JP2002226258A - Al2O3-TiC-TiB2-based ceramic sintered body and substrate for magnetic head using the same - Google Patents

Abstract

(57) [Problem] To provide a ceramic sintered body excellent in machinability and heat dissipation. SOLUTION: The main component is Al ₂ O ₃ , and (TiC + TiB)
₂ ) 25 to 50% by volume of Al ₂ O ₃ —TiC—
A TiB ₂ based ceramic sintered body, the content of the TiB ₂ is 15 to 40 vol%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sintered body having excellent machinability such as slicing and heat radiation, and more particularly to a hard disk drive or tape drive as a recording device of a computer, an 8 mm VTR,
The present invention relates to a ceramic sintered body used as a magnetic head mounted on an electronic still camera, video floppy (registered trademark), recording and reproduction of digital audio, and the like, and a substrate for a magnetic head.

[0002]

2. Description of the Related Art In recent years, the density of magnetic recording has rapidly increased, and a thin film magnetic head using a magnetic thin film has been generally used as a magnetic head for recording and reproduction.

In such a thin film magnetic head, an insulating film and a thin film element for recording / reproducing a magnetic signal are formed on an end surface of a ceramic slider serving as a substrate, and the slider generates a laminar air flow generated by high-speed rotation of a magnetic disk. It uses the fact that it rides slightly on the surface of the magnetic disk to write and read data on and from the magnetic disk.

The ceramic slider is made of Al ₂ O ₃
-An insulating film made of amorphous alumina is formed on a substrate made of a TiC-based sintered body by a sputtering method, and an MR (Magnet) using a magnetoresistive effect is used as a thin film element.
reliable or GMR (Giant)
A read element such as an MR element and a write element such as a coil film are formed by fine processing by photolithography technology, cut into a predetermined shape, and mirror-finished on the surface to form an ABS (air bearing surface) surface. It is manufactured by performing groove processing by ion milling processing or slicing processing.

The ceramic substrate made of the Al ₂ O ₃ —TiC-based sintered body has excellent chipping resistance and wear resistance when mirror-finished or grooved by slicing, polishing, ion milling, or the like. ,
Since the MR and GMR elements are frictionally charged when sliding in contact with the magnetic disk, and noise is generated when the charge amount is excessively large, the volume specific resistance is set to 10 to prevent this.
^-3 Ω · cm or less. Further, the amorphous alumina film formed on the end face of the ceramic substrate has an effect of imparting insulation and smoothness to the ceramic substrate having conductivity.

However, recently, as the magnetic recording density has been further increased, the flying height of the ceramic slider from the recording surface of the recording medium has been reduced to about 1 microinch, and the slider has been lifted during sliding. When the surface comes into contact with the magnetic disk, frictional heat is easily generated, and the frictional heat causes a temperature change in the MR and GMR element portions,
There is a problem that a thermal asperity phenomenon in which the reading sensitivity of the magnetic head is reduced occurs.

Further, heat generated when the writing element is energized causes
There has been a problem that the element portion protrudes due to thermal expansion and collides with the disk.

Accordingly, a magnetic head substrate is formed by adding α-SiC to the Al ₂ O ₃ —TiC-based sintered body and using a ceramic substrate having a high thermal conductivity to reduce the heat generated in the MR and GMR element portions. Spread over the entire ceramic substrate
There has been proposed a magnetic head in which the heat dissipation of the R and GMR elements is improved.

[0009]

However, a ceramic substrate obtained by adding α-SiC to a conventional Al ₂ O ₃ —TiC-based sintered body can increase the thermal conductivity of the ceramic substrate itself, Due to the difference in hardness from Al ₂ O ₃ and TiC, chipping is likely to occur when machining the ABS or groove by machining such as slicing or ion milling, and the smoothness and surface roughness of the machined surface decrease. Therefore, there has been a disadvantage that the flying height of the slider is hardly stabilized, and accurate reading and writing of information become unstable.

The present invention has been devised in view of the above-mentioned drawbacks, and has as its object to improve the machinability and chipping resistance, improve the heat radiation of the element portion of the magnetic head, and achieve a stable flying height. To provide a magnetic head substrate capable of holding the magnetic head.

[0011]

According to the present invention, Al ₂ O ₃ —Ti is used.
C-TiB ₂ based ceramic sintered body is mainly composed of Al ₂ O _3, a Al ₂ O ₃ -TiC-TiB ₂ based ceramic sintered body which contains 25 to 50 vol% (TiC + TiB ₂₎ , Wherein the content of TiB ₂ is 15 to 40% by volume.

Further, the present invention provides the Al ₂ O ₃ —TiC—
A TiB ₂ ceramic sintered body is used for a magnetic head substrate.

