JPH08147619A - Magnetic head - Google Patents

Abstract

PURPOSE: To obtain a magnetic head in which a magnetic path is miniaturized and whose output-to-noise characteristic is good by a method wherein a coil which is formed by a thin-film formation method is arranged around the magnetic coupling part of an upper-part core to a lower-part core. CONSTITUTION: In a magnetic head 10, a closed magnetic circuit is formed of an upper-part core 12 provided with a sliding face comprising a magnetic gap and of a lower-part coil comprising a thin-film coil 13 which is formed by a thin-film formation method. In a core 14, two pairs of regulation grooves 19A, 19B, 20A, 20B which regulate the width and the thickness of a base 18 are formed. The coil 13 is derived to the outside of the head 10 in such a way that a derivation line 25 which is composed of a conductive film is formed inside the grooves 19A, 19B, and the coil 13 and the derivation line 25 are connected directly in coil connection points 13A, 13B. Thereby, it is possible to obtain the magnetic head in which a magnetic path is made short, whose cross-sectional area can be reduced and whose characteristic is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, and more particularly to a magnetic head suitable for use in a VTR magnetic head.

[0002]

2. Description of the Related Art Today, a video tape recorder (hereinafter referred to as V
(TR) has started to be digitized by the progress of image compression technology and magnetic recording, and has become popular in consumer devices.

In magnetic recording of a digital VTR, high-speed slidability of the tape with respect to the head due to a high transfer rate requirement and wide band of the signal are required, and the magnetic head has an output-noise characteristic at high frequency (hereinafter, C / N characteristic). ) Is an issue.

As a magnetic head satisfying these characteristics,
A magnetic head 100 whose main part is shown in FIG. 11 can be considered.
The magnetic head 100 shown in FIG. 11 is a thin film magnetic head (hereinafter referred to as TFH) which has been put to practical use for a hard disk drive, and has a lower magnetic film 1 on a substrate (not shown).
01, the thin film coil 102, the upper magnetic film 104, and the terminal 106 are laminated via an insulating film (not shown). The lower magnetic film 101 and the upper magnetic film 10
A magnetic gap G is formed between the four. Since such a TFH 100 has a short magnetic path and a low inductance, it can be said that the TFH 100 has good C / N characteristics.

[0005]

However, there is a problem that a sufficient gap depth D cannot be secured against abrasion due to high-speed sliding of the recording medium. Even if the gap depth D is increased, the upper and lower magnetic films are not formed. 101,1
The small cross-sectional area of 04 causes a problem of magnetic saturation during recording.

In the conventional analog VTR, the magnetic head 110 shown in FIG. 12 which is compatible with a metal tape and has an excellent sliding characteristic is predominant. This magnetic head 110 is
Generally, it is called an MIG (Metal In Gap) head, and a high saturation magnetic flux density metal film 112 is formed on each magnetic gap forming surface of a pair of core halves 111, and is abutted via the magnetic gap G. There is. This M
The IG head 110 can increase the gap depth D,
The problem of magnetic saturation during recording does not occur, but digital VT
When considering the miniaturization of the magnetic path as a magnetic head for R to cope with a high frequency signal, the size (X × Y) of the winding window 114 is at least in consideration of the diameter of the practical winding material. A size of about 0.25 × 0.25 [mm ² ] or more is required, and it is obviously difficult to make the size as small as the TFH100 described above.

In view of the above problems, it is an object of the present invention to solve the problem of magnetic saturation during recording and to provide a magnetic head having a small magnetic path and good C / N characteristics.

[0008]

In order to solve the problems conventionally held and to achieve the above-mentioned object, a magnetic head of the present invention comprises a first core having a magnetic body joined through a magnetic gap. And a second core having a magnetic material, and a coil formed by a thin film forming method is arranged around a magnetic junction between the first core and the second core.

Further, in the above structure, the joint portion of the second core includes a pair of first restricting grooves and a pair of second grooves formed so as to intersect with the first restricting grooves. The joint area is regulated.

Further, in this structure, the conductive film is arranged in a portion of the joint portion of the second core regulated by the first regulating groove.

Further, in this structure, a part of the conductive film is connected to a part of the coil.

