JPH1179785A - Thin film magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good adhesion, to make processing easy and to suppress the generation of recesses in an electromagnetic conversion part by constituting a slider of a crystallized glass essentially comprising silicon oxide, magnesium oxide and aluminum oxide in specified proportions and having specified crystallinity, and forming an electromagnetic converting part on the slider. SOLUTION: The crystallized glass for a slider of a magnetic head consists of 30 to 65 wt.% SiO2 , 9 to 40 wt.% MgO, and 8 to 41 wt.% Al2 O3 , and has 30 to 90% crystallization degree and 700 to 800 Vickers' hardness. This crystallized glass has low density as about 3.1 g/cm<3> , which decreases the inertial mass of the slider and enables rapid and accurate seeking operation of a magnetic head. Since the glass material of this compsn. is crystallized at the same time of forming by heating and pressurizing, a planer body can be easily produced. The magnetic head is obtd. by forming an electromagnetic converting part of a thin film laminated body on a slider, and is used for an induction thin film magnetic head or an MR induction composite head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin-film magnetic head having a slider made of crystallized glass.

[0002]

2. Description of the Related Art In recent years, the density of magnetic recording has been increased. Along with this, as a magnetic head for a hard disk, an induction type thin film magnetic head using a soft magnetic thin film as a magnetic pole, and a magnetoresistive effect type magnetic head (MR head) for reproducing using a magnetoresistive effect are actively developed. It is being advanced. The MR head reads an external magnetic signal by a resistance change of a read sensor unit using a magnetic material. The MR head has a feature that a high output can be obtained even in magnetic recording with a high linear recording density because the reproduction output does not depend on the relative speed to the recording medium.
Since the MR head is a reproducing head, an MR induction type composite head in which an induction type head for recording is integrated with the MR head is generally used.

A magnetic head for a hard disk has a slider provided with an electromagnetic transducer on the side surface on the trailing side. The electromagnetic conversion unit of the thin-film magnetic head is formed by sequentially laminating a lower magnetic pole, a gap layer, a coil surrounded by an insulating film, an upper magnetic pole, a protective film, and the like in a predetermined pattern. The slider usually has Al ₂ O ₃ —TiC
A sintered body is used.

[0004] Thin-film magnetic heads are generally used as flying magnetic heads. The floating magnetic head performs recording and reproduction while flying above a magnetic disk that rotates at high speed. The distance between the air bearing surface of the slider (the surface facing the disk) and the magnetic disk is high-density recording. Very narrow to do. Recently, a thin-film magnetic head in which an electromagnetic transducer comes into contact with a magnetic disk has been developed. The flying magnetic head uses CSS
(Contact Start Stop) method is often used. C
In the SS system, the magnetic head is pressed against the disk surface by a spring force while the disk is stationary, and when the disk starts rotating, the magnetic head floats by dynamic pressure.

In a thin film magnetic head, it is desired that the inertial mass of the slider be small in order to increase the seek speed. In addition, the slider must have good wear resistance in order to withstand wear due to repeated CSS. Further, in order to prevent the electromagnetic conversion portion from peeling off from the slider, it is desired that the adhesion between the slider and the electromagnetic conversion portion be good.

However, since Al ₂ O ₃ —TiC sintered body conventionally used as a slider material has a relatively high specific gravity,
Inertia mass cannot be reduced. In order to improve abrasion resistance, when a protective film made of Si is formed on an air bearing surface of a slider as described in, for example, Japanese Patent Application Laid-Open No. 4-276673, Al ₂ O ₃ −
The slider made of the TiC sintered body has insufficient adhesion to the Si protective coating, and thus causes problems such as peeling and insufficient wear resistance. In addition, an insulating layer made of SiO ₂ or the like is usually provided as the lowermost layer of the electromagnetic conversion portion. However, a slider made of Al ₂ O ₃ —TiC sintered body does not have sufficient adhesiveness with this insulating layer. I can't say.

