JP2000269037A - Thin type coil and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin type coil and a method of manufacturing the same, wherein a thinner multilayer coil than a thin type coil using a printed wiring board can be obtained, and wherein thin type coils can be manufactured at a low cost and a high yield due to the absence of warpages, cracks and chips which are present in a thin type coil using a ceramic board. SOLUTION: A ceramic powder is blended with an organic binder or a binder, such as water glass and formed into sheet-shaped composite sheets 1 using a film-forming machine, a printing machine, or the like. Using conductors, planar coils 2a, 2b and 2c are formed on the surfaces of the sheets 1. A plurality of coil boards 10a, 10b and 10c made of these sheets 1 are superposed upon another. During the superposing operation, the coils 2a, 2b and 2c are connected to one another through through-holes 3a, 3a', 3b and 3b' and 3b", and 3c and 3c", thereby preparing a multilayer coil. The multilayer coil is made rigid by thermal compression using a hot press or the like after lamination. Through such a manufacturing method and structure design, a thin type multilayer coil 10 can be obtained without sintering, and hence IC cards and antennas for portable terminals can be provided in small and thin sizes as well as at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin coil and a method of manufacturing the same, and more particularly, to a thin coil used for an IC card, a portable terminal, or the like and constituting an antenna, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a conventional thin coil, a printed circuit board made of a fluorine resin or an epoxy resin has been used.

FIG. 2 is a perspective view schematically showing a thin coil using a conventional printed board made of an organic material. As shown in FIG. 2, the conventional thin coil 50 is
1 and a conductor 52 formed of a spiral conductive pattern formed on the printed board.

However, in the thin coil shown in FIG.
There are limits to reducing the thickness of the printed circuit board 51,
It is also difficult to form a multilayer coil.

[0005] Therefore, ceramic printed circuit boards have come to be used in view of improvement in thickness reduction and formation of multilayer coils and three-dimensional coils.

As a ceramic substrate material used for a ceramic printed circuit board, an alumina-glass ceramic or the like is used (see Japanese Patent Application Laid-Open No. 11-027041).

FIG. 3 is an exploded perspective view showing the structure of a thin multilayer coil using a conventional ceramic substrate.
As shown in FIG. 3, a spiral-shaped conductor pattern is formed on each of the ceramic sheets (composite sheets) 53, and the composite sheets 53 are overlapped to provide each conductor pattern with a wall portion made of a conductor. Or through holes 54a, 54a ', 54b, 54b', 54b '
, 54c, 54c ', and after sintering, the through holes 54a, 54a', 54b, 54b ', 54b'
', 54c, 54c' are filled with a conductor, and the lead terminals 5
6a and 56b are completed. To reduce the sintering temperature to 900 to 1100 ° C. during the sintering, an alumina-glass ceramic is used as a material for the ceramic sheet.

As in the case of FIG. 3, a laminated coil in which a plurality of thin coils each having a spiral coil formed on an insulating substrate and these spiral coils are connected through through holes is disclosed in Japanese Patent Application Laid-Open No. 167313
And Japanese Patent Application Laid-Open No. 58-67007 are known.

[0009]

However, in the case of such a ceramic substrate, a sintering step as a ceramic has always been adopted. For this reason, the finished board
Problems such as warping, cracking and chipping were always present.

On the other hand, glass-based ceramics can be sintered at a relatively low temperature.
Sintering at a temperature such as 00 degrees was required.

Further, alumina which compensates for these disadvantages
Glass-based ceramics need to use noble metals, such as platinum and palladium, as conductors in order to sinter in the air at 900 to 1100 ° C., which increases the material cost,
It also has disadvantages such as warpage, cracking and chipping.

It is an object of the present invention to provide a thin coil capable of obtaining a multilayer coil which is thinner than a thin coil using a printed circuit board, and a method for manufacturing the same.

Another technical problem of the present invention is that
It is an object of the present invention to provide a thin coil which can be manufactured at a low cost without warpage, cracking or chipping as compared with a thin coil using a ceramic substrate, and can be manufactured at low cost, and a method of manufacturing the thin coil.

