JPH0651579B2 - Magnetic head sealing glass - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head sealing glass, and more particularly to a magnetic head sealing glass for sealing cores of a magnetic head made of ferrite to form a gap. Is.

2. Description of the Related Art In the case of a magnetic head using a sealing glass, for example, a magnetic head for a floppy disk, a rod-shaped glass is inserted into the gap between two ferrite cores, and the glass is heated to soften and flow, It is assembled by filling the gap and adhering the ferrite cores together.

The following matters are required for this magnetic head sealing glass.

First, in the manufacture of magnetic head products, several heat treatment steps are carried out, so that it is required that the portion sealed by the sealing glass in the first primary step does not loosely deform in the subsequent heat treatment step. . Conventionally used glass having a low melting point and a low melting point does not meet this requirement because it undergoes softening deformation in the heat treatment step after primary sealing. Therefore, a glass having a high melting point with a high sealing temperature is required, but in the conventional high melting point glass, the surface of the ferrite to be sealed is eroded by the glass, or the glass component is diffused into the ferrite to form a gap forming surface. There is a problem that the effective gap length is changed due to erosion or the linearity of the gap cannot be obtained, so that the magnetic characteristics of ferrite are deteriorated. In addition to the above, the glass for magnetic head sealing has high hardness and good wear resistance, and the coefficient of thermal expansion is compatible with ferrite, so that large residual strain does not occur in the cooling step after sealing and crack cracking does not occur. In addition, it is required that the glass be sufficiently flowable without bubbles to be wetted with the ferrite and that the glass is chemically durable so that the glass does not deteriorate because water or alkaline liquid is used in the manufacturing process of the magnetic head. To be done.

OBJECT OF THE INVENTION The present invention provides a glass that satisfies all the above requirements. That is, according to the present invention, although the sealing temperature is high and the melting point is high, erosion does not occur on the gap forming surface of the ferrite, so that the gap length accuracy is good and the linearity is sufficiently secured, so that the magnetic characteristics of the ferrite are deteriorated. It is an object of the present invention to provide a glass for magnetic head encapsulation, which does not cause wear, has good chemical resistance, and has no bubbles, cracks, or cracks.

Configuration inventor's invention, a result of our extensive studies for achieving the above object, SiO _{2 glass, Al 2 O 3, B 2} O 3, BaO, ZnO, Na 2 O, K
It has been found that the above-mentioned requirements for a magnetic head sealing glass can be satisfied by comprising each component of ₂ O, MnO ₂ and Fe ₂ O ₃ and by adjusting the amount of each component within a limited range. . The characteristic feature of the glass of the present invention is that Pb contained in order to enhance the fluidity and leakability of the glass compared to the conventional ones.
On the other hand, O changes wear resistance and chemical durability,
By avoiding the inclusion of that component, and by incorporating Fe ₂ O ₃ and MnO ₂ , the glass comes close to the composition of ferrite, thus suppressing mutual diffusion, preventing ferrite erosion, suppressing bubble generation and flowing. It is in the place where the sex is improved.

That is, the glass for sealing of the present invention is represented by weight%,
O ₂ 35.0-55.0%, Al ₂ O ₃ 1.0-6.0%, B ₂ O ₃ 7.0-22.0
%, BaO 5.0 to 13.0%, ZnO 5.0 to 18.0%, Na ₂ O 5.0 to 1
_{5.0%, K 2 O1.0~8.0%,} MnO 2 0.2~4.0%, Fe 2 O 3 1.0~7.
It has a composition of 0%.

The content of each component in the present invention is limited as described above for the following reason.

SiO ₂ is a component effective in adjusting the coefficient of thermal expansion to that of ferrite, and its content is 35.0 to 5
It is 5.0%. If it is less than 35.0%, the chemical durability becomes poor and the devitrification of the glass becomes large. If it exceeds 55.0%, the fluidity of the glass will be poor, and the sealing temperature will be too high, and the ferrite surface will be significantly corroded.

Al ₂ O ₃ is a component effective in improving chemical durability,
Its content is 1.0-6.0%. If it is less than 1.0%, the above effect cannot be obtained, and if it is more than 6.0%, the sealing temperature becomes high and the fluidity deteriorates, resulting in bubbles in the glass.

B ₂ O ₃ is a component that adjusts the thermal expansion coefficient, prevents cracks, reduces residual strain, and enhances fluidity, and its content is 7.0 to 22.0%. If it is less than 7.0%, the sealing temperature becomes high and the fluidity deteriorates,
If it exceeds 22.0%, the sealing temperature will be too low and the chemical durability will be poor.

