JPH0235619A - Floating type composite magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the peeling of a metallic magnetic thin film or crack on a core piece from being generated and to obtain a satisfactory characteristic by setting th softening point and the yield point of glass for generating a magnetic core and the softening point of the glass to fix the magnetic core on a nonmagnetic slider at specific ranges. CONSTITUTION:The magnetic core 15 in which a pair of core pieces 21 and 22 are joined at a primary glass part 25 and the metallic magnetic thin film 23 is formed on the confronting plane of the core pieces 21 and 22, the nonmagnetic slider 11 having a slit 14 to house the magnetic core 15, and a secondary glass part 16 to fix the magnetic core 15 in the slit 14 are provided. And the primary glass part 25 is provided with the softening point less than a primary bonding temperature by >=70 deg. and the yield point higher than a secondary bonding temperature, and the secondary glass part 16 is provided with the softening point less than the secondary bonding temperature by >=70 deg.. In other words, specific relation between the thin film 23 and a heat treatment temperature is set. In such a way, it is possible to form a magnetic head in which no peeling of the thin film or not crack on the core piece is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a floating type composite magnetic head that is used in a magnetic disk drive by being floated very slightly above the surface of a recording medium, and a method for manufacturing the same.

[Prior Art and Problems to be Solved by the Invention] Magnetic heads used for writing and reading information in magnetic disk devices include, for example, those shown in U.S. Pat. No. 3,823,416 and Japanese Patent Publication No. 57-569. Floating heads are often used.

In this floating head, a magnetic conversion gap is provided at the rear end of the slider, and the entire head is made of an oxide magnetic material with high magnetic permeability.

A floating magnetic head makes light contact with the magnetic disk due to the force of a spring when it is stationary, but when the magnetic disk is rotating, the air on the surface of the magnetic disk moves and generates a force that lifts the bottom surface of the slider. acts on the magnetic disk, causing it to levitate from the magnetic disk. On the other hand, when starting and stopping the rotation of the magnetic disk, the magnetic head slides on the magnetic disk. To explain the contact situation when stopping the rotation of a magnetic disk, as the rotation speed decreases, the air flow on the surface gradually slows down. When the buoyancy of the magnetic head is lost, the magnetic head collides with the disk surface, rises due to the reaction, and falls back onto the disk surface. After repeating this movement several times, the magnetic head is dragged over the disk and then stops. The magnetic head must withstand such shocks when starting and stopping, and its performance is determined by C8S characteristics (c'contact 5t
art 5 top).

The floating magnetic head made of ferrite, which is a high permeability oxide magnetic material, exhibits relatively good C8S resistance, but its saturation magnetic flux density is low and it is unable to record sufficiently on high coercive force recording media. There is a drawback. In other words, even in Mn-Zn ferrite with a relatively high saturation magnetic flux density BS, B
s is about 5.0OOG at most.

Therefore, it has been found that it is desirable to have a magnetic head having a structure in which a metal magnetic thin film is disposed in the air gap so that 86 is 8.0 OOG or more. As an example of this,
As disclosed in Japanese Patent Application No. 14311, a magnetic head has been proposed in which a metal magnetic section with a high saturation magnetic flux density is provided only in the magnetic conversion gap of a floating magnetic head made of ferrite. However, in this example, the inductance after the magnetic transducer is wound with a predetermined wire is large, which lowers the resonant frequency, making recording and reproducing at high frequencies disadvantageous. The reason why the inductance is large is that the entire magnetic head is made of a magnetic material.

Therefore, it is necessary to make the magnetic circuit small in order to achieve low inductance. From this point of view, U.S. Pat.
No. 62.444.

In addition, the present inventors proposed a desirable shape of a magnetic head in which a magnetic core is embedded in a non-magnetic slider in Jikai No. 199219/1983.

From the above points, in order to obtain a floating composite magnetic head that can sufficiently record on high coercive force media and has a small inductance, it is necessary to use M-roll loberite with a high saturation magnetic flux density BS as a substrate and a high BS magnetic head in the gap part. It was found that a structure in which a magnetic core made of a thin film of magnetic material was embedded in a non-magnetic slider was superior.

The structure of the gap portion of the magnetic core to be incorporated into such a composite magnetic head is an oblique X-shaped structure as proposed in Japanese Patent Laid-Open No. 199217/1983, and a structure in which a gap portion is formed on the track surface of the magnetic core. There is a so-called parallel type that has a notch that regulates the width.

Both X-type and parallel-type magnetic cores generally consist of an R-type core piece and a C-type core piece, and usually Fe-A is placed on the I-type core piece.
A metal magnetic thin film such as t-8i is formed. Note that the parallel type magnetic core has the advantage that it is easy to form a magnetic gap and the track width can be defined accurately.

However, since the difference in thermal expansion coefficient between the metal magnetic thin film and the core piece is generally relatively large, when the core piece is joined with glass or the magnetic core is fixed to a non-magnetic slider, the metal magnetic thin film is separated from the core piece. There are problems in that the core pieces may peel off or cracks may occur in the core pieces due to internal stress at the thin film joints. If the magnetic thin film peels off or cracks occur in the core piece, small peaks (sub-peaks) will appear in areas other than the original signal due to the pseudo-gap effect, and the reproduction characteristics will deteriorate.

