JPS62288132A - Production of magnetic head - Google Patents

Abstract

PURPOSE:To obtain a magnetic head having improved environmental resistance without deteriorating magnetic characteristic, by melting and permeating a glass composition, consisting essentially of Bi2O3, SiO2 and B2O3 of specific composition for joining magnetic heads into a magnetic head gap part. CONSTITUTION:A glass rod 3 is obtained from a glass composition, consisting of a principal component, consisting of (A) 13-30mol% Bi2O3, (B) 30-50mol% SiO2 and (C) 1-20mol% B2O3 and satisfying the relationship of >45mol% total of the components (B) and (C) and >2 molar ratio (B/C) and (D) one or more of 1-20mol% Li2O, 1-18mol% Na2O or 1-10mol% K2O and used for joining magnetic heads. The above-mentioned glass rod 3 is then placed on each gap groove 4 of a cut part 2 machined to form a given magnetic passage in a ferrite block 1 and melted while heating at a temperature to give 10<2.5>-10<3>P glass viscosity thereof and then melted, permeated ad adhered to the gap groove 4. The resultant magnetic head member 10 is then cut at each part of a chain line 5 to give a magnetic head front core part 6, which is then bonded to a back core 7, ground and finished to a position of a chain line 8.

Description

[Detailed description of the invention] 3. Detailed description of the invention Industrial applications The present invention relates to a method of manufacturing a magnetic head.

Conventional technology Non-magnetic spacers used in the gap portion of ferrite magnetic heads do not cause mechanical deformation near the gap when sliding with the medium, or wear out of the gap portion to an extreme degree compared to the degree of wear of the head core. It is widely practiced to use a glass material with high hardness (excellent abrasion resistance) to prevent the wear and tear from occurring.

In addition to the infiltration method, sputtering and baking methods are known to form this glass gap, but in cases where a gap width of several tens of micrometers or more is required, such as in an AC erasing head, the infiltration method is used. It is customary.

The glass gap forming method for the erasing head, which is usually carried out by the penetration method, is to process a ferrite block 1 into a predetermined shape and provide a notch 2, as shown in FIGS. 1 and 2. A gap groove 4 of a desired size is formed in the part, and a glass gap rod 3 is placed on top of the groove 4 and melted and infiltrated to form a glass gap.

In this case, unless the glass used has a coefficient of thermal expansion that is almost the same as that of the ferrite core, strain may remain after adhesion near the interface of the bonded part, deteriorating the magnetic properties, or in severe cases, cracks may occur in the glass or ferrite. It may be destroyed by entering.

In addition, the recording media used for magnetic recording have become higher in coercive force due to the recent progress in high-density recording, and the erasing heads that erase these high-coercive-force media must generate a large alternating current erasing magnetic field. Ferrites with high electrical resistance and Mn--Zn type ferrites with relatively high saturation magnetic flux density are used. As is generally known, when a composition of Mn-Zn ferrite that increases the saturation magnetic flux density is selected, the coefficient of thermal expansion increases.

Therefore, in order to match the coefficient of thermal expansion to high saturation magnetic flux density ferrite, the gap of the erase head is formed using alkali silicate glass (PbO-81o2-) containing a large amount of PbO.
R20) is widely used.