The two components BaO and ZnO have the effect of increasing the fluidity of the glass without increasing the coefficient of thermal expansion, and the content of each component is BaO 5.0-
13.0% and ZnO 5.0-18.0%. When BaO is less than 5.0%, the sealing temperature becomes too high and the fluidity deteriorates. If it is more than 13.0%, the glass tends to devitrify, so its content is 5.0 to 13.0%. ZnO is 5.0%
If it is less, the sealing temperature will be too high and the chemical durability will be poor. If it is more than 18.0%, devitrification becomes strong and ferrite erosion becomes large.

The two components of Na ₂ O and K ₂ O are effective in adjusting the thermal expansion coefficient and the sealing temperature, and Na ₂ O is 5.0 to 15.0% and K ₂ O is 1.0 to 8.0%. When Na ₂ O is less than 5.0% and K ₂ O is less than 1.0%, the sealing temperature becomes too high and the fluidity deteriorates. Also Na ₂ O is 15.0
%, K ₂ O is more than 8.0%, the coefficient of thermal expansion becomes too high, and the chemical durability and wear resistance deteriorate.

2 component of MnO _2, Fe ₂ O ₃ prevents erosion of the ferrite surface, has the effect of improving the fluidity suppresses the generation of air bubbles, the content of each MnO ₂ 0.2 to 4.0%, Fe ₂ O ₃ 1.0-
It is 7.0%. If MnO ₂ is less than 0.2%, the above effect cannot be obtained, and if it is more than 4.0%, the generation of bubbles increases and the fluidity also deteriorates. If Fe ₂ O ₃ is less than 1.0%, the above effect cannot be obtained, and if it is more than 7.0%, the ferrite surface is highly eroded and the fluidity is deteriorated.

Examples The present invention will be described below with reference to examples.

Sample Nos. 1 to 6 in the following table are Examples showing the present invention, Sample No.
Reference numerals 7 and 8 are comparative examples showing conventional products.

In the above table, the crack generation was evaluated using the Mn-Zn system, which is usually used as a ferrite material for magnetic heads, in the thermal expansion coefficient (30
Up to 300 ° C) 90 × 10 ^-7 / ° C ferrite 10 × 10 × 5 mm
Processed into a sample piece, and put a 5x5x5mm plate-shaped glass sample on it, hold it at 750 ° C for 30 minutes and heat it, and then cut and polish it to see the cross section of ferrite and glass with a microscope. The observation was performed and the presence or absence of cracks was confirmed. The evaluation method for ferrite erosion and bubble generation is to insert a rod-shaped (0.5φ x 10 mm) glass material between the above ferrite sample pieces and add a load of about 1 kg / cm ^{2 in} the electric furnace. After heating at 750 ° C. for 30 minutes to bond, the cross-section was observed by using an electron microscope to observe whether the glass was eroding ferrite and whether there were bubbles in the glass.

The Vickers hardness was measured by using a 20 × 20 × 5 mm plate glass sample and applying a load of 200 g to the hardness meter. In the chemical durability test, 2.85 g of glass powder having a particle size of 500 μ was heated in boiling water for 1 hour, and then the weight loss value was obtained in% by weight.

The following is clear from the results in the above table. Sample No. 7 had an excessively high coefficient of thermal expansion and an excessively low sealing temperature, and had cracks, erosion of ferrite and bubbles, and also had low Vickers hardness and poor chemical durability.
Further, sample No. 8 had no problem in terms of thermal expansion coefficient and sealing temperature and did not cause cracks, but it suffered from ferrite corrosion and bubbles, and had low Vickers hardness and poor chemical durability. On the other hand, sample No. 1 of the present invention
~ 6 has a coefficient of thermal expansion that matches that of ferrite,
High sealing temperature, cracks, ferrite erosion,
No bubbles were generated, the Vickers hardness was high, and the chemical durability was good.

EFFECTS OF THE INVENTION As described above, the glass for sealing a magnetic head of the present invention has a coefficient of thermal expansion matching that of ferrite, so that even when bonded to ferrite, residual strain is small and cracks are unlikely to occur. Further, since it does not erode the gap forming surface of the ferrite, does not generate bubbles, and has high hardness, it is excellent in abrasion resistance, and also has good chemical durability, which is most suitable as a glass for sealing a magnetic head.

Claims (1)

[Claims] 1. A weight percentage display of SiO ₂ 35.0 to 55.0%, Al ₂ O
₃ 1.0 to 6.0%, B ₂ O ₃ 7.0 to 22.0%, BaO 5.0 to 13.0%, Zn
O 5.0 ~ 18.0%, Na ₂ O 5.0 ~ 15.0%, K ₂ O 1.0 ~ 8.0%, Mn
Glass for magnetic head sealing consisting of O ₂ 0.2 to 4.0% and Fe ₂ O ₃ 1.0 to 7.0%.