KR100282214B1 - Magnet head and method for manufacturing the same - Google Patents

Abstract

The present invention improves precision by using a gap material having a structure in which a Cr ₂ O ₃ layer 8 is sandwiched between a nonmagnetic oxide layer 7 containing SiO ₂ as a main component between the magnetic metal films 1. A MIG type magnetic head having a magnetic gap 6 is provided. When silicate glass such as borosilicate glass is used for the nonmagnetic oxide layer, uneven wear of the gap material is suppressed. In addition, when heating of the low melting glass 4 (glass transition point Tg) which joins the core half body 2 is performed in the atmosphere containing oxygen in the temperature range of Tg-85 degreeC <= T <= Tg-35 degreeC at least, The flowability of the low melting glass is improved.

Description

Magnetic head and method for manufacturing the same

The present invention relates to a magnetic head and a method of manufacturing the same. More specifically, the present invention provides a metal in gap (MIG) suitable for high-density recording and reproducing information on a high-magnetism magnetic recording medium used in a system such as a digital VTR or data streamer. It relates to a type magnetic head and a manufacturing method thereof.

High density is required for magnetic recording systems such as VTRs and data streamers. Therefore, as a magnetic head suitable for high-density magnetic recording reproduction, magnetic heads using metal magnetic materials such as Co-based amorphous films or Fe-based nitride films having a higher saturation magnetic flux density (Bs) than ferrite materials, in particular, MIG-type heads are developed. This is being actively done.

In the MIG type head, as shown in Fig. 12, a metal magnetic layer 21 having a high saturation magnetic flux density is formed on a core half body 22 made of ferrite, which is a magnetic core, and a magnetic gap 26 between the metal magnetic layers 21 is formed. ) Has a structure installed. Conventionally, the gap material existing in the magnetic gap 26 has a structure in which the metal Cr layer 28 is sandwiched by the SiO ₂ layer 27 as shown in Fig. 13, which is an enlarged view of the sliding surface 25 of the MIG head. Had The core half body 22 is joined by lead glass 24 which is low melting point glass.

A conventional manufacturing method of the MIG head is described based on Figs. 14 (a) to (f). First, the winding groove 32 and the white glass groove 33 are formed in the ferrite core 31 (Figs. 14 (a) and (b)). Next, the track groove 34 is formed in the core 31, and the gap facing surface 35 is polished (Fig. 14 (c)). Further, in the region including the gap facing surface 35 of the core 31, the magnetic metal layer 21, the SiO ₂ layer 27, and the Cr layer 28 are formed in this order by, for example, a sputtering method ( Fig. 14 (d)). In this way, a pair of core half body which formed the gap material is abutted so that a gap surface may oppose, and the lead glass 24 is mounted in a groove part (FIG. 14 (e)). Further, the lead glass 24 is moulded on the Cr layer 28 by heat treatment to bond the cores to the gaps to produce one gap bar (Fig. 14 (f)). Heat treatment for joining the core half is performed in nitrogen gas (N ₂ ) to prevent oxidation of the magnetic metal layer 21. After this step, the cap bar is cut at a predetermined head chip core width and azimuth angle, and the sliding surface is polished to complete the head chip.

By the way, the MIG head of the conventional structure has a problem that the precision of a magnetic gap length is not enough, and a characteristic is not stabilized. As a result of analyzing the cause of the present invention, as shown in Fig. 15, the conventional gap material is partially and non-uniformly oxidized by residual oxygen during the heat treatment or oxygen in the low melting lead glass 24 as shown in FIG. It has been found that the oxide 29 expands in volume. Since the incomplete oxide 29 has a nonuniform film thickness, a magnetic gap 26 of stable length cannot be obtained.

Metal Cr is used as a gap material to improve the wettability of the lead glass 24. If only SiO ₂ layer is used without using Cr, as shown in Fig. 16, the flowability of the lead glass 24 worsens, and the strength of the head chip cannot be obtained sufficiently.

An object of the present invention is to provide a MIG type magnetic head having a magnetic gap with improved accuracy while securing the strength of the head chip. Moreover, an object of this invention is to provide the manufacturing method of such a MIG type magnetic head.

