JPH0764584B2 - Bonding glass for magnetic head - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bonding glass for a magnetic head used for fusing ferrite, ferromagnetic metal material, etc., and is suitable for forming a gap of a magnetic head, for example. The present invention relates to various bonding glasses.

[Outline of Invention]

The present invention uses a bonding glass for a magnetic head as PbO, Si.
The glass composition containing O ₂ , B ₂ O ₃ , Bi ₂ O ₃ and Na ₂ O is intended to control the coefficient of thermal expansion, and at the same time, to secure reliability and working temperature.

[Conventional technology]

Generally, a magnetic head is formed by bonding and integrating magnetic cores made of an oxide magnetic material such as Mn-Zn ferrite or a composite of these oxide magnetic materials and a metal magnetic material such as Sendust using bonding glass. Composed.
For example, the working gap part of the magnetic head is constructed by heating and melting the bonding glass to a working high temperature above the melting point, pouring it between the magnetic cores, and then cooling it to fuse the glass between these magnetic cores. To be done.

Such bonding glass is required to have strict characteristics in terms of water resistance, corrosion resistance, wear resistance, bonding strength, etc. For example, Japanese Patent Application Laid-Open No. 61-101432 discloses bonding containing PbO, SiO ₂ or the like as a main component. Glass has been proposed.

By the way, if the thermal expansion coefficient of the bonding glass for a magnetic head is significantly different from that of an oxide magnetic material or a metallic magnetic material,
It has a drawback that residual stress is accumulated when the magnetic cores are joined and glass cracks are likely to occur.

Therefore, the bonding glass for bonding oxide magnetic materials such as ferrite and magnetic metal materials has a coefficient of thermal expansion of 90 × in order to match the coefficient of thermal expansion with these adherends.
It is preferable to use one having a temperature of about 10 ^{−7 to} 130 × 10 ⁻⁷ [° C. ⁻¹ ].

However, in general, the larger the coefficient of thermal expansion of glass, the lower the melting point tends to be, and the coefficient of thermal expansion of 110
It was impossible to fabricate a precise magnetic head with glass having a temperature of × 10 ^-7 [° C ^-1 ] or more. This is because the low melting point glass has poor reliability, is significantly inferior in water resistance and hardness to the high melting point glass, and has a problem that glass elution and glass cracks frequently occur during magnetic head processing. .

[Problems to be solved by the invention]

As described above, the conventional bonding glass has many problems in terms of the coefficient of thermal expansion, reliability, etc., and its improvement has been awaited.

Therefore, the present invention has been proposed in view of such a conventional situation, and the thermal expansion coefficient can be controlled according to the material of the magnetic core, and at the same time, the softening temperature and the bonding capable of securing reliability can be secured. Intended to provide glass.

[Means for solving problems]

The present inventors have completed the present invention focusing on the fact that Na ₂ O is effective in controlling the coefficient of thermal expansion,
It is composed of PbO a% by weight, SiO ₂ b% by weight, B ₂ O ₃ c% by weight, Bi ₂ O ₃ d% by weight, Na ₂ O e% by weight, and its composition range is 49 ≦ a ≦ 69 14 ≦ b ≦ 28. It is characterized in that 6 ≦ c ≦ 10 5 ≦ d ≦ 8 0 ≦ e ≦ 12.

In the bonding glass having the above composition, lead oxide (Pb
O) is a component that lowers 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 49% by weight, the working temperature will exceed 600 ° C, while if the PbO content exceeds 69% by weight, the working temperature will be less than 550 ° C and the water resistance of the glass obtained will be poor. The amount is preferably in the range of 49 to 69% by weight. For example, when the bonding glass of the present invention is used for bonding a magnetic core having a sendust core portion, the heat treatment of the sendust core is performed at the same time as glass fusion, so that the glass fusion work temperature is 550 to 600 ° C.
And have to.

