JP3480675B2 - IC card - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC card provided with a non-volatile memory in which readable information such as cryptographic information is stored, and more particularly to an IC card having excellent physical security.

[0002]

2. Description of the Related Art Conventionally, IC cards for electronic cash have been actively developed, but from the viewpoint of security, sufficient measures have not been taken yet.

FIG. 11 shows an example of a conventional IC card,
(A) is a cross-sectional view of an IC card, and (b) is a diagram showing a layout of an integrated circuit mounted on the IC card. In the figure, 1 is a non-volatile memory (flash memory,
Alternatively, a ferroelectric memory, 2 is a read-only memory (R
OM), 3 is a central processing circuit (CPU), 4 is a volatile random access memory (RAM), and these elements 1,
The integrated circuit 5 formed by 2, 3, 4 is mounted on the silicon substrate 10 to form the IC chip 11. Further, on the IC chip 11, an aluminum electrode 12 for communicating with the outside through an electric signal is formed. Reference numeral 13 is a base, and the metal pad 14 and the electrode 12 of the IC chip 11 provided on the base 13 are the gold bumps 1.
The IC chip 11 is fixed on the base body 13 by being electrically connected via 5. Then, the IC chip 11 is covered with a protective film 16 formed of a synthetic resin such as epoxy resin or polyimide, and an anisotropic conductive film (An) is provided in a sealed space surrounded by the protective film 16 and the base 13.
Isotropic Conductive Film (ACF) 17 is filled.

In this way, the IC chip 11 of the IC card
The front, rear, left and right are covered by the base body 13 and the protective film 16 so that they cannot be easily taken out. This IC
In the chip 11, the non-volatile memory 1 stores important information such as a password essential for security and the amount of cash.
The cryptographic technology of the electric signal is used for reading and writing the electric signal from the outside. Therefore, it is virtually impossible to read the information stored in the nonvolatile memory 1 unless the cryptographic information is known.

[0005]

However, in the above-mentioned conventional IC card, it is difficult to mechanically, physically or chemically destroy the protective film 16 for the purpose of illegal use such as falsification of the amount. However, the information in the non-volatile memory 1 may be read by being destroyed.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to prevent information stored in the memory of an integrated circuit from being read by a third party. The purpose is to provide an IC card with excellent physical security.

[0007]

In order to achieve the above object, a first invention is a non-volatile memory (1) in which information is stored.
An integrated circuit (5) including a first electrode (24, 25) and a second electrode
An IC chip having electrodes (26, 27) (11), said IC Ji
The first electrode connected to the first electrodes (24,25) of the cup (11) .
A thin film battery (21) and a second for storing electric energy for erasing the information stored in the non-volatile memory (1) .
A thin film battery (22), a switch (30) interposed between the second thin film battery (22) and the non-volatile memory (1), and an abnormality of the first thin film battery (21) is detected. A voltage detection circuit (29 ) for turning on the switch (30) , the even number of the second thin film batteries (22) are connected in series on the same plane to arrange the IC. The integrated circuit (5) and the second thin film battery (22) are sealed by being electrically connected to the second electrode (26, 27) of the chip (11) and by the first thin film battery (21) . Cover as
The electrode (121a) on the surface side of the first thin film battery (21).
One side (24) of the first electrode (24, 25) through the foil (35)
It is characterized by being connected . In such a structure, when the first thin film battery is destroyed and the integrated circuit is exposed, the voltage is detected by the voltage detection circuit, and the switch is turned on, whereby the electric energy stored by the second thin film battery is detected. The information stored in the non-volatile memory is erased. Therefore, confidentiality is maintained, making it difficult for unauthorized use by a third party. Further, since the even number of second thin film batteries are arranged on the same plane, the thickness of the IC card can be reduced.

In a second aspect based on the first aspect, the first thin film battery (21) is folded in two to cover the integrated circuit (5) and the second thin film battery (22) in a sealed state. Is characterized by. In such a configuration,
The second thin between folded first thin-film battery (21)
By inserting the membrane battery (22) and the IC chip (11) , they can be wrapped.

A third invention is the integrated circuit (5) according to the first invention, wherein the first thin film battery (21) is two.
The second thin film battery (22) is covered from above and below in a hermetically sealed state. In such a configuration,
A first thin film battery (21) consisting of two sheets and a second thin film battery
Since the integrated circuit (5 ) and (22) may be sandwiched and covered, no bent portion is generated. Therefore, the first thin film battery (2
Stress concentration does not occur in 1) .

