JP2942156B2 - Magnetic head - Google Patents

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 Video tape recorders (hereinafter referred to as V
TR) has begun to be digitized due to advances in image compression technology and magnetic recording, and has become practically spread to consumer equipment.

[0003] In magnetic recording of a digital VTR, a high-speed sliding property of a tape with respect to a head due to a demand for a high transfer rate and a wide band of a signal are required. The challenge is how to earn).

[0004] 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 (TFH) practically used for a hard disk drive, and a lower magnetic film 1 is formed on a substrate (not shown).
1, a thin-film coil 102, an upper magnetic film 104, and a terminal 106 are laminated via an insulating film (not shown). The lower magnetic film 101 and the upper magnetic film 10
4, a magnetic gap G is formed. Such a TFH 100 can be said to have good C / N characteristics because the magnetic path is short and the inductance is kept low.

[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, and even if the gap depth D is increased, the upper and lower magnetic films cannot be secured. 101,1
The small cross-sectional area of 04 causes a problem of magnetic saturation during recording.

In a conventional analog VTR, a magnetic head 110 shown in FIG. 12 which is compatible with a metal tape and has excellent sliding characteristics is mainly used. This magnetic head 110
In general, this is called a 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 through a magnetic gap G. I have. This M
The IG head 110 can increase the gap depth D,
Although there is no problem of magnetic saturation during recording, 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 at least considering the diameter of a practical winding material. A size of about 0.25 × 0.25 [mm ² ] or more is required, and it is obviously difficult to reduce the size to the above-mentioned TFH100.

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

[0008]

SUMMARY OF THE INVENTION In order to solve the conventional problems and achieve the above object, a magnetic head according to the present invention comprises a first core having a magnetic body joined via a magnetic gap. And a second core having a magnetic material, wherein a coil formed by a thin film forming method is disposed around a magnetic junction between the first core and the second core,
The joint area of the core is restricted by a pair of first regulating grooves and a pair of second grooves formed to intersect with the first regulating grooves, and the joining of the second cores is performed. Part of the first
A conductive film is disposed in a portion regulated by the regulating groove, and a part of the conductive film is connected to a part of the coil.

[0009]

[0010]

[0011]

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

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

[0014] Further, in this configuration, the coil is provided on a joint surface of the glass with the first core.

In the above structure, the first core is formed by joining two core halves through a gap, and a joint between the first core and the second core is formed by two halves. One is provided.

Further, in this configuration, one area of the joining portion is set to 1 × 10 ⁻² mm ² or less.

[0017]

Embodiments of the present invention will be described below 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 the present embodiment
A closed magnetic path is formed by an upper core 12 having a sliding surface having a magnetic gap G and a lower core 14 having a thin film coil 13 formed by a thin film forming method. The upper core 12 is
Core halves 12A and 12B made of n-Zn ferrite
A high saturation magnetic flux density metal alloy film (hereinafter referred to as a magnetic film) 16 such as Sendust or Permalloy laminated on the gap forming surfaces of the core halves 12A and 12B, respectively. And a glass 18 to be joined. Note that a magnetic gap G is formed between the magnetic films 16. If the thickness H of the upper core 12 is too large, the magnetic path formed by the lower core 14 becomes large.
It is preferable to keep it to 2 mm or less. The method of regulating the track width of the upper core 12 can be performed in the same manner as the conventional MIG head. In the embodiment shown in FIG. 1, a so-called parallel MIG type having a magnetic film parallel to the magnetic gap G is shown, and the track width is regulated by a track regulating groove having an inclined surface. In addition, FIG.
The present invention is also applicable to MIG type magnetic heads shown in (b) and (c). The magnetic head shown in FIG.
G type, core half 21
The magnetic film 16 is continuous with one of the inclined surfaces 21a formed on the A and 21B. The magnetic head shown in FIG. 2B is of the MIG type in which the magnetic gap G is formed by the magnetic film 16 that is not parallel to the magnetic gap G. FIG.
The magnetic head shown in (c) is a parallel MIG type having a magnetic film 16 only on both sides of the magnetic gap G.

