JP2570791B2 - 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, a slider member, and the like, and further relates to a magnetic material bonded and integrated from a bond glass. It concerns the head.

[Summary of the Invention] The present invention provides a bonding glass comprising PbO, SiO ₂ , B ₂ O ₃ , Bi ₂ O
₃ , a composition composed of Na ₂ O and / or K ₂ O, Fe ₂ O ₃ and ZnO, and by regulating the composition range, the thermal expansion coefficient is controlled and, at the same time, erosion and diffusion to the oxide magnetic material It is intended to suppress the reaction.

Further, the present invention intends 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 between the magnetic core and the slider member. is there.

[Conventional technology]

In general, a magnetic head is configured by joining and integrating magnetic cores made of an oxide magnetic material such as Mn-Zn ferrite using bonding glass. For example, the working gap portion of the magnetic head is configured by heating and melting glass to a high working temperature above the melting point, pouring it between magnetic cores, then cooling, and fusing glass between these magnetic cores. . 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.

As described above, glass fusion is an essential element in ordinary magnetic heads, but in these magnetic heads, the thermal expansion coefficient of the bonding glass used for fusion is the thermal expansion coefficient of the oxide magnetic material of the magnetic core. When the magnetic core and the like are greatly different from each other, residual stress is accumulated when the magnetic core and the like are joined, and glass cracks and the like are easily generated. Generally, oxide magnetic materials such as Mn-Zn ferrite having a high magnetic flux density have a large thermal expansion coefficient of 120 × 10 ^{−7 to} 140 × 10 ⁻⁷ [° C. ⁻¹ ] at 100 to 350 ° C. (normal magnetic heads). Mn-Zn ferrite used in 10
0 × 10 ^{−7 to} 120 × 10 ⁻⁷ [° C. ⁻¹ ], and therefore, the glass to be bonded must have a large coefficient of thermal expansion. That is, in order to join the magnetic cores made of these oxide magnetic materials, it is necessary to use a bonding glass having a thermal expansion coefficient of about 85 × 10 ^{−7 to} 125 × 10 ⁻⁷ [° C. ⁻¹ ].

However, a high coefficient of thermal expansion (in particular, a coefficient of thermal expansion α ≧ 11
0 × 10 ^-7 ℃ ^-1 or more], since low-melting glass contains a large amount of lead and alkali components, its water resistance and hardness are remarkably inferior to high-melting glass. When a magnetic head is to be manufactured in this way, there arises a problem that glass elution and glass cracks frequently occur.

In addition, when a magnetic core made of ferrite is glass-bonded, disturbance at the ferrite interface is often observed at the butting portion of the working gap and at the periphery thereof. This is because the bonding glass erodes the ferrite, and conversely, the ferrite diffuses into the bonding glass.

When such an erosion-diffusion reaction occurs, when the degree of the reaction is large, the electromagnetic conversion characteristics of the magnetic head are significantly degraded. It becomes difficult to read.

Therefore, it is preferable to suppress such erosion-diffusion reaction as much as possible. However, conventional glass having a large coefficient of thermal expansion contains a large amount of alkali components, so that erosion-diffusion reaction is extremely large, which is disadvantageous in this respect.

[Problems to be solved by the invention]

As described above, the conventional bonding glass has many problems in terms of thermal expansion coefficient, reliability, erosion-diffusion reaction to the oxide magnetic material, and the like, and improvement thereof has been awaited.

Therefore, the present invention has been proposed in view of such conventional circumstances, and it is possible to control the coefficient of thermal expansion in accordance with the magnetic core made of an oxide magnetic material, and to provide a bonding glass with a small erosion diffusion reaction. The purpose is to provide. Another object of the present invention is to provide a bonding glass having a low melting point and high hardness and high water resistance.

A further object of the present invention is to provide a magnetic head which can sufficiently exhibit the capability of an oxide magnetic material, has excellent electromagnetic conversion characteristics, and has high reliability.

[Means for solving the problem]

The present inventors have conducted intensive studies over a long period of time to achieve the above object, and found that Na ₂ O or K ₂ O is effective for controlling the thermal expansion coefficient, and Fe ₂ O ₃
In addition, the inventors have found that ZnO is effective, and have completed the present invention.