[0014]

According to the present invention, a conductor made of a conductive material having a predetermined pattern is formed on a composite sheet which becomes an insulating substrate in which ceramic powder and a binder are uniformly dispersed. A thin coil obtained by subjecting the composite sheet to a rigid treatment is obtained.

According to the present invention, in the thin coil, a plurality of the composite sheets are provided, and the composite sheets are connected to each other through through holes formed in the sheets to form a multilayer or single-layer coil. A thin coil is obtained by forming a laminate by superimposing the laminate and forming the laminate by the rigidification treatment.

According to the present invention, in any one of the thin coils, the conductor is formed by screen printing or vapor deposition of the conductive material, and the stiffening treatment includes hot pressing the composite sheet. A thin coil characterized by comprising:

According to the invention, in any one of the thin coils, a powder of a ceramic material having a high dielectric constant is used as the ceramic, and the insulating substrate is higher than a resin substrate used for a printed circuit board. A thin coil characterized by having a dielectric constant is obtained.

Further, according to the present invention, in the thin coil, a thin coil is obtained, in which the ceramic is made of at least one of alumina, titania, barium titanate, and a relaxer ceramic.

According to the present invention, in any one of the thin coils, the conductive material is made of at least one of silver, gold, copper and nickel.

Further, according to the present invention, in any one of the thin coils, a thin coil characterized by using a conductive paste as the conductive material is obtained.

According to the present invention, in any one of the thin coils, a solder paste is used as the conductive material, and the conductivity is increased by heating to a temperature at which the solder melts. A thin coil is obtained.

Further, according to the present invention, a ceramic sheet and a binder are uniformly dispersed on a composite sheet.
A method for manufacturing a thin coil is obtained, wherein a conductor made of a conductive material having a predetermined pattern is formed, and the composite sheet is formed into an insulating substrate by performing a rigidizing treatment.

According to the present invention, in the method of manufacturing a thin coil, a plurality of the composite sheets are formed, and the plurality of the composite sheets are connected to each other through through holes formed in the sheets. To form a laminated body by forming a multilayer or a single-layer coil, the composite sheet is formed on an insulating substrate by subjecting the laminated body to the rigidizing treatment, and the laminated body is formed as one rigid body. And a method of manufacturing a thin coil.

Further, according to the present invention, in any one of the above-described methods for manufacturing a thin coil, the conductor is formed by screen printing or vapor deposition of the conductive material, and the stiffening treatment is performed by the composite sheet or the laminate. A method for producing a thin coil, comprising subjecting a body to hot pressing, is obtained.

According to the invention, in any one of the above-described methods for manufacturing a thin coil, a powder of a ceramic material having a high dielectric constant is used as the ceramic powder, and the insulating substrate is a resin used for a printed board. A method of manufacturing a thin coil having a higher dielectric constant than a substrate is obtained.

According to the present invention, in the method for manufacturing a thin coil, the ceramic powder may be made of alumina,
A method for producing a thin coil, comprising at least one powder of titania, barium titanate, and a relaxor-based ceramic is obtained.

According to the present invention, in any one of the above-described methods for manufacturing a thin coil, silver or silver may be used as the conductor.
A method for manufacturing a thin coil, characterized in that at least one of gold, copper and nickel is used.

According to the present invention, there is provided a method for manufacturing a thin coil according to any one of the above-described methods for manufacturing a thin coil, wherein a conductive paste is used as the conductive material.

Further, according to the present invention, in any one of the above-described methods for manufacturing a thin coil, the conductive material may include:
A method of manufacturing a thin coil, characterized by using a solder paste and increasing the conductivity of the solder by heating to a temperature at which the solder melts, is obtained.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing a schematic configuration of a thin multilayer coil according to an embodiment of the present invention.

Referring to FIG. 1, a thin multilayer coil 10 is shown.
Is prepared by mixing a ceramic powder, an organic binder or a binder such as water glass, and water or an organic solvent as a solvent for the binder to form a slurry, and using a doctor blade method or a printing method to form a slurry. The composite sheet 1 is formed by a typical sheet forming method (film forming method). A predetermined pattern 2a, 2 made of a conductive material having a coil function is formed on the surface of the composite sheet 1 by screen printing or vapor deposition.
b, 2c are formed. Next, the patterns 2a, 2b,
Coil substrate 10 made of composite sheet 1 with 2c formed
a, 10a, and 10a are overlapped to form a laminate.
At this time, a through hole (through hole) 3 forming a contact portion
a, 3a ', 3b, 3b', and 3b '' are filled with a conductive material in advance, and the through holes are formed so as to overlap each other. In this way, the coils of each composite sheet 1 are connected to each other.

