JPH1116756A - Signal transmitting/receiving coil and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a signal transmitting/receiving coil which is small in size, high in inductance, and reduced in cost by a method, wherein a spiral conductor is sandwiched between a non-magnetic board and a soft magnetic sheet, and a part of the soft magnetic sheet is filled into the center of the spiral conductor to form the core of a spiral coil. SOLUTION: A non-magnetic board 2 is formed of polyethylene terephtalate, and a spiral conductor 3 of Cu, Ag or the like is formed on the non-magnetic board 2 by plating or the like. Moreover, a terminal 4 of the conductor 3 is connected to another circuit component. Then, a paste composed of soft magnetic power and binder both dispersed into an organic solvent is applied onto the spiral conductor 3 and a coil center 5 and hardened, whereby a soft magnetic sheet 6 provided with a core 7 formed by impregnating the coil center 5 with soft magnetic substance is formed to obtain a signal transmitting/ receiving coil 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type signal transmitting / receiving coil, and more particularly to a coil optimal for an IC card and the like.

[0002]

2. Description of the Related Art In recent years, prepaid cards such as telephone cards have rapidly become widespread, and it is in line with the public opinion that cashless society will increasingly progress in the future. For example, along with the social trends, IC cards and the like, which are high-performance cards, are receiving attention, and some of them have been put into practical use.

[0003] The greatest feature of these IC cards is that they can read and write data, so that, for example, it is possible to relatively easily improve security performance, substitute a bankbook, etc., and use them as electronic money. It is under consideration.

Normally, for example, in an IC card, a microcomputer mounted on the card exchanges data with an external terminal via an external connection terminal. When IC cards are classified according to the data exchange method with the outside, the ISO method,
It can be classified into multi-pin type and non-contact type.

[0005] Among them, the non-contact method is particularly excellent among IC cards, such as security and fewer errors in data processing, as compared with the ISO method and the multi-pin method.
It is expected that it will spread to society with further improvement.

The non-contact method is classified into a method of supplying electric power and inputting / outputting information, and is classified into an optical method, an electromagnetic induction method, a microwave method, and the like.

[0007] Among them, the electromagnetic induction system has a coil mounted on each of an IC card side and a reader / writer side.
When a current flows through the coil on the reader / writer side while the C card is mounted on the reader / writer, a current flows through the coil of the IC card due to electromagnetic induction. It is a method used as.

As the coil for the electromagnetic induction type IC card, an air-core coil in which a conductor such as Cu or Ag is spirally used.

[0009]

However, since this coil is an air-core coil, in order to obtain the required inductance, the number of turns of the coil must be increased, the number of steps is increased, and the manufacturing cost is reduced. There was a drawback that it became high. Increasing the number of turns of the coil increases the cross-sectional area of the coil, which has been an obstacle to miniaturization.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a signal transmitting and receiving coil for a non-contact type electromagnetic induction type IC card which is small in size, has a high inductance, and is low in cost. .

According to the present invention, a conventional air core coil is sandwiched between a non-magnetic substrate and a soft magnetic material, the soft magnetic material is filled in the center of the air core coil to form a core, and a magnetic core is formed in the center. By having a coil having a high inductance coil can be easily obtained, the soft magnetic material, by applying a paste obtained by mixing a soft magnetic powder and a binder into a sheet, An object of the present invention is to provide a small-sized, high-inductance, non-contact electromagnetic induction type signal transmission / reception coil which fills the center of an air-core coil, secures flexibility of a card, and has a high inductance.

[0012]

That is, the present invention relates to a non-contact signal transmitting and receiving coil provided with a spiral conductor, wherein the spiral conductor comprises a non-magnetic substrate and a soft magnetic sheet. Non-contact, characterized in that a part of the soft magnetic material sheet fills a central part of a spiral conductor and forms a core of the spiral coil. Type of signal transmitting and receiving coil.

According to the present invention, the soft magnetic sheet comprises a paste in which a mixture of a soft magnetic powder and a binder is dispersed with an organic solvent, and the paste is applied from above the spiral conductor. A method of manufacturing the above-mentioned non-contact type signal transmitting / receiving coil, characterized by being manufactured by the following method.

The present invention is a non-contact type IC card having the above-mentioned signal transmitting / receiving coil.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is an explanatory diagram of a signal transmitting / receiving coil according to an embodiment of the present invention. 1A is a perspective plan view, and FIG. 1B is a cross-sectional view taken along the line AA in FIG.

In the signal transmitting / receiving coil shown in FIG. 1, the nonmagnetic substrate 2 is made of PET (polyethylene terephthalate).
And Cu, A on the non-magnetic substrate 2 by plating or the like.
The spiral conductor 3 is made of a conductor such as g. In addition,
The terminal 4 at the end of the conductor 3 is connected to another circuit component.