[0007] In general, a thin-film magnetic head first forms an electromagnetic converter on an insulating substrate having a smooth surface.
Next, the insulating substrate is processed into a slider shape by cutting, polishing, or the like, and manufactured. Therefore, the insulating substrate has a smooth surface, or the surface can be easily smoothed, easily cut, and a recess of the electromagnetic conversion portion occurs during polishing after the formation of the electromagnetic conversion portion. Desirably not. However, since the Al ₂ O ₃ —TiC sintered body has a high hardness, it is difficult to process, and a recess of the electromagnetic conversion portion is easily generated.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to have a small inertial mass, a high adhesiveness to an electromagnetic conversion portion, easy processing such as cutting and polishing, easy surface smoothing, An object of the present invention is to provide a thin-film magnetic head having a slider which can suppress the occurrence of recess and has excellent wear resistance.

[0009]

This object is achieved by any one of the following constitutions (1) to (5). (1) It contains silicon oxide, magnesium oxide and aluminum oxide as main components, each of which is SiO 2
_2, in terms of MgO and Al ₂ O _3, when representing the content in weight percent, SiO _2: 30 to 65 wt%, Mg
O: 9 to 40 wt%, Al ₂ O _3: 8~41 weight%, and has a slider composed of crystallized glass crystallization rate is 30 to 90%, the electromagnetic conversion unit on the slider Thin-film magnetic head provided with. (2) The crystallized glass has a Vickers hardness of 600 to 600
800. The thin-film magnetic head of (1) above, (3) The thin film according to the above (1) or (2), wherein the crystallized glass contains titanium oxide, which is converted into TiO ₂ and the content is expressed in terms of percentage by weight, TiO ₂ : 15% by weight or less. Magnetic head. (4) The thin-film magnetic head according to any one of (1) to (3), wherein the crystallized glass contains a diopside crystal. (5) The surface roughness Rmax of the surface of the slider on which the electromagnetic transducer is provided is not more than 5.0 nm (1).
The thin film magnetic head according to any one of (1) to (4).

[0010]

Operation and Effect The thin film magnetic head of the present invention uses the above crystallized glass for the slider. The density of the crystallized glass (about 3.1 g / cm ³ ), which is lower than the density of the Al ₂ O ₃ —TiC sintered body (about 4.2 g / cm ³ ), can reduce the inertial mass of the slider. . Therefore, the seek operation can be performed quickly and accurately.

The above-mentioned crystallized glass is produced by subjecting a glass material having the above composition to heat treatment and crystallization. When the glass material of the above composition is heated from the low temperature side,
Pressure molding utilizing the viscous flow phenomenon is possible at a temperature equal to or higher than the glass transition point and lower than the liquidus temperature. By utilizing the viscous flow of glass, a molded article having a desired shape can be easily obtained in a short time. That is, a plate-like body can be easily obtained by heating and pressing the glass ingot. Moreover, the temperature required for molding is 1
The molding can be performed at a temperature as low as 000 ° C. or less and at a temperature of 900 ° C. or less, and the applied pressure can be as low as about 5 MPa or less. Also, in the method of molding and sintering powder, since there are pores in the molded body, the shrinkage ratio during sintering is large, and it is difficult to obtain good dimensional accuracy. And pressurized to form no pores. Further, in the present invention, since the shape of the contact surface of the press machine used for pressurization reflects on the surface properties of the glass material, a certain degree of smoothness can be obtained only by press molding. For this reason, the polishing step for smoothing the surface performed after crystallization can be simplified. In addition, a smooth surface having a surface roughness (Rmax) of 5.0 nm or less, particularly 4.0 nm or less can be easily obtained by polishing.

The Vickers hardness (600 to 800) of the crystallized glass is lower than the Vickers hardness (about 1800 to 2300) of the Al ₂ O ₃ —TiC sintered body and is close to the hardness of the electromagnetic conversion part. Processing into a slider shape is easy, and recesses in the electromagnetic conversion portion during polishing are less likely to occur. In addition, a protective coating [S
i, TiN, TiCN, diamond-like carbon (DL
C) etc.], peeling hardly occurs.

