JPH0437626A - Glass and magnetic head - Google Patents

Abstract

PURPOSE:To obtain the accurate dimension and the length of a gap and to improve the production yield by welding and integrating a pair of ferrite cores facing to each other through a gap with using glass containing specified amts. of SiO2, B2O3, Bi2O3, As2O3, etc. CONSTITUTION:The magnetic head consists of a pair of ferrite cores 1, 2 facing each other through a gap 5, and these cores are welded with reinforcing glass 3 into one body. This reinforcing glass contains 25-60wt.% of one or more compds. selected from SiO2, B2O3, and GeO2, 23-60wt.% of Bi2O3, and 0.1-0.5wt.% of As2O3. As for the source material, nitrate is added by 0.5-3.5wt.% (to the compounded source material).

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to glass and a magnetic head for magnetic recording media such as floppy disks, hard disks, and various magnetic tapes.

<Prior art> As shown in FIG. 1, a pair of ferrite cores l,
A magnetic head is known in which the magnetic head 2 is joined through a gap 5 and is welded together with a reinforcing glass 3.

In addition, as shown in FIG. 4, a core block 6 in which a pair of ferrite cores 1.2 are joined through a gap 5
A composite type magnetic head is known in which a slider 8 is sealed and fixed by a seal glass 7.

When manufacturing these magnetic heads, as shown in the figure, reinforced glass 3 is used to bond the cores together, and seal glass 7 is used to bond the core block 6 and slider 8.

These glasses need to have a thermal expansion coefficient that is matched to the member to be joined.

Although it depends on the material of the members to be joined, for example, when joining Mn-Zn ferrite, generally 90 to 110 x 10
It is necessary to have a coefficient of thermal expansion of -0-7 de'.

In such cases, lead glass has conventionally been used to settle and bond the ferrite.

Although lead glass has good wettability with ferrite, 5i
Wetting with the n2 film (gap 51 in FIG. 1) and the glass film (gap 53 in FIG. 1) is poor. For this reason, bubbles are likely to be generated within the reinforced glass 3 during welding. Furthermore, lead glass easily reacts with the ferrite core 1.2, the 5in2 film forming the gap 5, and the glass film. For this reason,
The reinforced glass 3 erodes the ferrite in the APEX portion, or flows into the gap 5 significantly and erodes the ferrite surface forming the gap to obtain accurate gap length, gap depth dimension, and gap line. It is difficult to do so.

Due to these circumstances, the wettability is good (and when welding,
Glass film with gap 5, S i O211! Bismuth glass has been proposed as a low melting point glass that has little reaction with J and ferrite cores.

For example, JP-A-62-230646 and JP-A-63-5
Publication No. 0908 states that rs i O, 33 to 44% by weight, B110i 35 to 50% by weight, alkali metal oxides 5 to 13% by weight, CdO 7 to 11% by weight, and Z
A glass composition for ferrite bonding containing 1 to 3% by weight of rO□. ' has been disclosed.

<Problems to be Solved by the Invention> However, in bismuth glasses including the glass described in the above-mentioned publication, Bi2O3 is easily reduced during glass manufacturing, that is, during glass melting.

For this reason, the reduced Bi forms a metal colloid within the glass, or metal microcrystals of B1 are generated, making it difficult to obtain a stable oxide glass.

Furthermore, due to the reduction of B 120 z and the formation of metal colloids and metal microcrystals, the glass becomes opaque and colored gray, brown, black, etc. as a result.

For this reason, it is difficult to use the above-mentioned bismuth glass as reinforcing glass or sealing glass for magnetic heads.

The purpose of the present invention is to use bismuth glass as a reinforcing glass for magnetic heads without excessively reacting with gap glass or ferrite cores during bonding, and in addition, to prevent bubbles from forming inside the glass during bonding. In addition, Bi and 03 are not reduced during glass manufacturing, and there are no metal colloids, metal microcrystals, etc. formed inside the glass, and the glass is colorless and transparent. An object of the present invention is to provide a magnetic head that has a magnetic head.

