
eWLB
-++
o
++
+
Reading
Distance
++
o
-o
Additional
Components
X
X
X
X
X
Size
HF Properties
+
-o
o
++
Maxell CoC
Maxell Mini
Murata
Murata inlay
This
approach
+
o
+
o
+
Reading
Distance
o
+
+
+
o
Metallic
Env.
X
X
X
X
X
Security
--o
o
++
Protocol
proprietary
ISO 15693
ISO 15693
ISO 14443
ISO 14443
•
NFC
•
Power Transfer
•
AUTHENTIC ?
State-of-the-art security features and measures against
security attacks must be included.
The HF coupling properties shall be good enough to enable communication with commonly used smart phones.
The transponders should be cheap and easy to fabricate.
B. Packaging Technology - eWLB
Authentification
Fig. 2. Possible application scenario: anti-counterfeiting application by means
of the CIPURSETM based authentication device. Authenticity of a high-priced
product is verified with a typical smart phone.
tag comes also from Murata. This 8.3 mm x 8.3 mm big
inlay is readable from a distance of up to 25 mm. The ICs
used by Murata come with basic security support, featuring
an originality signature only. This means that the origin of the
IC can be verified using an asymmetric cryptographic scheme.
Therefore, the UID of the IC is signed and stored during
production. Nevertheless, how important it is to integrate
proper security measures into RFID-based solutions is stressed
by Hutter et al. in [8].
Summarizing, even though there are some miniaturized
RFID solutions available, there is a major gap concerning
miniaturized and secured RFID/NFC solutions. Therefore,
this paper provides an innovative contribution to the ongoing
discussion in this important field of research.
III. S YSTEM - IN -PACKAGE C ONTACTLESS
AUTHENTICATION D EVICES
The vision of our concept is depicted in Fig. 2. Miniaturized
system-in-package security devices shall enable tagging of
products (such as medical devices, casings, or consumable
materials) in a discreet way. By using standardized and secured protocols, communication with the transponders will be
enabled through commonly available reader devices. Thanks
to the employed CIPURSETM security technology, various
kinds of use-cases will be enabled, such as anti-counterfeiting,
micropayment, ticketing, access control, and password storage.
As an example, if integrated into a watch, the watch can be
used also as a personal password storage or as a novel type
of electronic key to your home.
The following section describes the involved concepts, technologies, and the overall system-in-package design in detail.
Please note that due to disclosure policies some critical details
are omitted in the following and in the results chapter.
A. Requirements
Based on the described vision, the following requirements
can be derived for the system-in-package contactless authentication devices:
• They must be small (3x3mm) and flat.
• Additional discrete components, such as capacitors, must
be integrateable into the package.
The integration density of modern ICs increases continuously, but the number of required input and output pads
increases at the same time. This so-called interconnect gap
poses a huge challenge for the chip development industry.
However, there are novel packaging technologies, such as the
eWLB technology, that are able to tackle this challenge. In
this work the embedded Wafer Level Ball Grid Array (eWLB)
packaging technology, see also [9], is employed in order
to accomplish the visioned system-in-package solution. The
original purpose of the eWLB technology was to surround
an IC with a mold compound which provides additional area
for the required soldering balls. The pads on the IC and
the soldering balls were then connected via a redistribution
layer (RDL). In the proposed solution, the mold compound
is exploited as antenna carrier and the redistribution layer is
exploited to build the antenna of the RFID/NFC transponder,
as inspired by a work of the authors in [10]. In contrast to the
substrate, which is the base material for the antenna in coilon-chip devices, eWLB’s mold compound as base material
grants much better HF characteristics. In addition, the eWLB
technology enables the integration of discrete components
(such as resistors and capacitors) and ferrites into the package.
This feature is essential and is exploited to improve the HF
coupling characteristics of the proposed secured system-inpackage solution.
C. Security IC - CIPURSETM move
Infineon Technologies’ CIPURSETM move IC, see also [11],
is used as the main security measure within the proposed
transponders. This miniaturized and cost-efficient IC implements the CIPURSETM L profile which is standardized by
the Open Standard for Public Transportation (OSPT) Alliance,
as described in [12]. It communicates through the ISO/IEC
14443 Type A interface (specified in [13]) and supports a 3way mutual authentication scheme to securely authenticate the
tag to the reader and vice versa using AES-128. The integrity
during data exchange is secured with an AES-MAC and APDU
sequence integrity protections. The employed data exchange
protocol provides inherent resistance against DPA (differential
power analysis). Furthermore, attacks are prevented by both
hardware and software countermeasures.
One of the most important features of the CIPURSETM move
IC is the support of various types of secured applications.