Various attempts have been made to solve the above problems. For example, in order to prevent problems such as peeling and cracking due to differences in thermal expansion coefficients, it is conceivable to make the metal magnetic thin film thinner, but this is not preferable because head characteristics deteriorate as the metal magnetic thin film becomes thinner.

In addition, in the assembly process of such a composite magnetic head, first, a C-shaped core piece and a ■-shaped core piece are joined to create a magnetic core, which is placed in the slit of the slider, and then a glass rod is placed. By heating this to a high temperature,
Glass is poured into the gap between the slider and the magnetic core. As a result, the magnetic core is fixed to the slider. However, if the temperature at this time is too high, the gap portion of the magnetic core, which is also made of glass, will loosen and widen, causing a problem that the characteristics of the magnetic head will deteriorate. Therefore, it is necessary to use low melting point glass in the magnetic core assembly process. Conventionally, the following glasses have been used as typical low-melting glasses.

Corning glass 8463 softening point and thermal expansion coefficient softening 9
Point (t) 377 Coefficient of thermal expansion (x
lO-'/deg) 105 (25 to 310°C) However, since this low melting point glass has low strength, cracks are likely to occur due to slight differences in thermal expansion coefficients.

It also has problems such as poor weather resistance and easy discoloration.

Therefore, the present inventors first developed Mn-Z, which is a ferromagnetic oxide.
In a bonding glass for assembly of a core part made of n-ferrite and a part of a slider made of nonmagnetic ceramics, its composition is 5iOz: 9 to 12 wt%, LL: 3 to 9 wt%
, At203: 3-6 wt%, PbO: 76
An application has been filed for a bonding glass for composite magnetic head assembly characterized by a concentration of ~82 wt% (Japanese Patent Application Laid-Open No. 60-243182).

This bonding glass has a softening point of 404-446°C and a softening point of 87.6-96.4
It has a coefficient of thermal expansion of between 280°C).

However, although the above-mentioned low melting point glasses have sufficiently low melting points for assembling magnetic cores, they are not necessarily satisfactory in terms of corrosion resistance, especially acid resistance and water resistance.

Therefore, discoloration may occur during the cleaning process after assembly, etc.
Alternatively, there have been problems such as a significant level difference occurring between the magnetic core or slider and the glass surface.

On the other hand, with regard to the bonding glass of the magnetic core, if its softening point is too high, the primary bonding temperature will become too high, causing problems with peeling of the metal magnetic thin film, and if its yielding point is too low, it will cause problems during secondary bonding. There is a risk that the magnetic gap will fluctuate.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a floating composite magnetic head having a magnetic core on which a metal magnetic thin film is formed, which does not have the above-mentioned problems, and a method for manufacturing the same.

Another object of the present invention is to provide a flying composite magnetic head having a magnetic core bonded with glass having a low softening point and a sufficiently high yielding point, and a method for manufacturing the same.

Still another object of the present invention is to provide a floating composite magnetic head in which a magnetic core is bonded to a non-magnetic slider using a low-melting bonding glass having good corrosion resistance, and a method for manufacturing the same.

[Means to solve the problem]

As a result of intensive research for the above purpose, the present inventor determined that the softening point and yield point of the primary glass for making the magnetic core, and the softening point of the secondary glass for fixing the magnetic core to the non-magnetic slider, were determined at the primary bonding temperature. It has also been discovered that by setting the secondary bonding temperature within a specific range, there is no problem of peeling off of the metal magnetic thin film or cracking of the core piece, thereby making it possible to obtain a magnetic head exhibiting good characteristics. We have also discovered that by correlating the primary bonding temperature with the thickness of the metal magnetic thin film, it is possible to obtain a magnetic head free of the above problems. Furthermore, the present inventor reduced the content of SiO2 and
It has been discovered that by increasing the content of , a bonding glass with a lower melting point and improved corrosion resistance can be obtained. Based on this discovery, the present invention was completed.

That is, the floating type composite magnetic head of the present invention includes (a) a magnetic core in which a pair of core pieces are joined by a primary glass portion, and a magnetic thin film of gold is formed on at least one opposing surface of the core piece; (b) a non-magnetic slider having a slit for accommodating the magnetic core; and (c) a secondary glass portion for fixing the magnetic core within the slit, wherein the primary glass portion is 70° C. higher than the primary bonding temperature. The secondary glass portion has a softening point lower than or equal to or higher than the secondary bonding temperature and a yield point higher than the secondary bonding temperature, and the secondary glass portion has a softening point lower than the secondary bonding temperature by 70°C
It is characterized by having a lower softening point.

In the floating composite magnetic head of the present invention, the preferable composition of the primary glass portion is 5i0235 to 40% by weight, B2C
It is characterized by consisting of 1.9 to 15% by weight, 9 to 12% by weight of alkali metal oxide, and 36 to 42% by weight of Pb. As the alkali metal oxide, Na, 0 is particularly preferable. In addition, the preferable composition of the secondary glass part is particularly 4.5 to 8
．． 5% by weight of 8102 and 4.5-9.5% by weight of B1
0. and 6-8% by weight of ALaDz, and 77.5-82
, 5% by weight of PbO.