Problems to be Solved by the Invention However, if a head with a gap made of glass containing a large amount of PbO is left in a humid environment, the gap will begin to corrode (weather), which will only reduce the adhesive strength. Moreover, there are problems in that the recording medium is damaged by protrusions generated by corrosion, and magnetic powder from the medium adheres to the voids where corroded substances have peeled off, causing noise. Furthermore, since glass containing a large amount of PbO has a low melting point, low viscosity, and a large diffusion coefficient, there is a risk that the molten glass will diffuse into the ferrite grain boundaries at glass working temperatures, deteriorating the magnetic properties.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnetic head with excellent environmental resistance and less deterioration of characteristics.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention provides B i
203. Sio2. The three main components are B2O3, and each of them is Bi2O3: 13-30 (mo+!%) SiO2
: 30-50 (mol%) B2O3:
Within the range of 1 to 20 (mo 2%), and SiOS102 (%) + B2O3: (mol%) > 45
(moffi%) SiO2 (mol%)/B2O3 (mol%)〉2.
0. Na2O, K2O. At least one of the following: 1i2Q: 1 to 20 (mol%) Na20
: 1-18 (mol%) K2O: 1-10 (
mol%) within the range of 2.5 to 103 mol%.
A magnetic head is manufactured by melting and infiltrating the magnetic gap within a temperature range that produces a poise.

In addition, in the above glass composition, B i 203 is 13
~30 moI2% is less than 13 moe% (then the working temperature is higher than 700°C), so the Mn-Zn ferrite core material contains α-Fe which deteriorates the magnetic properties.
This is because 203 tends to precipitate and chemical durability deteriorates, and if the amount exceeds 30 moe%, crystallization tends to occur when melting and permeating.
The reason why 02 is set to 30 to 50 mo2% is because if it is less than 30 moe%, the glass tends to devitrify (deteriorating durability), and if it is more than 50 moe%, the working temperature will be 7.
It becomes higher than 00℃ and the coefficient of thermal expansion becomes too small.
This is because it does not match the thermal expansion coefficient of n-Zn ferrite.Furthermore, B2O3 is set to 1 to 20 moe% for 1 m
This is because if it is less than offi%, the slope of the temperature-viscosity curve becomes gentle and the working temperature becomes higher than 700°C.
This is because if the amount is more than 0 moe%, the weather resistance will deteriorate and the coefficient of thermal expansion will become too small.

By the way, the essential condition for L i 20 and Na2O to contain one component of 20 is to lower the working temperature, and especially if these components are added in combination, the so-called mixed alkali This is because it is possible to lower the melting point and form a glass gap with excellent chemical durability.

In addition, the working temperature for forming the gap was set in the range of 2.5, where the viscosity of the gap glass is 2.5 to 10 poise, from 10 to 10 poise. It becomes easier to diffuse, and conversely, if the working temperature is lowered as the viscosity becomes higher than 103 poise, the glass will flow (((), the workability will decrease, and air bubbles will remain in the glass gap.

Function If the gap is formed using the glass composition and working conditions described above, the magnetic head of the present invention will have excellent environmental resistance and less deterioration of characteristics.

Example Examples of the present invention will be described below.

First, as shown in FIG. 1, the composition shown in Table 1 was prepared in advance on a ferrite block 1 in which notches 2 and gap grooves 4 were processed to form a predetermined magnetic path.
As shown in Figure 1, a glass rod 3 of a specific type is installed at the top of the gap groove 4, and each glass is melted at a working temperature such that the viscosity of each glass is 10 to 10 poise, and it penetrates into the gap groove and becomes fixed. I let it happen.

(The following is a margin) The magnetic head member 10 of FIG. 2 1 with the gap formed in this way is individually cut from the chain line 5 as the 702827 section 6 of the magnetic head, as shown in FIG. The sample was one that was bonded to the processed back core 7 and polished to the position shown by chain [8].
Among the glasses □ in the table, No. 1 to No. 4 have compositions within the scope of the present invention, and No. 5. No. 6 is a conventional glass prepared for comparison, and the core material has a thermal expansion coefficient of 25°C.
120X10'/℃ Mn-Z in the temperature range ~300℃
n-ferrite was used. Next, in order to investigate the degree of diffusion of the glass, which is responsible for forming the gap, into the ferrite in the magnetic head manufactured in this example, an X-ray analysis was performed focusing on the adhesive interface 9 shown in FIG. 3.