<Means for Solving the Problems> Such objects are achieved by the following inventions (1) to (3).

(1) Sin2. 25 to 60% by weight of one or more selected from B, 03 and G e O2, and 23 to 60% of Bi2O3
A glass containing 60% by weight of AS20i and 0.1 to 0.5% by weight of AS20i, characterized in that a nitric acid compound is added as a raw material in an amount of 0.5 to 3.5% by weight of the blended raw materials.

(2) 32-46% by weight of SiO7, 25-58% by weight of Bi2O3, 01-0% of As20m
．． 5% by weight, 5 to 15% by weight of one or more alkali metal oxides selected from Liz OlNa 20, K2O and Rb20, 0 to 10% by weight of one or more selected from MgO, CaO1SrO, BaO and ZnO, Cd
One or more types of 0 selected from O, TI2.0 and PbO
~20% by weight, T i Ox , ZrO□ and Aj2
A glass containing 0 to 5% by weight of one or more selected from 203, wherein a nitrate of one or more alkali metals selected from Li, Na, and Rb is used as a raw material for the alkali metal oxide. 0. A glass characterized in that it is added in an amount of 5 to 3.5% by weight.

(3) A magnetic head in which a pair of ferrite cores are butted against each other through a gap and welded and integrated with reinforcing glass, characterized in that the reinforcing glass is the glass described in (1) or (2) above. magnetic head.

<Function> The glass of the present invention contains B i a O- and AsaOs, and uses a nitric acid compound such as Na NOs as a blending raw material.

Addition of the nitric acid compound prevents the reduction of Bi2O3 and prevents the formation of metal colloids and metal microcrystals. This results in colorless and transparent glass.

In addition, because it has high wettability, which is an inherent characteristic of bismuth glass, it has a high viscosity during welding (although it is difficult for bubbles to form within the glass).

Moreover, it does not excessively react with the SiOz film, gap glass film, or ferrite that forms the gap.

In addition, the magnetic head of the present invention has a bond between the cores (hereinafter referred to as
It is called welding. ) The glass of the present invention is applied as the reinforcing glass used in the above.

Therefore, a magnetic head having reinforced glass without devitrification or coloring of the glass portion and without metal colloids or metal particles in the glass can be realized.

In addition, since bubbles are less likely to form within the reinforcing glass when seven layers are bonded, the production yield is improved, which is advantageous for mass production.

In addition, in a magnetic head using the glass of the present invention as a reinforcing glass, the reinforcing glass is a gap glass film, S
In, since there is no excessive reaction with the film or the ferrite core, there is little penetration of the reinforcing glass into the gap, and a good gap with accurate gap depth, gap length, and gap line can be formed.

It has been known to use a nitric acid compound and A320x in combination for a clarifying effect, and to use a nitric acid compound and ASzOi in combination as a decolorizing agent for F e ''-containing glass.

However, the specific composition of bismuth glass that uses a nitric acid compound and AS203 together as a decolorizing agent is not known.

Moreover, nitrate compound and A S x Ox.

There is no suggestion that Bi2O3 be used in combination to suppress the formation of metal colloids or metal microcrystals during the production of bismuth glass.

<Specific structure of the invention> Hereinafter, the specific configuration of the present invention will be explained in detail.

Glasses particularly suitable for use in magnetic heads of the present invention include SiO2, B20. and Ge
Contains one or more selected from O2, especially SiO□.

1 selected from 5iOz, BzOs and G e Ox
The content of seeds and above shall be 25 to 60% by weight.

If it is less than the above range, vitrification is difficult and devitrification is likely to occur.

If the above range is exceeded, 90≦α≦120×10-0-7d
e' and thermal characteristics of 700≦Tw≦900°C cannot be obtained.

Note that a is a coefficient of thermal expansion.

Further, Tw is the temperature at which the viscosity of the glass becomes 10'poise, and is usually called the working temperature.

In this case, the content of SiO2 is preferably 32 to 46% by weight.

If it is less than the above range, the characteristics of bismuth glass mentioned above cannot be obtained, and if it exceeds the above range, the necessary thermal properties (90
≦a≦120X10deg-', 700≦Tw≦900
℃) becomes difficult to obtain.

