JPS60186437A - Glass composition for ferrite adhesion - Google Patents

Abstract

PURPOSE:The titled composition that contains silica, the major component, and other metal oxides in a specific proportion and enables the formation of gaps with high precision without etching in the production of ferrite magnet heads. CONSTITUTION:The objective glass composition for ferrite bonding is composed of (A) 32-46wt% of SiO2, (B) 12-22wt% of PbO, (C) 10-14wt% of Na2O, (D) 9-13wt% of B2O3, (E) 4-8wt% of Fe2O3, (F) 0.5-3wt% of V2O3, (G) 1-5wt% of Al2O3, (H) 1-4wt% of at least one from ZnO, CaO, MgO and CdO, (I) less than 4wt% of MnO and (J) less than 0.4wt% of K2O.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass composition (used for bonding ferrite), including, but not limited to, a glass composition suitable for bonding ferrite, suitable for forming a gap in a magnetic head made of ferrite. This invention relates to glass compositions.

Hereinafter, the case of gap formation in a ferrite magnetic head, to which the present invention is most effectively applied, will be explained as an example.

The most common magnetic heads that record and reproduce signals on magnetic recording media such as magnetic tapes and magnetic disks have a structure in which a gap exists facing the magnetic recording medium, and magnetic flux leaks from the gap. is configured to magnetize a magnetic recording medium to record information, and to reproduce information recorded on the magnetic recording medium by detecting that residual magnetic flux of the magnetic recording medium enters from the gap portion. There is.

A magnetic head like Otsu has a cross section U as shown in Figure 1.
Ferrite core shaped like a letter (U-bar type ferrite core)
1 and a ferrite core (I-bar type ferrite core) 2 having a rectangular cross section are bonded together at their joints using glass adhesives 3a and 3b, and then are assembled by slicing them thinly.

In this case, the joint that will later face the magnetic recording medium (here, the joint where the glass adhesive 3a is used)
is the so-called gap. Various glasses with different working humidity and composition have been used to form this gap. If so-called low-melting glass, which has a low working temperature (for example, about 580° C. or lower) is used, bubbles are likely to form and the abrasion resistance is poor, and if bubbles remain in the glass, they may damage the magnetic recording medium. Therefore, so-called high melting point glass, which has a higher working temperature, is used to form this gap. However, with conventional high-melting point glasses, the glass must be heated and melted at a fairly high temperature in order to flow into the gap, which may impair the material performance of the ferrite or cause the ferrite to be eroded by the glass. As shown in Fig. 2, the apex portion 4 may sag and become rounded, making it impossible to ensure the accuracy of the gap depth dimension d, or the gap forming surface 5 may become jagged, resulting in poor linearity of the gap. There were problems such as not being maintained.

In other words, a deep degraded layer is created by the glass adhesive, and when the surface of the magnetic head facing the magnetic recording medium is mirror-polished, the gap length B changes or the linearity of the gap is not maintained. Not only did this have a shape defect in that the accuracy of the gap depth d could not be ensured, but it also had the disadvantage that the magnetic properties of the ferrite itself deteriorated due to exposure to a high temperature atmosphere.

The purpose of the present invention is to eliminate such drawbacks of the prior art,
There is no erosion of the ferrite, and when it is used, for example, to form a gap in a magnetic head, the apex part of the magnetic herad gap does not sag, and the gap forming surface does not become jagged, so the depth of the gap can be reduced. It is possible to form a gap with good length accuracy and sufficient linearity, and because the working temperature can be kept within an appropriate range, there is no deterioration of the magnetic properties of ferrite, and it is possible to form a gap that ensures sufficient linearity. It is an object of the present invention to provide an improved glass composition for ferrite bonding that can be used in combination with a glass adhesive to assemble parts.

The present invention will be explained in detail below. The glass composition for ferrite adhesion according to the present invention is 51032-4.
6% by weight, Pbo 12~22% by weight, Na2O10~
14% by weight, B2O29~13% by weight, Fe2O34~
8% by weight, 720505-3% by weight, A1□031-5
Weight%, MnO 4% by weight or less, ZnO, Cab, MgO
, Cd0 (1 or 2 stacks selected from D)
It has a composition of 4 weight% and 204% by weight or less.

