JPH0548058U - IC memory card - Google Patents

Abstract

(57) [Summary] [Object] To provide a highly reliable IC memory card by solving the drawback that discharge due to static electricity of the human body causes malfunction or destruction of the IC memory card and the main body device. [Structure] An insulating plastic sheet cover panel (6) (6 ') is provided, and the pattern circuit (2) on the circuit board (3) is at least 5 m from the end face in the peripheral portion of the circuit board.
A blank space of m is provided, and it exists only in the area inside. [Effect] Malfunction and destruction due to static electricity are prevented, and it is particularly effective as a medium for equipment that is strictly regulated by electrostatic noise.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an IC memory card having a significantly improved resistance to static electricity due to charging.

[0002]

[Prior Art]

 Recently, IC memory cards have been actively used as a medium for storing information or providing predetermined information to the main body side. These IC memory cards are normally stored in a conductive case when stored, so there is no obstacle to static electricity noise due to charging. However, when mounted on an actual machine, the human body, especially the part that is touched by the hands, was charged to the human body. Static charge may flow into the IC memory card and cause unexpected damage.

Such a situation is caused by a relatively loose consumer device such as an electronic notebook or a word processor which is subject to noise regulation, and when the IC memory card is completely stored in the device body when mounted in the device body, Although there is almost no problem in cases that are not touched by hand, in cases such as office printers and facsimiles where the so-called electric noise regulations such as FCC standards are strict, such electrostatic resistance is IC. It has become a major issue for memory cards.

FIGS. 3A and 3B and FIGS. 4A and 4B show an example of a structure of a conventional IC memory card, and an electronic component group 1 such as a memory IC and a logic IC The pattern circuits 2 to be connected to each other were mounted on the circuit board 3 formed on almost the entire surface by the etching method or the like. This circuit board was held by a frame 5 together with a connector 4 for making an electrical connection to the outside, and the whole of these was covered on the front and back sides by cover panels 6, 6 '.

The structure shown in FIG. 3 is the most common type in the past, and the cover panel 6 and 6 ′ is made of a stainless sheet from the viewpoint of workability, mechanical strength, electromagnetic wave shielding property, and the like. It was often done. In this case, as shown in FIG. 2B, the peripheral edge of the stainless steel sheet, which is the cover panel, is often bent and assembled so as to reach the outer side surface of the frame 5 in order to enhance the electromagnetic wave shielding property. .

In such an IC memory card, static electricity charged on the human body flows into the IC memory card when a part of the cover panel is touched by hand, but since the cover panel is conductive, Even if the pattern circuit 2 is formed on almost the entire surface of the circuit board 3 or is formed only on a small part of the circuit board 3, the inflowing electric charge is evenly distributed on the cover panel. An electrostatic spark may be generated toward the upper IC chip or pattern circuit, and the ground level or signal level in the IC memory card may fluctuate, or a spark current may flow into the main system, resulting in unexpected failures. there were. That is, in a dry atmosphere, the energy of the electric charge charged to the human body is equivalent to ± 15 KV, and if such energy is concentrated and discharged at one point on the circuit, malfunction of the IC chip or main unit, Had inherent serious drawbacks of destruction.

The structure shown in FIG. 4 is an example of a conventional type improved in view of such drawbacks, and a cover panel uses an insulating plastic sheet instead of a metal sheet typified by stainless steel. ing. In this case, the peripheral edges of the cover panels 6 and 6'cannot be bent as shown in FIG. 3 (b), and a concave portion 7 is provided in a part of the frame 5 as shown in FIG. It was common to fit and fix the cover panels 6, 6'onto.

In such an IC memory card, since the cover panel is insulative, the electrostatic charge flowing from the human body is not evenly distributed over the entire cover panel, and the thickness of the cover panel is large. Although it does not discharge through the direction, the pattern circuit 2 is formed up to the peripheral portion of the circuit board 3 as shown in FIG. 5, so that the interface 8 between the frame 5 and the cover panels 6 to 6'is not charged. When is accumulated, along this interface, it is selectively discharged toward the pattern circuit formed in the peripheral portion of the circuit board. Although the pattern circuit is usually covered with a protective resist, its thickness is as thin as several tens of μm, and discharge by such a high voltage cannot be prevented at all.

For these reasons, even in the IC memory card having the structure shown in FIG. 4, it is unavoidable that the ground level and the signal level fluctuate or the current flows into the main body, as in the case shown in FIG. In any case, an IC memory card having improved reliability against such electrostatic noise has been desired.

[0010]

[Problems to be solved by the device]

 The present invention has been made as a result of various investigations in view of the drawbacks of the conventional IC memory card. The purpose of the present invention is to prevent malfunction and destruction due to inflow of electrostatic charge and to provide a highly reliable IC. It is intended to provide a memory card.

[0011]

[Means for Solving the Problems]

 That is, the present invention provides a circuit board on which an electronic component group mainly composed of a memory IC, a logic IC, etc. is mounted, a connector for electrical connection to the outside, a frame for holding the circuit board and the connector, and the circuit board, In an IC memory card in which a cover panel that covers the connector and the frame is a basic component, and the cover panel is an insulating plastic sheet that is fixed without being placed on the side surface of the frame, the circuit board has a peripheral edge. An IC memory card is characterized in that a blank portion of at least 5 mm or more from the end face is provided in the portion, and the pattern circuit is provided only in the area inside thereof.