The glass of the present invention contains B i 203 and A S
203 is contained.

The content of Bi25s is 23 to 60% by weight, preferably 25 to 58% by weight.

Below the above range, the necessary thermal properties (90≦a≦120X
10-'de'g-', 700≦Tw≦900℃)
It becomes difficult to obtain.

If it exceeds the above range, vitrification becomes difficult and the characteristics of bismuth glass described above cannot be obtained.

The content of As x 03 is 0.1 to 0.5%.

If it is less than the above range, no effect as an oxidizing agent can be obtained, and if it exceeds the above range, a colloid of B i -As alloy is likely to be produced.

Further, the glass of the present invention preferably contains 5 to 15% by weight of one or more alkali metal oxides selected from Li2O, Na2O, K2O and RbaO in order to control thermal properties.

Below the above range, a<90 x l O-' deg-
'Or, Tw>900'C.

Beyond the above range, a>120X10 deg-' or Tw<700°C.

In this case, the content of Li2O is 0 to 3% by weight, Naa
The content of O is 0.1 to 10% by weight, the content of K2O is 01 to 10% by weight, and the content of Rh and O is 0 to 10% by weight.
It is preferable that

Further, it contains 0 to 10% by weight of one or more selected from MgO, Cab, 5rO1BaO, and ZnO.

Beyond the above range, the tendency for devitrification increases.

It contains 0 to 20% by weight of one or more selected from Mf, -1CdO, Tf220 and PbO.

If it exceeds the above range, the above-mentioned characteristics of bismuth glass will be lost.

Also, T 102 , Z r O2 and A (22
Contains 0 to 5% by weight of one or more selected from 03.

If it exceeds the above range, the tendency for devitrification increases.

FL of the glass of the present invention may be carried out, for example, as follows.

First, raw materials are blended into a predetermined composition according to the desired glass composition, and after being sufficiently melted in a hot pot, it is cooled.

In this case, the feature of the present invention is that the nitric acid compound is contained as a raw material in an amount of 0.5 to 35% by weight, preferably 1.5 to 35% by weight of the blended raw material.
0% by weight is used.

In bismuth glass, reduction of Bi2O3 is suppressed by using a nitric acid compound and AS203 together.

Therefore, the formation of metal colloids and metal microcrystals can be prevented, and colorless and transparent bismuth glass can be obtained.

However, if it is less than the above range, the effect of adding the nitric acid compound cannot be obtained.If it exceeds the above range, foaming tends to occur and excessive gas tends to be produced in the glass.

There are no particular restrictions on the nitric acid compound used. for example,
Examples include nitrates of alkali metals, alkaline earth metals, etc., and one or more of these nitric acid compounds may be used.

Among these, nitrates of one or more alkali metals selected from Li, Na, and Rb are particularly preferred.

Also, L i 20. Na2O, Ni20 and Rb2O
In order to produce the glass of the present invention containing one or more selected from Li, Na, and Rb, one or more alkali metal nitrates are mixed as raw materials.
．． 5-3.5% by weight, preferably 1.5-3.0% by weight
use.

If the amount is less than the above range, the effect of adding an alkali metal nitrate cannot be obtained.

If it exceeds the above range, foaming tends to occur and excessive gas tends to form in the glass.

In addition, when using two or more types of alkali metal oxides together, the number of alkali metal nitrates added may be one type or two or more types.

Here, the added nitric acid compound, for example, N a N O
3 and KNO, are metal oxides such as N after melting and cooling.
Since the glass composition varies from 20 to 20, it is impossible to directly determine the present invention from the obtained glass composition.

However, without the presence of nitrate compounds (nitrates), AS2
There is no effect of the presence of 0g. That is, the effect of preventing Bi reduction and decoloring in bismuth glass is not exhibited.

For this reason, bismuth glass that is not based on the present invention, that is, bismuth glass that does not use A S 20 z and a nitric acid compound in combination, is not colorless and transparent.

