JP2625905B2 - Bonding glass and magnetic head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bonding glass for fusing glass to a magnetic core or the like, and more particularly to a bonding glass suitable as a low-order fusing glass.

Further, the present invention relates to a magnetic head joined and integrated by a bonding glass.

[Summary of the Invention]

The present invention provides a bonding glass comprising a composition mainly composed of SiO ₂ , B ₂ O ₃ , Na ₂ O and / or K ₂ O, BaO, and by defining the composition range, a glass transition point of 560 ° C. or more. It is intended to lower the fusion temperature while maintaining the temperature.

Another object of the present invention is to provide a magnetic head having high reliability by using the above-mentioned bonding glass for joining magnetic cores made of an oxide magnetic material or a metal magnetic thin film.

[Conventional technology]

In general, a magnetic head joins and integrates magnetic cores made of an oxide magnetic material such as Mn-Zn ferrite, or magnetic cores obtained by combining these oxide magnetic materials and a metal magnetic thin film using a bonding glass. It is constituted by. Therefore, for example, the working gap portion of the magnetic head is configured by heating and melting glass to a high temperature higher than the melting point, pouring it between the magnetic cores, cooling it, and fusing the glass between these magnetic cores. You.
In a floppy disk drive or a hard disk drive, a magnetic head in which a non-magnetic member called a slider is further joined and integrated with glass to an integrated magnetic core, or the magnetic core is incorporated in the slider by glass melting A magnetic head embedded by wearing is used.

Thus, glass fusion is an essential element in a normal magnetic head, but in these magnetic heads,
The properties of the bonding glass used for fusion greatly affect its reliability.

For example, in a magnetic head that performs glass fusion twice, the first fusion glass must not start melting when performing the second fusion. The manufacture of a magnetic head of a so-called composite type for a hard disk will be described as an example. To manufacture such a magnetic head, first, a magnetic core is fused with high-melting glass so as to have a predetermined gap length (primary fusion). Wear). Next, the magnetic core that has been primarily fused is fitted into a groove provided in a slider material (for example, made of calcium titanate or the like), and is fixed by being fused (secondarily fused) with low-melting glass. . During this secondary fusion, 1
If the next fused glass is melted and the gap length, the track width, or the like is shifted, the reliability of the obtained magnetic head, such as the electromagnetic conversion characteristics, is greatly reduced.

Therefore, in particular, the primary fused glass needs to have a glass transition point higher than the fusion temperature after the secondary fusion.

[Problems to be solved by the invention]

Generally, the secondary fused glass has sufficient reliability (moisture resistance,
In order to secure hardness, etc., it is necessary to use a material having a fusion temperature of 530 ° C. or higher. Therefore, it is necessary to use a glass having a glass transition point of at least 530 ° C. as the primary fused glass, and it is safe to use a glass having a glass transition point of 560 ° C. or more.

However, such glasses typically have a fusion temperature of 80
When glass having a high fusion temperature of 0 ° C. or higher is used for the primary fusion, the magnetic properties of the metal magnetic thin film and the oxide magnetic material (ferrite) are deteriorated during the fusion, and the fusion jig of the fusion jig is not used. Problems such as a remarkable shortening of the service life occur.

Further, to produce such a glass, for example, 13
It is necessary to melt at a high temperature of about 50 to 1500 ° C and to keep the temperature at the time of drawing at about 1050 to 1250 ° C. However, the furnaces used for melting and keeping the temperature are severely deteriorated due to exposure to high temperatures, and frequent maintenance is required. Required, and at the same time the power usage increases.

As described above, the conventionally known bonding glass having a high glass transition point has many problems particularly with respect to the fusing temperature, and its improvement is awaited.

Therefore, the present invention has been proposed in view of the above-mentioned conventional circumstances, and provides a bonding glass having a low melting temperature and a low melting temperature despite having a glass transition point of 560 ° C. or more. With the goal.

Another object of the present invention is to provide a magnetic head having a high reliability, which can sufficiently exhibit the ability of a metal magnetic thin film or an oxide magnetic material, and has no gap length or track width deviation. I do.

[Means for solving the problem]

The present inventors have paid attention to the fact that glass does not begin to melt unless at least the glass transition point is exceeded, and while increasing the glass transition point, the viscosity of the glass suddenly decreases once the glass transition point is exceeded and immediately begins to melt. We made every effort to develop glass that is easy to fuse.

As a result, the conventional disadvantages were reduced by minimizing the proportion of SiO ₂ , increasing the amount of B ₂ O ₃ and BaO, which have the property of increasing the glass transition point, as much as possible, and adding an appropriate amount of Na ₂ O, which lowers the viscosity of the glass. They came to the knowledge that they could be improved.