Reference numerals 5a and 5b are lead-out terminals formed of lead wires. When the coil is formed as a single layer, the thickness of the composite sheet 1 is made relatively thick. Also,
In the above example, a spiral-shaped coil pattern is formed. However, a zigzag coil may be used, and the shape may be determined according to desired characteristics. The present invention is limited to the coil shape. It is not something to be done.

Next, since the composite sheet 1 is flexible as it is, the composite sheet 1 is thermo-compressed by a hot press machine to have rigidity. At this time, the ceramic layer,
A construction method of forming a conductor pattern may be employed. In this case, thermocompression bonding is not necessarily required.

Here, as the conductive material of the pattern forming the coil, since there is no sintering step, if the conductor is a conductor,
Any material can be used, and base metals such as nickel and copper can be used. Alternatively, a material such as a conductive adhesive such as silver, gold, or carbon may be used. Further, a solder paste can be used, but in this case, it is desirable to heat to the melting point of the solder (about 240 ° C.), so that the binder forming the composite sheet is made of a material that is not affected by the temperature. Is used.

If a ceramic having a high dielectric constant, for example, alumina, titania, barium titanate, or a relaxor-based dielectric ceramic is used as the ceramic material for the composite sheet, the composite sheet before sintering is used. 1
Even in this case, a dielectric constant higher by one digit or more can be obtained as compared with a conventionally used fluororesin or epoxy resin substrate.

As described above, if a large dielectric constant can be obtained,
The coil shape can be reduced in size, resulting in advantages.

Next, a specific example of manufacturing a thin multilayer coil according to the embodiment of the present invention will be described.

In the thin multilayer coil according to the embodiment of the present invention, barium titanate powder was used as ceramic. To this, 3% of polyvinyl butyral was added as a binder, and a slurry obtained by dispersing and mixing with a homomixer using ethyl and cellosolve as a solvent to a thickness of 50 μm by a doctor blade method was prepared. 1 was formed. In advance, through holes 3a,
A 150-micron through hole was formed at a predetermined position so as to be 3a ', 3b, 3b', 3b '', 3c, 3c '. These through holes were filled with a conductive adhesive. Three composite sheets 1 are prepared, and the respective surfaces thereof are coated with conductive resin using planar coils 2a, 2b, 2c.
To form coil substrates 10a, 10b, and 10c, respectively. The three layers of planar coils 2a, 2b, 2c form through holes 3a, 3a ', 3b, 3b', 3b '', 3c, 3
c ', and the three coil substrates 10a, 10b, 10
c was thermocompressed with heat and pressure using a hot press machine.

Through the above steps, a multilayer thin coil having rigidity and being usable as an antenna of a portable terminal or an IC card was obtained.

As described above, the thin coil according to the embodiment of the present invention can be made much thinner than a thin coil using a printed substrate made of a conventional organic material, and the dielectric constant of the substrate can be reduced. Can also be adjusted.

Further, according to the embodiment of the present invention, compared with another conventional thin coil using a ceramic substrate, the production cost for sintering is unnecessary, and there are no problems such as warpage, cracking and chipping.

Further, according to the thin coil of the embodiment of the present invention, the cost of the coil material does not need to use an expensive noble metal, so that a thin coil with much lower cost is achieved.

[0044]

As described above, according to the present invention,
It is possible to provide a thin coil in which a multilayer coil can be further thinned as compared with a thin coil using a conventional printed circuit board, and a method for manufacturing the same.

Further, according to the present invention, the sintering step can be omitted as compared with a conventional thin coil using a ceramic substrate, so that there is no warpage, cracking or chipping, and an expensive noble metal is used for the coil material. Since there is no need to provide such a coil, it is possible to provide a multilayer thin coil and a method for manufacturing the same, which have the advantage that they can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a schematic configuration of a thin multilayer coil according to an embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a thin coil using a conventional printed board made of an organic material.