Returning to FIG. 1, the lower core 14 has a magnetic path width (length in the medium sliding direction with respect to the magnetic head 10) of the base 18 made of ferrite in order to shorten the magnetic path and reduce the cross-sectional area. And two pairs of regulating grooves 19 for regulating the thickness (length in a direction orthogonal to the medium sliding direction).
A, 19B, 20A, and 20B are formed. The restriction grooves 19A, 19B, 20A, and 20B will be described in detail in the description of the subsequent steps. Here, when the connection surface with the upper core 12 formed on the lower core 14 to form a magnetic path increases, the resistance component increases due to the lengthening of the thin-film coil having a large specific resistance. Since the inductance due to the increase in the cross-sectional area of the road also increases, it is necessary to keep its area to 0.1 × 0.1 = 1 × 10 ⁻² [mm ² ] or less. On the other hand, if it is too small, the magnetic flux density becomes high, so that the influence of magnetic saturation becomes large. To avoid this effect, the connection area should be 0.0
2 × 0.02 = 4 × 10 ⁻² [mm ² ] or more is required.

The thin-film coil 13 is drawn out of the head 10 by regulating grooves 19 for regulating the magnetic path width of the lower core 14.
A, 19B is provided by providing a lead wire 25 made of a conductive film in the thin film coil 1 at the coil connection points 13A, 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 in a later manufacturing method, but is automatically performed when the thin film coil 10 is formed on the lower core 14,
Extraction of the thin film coil 13 to the outside of the head 10 can be simplified. With this structure, the lead wire 25 of the thin-film coil 13 is guided to the side surface of the lower core 14, so that if the shape of the restriction grooves 19A and 19B is devised, it can be pulled out from a relatively free place.

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

First, as shown in FIG. 3A, the surface of a 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 regulating the magnetic path width of the lower core 14 are inserted in parallel. However, on processing, the regulation grooves 19A and 19B are 1
It is formed as a book groove by grinding.

[0025] Thereafter, as shown in fragmentary cross-sectional view of FIG. _{3 (c), SiO 2,} Cr 2 O 3 on the surface of the plate 30, Ti
An insulating film 31 made of O ₂ or the like is formed by a vacuum film forming technique or the like,
Subsequently, a base film 32 of Cr or the like is formed on the insulating film 31.
To form The base film 32 is formed in order to satisfactorily laminate 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 25 (FIG. 1) of the thin film coil 13 when the head 10 is completed, and has a thickness set so that the resistance value is preferably 1 Ω 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 or TiO ₂ so that the conductive film 33 is not oxidized. In this step, the conductive film 33 is formed by plating because it needs to be about 5 to 10 μm and it is desired to shorten the film forming time.

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 of the projections 30a of the plate 30 whose magnetic path width is regulated. The processing of the groove 35 is performed by grinding. The depth of the groove 35 is desirably 50 μm or less because if it is too deep, the magnetic path is enlarged.

In the next step, as shown in FIG. 3E, a plurality of regulating grooves 20A and 20B for regulating the thickness of the magnetic path are formed in parallel and perpendicular to the regulating grooves 19A and 19B. Form. The restricting grooves 20A and 20B correspond to the restricting grooves 1
Steps are provided for 9A and 19B, and are formed by grinding as a single groove in processing.

When the magnetic gap G has the azimuth angle θ, the regulating 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 regulating grooves 20A, 20B may be formed at an angle of α (= 90 ° −θ) with respect to the regulating grooves 19A, 19B. Note that the magnetic gap G is determined by the azimuth angle θ.
Is formed, the regulating grooves 20A and 20B are formed to be inclined by the azimuth angle θ for the following reason. That is, if the thickness of the core when no magnetic gap G azimuth angle as shown in FIG. 3 (e ₁₎ is T, 3
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 cannot be obtained, or the thin film coil 13 cannot be completely insulated. As described above, when the magnetic gap G has a large azimuth angle, as described above,
If A and 20B are formed at an angle of azimuth angle θ, FIG.
As shown in (e ₃ ), although there is a difference that the joining portions 30b and 30c are formed in a parallelogram shape, the thin film coil 1
3 can be formed to a predetermined core thickness T without cutting.

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

Next, as shown in FIG. 4G, unnecessary glass on the surface of the plate 30 is removed by surface grinding. Thereby, as shown in detail in FIG. 3H, the two magnetic path connecting portions 30b and 30c and the conductive film 33 are exposed.