In the present invention, since a homogeneous bulk glass material is heated and pressed without melting and crystallized at the same time or subsequent to the forming, the slider material is obtained.
A slider having sufficient strength can be obtained. If a part of the glass material is melted during the heat and pressure molding, the structure after crystallization may not be homogeneous and sufficient strength may not be obtained, but the present invention can prevent this. The slider made of the crystallized glass has sufficient wear resistance despite its lower hardness than the Al ₂ O ₃ —TiC sintered body.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thin-film magnetic head according to the present invention has a slider on which an electromagnetic conversion section composed of a thin-film laminate is formed. The present invention is applied to a normal induction type thin film magnetic head and an MR induction type composite head. The MR induction type composite head has an MR head (magnetoresistive head) for reproduction and an induction type head for recording as electromagnetic conversion units. Hereinafter, as an example of a thin-film magnetic head, a configuration of an MR induction type composite head will be described.

FIG. 1 shows an example of the configuration of an MR induction type composite head. This composite head has a structure in which an MR head unit 10 and an inductive head unit 20 are stacked on a slider 1 in this order. The MR head 10 is moved from the slider 11 side.
In this configuration, an insulating film 12, a lower shield film 13, an insulating film 14, an MR film (magnetoresistive film) 15, an MR lead film (electrode film for MR film) 16, and an insulating film 17 are sequentially stacked. The induction type head unit 20 is provided from the MR head unit 10 side.
Lower magnetic pole 21, insulating film 2 acting as a gap between magnetic poles
2, an insulating film 23, a coil 24, an upper magnetic pole 25, and a protective film 26 are sequentially laminated.

Slider In the present invention, the slider 1 is made of crystallized glass obtained by crystallizing a glass material containing silicon oxide, magnesium oxide and aluminum oxide as main components. In the glass material, when silicon oxide is converted to SiO ₂ , magnesium oxide is converted to MgO, and aluminum oxide is converted to Al ₂ O ₃ , and the content is represented by weight percentage,
SiO _2: 30 to 65 wt%, MgO: 9 to 40 wt%, Al ₂ O _3: 8~41 weight%, and preferably Si
O ₂ : 40 to 65% by weight, MgO: 9 to 30% by weight,
Al ₂ O _3: 8~31 by weight.

The glass material having such a composition is made translucent or opaque by crystallization, so that a high strength can be obtained.
_{Since the} hardness is lower than that of ₂ O ₃ —TiC, the workability is excellent and the productivity can be increased. The more detailed reasons for limiting the composition are as follows. If the amount of SiO ₂ is too small, vitrification is difficult, chemical durability is lowered, and high strength cannot be expected. If there is too much SiO ₂ , the working temperature will be high, and it will be difficult for bubbles to escape,
Further, it becomes difficult to ensure the uniformity of the glass. If the content of MgO is too small, the viscosity of the melt becomes high and workability deteriorates,
If the amount of MgO is too large, vitrification becomes difficult, and the chemical durability decreases. Al ₂ O ₃ is excessively and it becomes difficult to deposit uniformly crystals in crystallization small, Al ₂
If the amount of O ₃ is too large, the working temperature will be high, bubbles will not easily escape, and it will be difficult to ensure uniformity of the glass.

In addition to the above main components, the following various subcomponents are added as necessary for improving mechanical strength, adapting the coefficient of thermal expansion to the electromagnetic conversion portion and the mold, and improving fluidity.

Titanium oxide is mentioned as an auxiliary component. Titanium oxide suppresses the progress of crystallization from the glass surface to make it difficult to uniformly crystallize the inside of the glass.
If crystallization from the glass surface precedes, the crystal layer covers the vicinity of the glass surface, and the strength may be impaired. The content of titanium oxide, when expressed by weight percentage in terms of TiO _2, TiO _2: is preferably 15 wt% or less. If the amount of TiO ₂ is too large, when the temperature of the glass material is increased from the glass transition point side, crystallization occurs before showing a sufficient decrease in viscosity necessary for molding. Molding at a relatively low temperature until precipitation becomes difficult.

Further, Ca, Ba, Zn
May be included. Ca and B
a increases the flowability and lowers the working temperature. C
a and Ba have less adverse effects on chemical durability than alkali metal elements. Further, the addition of Ca facilitates the precipitation of diopside crystals, and thus the addition of Ca contributes to the improvement of mechanical strength. Zn is added when it is necessary to increase the coefficient of thermal expansion. When these are converted to CaO, BaO and ZnO, respectively,
+ BaO + ZnO is preferably at most 20% by weight, more preferably at most 15% by weight. If the total content of these components is too large, crystallization tends to proceed from the surface of the glass material.