According to the ceramic sintered body of the present invention, Al
_The main component is ₂ O ₃ , and (TiC + TiB ₂ ) is 25-50.
An Al ₂ O ₃ —TiC—TiB ₂ ceramic sintered body in which the content of TiB ₂ is 15 to 4% by volume.
0 is characterized in that the volume%, suitably used as a substrate for a magnetic head, the Al ₂ O ₃ -TiC based ceramic sintered body as a substrate material for conventional magnetic head,
TiB ₂ with excellent machinability and high thermal conductivity as a dispersed phase
As a result, the surface quality of the ceramic sintered body after machining such as slicing and ion milling is high, the chipping resistance is excellent, and the heat conductivity of the ceramic sintered body is high. In addition, it is possible to improve the heat radiation of the MR, GMR element portion and write element portion of the magnetic head, stably maintain the flying height from the magnetic recording surface of the magnetic disk, and obtain a magnetic head having high read and write sensitivity.

[0014]

Embodiments of the present invention will be described below.

The ceramic sintered body of the present invention contains Al ₂ O ₃ as a main component and contains (TiC + TiB ₂ ) in an amount of 25 to 50% by volume.
An Al ₂ O ₃ —TiC—TiB ₂ ceramic sintered body contained therein, characterized in that the content of TiB ₂ is 15 to 40% by volume, and particularly as a substrate for a magnetic head. preferably used, the Al ₂ O ₃ -TiC based ceramic sintered body is a conventional substrate materials for magnetic heads machinability excellent as a dispersed phase, it contains a high TiB ₂ thermal conductivity, chipping resistance, heat dissipation It is a ceramic sintered body having excellent properties.

[0016] Ti contained in the ceramic sintered body
C and TiB ₂ both have conductivity and form a composite dispersed phase, and are contained in the ceramic sintered body in an amount of 25 to 50% by volume as (TiC + TiB ₂ ). (TiC + TiB ₂ )
Is less than 25% by volume, the conductivity of the ceramic sintered body is reduced, and particularly when used as a magnetic head, the MR or GMR due to contact sliding with a magnetic disk during sliding.
The element portion may be frictionally charged, and the charge amount may become excessively large, causing noise. On the other hand, if it exceeds 50% by volume,
The hardness (HV1) of the ceramic sintered body is as high as 25 GPa or more, the load at the time of machining such as ion milling and slicing is rapidly increased, and chipping easily occurs, so that the surface quality of the magnetic head is reduced. And
A stable flying height cannot be obtained, leading to a decrease in reading sensitivity.
Therefore, the content of (TiC + TiB ₂ ) is 25 to 5
It is specified to be 0% by volume, and the volume resistivity of the ceramic sintered body is set to 10 ⁻³ Ω · cm or less to prevent the electrostatic breakdown of the MR element and the GMR element due to the charged charges, and the flying height of the magnetic head is about 1 microinch. Can be stably maintained at a very small value, and a magnetic head with high reading sensitivity can be obtained.

Further, TiB ₂ in the ceramic sintered body is used.
Has a high thermal conductivity of 70 to 80 W / mK, and the thermal conductivity of the ceramic sintered body is improved by the TiB ₂ particles being connected to each other in the ceramic sintered body. It also acts to improve chipping resistance.

The TiB ₂ is contained in the ceramic sintered body in an amount of 1%.
5 to 40% by volume, and the content is 15% by volume.
If it is less than 3, the heat conduction of the ceramic sintered body cannot be sufficiently improved, and the heat dissipation of the MR and GMR element portions is reduced. On the other hand, if it exceeds 40% by volume, TiB ₂ has a higher hardness than Al ₂ O ₃ and TiC constituting the ceramic sintered body, so that chipping resistance and mechanical resistance during mechanical processing such as slicing and ion milling are required. Abrasion is reduced, excellent surface quality cannot be obtained, the flying height of the magnetic head becomes unstable, and the reading sensitivity decreases. Therefore, the T
The content of iB ₂ is specified to 15 to 40 vol%.

Further, Al ₂ O ₃ as the main component of the ceramic sintered body of the present invention, which constitute the residual components of the TiB _2, TiC, the bonding working during sintering of TiB _2, TiC, The purpose is to impart high mechanical strength to the ceramic sintered body itself.

Here, an example of a method for manufacturing a magnetic head substrate using the ceramic sintered body of the present invention will be described.

First, for example, the ratio of Al ₂ O ₃ , TiC and TiB ₂ is set to 6% by weight so that a predetermined composition is obtained.
The raw materials are mixed at a ratio of 3:12:25, and the mixture is pulverized and mixed using a pulverizer / mixer such as a ball mill, and spray-dried with a spray drier or the like to obtain a powder having a uniform shape.

Then, after filling the powder into a hot-pressed carbon mold, the powder is placed in a non-oxidizing atmosphere such as Ar gas at a pressure of 3 ° C.
00 kg / cm ² or more, and a sintering temperature of 1600 to 180
It can be manufactured by hot pressing at 0 ° C. for a firing time of 1 hour or more.

Further, the surface of the ceramic sintered body obtained as described above is smoothed by polishing, and an insulating film such as amorphous alumina is formed on the surface by a sputtering method to manufacture a substrate for a magnetic head. Is done.

Further, in order to form a magnetic head using this magnetic head substrate, a read element such as an MR or GMR element or a write element composed of a coil film or the like is formed on the substrate by photolithography. After passing through a wafer process, the wafer is cut into a predetermined shape by slicing, and mirror-finished on the surface facing the recording medium to form an AB.
After the S-plane is formed, it is manufactured through a slider process of performing rail groove processing using ion milling or RIE processing technology.