The present invention has been completed based on such knowledge, and
O ₂ a wt%, B ₂ O ₃ b wt%, Na ₂ O and / or K ₂ O c wt%, BaO d wt%, Fe ₂ O ₃ and ZnO e wt%, and the composition range is 44 ≦ It is characterized in that a ≦ 60 10 ≦ b ≦ 25 12 ≦ c ≦ 20 10 ≦ d ≦ 150 ≦ e <14.

Further, the magnetic head of the present invention uses the above-mentioned bonding glass for joining magnetic cores.

Among the components of the bonding glass having the above composition, SiO ₂
Increases the glass transition point and the yield point and also increases the glass viscosity (and therefore the fusion temperature), but also has the role of improving the reliability (water resistance and corrosion resistance) of the glass and expanding the vitrification range. Fulfill.

Therefore, it is better to reduce the temperature as much as possible for the purpose of lowering the fusion temperature, but there is naturally an optimum range in terms of securing the glass transition point and the reliability. In the present invention, SiO ₂
Is 44 to 60% by weight.

When the content a of the SiO ₂ is less than 44% by weight, the glass transition point is less than 560 ° C., and the reliability is reduced. Conversely, SiO
_{2 If the} content a exceeds 60% by weight, the melting temperature of
Exceeds 300 ° C.

B ₂ O ₃ raises the glass transition point, but lowers the viscosity of the glass and lowers the fusion temperature. Therefore, the melting temperature is also lowered. In addition, B ₂ O ₃ tends to decrease the reliability of glass, although the range of vitrification is widened.

The content b of B ₂ O ₃ must be 10% by weight or more. If the content b is less than 10% by weight, it is difficult to reduce the melting temperature to 800 ° C. or lower or the melting temperature to 1300 ° C. or lower while maintaining the glass transition point at 560 ° C. or higher.
However, even if the content b of B ₂ O ₃ exceeds 25% by weight, the glass transition point cannot be further raised (the increase of the glass transition point due to B ₂ O ₃ is saturated), and SiO ₂ or BaO Is preferably reduced to less than this. Further, from the viewpoint of glass reliability and the like, it is preferable to suppress the content to 25% by weight or less.

Na ₂ O is a component that significantly increases the coefficient of thermal expansion of the obtained glass and lowers the fusion / melting temperature. However, if contained in a large amount, the reliability of the glass is lowered. Moreover, it is easy to deviate from the vitrification range, and drawing is difficult.

Therefore, here, the content c is set to 12 to 20% by weight. When the content c is less than 12 wt%, the thermal expansion coefficient becomes difficult to keep the 90 × 10 ^-7 ℃ ^-1 or higher, the melting temperature of 1300 ° C. or less, to achieve the fusing temperature 800 ° C. or less It becomes difficult. Conversely, if the content c of Na ₂ O exceeds 20% by weight, it becomes difficult to maintain the glass transition point at 560 ° C. or higher.

Note that part or all of the above Na ₂ O may be replaced with K ₂ O.

BaO raises the glass transition temperature without lowering the coefficient of thermal expansion. That is, while the above-described SiO ₂ and B ₂ O ₃ increase the glass transition point while lowering the coefficient of thermal expansion, BaO has a small decrease in the coefficient of thermal expansion. However, the fusion / melting temperature is increased. Therefore, the content d may be in the range of 10 to 15% by weight in consideration of the coefficient of thermal expansion, the glass transition point, and the like. When the BaO content d is less than 10% by weight, the glass transition point Tg can be maintained at 560 ° C. or higher, and the thermal expansion coefficient can be reduced to 9%.
It becomes difficult to keep the temperature at 0 × 10 ⁻⁷ ° C. ⁻¹ or more. BaO percentage
If it exceeds 15% by weight, the melting temperature of the glass will exceed 1300 ℃,
At the same time, precipitates are easily generated.

Fe ₂ O ₃ and ZnO are components for softening the reaction between ferrite or a metal thin film and glass, and from such a viewpoint,
It is added in a range of less than 14% by weight. Fe ₂ O ₃ and ZnO
Is more than 14% by weight, the glass transition point Tg is 56.
0 ° C or less.

The ratio of Fe ₂ O ₃ to ZnO is 40:60 to 7 by weight.
It is preferably 0:30. If the ratio of Fe ₂ O ₃ is less than 40, the effect of preventing the reaction can hardly be expected. Conversely Fe
_If the ratio of ₂ O ₃ exceeds 70, the ratio of the ferrite and the Fe ₂ O ₃ component used in the magnetic head becomes equal or more, so if this Fe ₂ O ₃ and ZnO precipitate in the glass, It may be a component having magnetism and may form a pseudo gap.

