JPH11328036A - Ic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent information stored in the memory of an integrated circuit from being read by a third person. SOLUTION: An integrated circuit 5 including a memory where information is stored is mounted on an IC chip 2, and a processing operation is performed in the integrated circuit 5 by a first battery 3. A capacitor 13 where electric energy to erase information in the memory is stored is connected in parallel to a second battery 4 which erases information in the memory. A voltage detection circuit 14a which turns on a switching transistor 14b connected between the capacitor 13 and the integrated circuit 5 is provided between the first battery 3 and the integrated circuit 5. First and second batteries 3 and 4 are thin film lithium cells, and the second battery 3 and the IC chip 2 are tightly covered with the first battery 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC card having a non-volatile memory in which information readable by encryption or the like is stored.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a conventional IC card.
FIG. 2A is a diagram illustrating a layout of an integrated circuit mounted on an IC card, and FIG. 2B is a cross-sectional view of the IC card. In these figures, 6 is a ferroelectric memory which is a nonvolatile memory, 7 is a read only memory (ROM), 8 is a central processing circuit (CPU), 9 is a volatile random access memory (RAM), These elements 6, 7, 8, 9
Is formed on a silicon substrate to form an IC chip 2. The IC chip 2 is provided with an aluminum electrode 10 for communicating with the outside via electric signals.

In FIG. 1B, reference numeral 30 denotes a base, and a metal pad 31 provided on the base 30 and an IC
The IC chip 2 is fixed on the base 30 by connecting the electrodes 10 of the chip 2 via the gold bumps 32. The IC chip 2 is covered with a protective film 33 formed of a resin such as an epoxy resin or a polyimide, and a space between the protective film 33 and the base 30 is filled with an anisotropic conductive film 34. In this IC chip 2, important information such as a password and cash amount, which are indispensable for security, are stored in the ferroelectric memory 6, and reading and writing of an electric signal from the outside are performed by encryption of the electric signal. To do it. Therefore, since the IC chip 2 is covered by the base 30 and the protective film 33 on the front, rear, top and bottom, unless the cryptographic information is known, the ferroelectric memory 6
It is impossible to read the information stored in the.

[0004]

However, in the above-described conventional IC card, it is not difficult to destroy the protective film 33 mechanically or chemically, but by destroying the protective film 33, There was a risk of reading the information inside.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an IC card in which information stored in a memory of an integrated circuit is prevented from being read by a third party. Is to do.

[0006]

In order to achieve the above object, an IC card according to the present invention comprises: an IC chip on which an integrated circuit including a nonvolatile memory storing information is mounted;
In an IC card including a first battery connected to a part of the IC chip, a second battery for storing electric energy for erasing information stored in the nonvolatile memory; A switch interposed between the battery and the non-volatile memory; and a voltage detection circuit for detecting an abnormality of the first battery and turning on the switch, wherein the first and second batteries are thin-film batteries. At the same time, the first battery is folded in two, and the integrated circuit and the second battery are covered with the first battery in a sealed state.
Therefore, when the first battery is destroyed and the integrated circuit is to be exposed, information detected by the voltage detection circuit and stored in the nonvolatile memory by the electric energy stored by the second battery is erased.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is an exploded perspective view showing an IC card according to the present invention, FIG. 1B is a bottom view in a state where the IC card is similarly assembled, and FIG. 2A is II in FIG.
(A) -II (a) sectional view, and (b) is an equivalent circuit diagram. In these figures, the same or equivalent members as those described in the related art shown in FIG. 9 described above are denoted by the same reference numerals, and detailed description will be appropriately omitted.

In FIG. 1A, an IC card generally designated by reference numeral 1 comprises an IC chip 2 and first and second batteries 3 and 4 as thin-film lithium batteries formed in an elongated rectangular shape. It is configured. Two pairs of electrodes 11a and 11b and electrodes 12a and 12b made of aluminum are formed at both left and right ends of the IC chip 2, and a capacitor 13 and a voltage detection circuit composed of a voltage detection circuit 14a and a switch transistor 14b which will be described later. A part 14 is provided.

The first battery 3 has a positive electrode portion 3a and a negative electrode portion 3b formed on the front and back, respectively, a substantially central portion is folded in two, and one end is folded to form a folded portion 3c. . The second battery 4 has a positive electrode part 4a and a negative electrode part 4b formed on the front and back, respectively, and has one end folded to form a folded part 4c.