In addition, SiO ₂ is a component that widens the vitrification range, raises the melting point of the glass, and improves the reliability (water resistance, corrosion resistance, etc.) of the glass. The content of this SiO ₂ is also preferably in the range of 14 to 28% by weight from the viewpoint of working temperature and the like. If the SiO ₂ content is less than 14% by weight, the working temperature will be less than 550 ° C, and the water resistance, corrosion resistance, and abrasion resistance of the resulting glass will deteriorate. In addition, crystallization becomes difficult to draw and the wetting property deteriorates.
If the SiO ₂ content exceeds 28% by weight, the working temperature will be 600 ° C.
, And the wettability deteriorates.

B ₂ O _{3 is} also a component that widens the vitrification range, and lowers the viscosity and improves the wettability. For example, decreasing the viscosity of glass with PbO increases the coefficient of thermal expansion, but B ₂ O ₃
Is a unique substance that reduces 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 and drawing is difficult and the wettability deteriorates. If it exceeds 10% by weight, the wettability becomes too good. As the erosion of ferrite increases,
It is preferably set within the range of 10 wt%.

Bi ₂ O ₃ is a component similar to PbO, but has the property of lowering the viscosity of glass than PbO. The composition range of Bi ₂ O ₃ is 5 to 8% by weight. If the Bi ₂ O ₃ content is less than 5% by weight, the working temperature exceeds 600 ° C and the wettability of the glass deteriorates. On the other hand, when the content of Bi ₂ O ₃ exceeds 8% by weight, the wettability of the glass to be obtained becomes too good, and there is a risk of eroding ferrite and the like.

Na ₂ O is a component that greatly increases the thermal expansion coefficient of the obtained glass, but if it is contained in a large amount, it lowers the reliability of the glass and lowers the melting point. Moreover, it is easy to deviate from the vitrification range, making it difficult to draw. Therefore, in the present invention,
When the content of Na ₂ O is increased, the content of Si ₂ O is also increased at the same time to increase the melting point to secure a predetermined melting point, widen the vitrification range, and improve the reliability. However, if the content of Na ₂ O exceeds 12% by weight, the water resistance and corrosion resistance of the glass will deteriorate, and since the glass will crystallize and the wire drawing will become difficult, and the wettability will deteriorate.
It is preferable to suppress it to the following. Further, the coefficient of thermal expansion of glass can be controlled by increasing or decreasing the content of Na ₂ O, but if the content of Na ₂ O is 0% by weight, the compatibility with ferrite and ferromagnetic metal materials becomes poor. . Therefore, the content e of Na ₂ O is 0% by weight <e ≦ 12% by weight
And In this case, part of the Na ₂ O may be replaced with K ₂ O. However, when using K ₂ O, it is necessary to increase the content a little, and in order to obtain the same effect as containing 12% by weight of Na ₂ O, the content of K ₂ O is 15% by weight. % Is necessary.

The bonding glass having the above composition has a glass transition point (temperature at which the thermal expansion coefficient changes) of 390 to 420 ° C and a yield point (temperature at which the glass shape does not recover even if cooled) 420 to 450 ° C. , Fusion temperature (working temperature) 550-6
The temperature is 50 ° C., and the thermal expansion coefficient (at 100 to 350 ° C.) is 90 × 10 ^{−7 to} 130 × 10 by changing the addition amount of Na ₂ O.
^-7 [℃ ^-1 ] is set.

The fusing temperature varies depending on the shape and fusing method of the magnetic head, for example, 580 to 600 ° C when flowing a glass rod from a glass groove to form a head gap, and 600 to 630 ° C when uniformly coating glass on a flat surface. Is set.

[Action]

_{PbO, SiO 2, B 2 O} 3, Bi 2 O 3 and increasing or decreasing content of Na ₂ O in the bonding glass consists of Na ₂ O is a great influence on the increase or decrease in the thermal expansion coefficient of the glass. Therefore, the thermal expansion coefficient of bonding can be controlled to an optimum value according to the material of the magnetic head core.

