JPH0826771A - Glass for bonding magnetic head - Google Patents

Abstract

PURPOSE:To obtain glass having a coefft. of thermal expansion fit for ferrite and satisfactory cleaning liq. and water resistances and suitable for use as glass for the secondary bonding of a magnetic head. CONSTITUTION:This glass consists of, by weight, 65-77% PbO, 13.5-20% SiO2, 2-8% B2O3, 0.1-3% Al2O3, 0-4% ZnO, 0-10% Bi2O3, 0-10% TeO and 0.05-3% Co3O4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head glass, and more particularly to a magnetic head glass used as a secondary bonding glass.

[0002]

2. Description of the Related Art Adhesive glass has been conventionally used as a joining or filling member in the manufacture of magnetic heads. As a magnetic head using such an adhesive glass, for example, there is a floppy disk (FDD) head as shown in FIG. 1 and a hard disk (HDD) head as shown in FIG.

When manufacturing a head for an FDD, first of all, the ferrite magnetic core halves 11a, 11b, 11'a,
11'b are bonded and fixed to each other with the primary bonding glasses 13 and 13 'through the gap spacers 12 and 12' to produce the R (read) / W (write) core 11 and the erase core 11 ', The head 10 is formed by bonding and fixing these with the glass 14 for secondary bonding.

In the case of an HDD head, magnetic core halves made of a magnetic material such as ferrite are bonded to each other with a primary bonding glass via a gap spacer to prepare a magnetic core 21, which is made of a non-magnetic ceramic. The head 20 is formed by holding the slider 22 made of a magnetic material or a magnetic ferrite material in the cut portion, filling the voids with the secondary bonding glass 23, and bonding and fixing the magnetic core.

By the way, the secondary bonding glass used for manufacturing the magnetic head has a coefficient of thermal expansion adapted to ferrite, which is a material of the magnetic head, and the primary bonding glass is softened and fluidized by heat treatment to cause a gap length. A glass having a low melting point that can be heat-treated at a temperature equal to or lower than the yielding point of the primary bonding glass is used so that the temperature does not increase and the effective track width does not decrease.

[0006]

However, low-melting-point glass having a high coefficient of thermal expansion that is compatible with ferrite generally has low cleaning liquid resistance and water resistance, and when such glass is used as a glass for secondary bonding. In addition, there are problems that the glass is deteriorated in a cleaning process after the head is assembled, or foreign matter is deposited on the glass surface by reacting with moisture in the atmosphere to damage the disk surface.

It is an object of the present invention to provide a magnetic head bonding glass which has a coefficient of thermal expansion suitable for ferrite and is excellent in cleaning liquid resistance and water resistance and which is suitable as a glass for secondary bonding of a magnetic head. Is.

[0008]

As a result of various researches conducted by the present inventors in order to achieve the above object, PbO-Si is obtained.
By incorporating the _{O 2 -B 2 O 3 -Al 2} O 3 specific amount to the low-melting glass systems Co ₃ O _4, resistance to washing liquid and water resistance is good, yet adhesive having an appropriate coefficient of expansion It has been found that a glass can be obtained and is proposed as the present invention.

That is, the glass for adhering a magnetic head of the present invention contains PbO 65 to 77% and SiO ₂ 1 in weight percentage.
_{3.5~20%, B 2 O 3 2~8} %, Al 2 O 3 0.1
~ 3%, ZnO 0-4%, Bi ₂ O ₃ 0-10%, T
eO ₂ 0-10%, Co ₃ O ₄ 0.05-3%.

[0010]

The low melting point glass of the present invention has a coefficient of thermal expansion of 30 to 300 ° C. that of ferrite (100 to 120 ×).
10 ^-7 / ℃) is 90~110 × 10 ^-7 / ℃ to meet,
Further, since the softening point is 450 to 490 ° C., it is lower than the yield point (usually 550 to 580 ° C.) of the glass for primary bonding 55.
It is possible to perform heat treatment at 0 ° C. or lower. Moreover, Co ₃
Since it contains O ₄ , it has excellent cleaning liquid resistance and water resistance.

Next, the reasons why the composition of the low melting point glass of the present invention is limited as described above will be shown below.

PbO is a component that lowers the melting point of glass, and its content is 65 to 77%. 65% PbO
If it is less, the softening point will be higher, and if it is more than 77%, the water resistance will be poor.

SiO ₂ is a component that expands the vitrification range, and its content is 13.5 to 20%. If the SiO ₂ content is less than 13.5%, the water resistance will be poor, and if it exceeds 20%, the softening point will be high, making it difficult to lower the melting point.

B ₂ O ₃ is a component that stabilizes the glass, and its content is 2 to 8%. When B ₂ O ₃ is less than 2%, the glass becomes unstable, and when it is more than 8%, the water resistance becomes poor.