Therefore, it is possible to distinguish between the glass of the present invention and the glass produced without using As2's and a nitrate compound based on the degree of coloration and transparency of the glass.

The working temperature Tw of the glass of the present invention obtained in this way
is about 700-900℃, thermal expansion coefficient is 100-3
It is about 90 to 120 x 10-'deg-' at 00°C.

When the glass of the present invention is used in a magnetic head, thermal properties such as thermal expansion coefficient, working temperature Tw, and viscosity may be appropriately selected depending on the respective use.

Next, an example in which the glass of the present invention is applied to reinforcing glass for a magnetic head will be described together with the magnetic head of the present invention.

FIG. 1 shows a preferred embodiment of the magnetic head of the present invention.

The magnetic head shown in FIG. 1 has a first core 1 and a second core 2 facing each other with a gap 5 interposed therebetween. It has been stopped.

Then, winding is applied to such a core block to form a magnetic head.

The magnetic head shown in FIG. 2 has a structure in which reinforcing glass 3 is exposed on both sides of a gap 5 on the front surface of the magnetic head.

The magnetic head shown in FIG. 3 is a monolithic floating type magnetic L-rad, and the configuration of the gear part is the same as that of the magnetic head shown in FIG. 1.

In the magnetic glasses shown in FIGS. 1 to 3, the glass reinforcement of the present invention is used as the reinforcing glass 3.

In the configuration shown in FIGS. 1 and 3, the first core 1 and the second core 2 are opposed to each other with a gap 5 interposed therebetween, and a reinforcing glass raw material such as glass fiber is placed on the winding window or the back side of the core block. Then, heat treatment is performed to form the reinforced glass 3.

Further, in the configuration shown in FIG. 2, reinforced glass is formed by placing glass raw materials on both sides of the gap 5 and on the back side of the core block and heat-treating them at the same time. Next, the front surface is smoothed by polishing or the like.

In the configuration shown in FIG. 2, the reinforcing glass 3 on the back side of the core block is made of high-strength glass with high SiO□, and the reinforcing glass 3 on both sides of the gap 5 on the front side is made of the glass of the present invention. may be configured.

In this case, since high-strength high-Sin glass generally has a higher working temperature Tw than the glass of the present invention, the back side of the core block is welded with the high-strength glass, and the front side is further welded with the glass of the present invention. .

With such a configuration, a magnetic head with even higher strength can be obtained in addition to realizing the effects of the present invention.

FIG. 4 shows an example of a composite type magnetic head which is a preferred embodiment of the magnetic head of the present invention.

The core block 6 is configured similarly to the core block shown in FIG. 1, for example.

Then, this core block 6 is inserted into the core block insertion notch of the slider 8, and both are bonded and sealed (2-blow bonding) with a seal glass 7 for sealing the magnetic head, and the winding 9 is wound. Turn it to create a magnetic head.

In such a composite type magnetic head,
The glass of the present invention is used for the reinforced glass 3.

In addition, during the above-mentioned sealing, the arrival temperature is set to the working temperature Tw.
nearby, and use the usual method.

The glass of the present invention used for the reinforced glass 3 is as described above.

In this case, the welding temperature is around the working temperature (B degree TW), and is usually about 700 to 900°C.

In the present invention, the first core 1 and the second core 2 are made of ferrite.

The ferrite used is not particularly limited, but it is preferable to select it from Mn-Zn ferrite or Ni-Zn ferrite depending on the purpose.

In addition, 10 of the first core and second core 2 made of ferrite
The coefficient of thermal expansion at 0-300℃ is.

90X l O-" ~ 150X 10-'deg-'
That's about it.

Gap 5 is made of a non-magnetic material.

In particular, it is preferable to use glass for the gap 5 in order to increase adhesive strength. In this case, gap 5 has
For example, the same or similar glass as the amorphous glass base film of ('i gc), such as lead-silica glass or silica-alkali glass, may be used.

Further, the gap 5 may be formed only of glass, but in order to increase the gap formation speed, it is preferably formed of two layers, a gap 51 and a gap 53, as shown.