The present invention, the Al ₂ O ₃ as a main component as described above, TiC, Al ₂ O ₃ containing TiB ₂ -TiC-
TiB ₂ -based ceramic sintered body, which is suitably used as a magnetic head substrate and a magnetic head, in particular, heat applied to the MR and GMR elements due to frictional heat generated when the magnetic head slides or heat generated from the writing element. Can be efficiently dissipated, the chipping resistance is excellent, the flying height of the magnetic head can be stably maintained, and the reading sensitivity can be improved.

[0026] The present invention is not intended to be limited to the above embodiments, and various modifications as long as it does not depart from the gist of the present invention can be, Al ₂ O ₃ -Ti of the present invention
The C-TiB ₂ ceramic sintered body is useful as a product or component other than the magnetic head.

[0027]

Next, embodiments of the present invention will be described.

As a starting material, Al ₂ O ₃ powder (purity 99.
9% or more, average crystal particle diameter 0.3 μm), TiC powder (purity 99.5% or more, average crystal particle diameter 0.4 μm),
And TiB ₂ powder (purity 99.5% or more, average crystal particle diameter 0.6 μm) were added and mixed at a ratio as shown in Table 1,
These mixed powders are subjected to wet pulverization mixing by a ball mill for 100 hours, and after spray drying, the obtained mixed powders are filled in a hot press graphite mold, and are heated at 1650 ° C. and 350 kg /
1 hour hot press firing at a pressure of ² cm2, φ70m
A ceramic sintered body having a thickness of mx 4 mm was obtained.

From the obtained ceramic sintered body, JISC2
141, a sample was cut out, and the thermal conductivity and the volume resistivity were measured.

A 50 mm × 20 mm × 2 mm thick sample cut out of the sintered body and mirror-finished on its surface was coated with a resin diamond grindstone having a diameter of 96 mm and a width of 0.095 mm at a rotational speed of 10,000 rpm. 50
At a feed rate of mm / min, ten cuttings were performed, the maximum chipping size for each line was measured, and the average value was calculated.

For the calculated chipping size, a value of less than 10 μm which does not affect the quality of the magnetic head is represented by ○, 10 to 2
When 0 μm, Δ is markedly affected by the quality.
The case where the diameter exceeded μm was evaluated as x.

[0032]

[Table 1]

As is clear from Table 1, (TiC + Ti
B ₂ ) contains 25 to 50% by volume (sample N
o. In the range of 3 to 10), the volume specific resistance is 2 × 10 ^−6.
It had a low conductivity of Ω · cm or less and a small chipping size.

On the other hand, when the content of (TiC + TiB ₂ ) is less than 25% by volume (sample Nos. 11 and 12), the volume specific resistance becomes as high as 7 × 10 Ω · cm or more,
When the content exceeds 50% by volume (samples Nos. 1 and 2), it can be seen that the chipping size is large and the chipping resistance is reduced.

Also, as the volume fraction of TiB ₂ increases, the thermal conductivity of the sintered body tends to increase.
_{2 When the} content is in the range of 15 to 40% by volume (Sample Nos. 3 to 8, Sample No. 10), the thermal conductivity shows a large value of 35 W / m · K or more, and the chipping resistance is also excellent. Was.

On the other hand, when the content of TiB ₂ was less than 15% by volume (samples Nos. 9 and 12), the thermal conductivity was 2%.
It was found that the chipping size was increased to 8 W / m · K or less and exceeded 40% by volume (Sample No. 2).

[0037]

According to the ceramic sintered body of the present invention, A
l ₂ O ₃ as a main component, and (TiC + TiB ₂ )
_{0 Al 2 O 3 -TiC-TiB} 2 system is contained vol% a ceramic sintered body, the content of the TiB ₂ is 15
It is characterized by being 40% by volume, and is preferably used as a substrate for a magnetic head, and is used as a dispersed phase in an Al ₂ O ₃ —TiC ceramic sintered body which is a conventional magnetic head substrate material. Excellent workability, high thermal conductivity Ti
Due to the inclusion of B ₂ , the surface quality after mechanical processing such as slicing and ion milling on the ceramic sintered body is high, the chipping resistance is excellent, and the heat conduction of the ceramic sintered body is high. What is needed is to improve the heat radiation of the MR, GMR element portion and write element portion of the magnetic head, stably maintain the flying height from the magnetic recording surface of the magnetic disk, and obtain a magnetic head with high read and write sensitivity. it can.

Claims (2)

[Claims] 1. The method according to claim 1, wherein the main component is Al ₂ O ₃ , and (TiC + TiB)
₂ ) 25 to 50% by volume of Al ₂ O ₃ —TiC—
A TiB ₂ based ceramic sintered body, Al ₂ content of the TiB ₂ is characterized in that 15 to 40 vol%
O ₃ -TiC-TiB ₂ based ceramic sintered body. 2. The Al ₂ O ₃ —TiC—TiB according to claim 1.
Substrate for magnetic head made of ₂ series ceramic sintered body.