The bonding glass having the above composition has a glass transition point (temperature at which the coefficient of thermal expansion changes) of 560 to 600 ° C., and a yield point (temperature at which the glass shape does not return even when cooled when the temperature is further raised) 600 to 650 ° C. , Fusing temperature (working temperature, which depends on the flow) 700-800 ° C, melting temperature (production temperature) 12
The thermal expansion coefficient (value at 100 to 450 ° C.) is 90 × 10 ⁻⁷ by increasing or decreasing the content of Na ₂ O and K ₂ O.
110110 × 10 ⁻⁷ [° C. ⁻¹ ].

On the other hand, the magnetic head of the present invention is formed by joining the magnetic cores with the above-mentioned bonding glass.
Here, the joining of the magnetic cores refers to, for example, abutment of a pair of magnetic cores constituting a closed magnetic circuit, or a fixation of a recording / reproducing head portion and an erasing head portion like a magnetic head for a floppy disk. In the latter case, a center core made of a magnetic material or a non-magnetic material may be interposed therebetween.

In particular, in the case of a magnetic head for a floppy disk in which a guard material is bonded to both sides of a magnetic core or a magnetic head for a hard disk in which the magnetic core is embedded in a slider member, the bonding glass is used to bond the magnetic cores to each other. When used for fused glass, since the glass transition point of the glass is high, there is no fear that the primary fused glass is melted at the time of fusion after secondary fusion, which is preferable.

The magnetic core may be made of an oxide magnetic material such as ferrite alone, or may be made of a composite of a metal magnetic material such as an Fe-Al-Si alloy and an oxide magnetic material or a non-magnetic oxide material. It may be. Alternatively, the bonding glass used for bonding may be used as a gap spacer, or a gap spacer such as SiO ₂ may be previously formed on the bonding surface of the magnetic core, and the bonding glass may be used only for mechanical bonding. It may be used.

[Action]

In the bonding glass of the present invention, the ratio of SiO ₂ is suppressed, the ratio of B ₂ O ₃ and BaO for increasing the glass transition point is increased as much as possible, and B ₂ O ₃ and Na ₂ which have a property of reducing the viscosity of the glass are used. Since an appropriate amount of O (K ₂ O) is contained, the viscosity of the glass suddenly drops when the glass transition point is exceeded, even though the glass transition point is high (so-called short-circuiting), and the glass starts melting immediately. The glass is easy to wear.

The coefficient of thermal expansion is controlled by adjusting the content of Na ₂ O.

By using such a bonding glass for bonding magnetic cores made of an oxide magnetic material, a metal magnetic thin film, or the like, mechanical strength and reliability of the bonding are secured, and deterioration of magnetic properties due to fusion is suppressed. In particular, in a magnetic head such as a magnetic head for a floppy disk or a magnetic head for a hard disk, in which a plurality of glass fusion steps are performed, a low-order fusion step (for example, when there is a secondary fusion step). If the bonding glass is used in the secondary fusing step or the primary fusing step in the case where the first fusing step and the third fusing step are performed, there is a possibility that the glass may be melted in the subsequent fusing step. Therefore, there is no deviation in gap length, track width, or the like.

〔Example〕

 Hereinafter, the present invention will be described based on specific examples.

First, bonding glass (samples 1 to 3) was prepared by mixing SiO ₂ , B ₂ O ₃ , Na ₂ O, BaO, Fe ₂ O ₃ and ZnO in the proportions shown in Table 1.

For each of the obtained bonding glasses (samples 1 to 3), the coefficient of thermal expansion (100 to 500 ° C for samples 1 and 2;
(Sample 3 was measured at 100 to 450 ° C.) and the glass transition point was measured. The results are shown in Table 2.

Table 2 shows that all of the samples have a glass transition point of 560 ° C. or higher.

Then, the fusing temperature and the fusing temperature of these bonding glasses were examined next.

The fusing temperature varies depending on the fusing method, the shape of the adherend, the fusing atmosphere, and the like, but here, the temperature was determined by a normal magnetic head pouring method. That is, about 150 μm in width and about 120 in depth
Prepare a 40mm wide ferrite block with 20μm track width regulating grooves at 20μm intervals.Fill this with a ferrite block with only track width regulating grooves and a gap length of about 0.5μm. ,
A glass rod was inserted only into the glass groove, and the temperature at which all the grooves were filled with glass when heated at an inclination of about 20 ° was determined as the fusion temperature. The atmosphere for fusion is nitrogen 10
0%, and the distance from the glass groove to the tip of the ferrite block (the distance for flowing the glass) was about 3 mm.