FIG. 3 is an exploded perspective view showing a configuration of a thin multilayer coil using a conventional ceramic substrate.

[Explanation of symbols]

1 Composite sheet 2a, 2b, 2c Pattern 3a, 3a ', 3b, 3b', 3b ", 3c, 3c '
Through hole 5a, 5b Lead terminal 10 Multilayer coil 10a, 10b, 10c Coil board 50 Thin coil 51 Printed board 52 Conductor 53 Ceramic sheet (composite sheet) 54a, 54a ', 54b, 54b', 54b ", 5
4c, 54c 'Through-hole 56a, 56b Lead terminal

Claims (16)

[Claims] 1. A conductor made of a conductive material having a predetermined pattern is formed on a composite sheet serving as an insulating substrate in which ceramic powder and a binder are uniformly dispersed, and the composite sheet is subjected to a rigidifying treatment. A thin coil characterized in that: 2. The thin coil according to claim 1, further comprising a plurality of the composite sheets, wherein the composite sheets are connected to each other through through holes formed in the sheets to form a multilayer or single-layer coil. Characterized in that the laminated body is formed by stacking the laminated body as described above, and the laminated body is subjected to the rigidifying treatment. 3. The thin coil according to claim 1, wherein the conductor is formed by screen printing or vapor deposition of the conductive material, and the stiffening treatment includes hot pressing the composite sheet. A thin coil characterized by the following. 4. The thin coil according to claim 1, wherein a powder of a ceramic material having a high dielectric constant is used as the ceramic, and the insulating substrate is
A thin coil having a higher dielectric constant than a resin substrate used for a printed circuit board. 5. The thin coil according to claim 4, wherein the ceramic is made of at least one of alumina, titania, barium titanate, and a relaxer ceramic. 6. The thin coil according to claim 1, wherein the conductive material is made of at least one of silver, gold, copper, and nickel. 7. The thin coil according to claim 1, wherein a conductive paste is used as the conductive material. 8. The thin coil according to claim 2, wherein a solder paste is used as the conductive material, and the conductive material is heated to a temperature at which the solder melts to increase the conductivity of the solder. 9. A conductor made of a conductive material having a predetermined pattern is formed on a composite sheet in which ceramic powder and a binder are uniformly dispersed, and the composite sheet is subjected to a stiffening treatment so that the composite sheet is formed on an insulating substrate. A method for manufacturing a thin coil, wherein 10. The method for manufacturing a thin coil according to claim 9, wherein a plurality of the composite sheets are formed, and the plurality of the composite sheets are connected to each other through through holes formed in the sheets to form a multilayer. Alternatively, a laminated body is formed by superimposing so that a single-layer coil is formed, and the composite sheet is formed on an insulating substrate by subjecting the laminated body to the rigidizing treatment, and the laminated body is formed as one rigid body. A method for producing a thin coil. 11. The method for manufacturing a thin coil according to claim 9, wherein the conductor is formed by screen printing or vapor deposition of the conductive material, and the stiffening treatment heats the composite sheet or the laminate. A method for producing a thin coil, comprising performing a press treatment. 12. The method for manufacturing a thin coil according to claim 9, wherein a powder of a ceramic material having a high dielectric constant is used as the ceramic powder, and the insulating substrate is a printed circuit board. A method for manufacturing a thin coil having a higher dielectric constant than a resin substrate used. 13. The method of manufacturing a thin coil according to claim 12, wherein the ceramic powder comprises at least one powder of alumina, titania, barium titanate, and a relaxer ceramic. Manufacturing method. 14. The method of manufacturing a thin coil according to claim 9, wherein the conductor comprises:
A method for manufacturing a thin coil, comprising using at least one of silver, gold, copper, and nickel. 15. The method for manufacturing a thin coil according to claim 9, wherein a conductive paste is used as the conductive material. 16. The method for manufacturing a thin coil according to claim 9, wherein a solder paste is used as the conductive material, and the conductivity is increased by heating to a temperature at which the solder melts. Manufacturing method for thin coils.