1 is a perspective view of a MIG type magnetic head of the present invention;

Fig. 2 is a diagram showing the magnetic gap vicinity of the sliding surface of the MIG type magnetic head of the present invention;

3 (a) to 3 (f) show a method of manufacturing the MIG magnetic head of the present invention;

4 is a diagram showing the change in layer thickness after heat treatment of Cr and Cr ₂ O ₃ ;

5 is a diagram showing a wear state of a gap material having a configuration of Cr ₂ O ₃ / SiO ₂ ;

Fig. 6 is a diagram showing the wear state of a gap material having a configuration of Cr ₂ O ₃ / borosilicate glass;

7 shows heat treatment conditions;

FIG. 8 shows the wetting angle of lead glass on Cr and Cr ₂ O ₃ under the heat treatment conditions shown in FIG.

9 is a diagram showing a distribution of a gap length of a magnetic head having a gap material of conventional Cr / SiO ₂ ;

10 is a diagram showing a distribution of a gap length of a magnetic head having a gap material of Cr ₂ O ₃ / borosilicate glass;

11 is a diagram showing the vicinity of a magnetic gap of the sliding surface of another MIG type magnetic head of the present invention;

12 is a perspective view of a conventional MIG type magnetic head;

Fig. 13 is a diagram showing the vicinity of the magnetic gap of the sliding surface of the conventional MIG type magnetic head;

14 (a) to 14 (f) show a manufacturing method of a conventional MIG magnetic head;

Fig. 15 is a diagram showing the magnetic gap vicinity of the sliding surface of a conventional MIG type magnetic head having an incompletely and non-uniformly oxidized Cr layer.

Fig. 16 is a perspective view showing a MIG type magnetic head in a state in which bonding by glass is not sufficient.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described with reference to drawings. However, the following embodiments do not limit the invention.

In one embodiment of the MIG head of the present invention shown in Fig. 1, the core half body 2 made of ferrite, which is a magnetic core, is joined by lead glass 4, which is low melting point glass, as in the conventional MIG head. The core half body 2 is formed with a gap facing surface for constituting the magnetic gap 6 and a groove portion for the lead glass 4 to which the core half bodies are bonded together. In the core half body 2, a magnetic metal layer 1, a borosilicate glass layer 7, and a Cr ₂ O ₃ layer 8, such as a FeTaN layer having a high saturation magnetic flux density, are formed in this order. The laminated film is formed to cover at least the gap facing surface and the groove portion formed in the vicinity thereof.

As shown in FIG. 2, which is an enlarged view of the sliding surface of the MIG head of FIG. 1, in this MIG head, a Cr ₂ O ₃ layer 8 is used in place of the Cr layer. Borosilicate glass layer 7 and the Cr ₂ O ₃ layer 8, a gap material for forming the magnetic gap 6 is formed in the core half bodies (2) are in contact with each, and as a result, a borosilicate glass layer 7, the Cr ₂ O ₃ layer has a structure in which the nip (8).

As shown in Fig. 3, this MIG head has a borosilicate glass layer 7 instead of a SiO ₂ layer 27, and a Cr ₂ O ₃ layer 8 is used in place of the Cr layer 28. Except for the above, it can be manufactured in basically the same order as the conventional manufacturing method shown in FIG. However, in order to improve the fluidity | liquidity of the glass 4 which bonds a core half body, it is preferable to employ | adopt the heat processing conditions mentioned later.

In order to determine the layer thickness change by the heat treatment of the Cr layer and the Cr ₂ O ₃ layer, and subjected to a heat treatment in an electric furnace of yangcheung for use in the production of the MIG type head. As a result, as shown in Fig. 4, for example, the Cr layer showed an increase in thickness of about 70% by heat treatment at 520 캜 for 10 minutes, but the Cr ₂ O ₃ layer hardly exhibited a film thickness. It became. Cr becomes Cr oxide and expands, but since Cr ₂ O ₃ oxidizes from the beginning, its volume is almost constant. Also in these results, it was found that by using the Cr ₂ O ₃ layer for the magnetic gap of the MIG head, there is no change in film thickness due to heat treatment and a stable gap length can be realized.

As described above, the MIG head of the present invention uses a Cr ₂ O ₃ layer instead of the Cr layer, but other materials are not limited to those used in the above embodiment. For example, the core half is not limited to ferrite, and other ferromagnetic oxides may be used. In a pair of core halves, at least one core half may form a magnetic core with ferromagnetic oxide. Moreover, although the lead glass which bonds a core half body is not limited to this, Preferably it becomes low melting glass of 500 degrees C or less softening point. FeTaN is exemplified as the metal magnetic layer, but a metal magnetic layer such as Co-based amorphous, sendust (Fe-Si-Al), or FeGaSiRu may be used. In addition, the borosilicate glass layer is also not limited to be any non-oxide layer comprising mainly SiO _2. A non-magnetic oxide layer, as it is preferable that the SiO _2, such as for example SiO ₂ glass layer, alumino-silicate glass layer, soda lime silicate glass layer using glass as a skeleton component.

