JPH0428660B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention is a magnetic head suitable for pressure bonding members used in electronic component materials, particularly ferrite and ceramics of floppy disk drive heads used in computer recording devices, etc. It relates to crystallized glass. Prior Art In general, a head for a floppy disk drive, as shown in the drawing, consists of a recording/reproducing head 1 and an erasing head 2 made of ferrite, a center spacer 3 as a magnetic separation band made of ceramics, and a slider 4 for preventing head wear. The heads 1 and 2 each have a gap portion 5 and a reinforced glass 6. Conventionally, organic adhesives have been used to bond the heads 1 and 2 with the center spacer 3 and slider 4, but the head maintains precise relative positions with the center spacer 3 and slider 4 due to changes in temperature and humidity. 1 and 2 move,
Recently, sealing glass has been used in place of organic adhesives because of the problem of deterioration of properties. However, the sealing glass is susceptible to air bubbles entering the adhesive interface, and if air bubbles are present on the surface of heads 1 and 2 in particular, magnetic powder from the disk will settle there, damaging the magnetic recording surface of the disk and worsening the magnetic properties. There is a problem. In addition to ceramics, crystallized glass is also used for the slider 4, but because of its large surface roughness, it has poor adhesion to the heads 1 and 2, and when adhering to the heads 1 and 2 or the center spacer 3, adhesive must be used. was necessary. In other words, when crystallized glass is generally bonded directly to the heads 1 and 2 or the center spacer 3 using a slider, if the bonding temperature of the crystallized glass is higher than the sealing temperature of the gap portion 5, the organic adhesive of the gap portion 5 and the The sealing glass softens and tends to cause deformation in the gap length and track width of the completed heads 1 and 2, but the yield point of conventional crystallized glass is 850°C or higher, and when used as the slider 4, the bonding temperature This is because the temperature tends to be higher than the sealing temperature of the gap portion 5. Purpose of the Invention The invention was made in view of the above-mentioned problems, and it is possible to directly bond ferrite, ceramics, etc. with strong pressure by low-temperature heating without using an adhesive, as a member used for electronic component materials. The object of the present invention is to provide a crystallized glass for a magnetic head which has little foaming and high mechanical strength. Structure of the Invention The crystallized glass for a magnetic head of the present invention has a weight percentage of
So, SiO ₂ 60-85%, Li ₂ O 7-15%, K ₂ O 1-
7%, Na ₂ O 0.1-7%, K ₂ O + Na ₂ O 2-14%,
_{P2O5 0.1} ~5%, _{Al2O3 1} ~10%, PbO 2.5~10
%, B ₂ O ₅ 0 to 7%, and the total of the above components is 95% or more. The composition range of the crystallized glass for a magnetic head in the present invention is determined as described above for the following reasons. If SiO ₂ is less than 60%, the chemical durability will be poor, and if it is more than 85%, the workability of the glass will be poor. If Li ₂ O is less than 7%, the crystallinity will be low and the coefficient of thermal expansion will be high; if it is more than 15%, the crystallinity will be too high and the yield point will be too high. K ₂ O and Na ₂ O are effective in increasing the thermal expansion coefficient of crystallized glass, but if each is used alone, the glass matrix phase in crystallized glass contains a large amount of alkali components that are not crystal constituents, and the glass Since the matrix phase becomes unstable, in the present invention,
The glass matrix phase is stabilized by the mixed alkali effect caused by the coexistence of 1 to 7% K ₂ O and 0.1 to 7% Na ₂ O, and a crystallized glass with a low yield point can be obtained. When K ₂ O is less than 1%, the yield point becomes too high, and when it is more than 7%, the glass becomes difficult to crystallize. If Na ₂ O is less than 0.1%, the mixed alkali effect will not be exhibited and the yield point will be too high.
When it is more than 7%, the glass becomes difficult to crystallize. If the total amount of K ₂ O and Na ₂ O is less than 2%,
If the yield point becomes too high and exceeds 14%, the glass becomes difficult to crystallize. When P ₂ O ₅ is less than 0.1%, heterogeneous crystals are precipitated and cracks are likely to occur, and when it is more than 5%, the glass tends to undergo phase separation and devitrification. When Al ₂ O ₃ is less than 1%, the glass tends to undergo phase separation, and when it is more than 10%, it becomes difficult to melt the glass. PbO is effective in stabilizing the glass matrix phase and lowering the yield point, but if it is less than 2.5%, the above effects cannot be obtained, and if it is more than 10%, the glass becomes difficult to crystallize. If PbO is more than 15%, the glass becomes difficult to crystallize. When B ₂ O ₃ is more than 7%, cracks tend to form in the crystalline material. In addition to the above-mentioned components, the crystallized glass of the present invention also contains ZnO, MgO, CaO, BaO, SrO, ZrO ₂ ,
It is possible to add up to 5% of each component of TiO ₂ and SnO ₂ . Since the crystallized glass for magnetic heads of the present invention having the above composition has a low yielding point of 630 to 850°C, the surface layer can be heated to a low temperature without changing the gap length or track width of the heads 1 and 2. By softening the matrix phase, ferrite or ceramics can be bonded under pressure while maintaining good parallelism with the heads 1 and 2. Also, the coefficient of thermal expansion is 85~
Since it has a temperature of 135×10 ^-7 /°C, it is particularly suitable for bonding with ferrite. Furthermore, the crystallized glass for magnetic heads of the present invention has
The surface roughness after polishing is less than 300Å,
Therefore, the adhesion is good and the center spacer 3
When used as a disc, it does not easily damage the magnetic recording surface of the disc. The crystallized glass for magnetic heads of the present invention having the above-mentioned characteristics can be used to obtain center spacers 3 and sliders 4 with excellent dimensional accuracy simply by cutting and polishing to a desired size. EXAMPLES The present invention will be explained below with reference to Examples. The following table shows the glass composition and yield point according to the present invention,
It shows the coefficient of thermal expansion and bending strength.