It enables not only the anti-counterfeiting use-case, but also
micropayment, ticketing, access control, password storage, and
others. Summarizing, thanks to the CIPURSETM move IC, a
highly integrated, miniaturized, and programmable security
solution is available which can be efficiently integrated into
the presented system-in-package concept.
3 mm
TABLE IV
M ATERIAL PARAMETERS USED FOR 3D SIMULATION OF THE MAGNETIC
eWLB Package
with Ferrit
3 mm
Underpass
for HF Coil
CIPURSE™ IC
Capacitor
FIELD DISTRIBUTION
Material
Ferrite
Silicon
FR4 (Epoxy)
PET
Air
Vacuum
Glass
Gold
Relative
Permittivity
r [1]
12.0
11.9
4.4
3.2
1.0006
1.0
5.5
1.0
Relative
Permeability
µr [1]
1000
1.0
1.0
1.0
1.0000004
1.0
1.0
0.99996
Electrical
Conductivity
σ [ siemens
]
m
0.01
0
0
0
0
0
0
41·106
HF Coil
Fig. 3. Layout of the system-in-package authentication device featuring
the CIPURSETM move IC, a capacitor for HF tuning, HF antenna, and an
underpass for connecting the HF antenna with the IC.
D. System-in-Package Design
Fig. 3 illustrates the design of the proposed system-inpackage contactless authentication devices. In its current design version, a package size of 3x3 mm is targeted. The design
comprises the following six layers (from bottom to top). The
first or the sixth layer implement an optional ferrite, which
is used to improve the HF characteristics in metallic environments. The second layer integrates the CIPURSETM move
security IC as well as all the needed additional discrete
components, such as capacitors and resistors. These additional
discrete components are required to tune the transponder to a
frequency of 13.56 MHz and to improve the HF characteristics
in general. For example, the integration of an increased capacitor value reduces the negative effects (in particular dangerous
supply voltage drops) of executed operations consuming high
amounts of electrical power (such as cryptographic operations). A simulation, which is carried out with the tool Advanced Design System (ADS), evaluating the tuning behavior
Fig. 4. Simulated HF properties of the proposed system-in-package contactless authentication solution. The design is tuned towards 13.56 MHz.
towards a resonance frequency of 13.56 MHz is presented in
Fig. 4. In order to connect the antenna with the IC, a discrete
underpass component is employed. Since the present design
has still considerable amounts of free space available, one may
also integrate micro batteries (for instance, see [14]) in order
to achieve a boosted NFC system that features an increased
communication distance. Layers three and five of the package
are made of the dielectric material. This material enfolds the
important HF antenna in layer number four. The antenna itself
is implemented by exploiting the redistribution layer of the
eWLB packaging technology.
Thanks to this novel combination of a miniaturized package
design of only 3x3 mm and the usage of state-of-the-art
security technologies, an attractive solution for various kinds
of application scenarios is provided. As mentioned earlier, the
proposed transponders are designed to be integrated into or to
(a) Air
(b) Air + ferrite
(c) Glass
(d) Glass + ferrite
(e) Gold
(f) Gold + ferrite
Fig. 5. This figure illustrates the simulation of the magnetic field distribution
dependent on various types of materials.
Fig. 6. 3D electromagnetic field simulation carried out with the ANSYS
HFSS tool.
be mounted on high-priced products that can be made of metal.
Because of this application scenario, detailed 3D simulations
are carried out in order to evaluate the distribution of the
magnetic field on materials typically found in this context.
Fig. 5 illustrates simulations of the transponder in air, glass,
and gold environments (simulation parameters are detailed in
Table IV) performed with ANSYS HFSS, a tool that is based
on finite element analysis. It can be clearly seen that the
distortion of the magnetic field caused by eddy currents on
conductive materials, like gold, can be avoided by the usage
of a ferrite layer (see also further analyses performed by the
authors of [15]). Therefore, a magnetic field is maintained
that is suitable for contactless communication. Non-conductive
materials, such as glass, do not degrade the magnetic field.
Fig. 6 shows a 3D evaluation of the electromagnetic field of
one of the designs in a non-conductive environment.
E. Design Variants
During the development of this work, several design variants
were fabricated and evaluated. In the following, some design
variations are mentioned that can be of interest for applications:
•
•
•
•
•
In order to improve the HF properties, one can integrate
a second layer for the HF antenna coil.
Another possibility for even better HF properties is
achieved by an increased package size of, e.g., 5 x 5 mm.
Since the maximum communication distance correlates
with the root of the antenna dimension, the package
and the antenna size represent effective optimization
parameters.
Changing the coil width has a significant impact on the
achieved gain.