Noble metal elements as auxiliary components, that is, Pd, Pt, Ag, Au, Re, Ru, Rh and Ir
May be included. By adding these noble metal elements, the strength can be improved and the operation time for crystallization can be shortened, but the cost is increased.
Their total content is preferably 1% by weight or less, more preferably 0.5% by weight or less.

Further, at least one of Mn, Fe, Ni and Ce may be contained as an auxiliary component. When these are converted into MnO, FeO, NiO and CeO ₂ , respectively, MnO + FeO + NiO + CeO ₂ is preferably 2% by weight or less.

Further, at least one of alkali metal elements and P, that is, at least one of Li, Na, K and P may be contained as a subcomponent. The addition of an alkali metal element has the effect of lowering the glass transition point and lowering the working temperature, and also has the effect of adjusting the coefficient of thermal expansion. The addition of P has the effect of adjusting the coefficient of thermal expansion. When these were converted into Li ₂ O, Na ₂ O, K ₂ O and P ₂ O ₅ respectively, Li ₂ O + Na ₂ O + K ₂ O + P ₂ O ₅ was
It is preferably at most 5% by weight, more preferably at most 2% by weight. Most preferably, the alkali metal element and P are not included because they reduce the chemical durability.

Further, B may be contained as an auxiliary component. B is added for adjusting the coefficient of thermal expansion. B to B
When converted to ₂ O ₃ , B ₂ O ₃ is preferably at most 5% by weight, more preferably at most 3% by weight. Most preferably, B is not included because it also lowers chemical durability.

Further, Zr may be contained as an auxiliary component. When converted to Zr to ZrO _2, ZrO ₂ is preferably 5 wt% or less, more preferably 3 wt% or less. If the content of ZrO ₂ is too large, vitrification becomes difficult.

The raw material of the main component is usually an oxide,
Partially, nitride may be used. The auxiliary component may be added as a simple substance or as a compound. Examples of the compound of the accessory component element include oxides, nitrides, chlorides, nitrates, and sulfates. When a nitride is used as a part of the raw material, it is considered that nitrogen atoms are contained in the glass in such a manner as to replace oxygen atoms. The glass material used in the present invention does not contain nitride as short fibers or whiskers. When nitrogen is contained, nitrogen is replaced with Si
When converted to ₃ N _4, Si ₃ N ₄ is preferably 4 wt% or less. If the amount of nitrogen is too large, the hardness will be too high,
In addition, since the composition of nitrogen is likely to fluctuate during production,
The reproducibility of the composition deteriorates.

The glass material has a glass transition point of about 500 to 780 ° C., though it depends on the composition.

The crystal phase contained in the crystallized glass used in the present invention is not particularly limited, but preferably contains at least diopside. The generated crystals vary depending on the composition and may be difficult to identify.In general, the crystals that can be identified among the generated crystals include diopside, magnesium titanate, enstatite,
β-quartz, magnesium alumino titanate, rutile, garnite, sapphireline, petalite and the like.

The average crystal grain size of the crystallized glass is not particularly limited, but is usually 100 μm or less, preferably 10 μm or less.
μm or less, more preferably 1 μm or less. If the crystal grain size is too large, it is difficult to obtain high strength. The crystal grain size can be determined by a scanning electron microscope (SEM) or small-angle X-ray scattering.

The crystallization rate of the crystallized glass is 30 to 9
0%, preferably 60-85%. If the crystallization ratio is too low, the hardness becomes insufficient and the wear resistance becomes insufficient. However, if heat and pressure molding as described below is performed,
Usually, a crystallization ratio of 30% or more is obtained. On the other hand, if the crystallization ratio is too high, excessive crystallization and generation of pinholes in the glass significantly deteriorate the surface properties. Deterioration of surface properties due to excessive crystallization can be corrected by surface polishing, but deterioration of surface properties due to generation of pinholes cannot be recovered. The crystallization ratio in the present specification is a value determined by a peak separation method using an X-ray diffraction chart.

The Vickers hardness (weight: 200 g) of the crystallized glass is preferably from 600 to 800, more preferably from 700 to 800. If the Vickers hardness is too low, the wear resistance becomes insufficient. On the other hand, if the Vickers hardness is too high, it means that the crystallization has progressed too much, and the surface properties deteriorate due to the generation of pinholes.