Here, the composition of silicon dioxide (Sin2), which is the main component, is set to 32 to 46% by weight because if it is less than 32% by weight, the working temperature for forming the gap will be less than 650°C; This is because if the weight exceeds the weight, the working temperature for forming the gap will exceed 750°C. The meanings of these temperature ranges are as follows. First, if the working temperature for forming the gap exceeds 750° C., reactions with the ferrite are likely to occur, the gap forming surface is likely to become jagged, and the magnetic properties of the ferrite itself are impaired. Further, if the working temperature for forming the gap 4- is less than 650°C, it becomes impossible to use the glass in combination with other low melting point glasses.

In other words, in the manufacturing process of normal magnetic heads, it is often necessary to use so-called low melting point glass, which has a low working temperature, for bonding ferrite in areas other than gap formation. This is because it becomes impossible to assemble a magnetic head using glass in combination.

Lead oxide (pbo) serves to lower the working temperature and adjust it to an appropriate range. The reason why the composition of lead oxide was limited to 12 to 22% by weight was because if it was less than 12% by weight, it would not be sufficiently effective in reducing the working temperature and the working temperature for gap formation would exceed 750°C. On the other hand, if the content exceeds 22% by weight, the working temperature for forming the gap becomes too low and becomes less than 650°C. Next, sodium oxide (N a20 ) contributes to the thermal expansion coefficient and plays a role in lowering the working temperature.

Here, 10 to 14% by weight of sodium oxide was added because
If it is less than 10% by weight, the thermal expansion coefficient is 80X1077
/℃, which is much smaller than the coefficient of thermal expansion of ordinary ferrite, so when it shrinks after heating and melting, there is a risk of distortion remaining and cracking, etc. If it exceeds 14% by weight, This is because abrasion resistance deteriorates and chemical durability such as water resistance and acid resistance deteriorates. Boron oxide (B203) serves to improve chemical durability and lower working temperatures. Boron oxide 9 to 1
The reason for adding 3% by weight is that it is not very effective if it is less than 9% by weight (because the working temperature for gap formation exceeds 750°C, and if it is added in excess of 13% by weight, chemical In addition, iron oxide (Fe203) is added in a range of 4 to 8% by weight.If such a ferrite component is added to the glass component in advance, the ferrite and It improves the wetting and other fluidity of the glass and suppresses erosion of the glass. However, if it is less than 4% by weight, this effect is hardly produced, and conversely, even if it is added at 8% by weight or more, no improvement in the effect is observed. No. Vanadium pentoxide (■205) improves wettability,
Effective in removing bubbles. The presence of bubbles in the gap area must be avoided as much as possible because cavities are formed during mirror polishing or during subsequent use, and polishing debris, broken debris, dust, etc. accumulate and become a major cause of damage to the magnetic recording medium. . This is because if the amount of vanadium pentoxide is less than 0.5% by weight, there is almost no effect on removing bubbles, whereas if it is added in an amount exceeding 3% by weight, the erosion of ferrite increases, which is undesirable. Aluminum oxide (A103) is effective in improving chemical durability. The reason why the amount added is limited to 1 to 5% by weight is that if it is less than 1% by weight, the effect will be small, and if it exceeds 5% by weight, the wettability of the glass will deteriorate. Manganese oxide (MnO) is effective in improving wear resistance and preventing ferrite corrosion. This manganese oxide is the iron oxide (Fe20
．． ), and as mentioned above, addition of a small amount improves wear resistance and suppresses erosion of ferrite, but when added in excess of 4% by weight, wettability decreases. There is a tendency for things to get worse. Zinc oxide (ZnO)
, calcium oxide (Cab), magnesium oxide (Mg
O), cadmium oxide (CdO) is effective in improving chemical durability. When these are present at the same time as the aluminum oxide, the effect becomes particularly remarkable. If the amount of this type of material added is less than 1% by weight, there is almost no effect of improving chemical durability, whereas if it exceeds 4% by weight, corrosion of the ferrite will increase.