Further, the increase or decrease in the content of Na ₂ O has a great influence on the water resistance of glass, the superiority or inferiority of working temperature, and the deviation from the vitrification range. Therefore, in the present invention, an increase in the increase or decrease at the same time the content of SiO ₂ content of Na ₂ O in order to them stabilize the reliability was reduced with increasing Na ₂ O, the deviation of the working temperature and the vitrification range Restore.

〔Example〕

Hereinafter, the present invention will be described with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

Example PbO, the _{SiO 2, B 2 O 3,} Bi 2 O 3 and Na ₂ O were mixed in proportions shown in Table 1, to prepare a bonding glass for magnetic head.

The thermal expansion coefficient (100 to 350 ° C.) and the glass transition point of each of the obtained bonding glasses (Sample 1 to Sample 5) were measured. The results are shown in Table 2.

From Table 2, it can be seen that the coefficient of thermal expansion of the obtained glass changes depending on the content of Na ₂ O. The working temperature of the obtained glass is almost the same.

Application Example Next, the above-mentioned bonding glass was fused to the magnetic material core, and the optimum thermal expansion coefficient of the bonding glass for the magnetic material for the magnetic head was selected by comparing the magnetic characteristics before and after the fusion.

That is, in the bonding glass of the present invention, the fusion temperature is constant, and the thermal expansion coefficient is 90 × 10 ^{−7 to} 130 × 10.
^{Since the} temperature can be changed up to ⁻⁷ [° C. ⁻¹ ], it is possible to measure the change in the magnetic property of the magnetic material only by the influence of the thermal expansion coefficient of the glass by fusing these glasses. Therefore, the optimum thermal expansion coefficient of the bonding glass used for the magnetic head can be selected by utilizing this.

In this way, a bonding glass having an optimum coefficient of thermal expansion was selected and a magnetic head was manufactured. For example, a single crystal ferrite material having a high coefficient of thermal expansion (135
For fusion bonding of the magnetic core made of × 10 ^-7 ° C ^-1 ) in the working gap portion, the sample 3 (coefficient of thermal expansion 110 × 10 ^-7 ° C ^-1 ) and the sample 4 (thermal expansion) produced in the above-mentioned examples were used. Coefficient 120 × 10
^{When -7} ℃ ^-1 ) was used, a magnetic head without glass crack could be completed.

Similarly, for fusion bonding of 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 cap portion, the sample 3 and the sample prepared in the above-mentioned examples When No. 4 was used, a magnetic head free from glass elution and glass crack was obtained.

Further, when the bonding glass of the present invention is used in a composite magnetic head composed of an oxide magnetic material such as Mn-Zn ferrite and a metal magnetic material such as sendust, the coefficient of thermal expansion of ferrite and sendust is remarkable. The warp caused by the difference was eliminated, and the peeling of the sendust film was also prevented.

〔The invention's effect〕

As is clear from the above description, in the bonding glass of the present invention, since the content of Na ₂ O is increased and the content of SiO ₂ is increased, the thermal expansion coefficient at 100 to 350 ° C. is 90 ×. It can be continuously set up to about 10 ^{-7 to} 130 × 10 ^-7 [℃ ^-1 ], and at the same time the fusion temperature (working temperature) can be maintained at a constant temperature. For example, a magnetic material having a high thermal expansion coefficient can be melted. It is possible to select a bonding glass that minimizes the adhesive stress when wearing. Therefore, it is possible to manufacture a precise head without glass cracks or film peeling.

Further, since the bonding glass of the present invention has sufficient water resistance and hardness to achieve the processing of the magnetic head, it is possible to provide a highly reliable magnetic head also in this respect.

Claims (1)

[Claims] 1. PbO a% by weight, SiO ₂ b% by weight, B ₂ O ₃ c% by weight, Bi ₂ O ₃ d% by weight, Na ₂ O e% by weight, the composition range of which is 49 ≦ a ≦ 69. A bonding glass for a magnetic head, wherein 14≤b≤28 6≤c≤10 5 ≤d≤8 0 <e≤12.