Further, in the method for manufacturing a floating composite magnetic head of the present invention, the primary bonding temperature T, (t
) is the following formula;

), and the secondary bonding temperature T2 for forming the secondary glass portion is 530° C. or less.

[For production]

A metal magnetic thin film needs to be thicker than a certain level to produce good playback output characteristics, but as it gets thicker it needs to be heat treated! M-separation and cracks in the core pieces are likely to occur. Therefore, by setting the thickness of the thin film and the heat treatment temperature in a specific relationship, it is possible to form a magnetic head that does not cause peeling of the thin film or cracking of the core pieces.

〔Example〕

The invention will be explained in detail below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the overall structure of a floating composite magnetic head according to an embodiment of the present invention. 11 is a non-magnetic slider, I2 and I3 are sight rails provided on the slider 11, 14 is a slit portion provided in the sight rail 13, 15 is a magnetic core embedded in the slit portion 14, and 16 is the magnetic core 15. This is the glass part that is fixed. The slider 11 has a thermal expansion coefficient of 105 to 115X1.
It is preferable to use a non-magnetic ceramic made of CaTi0* with a porosity of 0-'/t and a porosity of 0.5% or less.

FIG. 2 is an enlarged perspective view of the magnetic core 15. 21.22
are magnetic materials called a C-type core piece and an I-type core piece made of In-Zn ferrite, respectively, and 23, 23'
is the Fe-AL-S+ thin film deposited on the I-shaped mouth 7 piece. Reference numeral 24 denotes a winding window formed between the C-shaped core piece 21 and the R-shaped core piece 22, and a primary glass part 25 for joining the C-shaped core 21 and the ■-shaped core piece 22 is provided above the window. It is being

A notch 26 is formed in the track surface of the magnetic core 15 to regulate the track width Tw. The notch 2G extends in the longitudinal direction of the magnetic core 15. Thereby, the track width Tw of the magnetic gap 27 can be set arbitrarily. Note that the magnetic gap 27 is formed by a gap regulating film such as 5IO7 deposited by sputtering or the like. The shape of this magnetic core is generally as follows.

Track width Tw 13-20μm Magnetic gap length GA 0.5-0.8μm Magnetic gap depth Gd 2-15μm Core width
150-170 μm This magnetic core can be manufactured by the following process. First, blocks of ferrite material to form the I-shaped core pieces and the C-shaped core pieces are created.

As the ferrite material, Mn--Xn ferrite having a high Bs and as large a magnetic permeability as possible at high frequencies is desirable. In addition, in order to reduce the voids that occur in the glass during glass bonding, hot isostatic press (hat l5ost)
It is preferable to use one that has been densified by the atomic press method. Especially B, o=4700-5400
G, Hc = 0.1 = 0.20e, magnetic permeability at 5 MHz 81) 0-1300, porosity 0.5% or less, thermal expansion coefficient 105-130 x 10-'/l: Mn- Zn
Although it is preferable to use polycrystalline ferrite, a single crystal material may be used instead of polycrystalline ferrite.

A metal magnetic thin film is formed on one of the core blocks,
It is easier and preferable to provide it in the I-type core block. The metal magnetic thin film is preferably a Fe-AL-Si alloy deposited by sputtering.

The sputtering conditions are 5~5 to maintain stable discharge.
An Ar gas pressure of 12 mTarr is desirable. In addition, electric power prevents cracking due to temperature rise in the alloy target, and
In order to obtain a film production rate of about 0.00 people/min,
200W (example of target with diameter 150 mtn)
is desirable.

In order to obtain high magnetic permeability, the composition of the Fe-At-31 film is 83 to 86% Fe, 5 to 8% AL, and
8-11% Si is preferred. In particular, for the purpose of reducing the magnetostriction constant, 83.5 to 85% Fe, 5 to 7
% At and 9 to 1015% Si are desirable. F
A trace amount of additives may be added to the e-At-5i film for the purpose of improving corrosion resistance. In this case, less than 2% by weight of TI
, Ru, Cr, etc. are preferably added singly or in combination.

When partially forming the Fe-At-51 thin film, a mask sputtering method is used. The mask sputtering method is generally performed using a combination of a type 1 core piece holder and a mask with an opening in the area where the thin film is to be formed. A thin film is formed on the ferrite core at desired areas through the opening of the mask by sputtering.

The thickness of the Fe-AL-5i thin film is determined in consideration of magnetic head characteristics and problems of peeling and cracking. FIG. 3 is a graph schematically showing the general relationship between film thickness, magnetic permeability, and reproduction output. In the figure, a is the playback output at 5MHz, b, c
indicate the magnetic permeability at 1 Mt (z) and 514 Hz, respectively. As is clear from FIG. 3, as the film thickness increases, both the reproduction output and the magnetic permeability tend to increase.

In practice, when the Fe-AL-5i thin film has a thickness of 1.5 μm or more, satisfactory reproduction output and magnetic permeability can be obtained. However, if the film thickness becomes too large, problems such as separation from the core piece and cracking of the core piece will occur due to heating during the bonding process. Generally, when the film thickness exceeds 5 μm, peeling and cracking are likely to occur at normal primary bonding temperatures. Therefore, the thickness of the Fe-At-51 thin film is 1.5 to 5 μm.