The electromagnetic conversion unit will be described electromagnetic conversion unit.

The insulating film 12 has a thickness of about 1 to 20 μm,
The constituent material is preferably Al ₂ O ₃ , SiO ₂ or the like, and it is preferable to use a sputtering method or the like for the formation.

The lower shield film 13 has a thickness of 0.1 to 5
μm, constituent materials are FeAlSi, NiFe, CoF
e, CoFeNi, FeN, FeZrN, FeTaN,
CoZrNb, CoZrTa or the like is preferable,
It is preferable to use a sputtering method or a plating method for the formation.

The insulating film 14 preferably has a thickness of about 10 to 200 nm and is made of a material such as Al ₂ O ₃ or SiO ₂ , and is preferably formed by a sputtering method or the like.

The MR film 15 may be composed of a single magnetic film, but is usually preferably a multilayer film structure in which a magnetic film and a non-magnetic film are laminated. As a material of the magnetic film, for example, NiFe, NiFeRh, FeMn, NiMn, C
o, Fe, NiO, NiFeCr and the like are preferable. Also,
As a material of the nonmagnetic film, for example, Ta, Cu, Ag, or the like is preferable. As the multilayer film structure, for example, NiF
eRh / Ta / NiFe three-layer structure, NiFe / Cu
/ NiFe / FeMn, NiFe / Cu / Co / FeM
n, Cu / Co / Cu / NiFe, Fe / Cr, Co /
It is preferable to adopt a structure in which a plurality of units such as Cu and Co / Ag are repeatedly laminated as one unit. Further, in the case of such a multilayer film structure, the thickness of the magnetic film is preferably 0.5 to 50 nm, particularly preferably 1 to 25 nm. The thickness of the non-magnetic film is 0.5 to 50 nm,
In particular, the thickness is preferably 1 to 25 nm. The number of repetitions of the above unit is preferably 1 to 30, especially 1 to 20 times. The thickness of the entire MR film is preferably 5 to 100 nm, particularly preferably 10 to 60 nm. It is preferable to use a sputtering method, a plating method, or the like for forming the MR film.

The MR lead film 16 has a thickness of 10 to 500
nm, especially about 50 to 300 nm, and the constituent material is W, Cu, A
u, Ag, Ta, Mo, CoPt and the like are preferable, and it is preferable to use a sputtering method, a plating method, or the like for the formation.

The insulating film 17 preferably has a thickness of 5 to 500 nm, particularly 10 to 200 nm, and is preferably made of a material such as Al ₂ O ₃ or SiO ₂ , and is preferably formed by a sputtering method or the like.

Each film constituting the MR head portion can be patterned by a usual lift-off method using a resist pattern, a milling patterning method, or a method using both of them.

The lower magnetic pole 21 and the upper magnetic pole 25 of the induction type head 20 are made of a soft magnetic material such as NiFe, CoFe, CoFeNi or the like. The thickness of the lower magnetic pole is 0.
The upper magnetic pole has a thickness of about 3 to 5 μm. In the structure of the illustrated example, the lower magnetic pole 21 also functions as a magnetic shield film for the MR film.
Wider than. The lower magnetic pole may be formed by a plating method, a sputtering method, or the like. It is preferable to use a frame plating method for forming the upper magnetic pole.

The insulating film 22 has a thickness of 0.01 to 0.5 μm
The thickness of the insulating film 23 is about 3 to 20 μm.
6 preferably has a thickness of about 5 to 50 μm. The constituent materials of the insulating film 22 and the protective film 26 are Al ₂ O ₃ , S
It is preferable to use iO ₂ or the like, and it is preferable to use a sputtering method or the like for forming these. Also, the insulating film 23
Is preferably formed by thermally curing a photoresist material.

The coil 24 is made of a conductive material such as Cu. The thickness of the coil is preferably about 2 to 5 μm. It is preferable to use a frame plating method for forming the coil.

The thin-film magnetic head of the present invention is used in combination with a conventionally known assembly such as an arm.

Manufacturing Method Next, a preferred method of manufacturing the thin-film magnetic head of the present invention will be described.

