JPS60186435A - 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 magnetic 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 V2O5, (G) 1-5wt% of Al2O3, (H) 1-4wt% of at least one from ZnO, CaO, MgO and CdO and (I) less than 0.4wt% of K2O.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass composition used for bonding ferrite, and is not particularly limited to the present invention. It is related to.

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 the information recorded on the magnetic recording medium by detecting that the residual magnetic flux of the magnetic recording medium enters from the gap portion. ing.

Such a magnetic head has a cross section U as shown in FIG.
Ferrite core shaped like a letter (U-bar type ferrite core)
1 and a ferrite core 2 having a rectangular cross section (parallel type ferrite core) are bonded and integrated at their joints using glass adhesives 3a and 3b, and then thinly sliced and assembled.

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. A variety of glasses with different working temperatures and compositions have been used to form the 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, making it difficult to maintain the linearity of the gap. There were problems such as not being able to drip.

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 g 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,
When the ferrite is not eroded and is used, for example, to form a gap in a magnetic head, the t! The gap formation surface does not become jagged or jagged, so it is possible to form a gap with good gap depth or length accuracy and sufficient linearity. Since it can be kept within this range, there is no deterioration of the magnetic properties of ferrite.
It is an object of the present invention to provide an improved glass composition for ferrite bonding that can be used in combination with other low-melting point glass adhesives to assemble parts.

The present invention will be explained in detail below. The glass composition for ferrite adhesion according to the present invention contains 32 to 46% by weight of 5IO23-, 12 to 22% by weight of PbO, and Na2O.
10-14% by weight, 82039-13% by weight, Fe2O
34-8% by weight, 720505-3% by weight, Al2O3
1-5% by weight, Z no , CaO.

It has a composition consisting of 1 to 4% by weight of one or more selected from MgO and CdO, and 204% by weight or less.

Here, the composition of silicon dioxide (Si This is because if the amount exceeds 750° C. by 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 tend to occur, the gap forming surface tends to become jagged, and the magnetic properties of the ferrite itself are impaired. In addition, the working temperature for gap formation is 650℃.
If the temperature is less than 0.degree. C., the glass cannot be used in combination with other low melting point glasses.

41 In other words, in the manufacturing process of normal magnetic heads, it is often desired to use so-called low melting point glass, which has a low working temperature, for bonding ferrite in areas other than gap formation, and if there is a temperature difference of about 200 degrees Celsius, This is because it becomes impossible to assemble a magnetic head using low melting point glass.

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 is because if it is less than 12% by weight, it will not be sufficiently effective in reducing the working temperature and the working temperature of the gap forming hole will exceed 750°C. On the contrary, 22% by weight
This is because if the temperature exceeds 650° C., 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 coefficient of thermal expansion is 80X10-7
/℃, 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 temperature. Boron oxide 9 to 1
This is because if it is less than 9% by weight, it will not be very effective and the working temperature for gap formation will exceed 750°C, and if it is added in excess of 13% by weight, it will cause chemical damage. This is because durability becomes extremely poor. Furthermore, iron oxide (Fe203) is added within a range of 4 to 8% by weight. If such a ferrite component is added to the glass component in advance, the wettability and fluidity with the ferrite will be improved, and the glass will have the effect of suppressing erosion.

However, if it is less than 4% by weight, the effect is hardly produced.
On the other hand, even if 8% by weight or more is added, no improvement in the effect is observed. Vanadium pentoxide (■205) improves wettability and is effective in removing bubbles. Avoid the presence of bubbles in the gap area as much as possible, as cavities will be formed during mirror polishing or during subsequent use, and the polishing layer, damaged layer, dust, etc. will accumulate and cause the magnetic recording medium to tint. Must be.

This is because if vanadium pentoxide is added in an amount 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, ferrite erosion increases, which is not preferable. 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. Zinc oxide (ZnO), calcium oxide (CaO), magnesium oxide (MgO), and cadmium oxide (CdO) are effective in improving chemical durability. The effect becomes particularly remarkable when these are present simultaneously with the aluminum oxide. If the amount of this type of material added is less than 1% by weight, there will be little effect of improving chemical durability, and if it exceeds 4% by weight, corrosion of the ferrite will increase. Potassium oxide (K 2 O) acts to increase the hardness of the glass composition produced.

This R-hydride potassium 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. Incidentally, to give a concrete example of the effect of adding potassium oxide, according to experimental results, the Vickers hardness was about 510 without the addition, but it increased to about 550 with the addition of about 2% by weight. It has been confirmed that the amount increases by 7% or more.

When a glass composition for ferrite adhesion within such a composition range is used, an extremely good gap can be formed in magnetic rad as shown in FIG. 3. First, the wettability with the ferrite is extremely good, and the working humidity for gap formation is 750°C or less, so the magnetic properties of the ferrite itself do not deteriorate, and there is no erosion of the glass to the ferrite. Since no sag occurs in 4, 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 ensured. It is.

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. Experimental examples Nos. 5, 7, and 8 marked with * in this table are glass compositions 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 Xl0-7/°C. When the gap forming temperature is "appropriate", it means that the working temperature is in the range of 650 to 750°C, and when it is "high", the working temperature is higher than 750°C.

Experimental example No. 5) 7 with this mark in this table
The second side of p8 has an appropriate thermal expansion coefficient, and no cracks appear even during the cooling process after heat bonding.
It has been confirmed that it has good chemical durability, does not cause corrosion, has high hardness, has excellent wear resistance, and has an appropriate gap formation temperature, making it possible to form a magnetic held gap with extremely good dimensional accuracy. Although not shown in the experimental examples, it has been confirmed that a material to which MgO or CdO is added has almost the same performance as a material to which ZnO is added. Further, a similar effect occurs when the ferra foil material to be bonded is nickel-submarine ferrite.

The present invention has been described above using the case of forming a gap in a magnetic head as an example, but the glass composition for ferrite bonding according to the present invention can also be used in other applications such as bonding between ferrites, a certain δ-bow elite, and other ceramics. Needless to say, it can be used for precise bonding without deterioration of properties.

Since the present invention is a glass composition for adhering ferrite configured as described above, it does not deteriorate the magnetic properties of the ferrite itself, does not corrode the ferrite, and can bond the ferrite accurately and firmly. It has the excellent effect of being able to be bonded, and particularly when used to form a gap in a magnetic head, it can significantly improve the shape and size accuracy of the gear, such as depth, length, and linearity. This can be extremely effective in that it can greatly contribute to improving the performance of the magnetic head.

[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 diagram of a gap portion of the assembled magnetic head. DESCRIPTION OF SYMBOLS 1... U bar type ferrite core, 2... Bar type ferrite core, 3... Glass adhesive, 4... Apex part, 5... Gap forming surface, g... Gap length , d... Gap depth. Patent applicant Fuji Electrochemical Co., Ltd. Agent Shigeru Estimate 12- Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1, 3i0 32-46% by weight, PbO 12-22% by weight, Na2O 10-14% by weight, B2O39-13% by weight, Fe2O34-8% by weight, V2O, 0.5-3% by weight, Al2O3 1-5% by weight, ZnO ,Cab,Mg
One or two or more selected from O, CdO 1~
4% by weight, and 204% by weight or less.