JPH0548057U - IC memory card - Google Patents

Abstract

(57) [Abstract] [Purpose] When mounted on the main unit, static electricity charged on the human body does not discharge to the exposed parts of the device, prevents malfunctions and damages, and is highly reliable. IC memory card. [Structure] An insulating plastic sheet cover panel (4) (4 ') is provided, and the circuit board (1) has a blank portion in a region corresponding to a portion exposed to the outside of the main body device when mounted on the main body device. Pattern circuit (2) only in the remaining area
To form.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an IC memory card which has a significantly improved antistatic characteristic when it is operated in an electronic device.

[0002]

[Prior Art]

 Information such as personal computers, word processors, printers, facsimiles, and other electronic devices (hereinafter referred to as main unit) is temporarily stored, or conversely, SRAM or ROM is used as a medium for supplying prewritten information to the main unit. IC memory cards such as are being used. Typical examples of such IC memory cards are SRAM cards which replace so-called floppy disks in small personal computers and word processors, and ROM cards for condition setting or font data in printers, facsimiles, plotters, etc. Can be mentioned as.

Such an IC memory card is attracting attention as a new medium in the future because it is thinner than the conventional cartridge type and is highly portable, but the main body device is represented by the FCC standard. As well as being subject to various noise resistance standards, the IC memory card that is an accessory of the same is subject to various requirements such as electromagnetic wave resistance (EMI) and electrostatic resistance (ESD). Reliability against external noise is required.

Among them, the reliability against EMI has reached a level where there is no particular problem in practical use, due to the shielding property of the main body device and various measures of the circuit inside the IC memory card or the main body device. Regarding the reliability of ESD, prevention of troubles due to sparks inside the IC memory card due to the inflow of static electricity from the human body is still a major issue for the IC memory card. This phenomenon caused by the inflow of static electricity or electrostatic charge does not always induce a reproducible fault due to the surrounding atmosphere such as temperature and humidity, or the place of inflow of electric charge, etc. The fact that this is a very difficult phenomenon is one of the reasons why this issue has not been fundamentally solved.

FIGS. 4A and 4B are typical examples of the structure of a ROM card as a typical example of a conventional IC memory card. FIG. 4A shows the inside of the IC memory card. Further, FIG. 2B shows the sectional structure at the position of the line CC ′. Although the cover panel 4 is omitted in FIG. 1A, the wiring pattern 2 is formed on almost the entire effective area of the circuit board 1, and the electronic component group 3 such as the memory IC or the logic IC is formed. , Mounted on predetermined pads on the circuit board 1 and electrically connected to each other. Further, the positions of the circuit board 1 and the connector 6 are held by the frame 5, and the whole is covered by the cover panels 4, 4 '. The cover panels 4, 4'are mechanically strong and easy to process. Alternatively, from the viewpoint of measures against electromagnetic noise, conventionally, a metal sheet, which is a typical representative of stainless steel, has been subjected to predetermined printing.

When such an IC memory card is stored as a single unit, it is normally stored in a conductive case, so there is no concern about charging, and when it is mounted on the main unit, the main unit As long as it is completely built in, it will not be touched by the hand during its operation, and no static charge charged to the human body can flow into the IC memory card, so there is no problem. As shown in FIG. 5, when the card body 7 is exposed to the outside when the card body 7 is attached to the body device 8, there is a sufficient possibility that the exposed portion may touch the hand during operation.

In this case, as schematically shown in FIGS. 5A and 5B, the electrostatic charge 9 charged on the human body flows into the cover panels 4 to 4 ′ from the contact point with the hand. .. Further, since the cover panels 4 and 4'have conductivity, the inflowing charges are evenly distributed on the planes of the cover panels 4 and 4 ', and the edges, corners of the pattern 2 or the memory IC or logic IC. The accumulated charge, such as the lead part of the IC, sparks toward a place where it is easy to discharge, causing fluctuations in the address and data buses, ground level, or destruction of the IC chip itself.

Normally, the cover panel and the ground level of the IC memory card circuit board are electrically connected via an appropriate resistance value, and the electric charge charged between the cover panels is gradually discharged to the ground level without being discharged all at once. The amount of electric charge charged to the human body, depending on the atmosphere, can sometimes reach several thousand to 10,000 volts in terms of voltage, and this kind of energy is directly stored in the IC memory card. If it suddenly flows in, the malfunction of the memory IC and the destruction of the main body device may be caused. Therefore, improvement is desired.

[0009]

[Problems to be solved by the device]

 The present invention has been made as a result of various studies in view of such drawbacks of the conventional IC memory card, and the purpose thereof is to be mounted on the main body and extremely resistant to static electricity even during its operation. The purpose is to provide an IC memory card with excellent performance.

