JPH0774039A - Manufacture of rotary transformer - Google Patents

Abstract

PURPOSE:To obtain a manufacturing method, of a rotary transformer, which can automate a manufacturing process, which can reduce manufacturing costs and which can accommodate the smaller size and the higher density of coils due to the smaller size of the rotary transformer. CONSTITUTION:Ring-shaped recessed grooves 3A to 3E are formed on one face of a disc-shaped ferrite core 1, a conductive paste is printed and sintered on the ring-shaped recessed grooves 3A to 3E, ring-shaped conductive layers are formed, and spiral coils 6A to 6E are formed of the ring-shaped conductive layers by an etching operation. Thereby, the higher density of the spiral coils 6A to 6E is realized, and their manufacturing process can be automated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a rotary transformer, particularly in a magnetic recording / reproducing apparatus, in which a recording signal is supplied to the rotary magnetic head from the outside or the recording signal is derived from the outside. The present invention relates to a method for producing a rotary transformer suitable for use in.

[0002]

2. Description of the Related Art Conventionally, the following types of rotary transformers are known.

In the rotary transformer assembly proposed by the present applicant in Japanese Utility Model Publication No. 62-18013, a concentric circular groove is formed on one surface of a disk-shaped ferrite core constituting a rotor core or a stator core, and a wire rod is formed in the circular groove. A configuration in which a winding formed by winding is provided is disclosed.

Further, Japanese Patent Laid-Open No. 2-30 proposed by the present applicant
No. 8505, a core for a rotary transformer in which a sheet-shaped coil body formed by punching out a polymer sheet of a resin or the like having a conductor pattern in the same shape as the annular groove is fixed to the annular groove of a similar disk-shaped ferrite core. A device and method of making the same are disclosed.

Further, in JP-A-59-127812, a circular groove having a desired coil pattern is formed in advance in a disk-shaped ferrite core, the groove is filled with a conductor paste, and then the disk-shaped ferrite core. There is disclosed a method for manufacturing a rotary transformer, in which a coil is formed by firing and baking the conductor paste.

Further, in Japanese Patent Laid-Open No. 4-42908, a spiral groove having a desired coil pattern is previously formed in a disk-shaped ferrite core, and the groove is filled with molten metal or metal powder. A method of manufacturing a rotary transformer is disclosed in which a coil is formed by cooling after melting (sintering).

[0007]

By the way, the manufacturing method of the rotary transformer shown in each of the conventional examples has the following problems.

First, in the manufacturing method in which the coil is formed by using the wire material and arranged in the groove, it takes time and effort to form the coil,
The number of man-hours required for manual work increases, and automation is difficult.

Further, when a sheet-shaped coil body formed by forming a conductor pattern on a polymer sheet such as resin is used, there is a drawback that the manufacturing cost becomes high. There is a limit to the miniaturization.

Further, in the case where a groove of a coil pattern is formed in advance in a ferrite core and the groove is filled with a conductive paste or a molten metal to form a coil, it is practical to process the groove corresponding to the coil pattern. It is difficult, and at present it is considered difficult to commercialize.

In view of the above points, the present invention can realize the automation of the manufacturing process and the reduction of the manufacturing cost, and can cope with the miniaturization or high density of the coil (conductor pattern) accompanying the miniaturization of the rotary transformer. It is intended to provide a method for manufacturing a rotary transformer.

[0012]

In order to achieve the above object, a method of manufacturing a rotary transformer according to the present invention is such that at least one annular groove is provided on one surface of a disk-shaped magnetic core, and the annular groove is formed. It is characterized in that an annular conductive layer is formed by printing a conductive paste on and sintering it, and a conductor pattern is formed by the annular conductive layer by etching.

A through hole penetrating from the bottom surface of the annular groove to the back surface of the disk magnetic core is formed in the disk-shaped magnetic core, and the inside of the through hole and the annular groove are electrically conductive. The annular conductive layer may be formed by printing a paste and sintering it.

A silver paste may be used as the conductive paste.