In consideration of wear of the gap material, it is preferable to use silicate glass for the nonmagnetic oxide layer. This is because the hardness of the entire gap material is prevented from being excessive by using Cr ₂ O _3, which is higher in hardness than Cr. If the hardness of the entire gap material becomes too large, uneven wear occurs when a metal tape such as a metal vapor deposition (ME) tape is run for a long time. As illustrated in FIG. 5, when the gap material is composed of the Cr ₂ O ₃ layer 8 and the SiO ₂ layer 9, uneven wear occurs in the gap material protruding from the magnetic layer, and the head output tends to decrease. However, if, for example, a borosilicate glass layer 7 having a relatively low hardness is used in place of the SiO ₂ layer 9, uneven wear is eliminated as shown in Fig. 6, and stable running of the metal tape 10 is achieved. Status and stable head output can be obtained.

Next, preferable heat treatment conditions of the manufacturing process of the MIG head of this invention are demonstrated. The fluidity of low melting glass, such as lead glass, on Cr ₂ O ₃ is better than, for example, a borosilicate glass phase, but decreases compared to a Cr phase that has been used in the past. The decrease in the fluidity of the low melting point glass is not preferable from the viewpoint of sufficiently maintaining the gap strength of the MIG head. Here, by introducing an atmosphere containing oxygen (for example, air) in the heat treatment process, it is preferable to improve the wettability of the glass to flow. The purpose of improving the wettability of the glass on the Cr ₂ O ₃ layer is achieved by introducing an atmosphere containing oxygen up to a temperature which is a temperature rising process during heat treatment. Here, as shown in Fig. 7, in the temperature raising process of the heat treatment (holding for 10 minutes at the maximum temperature of 510 DEG C), the heat treatment is performed in the atmosphere up to a certain temperature Tc afterwards in a nitrogen (N) flow. The relationship between the contact angle of lead glass (glass transition point Tg = 385 ° C.) on the Cr layer or the Cr ₂ O ₃ layer and the atmospheric substitution temperature (Tc) for replacing the atmosphere with nitrogen was investigated.

As a result, as shown in FIG. 8, the contact angle on the Cr ₂ O ₃ layer is inferior to the contact angle on the Cr layer when Tc is about 200 to 300 ° C. However, when Tc is 350 ° C or more, even on the Cr ₂ O ₃ layer. It was confirmed that the wettability almost equivalent to that of the Cr layer could be realized. Therefore, in consideration of the actual heat treatment, the heat treatment is preferably performed in an oxygen-containing atmosphere such as air at least at 300 to 350 ° C during the temperature increase process. This temperature differs depending on the glass transition point (Tg) of the low melting glass used. When expressed by Tg, preferable temperature is generally (glass transition point Tg-85 degreeC)-(glass transition point Tg-35 degreeC). In addition, the same experiment was conducted using a SiO ₂ layer or a borosilicate glass layer in place of the Cr ₂ O ₃ layer. However, even when Tc was raised to 510 ° C., the wettability same as the Cr layer could not be realized.

<Example>

Hereinafter, the present invention will be described in more detail by way of non-limiting examples.

Example 1

A MIG head having the structure shown in FIGS. 1 and 2 was manufactured according to the process shown in FIG. Specifically, Mn-Zn ferrite was used as the core half body 2 and a FeTaN layer having a saturation magnetic flux density Bs = 1.6T as the magnetic metal layer 1. In addition, a nonmagnetic oxide was made into borosilicate glass, and the glass used for core bonding was made into lead glass of glass transition point Tg = 385 degreeC. In addition, each of the thin film containing the borosilicate glass layer and the Cr ₂ O ₃ layer was formed by sputtering. In this embodiment, the thickness of the Cr ₂ O ₃ layer is 30㎚, borosilicate glass has a thickness 50㎚.

In order to mold the lead glass 4, in the heat treatment process, the atmospheric substitution temperature Tc was 350 degreeC according to the temperature raising and lowering process as shown in FIG. That is, it heat-treated in air | atmosphere until after the temperature rising process 350 degreeC in nitrogen flow after that.

On the other hand, for comparison, a magnetic head having a gap material of the conventional Cr / SiO ₂ configuration is also produced, and the heat treatment is performed together with the magnetic head according to the present embodiment having the gap material of the Cr ₂ O ₃ / borosilicate glass configuration. The later gap length was measured.