Next, as shown in FIG. 4, the Fe-Al-5i film 53.5
The C-shaped core block 51 is brought into contact with the ■-shaped core block 52 on which 3' is partially attached, set in the jig 56, and the screws 5
Tighten and fix with 7. In this state, the primary glass rod 55 placed in the winding window 54 is heated and injected to join both core blocks (primary bonding).

A magnetic core can be obtained by cutting this joint block and providing a notch for regulating the track width 7w.

This magnetic core is fixed to the slit portion of the slider (secondary bonding) as follows.

FIG. 5 shows that the bonded magnetic core 63 is installed in the slit part 62 of the slider 61, and the secondary glass rod 68 is
6 is a partial perspective view showing a state in which the slider 61 is placed on the upper surface of the slider 61. FIG. Since the notch 65 of the magnetic core 63 is directed toward one end 64 of the slider, even if the magnetic core 63 is pressed against the one end 64, a gap 67.69 is secured between it and the inner surface of the slit part. . Fixation of the magnetic core 63 is easily achieved by temporary fixation using a spring member 66. The secondary glass rod 68 fixes the magnetic core 63 to the slit portion 62 as a secondary glass. After fixing with secondary glass, the air bearing surface of the magnetic head is ground and polished to complete the magnetic head.

In the manufacturing process of the magnetic head as described above, there is the following heating process.

(1) Primary bonding process: Bonding core pieces with primary glass.

(2) Secondary bonding process: The magnetic core is fixed to the slit of the non-magnetic slider using secondary glass.

In the secondary bonding process, the primary glass of the magnetic core is also heated, so there is a risk that the magnetic gap may be deformed. In order to completely prevent this, it is necessary that the yield point of the primary glass is higher than the secondary bonding temperature. In addition, in order to sufficiently fluidize the primary glass and secondary glass in the primary bonding process and secondary bonding process, the primary bonding temperature and secondary bonding temperature must be sufficiently higher than the softening points of the primary glass and secondary glass, respectively. There is a need. Specifically, these requirements are as follows.

(1) Primary glass: has a softening point that is 70°C or more lower than the primary bonding temperature and a yield point that is higher than the secondary bonding temperature.

(2) Secondary glass...70 from the secondary bonding temperature
It has a softening point lower than ℃.

However, as for secondary glass, the corrosion resistance also decreases as the softening point decreases. Therefore, the softening point of the secondary glass must be above a certain level. From this point of view, specifically, the softening point of primary glass is 540 to 630°C, especially 56°C.
0 to 580°C, the yield point is preferably 500 to 530°C, and the softening point of the secondary glass is 410 to 450°C.
It is preferable that In this case, the primary bonding is 6
40-730℃, secondary bonding 490-530℃
It is preferable to carry out the process at a temperature range of .

Although there are many possible combinations of bonding glass (primary glass) having PbO-3+02 as the main component and various other elements as a bonding glass (primary glass) having the above-mentioned characteristics, the results of experiments conducted by the present inventors indicate that the following system is suitable.

(a) P bO-3i O2 with alkali metal oxide (
20, L120, Na2O, etc.).

(b) A system in which an alkali metal oxide is added to PbO-5iOz-B2Oi.

(c) A system in which an alkali metal oxide is added to PbO-3i02-BJ*-AL203.

Preferred composition ranges for such systems are as follows on a weight basis.

(a) 243-49% Sin, 44-59% Pb
O17-13% alkali metal oxide.

28-49% 3102.5-15% B2O5.
7-13% alkali metal oxides, balance PbO0 (c) 28-49% 8102.5-15% B2O3
．． The coefficient of thermal expansion of the above primary glass is generally 94-103X
It is lO-'/l.

Among these, the composition of the primary glass is particularly preferable, on a weight basis, 35 to 40% SiO□, 9 to 15% B20°, 9
~12% alkali metal oxides, 36-42% PbO
It consists of Na2 as alkali metal oxide
O is particularly preferred. The primary glass of this composition is 505-5
It has a yield point of 20°C. Using this primary glass,
As shown in FIG. 6, when a sendust thin film of about 2 μm is formed on a ferrite core, the core pieces can be bonded at a primary bonding temperature of 680° C. or lower.

In the above composition, the range of SiO2 is 35 to 40% by weight.
This is because when 5hot increases above 40% by weight, the softening point of the secondary glass increases, and at a bonding temperature below 680°C, the primary glass will not flow in. Conversely, when 5hot increases below 1% by weight, This is because the yield point of the primary glass is lowered, and there is a risk that the magnetic gap may become loose during bonding between the slider and the magnetic core. Also B20. The range of 9 to 15% by weight is B, 0.
If it increases more than 15% by weight, the thermal expansion coefficient of the glass decreases, while if it is less than 9% by weight, the thermal expansion coefficient of the glass increases, causing problems such as cracks in the glass due to bonding with the ferrite core. This is because problems arise.