Further, in this structure, a part of the conductive film is exposed on the side surface or the bottom surface of the magnetic head.

Further, in the above structure, the second core is filled with glass in a portion removed by the first and second restriction grooves.

Further, in this structure, the coil is provided on the surface of the glass which is joined to the first core.

Further, in the above structure, the first core is formed by joining two core halves with a gap therebetween, and the joining portion between the first core and the second core is two. One is provided.

Further, in this structure, the area of one of the joints is set to 1 × 10 ^-2 mm ² or less.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a magnetic head showing a first embodiment of the present invention. The magnetic head 10 of this embodiment is
A closed magnetic circuit is formed by the upper core 12 having the sliding surface having the magnetic gap G and the lower core 14 having the thin film coil 13 formed by the thin film forming method. The upper core 12 is M
Core halves 12A, 12B made of n-Zn ferrite
And a high saturation magnetic flux density metal alloy film (hereinafter referred to as a magnetic film) 16 such as sendust, permalloy, etc., which are respectively laminated on the gap forming surfaces of the core halves 12A, 12B, and the core halves 12A, 12B, with the magnetic films 16 facing each other. It has a MIG structure including the glass 18 to be joined together. A magnetic gap G is formed between the magnetic films 16 and 16. If the thickness H of the upper core 12 is too thick, the magnetic path formed with the lower core 14 becomes large, so H = 0.
It is preferable to suppress it to 2 mm or less. The method of restricting the track width of the upper core 12 can be the same as that of the conventional MIG head. The embodiment shown in FIG. 1 shows a so-called parallel MIG type having a magnetic film parallel to the magnetic gap G, and the track width is restricted by a track restriction groove having an inclined surface. In addition, FIG.
It is also applicable to the MIG type magnetic heads shown in (b) and (c). The magnetic head shown in FIG.
G type, core half 21 due to track restriction groove
It has a magnetic film 16 continuous to one inclined surface 21a formed on A and 21B. The magnetic head shown in FIG. 2B is a MIG type in which the magnetic gap G is formed by the magnetic film 16 which is not parallel to the magnetic gap G. Figure 2
The magnetic head shown in (c) is a parallel MIG type having magnetic films 16 only on both sides of the magnetic gap G.

Returning to FIG. 1, the width of the magnetic path of the base 18 made of ferrite (the length in the medium sliding direction with respect to the magnetic head 10) is set so that the lower core 14 has a short magnetic path and a small cross-sectional area. And a pair of regulation grooves 19 for regulating the thickness (length in the direction orthogonal to the medium sliding direction)
A, 19B, 20A and 20B are formed. The restriction grooves 19A, 19B, 20A, 20B will be described later in detail. Here, if the connecting surface of the lower core 14 for forming the magnetic path with the upper core 12 is made large, the resistance component increases due to the length of the thin-film coil having a large specific resistance, and the magnetic component also increases. Since the inductance increases as the cross-sectional area of the path increases, it is necessary to keep the area below 0.1 × 0.1 = 1 × 10 ^-2 [mm ² ]. On the contrary, if it is made too small, the magnetic flux density becomes high and the influence of magnetic saturation becomes large. In order to prevent this effect, the connection area is 0.0
2 × 0.02 = 4 × 10 ^-2 [mm ² ] or more is required.

The thin film coil 13 is pulled out to the outside of the head 10 by a regulating groove 19 for regulating the magnetic path width of the lower core 14.
This is performed by providing a lead wire 25 made of a conductive film in A and 19B, and at the coil connection points 13A and 13B.
3 and the lead wire 25 are directly connected.

The connection between the thin film coil 13 and the lead wire 25 will be described in detail later in a manufacturing method, but is automatically performed when the thin film coil 10 is formed on the lower core 14,
It is possible to simplify the drawing of the thin film coil 13 to the outside of the head 10. With this structure, the lead wire 25 of the thin-film coil 13 is guided to the side surface of the lower core 14. Therefore, if the shape of the restriction grooves 19A and 19B is devised, it can be drawn from a relatively free place.

Next, FIGS. 3 (a) to 3 (f) and 4 (g) to
A method of manufacturing the lower core 14 will be described with reference to (k).

