JPH041902A - Floating type composite magnetic head - Google Patents

Abstract

PURPOSE:To obtain the floating type composite magnetic head having good memorizing and reproducing characteristics by analyzing the stress state acting on thin magnetic metallic films formed on the magnetic head and selecting the thin magnetic metallic films having the magnetorestriction constant of a range of good magnetic characteristics. CONSTITUTION:The magnetic core which is formed with the thin magnetic metallic films 4 on at least either of the opposite surfaces of a pair of core pieces 5, 6 facing each other via a nonmagnetic gap and is joined with a pair of such core pieces 5, 6 by glass 7 is provided. The magnetorestriction constant of the thin magnetic metallic films 4 is specified to +2 to +8x10<-6>. The magnetorestriction constants of the thin magnetic metallic film are optimized by taking the stresses acting on the thin magnetic metallic films 4 into considera tion in such a manner, by which the recording and reproducing characteristics thereof are greatly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a floating composite magnetic head (hereinafter sometimes referred to as a "magnetic head") that is used in a magnetic disk device by floating it very slightly above the surface of a recording medium. ).

[Prior Art] A floating composite magnetic head uses a disk-shaped magnetic recording disk (
It is used by rotating a magnetic recording medium (magnetic recording medium) and making it float slightly by the airflow generated as a result of this rotation.

FIG. 1 is a perspective view showing an example of a floating type composite magnetic head. The magnetic head 1 is composed of an I-shaped core 6 and a C-shaped core 5, which form part of a slider. ■Type core 6 and C
The detailed structure of the joint with the mold core 5 is shown in FIG. Second
In the figure, a metal magnetic thin film 4 is formed on the opposing surfaces of a C-shaped core 5 and a ■-shaped core 6 made of, for example, Mn-Zn ferrite.
is formed. The type core 6 is also made of Mn-Zn ferrite. The type 1 core 6 and the type C core 5 are glass-bonded with a metal magnetic thin film 4 in between so as to have a gap G. 7 indicates a bonded glass.

[Problems to be Solved by the Invention] As shown in FIG. 1, a floating type composite magnetic head in which a metal magnetic thin film is formed exhibits higher recording and reproducing characteristics than a floating type magnetic head in which a metal magnetic thin film is not formed.

However, as the density of magnetic recording continues to increase, recording media with coercive forces exceeding 12,000e have been developed.
There is a strong tendency for magnetic heads to have narrower tracks with track widths of 16 degrees or less, and narrower gaps. As the above trend progresses, the decline in the recording and reproducing output of magnetic heads becomes more pronounced, and research and development of metal magnetic thin films is progressing in order to improve the recording and reproducing output of floating composite magnetic heads. .

For example, JP-A-62-183101, JP-A-60
There is a description of this in JP-A-95904 and the like.

However, the metal magnetic thin film described in the above publication is
This is a study of the magnetic properties of a single metal magnetic thin film.
No consideration has been given to the stress and magnetic properties of the ferrite that composes the floating magnetic head and the magnetic properties when the ferrite core is combined with the glass (hereinafter referred to as bonded glass) that bonds the ferrite core.

Furthermore, in some thin film magnetic heads having a metal magnetic thin film as the main magnetic path, the magnetostriction constant of the metal magnetic thin film is specified in consideration of the stress acting on the metal magnetic thin film. As one of them, Japanese Patent Application Laid-Open No. 62-229511 has a description specifying that the magnetostriction constant of a metal magnetic thin film is negative in a magnetic induction type thin film head.

However, the publication specifies that the magnetostriction constant of the metal magnetic thin film is negative, and the range in which the magnetostriction constant is specified is completely different from that of the present invention, which specifies a positive range. Furthermore, the same publication relates to a magnetic induction type thin film head in which the main magnetic path is formed by a metal magnetic thin film, and the structure is different from the bulk type magnetic head in which the main magnetic path is formed by Mn-Zn ferrite as in the present invention. They are completely different and cannot be applied as is.

Further, Japanese Patent Application Laid-Open No. 60-74110 describes that in a thin film magnetic head, the permissible range of the magnetostriction constant λS of a metal magnetic thin film is specified as 1λs1≦0.4 X L O-'.

