JPS61236011A - Composite substrate for thin film magnetic head - Google Patents

Abstract

PURPOSE:To produce easily a laminated thin film magnetic head by laminating and forming a specified nonmagnetic oxide ceramic sheet between 2 soft ferrite sheets through a glass adhesive layer and specifying the outer principal plane of the soft ferrite sheet. CONSTITUTION:A nonmagnetic oxide ceramic sheet 3 having a thermal expansion coefficient which differs from thermal expansion coefficient of a soft ferrite sheet by <=1X10<-6>/deg is laminated and formed between the 2 soft ferrite sheets 1 and 2 through a glass adhesive layer 4 and the surface roughness of the outer principal plane of each soft ferrite is regulated to <=200Angstrom . In the composite substrate, 2 layers of soft ferrite are electrically separated since the ceramic layer and the glass layer used mainly of or laminating and sticking are provided between the soft ferrite layers and a magnetic circuit can be respectively formed on the soft ferrite layer surfaces of both principal planes of the substrate. Besides, the glass layer 4 is coated, laminated and pressed on both principal planes of the ceramic sheet 3 and the material on which the glass layer is coated and the principal plane are appropriately selected in accordance with the operability and the material of each layer. A bulk-type thin film magnetic head can be thus manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to a composite substrate for a thin film magnetic head used in a magnetic disk device, etc., and in particular, to magnetic recording.

The present invention relates to a composite substrate for a thin film magnetic head on which read and erase heads can be stacked.

Background Art In general, thin-film magnetic heads have excellent frequency characteristics and are manufactured using a manufacturing process based on semiconductor technology, making it possible to manufacture high-precision magnetic heads at low cost, and they will become the mainstream of magnetic heads in the future. considered to be a thing.

Thin film magnetic heads include inductive heads used as recording and reproducing heads and magnetoresistive heads used as reproducing heads.

As shown in FIG. 4, the inductive head includes a lower core (20) made of a substrate such as soft ferrite, and a permalloy core (20) disposed on the lower core (20) through a gap.

Upper core made of sendust or amorphous (
21), a conductor (23) such as copper disposed within the insulating layer (22) in the upper core (21), and 7! on the outside of the upper core. !
! It consists of two overlapping protective film layers (24).

As shown in FIG. 5, the magnetoresistive element head includes a substrate (25) serving as a magnetic shield material, a magnetoresistive element (26) made of permalloy disposed with a predetermined gap in between, and a magnetoresistive element (26) made of permalloy placed on both sides of the element (26). The yoke material (21) disposed in the protective film layer (28) is built into the protective film layer (28).

Recording heads, such as tunnel-type, straddle-type, and bulk-type magnetic heads for floppy disks.

In order to create a configuration in which a read head is combined, it is conceivable to make the thin film magnetic head a two-layer structure, but after creating the first layer thin film magnetic head, the second layer thin film magnetic head is directly attached. When configured, depending on the core shape of the first layer,
The shape of the second layer substrate becomes complicated, and there is a concern that the magnetic properties may deteriorate.

Also, it is possible to provide a protective film layer between the first layer and the second layer of thin film magnetic heads, but after manufacturing the first layer magnetic head, the protective film layer is provided, and then the protective film layer is polished, etc. It is necessary to finish it into the required shape, and there is no hope of improving dimensional accuracy.
Further, there is a problem in that forming a thick protective film layer requires a large number of steps and costs.

Additionally, in order to manufacture a thin film magnetic head with a laminated structure, there is a method in which thin film magnetic heads are manufactured individually and then laminated together. Since this is a unit work, there is a problem in that it requires a large amount of man-hours and costs.

OBJECTS OF THE INVENTION In view of the current situation, an object of the present invention is to provide a substrate for a thin film magnetic head, which allows a thin film magnetic head having a laminated structure to be easily manufactured.

Structure and Effects of the Invention The present invention provides a structure in which the difference between the coefficient of thermal expansion of the soft ferrite plate and the coefficient of thermal expansion of the soft ferrite plate is 1xlO-6/d.
It consists of non-magnetic oxide-based ceramic plates with a coefficient of thermal expansion of EG or less, which are laminated with a glass adhesive layer interposed therebetween, and each soft ferrite has a surface roughness of 2008 or less on its outer main surface. This is a composite substrate for thin film magnetic heads.