Furthermore, the range of alkali metal oxide (Na20) is 9 to 1.
The reason why the content is 2% by weight is that if the content is more than 12% by weight, the yield point of the glass will decrease and the thermal expansion coefficient will increase, whereas if it is less than 9% by weight, the softening point of the glass will increase and the thermal expansion coefficient will increase. This is not preferable because it causes a decrease in the coefficient. Further P
When bO exceeds 42% by weight, the deformation point of the glass decreases, whereas when it is less than 36% by weight, it increases the softening point of the glass and decreases the specific gravity of the glass, so that the glass no longer flows. Undesirable.

The yield point is important because the yield point of the primary glass is correlated with the loosening of the magnetic gap during secondary bonding between the magnetic core and the slider. If the secondary bonding temperature between the magnetic core and the slider is, for example, 505°C, glass with a yield point of less than 505°C is undesirable because it will cause the magnetic gap to loosen (and conversely, glass with a yield point of 520°C is undesirable). If the glass exceeds the temperature range, the softening point will also be high, resulting in poor inflow of the glass, which is not preferable.

A particularly preferred example of this primary glass is 40PbO-37S iO□-13B20-1ONa on a weight basis.
-0 composition has a softening point of 560℃ and a thermal expansion coefficient of 95X.
10-'/t). The bonding strength of the magnetic core bonded using this glass is 5 kg/m
+a', which is satisfactory, and no erosion of the Fe-At-5i film is observed.

Note that SiO□ has the effect of preventing corrosion of glass under high humidity. However, on the other hand, if there are too many S+02, Fe-A
The wettability with the t-5i film or Mn-Zn ferrite deteriorates, and the bonding strength cannot be maintained. ALzOs prevents the glass from discoloring at high temperatures, but on the other hand, if it is present too much, the softening point becomes high and bonding becomes impossible. The alkali metal oxide neck also has the effect of regulating the fluidity of the glass.

On the other hand, as a secondary glass having the above properties, the weight-based tear is 0 to 83% (7), PbO13 to 1O%, At20
1.4~10%Si(]2.4~10%(7) B,
B30) There are compositional characteristics. This thermal expansion coefficient is 87-9
6X 10-'/t.

As a preferable example, 80Pb loaf A120s-6
3iL-7B, 03 (wt%). The coefficient of thermal expansion of this glass is 93X to-'/t: and the softening point is 440°C. For example, 530℃ using this glass.
If it is firmly fixed, it is possible to join without fear of cracking.

Further, a preferred composition of the secondary glass having a low softening point and excellent corrosion resistance is as follows.

5I02 4.5-8.5% by weight B20.
4.5-9.5 wt% AtxOs 6-
8 wt% Pb0 77, 5-82.5 wt% S+Oz
is 4.5 to 8.5% by weight, because if it is less than 4.5% by weight, the glass will crystallize or the weather resistance and acid resistance will be lowered, and if it exceeds 8.5% by weight, At20, This is because the softening point increases due to the synergistic effect with glass, and the inflow property of the glass decreases. A more preferable content of S+02 is 5 to 7% by weight.

The reason why A1.03 is 6 to 8% by weight is that if it is less than 6% by weight, the weather resistance and acid resistance will be low, and if it exceeds 8% by weight, the softening point will also rise and the flowability of the glass will decrease. It comes out. A more preferable AtzCb content is 6.5 to 7.
It is 5% by weight.

Since B2O3 has the function of regulating the coefficient of thermal expansion within an appropriate range, it is preferably in the range of 4.5 to 9.5% by weight. Specifically, if it is less than 4.5% by weight, the coefficient of thermal expansion becomes large, and if it exceeds 9.5% by weight, the coefficient of thermal expansion becomes small. Furthermore, B2O. If the content of is small, crystallization of glass is more likely to occur.

More preferably, it is in the range of 6 to 7% by weight.

In the system with the above composition, the range of PbO is 77.5 to 82.
The reason why the content is limited to 9% by weight is that if the content is increased more than this, the glass will crystallize, whereas if it is less than this, the glass softening point will rise and the flow will be poor. More preferred Pb
The content of O is 78-82% by weight.

The secondary glass having the above composition has a softening point of 412 to 436°C and a coefficient of thermal expansion of 88 to 96X 10-7/t at 30 to 280°C. Although this softening point and coefficient of thermal expansion are substantially the same as those of the bonding glass disclosed in JP-A-60-243182, the secondary glass of the present invention also has significantly better environmental resistance, i.e., water resistance. , moisture resistance and acid resistance. In particular, the acid and water resistance of the glass is extremely important in order to prevent discoloration of the glass during the cleaning process after the completion of the magnetic head, or to prevent a level difference between the magnetic core or slider and the glass surface caused by the elution of glass into the cleaning solution. This is a major factor, and the feature is that this point has been improved. Therefore,
By using the secondary glass of the present invention, a highly reliable magnetic head with excellent weather resistance can be obtained.

Next, in order to prevent peeling of the thin film and cracking of the core, it is necessary to correlate the primary bonding temperature with the magnetic thin film made of Fe-At-31 alloy.

In general, (1) as the magnetic thin film becomes thicker, peeling and cracking become more likely to occur; (2) for the same film thickness, as the primary bonding temperature increases, peeling and cracking become more likely to occur.