The results are shown in FIG. 1 and FIG. For comparison, the bonding temperature and the melting temperature of a bonding glass used in a conventional magnetic head were measured as a comparative example. The composition of the bonding glass used as a comparative example is as shown in Table 3, and its glass transition point and thermal expansion coefficient are as shown in Table 4.

FIG. 1 shows the glass transition point of each glass on the vertical axis and the fusion temperature on the horizontal axis. FIG. 2 shows the melting temperature of each glass on the vertical axis and the glass transition point on the horizontal axis.

First, each glass of the comparative example is a primary fused glass for a magnetic head for a hard disk, a fused glass for a magnetic head for a video tape recorder, that is, a fused glass for a so-called metal head. , FIG. 2 shows a straight line. That is, when the glass transition point is high, both the fusion temperature and the melting temperature tend to be high. Particularly, when the glass transition point is 500 ° C. or more, the fusion temperature is 800 ° C. or more and the melting temperature is 1300 ° C. or more.

On the other hand, each of the samples to which the present invention is applied deviates greatly from the straight line, and both the fusion temperature and the melting temperature are significantly lower than those of the conventional glass having the same glass transition point. confirmed.

Then, a magnetic head for a hard disk was manufactured using the above-mentioned bonding glass.

As shown in FIGS. 3 and 4, the magnetic head for a hard disk is such that a magnetic head portion in which a pair of magnetic cores (1) and (2) are joined and integrated is embedded in a slider member (3). It is.

As shown in FIG. 5, in the magnetic head part, one magnetic core (1) has a metal magnetic thin film (1a) and a ferrite core part (1).
b), and the other magnetic core is made of ferrite alone, that is, a so-called metal-in-gap type configuration.

Here, an SiO ₂ film is formed as a gap material (4) on the joining interface between the magnetic cores (1) and (2), and the bonding glass (5) is formed of the magnetic cores (1) and (2).
Only the mechanical connection of (2) is achieved.

Samples 1 to 3 of the above samples were used as the bonding glass (5).

The above-described magnetic head is fitted in a slider member (3) provided with a notch corresponding to the shape of the magnetic head. Then, in the magnetic head portion, the vicinity of the sliding surface of the magnetic recording medium is shaved off in the medium running direction in order to regulate the track width, glass (6) is poured into the step portion, and the embedded portion is polished. The sliding surface of the magnetic recording medium is flush with the sliding surface (3a) of the slider member (3). The operating gap g is exposed on the sliding surface of the magnetic recording medium.

In the magnetic head having the above configuration, the magnetic core (1),
The bonding glass (5) for bonding (2) is the primary fused glass, and the glass (6) that flows into the step when fitted to the slider member (3) is the secondary fused glass.

Here, when a glass having a fusion temperature of 800 ° C. or more is used as the primary fusion glass, the SiO ₂ is significantly eroded by the glass.
On the other hand, the bonding glass (5) used in the present invention had a low fusion temperature in spite of a high glass transition point, so that the film erosion on the gap material (4) was small. In addition, the performance of the metal magnetic thin film (1a) was maximized without deteriorating the magnetic properties or peeling off the film.

Although some diffusion of metal into the glass occurred, it was possible to read the depth length because of the so-called I-type head.

Further, in such a magnetic head for a hard disk, it is necessary that the glass transition point of the bonding glass (5) as the primary fused glass is higher than the fusion temperature of the glass (6) as the secondary fused glass. Regardless of which sample is used, the glass transition point of the bonding glass (5) is 560 ° C. or higher, so that the range of choice of the material of the glass (6) as the secondary fusion glass is expanded, At the time of secondary fusion, the bonding glass (5) did not melt.

Then, next, the magnetic head portion was changed to a so-called composite ferrite head as shown in FIG. 6, and a magnetic head for a hard disk was similarly manufactured.

In this example, the ferrite magnetic cores (11), (1)
2) is bonded and integrated by the bonding glass (13), and the bonding glass (13) flows into the gap and is also used as a gap material. In addition,
Sample 1 was used for the bonding glass (13). Other configurations are the same as the previous example.

This example is also advantageous when secondary fusion is taken into account, but this glass cannot prevent the diffusion and erosion reaction with ferrite, so the front gap side where the gap length must be controlled is It is better not to use it if possible. In that case, it is effective to use an SiO ₂ film as a gap material as in the case of the above-mentioned metal-in-gap type. In addition, even if the glass is used only on the back side, it is possible to sufficiently prevent the gap at the fusion temperature at the time of secondary fusion glass fusion.