As shown in FIGS. 4 (h) and 4 (h '), a photoresist (not shown) is applied to the surface of the glass 36' to form the thin film coil 13 (FIG. 1). After exposing the pattern No. 13 (FIG. 4 (h ')), the photoresist portion is removed, and the exposed portion is processed by ion milling to form a spiral coil pattern concave portion 37 on the glass surface. I do. The amount of dent is 4 ~
It is about 5 μm. The pattern of the thin-film coil 13 has a balanced winding shape surrounding the two magnetic path connecting portions 30b and 30c exposed on the surface, and both ends 37a and 37b of the concave portion 37.
Overlap with the exposed portion of the conductive film 33 adjacent to the magnetic path connection portions 30b and 30c. Thereby, when the thin film coil 13 is formed in the concave portion 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 a metal film 38 of excellent conductivity such as Cu or Au is buried 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.
An insulating film 39 made of O ₂ , Cr ₂ O ₃ or the like is formed to a thickness of 1 μm or less by a vacuum film forming technique. 1 μm of insulating film 39
The reason why the magnetic head 10 is formed with a thickness of not more than m is that the magnetic characteristics are not affected when the magnetic head 10 is formed by joining the upper core 12. In the steps up to this point, the pattern of the thin film coil 13 as shown in FIG.
The terminal (lead wire 25) is easily drawn out through the coil connection points 13A and 13B with the terminal 3.

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

Next, a method of processing the upper core 12 is shown in FIG.
This will be described with reference to (a) to (f). The manufacturing method described here basically conforms to the conventional MIG head manufacturing method. However, since only the sliding portion needs to be taken out, the number of ferrite materials having the same size as that of the conventional MIG head increases.

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

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

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

Next, as shown in FIG. 5D, a base film (not shown) serving as 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 or Permalloy is formed. 16 is formed.

Then, as shown in FIG.
_After a gap material (not shown) such as ₂ is formed on the surface, a similarly processed plate 42 ′ is butted against the opposite side, and a butt joint is performed by welding using a glass rod 45.

Thereafter, as shown in FIG. 5 (f), cutting is performed at the locations indicated by broken lines, and blocks 46 of the upper core as indicated by A, B and C are taken out.

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

In the step shown in FIG. 6A, a low-melting 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 heated and bonded. As other joining means, it is also effective to perform resin bonding if the environment resistance is satisfied, or to attach a metal film to both block joining surfaces and join them at low temperature.

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 a 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 configured as described above. According to FIG. 9, the upper core 12 connected via the magnetic path connecting portions 30b and 30c is formed.
It can be seen that the magnetic path 70 formed between the magnetic path 70 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, since the magnetic head 10 is constituted by being divided into an upper core 12 and a lower core 14, a coil formed by a thin film forming method is provided on a joint surface of the lower core 14 with the upper core 12. The connection between the coil and the lead wire is facilitated, and the productivity of the magnetic head having a small magnetic path and excellent C / N characteristics can be improved.

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 is formed on the upper core 12 side. , And 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 terminals of the magnetic head 10 attached to the head base 50 to the printed circuit board 52 are pulled out of Au. The connection is performed by connecting the lead portion (conductive film) 25 exposed on the side surface of the magnetic head 10 and the terminal 52 a on the printed board 52 by wire bonding using a wire or the like.

The magnetic head 10 obtained as described above
Table 1 shows data obtained by comparing the characteristics described above with the MIG type magnetic head described in the conventional example. The mechanical characteristics were as follows: track width was 14 [μm] and gap width was 0.2 [μm].
m], and the gap depth was set to 12 [μm]. Sendust was used for both the magnetic films 16 and 112. Further, the output was measured by using a holding force Hc =
Using a vapor deposition tape of 1600 [Oe], the relative speed of the medium was 10.2 [m / s], and the frequency was 21 [MHz].

[0050]

[Table 1]

In order to make the inductance about 0.45 [μH], the number of turns of the coil can be increased by 6 turns in the configuration of the above embodiment, compared to 14 turns in the conventional magnetic head. Low inductance. Although the direct current (DC) resistance is increased by the use of the thin film coil, there is almost no influence, and the C / N characteristic is 2.
5 [dB] improved. The difference between the results can be evaluated as an effect of reducing the thickness of the winding and reducing the size of the magnetic path of the lower core since the two sliding portions have the same structure.

Next, another embodiment will be described with reference to FIGS.
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 as in the configuration of the embodiment shown in FIG. It is formed in a character shape. With this configuration, it is possible to expose the drawer 25 of the thin-film coil 13 to the bottom surface 14a of the lower core 14.

Further, as shown in FIG. 8B, the thickness of the lead portion 25 of the thin-film coil 13 is increased, and as shown in FIG. By embedding the metal wire 60 or the like having a contact in the glass 36 ′, the terminal can be easily pulled out.

