JPH01171897A - Ic card - Google Patents

Abstract

PURPOSE:To provide a protective circuit which is stable irrespective of the value of an abnormal voltage applied to a terminal, by connecting a plurality of signal terminals, which are connected to an IC module, to each other or connecting each of the signal terminals to an earthing terminal, through a varistor. CONSTITUTION:Each of signal terminals 1a-1e of an IC module 7 is connected to an earthing terminal 2 through a varistor 20. When an excessive potential difference is generated between the signal terminals 1a and 1b, the two varistors 20 connected in series with each other through signal conductors 3 and an earthing conductor 4 ensure that a protective circuit is formed through formation of a clipping circuit when the potential difference between the terminals is not lower than two times the operating voltage of the single varistor. Thus, the IC module is prevented from being broken, even when an abnormal voltage of at least several tens of volts is applied between connecting terminals.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an IC card, and particularly relates to an IC card embedded with an IC module having a large storage capacity and arithmetic functions such as a collation function. .

[Conventional technology] An IC module consisting of an IC memory, a CPU, etc. is embedded in a card such as a credit card or an ID card, and is used to provide data mainly related to personal identification, such as a PIN number or ■D code. The intended IC card is being used. The IC card includes a connection terminal for electrically connecting the built-in IC module to an external device. This connection terminal and a 10-module bonding pad buried inside the card are internally connected by a wire or a flexible printed wiring board made of a good electrical conductor such as gold or steel. The above contact M
The terminals are normally exposed, but depending on the way the IC card is carried or stored, the HC terminal may be exposed to unintended abnormal voltage due to high voltage caused by static electricity or contact with exposed charging parts of other electrical circuits. There was a risk that the buried IC module would be destroyed. Also, even if
Even if the end f is covered with metal or dielectric material, voltage is applied to the IC module due to the 89 partial voltage, so there is no change in the risk that a similar phenomenon will occur. To address this issue,
Conventionally, the following measures have been taken. FIG. 8 shows, for example, the conventional I
In Figure 0, which is a circuit diagram showing a protection circuit in a C card, (Ia) to (Ie) are signal terminals, (2) is a ground terminal, (3) is a signal line, (4) is a ground line, and (7) is an IC module, and (9) is a resistance element.

Next, the operation will be explained.

For example, from the outside to the signal terminal (Ial and signal terminal (1b))
If an electrostatic load occurs between the signal terminals (1a) and (1b), the resistance element (9) is connected between the signal terminals (1a) and (1b) via the signal line (3) and the ground line (4). This combined resistance disperses the static charge that has flowed into the IC module (7
) is believed to be able to prevent local concentration of static charges on

[Problems to be solved by the invention] Conventional IC cards are configured as described above to protect the IC module, but in the protection method by voltage sharing using resistive elements, the value of the resistive element is fixed. Because
It is difficult to deal with various situations 0 e.g. several thousand V
When static electricity, which is said to reach up to 100%, is applied between the terminals, it is not possible to sufficiently protect the IC module just by sharing the voltage with a resistance element of about IKΩ to IOKΩ.
IC modules have had the problem of causing voltage breakdown. Furthermore, if the resistance element is a chip component,
When an IC card has a large number of connection terminals, a large number of parts must be mounted, which poses a problem in that the JPY manufacturing process becomes complicated.

In addition, if the resistance element is printed with resistance paint, it is difficult to match the resistance value to the target value, and the manufacturing process becomes complicated, such as requiring a cutting process using a laser, etc. There was a problem.

This invention was made to solve the problems mentioned in E. Even if an abnormal voltage of several tens of volts or more is applied between the connecting terminals, it can prevent the IC module from being destroyed, and it can prevent complicated The purpose of the present invention is to obtain an IC card that does not require extensive manufacturing processes.

[Means for Solving the Problems] The IC card according to the present invention includes an IC module, this IC
A ground terminal connected to the C module, a plurality of signal terminals connected to the IC module, a protection circuit that connects the signal terminals or each of the signal terminals and the ground terminal via a varistor, and protects the signal terminals. and the ground terminal are connected to at least one protection circuit.

[Operation] The varistor according to the present invention is an element having non-ohmic characteristics in which the voltage applied between its terminals increases and when a certain operating voltage is reached, the resistance rapidly decreases. Even if a voltage of several thousand volts is applied between the contact terminals using this varistor, the resistance between the terminals will drop significantly due to the non-ohmic characteristics of the varistor, and the voltage between the terminals will cause the varistor to operate. voltage can be reduced to protect the IC module. Here, the goal of the present invention can be achieved by selecting the operating voltage of the varistor within a range that the IC module can sufficiently withstand, usually from several lOv to several 100V.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a configuration diagram showing one embodiment of an IC card according to the present invention. In the figure, (Ia) to (Ie) are signal terminals, (2) is a ground terminal, (3) is a signal line, (4) is a ground line, (7) is a [C module, (lO) is a card base,
(11) is a lid for protecting the internal circuit, and (20) is a varistor, which is made of a material mainly composed of, for example, ZnO and
This is a ZnO varistor made of metal oxide such as O*.