[0015]

In the method of manufacturing the rotary transformer of the present invention, the conductive paste is printed and sintered (baked) in the circular groove of the disk-shaped magnetic core to form the circular conductive layer, and then the circular conductive layer is formed. The layer is etched to form a spiral conductor pattern or the like that serves as a coil in the annular groove. Since the process can be automated, it is suitable for mass production and the manufacturing cost can be reduced. Further, the number of turns and the line width of the conductor pattern to be the coil can be freely set by etching, and the coil can be downsized or the density can be increased. Therefore, a method of arranging a coil or a sheet-shaped coil body made of a conventional wire rod in an annular groove or a method of filling a groove formed corresponding to a coil pattern with a conductive paste or molten metal to form a coil Compared with, it is easy to manufacture and low cost, and is suitable for downsizing and thinning of rotary transformers.

Further, a through hole penetrating from the bottom surface of the annular groove to the back surface is formed in the disk-shaped magnetic core, and a conductive paste is printed and sintered inside the through hole and in the annular groove. By doing so, it is possible to simultaneously form the connecting lead portion integrated with the annular conductive layer formed in the annular concave groove, and to obtain the conductor pattern and the disk obtained by etching the annular conductive layer. It is possible to connect the terminal (or electrode) on the back surface of the magnetic core with its lead portion.

By using a silver paste as the conductive paste, it is not necessary to prevent the spiral conductor pattern after etching from being corroded by plating or the like, and good characteristics with low electric resistance can be obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a rotary transformer according to the present invention will be described below with reference to the drawings.

1 to 4 show a first embodiment of the present invention. 1 and 2, reference numeral 1 denotes a sintered disc-shaped ferrite core that serves as a rotor core or a stator core of a rotary transformer, a through hole 2 is formed in the center thereof, and a plurality of concentric circles are formed on one surface. Annular groove 3A
To 3E are formed. This annular groove 3A to 3
The groove width of E is set to an arbitrary width depending on the desired coil pattern according to the application. A high resistance ferrite is used as the disk-shaped ferrite core.

Next, as shown in FIG. 3, silver paste as a conductive paste is printed on the bottom surface of each of the annular recessed grooves 3A to 3E of the disc-shaped ferrite core 1 and sintered to form an annular conductive layer. 5A to 5E are formed. That is, a printing method such as screen printing or pad printing (printing by transfer) is used to print the silver paste on the bottom surfaces of the annular recessed grooves 3A to 3E and to dry the paste, which is repeated several times, or sintered or printed or sintered. By repeating the process several times, the annular conductive layers 5A to 5E having a desired thickness are obtained.

Then, as shown in FIG. 4, the annular conductive layers 5A to 5E are etched by a photoetching method to form spiral coils 6A to 6E as desired conductor patterns on the bottom surfaces of the annular recessed grooves 3A to 3E. Form each. That is, a photoresist is applied to the upper surfaces of the annular conductive layers 5A to 5E, a spiral pattern that circulates for several turns is exposed to the photoresist layer, and the portion other than the spiral pattern covered with the photoresist layer is removed by etching. Then, the spiral coils 6A to 6E are respectively formed. In the case of FIG. 4, the spiral coils 6A to 6E have different numbers of turns depending on the groove widths of the annular concave grooves 3A to 3E, and the wider the groove width, the greater the number of turns.

From the above, the plurality of annular concave grooves 3A to 3A
The stator or rotor of the rotary transformer having the spiral coils 6A to 6E on the bottom surface of E is obtained. The stator and the rotor of the rotary transformer are arranged close to each other so that the surfaces on which the annular groove is formed face each other, the stator is fixed, and the rotor is set to be rotatable by being attached to the rotating shaft.

Although not shown in the present embodiment, the circular annular grooves 3A to 3E of the disk-shaped ferrite core 1 are
From the bottom surface of the annular groove 3A to 3E to the ferrite core 1
A pair of through holes penetrating the back surface of the spiral coil are formed respectively, and the through holes serve as lead-out ends of the spiral coils.