Potassium oxide (K2O) acts to increase the hardness of the glass composition produced. This potassium oxide replaces a portion of the sodium oxide. The reason why the amount of potassium oxide is 4% by weight or less is that if it exceeds 4% by weight, the chemical durability will deteriorate.

When a glass composition for ferrite adhesion within such a composition range is used, an extremely good gap can be formed in a magnetic head as shown in FIG. 3. First, the wettability with the ferrite is extremely good, and the temperature for forming the gap is below 750°C, so the magnetic properties of the ferrite itself will not deteriorate, and there will be no erosion of the glass to the ferrite. Since the apex portion 4 does not sag, the dimensional accuracy of the gap depth d is ensured, and since the gap forming surface 5 is not jagged, the linearity of the gap is maintained, and the dimensional accuracy of the gap length g is also maintained. It is guaranteed.

Next, examples of the present invention are shown in the following table as experimental examples along with comparative examples outside the scope of the present invention. In this table, Experimental Example No. 516p''p9 marked with a book mark is the glass composition for ferrite bonding according to the present invention.

In addition, each composition is expressed here by weight%.

Since manganese-zinc ferrite is usually used as a ferrite material for magnetic heads, the ferrite material to be bonded used in the experiment was also this manganese-zinc ferrite, and its coefficient of thermal expansion was 100 to 135×1.
It is about 0-7/℃. Further, the unit of the thermal expansion coefficient of the glass adhesive is also xlo-7,/°C.

Also, in this table, the gap forming temperature is "suitable" when the working temperature is in the range of 650 to 750℃, and "high" is the working temperature.
is one in which the working temperature is higher than 750°C). Experimental example No. with this mark, 5. 6. The four sides of 8.9 have an appropriate thermal expansion coefficient, do not crack even during the cooling process after heat bonding, have good chemical durability, do not suffer from erosion, and have high hardness. Excellent wear resistance
It was also confirmed that the gap forming temperature was appropriate and a magnetic Rad gap with extremely good dimensional accuracy could be formed.

Although not shown in the experimental example, 7. It has been confirmed that this material has almost the same performance as that of a material containing nO. A similar effect also occurs when the ferrite material to be bonded is nickel-zinc ferrite.

The present invention has been explained above using the case of forming a gap in a magnetic head as an example, but the glass composition for ferrite adhesion according to the present invention can also be used in other applications where the characteristics deteriorate between ferrites or between ferrite and other ceramics. Needless to say, it can be used for bonding without any problems and with high precision.

Since the present invention is a glass composition for adhering ferrite configured as described above, the magnetic properties of the ferrite itself are not deteriorated, the ferrite is not eroded, and the ferrite can be bonded accurately and firmly. In particular, when used to form a gap in a magnetic head, it can significantly improve the shape and size accuracy such as the depth, length, or linearity of the gap. It can have a remarkable effect in that it can greatly contribute to improving the performance of magnetic heads.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an intermediate product in the manufacture of a magnetic head, Fig. 2 is an enlarged explanatory diagram of a gap portion of a magnetic head in the prior art, and Fig. 3 is an explanatory diagram of an intermediate product in the manufacture of a magnetic head. FIG. 3 is an enlarged explanatory view of a gap portion of an assembled magnetic head. 1°° U bar type ferrite core, 2... I bar type ferrite core, 3... Glass adhesive, 4... Apex portion, 5... Gap forming surface, g... Gap length, d...Gap depth. 12- Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1, Si0 32-46% by weight, Pb012-22% by weight, Na2O 10-14% by weight, 82039-13% by weight, Fe2O34-8% by weight, V2O, 0.5-3% by weight, Al2O3 1-5% by weight, MnO4 Weight% or less, Z
A glass composition for ferrite adhesion, characterized in that it comprises 1 to 4 weight% of one or more selected from nO, Cab, MgO, and CdO, and 204% by weight.