That is, the bond glass of the present invention comprises PbO a wt%, SiO ₂ b wt%, B ₂ O ₃ c wt%, Bi ₂ O ₃ d wt%, Na ₂ O and / or K ₂ O e wt%, Fe ₂ O ₃ and ZnO f wt%,
The composition range is 45 ≦ a ≦ 65 13 ≦ b ≦ 266 6 ≦ c ≦ 95 5 ≦ d ≦ 80 <e ≦ 115 ≦ f ≦ 8.

Also, the magnetic head of the present invention can be used for joining magnetic cores made of an oxide magnetic material or joining a magnetic core made of an oxide magnetic material to a slider member by using PbO a weight%, Si
O ₂ b wt%, B ₂ O ₃ c wt%, Bi ₂ O ₃ d wt%, Na ₂ O and / or K ₂ O e wt%, Fe ₂ O ₃ and ZnO f wt% (however, 45 ≦ a ≤
65,13 ≦ b ≦ 26,6 ≦ c ≦ 9,5 ≦ d ≦ 8,0 <e ≦ 11,5 ≦ f ≦
8) A bonding glass is used.

In bonding glass having the above composition, oxide (Pb
O) is a component for lowering the melting point of glass, and its composition ratio is increased or decreased in order to control the working temperature of the obtained bonding glass. However, if the PbO content is less than 45% by weight, the working temperature exceeds 620 ° C., for example, the SiO ₂ film serving as a gap material is easily eroded by the glass. Conversely, if the PbO content exceeds 65% by weight, the water resistance, The content of PbO is preferably set in the range of 45 to 65% by weight because alkalinity is deteriorated. In particular, since the grinding water used when processing the magnetic head is alkaline, the water resistance and alkali resistance of the glass are important.

Also, SiO ₂ is a component that extends the vitrification range,
In addition to increasing the melting point of the glass, the reliability (water resistance, alkali resistance, etc.) of the glass is improved. This SiO ₂
Also, from the viewpoints of working temperature, reliability and the like, the content is preferably in the range of 13 to 26% by weight. When the content of SiO ₂ is less than 13% by weight, the water resistance of the obtained glass is reduced.
Deterioration of alkali resistance and abrasion resistance. Also, it is easy to deviate from the vitrification range, and it becomes difficult to draw due to crystallization,
Wetting property deteriorates. Conversely, if the content of SIO ₂ exceeds 26% by weight, the fusing temperature exceeds 620 ° C., and the erosion of the gap material also becomes a problem.

B ₂ O _{3 is} also a component that widens the vitrification range, and reduces viscosity and improves wettability. For example, reducing the viscosity of glass with PbO will increase the coefficient of thermal expansion, but B ₂
O ₃ is a unique substance that lowers the viscosity without increasing the coefficient of thermal expansion. However, if the content of B ₂ O ₃ is less than 6% by weight, the obtained glass is crystallized, drawing is difficult, and the wetting property is deteriorated. Because it is easier to promote erosion to
It is preferable to set within the range of 6 to 9% by weight.

Bi ₂ O ₃ is a component similar to PbO, but has a property of lowering the fusion / dissolution temperature than PbO. The composition range of this Bi ₂ O ₃ is 5 to 8% by weight. If the content of Bi ₂ O ₃ is less than 5% by weight, the working temperature exceeds 620 ° C. Conversely, Bi ₂ O ₃
If the content exceeds 8% by weight, the wetting properties of the obtained glass become too good, which facilitates the erosion of ferrite and deteriorates the water resistance and alkali resistance of the glass.

Na ₂ O is a component that significantly increases the coefficient of thermal expansion of the obtained glass and lowers the melting point. However, when 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. In particular, when the content of Na ₂ O exceeds 11% by weight, the water resistance and alkali resistance of the glass are deteriorated, and the glass is crystallized, drawing becomes difficult, and the wetting property is deteriorated. It is preferable to suppress it. Also, the thermal expansion coefficient of the glass can be controlled by increasing or decreasing the content of Na ₂ O,
If it is not contained at all, the compatibility with ferrite will be poor. Therefore, the content e of Na ₂ O is set to 0% by weight <e ≦ 11% by weight. In this case, part or all of the above Na ₂ O may be replaced with K ₂ O.