In a fourth aspect based on the third aspect, the first thin film battery (21) is formed into a substantially circular shape,
The thin film battery (22) is formed in a fan shape or a semicircular shape , and is arranged by connecting an even number of sheets so as to form a substantially circle on the same plane. In such a structure, since there is no corner portion, stress concentration can be relaxed.

A fifth aspect of the present invention is the first, second, third ,
In any one of 4th invention , 2nd thin film
A capacitor (2 ) that stores the electrical energy of the battery (22)
8) is provided. In such a configuration, the first thin film battery (21) is destroyed and the switch (3
When 0) is turned on, the capacitor (28) erases the information stored in the non-volatile memory (1) with the stored electrical energy.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the drawings. 1 to 5 show a first embodiment of a 1C card according to the present invention, and FIG.
Is a plan view of the card body, (b) is a cross-sectional view, (c) is a front view, FIG. 2 is a view showing the element surface of the IC chip, and FIG. 3 is the IC after the IC chip and the second battery are brought into close contact with each other. FIG. 4 is a perspective view of the chip viewed from the element surface side, FIG. 4 is a perspective view showing the first battery, and FIG. 5 is an equivalent circuit diagram of the IC card. It should be noted that the same or equivalent components as those shown in the section of the prior art are designated by the same reference numerals, and the description thereof will be appropriately omitted.

In FIGS. 1 and 2, reference numeral 20 denotes a card body of an IC card. The card body 20 includes an IC chip 11 and first and second batteries 21 and 22 each made of a thin film lithium battery, and the integrated circuit 5 and the first integrated circuit 5 mounted on the IC chip 11 by the first battery 21. Two
The battery 22 is covered in a sealed state.

On the element surface of the IC chip 11, a nonvolatile memory 1 in which information is stored, a ROM 2, a CPU 3, a R
The integrated circuit 5 composed of AM4 is mounted. In addition, the electrodes 12, 24, 25, 2 made of aluminum
6 and 27 are formed, a capacitor 28 and a voltage detection circuit (comparator) described later.
There is provided a voltage detection unit 31 including 29 and a switching transistor 30 (see FIG. 5). The electrode 12 is an IC
A plurality of chips are formed along the edge of the chip 11 on the side opposite to the integrated circuit 5. Between the electrode 12 and the integrated circuit 5, other electrodes 24, 25 (first electrodes) , electrodes 26, 27
(Second Electrode) , Capacitor 28, and Voltage Detection Circuit 2
9 is located.

The first battery 21 is formed in a thin and elongated rectangular shape as shown in FIG.
a and a negative electrode portion 121b are respectively formed, and the substantially central portion in the longitudinal direction is folded in two to cover a part of the IC chip 11 and the second battery 22 in a hermetically sealed state.

In FIG. 3, the second battery 22 is composed of four thin film lithium batteries 22a to 22d. These thin film lithium batteries 22a to 22d are formed in a rectangular shape having a thickness of about 0.1 mm and the same size.
Two on the left and right on the same plane, and two on the front and back,
The aluminum foils 32 are connected in series. Of the four thin film lithium batteries 22a to 22d, the right adjacent corners of the two right thin film lithium batteries 22a and 22d are
The thin film lithium battery 22a is stacked on the IC chip 11, one terminal of the thin film lithium battery 22a is connected to the electrode 26 (FIG. 2), and one terminal of the thin film lithium battery 22d is connected to the electrode 2
Connected to 7. Therefore, the electrodes 26 and 27 are connected by connecting these thin film lithium batteries 22a to 22d.
Is supplied with a predetermined voltage. In this case, the voltage of the thin film lithium batteries 22a to 22d is 3.0 to 3.5 per sheet.
Since it is V, a voltage of 12 to 14 V is supplied in series with four sheets.

Next, an IC equipped with such a card body
A method of assembling the card will be described. First, the first battery 21 is prepared. The first battery 21 has a size large enough to cover the entire second battery 22, and is folded in half at the center in the longitudinal direction as shown in FIG.
The structure in which the second battery 22 is connected to the C chip 11 is inserted, and the edge portion of the first battery 21 is brought into close contact with the structure to seal the structure to cover the card body 2
Form 0. In this sealed state, the edge portion of the IC chip 11 on which the electrode 12 is formed projects outside the first battery 21. Next, this card body 20
Is assembled in a thin case made of synthetic resin (not shown) with the end portion of the IC chip 11 on which the electrode 12 is formed protruding outside and fixed by a hot melt method or the like. To finish.

