JPS61247639A - Bonding glass for magnetic head - Google Patents

Abstract

PURPOSE:To obtain the titled bonding glass capable of remarkably reducing the presence of gap voids and generation of glass cracks by specifying the composition of the glass consisting of SiO2, B2O3, Al2O3, ZnO, Na2O, K2O, BaO and Fe2O3. CONSTITUTION:Glass composed of, by weight, 30-35% SiO2, 25-35% B2O3, 2-6% Al2O3, 12-21% ZnO, 6-8% Na2O, 6-9% K2O, 0-6% BaO and 2-4% Fe2O3, wherein the total amt. of the components is regulated to 100%, is used for forming the nonmagnetic part of a magnetic head consisting of Mn-Zn ferrite. The terminal expansion coefficient of the bonding glass for a magnetic head is matched with that of the ferrite. Consequently, the generation of glass cracks and presence of voids are simultaneously reduced in the course of cooling after heating to a working temp. and the bonding glass is suitable for the ferrite.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a glass for a magnetic head made of Mn-ZJ7 elite.

(Prior art) The non-magnetic gap of the Mn-Zn 7-elite magnetic head is
It is constructed by heating and melting glass to a temperature slightly above its softening point, pouring it into the void of a ferrite core, and then cooling it to fuse the ferrite and glass. For example, there is glass A having the composition and physical properties shown in Table 1 as a ζ-winding glass.

Air bubbles are generated within the glass during the process of heating the glass to a working temperature range and then cooling it down, and the glass is cooled before the air bubbles can completely escape. At this time, the bubbles generated especially in the gap portion are called gap voids. If this gap void exists, what happens during processing, sliding, etc. of the magnetic head? Magnetic powder gets into the head portion, leading to deterioration in the performance of the magnetic head. Glass A is this gap? Although it is effective as a glass for countermeasures against ferrite, glass cracks are likely to occur because the coefficient of thermal expansion is incompatible with that of ferrite. Therefore, it is effective as a countermeasure for gap roid, and at the same time, does it have a thermal expansion coefficient compatible with that of ferrite? The development of window glass has been awaited.

(Problems to be Solved by the Invention) The present invention lowers the coefficient of thermal expansion of the glass by increasing the amount of SiO2 compared to Glass A, thereby providing a ferrite-compatible glass. be.

・ 3 ・ (Means for solving the problem) In the glass constituting the non-magnetic gap part of the magnetic head composed of Mn-Zn ferrite, Si0 30
-35wt% B2O325~30wt%A22O32
~6w5% znO11~21wt%Na2O6~8w
tq6 to 2O6~9wtq6BaO0~6wt%F
An R-landing glass characterized in that it is composed of 2 to 4 wt % of Si2Os, and the total amount thereof is 100 wt %.

(Example of the invention) The present invention will be explained below based on test examples.

As an example of the present invention, a comparative test was conducted using seven types of glasses shown in Table 2.

・ 4 ・ The ferrite used has a thermal expansion coefficient of 108 and a coefficient of 0-0-7.
(do') (30380℃> Mn-Zn HIP
It is made of ferrite and has the shape shown in Figure 1.

1 is a grooved core, and 2 is a core without grooves. The mirror surface part has a Dia 1μm finish. This ferrite core was heated to 2O2 at 780℃ in a nitrogen atmosphere continuous furnace.
Bake separately. Fig. 2 shows the ferrite cores 1 and 2 facing each other and a glass rod 3 placed in the annular part formed therein, and Fig. 3 shows the ferrite cores 1 and 2 facing each other and a glass rod 3 placed in the annular part formed therein. FIG. 2 is a diagram showing glass fused to ferrite cores 1 and 2. In this test, D
ia 1μm wrapping process and as shown in Figure 3, A
The presence or absence of gap voids and the presence or absence of glass cracks at 80 μm from the pex portion were investigated for each glass. Table 3 shows the results.

Table 3 Gap void existence rate and glass crack occurrence rate (100 samples) As a result of this comparative test, glass for which the sum of gap void existence rate and lath crack occurrence rate is less than 10% is judged to be effective glass. Glass that meets this standard is D-
It was found that there were four types of glass: E-F-G.

In the present invention, the range of SiO2 and At2O3 is limited to 30 to 35 wt% and 2 to 6 wt%, respectively, because if SiO2 is less than 30% or At2O is less than 32%, the softening point decreases and it becomes easier to react with ferrite. As mentioned above, when the Al5O content exceeds 12%, the working temperature of the glass becomes high and the soldering temperature must be increased.This is not desirable because the ferrite deteriorates.

By limiting the range of B2O3 to 25 to 30 wt% (6B2O.If it exceeds 30 wt%, the coefficient of thermal expansion of the glass decreases to such an extent that it is unsuitable for fusion bonding with ferrite.
This is because if O3 is less than 25 wt%, the coefficient of thermal expansion of the glass will increase, which will cause glass cracks, which is not preferable.

Similarly, since Na2O1K2O has a large effect in increasing the coefficient of thermal expansion, if it is outside the scope of the claims, it is undesirable because it tends to cause glass cracks during binding.

Since ZnO has the effect of lowering the coefficient of thermal expansion and increasing the softening point, BaO simultaneously increases the softening point.
It is undesirable that Fe2O3 is outside the scope of the claims, since it deteriorates water resistance and corrosion resistance, and Fe2O3 suppresses the reaction with ferrite and at the same time impairs the wettability of glass.

(Effect of the invention) As detailed above, if the glass of this patent is used, 8
- It is possible to significantly reduce the gap void rate and glass crack occurrence rate of Mn-Zn based HIP ferrite magnetic heads.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of the ferrite, FIG. 2 is a side view of an assembly device including the ferrite and the glass rod, and FIG. 3 is an enlarged view of the fused portion of the ferrite and glass. 1... Core with groove, 2... Core without groove,
3...1μm lap finish surface, 4...Glass rod, 5
... Glass fusion part, 6... Gap is ID, 7.
...Apex Department. Figure 1 Φ Figure 3 Figure 2 [[

Claims (1)

[Claims] The glass constituting the non-magnetic gap portion of the magnetic head made of Mn-Zn ferrite has a composition of SiO_2 30-35 wt% B_2O_3 25-35 wt%
30wt% Al_2O_3 2~6wt% ZnO 11~21w
t% Na_2O 6-8 wt% K_2O 6-9 wt% BaO 0-6 wt% Fe_2O_3 2-4 wt%, the total of which is 100 wt%.