Hereinafter, a method of assembling the IC card having such a configuration will be described. First, the negative electrode portion 4b of the second battery 4 is
The second battery 4 is connected to the electrode 12b of the C chip 2 and the positive electrode 4a of the folded portion 4c is connected to the electrode 12a.
On the mounting side). Next, the negative electrode portion 3b of the first battery 3 is connected to the electrode 11b of the IC chip 2 so that the IC chip 2 and the second battery 4 are sandwiched by the folded first battery 3, and the folded portion 3c The positive electrode 3a is connected to the electrode 11a, and the first battery 3 is connected to an IC
The chip 2 and the second battery 4 are fixed in close contact with each other.

In the IC card 1 assembled as described above, as shown in FIG.
The area other than the electrode 10 is the first chip 3
Covered in a sealed state. FIG. 2 (a)
As shown in the figure, the folded first battery 3, the second battery 4, and the IC chip 2 are fixed in a stacked state.
The thickness L1 of the IC card 1 is a value obtained by adding the thickness of the first battery 3, the thickness of the second battery 4, and the thickness of the IC chip 2.

In FIG. 2B, reference numeral 14 denotes a voltage detector, which is a voltage detecting circuit 14a having a function of monitoring the voltage of the first battery 3, and a switch for closing the voltage detecting circuit 14a when the voltage detecting circuit 14a detects an abnormality. And a transistor 14b. That is, the first battery 3 is connected to a part of the IC chip 2 via the voltage detection circuit 14a of the voltage detection unit 14, and the first battery 3 is connected to the first battery 3 by the voltage detection circuit 14a.
Is constantly monitored. The capacitor 13 is connected in parallel with the second battery 4, and the second battery and the capacitor 13 are connected to the integrated circuit 5 via the normally-off (normally off) switching transistor 14 b. Therefore, the switching transistor 14b is normally off, so that electric energy is stored in the capacitor 13. On the other hand, when an abnormality occurs in the first battery 3, the abnormality is detected by the voltage detection circuit 14 a and the switching transistor 14 b is turned on, so the electric energy stored in the capacitor 13 makes use of the ferroelectric memory. The information stored in 6 is erased.

Therefore, in order to observe the element region (pattern surface) of the IC chip 2 for the purpose of unauthorized use,
When the IC chip 2 is to be exposed at the folded portion 3c of the first battery 3, the electrical connection between the positive electrode portion 3a of the first battery 3 and the electrode 11a of the IC chip 2 is cut off.
Therefore, the voltage detection circuit 14a detects this, turns on the switching transistor 14b, and erases the information stored in the ferroelectric memory 6 by the electric energy stored in the capacitor 13. In addition, even when the first battery 3 is simply damaged, the voltage of the first battery 3 drops. Therefore, the voltage detection circuit 14a detects this and stores the voltage in the ferroelectric memory 6. Information is erased. For this reason, the information stored in the ferroelectric memory 6 is protected, so that confidentiality is ensured and the information can be prevented from being falsified. In addition, the first and second batteries 3,
4 and the electrodes 11a, 1 of the IC chip 2
Since the connection with the battery 2a is made via the folded portions 3c and 4c of the batteries 3 and 4, the connection is not visible from the outside. This makes it difficult for a third party to commit fraud and secures confidentiality.

FIGS. 3 and 4 show a second embodiment of the present invention. FIG. 3A is an exploded perspective view showing an IC chip and a second battery, and FIG. FIG. 4A is a bottom view of the IC card, and FIG.
(B) is a sectional view taken along the line IV (b) -IV (b) in (a). The second embodiment differs from the first embodiment in the connection structure between the positive electrode portion 4a of the second battery 4 and the electrode 12a of the IC chip 2. That is, the second battery 4 is formed flat without folding the one end 4c of the second battery 4, and the one end 4c and the electrode 12a of the IC chip 2 are formed into a crank shape in a side view by a thin conductive material. Are connected by the connecting piece 20 formed in the above.
Since the one end 4c of the second battery 4 is not folded back in this way, the thickness L2 of the IC card 1 can be made thinner by approximately one battery 4 than the above-described L1.
Although not shown, an insulating film is formed between the connection piece 20 and the negative electrode portion 3b of the first battery 3.