First, as shown in FIG. 3A, the surface of the ferrite plate 30, which is a ferromagnetic oxide magnetic material, is polished.

Next, as shown in FIG. 3B, a plurality of grooves 19A and 19B for restricting the magnetic path width of the lower core 14 are inserted in parallel. However, the restriction grooves 19A and 19B are 1 in processing.
The groove of the book is formed by grinding.

Then, as shown in the cross section of the main part of FIG. 3 (c), SiO ₂ , Cr ₂ O ₃ and Ti are formed on the surface of the plate 30.
An insulating film 31 made of O ₂ or the like is formed by a vacuum film forming technique,
Further, subsequently, a base film 32 such as Cr is formed on the insulating film 31.
To form. The base film 32 is formed to favorably stack the next conductive film 33. Conductive film 33
Is made of Cu, Ni, Au or the like, and is formed on the base film 32 by plating. The conductive film 33 becomes the lead wire 25 (FIG. 1) of the thin film coil 13 when the head 10 is completed, and the thickness is set so that the resistance value is preferably 1Ω or less. After plating, a protective film 34 is formed on the surface of the conductive film 33 by a vacuum film forming technique such as SiO ₂ , Cr ₂ O 3, TiO ₂ or the like so that the conductive film 33 is not oxidized. In this step, the conductive film 33 is formed by plating because it requires about 5 to 10 μm and it is desired to shorten the film forming time, but it may be formed by a vacuum film forming method such as sputtering or vapor deposition.

In the next step, as shown in FIG.
A winding groove 35 for forming the thin film coil 13 is formed in parallel with the center of each convex portion 30a of the plate 30 whose magnetic path width is restricted. The groove 35 is processed by grinding. The depth of the groove 35 is preferably 50 μm or less because the magnetic path is enlarged if it is too deep.

In the next step, as shown in FIG. 3 (e), a plurality of regulating grooves 20A, 20B for regulating the thickness of the magnetic path are arranged in parallel and perpendicular to the regulating grooves 19A, 19B. Form. The restriction grooves 20A and 20B are the restriction grooves 1
Steps are provided for 9A and 19B, and one groove is formed by grinding in terms of processing.

When the magnetic gap G has an azimuth angle θ, the regulation grooves 20A and 20B are formed to be inclined by the azimuth angle θ as compared with the above case. That is, FIG.
As shown in (e ′), the restriction grooves 20A and 20B may be formed by inclining the restriction grooves 19A and 19B by α (= 90 ° −θ). The magnetic gap G has an azimuth angle θ.
In the case of having the above, the reason why the restriction grooves 20A and 20B are formed by inclining by the azimuth angle θ is as follows. That is, if the thickness of the core when the magnetic gap G does not have an azimuth angle as shown in FIG. 3 (e ₁ ) is T,
As shown in (e ₂ ), when the magnetic gap G has a large azimuth angle, the thin film coil 13 may be cut when the core is cut with the core thickness T described above. In that case, predetermined characteristics may not be obtained, or the thin film coil 13 may not be completely insulated. Thus, when the magnetic gap G has a large azimuth angle, as described above, the restriction groove 20
If A and 20B are formed by inclining by azimuth angle θ,
As shown in (e ₃ ), the thin film coil 1 has a difference in that the joint portions 30 b and 30 c are formed in a parallelogram shape.
It is possible to form a predetermined core thickness T without cutting 3.

After that, as shown in FIG. 3 (f), the glass rod 36 is set on the processed grooves 19A, 19B and heated, and the processed grooves 19A, 19B, 2 on the plate 30.
All of 0A and 20B are embedded with glass. The glass rod 36 used here is preferably made of high melting point glass in consideration of the later joining of the upper core 12.

Next, as shown in FIG. 4G, unnecessary glass on the surface of the plate 30 is removed by surface grinding. As a result, the two magnetic path connecting portions 30b and 30c and the conductive film 33 are exposed as shown in detail in FIG.