[0010]

[Means for Solving the Problems]

 That is, the present invention provides a circuit board on which an electronic component group such as a memory IC and a logic IC is mounted, a connector for electrical connection with a main body device, a frame for holding the circuit board and the connector, and the circuit board and the connector. In an IC memory card having a cover panel covering the frame and the frame as a basic component, the cover panel is made of an insulating plastic sheet, and the circuit board is a main body device when the IC memory card is mounted on the main body device. The IC memory card is characterized in that the area corresponding to the portion exposed to the outside is a blank area and the pattern circuit is formed only in the remaining area.

The inventors of the present invention prevent the charge flowing from the human body from being uniformly dispersed in the entire cover panel, and even if the charge is accumulated, it is not discharged on the electronic component group or the pattern circuit connecting them. It has been found that by adopting the structure, it is possible to realize an IC memory card having extremely excellent static resistance.

Hereinafter, the present invention will be described in detail with reference to the drawings. 1 (a) and 1 (b) show the structure of an IC memory card according to the present invention. In the main body of the IC memory card, the area from the connector 6 to the AA 'line is built in the main body device. The rear area represents the area exposed to the outside of the device.

Although the cover panel is omitted in FIG. 1A, the pattern circuit 2 is formed on the circuit board 1, and the electronic component groups 3 such as the memory IC and the logic IC are mounted on the respective pads. The structure itself electrically connected to each other is basically the same as that of the conventional IC memory card shown in FIG. 4 (a), but in the IC memory card of the present invention, As shown in FIG. 1 (a), the first feature is that the pattern circuit, and thus the electronic component group connected to each other, exists only in the area to be built in the main body. Further, FIG. 1B shows the appearance of the IC memory card, and the structure is basically the same as that of the conventional IC memory card, but the IC memory card of the present invention has a panel. The second feature is that the covers 4, 4'are insulating plastic sheets instead of conventional metal sheets.

That is, in implementing the effects of the present invention, the pattern circuit and the electronic component group on the circuit board of the IC memory card, when mounted on the main body device, are present only in the area built in the main body device. The first requirement is that the cover panels on the front and back surfaces of the IC memory card are both plastic sheets having an insulating property.

In the present invention, the IC memory card has the purpose of preventing the warp of the circuit board in the etching process of the circuit board, the reflow process after mounting the electronic parts, and the mechanical strength of the circuit board. For this purpose, as shown in FIGS. 2A and 2B, the solid patterns 10 and 10 ′ are formed on the front surface and the back surface of the area corresponding to the portion exposed to the outside of the main body device at the opposite positions. However, even in this case, in this case as well, these pattern surfaces are electrically insulated from the pattern circuit 2 for connecting electronic parts provided on the connector side, as shown in FIG. 2 (a). It is essential.

The cover panel used in the present invention is excellent in workability and printability, and is excellent in handling of IC memory cards in terms of chemical and physical characteristics, electrical insulation, mechanical strength, and the like. If so, the material is not particularly limited, and for example, resins such as polycarbonate, polyethylene, polyethylene terephthalate, and polyvinyl chloride are suitable. A conductive layer of aluminum, copper, nickel, etc. is formed on the area of the cover panel that faces the circuit board and corresponds to the component mounting area, and is connected to the ground level of the circuit board through an appropriate resistor. When connected, it gives more desirable results.

As shown in FIG. 3A, when the IC memory card according to the present invention is attached to the main body, when the externally exposed portion is touched, the electrostatic charges charged on the human body are covered by the cover panels 4 to 4. However, since the cover panel maintains electrical insulation, electric charges do not disperse in the area where the electronic component group exists, and therefore the electronic component group, the address bus line, and the data Since there is no possibility of discharging to the bus line or ground line, there will be no fluctuations in signal level or ground level even during operation, and further damage to memory ICs, logic ICs, or main body devices. There is nothing to do.

Further, in the case of the IC memory card provided with the solid pattern 10 surface shown in FIG. 2, as shown in FIG. 3B, the energy of the accumulated charges is transferred to the solid pattern surface. Even if it discharges toward the target, this solid pattern surface is electrically insulated from the pattern circuit 2 that connects the electronic component group 3, so it may prompt fluctuations in signal level and ground level. No, no problem at all.

In any case, the electric charges charged on the surfaces of the cover panels 4 and 4 ′ are not discharged all at once toward the circuit board 1 or the electronic component group 3, and further, it takes a long time for the connector side. Even if it may be gradually dispersed on the cover panel, if enough energy is not connected to the electronic component group or the pattern circuit surface to discharge it all at once, and if there is an appropriate electrical resistance between the cover panel and the circuit board. , The electric charges are gradually released to the ground level of the circuit, so there is no risk of malfunction.