FIGS. 5 and 6 show a third embodiment of the present invention. FIG. 5A is an exploded perspective view showing an IC chip and a second battery, and FIG. FIG. 6 (a) is a bottom view of the IC card, and FIG.
(B) is a sectional view taken along the line VI (b) -VI (b) in (a). The difference between the third embodiment and the above-described second embodiment lies in the connection structure between the positive electrode portion 3a of the first battery 3 and the electrode 11a of the IC chip 2. That is, the first battery 3 is formed flat without folding back one end 3c of the first battery 3, and one end 3c of the first battery 3 is
The electrode 11a of the C chip 2 is connected by a connecting piece 21 formed in a side view crank shape by a thin conductive material. With this configuration, the IC
The thickness L3 of the card 1 is set to the value L of the second embodiment.
As in the case of No. 2, the battery can be formed to be thinner than L1 by about one sheet of the battery 4.

FIGS. 7 and 8 show a fourth embodiment of the present invention. FIG. 7A is an exploded perspective view showing an IC chip and a second battery, and FIG. FIG. 8 (a) is a bottom view of the IC card, and FIG.
(B) is a sectional view taken along line VIII (b) -VIII (b) in (a). In the fourth embodiment, the nonvolatile memory 6 is a flash memory. When the nonvolatile memory 6 is a flash memory, the voltage required for rewriting is 12 to 15 V. 4 has four layers. That is, three batteries 4 are added to the second battery 4.
1, 42, and 43 are overlapped so as to connect the respective positive and negative electrode portions, and the positive electrode portion 4a of the second battery 4 and I
The electrode 12 a of the C chip 2 is connected via a connection piece 22.

Further, in the fourth embodiment,
The first battery 3 is fixed to the IC chip 2 so as to cover only the integrated circuit mounting side of the IC chip 2 without folding the first battery 3 in two. That is, the second battery 4 and the three batteries 41,
The positive electrode 3a at one end of the first battery 3 is connected to the electrode 11a of the IC chip 2 via the connection piece 23 so as to cover the first and second batteries 42 and 43, and the negative electrode 3b at the other end is connected to the IC.
It is connected to the electrode 11b of the chip 2. The thickness L4 of the IC card 1 according to the fourth embodiment includes the thickness of the IC chip 2, the thickness of four second batteries 4, the thickness of the first battery 3, and the thickness of the connection piece 22. It is the value obtained by adding the thickness.

In the fourth embodiment,
Although three batteries 41, 42, and 43 are superimposed on the second battery 4, only one second battery 4 may be provided if a booster circuit is provided in the integrated circuit 5. In that case, the thickness L4 of the IC card 1 is a value obtained by adding the thickness of the IC chip 2, the thickness of the second battery 4, the thickness of the first battery 3, and the thickness of the connection piece 22. .

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By setting the thickness of the first battery 3 and the second battery 4 to 0.1 mm and the thickness of the IC chip 2 to 0.05 mm, the thickness L1 of the IC card in the first embodiment becomes , 0.45 mm (L1 = 0.1 mm × 4 + 0.
05 mm). In the second embodiment, the thickness of the connection piece 20 is set to 0.01 mm, and an insulating film having a thickness of 0.01 mm is provided between the connection piece 20 and the first battery 3. .37 mm (L2 = 0.1 mm × 3 +
0.05 mm + 0.02 mm). In the third embodiment, L3 is 0.37 mm (L3 = 0.1 m
m × 3 + 0.05 mm + 0.02 mm).

In the first to third embodiments using a ferroelectric memory as the non-volatile memory 6, the voltage required for rewriting is 3 to 5 V, so the voltage of the second battery 4 is 3.0 to 5 V. You may use 3.6V as it is,
Battery 4 in two layers and a voltage of 6.0 to 7.2 V may be used, in which case L1 is 0.55 mm and L
2, L3 becomes 0.47 mm.

In the fourth embodiment, L4 is equal to 0.
57 mm (L4 = 0.1 mm × 5 + 0.05 mm + 0.
02 mm). When the booster circuit is provided and the second battery 4 is made into one sheet, L4 is 0.27 mm.
All of the above-described embodiments fall within the range of the standard value of the thickness of the IC card of 0.76 mm.

Calculating from the amount of electricity required to erase a 1M (mega) bit ferroelectric memory, the capacitor 1
The area of 3 may be about 1 mm ² . The first battery 3 and the second battery 4 are dedicated to security for preventing unauthorized use, and have a limited capacity for operation of the integrated circuit 5. Taking this into consideration, assuming that the capacities of the first battery 3 and the second battery 4 (about 1 mAh / cm ² ), a battery area of 36 to 100 mm ² is sufficient, but any area larger than that is sufficient. Even better. In addition, the first battery 3 and the second battery 4 are not used for the operation of the normal integrated circuit 5, and therefore consume very little. Further, since the capacitor 13 is a MOS type capacitor and the insulating film is a thermal oxide film (SiO ₂ ), the leakage current of the capacitor 13 is extremely small. After the capacitor 13 is charged, the second battery 4 is removed and discharged. As a result of examining the characteristics, it was confirmed that 90% or more of the electric energy of the capacitor 13 was retained even after a lapse of six months.

