JP2002183696A - Method of manufacturing coil of ic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an antenna coil of an IC card from becoming a disconnection state and a short-circuit state in manufacturing process. SOLUTION: A first coil 7 is formed on a circuit sheet 1 by screen printing. While, a second coil 10 is formed on a printed wiring board 9 by a printed wiring means. An adhesive is applied on the first coil 7, and the printed wiring board 9 is adhered in layers to the first coil 7. At this time, a conductive adhesive is applied to a central part 7a of the first coil 7 and a tip part 8a of one conductive passage 8 of a pair of conductive passages 8, and both end parts of the second coil 10 are connected to the first coil 7 and the conductive passage 8, simultaneously as with adhesion of the printed wiring board 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method of providing an antenna coil on a sheet constituting a surface layer of an IC card.

[0002]

2. Description of the Related Art In recent years, an IC card in which a semiconductor chip having functions such as a memory and a CPU is mounted on a card-like base has been developed and has already been put to practical use. This IC card has a three-layer structure including a circuit sheet on which a semiconductor chip is mounted by forming a circuit pattern, an intermediate sheet mounted on the circuit sheet, and a cover sheet mounted on the intermediate sheet. ing.

In the case of a non-contact type IC card, a circuit sheet is provided with an antenna coil for transmitting / receiving data to / from an external device by a radio signal or receiving power. Conventionally, this antenna coil is formed by screen printing using a conductive paste.

[0004] However, when the antenna coil is formed by screen printing, the interval between the coil wires cannot be reduced so much, and the coil becomes large. In order to reduce the size of the antenna coil so that the location of electronic components such as an IC chip can be freely selected, the antenna coil is formed of a two-layer laminated coil.

In order to reduce the size of the antenna coil, it is conceivable that the circuit sheet is formed of a printed wiring board and the antenna coil is formed by printed wiring means. It is necessary to avoid forming an antenna coil on the circuit sheet by the printed wiring means, since the printing applied to the circuit sheet to be formed is damaged in the step of etching the metal foil.

[0006]

The laminated coil has a configuration in which a first layer coil and a second layer coil are laminated on a circuit sheet via an insulating layer. When manufacturing this laminated coil, first, a first layer coil is formed on a circuit sheet by screen printing using a conductive paste.
Next, an insulating layer is formed on the first layer coil by screen printing using an insulating paste, and finally, a second layer coil is formed on the insulating layer by screen printing using a conductive paste.

[0007] According to this manufacturing method, the insulating layer is applied to the region that has been made uneven by providing the first layer coil, so that the surface of the insulating layer also becomes uneven.
And, since the second layer coil is formed on the uneven surface of the insulating layer by screen printing, the coil wire of the second layer coil is printed in a blurred state and becomes disconnected.
There is a risk that adjacent coil wires may be crushed and short-circuited.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a coil of an IC card in which the coil is not likely to be disconnected or short-circuited during the manufacturing process. Is to do.

[0009]

In order to achieve the above-mentioned object, the present invention provides a method for forming a first coil on a surface layer sheet, and then superposing a substrate on which a second coil is formed on the surface layer sheet. Since the second coil is connected to the first coil to form the antenna coil, when forming the second coil, there is no possibility of a disconnection state or a short circuit state.

As described above, since the antenna coil is constituted by the laminated coil, the first coil formed on the surface sheet is formed.
Even if the coil is formed by screen printing, it can be configured as an antenna coil having a required number of turns with the second coil formed on the substrate. Therefore, even if printing is performed on the surface layer sheet, there is no etching step, and there is no risk of damaging the printed portion. Further, the number of turns of the second coil can be increased by forming the second coil of the substrate by printed wiring means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The IC card of this embodiment has a three-layer structure including a circuit sheet 1, an adhesive sheet 2 as an intermediate layer, and a cover sheet 3, as shown in FIG. Of the above three layers of sheets 1 to 3,
The circuit sheet 1 is a back surface sheet, and the cover sheet 3 is a front surface sheet.
On the lower surface (the back side of the IC card) and the front surface of the cover sheet 3 (the front surface of the IC card), characters, patterns, and the like are printed.

The circuit sheet 1 is made of, for example, a polyester plastic sheet such as PET, and has an antenna coil 4 for receiving power from an external device by electromagnetic coupling and an electrostatic coupling on its upper surface, as shown in FIG. An electrostatic plate 5 for transmitting and receiving data to and from an external device is provided, and an IC chip 6 and the like are mounted.

The adhesive sheet 2 is made of, for example, a polyester-based hot-melt adhesive having a heat-melting property which becomes fluid when heated. This adhesive sheet 2
It has a function of protecting the antenna coil 4, the electrostatic plate 5, the IC chip 6, etc., and bonding the circuit sheet 1 and the cover sheet 3. The cover sheet 3 is made of a polyester-based plastic sheet such as PET, like the circuit sheet 1.

Here, a method of manufacturing the antenna coil 4 will be described. First, as shown in FIG. 1B, the first coil 7 is formed on the upper surface of the circuit sheet 1 by screen printing using a conductive paste, for example, a silver paste containing a silver filler. To form At the same time, a conductive path 8 for connecting the first coil 7 and the electrostatic plate 5 to the IC chip 6 is formed. In FIG. 1, the electrostatic plate 5 is omitted.