By the method of this invention, a composite substrate consisting of three main layers of soft ferrite, ceramics, and soft ferrite is obtained, and since this composite substrate has a ceramic layer and a glass layer mainly for lamination bonding between the soft ferrite layers, two The soft ferrite layers are electrically separated, and magnetic circuits can be formed on each of the soft ferrite layer surfaces on the bidirectional surfaces of the substrate.

That is, as shown in FIG. 1, an erasing head (30) is formed on one soft ferrite layer (1) surface of a composite substrate (10) according to the present invention, and a recording head (30) is formed on the other soft ferrite layer (2) surface. A thin-film magnetic head with a bulk type structure for a floppy disk having a reproducing head (31) formed thereon can be manufactured.

Further, as shown in FIG. 2, a composite substrate (1
A recording head (32) is formed on one soft ferrite layer (1) surface of 0), and the recording head (32) is formed on the other soft ferrite layer (2)
A magnetoresistive element magnetic head having a configuration in which a reproducing head (33) is formed on the surface can be manufactured.

Disclosure of the Invention Based on the Drawings FIG. 3 is an explanatory assembly diagram showing a method of manufacturing a composite substrate according to the present invention.

The manufacturing method shown in FIG. 3 is a glazing method on one side of the non-magnetic oxide ceramic plate (3).

A glass layer (4) having a softening point of 400°C to 850'C and a coefficient of thermal expansion with a difference from the coefficient of thermal expansion of the soft ferrite plates (1) and (2) of 1X10-6/deg or less by sputtering. was applied and faced the main surface side of one soft ferrite plate (1) which was mirror-finished to a surface roughness of 500A or less, and the other soft ferrite plate (2) was mirror-finished to a surface roughness of 500A or less. A glass layer (4) having similar properties is applied to the main surface by a glazing method or a sputtering method, and this is mirror-finished to a surface roughness of 5008 or less than that of the ceramic plate (3). The glass layer (4) is laminated and adhered to the center side so that the glass viscosity of the glass layer (4) is 103 to iQ7.6.
Heat to a temperature of 0.1kcJ4 to 100k
Laminate molding is performed by applying pressing forces of g and J, and then the outer main surfaces of each soft ferrite plate (1) and (2) are polished to a surface roughness of 20 OA or less by diamond polishing or mechanochemical polishing. This is a manufacturing method for producing a composite substrate (10) according to the present invention, which is composed of multiple layers of soft ferrite (1), glass (4), ceramics (3), glass (4), and soft ferrite (2).

In the manufacturing method shown in Fig. 3, the glass layer (4) is applied to both surfaces of the ceramic plate (3) and laminated and crimped, or the glass layer (4) is applied to each ferrite plate (1M2). The mating material and main surface to which the glass layer is attached may be appropriately selected depending on the workability, the material of each layer, etc.

In addition, the glass layer (4) is first applied to the ceramic plate (3) and crimped to one of the ferrite plates (1), and the glass layer (4) is applied to the other ferrite plate (2). do,
These may be laminated and pressure-bonded together, and the mating material and main surface to which the glass layer is attached, and the lamination assembly order may be appropriately selected depending on workability, efficiency, the material of each layer, etc.

Also, between two soft ferrite plates with their mirror-finished main surfaces facing each other, the difference in thermal expansion coefficient from the soft ferrite plate is 1xlO.
A non-magnetic oxide ceramic plate having a thermal expansion coefficient of -6/deg or less and mirror-finished on both sides is interposed, and the softening point is 400' between the soft ferrite plate and the non-magnetic oxide ceramic plate. C~850'C,
The difference between the coefficient of thermal expansion of the above soft ferrite plate is 1XIO
-6/de(I) or less through a glass plate having a thermal expansion coefficient of less than
Heat to a temperature of 3 to 1076 poise, and reduce to 94 to 0.1
A manufacturing method may also be used in which lamination molding is performed by applying a pressure of ~1,004 Å, and then the outer main surface of each soft ferrite is polished to a surface roughness of 200 Å or less.

Preferred Embodiment of the Invention In this invention, the soft ferrite used is tlno 21 as the Mn Zn ferrite.
mo1%~38mo1%, Zn06m01%~2511
101%, Fe2O3 51mo1% to 56 mo1% is preferable, and as the NL Zn ferrite, NLO215mo1% to 25m01%, ZnO2
5mo1%~35m01%, Fe20349 mo1%
A composition of ~59 mo1% is preferred.

In addition, soft ferrite has a density of 99.9 of the theoretical density.
% or more, and the bore size is 0.
．． It is desirable that it is 5 or less.