In the IC card thus assembled, as shown in FIG. 1B, the second battery 22 and the IC chip 11 (however, the edge of the IC chip 11 where the electrode 12 is formed) are formed. (Excluding parts) are covered in a sealed state by the first battery 21. Therefore, the edge portion of the IC chip 11 where the electrode 12 is formed protrudes to the outside of the first battery 21. The positive electrode portion 121a of the first battery 21 is connected to the electrode 24 via the aluminum foil 35, and the negative electrode portion 121b is connected to the electrode 25.

In FIG. 5, the voltage detecting section 31 is a voltage detecting circuit 2 having a function of monitoring the voltage of the first battery 21.
9 and a switch transistor 30 that closes when the voltage detection circuit 29 detects an abnormality in the first battery 21. The first battery 21 is connected to a part of the IC chip 11 via a voltage detection circuit 29, and is constantly monitored by the voltage detection circuit 29. The second battery 22 and the capacitor 28 are connected in parallel and are normally in the off state (normally off) for the switching transistor 30.
It is connected to the non-volatile memory 1 of the integrated circuit 5 and the CPU 3 via. Therefore, since the switching transistor 30 is normally off, a constant voltage (or electric energy) is stored in the capacitor 28.

In this state, when the first battery 21 is peeled from the IC chip 11 in order to expose the element region (element surface) of the IC chip 11 for the purpose of unauthorized use, the positive electrode portion 121a of the first battery 21 is removed. Since the electrical connection between the electrode 24 and the electrode 24 or the negative electrode portion 121b and the electrode 25 is cut off, the voltage detection circuit 29 immediately detects it and turns on the switch transistor 30 to electrically connect the capacitor 28 and the nonvolatile memory 1. Let As a result, the information stored in the non-volatile memory 1 is erased by the voltage stored in the capacitor 28. Further, even when the first battery 21 is simply damaged, a voltage drop occurs, so the voltage detection circuit 29 senses it and erases the information in the nonvolatile memory 1 by the same operation. Therefore, since the information stored in the non-volatile memory 1 is protected, confidentiality can be surely maintained, information can be prevented from being tampered with, and an IC card with excellent physical security can be realized. Further, since the four thin film lithium batteries 22a to 22d are arranged side by side on the same plane, the IC card itself can be made thin.

Here, when the non-volatile memory 1 is a flash memory, the voltage required for rewriting is 12 to 14V, so the voltage of the second battery 22 is preferably 12 to 14V. Calculated from the amount of electricity required to erase a 1M (mega) bit flash memory, a capacitor 28
The area may be about 1 mm ² . Also, the area of each thin film lithium battery 22a to 22d is about 1 mm ² .
Further, the second battery 22 is used together with the first battery 21 as a dedicated battery for security for preventing unauthorized use, and is not used for normal operation of the integrated circuit 5, so that the consumption is extremely small, Can withstand long-term use.
Further, the leakage current of the capacitor (MOS type capacitor) 28 using the thermal oxide film (SiO ₂ ) as an insulating film is extremely small, and after charging the capacitor 28, the second battery 22
When the discharge characteristics were examined by removing the above, it was confirmed that 90% or more of the electric energy of the capacitor 28 was retained even after half a year had passed.

6 to 8 show a second embodiment of the present invention. FIG. 6 (a) is a plan view of a card body, (b) is a sectional view, (c) is a front view, and FIG. 7 is. A perspective view showing a first battery,
FIG. 8 is an equivalent circuit diagram of the IC card. In the second embodiment, an IC chip 11, a first battery 21 composed of two thin film lithium batteries 21a and 21b, and a second battery 22 composed of four thin film lithium batteries 22a to 22d. The point that the card body 33 is configured by
Different from the above embodiment, the other configurations are exactly the same.

The thin film lithium batteries 21a and 21b are the second
The thin film lithium battery 21a has a positive electrode portion 131a and a negative electrode portion 131b on the front and back surfaces thereof.
And the negative electrode portion 141a and the positive electrode portion 141b are formed on the front and back surfaces of the other thin film lithium battery 21b, respectively. These thin film lithium batteries 21a, 21
b covers the portion of the IC chip 11 excluding the edge portion where the electrode 12 (see FIG. 2) is formed and the entire second battery 22 from above and below in a sealed state. Therefore, I
The edge portion of the C-chip 11 where the electrode 12 is formed projects outside the first electrode 21.