Fe ₂ O ₃ and ZnO are components for preventing reaction with ferrite. If the total amount of Fe ₂ O ₃ and ZnO is less than 5% by weight, the diffusion of ferrite into glass or the Glass erosion to the surface occurs. Therefore, the glass is eroded at the ferrite interface, and chipping around the working gap is increased. Conversely, if the total amount of these components exceeds 8% by weight, these components are likely to precipitate in the glass. Many of these precipitates are generated around the ferrite constituting the working gap, which hinders the working such as the gap length appears to be shorter than the actual one or the edge is not sharp. In addition, the precipitates may cause uneven wear and dropout of the magnetic head. Therefore, the total amount f of these is set to 5 ≦ f ≦ 8% by weight.

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 395 to 435 ° C., and a yield point (temperature at which the glass shape does not return to a higher temperature if cooled down) 435 to 475 ° C. , Fusing temperature (working temperature, which depends on the flow) 550-620 ° C, melting temperature (production temperature) 11
00 to 1200 ° C., and by increasing or decreasing the content of Na ₂ O and K ₂ O, the coefficient of thermal expansion (the coefficients of thermal expansion described herein are values at 100 to 350 ° C. ) Is 85 × 10 ^-7
~ 125 × 10 ^-7 [° C n ^-1 ].

On the other hand, the magnetic head of the present invention is formed by joining the magnetic cores or the magnetic core and the slider member. Here, the joining of the magnetic cores means, for example, a pair of magnetic cores forming a closed magnetic circuit. These include abutment between the recording and reproducing heads and an erasing head, such as 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.

The magnetic core may be a single oxide magnetic material such as ferrite, or may be 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. Since the present invention has a great object of preventing the erosion-diffusion reaction between ferrite and glass, it is particularly effective when the magnetic core is an oxide magnetic material. Further, the bonding glass used for the bonding may be used as a cap spacer, or a gap spacer such as SiO ₂ may be previously formed on the bonding surface of the magnetic core, and the glass is used only for mere mechanical bonding. You may make it.

On the other hand, the joining between the magnetic core and the slider member is performed by joining a guard material to a magnetic core having a closed magnetic path such as a magnetic head for a floppy disk or embedding the magnetic core in a slider member such as a magnetic head for a hard disk. And so on. However, in this case, the glass transition point of the glass used for joining the magnetic cores is preferably higher than the fusion temperature of the bonding glass.

[Action]

PbO, SiO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , Na ₂ O and / or K ₂ O, Fe ₂ O ₃ and Z
In a glass made of nO, an increase or decrease in the content of Na ₂ O (K ₂ O) greatly affects an increase or decrease in the thermal expansion coefficient of the glass. That is, by selecting the content of Na ₂ O (K ₂ O) according to the thermal expansion coefficient of the magnetic core made of an oxide magnetic material, the thermal expansion coefficient of the glass is controlled to an optimum value. Also, Fe
By mixing ₂ O ₃ and ZnO, the erosion diffusion reaction on the oxide magnetic material is suppressed. In addition, an increase in the content of SiO ₂ restores the reduced reliability and deviation from the vitrification range with the formulation of Na ₂ O (K ₂ O).

By using such glass for joining magnetic cores made of an oxide magnetic material or between a magnetic core made of an oxide magnetic material and a slider material, residual stress due to fusion is suppressed, and the mechanical strength and reliability of the joining are reduced. Is secured. At the same time, turbulence and erosion at the interface between the oxide magnetic material and the glass are suppressed, the electromagnetic conversion characteristics are secured, and the gap length can be accurately grasped by an automatic gap length measuring device or the like.

〔Example〕

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

First, PbO, SiO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , Na ₂ O, Fe ₂ O ₃ and ZnO were mixed in the proportions shown in Table 1 to form a bonding glass (sample 1).
~ Sample 4) was produced.