Hereinafter, the present invention will be described in detail with reference to the drawings. 1 (a) and 1 (b) show an example of the structure of an IC memory card according to the present invention. In the figure, the patterned circuit 2 is formed only in the inner area of the circuit board 3 except for the blank area of at least 5 mm from the end surface of the peripheral edge portion. Therefore, in the peripheral portion of the circuit board outside this area, there are no electronic parts such as a memory IC and a logic IC, and no circuit pattern exists.

Further, in FIG. 2B, the cover panels 6 and 6 ′ are insulative plastic sheets, but the recess formed in the frame 5 is not indispensable, and as shown in FIG. There is no problem even if it is attached and fixed as it is to a frame having no recess.

When an electrostatic charge flows into the IC memory card according to the present invention, since the cover panel maintains the insulating property, this charge is generated as in the case of the IC memory card having the structure shown in FIG. It will not be distributed over the entire cover panel, and will not penetrate through the cover panel in the thickness direction to cause discharge. When static electricity charged in the human body is made to flow by touching the vicinity of the interface 8 between the frame 5 and the cover panel 6 to 6 ', the interface and the circuit pattern existing at the outermost peripheral edge of the circuit board Since the distance is far enough, no electric discharge along the interface can occur.

The conventional discharge along the interface is a so-called air discharge through the air bubbles in the adhesive and the adhesive at the interface and the air layer in the IC memory card. Normally, the withstand voltage value of air is about 3KV / mm, so if the discharge voltage to the IC memory card is ± 15KV, the pattern circuit will not work even if the path length at the interface is zero. It is necessary to form it only in the inner area separated by at least 5 mm or more, preferably 7 mm or more from the end surface of the circuit board, and it is advantageous to secure this distance on the circuit board. This is the maximum requirement for implementation.

The material of the cover panel used in the present invention is not particularly limited as long as it is an insulating plastic excellent in workability, printability, physical properties, chemical properties or mechanical properties. However, resins such as polyethylene terephthalate, polycarbonate and polyvinyl chloride are suitable materials.

Hereinafter, examples and comparative examples of the present invention will be described.

【Example】

 Example 1 The outer size of the circuit board is 47.5 mm in width and 75.0 mm in length, and the pattern circuit on the circuit board is an inner area excluding a margin portion of 5 mm from the end face provided in the peripheral portion of the circuit board. An IC memory card having a data length of 16 bits and a total capacity of 512K bytes and having font data written therein was prepared. The recess formed in the frame has a width of 1.5 mm, the cover panel is a polycarbonate sheet with a thickness of 150 μm, and a hot-melt type heat-sensitive sheet is used to bond it to the frame at a temperature of 120 ° C. I matched it.

This IC memory card is mounted on a main body device having a common ground level for access, and a probe of a discharge tester having a discharge time constant of 100 Ω and 150 pF, which also has a common ground level, is used for a voltage value of +15 KV. Then, the probe was applied to the interface between the frame and cover panel, and the discharge was repeated 10 times at a rate of once every 10 seconds, and then 10 times at a voltage value of -15 KV, for a total of 20 times. No discharge spark was confirmed, and the main unit operated normally without any abnormality during this test. Moreover, the result was the same even if the discharge was repeated at an arbitrary position on the cover panel.

Example 2 Except that the pattern circuit was present only in the inner area of the circuit board peripheral edge portion excluding the blank area of 10 mm and the charge-up voltage value of the probe of the discharge tester was ± 20 KV. A sample similar to that of Example 1 was prepared and the same test was performed. As a result, no discharge spark could be confirmed, and the main body operated normally without any abnormality.

Comparative Example 1 A sample similar to that of Example 1 was prepared, except that the pattern circuit was present only in the inner region, leaving a 2 mm margin from the end face of the peripheral edge of the circuit board. The test was conducted. As a result, each time the probe was charged up, a spark was found discharging along the interface to the circuit board, and the main unit failed at the third discharge of ± 15 KV, and the IC memory card itself was destroyed, making it inaccessible. became.

[0021]

[Effect of the device]

 The IC memory card according to the present invention is a novel one, which overcomes the drawback of static electricity, which was a conventional weak point. In other words, the IC memory card according to the present invention is a highly reliable medium that does not need to worry about static electricity under the normally considered environment, and is used for OA equipment such as facsimiles and printers with strict electrostatic noise regulations. Especially, it is effective.

[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.

FIG. 2 is an external perspective view showing another embodiment of the IC memory card according to the present invention.

3A and 3B are views showing an example of the structure of a conventional IC memory card, FIG. 3A is a top view with a cover panel removed, and FIG. 3B is a perspective view showing the appearance.

FIG. 4 is a diagram showing another example of the structure of a conventional IC memory card.

FIG. 5 is a side sectional view showing an example of the structure of a conventional IC memory card.

Claims (1)

[Scope of utility model registration request] 1. A circuit board on which an electronic component group composed mainly of a memory IC, a logic IC, etc. is mounted, a connector for electrical connection to the outside, a frame for holding the circuit board and the connector, and the circuit board, In an IC memory card in which a cover panel covering a connector and a frame is a basic constituent element, and the cover panel is an insulating plastic sheet fixed without hanging on the side surface of the frame. At least 5
An IC memory card, characterized in that a margin portion of mm or more is provided and a pattern circuit is provided only in an area inside thereof.