Then, as shown in FIGS. 4 (h) and 4 (h '), in order to form the thin film coil 13 (FIG. 1), a photoresist (not shown) is applied to the surface of the glass 36' to form the thin film coil. After exposing the 13 patterns (FIG. 4 (h ′)), the photoresist portion is removed, and the exposed portion is processed by ion milling to form a spiral coil pattern recess 37 on the glass surface. To do. Depression amount is 4 ~
It is about 5 μm. The pattern of the thin-film coil 13 has a balance winding shape surrounding the two magnetic path connection portions 30b and 30c exposed on the surface, and both ends 37a and 37b of the recess 37.
Overlaps the exposed portion of the conductive film 33 adjacent to the magnetic path connecting portions 30b and 30c. Thereby, when the thin film coil 13 is formed in the recess 37, the thin film coil 13 and the conductive film 33 are formed.
Is automatically connected.

Next, as shown in FIG. 4 (i), plating is performed so that the metal film 38 of Cu, Au or the like having excellent conductivity is embedded in the spiral recess 37 with a thickness of about 6 μm. To form a film. Also in this case, the film may be formed by the vacuum thin film forming technique.

Next, as shown in FIGS. 4 (j) and 4 (j '), the metal film 38 is removed by polishing, and then Si is removed.
An insulating film 39 made of O ₂ , Cr ₂ O ₃ or the like is formed with a thickness of 1 μm or less by a vacuum film forming technique. Insulating film 39 1μ
The reason why it is formed with a thickness of m or less is that it does not affect the magnetic characteristics when the magnetic head 10 is formed by joining with the upper core 12. Through the steps up to this point, the pattern of the thin-film coil 13 as shown in FIG.
The terminal (lead wire 25) can be easily drawn out via the coil connection points 13A and 13B with respect to 3.

Then, the block 40 of the lower core is obtained by cutting along the broken line shown in FIG. 4 (k).

Next, a method of processing the upper core 12 will be described with reference to FIG.
A description will be given using (a) to (f). The manufacturing method described here basically conforms to the conventional manufacturing method of the MIG head, but since only the sliding portion needs to be taken out, the number of ferrite materials of the same size as the conventional one increases.

First, as shown in FIG. 5A, the surface of the plate 42 made of ferrite is flat-polished.

Then, as shown in FIG. 5B, a plurality of trapezoidal restriction grooves 43 for restricting the gap depth are formed in the plate 42 in parallel.

Further, as shown in FIG. 5C, the regulation grooves 44 for regulating the track width are formed in parallel at equal intervals on the surface of the plate 42 in the direction perpendicular to the regulation grooves 43.

Next, as shown in FIG. 5D, a base film (not shown) to be a diffusion prevention film is formed on the surface of the plate 42 by a vacuum film forming technique, and then a magnetic film such as sendust and permalloy is formed. 16 is deposited.

Then, as shown in FIG.
After forming a gap material (not shown) such as ₂ on the surface, a plate 42 ′ similarly processed on the opposite side is butted, and the glass rod 45 is used for butt joining by welding.

After that, as shown in FIG. 5 (f), the upper core block 46 as indicated by A, B, and C is taken out by cutting at a portion indicated by a broken line.

By processing the lower core block 40 and the upper core block 46 obtained by the steps described above with reference to FIGS. 3, 4 and 5, as shown in FIG. 6,
The magnetic head 10 is obtained.

In the step shown in FIG. 6A, a low melting point glass 48 is formed on the bonding surface of the lower core block 40 by a vacuum film forming technique, the blocks 40 and 46 are aligned, and then heat bonding is performed. As other joining means, if the environment resistance is satisfied, resin adhesion or a method of attaching a metal film to both block joining surfaces and joining at low temperature is also effective.

Thereafter, as shown in FIG. 6 (b), cylindrical grinding is performed on the sliding surface 46a side of the upper core block 46, and then cutting is performed along the broken line to obtain the magnetic head shown in FIG. 10 is obtained.

FIG. 9 shows a magnetic path 70 of the magnetic head 10 constructed as described above. As shown in FIG. 9, the upper core 12 connected through the magnetic path connecting portions 30b and 30c.
It can be seen that the magnetic path 70 formed in the lower core 14 and the lower core 14 is very short. Therefore, it is possible to supply a magnetic head having a small magnetic path and good C / N characteristics.