Next, an anisotropic conductive adhesive is applied to a mounting portion of the circuit sheet 1 on which the IC chip 6 is mounted, and the IC chip 6 is mounted thereon and thermocompression-bonded. Thereby, the IC chip 6 is adhered to the circuit sheet 1 and the IC chip 6 is
To the coil 7 and the electrostatic plate 5.

On the other hand, as shown in FIG. 1A, a printed wiring board 9 which is slightly larger than the area where the first coil 7 is formed.
Then, the second coil 10 is formed. The printed wiring board 9 is formed by attaching a metal foil to a thin flexible film as a base material, and the second coil 10 forms a coil pattern on the metal foil by a printing means.
The excess metal foil is removed by etching.

Then, as shown in FIG. 1C, an adhesive 11 is applied to a region of the circuit sheet 1 where the first coil 7 is to be formed, and the printed wiring board 9 is mounted thereon and adhered thereto. At this time, a conductive adhesive is applied to the central portion 7a of the first coil 7 and the tip 8a of one of the conductive paths 8 of the pair of conductive paths 8, whereby the above-described conductive adhesive is applied. The second coil 10 is connected in series to the first coil 7 simultaneously with the adhesion of the printed wiring board 9 to form the antenna coil 4. In addition to the one end of the antenna coil 4, the other end (the second coil (Outer end 10) is also a conductive path 8
Is connected to the IC chip 6 via the.

After connecting the first coil 7 and the second coil 10 to form the antenna coil 4 in this manner,
The adhesive sheet 2 and the cover sheet 3 are sequentially stacked on the circuit sheet 1, and the whole is thermocompression-bonded by a hot press device (not shown). Then, the hot melt adhesive forming the adhesive sheet 2 is melted and becomes fluid, so that the hot melt covers the IC chip 6, the printed wiring board 9 and the like without gaps. At the same time, the adhesive sheet 2 is formed to have a uniform thickness by applying pressure from both the upper and lower sides, and adheres the circuit sheet 1 and the cover sheet 3. Then, the adhesive sheet 2 is solidified by the subsequent cooling, and an IC card having a three-layer structure is manufactured as described above.

As described above, according to the present embodiment, the second coil 10 is formed on the printed wiring board 9 different from the circuit sheet 1 and is adhered to the circuit sheet 1. Only one layer of coils 7 and 10 need to be formed on the wiring board 9. For this reason, unlike the related art in which the second coil is further formed on the first coil via an insulating layer by screen printing, the second coil 10 may be disconnected or short-circuited. There is no. Further, since the second coil 10 is formed by the printed wiring means, the dimension between the lines of the second coil 10 and the width of the coil wire can be reduced, so that the number of turns can be increased and the entire antenna coil 4 can be made smaller. it can.

FIGS. 4 and 5 show second and third embodiments of the present invention, respectively. These embodiments differ from the first embodiment in the structure in which the printed wiring board 9 is bonded to the circuit sheet 1. That is, in the second embodiment shown in FIG. 4, the insulating layer 12 is screen-printed on the first coil 7, and the printed circuit board 9 is bonded by applying the adhesive 11 on the insulating layer 12 by screen printing. It is. In the third embodiment of FIG. 5, on the first coil 7,
It has a structure in which a film 14 made of, for example, PET, on which an adhesive 13 is adhered, is attached to both sides, and a printed wiring board 9 is attached to the film 14.

The present invention is not limited to the embodiment described above and shown in the drawings, but can be extended or modified as follows. The IC chip 6 is a printed wiring board 9
May be mounted on the circuit sheet 1 after being adhered to the circuit sheet 1. IC cards are not limited to those having a three-layer structure.
The second coil 10 may be formed by screen printing. The printed wiring board 9 may be the same size as the circuit sheet 1.

[Brief description of the drawings]

FIGS. 1A and 1B sequentially show a manufacturing process of an antenna coil according to a first embodiment of the present invention, wherein FIG. 1A is a perspective view of a printed wiring board viewed from below, FIG. (C) is a cross-sectional view of a state where the printed wiring board is bonded to a circuit sheet.

FIG. 2 is a plan view of a circuit sheet.

FIG. 3 is a sectional view of an IC card.

FIG. 4 is a view corresponding to FIG. 1 (c) showing a second embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 1 (c) showing a third embodiment of the present invention.

DESCRIPTION OF THE SYMBOLS In the drawing, 1 is a circuit sheet (sheet for surface layer), 4 is an antenna coil, 6 is an IC chip, 7 is a first coil, 9 is a printed wiring board, and 10 is a second coil.

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Claims (3)

[Claims] 1. A method of manufacturing an antenna coil for transmitting / receiving a signal to / from an external device to a surface sheet constituting a surface layer of an IC card among a plurality of sheets constituting an IC card by being superimposed. Forming a first coil on the surface sheet, forming a second coil on the substrate, stacking the substrate on the surface sheet, connecting the second coil to the first coil, A coil manufacturing method for an IC card, comprising an antenna coil. 2. The method for manufacturing a coil of an IC card according to claim 1, wherein the surface layer sheet is printed on a surface to be a surface of the IC card. 3. The IC card coil manufacturing method according to claim 1, wherein said substrate is formed of a printed circuit board, and said second coil is formed by printed wiring means.