FIG. 9 shows the distribution of the gap length of the gap material of the magnetic head of the conventional type, and FIG. 10 shows the distribution of the gap length of the gap material of the magnetic head of this embodiment. As shown in Fig. 9 and Fig. 10, the deviation (standard deviation 0.01 m) of the gap material of the present embodiment is smaller than that of the conventional gap material (standard deviation 0.03 m).

In addition, in the magnetic head of the present embodiment, it was possible to realize a good magnetic gap without oxidation of the surface of the magnetic metal layer by heat treatment. Even if this magnetic head was made to run on metal tapes, such as metal deposition (ME) tape, for a long time, the gap material did not protrude from the magnetic metal layer, and it was possible to maintain stable head output.

Thus, the MIG type head which the precision of a gap length improved and the head characteristic was stabilized was able to be manufactured. As shown in the above embodiment, according to the present invention, the production yield at the time of industrially producing the MIG head can be improved.

Example 2

The Cr ₂ O ₃ layer and changing the thickness of the borosilicate glass layer the same as in Example 1 was used to prepare the MIG type head. In addition, the thickness of the gap material which consists of said two layers was made into 80 nm in total in any case. With respect to the obtained magnetic head, the film oxidation state of the magnetic metal layer of the magnetic head, the presence or absence of projections of the gap material when the ME tape was run, and the wettability of the lead glass were examined. The results are shown in Table 1.

thickness Cr ₂ O ₃ 0 10 20 30 40 50 60 70 80 Borosilicate glass 80 70 60 50 40 30 20 10 0 characteristic Membrane oxidation A A A A A A B B B Gap projection A A A A A A A A A Glass flow B A A A A A A A A

Here, the unit is nm.

In addition, instead of the structure of the Cr ₂ O ₃ / borosilicate glass, the magnetic head having the structure of Cr ₂ O ₃ / SiO ₂ is similarly formed with a Cr ₂ O ₃ layer and a SiO ₂ layer with an entire gap length of 80 nm. Made by changing the thickness of. This magnetic head was also evaluated for characteristics as described above. The results are shown in Table 2.

thickness Cr ₂ O ₃ 0 10 20 30 40 50 60 70 80 SiO ₂ 80 70 60 50 40 30 20 10 0 characteristic Membrane oxidation A A A A A A B B B Gap projection B B B B B B A A A Glass flow B A A A A A A A A

Here, the unit is nm.

However, in Table 1 and Table 2, the state in which the magnetic metal layer is not oxidized, the gap projection is less than 10 nm, and the state in which lead glass flows satisfactorily is represented as A, and otherwise, B is indicated.

In Table 1 and Table 2, when the thickness of the borosilicate glass layer or SiO ₂ layer is 20 nm or less, it can be seen that film oxidation of the magnetic metal layer occurs. Therefore, it is preferable that the thickness of nonmagnetic oxide layers, such as a borosilicate glass layer, shall be 30 nm or more. In addition, it was confirmed that the projection of the gap material after long time use was controlled by employing a borosilicate glass layer instead of a high SiO ₂ layer as the nonmagnetic oxide layer.

In this embodiment, the thickness of the gap material is 80 nm, and the thickness of the nonmagnetic oxide is changed within this range. The MIG head of the present invention can be applied to, for example, a head having a gap length of about 2 μm. have. Therefore, the upper limit of the thickness of a nonmagnetic oxide layer is not specifically limited, For example, when it applies to the magnetic head whose gap length is 2 micrometers, it is less than 2 micrometers.

Example 3

A MIG head was produced in the same manner as in Example 1 except that discharge machining was used. As shown in Fig. 11, this MIG type head is characterized in that the track width is regulated by electric discharge machining. Specifically, in the process shown in Fig. 3 (e), first, low melting lead glass is molded into a back groove, discharge processing of track regulation is performed, and then low melting lead glass is molded into the track groove. The manufacturing method is different. In such a MIG type head, a high-precision magnetic gap could be realized in the same manner as in Example 1 by using a gap material having a structure in which a Cr ₂ O ₃ layer was sandwiched by a borosilicate glass layer.

According to the present invention, there is provided a MIG type magnetic head having a gap material sandwiching a Cr ₂ O ₃ layer in a magnetic gap with a nonmagnetic oxide layer composed mainly of SiO ₂ .