In this embodiment, the positive electrode portion 3a and the negative electrode portion 3b of the first battery 3 are entirely exposed, but in order to avoid inconvenient conduction,
The surface may be coated with an insulating film if necessary. Further, although the switch 14b closed by the voltage detection circuit 14a is a transistor, the invention is not limited to this. If the switch 14b is formed to be extremely thin,
It may be a mechanical switch. Although the first and second batteries 3 and 4 are lithium batteries, the invention is not limited to this, and other batteries may be used as long as they are thin and foldable.

[0024]

As described above, according to the first aspect of the present invention, the information stored in the memory is protected.
The confidentiality is ensured, and the information is prevented from being falsified.

According to the second aspect of the present invention, the connection between the battery and the electrode of the integrated circuit is covered by the folded portion so as not to be seen, so that the security is more securely maintained.

According to the third aspect of the present invention, an IC
The card can be made thinner.

[Brief description of the drawings]

FIG. 1A is an exploded perspective view showing an IC card according to the present invention, and FIG. 1B is a bottom view in an assembled state.

FIG. 2 (a) is II (a) -II in FIG. 1 (b).
(A) is a sectional view of the line, and (b) is an equivalent circuit diagram of the IC card according to the present invention.

FIG. 3 shows a second embodiment of the present invention.
(A) is an exploded perspective view showing an IC chip and a second battery, and (b) is an exploded perspective view showing the entire IC card.

FIG. 4 shows a second embodiment of the present invention.
(A) is a bottom view of the IC card, and (b) is in (a).
FIG. 4 is a sectional view taken along line IV (b) -IV (b).

FIG. 5 shows a third embodiment of the present invention;
(A) is an exploded perspective view showing an IC chip and a second battery, and (b) is an exploded perspective view showing the entire IC card.

FIG. 6 shows a third embodiment of the present invention,
(A) is a bottom view of the IC card, and (b) is in (a).
FIG. 6 is a sectional view taken along line VI (b) -VI (b).

FIG. 7 shows a third embodiment of the present invention,
(A) is an exploded perspective view showing an IC chip and a second battery, and (b) is an exploded perspective view showing the entire IC card.

FIG. 8 shows a third embodiment of the present invention,
(A) is a bottom view of the IC card, and (b) is in (a).
FIG. 8 is a sectional view taken along line VIII (b) -VIII (b).

9A and 9B show a conventional IC card, and FIG. 9A shows a layout of an integrated circuit mounted on the IC card;
(B) is a sectional view of the IC card.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... IC card, 2 ... IC chip, 3 ... First battery, 3
a, 4a: Positive electrode section, 3b, 4b: Negative electrode section, 4: Second battery, 5: Integrated circuit, 6: Ferroelectric memory, 11a, 11
b, 12a, 12b ... electrodes, 13 ... capacitors, 14 ...
Voltage detecting unit, 14a: voltage detecting circuit, 14b: switching transistor, 20, 21, 22, 23 ... connecting piece.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideyuki Umino 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Masahiko Maeda 3-9-1, Nishishinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Tadao Takeda 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Masaaki Tanno 3-2-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Co., Ltd.

Claims (3)

[Claims] 1. An IC card comprising: an IC chip on which an integrated circuit including a nonvolatile memory storing information is mounted; and a first battery connected to a part of the IC chip. A second battery for storing electrical energy for erasing information stored in the memory;
A switch interposed between the battery and the nonvolatile memory,
A voltage detection circuit for detecting an abnormality of the first battery and turning on the switch, wherein the first and second batteries are thin-film batteries, and the first battery is folded in two. An integrated circuit card, wherein the integrated circuit and the second battery are covered in a sealed state by the battery. 2. The IC card according to claim 1, wherein one ends of the first and second batteries are folded back, and the folded portions are connected to electrodes of an integrated circuit formed on the IC chip. card. 3. The IC card according to claim 1, wherein at least one of the first battery and the second battery and an electrode of the integrated circuit are connected via a flaky connection piece. IC card.