The intermediate layer oxide ceramic is M2 if it is a non-magnetic ceramic whose coefficient of thermal expansion is less than or equal to IX 10-6/deq from the coefficient of thermal expansion of the soft ferrite plate.
O3 system, TiO2BaO system, TiO2-K,, O system,
ZrO2 series, r'1gO series or crystallized glass, etc.
Can be selected as appropriate. Also, the porosity of ceramics is 0, 0
1% or less is desirable.

Furthermore, if the difference between the coefficient of thermal expansion of the ceramic and the coefficient of thermal expansion of the soft ferrite plate exceeds lX10'''6/deg, cracks will occur in the ferrite or ceramic of the composite substrate, and the magnetic properties of the ferrite will deteriorate. This is not desirable because it causes

Glass mainly used for lamination and bonding has a softening point of 400°C to 8.
At 50℃, the difference between the thermal expansion coefficient of the soft ferrite plate is
Various types of glasses can be used as long as they have a coefficient of thermal expansion of 1×10'''6/deg or less, such as silicic acid glass, limestone glass, and high lead glass. It is desirable to have properties such as wear resistance and chemical stability.

Furthermore, if the softening point of the glass is less than 400°C, the required head dimensional accuracy cannot be obtained during the heat treatment of the magnetic film in the post-process, so it cannot be commercialized. When forming a ferrite layer, heating deteriorates the magnetic properties of the soft ferrite, which is not preferable, and the softening point is set at 400'C to 850'C.

Furthermore, if the difference between the coefficient of thermal expansion of the glass and the coefficient of thermal expansion of the soft ferrite plate exceeds 1 x 10-6 /deq, cracks will occur in the ferrite or glass of the composite substrate, and the magnetic properties of the ferrite will deteriorate. This is not desirable because it causes

In this invention, when bonding glass and ferrite, heating to a temperature that makes the glass viscosity 103 to 1075 poise is more than IQ7Fi poise, that is, at a temperature below the softening point of glass, the adhesive strength with soft ferrite is At a weak glass viscosity of 103 poise and a non-vortex temperature,
This is not preferred because the fluidity of the glass becomes too large, the intermediate glass layer flows and shape accuracy cannot be ensured, and the reaction between the ferrite and the glass is large, resulting in deterioration of ferrite properties and the formation of bubbles in the glass. This is because there is no

Also, when crimping glass and ferrite, o, 1h4~1
The reason for applying a pressure of 94 to 00 is that if it is less than 0.1 kiJ, the adhesion force will be weak and areas that are not bonded will easily be formed at the interface between the ferrite and the glass, and if it exceeds 9J to 100, the deformation will be large. This is because cracks are likely to occur in ferrite and glass.

In addition, in this invention, the reason why the surface roughness of the soft ferrite layer is limited to 200 Å or less is because a magnetic thin film is formed on this surface, and the surface roughness affects the characteristics of the thin film. A roughness is required, preferably 50 Å or less, and diamond polishing may be used, but mechanochemical polishing is desirable to obtain higher properties.

As for the diamond polishing method, abrasive grains: diamond, particle size 11 jrrI or less, lapping pressure: 0.01 uniform 42 to 1 uniform 4, rotation speed: 10 n
/m! n~100m/min.

Lap surface plate: SIl, CLL, cross conditions are preferable, and for the mechanochemical polishing method, abrasive grains: MgO, ZrO2, M2O3, 5i02 powder 1
The following conditions are preferable: particle size: 11 seconds or less, lap pressure: 0.01 k, 44-1 uniform deposition, rotational speed: 10 m/min to 100 m, 'min, wrap constant: Sn, solder, cloth.

The thickness of the composite substrate obtained by this invention is desirably 5 mm or less, preferably 0.1 mm to 2 mm, considering the purpose of use, alignment during pattern formation, ease of processing during mass production, etc. .

In addition, the thickness ratio between the ceramic layer and the soft ferrite layer of the composite substrate is appropriately selected depending on the application and usage method, but ceramic thickness/soft ferrite thickness =
0.01-1 is preferable.

In the manufacture of composite substrates, the glass layer thickness is 0.05 m.
If the thickness is 0.05 mm or more, a glass plate can be used, but since it is difficult to manufacture a glass plate with a thickness of less than 0.05 mm, the main surface of soft ferrite or ceramics is polished to a mirror surface using a glazing method or a sputtering method.