In this case, the gap 51 is made of silicon oxide, especially 5in2
It is preferable to use lead-silica glass, silica-alkali glass, or the like for the gap 53.

Although there are no restrictions on the method for forming the gap 5, it is particularly preferable to use a sputtering method.

The slider 8 is made of non-magnetic ceramics such as potassium titanate, calcium titanate, strontium titanate, etc.
Crystallized glass or the like is used. In addition, 100 to 300"C of such non-magnetic ceramics and crystallized glass
Thermal expansion coefficient (190X 10-7 to I 20X 1
It is about 0-'deg-'.

The present invention relates to a floppy head that performs override recording such as a tunnel erase type such as a so-called laminate type or bulk type or a read/write type without an erase head, and a floating type computer head such as the monolithic type or composite type mentioned above. , and is applied to various magnetic heads such as VTR heads using rotating cylinders.

<Example> Hereinafter, the present invention will be explained in further detail by giving specific examples of the present invention.

Example 1 Glass A of the present invention was manufactured by sufficiently melting the following blended raw materials in the atmosphere and then cooling them.

5i02: 37.3% by weight B1□O,: 39.7% by weight AS20. s: 0.2% by weight NaNO3: 2.6% by weight Na2COs: 5.1% by weight 2CO3: 8.1% by weight CdO 0% by weight In addition, in the same manner, comparisons were made with glasses B and C of the present invention. Glasses D and E were manufactured.

In addition, in the case of bismuth glass D for comparison, no nitric acid compound was used as a raw material.

Composition of glasses A to F, coefficient of thermal expansion αtoo-3° at 100 to 300°C. and the working temperature Tw are as shown in Table 1.

In addition, the obtained glasses A to E were observed with an intraocular lens and an optical microscope, and the glasses were evaluated regarding the formation of metal colloids and metal microcrystals and the degree of coloration of the glasses.

Evaluation criteria O: Colorless and transparent, no metal colloids or metal microcrystals formed ×: Colored and opaque, metal colloids or metal microcrystals formed (difficult for practical use due to appearance) The results are shown in Table 1. .

Next, the first core 1 and the second core 2 are integrally joined through the gear/y-brake 5 to form monolithic type magnetic head samples Nos. 1 to 3 shown in FIG. 3, and a comparison sample. N014 and 5 were manufactured.

The reinforcing glass used for welding the core of each sample is as shown in Table 2, and the welding temperature is also listed in the table.

In addition, the glass D for comparison was difficult to put into practical use (poor appearance) as described above. However, it is impossible to make a magnetic head by welding the core.

Mn-Zn ferrite was used as the material for the core 1.2.

The thermal expansion coefficient of each core at 100-300℃ is 125
~135×10-'deg-'.

The gap 51 was 5 in 2 and formed by sputtering, and the film thickness was 0.4 p.

In the gap 53, 68, 2S 102 4, 5CaO2
, 4820x -6,1Na 20-15. 2K
A glass having a composition of 20-3.2PbO0,4As-03 (wt%) and a working temperature Tw of 964°C was used.

Note that the gap 53 was formed by sputtering, and its film thickness was set to 0.2-.

The following evaluation was performed for each sample.

l) Reinforced glass of magnetic head (bubble generation after welding)
Evaluation After welding, the reinforced glass is observed with a metallurgical microscope (X100) to confirm the presence or absence of foaming.

2) Evaluation of the gap part of the magnetic head After welding, the gap part of the magnetic head is observed with an electron microscope to check the effects of the reaction between the ferrite core and the welded glass and the reaction between the gap glass and the welded glass.

Evaluation criteria ○: No change ×: The reinforcing glass flows into the gap, and at the same time, due to erosion of the ferrite core, changes in the gap length, gap depth dimensions, and disturbance of the gap line occur.

Separately from the magnetic head described above, after welding was performed at a viscosity of 10'poise, the gap part of the magnetic head was observed using a metallurgical microscope, and the amount of penetration of the reinforcing glass into the gap was determined. .

In this case, the amount of penetration of the reinforcing glass was determined as the depth from the original APEX to the point where a normal gap exists.