In the card body 33 having such a structure, the negative electrode portion 131b of the thin film lithium battery 21a and the negative electrode portion 141b of the thin film lithium battery 21b are in close contact with each other and electrically connected. Positive electrode side 131a of thin film lithium battery 21a and positive electrode side 141a of thin film lithium battery 21b
Are electrically connected via the aluminum foil 120.
Therefore, the thin film lithium batteries 21a and 21b are connected in parallel. The positive electrode portion 131a of the thin film lithium battery 21a is connected to the electrode 24 (see FIG. 2) via the aluminum foil 35, and the negative electrode portion 131b is connected to the electrode 25 (see FIG. 2).

Even in such a structure, the first battery 2
When an abnormality occurs in No. 1, the voltage detection circuit 29 detects the abnormality and turns on the switching transistor 30 to erase the information stored in the non-volatile memory 1 by the voltage stored in the capacitor 28. Therefore, like the first embodiment described above, the information stored in the non-volatile memory 1 is protected, the confidentiality is secured, and the tampering of the information can be prevented.

Further, in this embodiment, stress concentration in the first battery 21 can be prevented. That is, in the first embodiment shown in FIGS. 1 to 5, the first electrode 21 is folded in two so as to cover the second electrode 22 and a part of the IC chip 11 in a sealed state. Therefore, four thin film lithium batteries 22a-22
This is preferable in that it covers d, but stress is concentrated on the bent portion of the first electrode 21, so care must be taken when mounting. On the other hand, in the present embodiment, the first battery 21 is composed of two thin film lithium batteries 21a and 21b, and the second electrode 22 and the IC chip 1 are formed by these.
Since a part of 1 is covered from above and below in a sealed state, there is no bent portion, and stress concentration can be prevented.

Here, the card body 33 shown in FIG. 6 is substantially rectangular, and the card body 33 is housed in a case and I
As a result of repeating the bending test on this card as C card, it was found that stress tends to be concentrated on the corners. Therefore, it is preferable to disperse the stress by inserting a reinforcing plate or the like at the corner where the stress is concentrated.

As a structure for dispersing the stress, the first battery 21 is composed of two thin film lithium batteries 21a and 21b formed in a circular shape as in the third embodiment shown in FIG. The second battery 22 is composed of four thin film lithium batteries 22a to 22d formed in a fan shape forming a substantially quarter circle, and these thin film lithium batteries 22a to 22d are formed into a substantially circular shape on the same plane. The card body may be formed in a circular shape by arranging them and covering these batteries in a state of being sandwiched between two thin film lithium batteries 21a and 21b from above and below in a sealed state.

With such a circular shape, the stress concentration at the corners is greatly alleviated, so the thin film lithium battery 2
It is possible to reduce inconveniences such as metal fatigue of the electrodes 1a, 21b, 22a to 22d. Further, the structure is simple because no separate member such as a reinforcing plate is required.

When the non-volatile memory 1 is a ferroelectric memory, the voltage required for rewriting is 3 to 5 V, so the thin film lithium battery (3.0 to 3) is used as the second battery 22.
It is not necessary to connect four 3.5V) in series, and two may be used. In this case, as in the fourth embodiment shown in FIG. 10, the first battery 21 is composed of two thin film lithium batteries 21a and 21b formed in a circular shape, and the second battery 22 is formed in a substantially semi-circular shape. The two thin film lithium batteries 22a and 22b may be used.

Here, in the second to fourth embodiments, the aluminum foil 120 is used to electrically connect the two thin film lithium batteries 21a and 21b.
It goes without saying that the thin film lithium batteries 21a and 21b are covered with an insulating film on a part of their surfaces to prevent electrical connection other than predetermined electrical connection. Aluminum foil 1
When 20 is used, the position of electrical connection is easily exposed,
It is a little difficult from the viewpoint of physical security, but IC
From the viewpoint of improving the strength and reliability of the card itself, it has a better aspect.

Further, in the first to fourth embodiments, an example in which a part of the back surface of the IC chip 11 is covered with the first battery 21 is shown, but the entire back surface can be exposed to the outside. Is. In such a structure, the IC chip 1
Since the back surface of No. 1 is exposed, there is some difficulty in physical security, but it is preferable in terms of thinning.

[0033]

[Example] The thickness of the IC chip 11 is 0.05 mm, and the first
The thickness of each of the battery 21 and the second battery 22 of 0.
By setting the thickness of the aluminum foil 32 to be 1 mm and the thickness of the aluminum foil 32 to be 0.01 mm, the total thickness of the card body 20 (thickness of the thickest portion) in the first embodiment is 0.36 mm (=
0.1 mm × 3 + 0.01 mm + 0.05 mm).