About each obtained bond glass (sample 1-sample 4), the thermal expansion coefficient (100-350 ° C) and the glass transition point were measured. The results are shown in Table 2.

Table 2 shows that the coefficient of thermal expansion of the obtained glass changes according to the content of Na ₂ O. Also, the working temperatures of the obtained glasses are almost the same.

As described above, in the bonding glass of the present invention, the fusion temperature can be kept constant and the coefficient of thermal expansion can be changed. Therefore, by fusing with these glasses, the magnetic material is affected only by the coefficient of thermal expansion of the glass. Can be measured for the change in magnetic properties. Therefore, the optimum coefficient of thermal expansion of the bonding glass used for the magnetic head can be selected by using this.

In this way, a bonding glass having an optimum coefficient of thermal expansion was selected, and a magnetic head was manufactured.

For example, as shown in FIG. 1, a single crystal ferrite material [Mn-Zn ferrite having a high coefficient of thermal expansion. Thermal expansion coefficient 13
5 × 10 ⁻⁷ ° C. ⁻¹ ] bonding core (1), (2) produced by applying the present invention to a bonding glass (3) [sample
3: Gap fusion was performed using a thermal expansion coefficient of 115 × 10 ^-7 ° C ^-1 ] to produce a VTR head for high-density recording and reproduction. There was no elution due to dissolution or grinding stress.

Also, the magnetic cores (1) and (2) around the operating gap g
Was observed with an optical microscope, but almost no disturbance or erosion of the interface due to the reaction between the ferrite and the glass was found.

Similarly, when the sample 3 was used to fuse a magnetic core made of a polycrystalline ferrite material having a high coefficient of thermal expansion (coefficient of thermal expansion: 130 × 10 ⁻⁷ ° C. ⁻¹ ) at the working gap, glass elution was also observed. A magnetic head without glass cracks was obtained.

Therefore, next, a VTR that regulates the gap length only with the SiO ₂ film
Prototype the head.

The structure of the prototype magnetic head is as shown in FIGS. 2 and 3, and the magnetic cores (11) and (12) are made of ferrite having a coefficient of thermal expansion α = 110 × 10 ⁻⁷ ° C. ^−1. I have. The bonding interface between these magnetic cores (11) and (12) is SiO ₂
The film (13) is formed on the bonding glass (1
4) Mechanical fixing is performed, and the bonding glass (14) is filled in a track width regulating groove for defining the track width of the working gap so as to ensure contact with the magnetic recording medium.

In the magnetic head having such a configuration, when the sample 1 was used as the bond glass (14), not only did the erosion of both ends of the SiO ₂ film (13) disappear, but also the glass at the ferrite interface around the both ends. There was no disturbance or erosion due to the reaction.

On the other hand, when the conventionally used high melting point glass was used, both ends of the SiO ₂ film (13) were necessarily eroded by the glass.

The bonding glass of the present invention can be used not only for joining magnetic cores, but also for joining a magnetic core made of an oxide magnetic material and a slider member made of ceramics or the like.

Therefore, a magnetic head for a hard disk in which a magnetic core is embedded in a slider member was prototyped.

FIG. 4 and FIG. 5 show the structure of a magnetic head for a prototype hard disk. The magnetic head for a hard disk includes a slider member formed by joining and integrating a pair of magnetic cores (21) and (22). (23) It is embedded inside.

That is, a notch corresponding to the magnetic head portion is provided in the slider member (23), and the magnetic core (21),
(22) is fitted. In the magnetic head portion, the vicinity of the sliding surface of the magnetic recording medium is cut off along the medium running direction in order to regulate the track width, and glass (25) is poured into the step portion (24). And
The embedded portion is polished, and the sliding surface of the magnetic recording medium of the magnetic head portion is slid on the sliding surface (23a) of the slider member (23).
The operating gap g is exposed on the sliding surface of the magnetic recording medium.

Therefore, the gap material (26) of the operating gap g is 1
Next fused glass, glass (2
5) is the secondary fused glass.

In this magnetic head, when the bonding glass having the above-described composition is used for the glass (25), a magnetic head having no cracks and high reliability can be obtained. Nature was also secured. In addition, the magnetic core (2
Carefully observing the area around 1) and (22), almost no interface disturbance or erosion due to the reaction between ferrite and glass was found.

