JPH0891868A - Glass for sticking ferrite - Google Patents

Abstract

PURPOSE: To obtain glass for sticking ferrite enabling to perform thermal treatment at a temp. equal to conventional glass and being suitable as a primary adhesive glass with a magnetic head having a transition point higher than conventional glass. CONSTITUTION: This glass consists of (by wt.) 20-45% SiO2 , 8-20% B2 O3 , 15-26% BaO, 0-2.5% MgO, 5-12% Na2 O, 0-5% Li2 O, 3-14% TiO2 , 6-15% ZnO, 2-5% Fe2 O3 and 0.1-1% MnO2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrite bonding glass used for assembling a magnetic head incorporated in a floppy disk drive, a hard disk drive or the like.

[0002]

2. Description of the Related Art Conventionally, a magnetic head is often manufactured by using two or more kinds of bonding glass. For example, in a magnetic head used for a floppy disk drive, the magnetic core halves made of an oxide magnetic material such as ferrite are bonded together by a primary adhesive glass to form a recording / reproducing head section and an erasing head section, and then a recording / reproducing head section is formed.
The reproducing head portion and the erasing head portion are bonded with a secondary adhesive glass. Further, it is manufactured by adhering and fixing this to a slider made of a non-magnetic ceramic material with a tertiary adhesive glass or an organic adhesive.

Therefore, in the manufacturing process of the magnetic head, heat treatment of 2 to 3 times is performed. However, when heat treatment of the secondary or tertiary adhesive glass, the adhesive glass of lower order is loosened or deformed. It is desirable that the heat treatment is performed at a temperature not higher than the transition point (Tg) of the low-order adhesive glass so as to prevent the occurrence of heat. Therefore, low-viscosity lead glass that can be heat-treated at low temperature is widely used for high-order adhesive glass, and high-viscosity borosilicate glass that has a relatively high heat treatment temperature is used for low-order adhesive glass.

[0004]

However, since many lead-based glasses have problems in hardness and cleaning liquid resistance, in recent years, it has been advisable to use a glass containing as little lead as possible as a high-order adhesive glass. Is proposed.
However, if the lead content is reduced, the viscosity becomes higher, so the heat treatment temperature must be raised, and therefore, the transition point of the glass of lower order must be set higher. As a result, the heat treatment temperature of the most viscous primary adhesive glass becomes too high, which deteriorates the magnetic properties of the ferrite and causes the glass to erode the ferrite.

Therefore, by making the viscosity characteristics of each adhesive glass, especially the primary adhesive glass short (a property in which the viscosity sharply decreases when the transition point is exceeded), the secondary adhesive glass can be treated without increasing the heat treatment temperature of the secondary adhesive glass. Such a glass is being developed because the heat treatment temperature of the tertiary adhesive glass can be set high.

An object of the present invention is to provide a glass for ferrite bonding which can be heat-treated at a temperature equivalent to that of conventional glass and is suitable as an adhesive glass for a magnetic head having a higher transition point than conventional glass.

[0007]

The glass for ferrite bonding according to the present invention comprises SiO _{2 of 20 to} 45% by weight and B _{2 of} B ₂ by weight percentage.
O ₃ 8-20% BaO 15-26%, MgO 0-
_{2.5%, Na 2 O5~12%,} Li 2 O 0~5%,
TiO ₂ 3-14%, ZnO 6-15%, Fe ₂ O ₃
2 to 5% and MnO ₂ 0.1 to 1%.

[0008]

The glass for ferrite bonding of the present invention has a coefficient of thermal expansion of ferrite (10
0-120 × 10 ^-7 / ° C) compatible with 100-110 ×
It is 10 ^-7 / ° C. Further, since it contains TiO ₂ in a specific amount, it can be heat treated at 740 to 750 ° C., which is equivalent to that of conventional primary adhesive glass, and has a transition point of 15 to 25 ° C. as compared with conventional glass.
It is a short glass with a high price.

Next, the reason for limiting the composition range of the glass for bonding ferrite of the present invention as described above will be described.

SiO ₂ is a component that expands the vitrification range and improves the hardness and cleaning liquid resistance of glass, and its content is 20 to 45%, preferably 29 to 42.
%. If the SiO ₂ content is more than 45%, the viscosity of the glass increases and the heat treatment temperature becomes too high, and if it is less than 20%, the cleaning liquid resistance decreases.

B ₂ O ₃ is a component that stabilizes glass, and its content is 8 to 20%, preferably 8 to 15%. If the content of B ₂ O ₃ is more than 20%, the heat treatment temperature becomes high, and the interfacial reaction with ferrite easily occurs.
If it is less than%, the glass becomes unstable.

BaO is a component for adjusting the coefficient of thermal expansion and a component for lowering the softening point and the heat treatment temperature, and its content is 15-26%, preferably 17-.
26%. If BaO is more than 26%, the glass tends to devitrify, and if it is less than 15%, an appropriate expansion coefficient cannot be obtained or the heat treatment temperature becomes too high.

MgO can be added up to 2.5% in order to improve compatibility with ferrite.

Na ₂ O is a component that lowers the softening point and the heat treatment temperature, and its content is 5 to 12%, preferably 8 to 12%. If the content of Na ₂ O is more than 12%, the coefficient of thermal expansion becomes too high and the resistance to cleaning liquid decreases, and
%, The heat treatment temperature becomes too high.