【table】

[Table] Samples No. 1 to 4 in the table were prepared as follows. Mix the glass raw materials to have the glass composition of Sample Nos. 1 to 4, and use a platinum crucible to
After melting at ℃ for 5 to 10 hours, the molten glass is poured into a carbon mold and shaped, placed in an electric furnace maintained at 450 to 500 ℃ for 20 to 30 minutes, and then cooled to room temperature. I twisted it and got some glass. Next, the glass was heated in an electric furnace to 500-550℃ at a heating rate of 120℃/hour, held for 0.5-1 hour, and heated to 700℃/hour.
Heating at a heating rate of 40℃/hour to ~900℃, 0.5~
It was held for 5 hours and then incinerated to room temperature. The main crystal phases of the obtained crystallized glass were lithium disilicate (Li ₂ O.2SiO ₂ ) and α-cristobalite (α-SiO ₂ ). In addition, the above crystallized glass is 10mm x 20mm x 40 ~
Cut and polish to 80μ, sandwich both sides with ferrite, and heat at about 600 to 850℃ to produce about 1 to 5 kg/cm ²
After adhering by applying a pressure of Next, after mirror-polishing the cut surface, we observed it under a microscope and found no bubbles or cracks in the bonded area.
Both were firmly adhered. The yield point in the table is determined from the thermal expansion curve as is well known, and the bending strength is 5φ×50
A blank rod-shaped crystallized glass of mm was measured using a well-known three-point loading method. Effects of the Invention As described above, the crystallized glass for magnetic heads of the present invention has a low yielding point of 630 to 850°C,
By heating at ℃, it can be firmly bonded to ferrite or ceramics under pressure, and it also has low foaming and excellent mechanical strength, making it particularly suitable as the center spacer 3 and slider 4 of floppy disk drive heads. ing. Further, the crystallized glass of the present invention can be bonded to other alloy materials other than ferrite, such as sendust and permalloy, as long as the coefficients of thermal expansion match.

[Brief explanation of drawings]

The drawing is a plan view of a floppy disk drive head. DESCRIPTION OF SYMBOLS 1... Recording/reproducing head, 2... Erasing head, 3... Center spacer, 4... Slider, 5... Gap portion, 6... Reinforced glass.

Claims (1)

[Claims] 1% by weight, SiO ₂ 60-85%, Li ₂ O 7-15%,
K ₂ O 1-7%, Na ₂ O 0.1-7%, K ₂ O + Na ₂ O
2-14%, _{P2O5 0.1-5} %, _{Al2O3 1-10} %,
Contains 2.5 to 10% PbO, ₀ to 7% _B2O3 , and the total of the above components is 95% or more, and the yield point is 630.
~850℃, 30~500℃ thermal expansion coefficient 85~135×
A crystallized glass for magnetic heads characterized by a temperature of 10 ^-7 /℃.