It should be noted that there is no problem at all as long as the amount of penetration of the reinforcing glass is about 5 or less.

The results are shown in Table 2.

O 1 (Invention) 2 (Invention) 3 (Invention) 4 (Comparison) 5 (Comparison) Amount of intrusion in state of front glass ('C) ABO3 small ○ ]B2S3
Low ○ C810 Low ○ B8S0 Low ○ 1E73
0 Many X 10 Table 1
From the results shown in Table 2, the effects of the present invention are clear.

In addition, in head samples Nos. 1 to 3 of the present invention,
Since a gap of a predetermined size was formed, high output characteristics were obtained. In addition, chemical durability was also good.

In addition, instead of or in addition to the alkali metal nitrate, a glass and a magnetic head were manufactured in the same manner as described above by adding an alkaline earth metal nitrate as a raw material.

When the same evaluations as above were carried out, almost the same results were obtained.

[Example 2] In the same manner as in Example 1, as shown in FIG.
The core 1 and the second core 2 are integrally bonded to each other by a reinforced glass 3 via a gap 5 to form a core block, and a fourth core block is formed.
The composite type magnetic head shown in the figure was manufactured.

Then, when the same evaluation as in Example 1 was performed, the same results were obtained.

The effects of the present invention are clear from the above results.

<Effects of the Invention> Since the glass of the present invention has high wettability, even if the viscosity at the time of welding is increased, air bubbles are not generated within the glass.

In addition, even if welding is performed at a high temperature of 800° C. or higher, there will be no excessive reaction with other members such as the glass film, SiO2 film, or ferrite in the gap.

Moreover, there are no metal colloids or metal microcrystals in the glass,
It is colorless and transparent and has high chemical durability.

Furthermore, the magnetic head of the present invention using such glass as the reinforcing glass has accurate gap depth dimensions, gap lengths, and undisturbed gap lines.

Therefore, high output characteristics can be obtained.

In addition, since no air bubbles are generated within the glass during welding, production yields are improved, and there is no need to strictly control the deposition conditions as is the case when using conventional high lead glass. Mass productivity is greatly improved.

It has the above characteristics and is free from devitrification and discoloration.
A magnetic head with reinforced glass free of metal colloids and metal particles is realized.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an example of the magnetic head of the present invention. FIG. 2 is a perspective view showing an example of the magnetic head of the present invention. FIG. 3 is a perspective view showing an example of the monolithic type magnetic head of the present invention. FIG. 4 is a perspective view showing an example of a composite type magnetic head of the present invention. Description of stone bones 1...First core 2...Second core 3...Reinforced glass 5.51.53...Gap 6...Core block 7...Seal glass for magnetic head arrival 8 ...Slider 9...Winding

Claims (3)

[Claims] (1) A glass containing 25 to 60% by weight of one or more selected from SiO_2, B_2O_3 and GeO_2, 23 to 60% by weight of Bi_2O_3, and 0.1 to 0.5% by weight of As_2O_3, as raw materials, A glass characterized in that a nitric acid compound is added in an amount of 0.5 to 3.5% by weight of the blended raw materials. (2) 32-46% by weight of SiO_2, 25-58% by weight of Bi_2O_3, 0.1-0.5% by weight of As_2O_3, Li_2O, Na_2O, K_
5 to 15% by weight of one or more alkali metal oxides selected from 2O and Rb_2O, 0 to 10% by weight of one or more selected from MgO, CaO, SrO, BaO and ZnO, selected from CdO, Tl_2O and PbO. TiO_2, ZrO_2 and Al
A glass containing 0 to 5% by weight of one or more selected from _2O_3, which contains a nitrate of one or more alkali metals selected from Li, Na, K, and Rb as a raw material for the alkali metal oxide. A glass characterized in that 0.5 to 3.5% by weight of is added. (3) A magnetic head in which a pair of ferrite cores are abutted against each other through a gap and welded and integrated with reinforcing glass, wherein the reinforcing glass is the glass according to claim 1 or 2. head.