Therefore, we investigated the presence or absence of peeling and cracking on Fe-At-5i thin films of various film thicknesses by applying various heat treatment temperatures, and found that film thickness W (μm) and primary bonding temperature T1 (°C)
It has been found that peeling and cracking do not occur when the following relationship is satisfied between:

T, ≦aTI+ b = 25≦a≦-15 720≦b≦770 That is, the primary bonding temperature T has a linear function relationship with the film thickness W, and the primary bonding temperature decreases as the film thickness increases. Note that the primary bonding temperature needs to be 70° C. or more higher than the softening point Ts of the primary glass.

The present invention will be further explained in detail by the following specific examples.

Example 1 To form a magnetic core with the structure shown in Figure 2,! J
A C-type core block and an I-type core block made of n-ln polycrystalline ferrite were created. Mn-Zn polycrystalline ferrite is densified by hot isostatic pressing, so the porosity is 0.1%, and the magnetic properties are Bl
a = SiO0G, l1c = 0.150e, 5
The magnetic permeability at MHz was 950, and the coefficient of thermal expansion was 115XIO-'/l:.

Each C-type core block and I-type core block was formed using a peripheral slicer, ground using a surface grinder, and then polished using a lapping machine. After polishing, the sample was boiled in trichlorethylene, ultrasonically cleaned in trichlorethylene, acetone, and alcohol, followed by Freon boiling, and finally cleaned with Freon steam.

Next, Fe-Aj-5i thin films of various thicknesses and widths were formed at positions corresponding to the magnetic gap and back gap on the I-type core block using a magnetron sputtering device. The input power of magnetron sputtering equipment is 0.8
kW, argon pressure 8 mTorr.

The substrate temperature was 200°C. In addition, the Fe-AL-8i thin film contains 85% Fe, 6% AI, and 9% 8% by weight.
It had a composition consisting of 1.

I-type core blocks on which Fe-At-5i thin films of various thicknesses were formed were heat-treated at various temperatures from 500 to 750°C, and the presence or absence of peeling was examined using a microscope. The results are shown in Figure 6. In the drawings, ○ indicates no peeling, and × indicates peeling. As is clear from FIG. 6, no peeling was observed in the area, there was a mixture of peeling and non-peeling in the border area, and peelability was observed in all areas C. Region A is the above formula T, ≦ail-b,
The range satisfies a=approximately −20° and b=approximately 730.

Example 1 & An RP sputtering device was used on an I-type core block on which a 2 μm thick Fe-AL-Si thin film was formed in the same manner as in Example 1. A 0.5 μm thick 5iO gap regulating film was formed at the substrate temperature.

Further, the C-type core block and the I-type core block were bonded together using primary glass having the composition shown below.

PbO 40% by weight S+0□ 37% by weight, 0 10% by weight B, 0. 13% by weight This primary glass had a softening point of 573°C, a yield point of 520°C, and a coefficient of thermal expansion of 96×10-'/t. To join the core block with the primary glass, heat in an electric furnace in N gas at a heating rate of 200°C/hour, and then raise the temperature to 700°C for 3
This was done by holding for 0 minutes.

The core blocks thus joined were ground and polished using a surface grinder and a lapping machine, and after being cut to a thickness of 250 μm using a peripheral slicer, both sides of the core were polished using a lapping machine to produce a 152 μm core. .

Next, in order to define the track width Tw of each magnetic core, a high-rigidity dizer is used to determine the track width Tw of 138.5 μm in width and 200 μm in depth.
A notch of m was formed.

The structure of the magnetic core thus obtained was as follows.

Magnetic core width Cw 152μm track width
Tw 13.5μm gap length Gl
O, 55μm Gap depth Gd 5
μm Thickness of bonded glass Gw Approximately 200 μm However,
The gap depth Gd is the value after the magnetic head is assembled and the air bearing surface is polished.

Furthermore, CaTi0. with a thermal expansion coefficient of 108X 10-'/t: and a porosity of 0.15%. A slit portion with a length of 1.5 mm and a width of 220 μm is formed at the end of one site rail of a slider made of ceramic, and the above magnetic core is fixed in the slit portion with a leaf spring, and a secondary glass having the following composition is formed. It was firmly fixed.

Pb0 79.5% by weight 5i029.5% by weight AL20* 4.0% by weight B20° 7.0% by weight The coefficient of thermal expansion of the secondary glass is 94X 10-'/t:,
Softening point is 420℃, transition point is 369℃, yield point is 396℃
It was ℃. This was heated in an electric furnace under nitrogen at a heating rate of 200° C./hour and held at a temperature of 500° C. for 30 minutes, thereby flowing into the gap between the slit portion and the magnetic core. The air bearing surface of the magnetic head obtained in this way is ground and polished using a mirror grinder and a lapping machine, and it floats! !
2 composite magnetic heads.

Using this magnetic head, we recorded a flying height of 0.3 μm and a peripheral speed of 12.1 on a 5.25-inch magnetic disk with a Co-Ni sputter recording medium (Hc = 11500e).
Reproduction output characteristics at 5 MHz at m/s (10-,
The output waveform relative to the vertical waveform was measured. Note that the winding of the magnetic head had 48 turns. The results are shown in 7th rgJ.