Integration of larger capacitors improves the supply voltage drop behavior, which is a sever issue in passively
powered contactless systems.
Micro batteries integrated into the package may be used
as a boosted NFC approach in order to improve the
communication distance.
Fig. 7. Manufactured system-in-package contactless authentication device.
CIPURSETM move IC, capacitor, antenna, and underpass are integrated into
one eWLB package.
•
If no security is required (which is for certain application
scenarios valid), other RFID/NFC ICs (such as Infineon
Technologies’ My-D family) with a reduced minimum
operating field strength may then be integrated.
IV. R ESULTS
In the following section the manufactured prototypes are
shown and a possible application scenario is demonstrated.
A. Fabricated Prototypes
Fig. 7 depicts one of the manufactured contactless authentication devices which corresponds to the design presented in Fig. 3. Components, such as the capacitor or the
CIPURSETM move IC, can be easily seen due to the thin
dielectric top layer. The ferrite can either be mounted on top
or on bottom of the package, which depends on the application
scenario. Fig. 8 shows the measurement of the resonance
frequency of one of the manufactured devices carried out
Fig. 8. Measurement of the resonance frequency, which equals 13.75 MHz, of
one of the manufactured system-in-package contactless authentication device.
System-in-Package
Contactless
Authentication Device
Reader Device
Secured
Communication
Open
Verify Authenticity
of Key
Open Lock
Relay Board
Fig. 9. Basic concept of the access control demonstrator featuring a mechanical key that is enhanced with the system-in-package contactless authentication
device.
with a network analyzer from Omicron Labs. Accordingly,
a resonance frequency of 13.75 MHz was measured, which
deviates a bit from the simulated and targeted 13.56 MHz due
to component tolerances and manufacturing variabilities.
3x3mm System-in-Package
Contactless Authentication Device
Fig. 10. Simple metallic key, enhanced with the system-in-package contactless
authentication device.
In this work, we introduced the system-in-package contactless authentication devices that represent a miniaturized
and secured solution for the HF-based RFID and NFC application domains. These devices are realized by integrating
Infineon Technologies’ CIPURSETM move security IC, discrete
components, ferrite, and the HF antenna into one single
eWLB package. Thus, forming a novel system-in-package
solution featuring a size of only 3x3 mm and which can
be easily integrated in various products in a very discreet
way. This secured system-in-package solution enables not
only the anti-counterfeiting use-case, but also micropayment,
ticketing, access control, and password storage. Furthermore,
we presented a manufactured prototype and demonstrated the
feasible application of such a security device by means of the
access control use-case.
Our future work concerns the evaluation of additional design
variants that improve the HF properties of the eWLB approach.
Furthermore, boosted NFC solutions tend to be a promising
research field in this particular context.
B. Access Control Demonstrator
In the following, an access control demonstrator is presented
which showcases how such miniaturized security solutions
may be used in the future. The basic concept of this demonstrator is illustrated in Fig. 9. Our system-in-package contactless
authentication device is attached (in this case by glueing)
to a typical mechanical key, as depicted in Fig. 10. The
mechanical lock is enhanced with a small booster antenna that
fits into the lock’s housing. The booster antenna is connected
to a commercial available RFID/NFC reader device which
is connected to a host PC. The front and the back of the
demonstrator’s assembly is shown in Fig. 11. When the user
puts the key into lock, a two-way security verification is
performed. First, the mechanical key has to fit properly into
the lock. Second, a verification of the authenticity of the
CIPURSETM move IC is carried out by the host PC. Only if
both verifications succeed, then the host PC issues a command
to an electrical relay that triggers a lifting magnet ultimately
releasing the lock.
This example demonstrates the versatile applicability of
the proposed and manufactured secured system-in-package
contactless authentication devices.
We would like to thank our colleagues from Infineon Technologies in Regensburg for their valuable support regarding
the eWLB packaging technology.
V. C ONCLUSION
In recent years, RFID- and NFC-based solutions have become omnipresent in our everyday life. They can be found in
applications such as payment, transportation, logistics, healthcare, or access control. Very famous are passive solutions of
check card format. However, their usage is sometimes limited,
in particular, in the fields of anti-counterfeiting and logistics
due to their large and indiscreet HF antennas. There are only
few miniaturized HF-based RFID and NFC solutions available,
and most of them disregard the very important security aspect.
Therefore, there is a gap concerning miniaturized and secured
solutions for the HF-based RFID application domain.
Fig. 11. Frontside and backside of the access control demonstrator showing
the electronics and the lifting magnet responsible for releasing the lock. The
booster antenna is integrated into the lock and thus cannot be seen.
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