FIG. 2 is a circuit diagram with the lid (!l) removed.

Next, the operation will be explained.

Now, assume that an abnormal voltage is applied from the outside and an excessive potential difference occurs between the signal terminal (1a) and the signal terminal F[lbJ].

Since there are two varistors (20) connected in series between the signal terminal (la) and the signal terminal (1b) via the signal line (3) and the ground line (4), the terminal ( Ia
).

If the potential difference between (1b) is more than twice the operating voltage of the single varistor, a clip circuit is formed between the signal terminal (Ia) and the signal terminal (lb) and constitutes a protection circuit, so abnormal voltage The IC module (7) can be protected from. A similar operation holds true between other terminals, and if a potential difference occurs between the signal terminal (1) and the ground terminal (2), only one varistor is connected, so 1/2 of the above clipped at a voltage of In this way, the contact VCE
Even if an abnormal voltage of several 107 or more is applied between the terminals,
Destruction of the IC module can be prevented.

In addition, in the above embodiment, the insertion location of the varistor (20) is f.
Although it is set between the Ji line (3) and the grounding wire (4), it may also be between the signal terminal (1) and the grounding terminal (2).
As shown in Figure 3, between the signal terminals (I
It may be a) to (Ie).

Furthermore, if a combination of both is used as shown in Fig. 4, the signal terminals (1a) to (lcl and ground terminal (2)
Even if an abnormal voltage is applied between any of the terminals between them, they are connected through one varistor, so a more reliable effect can be expected.

Further, FIG. 5 shows an IC according to still another embodiment of the present invention.
It is a front view showing a cutout of the card part, (21)
is a varistor module mounted on a board. FIG. 6 is a circuit diagram according to this embodiment. By combining a plurality of varistors (20) into modules in this manner, mounting on an IC card is easy and the manufacturing process can be prevented from becoming complicated.

7 is a cross-sectional view showing one embodiment of the varistor module, in which (2a) is the lower electrode, (2b
), (2d) is a thin film whose main component is crystalline zinc oxide (ZnO), and (2C) is a 1M film whose main component is a crystalline or amorphous metal oxide.
s, sb! A thin film mainly composed of o3 etc., (2e) is the upper electrode, (2r) is the varistor module (sealing + fat to protect the varistor module (2I3), (2g) is the substrate to support the varistor module (21) Yes. f4 membrane (2b1
．． (2c1. (2dl is, for example, several thousand
It is formed with the thickness of a person. A thin film mainly composed of metal oxide (2C), a zinc oxide thin film (2b), and (2dl) have a sandwich structure, forming a symmetrical varistor. Lower electrode (2a), thin film (2b) , (2C),
(2d) and the L part electrode (2C) are sequentially formed on the substrate (2g) by dry thin film forming means such as high frequency sputtering.

After this, the varistor module (
2I) is formed. The method and configuration for forming the varistor module (2I) are not limited to this, and other methods and configurations may be used.

[Effects of the Invention] As described above, according to the present invention, an IC module, a ground terminal connected to this IC module, a plurality of signal terminals connected to the IC module, and each of the signal terminals or the signal terminals By providing a protection circuit that connects the ground terminal via a varistor, and connecting each signal terminal and the ground terminal to at least one protection circuit, a stable voltage can be maintained regardless of the value of the abnormal voltage applied to the terminal. It has a protection circuit that operates and can improve reliability.
It has the effect of allowing you to obtain a C card.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an IC card according to an embodiment of the invention, FIG. 2 is a circuit diagram of an IC card according to an embodiment of the invention, and FIG. 3 is an IC card according to another embodiment of the invention. 4 is a circuit diagram of an IC card according to still another embodiment of the present invention, and FIG. 5 is a partially cutaway front view of an IC card according to still another embodiment of the present invention.
6 is a circuit diagram of the IC card shown in FIG. 5, FIG. 7 is a cross-sectional view of the varistor module shown in FIG. 5, and FIG. 8 is a circuit diagram of a conventional IC card. (la) to (le)...signal terminal, (2)...ground terminal, (7)...IC module, (20)...varistor. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (4)

[Claims] (1) Protection by connecting an IC module, a ground terminal connected to this IC module, a plurality of signal terminals connected to the above IC module, and the signal terminals or each of the above signal terminals and the above ground terminal via a varistor. An IC card characterized in that a circuit is provided, and each of the signal terminals and the ground terminal are connected to at least one of the protection circuits. (2) The IC card according to claim 1, wherein the ground terminal and the signal terminal are each connected to each other via one varistor. (3) The IC card according to claim 1 or 2, wherein the wiring connecting the ground terminal and the signal terminal and the varistor are combined by modularization. (4) The IC card according to claim 3, wherein the modular varistor is constructed by laminating thin films by dry thin film forming means.