Furthermore, in order to investigate the chemical durability of the glass infiltrated into the gap, it was heated at 240°C in an atmosphere of 60°C and 95% relative humidity.
A humidity test for hours was conducted using a constant temperature and humidity chamber. here,
As shown in Figure 3, the evaluation method for the moisture resistance test is to polish to a mirror finish to the position indicated by chain line 8, and use a stylus type surface profile measuring device to examine the surface shape near the glass gap before and after the moisture resistance test. Ta. The state of discoloration of the glass portion was also observed using an optical microscope.

The results of X-ray analysis of the degree of diffusivity of glass with respect to ferrite are shown in FIG. 5 for the magnetic head according to the present invention, and in FIG. 4 for the conventional example.

As can be seen from Figure 4, Pb diffuses from the gap of the high lead-containing silicate glass to a depth of approximately 10 μm into the ferrite region, and in this diffused region, not only the magnetic properties deteriorate, but also the effective The gap width is widening. On the other hand, as shown in FIG. 5, almost no diffusion is observed from the gap portion of the magnetic head according to the present invention. Furthermore, the surface shapes before and after the moisture resistance test are reproduced in FIG. 6 for the magnetic head of the present invention, and in FIG. 7 for a conventional magnetic head in which the gap is made of high lead-containing silicate glass. Note that FIGS. 6(a) and 7(a) show the state before the moisture resistance test, and each figure (b) shows the state after the humidity resistance test. 7th
As can be seen from the figure, the surface shape of high lead-containing silicate glass is extremely rough, which causes noise and noise when sliding with the medium.
There is a risk that this may cause damage to the medium and head.

Furthermore, the surface of the gap glass exhibited a blue interference color, causing a so-called "blue discoloration" phenomenon, resulting in poor appearance. On the other hand, as for the magnetic head of the present invention, as shown in FIG. 6, the glass surface condition after the moisture resistance test was almost unchanged compared to the condition before the test, and no discoloration of the glass surface was observed.

Effects of the Invention As described above, the magnetic head manufactured by the manufacturing method of the present invention has little characteristic deterioration and is highly reliable, making it extremely effective.

[Brief explanation of drawings]

Figures 1, 2, and 3 are diagrams for explaining the manufacturing process of a magnetic head according to an embodiment of the present invention, and Figure 4 shows a conventional magnetic head in which the glass component diffuses from the gap part to the ferrite part. FIG. 5 is a diagram showing the diffusion state in a magnetic head according to an embodiment of the present invention, and FIG. 6 is a cross-sectional view of the surface shape of the helad gap portion of the present invention.
a) is a cross-sectional view before the humidity test, (b) is a cross-sectional view before the humidity test, and Figure 7 is a magnetic head with a gear disk formed from high lead-containing silicate glass, which was prepared as a comparative example to the example of this Serimei. In the cross-sectional views of the surface shape of the gap portion, Figure (a) is a cross-sectional view before the moisture resistance test, and Figure (b) is a cross-sectional view before the humidity resistance test. 1... Ferrite block 2... Notch part 3... Glass rod 4.
...Gap groove 6...Front core part 7
・・・Back core

Claims (1)

[Claims] The three main components are Bi_2O_3, SiO_2, and B_2O_3, and each of them is Bi_2O_3: 13 to 30 (mol%), SiO_2: 30 to 50 (mol%), and B_2O_3: 1 to 20 (mol%). within the range, and SiO_2 (mol%) + B_2O_3 (mol%)>
45 (mol%) SiO_2 (mol%)/B_2O_3 (mol%)>
2, and the remainder is Li_2O.
, Na_2O, and K_2O in the following ranges: Li_2O: 1 to 20 (mol%) Na_2O: 1 to 18 (mol%) K_2O: 1 to 10 (mol%). The viscosity of the glass composition is 10^2^. A method for manufacturing a magnetic head, characterized in that the magnetic head is melted and infiltrated into a magnetic gap within a temperature range of ^5 poise to 10^3 poise.