A glass layer can be deposited by a method such as the above, and the glass layer and ferrite or ceramics may be welded together, or the glass layers may be welded to each other, and soft ferrite and ceramics can be easily bonded by such a method. Note that when the glass layer is applied by the glazing method, bubbles may remain in the glass layer, but they can be eliminated by hot isostatic pressing in a subsequent step.

Examples Example 1 tlno 26.7 mo1%, ZnO20.8 mo1
%, Fe2O352,5mol1% crude, thermal expansion coefficient 10
6x10-7/deg, 50.8mm x 50.8mm lln ZTI series Huehuerite material thickness 0.4
It was cut into pieces with a surface roughness of 0.5 μm.

Also, 50.8+n+r+X50.8mmXthickness 0.2
Both sides of the 20 series plate were mirror-polished to a surface roughness of 500 Å or less at a T of mm dimension of 0°-.

Then, softening point 560'C1 thermal expansion coefficient 98X10-7
/deq lead is silicate glass mesh size 13
The paste No. 50 was screen printed on the mirror surface of the above ceramic plate using a #150 screen, held at 400°C in the air for 1 hour, and roughly heated at 850°C for 15 hours.
Hold and glaze for 20 minutes. A glass layer with a thickness of 5.3 m was formed, and then 5 β m of the glass surface was removed by mirror polishing to give a surface roughness of 5008 or less.

The mirror polished surface of ceramic glass was stacked on the mirror surface of two ferrite sheets and heated at 800'C in an N2 atmosphere.
(Temperature corresponding to the above-mentioned glass viscosity of 104 poise) and pressure bonded with a pressing force of 0.5 kmif.

The soft ferrite surface of the obtained multilayer composite substrate material is
It was finished to a surface roughness of 50 by mechanochemical polishing under the following conditions. The thickness of the obtained composite substrate was 0.7 mm, and the thickness of each soft ferrite was 0.25 m1Tl.

Mechanochemical polishing method using suspension in pure water Abrasive grains: MgO powder powder size Average particle size is 0, lap pressure crab
5th place in 0.1, rotation speed: 50m/min, lap surface plate; Sn.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of a thin film magnetic head using a composite substrate according to the present invention. FIG. 3 is an explanatory assembly diagram showing a method of manufacturing a composite substrate according to the present invention. FIGS. 4 and 5 are explanatory diagrams of a thin rattan magnetic head using a conventional substrate. 1.2...Soft ferrite plate, 3...Ceramics, 4...Glass layer, 10...Composite substrate, 30...
・Erasing head, 31... Recording/reproducing head, 32...
Recording head, 33... Playback head. Figure 1 Figure 2 Figure 4 [ Voluntary Procedures Book 1゜ Display of the Case 1985 Patent Application No. 77129 2 Title of Invention Composite Substrate for Thin Film Magnetic Head 3 Relationship with the Amendment Person Case Applicant Address: 5-22-4 Kitahama, Higashi-ku, Osaka, Agent 5, "Detailed Description of the Invention" column 1 of the specification subject to amendment, page 2 of the specification tube, line 7, "There is a magnetoresistive element head. " is corrected to "There is a magnetoresistive head, etc.". 2o "Internalized" on page 2, line 19 of the specification is amended to "internalized". 3. "Electrically" on page 4, line 19 of the specification is corrected to "magnetically." 4゜Correct [2oJ on page 9 of the specification cylinder, line 3] to rcaOJ. 5. Correct F glass and ferrite J on page 10, line 11 of the specification to "glass, ceramics, and ferrite." 6. On page 10, line 19 of the specification, "bubbles in the glass" is corrected to "bubbles in the glass." 7. "Glass and ferrite" on page 11, line 3 of the specification is corrected to "glass, ceramics, and ferrite." 8゜ "Ferrite and glass" on page 11, line 3 of the specification is corrected to "ferrite and ceramics and glass." 9. "Ferrite and glass" in lines 5 to 6 on page 11 of the specification is corrected to "F ferrite, ceramics and glass." 10. Correct rK20J on page 13, line 15 of the specification cylinder to rcao J.

Claims (1)

[Claims] 1. Between the two soft ferrite plates, the difference in coefficient of thermal expansion of the soft ferrite plates is 1×10.
It is constructed by laminating non-magnetic oxide ceramic plates with a thermal expansion coefficient of 6/deg or less through a glass adhesive layer, and the outer main surface of each soft ferrite has a surface roughness of 200 Å or less. A composite substrate for a thin film magnetic head, characterized in that it has the following characteristics: