JPH06314407A - Fusing glass for magnetic head and magnetic head - Google Patents

Abstract

(57) [Summary] [Structure] Using a fused glass containing PbO, B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ and CoO in a predetermined composition ratio, for example, a head element 3 and sliders 5, 6 are used. The glass 38
Fuse together. [Effect] Even when the working temperature is set low, the fused glass is sufficiently softened, and it is possible to fuse the slider and the head element with strong bonding strength. Therefore, since the head element and the slider can be reliably joined and integrated without moving the fused glass fused in the preceding step of the glass fusion of the head element and the slider, reliability without track deviation and depth variation can be obtained. It is possible to obtain an excellent magnetic head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fused glass for a magnetic head, which is suitable for fusion-bonding a magnetic head element and a slider, for example, and a magnetic head using the fused glass.

[0002]

2. Description of the Related Art Conventionally, a magnetic head for recording / reproducing an information signal on a floppy disk or the like has a recording / reproducing magnetic gap and a pair of erasing magnetic gaps arranged on both rear sides of the recording / reproducing magnetic gap. A so-called tunnel erase type magnetic head is used. The recording / reproducing magnetic gap is for literally recording a signal on a floppy disk and reproducing the recorded signal. On the other hand, the erasing magnetic gap is for erasing only both ends of the recording signal so that even if the recording / reproducing magnetic gap deviates from the recording track of the floppy disk, a gap can be guaranteed between the data of adjacent tracks. Is.

As a magnetic head having such a magnetic gap for recording / reproducing and a magnetic gap for erasing, a composite magnetic head element in which a recording / reproducing head and an erasing head, which are separately manufactured, are joined and integrated with each other. It has been proposed that the composite head element and a floppy disk are sandwiched by a pair of sliders for ensuring contact.

[0004]

Here, in such a magnetic head, the joining of the members, that is, the joining of the core members respectively constituting the recording / reproducing head and the erasing head, the recording / reproducing head and the erasing are performed. The heads are bonded to each other, and the composite head element and the slider are usually bonded by glass fusion. These respective members are fused and integrated with each other by glass fusion, and at the same time, the voids on the joint surface, for example, the track width regulating grooves are filled with the fusion glass, and the mechanical strength is reinforced.

In the fused glass for joining and reinforcing these members, the coefficient of thermal expansion, the softening temperature, the fusing temperature,
Reactivity with core material, chemical durability, foamability, insulation resistance,
Color shade and the like are listed as selection criteria items, and fused glass having these appropriate characteristics is selected.

For example, the thermal expansion coefficient of the fused glass needs to be substantially the same as that of the ferrite that is the core material. If there is a large difference in the coefficient of thermal expansion between the fused glass and the core material, cracks will occur in the fused glass and the core material during glass fusion, and the deterioration of characteristics will be induced.

When the fused glass reacts with the core material, the interface between the fused glass and the core material is disturbed, the dimensional change of the core material, turbidity and cracks of the glass occur, and the precision such as the gap depth is improved. Since the size of the required portion changes, the fused glass is required to be one that does not react with the core material.

Further, in order to secure the reliability of the magnetic head, the fused glass is required to have excellent chemical durability such as water resistance and alkali resistance, and the fused glass is foamed by heating. If so, not only the adhesive strength is insufficient, but also the fused glass fused with bubbles is exposed on the sliding surface of the magnetic recording medium to form holes and deteriorate the contact characteristics with the floppy disk. It is also necessary that the glass is not foamable.

In addition, the fused glass is required to have a high circularity in cross section when formed into a rod shape. Fused glass is usually used for glass fusing in a rod shape, but if the circularity of the cross section is low, the fused glass will be supplied to the bonding portion in an amount different from the specified amount. , If the supply amount is too small, the glass will come off and the adhesive strength will be insufficient, or conversely, if the supply amount is too large, for example, the winding groove formed on the joint surface of the magnetic core half will be filled with glass and the required winding There is an inconvenience that a line space cannot be obtained.

In addition to the above characteristics, the fused glass must have appropriate softening temperature and fusing temperature in each glass fusing step. This is largely due to the fact that the magnetic characteristics of the core material are deteriorated if the temperature at the time of glass fusion is too high and the following reasons.

That is, for example, in the manufacture of a magnetic head having the recording / reproducing magnetic gap and the erasing magnetic gap, the magnetic core members are joined together, the recording / reproducing head and the erasing head are joined together, the composite head element and the slider are joined together. Are joined by the primary glass fusion process, the secondary glass fusion process,
The third glass fusion process is performed in different stages. At this time, if the temperature applied in the secondary glass fusing step and the third glass fusing step is higher than the softening temperature of the fused glass used in the glass fusing in the previous step, the glass fused in the previous step will move. Are displaced from each other, and, for example, a track shift or a change in the gap length is induced. From the viewpoint of avoiding such inconvenience, the working temperature in the primary glass fusing step, the secondary glass fusing step, and the third glass fusing step is such that the glass fusing temperature in the subsequent step is the glass fusing temperature in the previous step. When manufacturing a magnetic head for 2 MB, for example, 780 ° C., 760 ° C., 510 ° C.
On the other hand, when manufacturing a magnetic head for 4 MB, 70
The temperatures are set to 0 ° C, 600 ° C, and 480 ° C, respectively.

Therefore, the primary fused glass, the secondary fused glass, and the tertiary fused glass are required to have a softening temperature and a fusion temperature at which they are softened and fused at these working temperatures.

As described above, it is necessary for the fused glass to satisfy these characteristics, and various compositions-adjusted fused glasses have been tried and selected. However, among these characteristics, it is extremely difficult to select a fusing glass having a low-temperature fusing property such as softening and fusing at a low temperature of about 480 ° C. which is required for a third fusing glass for a 4 MB magnetic head. Is the reality.

That is, in the case of a fused glass containing a glass component having a low melting point, for example, PbO as a main component, the above-mentioned 5
Even at a low working temperature of about 10 ° C. or 480 ° C., the members are softened and the members can be glass-fused. However, glass components having a low melting point such as PbO generally have weak adhesive strength, and when the ratio in the fused glass exceeds 75% by weight, practical adhesive strength cannot be obtained, and the composite head element and the slider cannot be obtained. Induce peeling with.

Therefore, conventionally, a fused glass containing PbO in a proportion of 75% by weight or less has been used as the third fused glass, but since the melting point is not sufficiently low, it softens at the above-mentioned low working temperature. ， Fusion becomes insufficient and satisfactory adhesive strength cannot be obtained.

Therefore, the present invention has been proposed in view of such conventional circumstances, and it is possible to sufficiently soften and fuse even at a low working temperature, and to fuse members with a strong adhesive strength. An object is to provide glass and a magnetic head using the same.

[0017]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have conducted extensive studies and, as a result, when CoO was contained in the fused glass, it contained 75% by weight or more of PbO having a low melting point. It has been found that sufficient adhesive strength can be obtained even in the case of using the glass, and a fused glass excellent in both low-temperature fusion property and adhesive strength can be obtained.

The present invention has been completed based on these findings. That is, fused glass for a magnetic head of the present invention, PbO, B ₂ O _3, made of SiO _2, Al ₂ O ₃ and CoO, PbO 75 to 85 wt%, B ₂
O ₃ is 5 to 18 wt%, SiO ₂ is 0 to 10 wt%, A
1 _{2 to 3} wt% of Co _{2 and} 1 to ₃ wt% of CoO, and the total ratio of B ₂ O ₃ and SiO ₂ is 1
It is characterized in that it is 0 to 18% by weight.

Further, the magnetic head of the present invention is characterized in that the head element and the slider are glass-fused with the fused glass for a magnetic head having the above composition.

[0020]

[Action] a composite head element and the slider upon which glass fusing, PbO, B ₂ O _3, made of SiO _2, Al ₂ O ₃ and CoO, PbO 75 to 85 wt%, B ₂
O ₃ is 5 to 18 wt%, SiO ₂ is 0 to 10 wt%, A
1 _{2 to 3} wt% of Co _{2 and} 1 to ₃ wt% of CoO, and the total ratio of B ₂ O ₃ and SiO ₂ is 1
Using fused glass of 0 to 18% by weight, 510 ° C
Alternatively, the fused glass is sufficiently softened even at a low working temperature of about 480 ° C., and the core chip and the slider are fused with a strong adhesive strength.

The above fused glass is sufficiently softened and fused even at a low working temperature because PbO having a low melting point is contained in a proportion of 75% by weight or more. Further, even if PbO having a low melting point is contained in a proportion of 75% by weight or more, a strong adhesive strength can be obtained because CoO acts to give an adhesive strength to the fused glass. The mechanism of action of CoO for improving the adhesive strength of the fused glass is not clear. However, in the fused glass, when CoO is contained in the above range, the surface tension at the time of fusion becomes small and the core material ferrite. It is presumed that the fused glass comes to be uniformly wetted with respect to, and the fused glass contributes effectively to adhesion.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings. The present example is an example in which the fused glass of the present invention is applied to glass fusion of a slider and a composite head element including a recording / reproducing head and an erasing head.

As shown in FIG. 1, the magnetic head of this embodiment comprises a composite head element 3 and a pair of sliders 5 and 6 for ensuring contact with a floppy disk.

The composite head element 3 has a pair of rod-shaped center core portions 7 and 8 and a pair of side core portions 9 and 10 which are substantially L-shaped. The center core portions 7 and 8 are made of a magnetic material such as ferrite,
A track width regulating groove for regulating the track widths of a _first magnetic gap g ₁ and a second magnetic gap g ₂ described later is provided on the abutting surface with the side core portions 9 and 10. On the other hand, the side core portions 9 and 10 are also made of a magnetic material such as ferrite and are abutted with the center core portions 7 and 8 to form the first magnetic gap g ₁ or the second magnetic gap g ₂ on the abutting surface. Front part 9
a, 10a and coil winding leg portions 9b, 10b provided substantially orthogonal to the front portions 9a, 10a. The front portions 9a, 10a are provided with track width regulating grooves having the same shape as the track width regulating grooves provided in the center core portions 7, 8. On the other hand, the coil winding leg portions 9b and 10b are integrally formed with the front portions 9a and 10a as flat thin plates. Then, the center core portions 7 and 8 and the side core portions 9 and 1
0 means that the glass 36 is fused and integrated on the abutting surfaces to be integrated, and the track width regulating grooves formed on the abutting surfaces are filled with the fused glass to reinforce the mechanical strength. .

In the composite core chip 3, the center core portions 7 and 8 are fused to each other by glass 37, and the side core portions 9 and 10 are joined and integrated on the side surfaces thereof by fusion bonding of glass 36. ing. In this composite core chip 3, the center core portions 7 and 8 are
Is adhered by the glass 37, which is a non-magnetic material, so that magnetic interference is hindered, and as a result, a first magnetic recording / reproducing magnetic gap operates on the abutting surface of the center core portion 7 and the side core portion 9. Magnetic gap g
₁ is formed and operates as an erasing magnetic gap on the abutting surface of the center core portion 8 and the side core portion 10.
Magnetic gap g ₂ is formed.

Furthermore, the composite core chip 3 is
Usually, a back core (not shown) formed corresponding to the shape of the composite core chip 3 on the side opposite to the sliding surface of the magnetic recording medium.
However, a closed magnetic circuit is formed by contacting the coil winding leg portions 9b and 10b and the center core portions 7 and 8 and superposing them in a so-called stepped state. As a result, a magnetic head element having the _first magnetic gap g ₁ that operates as a recording / reproducing magnetic gap, that is, a recording / reproducing head 39,
A magnetic head element having a _second magnetic gap g ₂ that operates as an erasing magnetic gap, that is, an erasing head 40.
Is configured.

On the other hand, the pair of sliders 5 and 6 are provided in order to secure the contact characteristic with the floppy disk, and are provided on both sides of the composite head element 3 as blocks made of ceramic or the like in the form of a rectangular plane. The composite head element 3 is sandwiched in the thickness direction, and the glass head 38 is fused. Of these sliders 5 and 6, the slider width W ₂ of the slider 6 on the right side in FIG. 1 is larger than the slider width W ₁ of the other slider 5.

A surface 28 which is flush with the sliding surface 27 of the magnetic recording medium exhibited by the first magnetic gap g ₁ and the second magnetic gap g ₂ of the composite head element 3 of the sliders 5 and 6, An air inflow groove 30 and inclined surfaces 31 and 32 for improving the contact characteristics with the floppy disk are formed at 29. The surfaces of the sliders 5 and 6 facing the composite head element 3 have front portions 9a and 10a and center core portions 7 and 8 of the composite head element 3, respectively.
The front core 1 is sandwiched and serves as an adhesive surface when glass is fused.

The one slider 5 is provided with core reinforcing portions 33a, 33b, 33c for reinforcing the coil winding leg portions 9b, 10b and the center core portions 7, 8 of the composite head element 3, respectively. Has been. The core reinforcing portions 33a, 33b, 33c are formed by joining and integrating the center core portions 7, 8 and the coil winding leg portions 9b, 10b.
Is formed as a flat plate having substantially the same shape, and the length in the depth direction is the same. And
These core reinforcing portions 33a, 33b, 33c are composed of the center core portions 7, 8 and the coil winding leg portions 9b, 10 which face each other.
and b are in surface contact with each other.

Further, the other slider 6 is also provided with a core reinforcing portion (not shown) for reinforcing the coil winding leg portions 9b and 10b and the center core portions 7 and 8 of the composite head element 3, respectively. ing. These core reinforcements are
The length in the depth direction is the core reinforcing portions 33a, 33b,
The length is shorter than that of 33c, and only the proximal portions of the center core portions 7 and 8 and the coil winding leg portions 9b and 10b that are opposed to each other are supported. The core reinforcing portion is also in surface contact with the center core portions 7 and 8 and the coil winding leg portions 9b and 10b.

Further, the other slider 6 is provided with a plurality of support leg portions 35 serving as fixing portions when fixing the magnetic head completed by incorporating the front core 1, the back core 2, etc. to the gimbal. . These supporting leg portions 35 are formed to have a size sufficient to stably fix the magnetic head to the gimbal, and are integrally provided with the slider 6 on the half body side with respect to the core reinforcing portion.

The magnetic head having the above structure is basically manufactured by a three-step glass fusing process. That is, the recording / reproducing head 39 and the erasing head 40 are manufactured by fusing the glass 36 with the center core portions 7 and 8 and the side core portions 9 and 10 corresponding to the recording / reproducing head 39 and the erasing head 40, respectively. Primary glass fusing step, recording / reproducing head 39 and erasing head 40 are fused with glass 37 to manufacture composite head element 3. Secondary glass fusing step, composite head element 3 and sliders 5, 6 are made into glass 3
8 This is a tertiary glass fusion process for fusion to complete the magnetic head.

At this time, if the temperature applied in the secondary glass fusing step and the third glass fusing step is higher than the softening temperature of the fusing glasses 36 and 37 used in the glass fusing in the previous step, the previous step will be performed. The fused glasses 36 and 37 move to cause the members to be displaced from each other, and, for example, a track shift or a change in the gap length is induced. From the viewpoint of avoiding such inconvenience, the primary glass fusion step, the secondary glass fusion step,
The working temperature in the third glass fusing step is, for example, 7 when manufacturing a magnetic head for 2 MB so that the glass fusing temperature in the subsequent step is lower than the glass fusing temperature in the previous step.
When manufacturing a magnetic head for 4MB at about 80 ° C, 760 ° C, 510 ° C, 700 ° C, 600 ° C, 480 ° C
It is set to each degree.

Here, in this embodiment, as the fused glass used in the third glass fusion step, PbO, B was used.
₂ O ₃ , SiO ₂ , Al ₂ O ₃ and CoO,
PbO is contained in an amount of 75 to 85% by weight, B ₂ O ₃ is 5 to 18% by weight, SiO ₂ is 0 to 10% by weight, Al ₂ O ₃ is 1 to 4% by weight, and CoO is 1 to 3% by weight. And the total proportion of B ₂ O ₃ and SiO ₂ is 10 to 18% by weight.

Since the fused glass having such a composition contains PbO having a low melting point in a concentration of 75% by weight or more, it is sufficiently softened even at a low working temperature such as 510 ° C. and 480 ° C. to form a composite core chip. The slider and glass are fused together. Further, when PbO having a low melting point is contained in a proportion of 75% by weight or more, the adhesive strength of the fused glass is lowered, but in the above fused glass, such adhesive strength is suppressed by CoO, and the bonded composite The head element 3 and the sliders 5 and 6 are joined with sufficient strength without peeling or the like.

Therefore, in the above fused glass,
It is important that the ratio of PbO and CoO is within the above range.

In order to lower the melting point of the fused glass and improve the fluidity in the glass fusing process with PbO, P
Although it is necessary to contain bO in a proportion of 75% by weight or more, if the PbO content exceeds 85% by weight, the fused glass is not stabilized and devitrifies. Therefore, PbO must be contained in the range of 75 to 85% by weight.

On the other hand, in the fused glass containing PbO in an amount of 75% by weight or more, if the content of CoO in an amount of 1% by weight or more improves the adhesive strength, when the content of CoO exceeds 3% by weight, the fusion After attachment, bubbles will remain in the fused glass, and on the contrary, the adhesive strength will be extremely reduced.
Further, the bubbles remaining on the fused glass form holes on the sliding surface of the magnetic recording medium, and deteriorate the contact property with the magnetic recording medium. Therefore, CoO must be contained in the range of 1 to 3% by weight.

Of the glass components other than PbO and CoO, B ₂ O ₃ and SiO ₂ are essential components for forming a glass mesh. Of these, B ₂ O ₃ must be contained in a proportion of at least 5% by weight, and if it is less than 5% by weight, the glass will not stabilize and devitrify. But,
When B ₂ O ₃ is contained exceeds 18 wt%, the higher the melting point, since low-temperature fusibility is degraded, B ₂ O ₃ 5 to 18
It is contained in the range of% by weight. In addition, SiO _{2 is} also B ₂ O ₃
Similar to the above, it is an essential component for forming a glass network, but if it is contained in an amount of more than 5% by weight, it affects the melting point and deteriorates the low-temperature fusion property, so it is contained in an amount of 5% by weight or less. . Then, the total proportion of B ₂ O ₃ and SiO ₂ is set to 10 to 18% by weight in consideration of such low temperature fusion property and formation of glass network.

Al ₂ O ₃ is contained in order to improve the chemical durability, and its effect is exhibited by containing 1% by weight or more. However, the ratio is 4
If the content exceeds 10% by weight, the melting point of the fused glass becomes high and the low temperature fusion property deteriorates. Therefore, it is contained in the range of 1 to 4% by weight.

Next, the following experiment was conducted to confirm the effect of actually containing CoO in the fused glass.

First, PbO, CoO, SiO ₂ , B ₂ O
₃ , a predetermined amount of Al ₂ O ₃ is sampled and put into a platinum crucible,
A fused glass rod was produced by melt-mixing at a temperature of about 1000 ° C. for about 30 minutes to produce fused glass and drawing it. The proportion of CoO was changed to 0% by weight, 1% by weight, 2% by weight, 3% by weight and 4% by weight, and the proportion of glass components other than CoO was fixed as shown in Table 1. The obtained fused glass has a thermal expansion coefficient of 105 to 110 × 10.
^-7 ° C ^-1 , glass transition point is 340 to 350 ° C.

[0043]

[Table 1]

A composite core chip made of ferrite and a slider made of ceramic, each of which was made of various fused glasses having different CoO ratios, were heated at a temperature of 4 at a nitrogen atmosphere.
Glass was fused at a working temperature of 55 ° C., and the adhesive strength between the fused composite core chip and the slider was measured. In addition, as shown in FIG. 2, the adhesive strength is measured by sandwiching and fixing one slider 6 in a clamp 51, and applying a shearing load to the other slider 5 from the joint surface direction in this state by applying a load application means 52. It was carried out by measuring the applied load when the slider 5 was peeled from the head element 3. The relationship between the ratio of CoO in the fused glass and the adhesive strength is shown in FIG.

As can be seen from FIG. 3, the adhesive strength between the composite head element and the slider is improved as the proportion of CoO in the fused glass is increased. From this, it is possible to add Pb to the fused glass.
It was found that the inclusion of CoO together with O is effective in suppressing the decrease in adhesive strength due to PbO.
However, when the proportion of CoO exceeds 3% by weight, the adhesive strength is weakened conversely, so it was found that CoO needs to be contained in a proportion of 3% by weight or less.

The above description is an example of the case where the composite head element including the recording / reproducing head and the erasing head and the slider are glass-fused, but the fused glass for a magnetic head of the present invention is the same. Besides, it can be used for glass fusion of various head members, for example, when it is used for glass fusion of thin film magnetic head element and protective substrate, glass fusion of ferrite head element and slider To do.

That is, the thin film magnetic head is, for example, as shown in FIG.
As shown in FIG. 3, it has a thin film magnetic head element 61 and a protective substrate 62 laminated on the thin film magnetic head element 61.

In the thin-film magnetic head element 61, the lower magnetic core 63 and the upper magnetic core 64 have the insulating film 6 at the central portion.
The conductor coil 66 is sandwiched between the two. The upper magnetic core 64 is gradually narrowed between the lower magnetic core 63 and the upper magnetic core 64 by bending the sliding surface side of the magnetic recording medium toward the lower magnetic core 64 side.
A gap film 67 is interposed between the narrowed lower magnetic core and the upper magnetic core, whereby a magnetic gap g is formed. The rear end portion of the upper magnetic core 64 is bent toward the lower magnetic core 63 and is in direct contact with the lower magnetic core 63, thereby forming a closed magnetic circuit.

The protective substrate 62 is provided to protect the magnetic circuit portion of the thin film magnetic head element,
Glass 68 is fused onto the upper magnetic core 64 with a protective layer 65 in between.

As the fused glass for fusing the protective substrate 62 to the glass 68 on this thin film magnetic head element, the above-mentioned PbO,
When a fused glass containing B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ and CoO in a predetermined ratio is used, the thin film magnetic head element 61 and the protective substrate 62 have a strong adhesive strength even at a low working temperature. The glass 68 is fused to obtain a thin film magnetic head having excellent mechanical characteristics without deteriorating the magnetic characteristics of the thin film magnetic head element 61.

Further, FIG. 5 shows a magnetic head in which a ferrite head element 71 is mounted on a slider 72.

The ferrite head element 71 comprises a pair of magnetic core halves 7 made of an oxide magnetic material such as ferrite.
A closed magnetic circuit is formed by abutting 3,74 via the SiO ₂ gap film, and a magnetic gap g is formed between the abutting surfaces.

A winding groove 75 for winding the coil and a track width restricting groove for restricting the track width T _w of the magnetic gap g are provided in the middle of the abutting surfaces of the magnetic core halves 73, 74. It is formed at both ends of the magnetic gap g. The magnetic core halves 73, 74 are joined and integrated by fusing glass on the abutting surfaces in this manner, and the track width regulating grooves formed on the abutting surfaces are filled with the fused glass. By doing so, the mechanical strength is reinforced.

The slider 72 is formed as a rectangular block in plan view, and a head mounting groove 76 into which the ferrite head element 71 is mounted is formed on one side surface thereof. Then, inclined surfaces 77, 78 and the like are formed on the surface of the mounted ferrite head element 71 on the magnetic gap g side.

The ferrite head element 71 and the slider 72 are mounted and joined by PbO, B ₂ O ₃ , SiO ₂ and Al.
_{When the} glass is fused by a fused glass containing ₂ O ₃ and CoO in a predetermined ratio, the ferrite head element 71 and the slider 72 are strongly bonded to each other even when the working temperature is set low. It is possible to obtain a magnetic head which can be fused and has excellent mechanical characteristics without moving the fused glass that fuses the magnetic core halves to each other and without deteriorating the magnetic characteristics of the ferrite head element 71. .

[0056]

As is clear from the above description, the fused glass of the present invention contains PbO, B ₂ O ₃ , SiO ₂ and Al.
_{Since 2} O ₃ and CoO are contained at a predetermined ratio, the head element and the slider can be glass-fused with a strong adhesive strength even when the working temperature is set low.

Therefore, according to the present invention, the head element and the slider can be surely joined and integrated without moving the fused glass fused in the step prior to the glass fusion of the head chip and the slider. It is possible to obtain a magnetic head having excellent reliability, which is free from track deviation and depth variation.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an example of a magnetic head to which the present invention is applied.

FIG. 2 is a schematic side view showing the configuration of an adhesive strength measuring device for measuring the adhesive strength between a magnetic head element fused with glass and a slider.

FIG. 3 is a characteristic diagram showing the relationship between the ratio of CoO contained in the fused glass and the adhesive strength.

FIG. 4 is a schematic cross-sectional view of a main part showing another example of a magnetic head to which the present invention is applied.

FIG. 5 is a schematic side view showing still another example of a magnetic head to which the present invention is applied.

[Explanation of symbols]

 3 ... Composite head element 5, 6 ... Slider

Claims (2)

[Claims] 1. PbO, B ₂ O ₃ , SiO ₂ , Al ₂ O
₃ and CoO, PbO is 75 to 85% by weight,
B ₂ O ₃ is 5 to 18% by weight, SiO ₂ is 0 to 10% by weight, Al ₂ O ₃ is 1 to 4% by weight, CoO is 1 to 3% by weight.
The fused glass for a magnetic head, characterized in that the total content of B ₂ O ₃ and SiO ₂ is 10 to 18% by weight. 2. A magnetic head, wherein the head element and the slider are glass-fused with the fused glass for a magnetic head according to claim 1.