In such a magnetic head for a hard disk, it is necessary that the glass transition point of the gap material (26) as the primary fusion glass is higher than the fusion working temperature of the glass (25) as the secondary fusion glass. Since the glass (25) has a low melting point, the range of choice of the gap material (26) could be expanded.

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 materials, shapes, dimensions, etc. of the magnetic core and the slider member can be changed as appropriate.

〔The invention's effect〕

As is clear from the above description, since the bonding glass of the present invention contains Na ₂ O or K ₂ O and compensates for the reliability degradation by SiO ₂ , the thermal expansion coefficient is set to an optimum value. Despite the choice, it is possible to maintain the fusion temperature (working temperature) at a constant temperature to ensure water resistance and alkali resistance. Further, since the glass of the present invention contains Fe ₂ O ₃ and ZnO, the erosion-diffusion reaction with the oxide magnetic material can be significantly suppressed.

On the other hand, the magnetic head of the present invention has an optimum thermal expansion coefficient for joining magnetic cores made of an oxide magnetic material or joining a magnetic core and a slider member, and has a low melting point, high hardness, and high water resistance. Since a bonding glass having excellent properties such as properties is used, it is possible to obtain a highly reliable magnetic head free of glass cracks and glass elution. Also, since the bonding glass fusing operation temperature to be used is relatively low and constant at 530 to 620 ° C., even if an SiO ₂ film or the like is used as the gap regulating material, it does not erode.

In addition, ferrite erosion by bonding glass,
Since no diffusion occurs, a magnetic head having excellent electromagnetic conversion characteristics can be obtained.

Prevention of erosion and diffusion of ferrite is effective in accurately grasping the gap length, and the magnetic head of the present invention can accurately read the gap length by, for example, an automatic gap length measuring device.

[Brief description of the drawings]

1 to 5 each show an embodiment of a magnetic head to which the present invention is applied. FIG. 1 is a schematic perspective view of a ferrite head, and FIG. 2 is a perspective view of a ferrite head using an SiO ₂ film as a gap material. FIG. 3 is an enlarged plan view of a sliding surface of the magnetic recording medium, FIG. 4 is a schematic perspective view of a magnetic head for a hard disk, and FIG. 5 is an enlarged perspective view of a main part thereof. 1,2,11,12,21,22 …… magnetic core 3,14 …… bonding glass 25 …… glass

Claims (3)

(57) [Claims] (1) PbO a weight%, SiO ₂ b weight%, B ₂ O ₃ c weight%,
Bi ₂ O ₃ d wt%, Na ₂ O and / or K ₂ O e wt%, Fe ₂ O ₃ and Z
a bonding glass having a composition range of 45 ≦ a ≦ 65 13 ≦ b ≦ 266 6 ≦ c ≦ 95 5 ≦ d ≦ 80 0 <e ≦ 115 5 ≦ f ≦ 8 . 2. A method for joining PbO a weight%, SiO ₂ b weight%, B ₂ O ₃ c weight%, Bi ₂ O ₃ d
Weight%, Na ₂ O and / or K ₂ O e weight%, Fe ₂ O ₃ and ZnO f weight% (however, 45 ≦ a ≦ 65,13 ≦ b ≦ 26,6 ≦ c ≦ 9,5 ≦ d ≦
8. A magnetic head using a bonding glass consisting of 8,0 <e ≦ 11,5 ≦ f ≦ 8). 3. A method for joining a magnetic core made of an oxide magnetic material to a slider member, wherein PbO a weight%, SiO ₂ b weight%, B ₂ O ₃ c weight%, Bi ₂ O ₃ d weight%, Na ₂ O And / or K ₂ O e weight%, Fe ₂ O ₃
And ZnO f weight% (provided that 45 ≦ a ≦ 65,13 ≦ b ≦ 26,6 ≦ c
A magnetic head characterized by using a bonding glass which satisfies ≦ 9,5 ≦ d ≦ 8,0 <e ≦ 11,5 ≦ f ≦ 8).