According to the MIG type magnetic head using a Cr ₂ O ₃ layer instead of a Cr layer, the magnetic gap length caused by partial and uniform oxidation of the gap material while ensuring glass flowability of lead glass or the like used in the magnetic head manufacturing process is obtained. The deterioration of precision can be suppressed. There is also an advantage in that the gap length can be measured accurately. This is because the reflection of light does not become a problem as in the case of using a Cr layer because the Cr ₂ O ₃ layer is substantially transparent. Improvement of the gap length precision and measurement accuracy greatly improves the manufacturing yield of the magnetic head.

According to the present invention, there is also provided a process of forming a nonmagnetic oxide layer and a Cr ₂ O ₃ layer containing, as a main component, a metal magnetic layer and SiO ₂ in a pair of core halves, and the pair of core halves _Of a MIG-type magnetic head comprising a step of forming a gap material in which the nonmagnetic oxide layer sandwiches the Cr ₂ O ₃ layer, wherein the non-magnetic oxide layer is bonded by a softened glass so that at least a part of the ₂ O ₃ layer is in contact. A manufacturing method is provided.

In this manufacturing method, it is preferable to heat and soften the said glass in oxygen containing at least in the following temperature range.

Tg-85 ℃ ≤ T ≤ Tg-35 ℃

However, Tg is the glass transition point of the said glass. According to this preferred manufacturing method, the flowability of the glass is improved.

A non-magnetic oxide layer mainly composed of the SiO ₂ is preferably a layer silicate glass, in particular borosilicate glass layer. This is because uneven wear of the gap material is less likely to occur than when SiO ₂ glass is used, and stable head output can be obtained.

In addition, a non-magnetic oxide layer mainly composed of the SiO ₂ preferably has a thickness of more than 30㎚. This is because oxidation of the magnetic metal layer can be suppressed.

Moreover, it is preferable that the said glass which bonds a core half body is low melting glass which has a softening point of 500 degrees C or less, and it is preferable that it is glass which has PbO as a main component specifically ,.

Claims (14)

A MIG type magnetic head characterized in that a nonmagnetic oxide layer containing SiO ₂ as a main component has a gap material sandwiching a Cr ₂ O ₃ layer in a magnetic gap. The MIG type magnetic head according to claim 1, wherein the nonmagnetic oxide layer containing SiO ₂ as a main component is a silicate glass layer. The MIG type magnetic head according to claim 2, wherein the silicic acid glass layer is a borosilicate glass layer. The MIG type magnetic head according to claim 1, wherein the nonmagnetic oxide layer containing SiO ₂ as a main component has a thickness of 30 nm or more. The method according to claim 1, wherein at least a part of the Cr ₂ O ₃ layer abuts a pair of core halves formed of a metal magnetic layer, a nonmagnetic oxide layer mainly composed of SiO ₂ , and a Cr ₂ O ₃ layer in this order. MIG type magnetic head obtained by bonding by heating and softening the glass. The MIG type magnetic head according to claim 5, wherein the glass to which the core half is joined has a softening point of 500 ° C or lower. The MIG type magnetic head according to claim 5, wherein the glass for joining the core half has PbO as a main component. Forming a metal magnetic layer, a nonmagnetic oxide layer mainly composed of SiO ₂ , and a Cr ₂ O ₃ layer in this order on the pair of core halves, and forming the pair of core halves at least a portion of the Cr ₂ O ₃ layer And a step of forming a gap material in which the nonmagnetic oxide layer sandwiches the Cr ₂ O ₃ layer so that the non-magnetic oxide layer is bonded by a glass softened by heating so as to abut. The method of manufacturing a MIG type magnetic head according to claim 8, wherein the glass is softened by heating in an atmosphere containing oxygen at least in the following temperature range. Tg-85 ℃ ≤ T ≤ Tg-35 ℃ However, Tg is the glass transition point of the said glass. The method of manufacturing a MIG type magnetic head according to claim 8, wherein the nonmagnetic oxide layer containing SiO ₂ as a main component is a silicate glass layer. The method of manufacturing a MIG type magnetic head according to claim 10, wherein the silicate glass layer is a borosilicate glass layer. The method of manufacturing a MIG type magnetic head according to claim 8, wherein the nonmagnetic oxide layer containing SiO ₂ as a main component has a thickness of 30 nm or more. The method of manufacturing a MIG type magnetic head according to claim 8, wherein the glass for joining the core halves has a softening point of 500 ° C or lower. The method for manufacturing a MIG type magnetic head according to claim 8, wherein the glass for joining the core half has PbO as a main component.