In this method, first, a crystallized glass substrate having a predetermined shape, for example, a disk shape, is manufactured, an electromagnetic conversion section composed of a thin film laminate is formed thereon, and then the substrate is cut or polished to form a substrate. By processing into a slider shape, a thin-film magnetic head is obtained.

FIG. 2 shows an outline of a method for manufacturing a crystallized glass substrate.

The glass material is produced by melting a raw material and quenching it. The melting is performed using a crucible made of platinum, quartz, alumina, or the like, preferably for 5 minutes to 20 hours, more preferably for 10 minutes to 2 hours. The melting temperature varies depending on the composition, but is usually 1400 ° C. or higher. As the raw material, an oxide or a substance capable of forming an oxide when melted, such as a carbonate, a bicarbonate, or a hydroxide, may be used. it can. At the time of heating, a composite oxide is formed by a reaction between the raw materials. Melting is usually performed in air. The quenching method is not particularly limited as long as it can be converted into amorphous glass after cooling. For example, a method of pouring into an iron plate, carbon, water, a mold, or the like can be used.

In order to homogenize the glass, sufficient stirring may be performed at the time of melting, or melting, cooling, pulverization, and re-melting may be repeated, or high-frequency induction heating may be performed.

In order to crystallize the amorphous transparent glass material manufactured in this way, FIGS. 2A and 2B
It is preferable to use any of the methods shown in FIG.

In the method shown in FIG. 2A, a glass material is subjected to a heat treatment for nucleation or phase separation, and then pressure-formed in a temperature range not lower than its glass transition point, and then crystallized.
In FIG. 2A, heat treatment for crystallization is performed after pressure molding, but crystallization may be performed by heating during pressure molding. In FIGS. 2A, 2B and 2C, the heat treatment for nucleation or phase separation is shown as a primary heat treatment, and the heat treatment for crystallization is shown as a secondary heat treatment.

In the method shown in FIG. 2B, a secondary heat treatment is performed after pressure molding without performing a primary heat treatment. Also in this method, crystallization can be performed by heating during pressure molding without performing an independent secondary heat treatment.

In the method shown in FIG. 2C, a primary heat treatment and a secondary heat treatment are sequentially performed after pressure molding.

Of these methods, the method shown in FIG. 2A is most preferable.

Although it is not impossible to form the glass material under pressure after crystallization, it is not preferable because the workability is remarkably deteriorated. However, depending on the composition of the glass material, pressure molding may be relatively easily performed even after crystallization.

In these methods, the primary heat treatment is performed as necessary to uniformly crystallize the glass.
Depending on the composition of the glass material, crystals grow abnormally and the strength becomes insufficient, but in such a case, it is possible to uniformly crystallize by performing a primary heat treatment before crystallization. . Further, by performing the primary heat treatment, the time required for crystallization can be reduced. Various conditions in the primary heat treatment are not particularly limited, but heat treatment may be performed at a temperature near the nucleation or phase separation, specifically, about 600 to 850 ° C. for about 30 minutes to 50 hours. In addition,
When the temperature at which nucleation or phase separation occurs is close to the crystallization temperature, omitting the primary heat treatment has little effect. Also, if the passage time near the temperature at which nucleation or phase separation occurs is lengthened by slowing the rate of temperature rise during the secondary heat treatment,
The same effect as in the case where independent primary heat treatment is performed can be obtained.

The temperature at the time of pressure molding in each of the methods shown in FIGS. 2A to 2C is set to be equal to or higher than the glass transition point of the glass material so that viscous flow of the glass can be utilized.
It is a temperature range where molding is possible at MPa or less. Since the crystallization of the glass material proceeds during the molding depending on the temperature during the molding, the temperature during the molding is appropriately set so as to fall within a desired crystallization rate range. This temperature varies depending on the time required for molding, and may be specifically confirmed by experiments or the like.
Usually, it is 1000 ° C or lower, preferably 700 to 930 ° C.