FIG. 9 shows a magnetic path 70 in the configuration of the above embodiment. According to FIG. 9, the magnetic path connecting portion 30b,
It can be seen that the magnetic path 70 formed between 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 leakage magnetic flux shown by 72 may cause an increase in inductance or a decrease in reproduction efficiency, as shown in FIG. 10, a length W formed by joining the core halves 12A and 12B of the upper core 12 is formed. Is substantially the same as the magnetic path width L of the lower core 14. In this case, non-magnetic ceramics 7 are provided at both ends of the core halves 12A and 12B in the direction of medium sliding.
4 is preferably provided by bonding. The ceramic 74 is preferably made of Al ₂ O ₃ , TiO ₂ , Ca—Ti based ceramic, or the like. Although the ceramic 74 is provided in consideration of abrasion, it can be applied to glass.

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

The lower core 14 (base 18) is made of Mn.
-Since it is made of a ferromagnetic oxide magnetic material such as Zn ferrite, the width and the thickness of the magnetic path are regulated by a pair of orthogonal regulating grooves 19A, 19B, 20A, and 20B, so that The size of the road can be reduced. The reason for using ferrite for the base 18 is that there is a degree of freedom in the processing shape and it is suitable for multi-cavity.

The thin-film coil 13 can be easily pulled out 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 connection between the conductive film 33 and the thin-film coil 13 is made, the productivity is excellent. The conventional thin-film head is composed of a lower magnetic film, a thin-film coil, a terminal, an upper magnetic film, and a plurality of layers, and has many steps even if only the thin-film coil forming portion is viewed. Can be formed in one layer because terminal formation is unnecessary, and the productivity is clearly high.

The terminals are connected to the terminals 52a provided on the printed circuit board 52 by using the cross section of the conductive film 33 exposed on the side surface or the bottom surface of the lower core 14. Grooves 19A, 1 for regulating width
If the shape of 9B is devised, the conductive film can be freely drawn.

[0059]

As is apparent from the above description, according to the magnetic head of the present invention, the magnetic head is divided into an upper core and a lower core, and a thin film is formed around a magnetic junction between the lower core and the upper core. Since the coil formed by the forming method is provided, the connection of the lead wire of the coil is facilitated, and the productivity of the magnetic head having a small magnetic path and excellent output-to-noise (C / N) characteristics is improved. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a magnetic head according to the present invention.

FIGS. 2A, 2B, and 2C show examples of a MIG type magnetic gap forming portion applicable to the magnetic head of the present invention.

FIGS. 3A to 3F show a manufacturing process of a lower core of the magnetic head shown in FIG. 1 together with FIGS. 4G to 4K. (E ′) shows a modification of (e), and (e ₁ )
(E ₃ ) are explanatory diagrams thereof.

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

5 (a) to 5 (f) show a process of manufacturing an upper core of the magnetic head shown in FIG.

FIGS. 6A and 6B show a process in which a magnetic head is obtained from an upper core and a lower core.

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

FIGS. 8A to 8C are diagrams showing other embodiments 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 view showing still another embodiment of the magnetic head of the present invention.

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

FIG. 12 is a diagram illustrating 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 Regulatory groove 20A, 20B Regulatory groove 25 Leader

Claims (7)

(57) [Claims] A first core having a magnetic body joined through a magnetic gap; and a second core having a magnetic body, wherein a magnetic force between the first core and the second core is provided. A coil formed by a thin-film forming method is disposed around the joint, and the joint of the second core is formed of a pair of first regulating grooves and a pair of first regulating grooves intersecting with the first regulating grooves. The joint area is regulated by the second groove, and a conductive film is disposed in a portion of the joint portion of the second core regulated by the first regulating groove. A magnetic head connected to a part of a coil. 2. The magnetic head according to claim 1, wherein a part of the conductive film is exposed on a side surface of the magnetic head. 3. The magnetic head according to claim 1, wherein a part of the conductive film is exposed on a bottom surface of the magnetic head. 4. The method according to claim 1, wherein the second core includes:
A magnetic head, wherein a portion removed by the first and second regulating grooves is filled with glass. 5. The magnetic head according to claim 4, wherein the coil is provided on a bonding surface of the glass with the first core. 6. The method according to claim 1, wherein the first core comprises:
A magnetic head, formed by joining two core halves via a gap, wherein there are two joints between the first core and the second core. 7. The magnetic head according to claim 6, wherein one area of the joint is 1 × 10 ⁻² mm ² or less.