In the present embodiment, the positive electrode portion 121a and the negative electrode portion 121b (131a, 131a,
However, in order to avoid inconvenient conduction, the surface may be coated with an insulating film if necessary in order to avoid inconvenient conduction. In addition, the voltage detection circuit 29
Although an example in which a transistor is used as the switch 30 that is closed by is shown, the invention is not limited to this, and a mechanical switch may be used as long as it is formed to have an extremely thin thickness.
Further, although thin film lithium batteries are used as the first and second batteries 21 and 22, the invention is not limited to this, and may be, for example, a thin film battery in which sodium is a conductive ion of the electrolyte. Any battery will do.

[0035]

As described above, according to the IC card of the present invention, the information stored in the memory is protected, so that confidentiality can be surely maintained and the tampering of the information can be prevented and the physical security can be improved. It is possible to provide an excellent IC card. Further, it is possible to realize thinning.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a plan view of a card body, FIG. 1B is a sectional view, and FIG.

FIG. 2 is a diagram showing an element surface of an IC chip.

[Fig. 3] I after the IC chip and the second battery are brought into close contact with each other
It is the perspective view seen from the element side of a C chip.

FIG. 4 is a perspective view showing a first battery.

FIG. 5 is an equivalent circuit diagram of an IC card.

6A and 6B show a second embodiment of the present invention, in which FIG. 6A is a plan view of a card body, FIG. 6B is a sectional view, and FIG.

FIG. 7 is a perspective view showing a first battery.

FIG. 8 is an equivalent circuit diagram of the IC card.

FIG. 9 is a plan view of a card body showing a third embodiment of the present invention.

FIG. 10 is a plan view of a card body showing a fourth embodiment of the present invention.

11A and 11B show a conventional IC card, FIG. 11A is a sectional view of the IC card, and FIG. 11B is a diagram showing a layout of an integrated circuit mounted on an IC chip.

[Explanation of symbols]

1 ... Non-volatile memory (flash memory or ferroelectric memory), 2 ... Read-only memory (ROM), 3 ... Central processing circuit (CPU), 4 ... Volatile random access memory (RAM), 5 ... Integrated circuit, 11 ... IC chip,
10 ... Silicon substrate, 12 ... Electrode, 13 ... Base, 14 ...
Metal pad, 15 ... Gold bump, 16 ... Defensive film, 17 ... Anisotropic conductive film (ACF), 20 ... Card body, 21 ... First
, 21a, 21b ... Thin film lithium battery, 22 ... Second battery, 22a-22d ... Thin film lithium battery, 28 ...
Capacitor, 29 ... Voltage detection circuit, 30 ... Switch transistor, 31 ... Voltage detection unit, 33 ... Card body.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tadao Takeda 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-5-88986 (JP, A) Kaihei 2-71345 (JP, A) JP-A-11-306309 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G06K 19/077 G06K 19/073

Claims (5)

(57) [Claims] 1. A non-volatile memory (1) in which information is stored.
An integrated circuit (5) including a first electrode (24, 2)
5), an IC chip (11) having second electrodes (26, 27), and the first electrodes (24, 2) of the IC chip (11).
5) connected to a first thin film battery (21) and a second thin film battery (2) for storing electrical energy for erasing information stored in the non-volatile memory (1).
2), a switch (30) interposed between the second thin film battery (22) and the non-volatile memory (1), and the switch (30) that detects an abnormality of the first thin film battery (21). 30) and a voltage detection circuit (29) for turning on the second thin film battery (22) connected in series on the same plane to arrange the second thin film batteries (22) of the IC chip (11).
Electrically connected to the electrodes (26, 27) of the integrated circuit (5) and the second thin film battery (21).
The thin film battery (22) of (1) is hermetically covered, and the electrode (121a) on the surface side of the first thin film battery (21) is connected to one of the first electrodes (24, 25) through an aluminum foil (35). An IC card characterized by being connected to (24). 2. The IC card according to claim 1, wherein the first thin film battery (21) is folded in two to form an integrated circuit.
An IC card characterized in that (5) and the second thin film battery (22) are covered in a sealed state. 3. The IC card according to claim 1, wherein the first thin film battery (21) has two pieces, and the integrated circuit (5) and the second thin film battery (22) are covered in a sealed state from above and below. The characteristic IC card. 4. The IC card according to claim 3, wherein the first thin film battery (21) is formed into a substantially circular shape, and the second thin film battery (21) is formed into a second thin battery.
An IC card characterized in that the membrane battery (22) is formed in a fan shape or a semicircular shape , and is arranged so as to be connected in series so as to form a substantially circle on the same plane. 5. The IC card according to claim 1, further comprising a capacitor (28) for storing electric energy of the second thin film battery (22). card.