According to the first embodiment described above, the ring-shaped conductive layer 5A matching the shapes of the ring-shaped concave grooves 3A to 3E by the printing method.
To 5E are formed, the shape of the annular recessed grooves 3A to 3E can be easily accommodated, and a small ferrite core can also be accommodated. Further, since each spiral coil 6A to 6E is formed by processing the annular conductive layers 5A to 5E burned on the bottoms of the annular recessed grooves 3A to 3E into a desired conductor pattern by photoetching, the number of windings of the coil is reduced. The line width can be set freely and the density of the spiral coil can be easily increased, making it suitable for downsizing and thinning of rotary transformers. Furthermore, since each of the above steps can be automated, it is suitable for mass production, and the manufacturing cost can be reduced.

Further, by using a silver paste as a conductive paste for forming the annular conductive layers 5A to 5E, the spiral coils 6A to 6 after photoetching are used.
It is not necessary to prevent E from being corroded by plating or the like, and the spiral coils 6A to 6E have low electric resistance and good characteristics can be obtained.

FIGS. 5 to 7 show a second embodiment of the present invention, in which a lead portion penetrating a disk-shaped ferrite core is formed simultaneously with the annular conductive layer. As shown in FIGS. 5 to 7, a through hole 2 is formed in the center of a disk-shaped ferrite core 1 that serves as a rotor core or a stator core of a rotary transformer, and a plurality of concentric circular annular grooves are formed on one surface. 3A to 3E are formed. The groove width of each of the annular concave grooves 3A to 3E is set to an arbitrary width according to a desired coil pattern according to the application. Further, wide portions 11 of which widths are partially wide are formed in the respective annular grooves 3A to 3E (only the wide portion 11 corresponding to the annular groove 3D is shown), and each of the wide portions 11 is formed. A pair of through holes 12 and 13 are formed in the vicinity of both side walls so as to penetrate from the bottom surface of the wide portion to the back surface of the disk-shaped ferrite core 1. In addition, the wide portion 11 has through-holes 12, 1
It is provided to secure a space for arranging 3.

Next, as shown in FIG. 6, silver paste as a conductive paste is printed on the bottom surface of each of the annular recessed grooves 3A to 3E of the disk-shaped ferrite core 1 and sintered to form an annular conductive material. The layers 5A to 5E are formed. That is,
Screen printing or pad printing (printing by transfer)
By printing the silver paste on the bottom surfaces of the annular grooves 3A to 3E by the printing method described above and then repeating the step of drying several times and then sintering, or by repeating the printing and sintering steps several times, a desired thickness is obtained. Ring-shaped conductive layers 5A to 5E
To get At that time, when printing the silver paste, the through holes 1
By sucking the inside of 2, 3 from the back surface of the disk-shaped ferrite core 1 with a negative pressure source, the silver paste is also filled in the through holes 12, 13 of the wide portion 11, and is sintered into an annular shape after printing. A pair of connecting lead portions 15 and 16 integrated with the conductive layers 5A to 5E are simultaneously formed.

Then, as shown in FIG. 7, the annular conductive layers 5A to 5E are etched by a photoetching method to form spiral coils 6A to 6E as desired conductor patterns on the bottom surfaces of the annular recessed grooves 3A to 3E. Form each. This step is the same as in the first embodiment described above.

In the case of the second embodiment described above, through holes 12 and 13 are formed in the disk-shaped ferrite core 1 so as to penetrate from the bottom surfaces of the annular concave grooves 3A to 3E to the back surface of the disk-shaped ferrite core 1, and Inside of the through holes 12 and 13 and the annular groove 3
By printing the conductive paste on A to 3E and sintering,
Ring-shaped concave grooves 3A to 3E Ring-shaped conductive layers 5A to 5 at the bottom
The connecting lead portions 15 and 16 integrated with E can be easily formed at the same time, and the connecting lead portions 15 and 16 can be formed simultaneously.
Can be used as a lead wire connecting to the ends of the spiral coils 6A to 6E.
6E and the terminals (or electrodes) on the back surface of the disk-shaped ferrite core can be connected by the respective lead portions 15 and 16. Other functions and effects are similar to those of the first embodiment described above.