In the figure, a and b indicate the envelope of a signal containing noise.

Main beak height E. Sub peak E2nd for ut
The height ratio; is a parameter that determines the quality of reproduction, and generally needs to be 5% or less, but in this example it was 3%, which was good. It is thought that the appearance of sub-peaks is correlated with the adhesion state of the thin film, and if there is peeling, sub-peaks appear due to the pseudo gap effect.

Example 3 Fe-Al-5i thin films of various thicknesses were formed in the same manner as in Example 2, and the peak of the reproduction output was was measured and ε (%) was determined. The results are shown in FIG. It can be seen from this that ε (%) increases as the film thickness increases and as the primary bonding temperature increases.

Based on the results shown in FIG. 8, the allowable range of bonding temperature with respect to film thickness was determined. The results are shown in Figure 9. In FIG. 9, region A shows the allowable range of primary bonding temperature, and region B shows the allowable range of secondary bonding temperature. This figure shows that the film thickness is 1.5 in the magnetic head of this example.
In the case of μm, the primary bonding temperature T1 is approximately 710°C
Hereinafter, when the film thickness is 5 μm, T is 645° C. or less. Also, since the softening point of primary glass is 573°C,
T1 needs to be 643°C or higher. On the other hand, the yield point of primary glass is 520℃, and the softening point of secondary glass is 420℃.
Therefore, the range B of the secondary bonding temperature is 490~
The temperature is 520°C.

Implementation example 4 A comparative test was conducted using 16 types of glasses shown in Table 1.

The slider and core used have thermal damage coefficients of 108X 10-'/t: and 117X 1, respectively.
0-'/t: CaTi[]* slider n-
The core is made of Zn ferrite. This slider and core are machined as shown in FIGS. 1 and 2. This slider 11 and magnetic core I5 were combined, a secondary glass rod 68 was placed as shown in FIG. 5, and this was heated at 540° C. for 10 minutes in a nitrogen atmosphere. Further, as shown in FIG. 10, lapping was performed up to the machining allowance 101 to obtain a magnetic head. Each of the obtained magnetic heads was immersed in a 0.020% by weight phosphoric acid aqueous solution (20° C.) for 10 seconds, and then thoroughly dried and smoked. Thereafter, the amount of erosion of each glass was measured.

The results are also shown in Table 1.

Table (Note) (1): Based on the results of the thermal expansion coefficient at 3G to 280°C, those with glass erosion steps of less than 2Or++n are judged to be acceptable. Sample No. 5.
It can be seen that ten types of glasses rated 6.7 and 9 to 15 have good acid resistance. This shows that the glass of the present invention has excellent acid resistance compared to the conventional low melting point glass (Nα 2.3) of JP-A-60-243182.

Next, a water resistance test and a humidity resistance test were conducted on the above 10 types of glasses. First, when the glass was immersed in pure water at 60° C. for 2 hours and the erosion level difference of the glass was measured, both were less than 20 nm, indicating good water resistance. Furthermore, no discoloration of the glass was observed in a 96-hour humidity test at 60° C. in a 90% 12H atmosphere, indicating that the glass was immersed in moisture resistance.

Example 5 A 5in2 film and a glass film were formed by sputtering on the L-shaped core piece and the C-shaped core piece to which the sendust film was attached, respectively, and assembled using the jig shown in FIG. 4. A primary glass rod (diameter 0.20 to 0.25 mm) having a composition shown in Table 2 below was placed in this winding window and heated in an N2 atmosphere to perform primary bonding. The temperature conditions at this time are as shown in FIG. The bonded core thus obtained was cut to observe the flow state of the primary glass. As shown in FIG. 12, the glass inflow condition was judged as "good" if the primary glass was filled up to the apex 30 of the core, and "bad" if it was not. The results are shown in Table 3.

Secondary glass S10゜8.03 LxOv PbO Softening point Ts Thermal expansion coefficient α (between 30℃ and 280℃) 6.0wt1% 7.5wt% 65wt% 80.0wt% 419℃ 92X 10- From the results shown in Table 3 and Table 4, when primary bonding is performed at 680°C or lower, 35 to 40% of 5in 2.9 to 15% of B2O
It can be seen that primary glasses that do not meet the compositional requirements of 3.9-12% NazO and 36-42% PbO do not have sufficient fluidity.

Next, as shown in FIG. 5, a magnetic core was set in the slit of the slider, and secondary bonding was performed using a secondary glass rod having the composition shown below. Since the optimum bonding temperature for this secondary glass is 505° C., secondary bonding was performed at that temperature, and at that time, fluctuations in the magnetic gap of the magnetic core were measured. The results are shown in Table 4.

From the above results, it can be seen that in sample Nα5 (the primary glass is outside the above composition range), the magnetic gap changes due to secondary bonding at 505°C.

In this way, 35-40% SiO2.9-
15% B2O3.9-12% Na2o and 36-4
Using a primary glass with a composition of 2% PbO, 68
If primary bonding is performed at 0° C. and secondary bonding is performed at 505° C., a good composite magnetic head can be obtained without peeling of the Sendust thin film or loosening or widening of the magnetic gap.