Next, a paste made of a soft magnetic powder and a binder is applied on the spiral conductor 3 and on the coil center portion 5 and cured, so that the coil center portion 5 is impregnated with a soft magnetic material. Thus, the signal transmitting / receiving coil 1 is obtained by forming the soft magnetic material sheet 6 having the core 7.

[0019]

Embodiment A first embodiment of the present invention will now be described with reference to FIG.

(Embodiment 1) First, a PET sheet having a thickness of about 0.2 mm was placed in a standard card size of 54 × 8.
The non-magnetic substrate 2 was cut to 6 mm. Next, a 4-turn spiral conductor 3 having a line width of 0.16 mm and a line thickness of 0.2 mm was formed on the surface by plating. Next, a paste obtained by dispersing a mixture of sendust powder having an average particle size of about 10 μm and a binder at a volume ratio of 1: 1 with an organic solvent was applied to the spiral conductor 3 by a doctor blade method, and The coating and drying were performed on the coil center portion 5 to obtain the signal transmitting and receiving coil 1.

Next, as a comparative example, the same spiral-shaped conductor as above was formed on a PET sheet of the same size.
On top of that, a PET sheet was adhered to produce a signal transmitting / receiving coil having the same shape as in Example 1.

The results obtained by measuring the inductance at 13.56 MHz of the signal transmitting and receiving coils of Example 1 of the present invention and the comparative example with an impedance analyzer and performing comparative evaluation are shown in Table 1.

[0023]

From Table 1, it was found that the inductance value of Example 1 of the present invention was approximately twice as large as that of the comparative example despite the same number of turns of the coil. This is nothing less than the effect of the soft magnetic sheet on the coil.

Next, a second embodiment of the present invention will be described.

Example 2 In the same manner as in Example 1, a 4-turn spiral conductor was formed on a PET sheet. The shape, material, and the like of the coil were manufactured under exactly the same conditions as in Example 1. Next, the average particle size is about 10 μm
Of sendust powder and binder, respectively, in a volume ratio of sendust powder of 0.666, 0.5, 0.333, 0.2.
Then, the paste was mixed with an organic solvent, and the paste was dispersed on the spiral conductor and the center of the coil by a doctor blade method, and dried. Thus, a signal transmitting and receiving coil was obtained. The value of the volume ratio of 0.5 is the same as the paste used in Example 1.

FIG. 2 shows the result of measuring the inductance of the signal transmitting / receiving coil manufactured in Example 2 with an impedance analyzer.

As shown in FIG. 2, it can be seen that the inductance of the signal transmission / reception coil is improved as the content ratio (volume filling rate) of the sendust soft magnetic powder in the soft magnetic material sheet is increased.

Accordingly, it can be seen that forming a soft magnetic sheet on the spiral conductor and in the center of the coil has a great effect on improving the inductance of the signal transmitting / receiving coil.

[0030]

As described above, according to the present invention,
By sandwiching the spiral conductor between sheets made of a non-magnetic substrate and a soft magnetic material to form a sandwich structure that ensures flexibility, for example, a signal transmitting and receiving coil for a non-contact type IC card with high inductance can be easily obtained. If the conventional inductance value is sufficient, there is an advantage that the number of turns can be reduced, so that the manufacturing cost can be reduced and the coil size can be reduced.
Very useful.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a signal transmitting / receiving coil for a non-contact type IC card according to an embodiment of the present invention. FIG. 1A is a transparent perspective view.
FIG. 1B is a cross-sectional view taken along line AA of FIG.

FIG. 2 is a diagram showing a relationship between a volume filling ratio of soft magnetic powder in a soft magnetic material sheet and an inductance of a transmitting and receiving coil according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal transmission / reception coil 2 Non-magnetic substrate 3 (spiral-shaped) conductor 4 Terminal 5 Center part (of coil) 6 Soft magnetic sheet 7 Core (of coil)

Claims (3)

[Claims] 1. A non-contact type signal transmitting / receiving coil provided with a spiral conductor, wherein the spiral conductor is sandwiched between a non-magnetic substrate and a soft magnetic sheet in a sandwich structure, and A non-contact type signal transmitting / receiving coil, wherein a part of the soft magnetic material sheet fills a central portion of a spiral conductor to form a core of the spiral coil. 2. The soft magnetic sheet is made of a paste in which a mixture of a soft magnetic powder and a binder is dispersed in an organic solvent, and is prepared by applying the paste from above the spiral conductor. 2. The method for manufacturing a non-contact type signal transmitting / receiving coil according to claim 1, wherein: 3. A non-contact type IC card comprising the signal transmission / reception coil according to claim 1.