The heating of the glass material may be carried out by inserting it into a preheated mold, or by placing the mold containing the glass material in a furnace. Then, after the temperature of the glass material is raised to the softening point, pressure molding is performed.
In addition, the mold may be taken out of the furnace after heating and pressurized. In this case, since a large number of glass materials can be heated simultaneously in the furnace, the productivity is improved. Thus, the pressing of the glass material may be started before reaching the maximum temperature during molding, or may be started after reaching the maximum temperature during molding.
In the former case, the molding is started simultaneously with the softening of the glass, so that the molding step can be shortened. Further, if the necessary displacement is obtained before reaching the set maximum temperature, pressurization can be stopped at that point, so that the time can be further reduced. On the other hand, in the latter, the homogeneity after molding is good. In addition, since pressure is applied after the viscosity of the glass has decreased, cracking of the molding die can be prevented. Pressurization is
It only has to last until the glass material shows a deformation faithful to the mold,
Although it varies depending on the pressurizing means and the temperature at the time of pressurization, it is usually sufficient to keep it for about 5 to 20 minutes.

When crystallization proceeds from near the surface of the glass material, there may be a region having a high crystallization rate near the surface of the glass material after crystallization. Although the present invention includes the case where such a region exists, it is more preferable that the region is uniformly crystallized and such a region does not substantially exist.

In the case where the secondary heat treatment is performed after the pressure molding, the productivity is improved by performing the secondary heat treatment without cooling.

The glass transition point, softening point, crystallization temperature, temperature at which nucleation or phase separation occurs, and the like can be determined by differential thermal analysis, measurement of the coefficient of thermal expansion, and the like.

It is preferable that the surface of the crystallized glass substrate is polished and smoothed before forming the electromagnetic conversion portion. The polishing method is not particularly limited, and may be appropriately selected from methods capable of achieving the required surface roughness. The surface roughness after polishing (Rmax specified in JIS B 0610) is 5.
It is preferably at most 0 nm, particularly preferably at most 4.0 nm.

[0062]

Embodiments of the present invention will be described below.

Substrate No. 1 The final composition was SiO ₂ : 50.0% by weight, MgO: 1
5.1 wt%, Al ₂ O _3: 11.0 wt%, TiO _2:
The compound powder was weighed so as to be 12.2% by weight and CaO 2: 11.7% by weight, and a homogeneous glass melt was prepared by a re-melting method, and the glass melt was poured into a carbon mold. A dome-shaped glass ingot was obtained.

The glass ingot is placed in an electric furnace and subjected to a first heat treatment and a second heat treatment. During the second heat treatment, the glass ingot is subjected to pressure molding to form a disc-shaped substrate N made of crystallized glass.
o.1. The first heat treatment is for annealing and crystal nucleation for relaxing the ingot, and the second heat treatment is for crystallization. The temperature-time profile of the primary heat treatment is as follows: the temperature is raised to 750 ° C. in 35 minutes, held for 5 minutes for annealing, and then lowered to 730 ° C. in 5 minutes.
After holding for a time, the temperature was lowered to 20 ° C. in 35 minutes. The temperature-time profile of the secondary heat treatment is 850.
After raising the temperature to 40 ° C. for 40 minutes and holding for 30 minutes, 910
To 10 ° C. in 10 minutes and hold for 10 minutes, then 2
The temperature was lowered to 20 ° C. over time. In addition, pressurization is
It is performed at 760-850 ° C, and the pressing force is 0.28MPa.
And Each heat treatment was performed in an Ar atmosphere to prevent oxidation of the carbon mold. Substrate No. 1 was white and translucent.

Next, the surface of the substrate No. 1 was polished. For polishing, a fixed abrasive platen with a pressure set to 300 g / cm ² was used, and the working fluid was prepared by diluting the grinding fluid 50-fold (p
H9) was used. This polishing reduced the surface roughness Rmax to 4.0 nm or less.

From the X-ray diffraction chart of the substrate No. 1, the crystallization ratio was determined by the peak separation method and found to be 35%. Vickers hardness of substrate No.1 (weight 200g)
Was 660.

TMA (Thermo-mechanical analysis) for substrate No. 1
When the thermal expansion characteristic was examined, the rate of change of the linear expansion coefficient was small and stable in the heating range (300 ° C. or lower) in the processing step of the thin-film magnetic head. Also, the dimensional change was negligible.