Li ₂ O is also a component added to lower the softening point and the heat treatment temperature, and the content thereof is 0-5.
%, Preferably 0-2%. If the content of Li ₂ O is more than 5%, the coefficient of thermal expansion becomes too high, and the resistance to cleaning liquid decreases.

TiO ₂ is a component that lowers the viscosity of the glass and makes the glass short-circuited, and its content is 3 to 14%,
It is preferably 4 to 14%. If TiO ₂ is more than 14%, the glass tends to devitrify, and if it is less than 3%, the effect is not obtained.

ZnO has the effect of improving the wettability with ferrite and reducing the viscosity in the high temperature range, and the content thereof is 6 to 15%, preferably 8 to 15%. ZnO
If it is more than 15%, the glass tends to devitrify during heat treatment, and if it is less than 6%, its effect is not obtained.

Fe ₂ O ₃ is a component that improves the wettability with ferrite and prevents erosion, and its content is 2-5.
%. If the Fe ₂ O ₃ content is more than 5%, the glass will be colored, making it difficult to measure the gap depth. If it is less than 2%, the effect will not be obtained.

MnO ₂ is a component that improves the wettability with ferrite and prevents erosion, and its content is 0.1-0.1%.
It is 1%, preferably 0.3 to 0.6%. If MnO ₂ is more than 1%, the glass is colored and it becomes difficult to measure the gap depth, and if it is less than 0.1%, the effect is not obtained.

[0020]

EXAMPLES The glass for bonding ferrite of the present invention will be described below based on examples.

Table 1 shows examples of the present invention (Sample Nos. 1 to 1).
4) and a conventional glass (Sample No. 5) which is a comparative example.

[0022]

[Table 1]

Each sample was prepared as follows. First, glass raw materials were prepared so that the weight percentages were as shown in the table, put in a platinum crucible, melted at 1,300 ° C. for 1.5 hours, and then molded into a predetermined shape to prepare a sample. The thermal expansion coefficient, the transition point, the heat treatment temperature, and the cleaning liquid resistance of the sample thus obtained were evaluated. The results are shown in Table 1.

As is clear from Table 1, each sample of the examples has a thermal expansion coefficient of 100 to 110 × 10 ⁻⁷ / ° C., a transition point of 510 to 520 ° C., a softening point of 640 to 655 ° C., and a heat treatment temperature. Was 740 to 750 ° C. In addition, the cleaning liquid resistance of each sample was good.

On the other hand, No. Sample No. 5 has a coefficient of thermal expansion of 105 × 10 ⁻⁷ / ° C. and a softening point of 650.
℃, the heat treatment temperature is 750 ℃ shows the same value as the example,
The cleaning liquid resistance was also good. However, the transition point was 495 ° C., which was 15 to 25 ° C. lower than that of each sample of the example.

These facts indicate that the bonding glass of the present invention has T
Since it contains iO ₂ , it can be heat-treated at a temperature equivalent to that of the conventional glass, and it is a short glass having a higher transition point than the conventional glass.

The thermal expansion coefficient of each glass is 5φ × 20.
It measured by the average linear thermal expansion measuring device using the sample shape | molded by the rod shape of mm. The transition point is crushing each glass,
A powdery sample obtained by passing through a sieve having an opening of 105 μm was used for measurement with a differential thermal analyzer. The heat treatment temperature was measured by a high temperature viscometer at a temperature at which the fluidity required during the heat treatment was obtained, that is, the temperature at which the glass had a viscosity of 10 ⁴ poise. The cleaning liquid resistance was measured as follows. First, each glass was formed into a strip of 10 × 25 × 3 mm, and the surface was polished to prepare a sample. Then, half of the sample was coated and immersed in a commercially available alkaline cleaning solution diluted with distilled water to a concentration of 2% at 50 ° C for 2 hours, and then the level difference generated by a stylus type profilometer was measured. Of 0.2 μm or less was considered good, and those exceeding 0.2 μm were considered bad.

[0028]

As described above, the glass for bonding ferrite of the present invention satisfies various characteristics required for glass used for bonding ferrite, and is a magnetic head used for floppy disk drives, hard disk drives and the like. It is suitable as an adhesive glass.

Especially when used as a primary adhesive glass,
Because it can be heat treated at the same temperature as conventional glass and has a high transition point, it is possible to use glass with a higher heat treatment temperature than conventional glass for high-order bonding glass such as secondary adhesive glass and tertiary adhesive glass. The present invention makes it possible to increase the hardness of high-order glass and improve the cleaning liquid resistance without causing the problems of deterioration of the magnetic properties of ferrite and erosion by glass.

Claims (1)

[Claims] 1. SiO ₂ 20-45% by weight percentage, B
₂ O ₃ 8-20%, BaO 15-26%, MgO 0
_{~2.5%, Na 2 O 5~12%} , Li 2 O 0~5
%, TiO _{2 3 to} 14%, ZnO 6 to 15%, Fe ₂
A glass for ferrite bonding, characterized by comprising _{2 to} 5% of O _{3 and} 0.1 to 1% of MnO ₂ .