Further, the magnetic head 10 is divided into the upper core 12 and the lower core 14, and the coil formed by the thin film forming method is provided on the joint surface of the lower core 14 with the upper core 12. It is possible to facilitate the connection between the coil and the lead wire and improve the productivity of a magnetic head having a small magnetic path and good C / N characteristics.

Further, in the above embodiment, the thin film coil 13 is formed on the glass 36 'of the lower core 14 in order to surely and easily form the positioning, but it is formed on the upper core 12 side. It is also possible to join with the lower core 14.

Although the description of the process of assembling the magnetic head 10 to the head base is omitted, as shown in FIG. 7, the terminal lead to the printed circuit board 52 in the magnetic head 10 attached to the head base 50 is Au. This is performed by connecting the lead-out portion (conductive film) 25 exposed on the side surface of the magnetic head 10 and the terminal 52a on the printed circuit board 52 by wire bonding using a wire.

The magnetic head 10 obtained as described above
Table 1 shows the data obtained by comparing the characteristics of No. 1 with the MIG type magnetic head described in the conventional example. The mechanical characteristics are that the track width is 14 [μm] and the gap width is 0.2 [μm].
m] and the gap depth was set to 12 [μm]. The magnetic films 16 and 112 both used sendust. In addition, the output measurement is performed with a holding force Hc =
Using a vapor deposition tape of 1600 [Oe], the medium relative speed was 10.2 [m / s] and the frequency was 21 [MHz].

[0050]

[Table 1]

With respect to the number of turns of the coil, in order to make the inductance about 0.45 [μH], the conventional magnetic head can have 14 turns, while the configuration of the above embodiment can have 6 turns extra. It has low inductance. Although the direct current (DC) resistance increases with the use of the thin film coil, it has almost no effect, and the C / N characteristic is 2.
It was improved by 5 [dB]. The difference between these results can be evaluated as an effect of thinning the winding and miniaturizing the magnetic path of the lower core, because the sliding parts of both have the same structure.

Next, as for another embodiment, FIG.
This will be described with reference to (b) and (c). In the configuration shown in FIG. 8A, the shape of the base 18 of the lower core 10 is not an inverted T shape like the configuration of the embodiment shown in FIG. It is formed in a letter shape. With this configuration, the lead-out portion 25 of the thin-film coil 13 can be exposed on the bottom surface 14a of the lower core 14.

Further, as shown in FIG. 8B, the thickness of the lead-out portion 25 of the thin-film coil 13 is increased, or as shown in FIG. 8C, the conductive film 33 (lead-out portion 25) is made conductive. It is also possible to easily draw out the terminal by bringing the metal wire 60 having a certain shape into contact and embedding it in the glass 36 '.

FIG. 9 shows the magnetic path 70 in the configuration of the above embodiment. According to this FIG. 9, the magnetic path connecting portion 30b,
It can be seen that the magnetic path 70 formed in the upper core 12 and the lower core 14 connected via 30c is very short. Therefore, it is possible to supply a magnetic head having a small magnetic path and good C / N characteristics. When the influence of the increase in the inductance and the decrease in the reproduction efficiency due to the sneak of the leakage magnetic flux shown by 72 is considered, as shown in FIG. 10, the length W formed by joining the core halves 12A and 12B in the upper core 12 is Can be improved by making the magnetic field width L of the lower core 14 substantially the same. In this case, the core half 12A, 12B has a non-magnetic material such as ceramic 7 at both ends in the direction of medium sliding.
It is preferable to connect 4 together. For this ceramic 74, it is preferable to use Al ₂ O ₃ , TiO ₂ , or Ca-Ti based ceramics. The ceramic 74 is provided in consideration of wear, but it can be implemented with glass.

According to the embodiment described above, the upper core 1
The magnetic path of the entire magnetic head 10 can be miniaturized by reducing the thickness of 2 and reducing the length and cross-sectional area of the magnetic path of the lower core 14.

The lower core 14 (base 18) is made of Mn.
Since the magnetic path is formed of a ferromagnetic oxide magnetic material such as -Zn ferrite, the width and thickness of the magnetic path are regulated by a pair of two regulating grooves 19A, 19B, 20A, and 20B that are orthogonal to each other. It is possible to reduce the size of the road. The reason why ferrite is used for the base 18 is that it has a degree of freedom in processing shape and is suitable for multi-cavity production.