Hereinafter, examples and comparative examples of the present invention will be described. (Example 1) Two mask ROM-IC chips each having an outer size of 54 mm, a length of 85.6 mm, and a thickness of 3.0 mm, in which font data has been written in advance and a data length of 16 bits and a total capacity of 512 Kbytes, Also, an IC memory card having one control logic IC mounted on a circuit board patterned only within a range of 40 mm from the connector side was prepared as a sample. The cover panel was attached with a pressure-sensitive adhesive using a polycarbonate having a thickness of 20 μm. When this IC memory card is installed in the main unit, the area within 48 mm from the connector side is built into the main unit, and the ground level of the IC memory card is at the same level as the main unit ground level. Connected.

This IC memory card is attached to the main body device, and in the access state, the reference level is set to be the same as the ground level of the main body device, and a discharge time constant of 150 pF and 100 Ω is used to expose it from the main body. The probe of the tester in which a voltage of +15 KV was applied to the cover panel of the part where the voltage was +15 KV was repeatedly discharged at 15-second intervals for a total of 10 times, and then at a voltage of −15 KV for a total of 10 times, for a total of 20 discharges. During this test, no malfunction of the main unit was found, and the font data was correctly supplied to the main unit.

Example 2 The same IC as in Example 1 except that a solid pattern surface having a width of 45 mm and a length of 32 mm is formed at a position of 52 mm or more from the connector side at a position facing the front and back of the circuit board, respectively. When a memory card was prepared and a discharge test was conducted in the same manner as in Example 1, no malfunction was observed as in Example 1, and normal operation was maintained.

Comparative Example 1 The same IC memory card as in Example 1 was prepared except that a stainless steel plate having a thickness of 150 μm was used as the cover panel, and the same test as in Example 1 was conducted. The main unit malfunctioned when it was discharged three times, and at the fifth time it did not work at all, and the memory IC chip of the IC memory card itself was destroyed.

Comparative Example 2 A comparative example except that the mounting area of the electronic component group such as the memory IC chip and the logic IC chip is 78 mm from the connector side, and the pattern is laid out on almost the entire surface of the circuit board. When the same test as in Example 1 was performed using the same IC memory card as in Example 1, not only did the main unit malfunction due to the first discharge with a voltage of + 15KV, but the memory IC chip itself of the IC memory card was completely inaccessible. Became.

[0025]

[Effect of the device]

 According to the present invention, when a part of it is exposed from the main body device, it is inherent in a conventional IC memory card, such as malfunction due to electrostatic noise due to charging, or destruction of the IC memory card or main body. It is possible to realize a highly reliable new IC memory card that overcomes a fatal drawback, and it is necessary to maintain the normal card size in appearance, but it does not require a very large storage capacity, and therefore is installed. Since the number of chips of the memory IC is small, it can be particularly effective in applications in which the mounting area on the circuit board can be sufficiently small, such as font cards and initial condition setting cards.

[Brief description of drawings]

1A and 1B are views showing an example of the structure of an IC memory card according to the present invention, FIG. 1A is a top view with a cover panel removed, and FIG. 1B is an external perspective view.

2A and 2B are views showing another embodiment of the IC memory card according to the present invention, FIG. 2A is a top view with a cover panel removed, and FIG. 2B is a sectional view taken along line BB ′ of FIG. ..

FIG. 3 is a side view showing a state in which an IC memory card according to the present invention is mounted on a main body device, and FIG. 3B shows an example in which a solid pattern is provided.

4A and 4B are views showing an example of the structure of a conventional IC memory card, FIG. 4A is a top view with a cover panel removed, and FIG. 4B is a sectional view taken along line CC ′ of FIG.

5A and 5B are side sectional views showing a state in which a conventional IC memory card is mounted on a main body device, FIG. 5A shows a state in which a rear portion of the card is charged, and FIG. 5B shows a state in which electrostatic charge is spread over the entire card. ..

[Explanation of symbols]

 1 Circuit Board 2 Pattern Circuit 3 Electronic Component Group 4, 4'Cover Panel 6 Connector 7 Card Main Body 8 Main Unit 10 Solid Pattern

Claims (1)

[Scope of utility model registration request] 1. A circuit board on which an electronic component group such as a memory IC and a logic IC is mounted, a connector for electrically connecting to a main body device, a frame for holding the circuit board and the connector, and the circuit board, the connector, and In an IC memory card having a cover panel as a basic component for covering a frame, the cover panel is made of an insulating plastic sheet, and the circuit board is outside the main body device when the IC memory card is attached to the main body device. The IC memory card is characterized in that a region corresponding to a portion exposed to the above is a blank part and a pattern circuit is formed only in the remaining region.