〔Effect of the invention〕

As detailed above, the floating composite magnetic head of the present invention is not only assembled with primary glass and secondary glass having temperature characteristics within a predetermined range, but also has a Since it is formed at the bonding temperature and secondary bonding temperature, there is no problem of magnetic film peeling or cracking of the core piece, and it has good reproduction output characteristics.

Further, by using the preferred primary glass and secondary glass of the present invention, it is possible to obtain a magnetic head without peeling of the metal magnetic thin film or fluctuation of the magnetic gap.

Furthermore, since the secondary glass has relatively good acid resistance, a composite magnetic head with less glass discoloration can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a floating type composite magnetic head according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an example of a magnetic core incorporated in the floating type composite magnetic head of FIG. 1. Figure 3 is a graph showing the general relationship between the film thickness of a metal magnetic thin film, magnetic permeability, and reproduction output, and Figure 4 is a graph showing the general relationship between the thickness of a metal magnetic thin film, magnetic permeability, and reproduction output. 5 is a sectional view showing a state inserted into a wire window; FIG. 5 is a partial perspective view showing a process of fixing a magnetic core to a slider in order to manufacture the floating type composite magnetic head of FIG. 1; FIG. Figure 6 is a graph showing the presence or absence of film peeling at various film thicknesses and heat treatment temperatures, Figure 7 is a graph showing regeneration peaks, and Figure 8 is a graph showing film thickness and ε (%) at various primary bonding temperatures. 9 is a graph showing the relationship between film thickness and bonding temperature. FIG. 10 is a cross-sectional view showing the process of lapping the magnetic head of the magnetic core assembly machine. FIG. 11 is a graph showing an example of temperature conditions for secondary bonding, and 12th ffl is a partial sectional view showing how the primary glass flows in the magnetic gap due to primary bonding. 11...Nonmagnetic slider 12.13...Sight rail 14...Slit portion 15...Magnetic core 16...Secondary glass portion 21...C-shaped core 22...I-shaped core 23 .23' -Pe-AL-5t thin film 24... Winding window 25... Primary glass portion 26... Magnetic core spark 27... Magnetic gap 30... Apex 51... ...C-type core block 52...I-type core block 53.53' -Fe-,4L-Si thin film 54...
Winding window 55...Primary glass rod 61...Slider 62...Slit 1 63...Magnetic core 64...One end of slider 65...Notch 6B of magnetic core...・Magnetic core fixing spring material 67.69...Gap 68...Secondary glass rod 1 (11...Machining allowance Tw...Track width applicant Hitachi Metals Ltd. Patent attorney Taka Ishi Tachibana Ma Figure 3 Film thickness (μm) Figure 6 Film thickness (, u7rL) Figure 7 Figure 8 Figure 9 Figure 1 Figure 12

Claims (8)

[Claims] (1) (a) A magnetic core in which a pair of core pieces are joined by a primary glass part and a metal magnetic thin film is formed on at least one opposing surface of the core pieces, and (b) a slit for accommodating the magnetic core. and (c) a secondary glass portion that fixes the magnetic core in the slit, wherein the primary glass portion has a softening point that is 70° C. or more lower than the primary bonding temperature. A floating composite magnetic head characterized in that the secondary glass portion has a yield point higher than a secondary bonding temperature and a softening point lower than the secondary bonding temperature by 70° C. or more. (2) In the floating composite magnetic head according to claim 1, the primary glass portion has a softening point of 560 to 580°C and a
It has a yield point of 00 to 530°C, and the secondary glass part has a
A floating composite magnetic head characterized by having a softening point of 10 to 450°C. (3) In the floating composite magnetic head according to claim 1 or 2, the primary glass portion contains 235 to 40% by weight of SiO, 39 to 15% by weight of B_2O, 9 to 12% by weight of alkali metal oxide, and 36 to 42% by weight of PbO. % by weight, and has a yield point of 505 to 520°C. (4) The floating composite magnetic head according to claim 3, wherein the alkali metal oxide is Na_2O. (5) In the floating composite magnetic head according to any one of claims 1 to 4, the secondary glass portion is made of SiO_2
4.5-8.5% by weight, B_2O_3 4.5-9.5
wt%, Al_2O_3 6-8 wt%, and PbO
A floating composite magnetic head comprising 77.5 to 82.5% by weight. (6) In the floating composite magnetic head according to claim 5, the softening point of the secondary glass portion is 412 to 436°C;
Thermal expansion coefficient at 0 to 280℃ is 88 to 96 x 10^
A floating composite magnetic head characterized by a temperature of −＾7/°C. (7) (a) a magnetic core in which a pair of core pieces are joined by a primary glass part and a metal magnetic thin film is formed on at least one opposing surface of the core pieces; and (b) a slit for accommodating the magnetic core. (c) a secondary glass portion that fixes the magnetic core in the slit;
Primary bonding temperature T_ for forming the primary glass part
1 (°C) is the following formula: T_1≦aW+b (where W is the thickness (μm) of the metal magnetic thin film,
a is -15 to -25 and b is 720 to 770. )
A method characterized in that the secondary bonding temperature T_2 for forming the secondary glass portion is 530° C. or less. (8) The method according to claim 7, wherein the metal magnetic thin film has a thickness of 1.5 to 5 μm.