However, in the same publication, in order to prevent the magnetic permeability of the metal magnetic thin film from decreasing due to the stress generated during the manufacturing of the thin film head, the magnetostriction constant of the metal magnetic thin film is set to a certain allowable range close to O. The effect is completely different from that of the invention in which the magnetostriction constant is specified within a certain positive range in consideration of the stress acting on the metal magnetic thin film, and cannot be immediately applied to the invention.

An object of the present invention is to significantly improve the self-recording and reproducing characteristics of a floating composite magnetic head by optimizing the magnetostriction constant of the metal magnetic thin film in consideration of the stress acting on the metal magnetic thin film. .

[Means for Solving the Problems] In the floating composite magnetic head of the present invention, a metal magnetic thin film is formed on the opposing surface of at least one of a pair of core pieces that face each other with a non-magnetic gap in between. Regarding a floating composite magnetic head having a magnetic core in which core pieces are joined by glass, the magnetostriction constant of the metal magnetic thin film is +2 to +
It is characterized by having a size of 8×10-”.

Further, the core piece has an average thermal expansion coefficient of 110 to 130 x 10-7°C at 100 to 400°C.
-Zn ferrite is preferable, and the average coefficient of thermal expansion at 30 to 380°C of the glass joining the pair of core pieces is 90
It is sufficient if it is in the range of ~l l OX 10-''/'C.

Furthermore, the metal magnetic thin film contains 4.6 to 8.0wt of Al.
%, Si is 4.0 to 9.0 wt%, the balance is preferably substantially Fe, and if it is within 2 wt%, at least one of Ti and Ru, and/or 2 to 5 wt% of Cr.
may be contained.

In addition to Fe-Alr-3i-based thin films, the metal magnetic thin films used in the present invention can also be used with the following metal magnetic thin films (1) to (3).

(1) FexAyNz (however, Xty+Z represents the composition ratio as atomic %, A is Hf, Zr, Ta, Nb
, at least one element selected from the group consisting of Ti, N represents nitrogen), and the composition range is 5≦y≦15 3≦2≦20 x+y+z=100 Fe-based group Magnetic thin film (2) Co A CO-based soft magnetic thin film having a composition in the following range: 5≦y≦13 15≦2≦25 x+y+z=100.

(3) In a magnetic thin film consisting of 5 to 15% Ta, 08 to 20% Ta, and the balance Fe in atomic ratio, Fe having a bcc structure and crystals of TaC, Ta, and C coexist in the structure of the magnetic thin film. -Ta-C magnetic thin film.

[Function] In the magnetic head of the present invention, tensile stress is generated in the track width direction of the metal magnetic thin film. By selecting a magnetostriction constant suitable for the tensile stress in the track width direction of the metal magnetic thin film, the magnetic permeability in the gap depth direction is improved, and the recording/reproducing output of the magnetic head is increased.

This will be explained in detail as follows.

The characteristics of the floating composite magnetic head were first evaluated by two-dimensional simulation.

FIG. 3 shows the distribution of magnetic lines of force near the gap when the magnetomotive force is 80 mA.

It can be seen from FIG. 3 that when the metal magnetic thin film is about 1 or 2 μm thick, the magnetic flux is concentrated in the metal magnetic groove lI4 and its vicinity by the I-type core 6 side, and the magnetic flux flows in the gap depth direction.

In the high frequency range where this magnetic head is used, the magnetic permeability of a metal magnetic thin film exhibits a higher value in the hard axis of magnetization, in which spin rotation is the main force, than in the easy axis of magnetization, in which domain wall movement is the main force. That is, it can be seen that in order to make it easier for the magnetic flux to flow in the gap depth direction, the axis of difficult magnetization should be oriented in the same direction.

Figure 4 shows the stress analysis results of a metal magnetic thin film by three-dimensional simulation. In Figure 4, the part surrounded by a solid line is the metal magnetic thin film 4, 5 is a C-shaped core, 6 is a ■-shaped core, and 7 is a metal magnetic thin film. is reinforced glass. The arrows on the metal magnetic thin film 4 indicate the direction and magnitude of the stress acting on the thin film. Tensile stress acts on the entire surface of the metal magnetic thin film, with particularly strong tensile stress in the track width direction. It has occurred.

FIG. 5 shows thermal expansion curves of ferrite, bonded glass, and metal magnetic thin film. As is clear from FIG. 5, among these, the metal magnetic thin film has the largest coefficient of thermal expansion.