Next, an example in which the present invention is applied to a magnetic head for a floppy disk will be described.

As shown in FIG. 7, a magnetic head for a floppy disk has a magnetic core (21), (22) made of ferrite and magnetic cores (23), (24) joined and integrated to form a recording / reproducing head unit and an erasing unit. At the same time as configuring the head,
The recording / reproducing head unit and the erasing head unit are integrally fixed, and a guard material (25) made of ceramics or the like is joined to both sides in the running direction of the magnetic recording medium.

That is, the magnetic cores (21) and (22) and the magnetic cores (2
3) and (24) are joined and integrated by the primary fused glass (26), and the read / write head and erase head [magnetic core (2
2) and the magnetic core (23)] are fixed to each other with the secondary fused glass (27). Further, the guard material (25) is joined by the tertiary fused glass (28).

Here, Sample 3 which is a glass having the above-mentioned composition was used as the secondary fused glass (27).

By using the sample 3 for the secondary fused glass (27), the reliability of the fixed state of the recording / reproducing head and the erasing head is improved, and the material of the tertiary fused glass (28) is used. The range of choices has expanded.

In this example, the sample 3 was used for the secondary fused glass (27), but it is needless to say that the glass may be used for the primary fused glass (26). In this case, it is preferable to use the glass while taking advantage of the advantage that the glass transition point Tg is high, such as by using only the bonding on the back side in consideration of the reaction with ferrite.

As described above, specific examples of the present invention have been described.
It is needless to say that the present invention is not limited to these embodiments, and can be modified without departing from the spirit of the present invention. For example, the material, shape, dimensions, and the like of the magnetic core and the like can be appropriately changed.

〔The invention's effect〕

As is clear from the above description, the bonding glass of the present invention has a high glass transition point (560 ° C. or higher), a low fusion temperature and a low fusion temperature, and has high reliability and workability. Its practical value is great in satisfying the conflicting characteristics at the same time.

Further, the glass of the present invention can control the coefficient of thermal expansion by increasing or decreasing the content of Na ₂ O, and furthermore, Fe
By adding ₂ O ₃ and ZnO, it is possible to suppress the erosion diffusion reaction with the oxide magnetic material, which is very advantageous in actually manufacturing a magnetic head.

On the other hand, in the magnetic head of the present invention, a bonding glass having excellent properties such as a high glass transition point and a low fusion temperature is used for joining magnetic cores made of an oxide magnetic material, a metal magnetic thin film, and the like. Therefore, a magnetic head having high reliability can be obtained, and the temperature at the time of glass fusion can be suppressed low, so that deterioration of magnetic characteristics can be suppressed. In particular, in a magnetic head having a process of secondary fusion, tertiary fusion, etc., if the above-mentioned bonding glass is used for primary fusion, secondary fusion, etc., deviations in gap length, track width, etc. can be reduced. The magnetic head can be eliminated, and the selection of the glass material to be used in the subsequent fusion can be widened.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram plotting the glass transition point and the fusion temperature of Examples and Comparative Examples to which the present invention is applied.
The figure is a characteristic diagram plotting the glass transition point and the melting temperature of the examples and the comparative examples to which the present invention is applied. FIG. 3 is a schematic perspective view showing a configuration example of a magnetic head for a hard disk, FIG. 4 is an enlarged perspective view of a main part thereof, FIG. 5 is a schematic perspective view of a metal-in-gap type magnetic head section, FIG. 6 is a schematic perspective view of a magnetic head portion of a composite ferrite head type. FIG. 7 is a schematic plan view showing a configuration example of a magnetic head for a floppy disk. 1,2,11,12,21,22,23,24 Magnetic core 5,13 Bonding glass 26 Primary fused glass 27 Secondary fused glass 28 Tertiary fused glass

Claims (2)

(57) [Claims] (1) SiO ₂ a wt%, B ₂ O ₃ b wt%, Na ₂ O and / or
Or K ₂ O c weight%, BaO d weight%, Fe ₂ O ₃ and ZnO e weight%
A bonding glass having a composition range of 44 ≦ a ≦ 60 10 ≦ b ≦ 25 12 ≦ c ≦ 20 10 ≦ d ≦ 150 ≦ e <14. To 2. A junction between the magnetic core, SiO ₂ a wt%, B ₂
O ₃ b wt%, Na ₂ O and / or K ₂ O c wt%, BaO d wt%, Fe ₂ O ₃ and ZnO e wt% (provided that 44 ≦ a ≦ 60,10 ≦
A magnetic head using a bonding glass satisfying b ≦ 25, 12 ≦ c ≦ 20, 10 ≦ d ≦ 15, 0 ≦ e <14.