Al ₂ O ₃ is a component that enhances the cleaning liquid resistance and water resistance of glass, and its content is 0.1 to 3%. If Al ₂ O ₃ is less than 0.1%, the above effect cannot be obtained, and if it exceeds 3%, the softening point of the glass becomes high and heat treatment cannot be performed at 550 ° C. or lower.

ZnO is a component that lowers the melting point of glass without increasing its coefficient of thermal expansion, and its content is 0 to 4%. If ZnO is more than 4%, the glass tends to devitrify.

Bi ₂ O ₃ has a function of lowering the softening point of glass, and its content is 0 to 10%. If the content of Bi ₂ O ₃ is more than 10%, the glass becomes colored and becomes opaque, making it difficult to measure the gap depth.

TeO ₂ has the effect of improving the water resistance of lead-based glass, and its content is 0-10%. TeO ₂
Is more than 10%, the softening point becomes high.

Co ₃ O ₄ is a component that enhances the cleaning liquid resistance and water resistance of glass, and its content is 0.05 to 3%. If the content of Co ₃ O ₄ is less than 0.05%, the effect is not exerted, and if it exceeds 3%, the glass tends to devitrify and the glass becomes unstable.

[0020]

EXAMPLES The glass for magnetic head adhesion 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 Comparative Examples (Sample Nos. 5 and 6).

[0022]

[Table 1]

No. in the table Each sample of 1 to 6 was prepared as follows.

First, a raw material batch prepared so as to have the composition shown in the table in percentage by weight was placed in a platinum crucible, melted at 1100 ° C. for 1 hour, molded into a predetermined shape to prepare a sample, and then a coefficient of thermal expansion and softening. The spot, heat treatment temperature, cleaning liquid resistance and water resistance were measured.

As is apparent from the table, No.
Each sample of 1 to 4 has a thermal expansion coefficient of 90 to 100 × 10 ⁻⁷ /
℃, softening point 460-490 ℃, heat treatment temperature 510
The value was 540 ° C., and the washing liquid resistance and water resistance were good. On the other hand, No. The thermal expansion coefficient of each of samples 5 and 6 is 100 × 10 ⁻⁷ / ° C. and 90 × 1
The temperature was 0 ^-7 / ° C, the softening points were 470 ° C and 465 ° C, and the heat treatment temperatures were 520 ° C, which were the same values as those of the examples, but both the cleaning liquid resistance and the water resistance were poor.

These facts show that the present invention conforms to the coefficient of thermal expansion of ferrite, and has good cleaning liquid resistance and water resistance.

The thermal expansion coefficient of each glass is 5φ × 20.
It measured with the average linear thermal expansion coefficient measuring device using the sample shape | molded by the rod shape of mm. The softening point was measured using a differential thermal analyzer by crushing each glass, passing through a sieve having an opening of 105 μm to prepare a powdery sample. The heat treatment temperature is a temperature at which the fluidity necessary for fixing the head core is obtained,
That is, the temperature when the viscosity of the glass shows 10 ⁴ poise was measured by a high temperature viscometer. The cleaning liquid resistance was evaluated as follows. First, each glass was formed into a strip shape of 10 × 25 × 3 mm, and the surface was further polished to obtain a sample. Then, half of the sample was coated and left for 2 hours in a 50 ° C. solution in which a commercially available alkaline cleaning solution was diluted to 2% with distilled water, and then the level difference generated by the stylus type surface profile measuring instrument was measured. Is 0.5 μm or less, it is good, and if it exceeds 0.5 μm, it is bad. For water resistance, prepare a half-coated sample in the same manner as the sample used for the evaluation of cleaning liquid resistance, and then boil this in pure water at 95 ° C or higher for 2 hours, and then use a stylus type profilometer. The generated step was measured, and when the step was 0.3 μm or less, it was judged as good, and when it exceeded 0.3 μm, it was judged as bad.

[0028]

As described above, the glass for magnetic head adhesion of the present invention has a coefficient of thermal expansion suitable for ferrite, and can be heat-treated at a temperature not higher than the yield point of the glass for primary adhesion. Since it has good cleaning liquid resistance and water resistance, it is particularly suitable as a secondary bonding glass used in the manufacturing process of FDD heads, HDD heads and the like.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an FDD head.

FIG. 2 is an explanatory diagram showing an HDD head.

[Explanation of symbols]

 10 FDD Head 11 R / W Core 11 'Erase Core 14 Secondary Adhesion Glass 20 HDD Head 21 Magnetic Core 22 Slider 23 Secondary Adhesion Glass

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 5/60 V 7811-5D

Claims (1)

[Claims] 1. PbO 65-77%, S by weight percentage
_{iO 2 13.5~20%, B 2 O} 3 2~8%, Al 2 O
₃ 0.1-3%, ZnO 0-4%, Bi ₂ O ₃ 0-1
0%, TeO ₂ 0-10%, Co ₃ O ₄ 0.05-3%
A glass for bonding a magnetic head, which is made of