In the temperature-time profile of the substrate No. 2 secondary heat treatment,
Substrate No. 2 was manufactured under the same conditions as in the case of Substrate No. 1 except that the holding time at ° C. was 2 hours and the holding time at 910 ° C. was 30 minutes. Substrate No. 2 was white and opaque.

The surface of substrate No. 2 was polished in the same manner as substrate No. 1. By this polishing, the surface roughness Rmax was 4.0n.
m or less.

The same measurement as that of the substrate No. 1 was performed on the substrate No. 2, and as a result, the crystallization ratio was 80% and the Vickers hardness was 770. In addition, the stability of the coefficient of linear expansion at a high temperature of the substrate No. 2 was better than that of the substrate No. 1.

Substrate No. 3 (Comparative Example) A glass ingot having a composition that is easier to crystallize than those used for substrates Nos. 1 and 2, specifically, SiO ₂ : 43.0
% By weight, MgO: 23.9% by weight, Al ₂ O ₃ : 15.
7 wt%, TiO _2: 10.5 wt%, CaO:
910% by weight of a glass ingot consisting of 6.9% by weight.
Substrate No. 3 was produced under the same conditions as in the case of Substrate No. 2 except that the holding time at ° C. was 4 hours. Substrate No. 3 was white and opaque.

The surface of the substrate No. 3 was polished in the same manner as the substrate No. 1. By this polishing, the surface roughness Rmax is 32 nm
It became. When the surface of the substrate No. 3 was observed with an optical microscope, many pinholes were observed even after polishing, and it was impossible to use the slider as a slider.

The same measurement as that of the substrate No. 1 was performed on the substrate No. 3, and as a result, the crystallization ratio was 95% and the Vickers hardness was 790.

When the glass ingot used for producing the substrate No. 3 was subjected to the secondary heat treatment used for producing the substrate No. 1 or the substrate No. 2, the crystallization ratio and the Vickers hardness were within the range of the present invention. Became inside.

After forming an electromagnetic conversion portion on the surface of the thin film magnetic head substrate No. 1 or No. 2, the substrate is processed into a slider shape by cutting and polishing to produce a thin film magnetic head having the structure shown in FIG. did. The insulating film 12 in contact with the slider 1 was made of SiO ₂ .

Regardless of which substrate was used, cutting and polishing of the substrate was easy, and a thin-film magnetic head was obtained in a short time. In addition, no recess of the electromagnetic conversion portion occurred during polishing.

Using these thin-film magnetic heads, CSS
Was repeated. As a result, it was confirmed that reading was possible even when CSS was repeated 100,000 times or more, that the adhesion between the slider and the electromagnetic conversion portion was good, and that the slider had good wear resistance.

From the above results, the effect of the present invention is clear.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration example of a thin-film magnetic head.

FIGS. 2A to 2C are flowcharts for explaining a method for producing crystallized glass used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slider 10 MR head part 12 Insulating film 13 Lower shield film 14 Insulating film 15 MR film (Magnetoresistance effect film) 16 MR lead film 17 Insulating film 20 Inductive head part 21 Lower magnetic pole 22 Insulating film (gap) 23 Insulating film 24 Coil 25 Upper magnetic pole 26 Protective film

Claims (5)

[Claims] 1. A silicon oxide comprises as a main component magnesium oxide and aluminum oxide, which was converted into SiO _2, MgO and Al ₂ O _3, respectively, when representing the content in weight percent, SiO _2:. 30 to 65 wt%, MgO: 9 to 40 wt%, Al ₂ O _3: 8~41 weight%, and the crystallization rate has a slider composed of crystallized glass is 30 to 90%, on the slider Thin-film magnetic head provided with an electromagnetic converter. 2. The crystallized glass having a Vickers hardness of 6
2. The thin-film magnetic head according to claim 1, wherein the number is from 00 to 800. 3. The crystallized glass comprises titanium oxide,
3. The thin-film magnetic head according to claim 1, wherein TiO _{2 is} 15% by weight or less when converted to TiO ₂ and expressed as a percentage by weight. 4. The thin-film magnetic head according to claim 1, wherein said crystallized glass includes a diopside crystal. 5. The thin-film magnetic head according to claim 1, wherein a surface roughness Rmax of a surface of the slider on which the electromagnetic transducer is provided is 5.0 nm or less.