Further, the thin film coil 13 can be easily drawn out when the thin film coil 13 is formed by forming the conductive film 33 in the portion where the grooves 19A and 19B for regulating the width of the magnetic path of the lower core 14 are formed. Since the conductive film 33 and the thin film coil 13 are connected to each other, the productivity is excellent. The conventional thin film head is composed of a plurality of layers such as a lower magnetic film, a thin film coil, a terminal and an upper magnetic film, and has many steps even if only the thin film coil formation portion is seen. The layer can be formed as a single layer because it does not require terminal formation, and is obviously high in productivity.

Further, the terminal is taken out by connecting to the terminal 52a provided on the printed board 52 by utilizing the cross section of the conductive film 33 exposed on the side surface or the bottom surface of the lower core 14, and the magnetic path of the lower core 14 is taken out. Grooves 19A, 1 that regulate the width
If the shape of 9B is devised, the conductive film can be drawn out freely.

[0059]

As is apparent from the above description, according to the magnetic head of the present invention, the upper core and the lower core are separately configured, and the thin film is formed around the magnetic junction between the lower core and the upper core. Since the coil formed by the forming method is provided, it is possible to facilitate the connection of the lead wire of the coil and increase the productivity of the magnetic head having a small magnetic path and good output to noise (C / N) characteristics. it can.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic head of the present invention.

2 (a), (b) and (c) show examples of MIG type magnetic gap forming portions applicable to the magnetic head of the present invention.

3 (a) to 3 (f) show the manufacturing process of the lower core of the magnetic head shown in FIG. 1 together with FIGS. 4 (g) to 4 (k). (E ′) shows a modification of (e), and (e ₁ )
(E ₃ ) is an explanatory diagram thereof.

4 (g) to (k) show the manufacturing process of the lower core of the magnetic head shown in FIG. 1 together with FIG. 3 (a) to (f). (H ') and (j') show the top views of (h) and (j), respectively.

5A to 5F show a manufacturing process of an upper core of the magnetic head shown in FIG.

6A and 6B show a process of obtaining a magnetic head from an upper core and a lower core.

FIG. 7 shows a configuration in which a magnetic head is connected to a terminal formed on a printed board.

8A to 8C are views showing another embodiment of the magnetic head of the present invention.

FIG. 9 is a diagram showing a magnetic path in the magnetic head of the present invention.

FIG. 10 is a diagram showing still another embodiment of the magnetic head of the present invention.

FIG. 11 is a diagram showing an example of a conventional magnetic head.

FIG. 12 is a diagram showing an example of a conventional magnetic head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 magnetic head 12 upper core 13 thin film coil 14 lower core 16 magnetic film 18 base 19A, 19B regulation groove 20A, 20B regulation groove 25 extraction part

Claims (10)

[Claims] 1. A first core having a magnetic body and a second core having a magnetic body, which are joined to each other via a magnetic gap, wherein the first core and the second core are magnetic. A magnetic head characterized in that a coil formed by a thin film forming method is arranged around the joint. 2. The joint portion of the second core according to claim 1, comprising a pair of first restriction grooves and a pair of second grooves formed to intersect with the first restriction grooves. A magnetic head having a joint area regulated. 3. The magnetic head according to claim 2, wherein a conductive film is provided in a portion of the joint portion of the second core regulated by the first regulation groove. 4. The magnetic head according to claim 3, wherein a part of the conductive film is connected to a part of the coil. 5. The magnetic head according to claim 4, wherein a part of the conductive film is exposed on a side surface of the magnetic head. 6. The magnetic head according to claim 4, wherein a part of the conductive film is exposed at a bottom surface of the magnetic head. 7. The second core according to claim 2, wherein:
A magnetic head characterized in that the portion removed by the first and second regulating grooves is filled with glass. 8. The magnetic head according to claim 7, wherein the coil is provided on a joint surface of the glass with the first core. 9. The method according to claim 1, wherein the first
The core is formed by joining two core halves via a gap, and there are two joining portions between the first core and the second core. 10. The magnetic head according to claim 9, wherein one area of the joint portion is 1 × 10 ⁻² mm ² or less.