FIG. 8 shows a third embodiment of the present invention. In this case, the spiral conductive layer 5 at the bottom of the circular recessed groove 3 of the circular ferrite core 1 is etched to form the spiral coil 6, and then the exposed portion of the spiral coil 6 is plated to prevent corrosion and soldered. And the like. When a conductive paste other than silver is used, the plating layer 7 is often needed. The overall structure of the annular ferrite core 1 and the like is similar to that of the first or second embodiment described above.

In the first and second embodiments, the disk-shaped ferrite core is provided with five annular concave grooves.
The number of the annular concave grooves can be appropriately changed according to the specifications of the rotary transformer. Similarly, the number of turns and the line width of the spiral coil can be appropriately changed according to the specifications of the rotary transformer.

Although the embodiment of the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes can be made within the scope of the claims. Let's do it.

[0033]

As described above, according to the method of manufacturing the rotary transformer of the present invention, at least one annular groove is provided on one surface of the disk-shaped magnetic core, and the conductive paste is placed in the annular groove. Since the ring-shaped conductive layer is formed by printing and sintering, and the conductor pattern is formed by the ring-shaped conductive layer by etching, the process can be automated, suitable for mass production, and the manufacturing cost can be reduced. it can. In addition, the number of turns, the line width, and the like of the conductor pattern serving as the coil can be freely set, and the coil can be downsized or the density can be increased. Therefore, an inexpensive rotary transformer suitable for miniaturization and thinning can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a disk-shaped ferrite core used in a first embodiment of a method for manufacturing a rotary transformer according to the present invention.

FIG. 2 is a sectional view showing a disk-shaped ferrite core.

FIG. 3 is a partial cross-sectional view showing a step of printing an annular conductive layer on the bottom surface of an annular groove of a disk-shaped ferrite core and sintering the layer.

FIG. 4 is a partial cross-sectional view showing a step of forming a spiral coil on the bottom surface of the annular concave groove of the disk-shaped ferrite core by subjecting the annular conductive layer to photoetching.

FIG. 5 is a partial plan view of a disk-shaped ferrite core used in a second embodiment of the present invention.

FIG. 6 shows an annular conductive layer printed on the bottom surface of the annular groove of the disk-shaped ferrite core and a lead portion printed in the through hole.
It is a fragmentary sectional view showing a process of sintering.

FIG. 7 is a partial cross-sectional view showing a step of performing photoetching on the annular conductive layer to form a spiral coil on the bottom surface of the annular concave groove of the disk-shaped ferrite core.

FIG. 8 is a partial enlarged cross-sectional view showing a step of providing a plating layer on the spiral coil according to the third embodiment of the present invention.

[Explanation of symbols]

 1 Disc-shaped ferrite core 2 Through hole 3A to 3E Circular groove 5A to 5E Circular conductive layer 6A to 6E Spiral coil 7 Plating layer 11 Wide part 12,13 Through hole 15,16 Lead part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Kinoshita 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Corporation (72) Inventor Shigeya Takahashi 1-13-1 Nihonbashi, Chuo-ku, Tokyo DC Inc.

Claims (3)

[Claims] 1. An annular conductive groove is provided on one surface of a disk-shaped magnetic core, and a conductive paste is printed in the annular groove and sintered to form an annular conductive layer. A method of manufacturing a rotary transformer, characterized in that a conductor pattern is formed of the annular conductive layer. 2. The disk-shaped magnetic core has a through hole penetrating from the bottom surface of the annular groove to the back surface of the disk-shaped magnetic core, and the inside of the through hole and the annular groove. The method of manufacturing a rotary transformer according to claim 1, wherein the annular conductive layer is formed by printing a conductive paste on the surface and sintering the conductive paste. 3. The method for manufacturing a rotary transformer according to claim 1, wherein the conductive paste is a silver paste.