In addition, Figure 6 schematically shows the deformation when a metal magnetic thin film is formed on a ferrite substrate and heat treated at a predetermined temperature.6 Figure 6 shows that tensile stress occurs in the metal magnetic thin film. I know what you're doing.

This experimental result agrees with the stress analysis result shown in FIG.

FIG. 7 shows the relationship between the magnetic properties and magnetostriction constant of the metal magnetic thin film formed on the Mn--Zn ferrite core shown in Table 2 N005. The magnetostriction constant was determined by measuring a sample obtained by forming a metal magnetic thin film on a non-magnetic substrate and heat-treating it at a predetermined temperature using an optical lever method. As is clear from FIG. 7, there is a range of the magnetostriction constant in which the magnetic properties of the metal magnetic thin film are improved in the region where the magnetostriction constant is positive. It is estimated that the recording and reproducing characteristics of a floating composite magnetic head having a metal magnetic thin film having a magnetostriction constant in this range are improved by making it easier for magnetic flux to flow in the direction of the gap depth.

As in the present invention, the magnetostriction constant of the metal magnetic thin film is +2 to 18X1.
If it is 0-6, the recording and reproducing characteristics will be extremely high, as shown in FIGS. 8 and 9, which will be described later.

This phenomenon is thought to be caused by the following effect of stress acting on the metal magnetic thin film.

The tensile stress in the track width direction is larger than the stress in the gap depth direction, so considering only the stress energy, if the magnetostriction constant of the metal magnetic thin film is positive, the axis of easy magnetization is in the track width direction, and the axis of easy magnetization is in the gap depth direction. It is thought that the axis of hard magnetization is oriented to the direction of the axis.

In this way, when the axis of hard magnetization is oriented in the gap depth direction, it is estimated that the magnetic permeability of the metal magnetic thin film in the gap depth direction increases in the megahertz frequency band in which the magnetic head operates, and as a result, It is thought that the magnetic flux flows more easily in the direction of the gap depth.

Furthermore, the magnetic head of the present invention has an appropriate coefficient of thermal expansion M
By using n-Zn ferrite and bonded glass, it is possible to firmly adhere the metal magnetic thin film to the ferrite core piece and prevent cracks from occurring in the bonded glass.

Further, the magnetic properties of the metal magnetic thin film are high magnetic permeability and high saturation magnetic flux density, and its corrosion resistance can be significantly improved.

[Example] The invention will be explained in detail below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the overall structure of a floating composite magnetic head according to an embodiment of the present invention. FIG. 2 shows details of the joint between the C-type core piece 5 and the 1-type core piece 6. 1 is M n
-Z These are magnetic materials called a C-shaped core piece 5 and an I-type core piece 6 made of n-ferrite, and the ■-shaped core piece 6 uses the end of a slider. 4 is a Fe-Al-5i thin film deposited on the C-shaped core piece 5. 3 is a window for winding formed between the C-shaped core piece 5 and the I-shaped core piece 6, and a glass part 7 is provided on the top of the window to join the C-shaped core piece 5 and the ■-shaped core piece 6. It is being The shape of the floating composite magnetic head of this example is as follows.

Track width Tw: 14g Magnetic gap length GQ: 0.60° Magnetic gap depth Gd: 6gm Core height: 1.6a+n+This floating type composite magnetic head is manufactured by the following process.

First, a block of M n -Z n ferrite is processed into predetermined dimensions to obtain a C-shaped core block and a -shaped core block.

A metal magnetic thin film is formed on one of the core blocks,
In this example, a metal magnetic thin film is coated on the C-shaped core block by approximately 2-
Formed.

The conditions for forming the metal magnetic thin film are as shown below.

RF power: 400 W Distance between target substrate: 70 mm Substrate temperature: 300° C. Ultimate degree of vacuum: 5×IO-'Pa Gas pressure: 7×10-'Pa Next, the C-type core block and the I-type core block are bonded using glass. A floating composite magnetic head can be obtained by grinding and polishing this bonded block.

The present invention will be explained with reference to the following specific examples based on the above manufacturing method.

Example 1 A Fe-Al-5i thin film having a magnetostriction constant of -1 to +9x10-' as shown in Table 1 is formed on a non-magnetic ferrite substrate, and a C-shaped core block and a ■-shaped core block are bonded. Heat treatment was carried out at temperature.

Table 1 The sample is 3 above the Curie point of Mn-Zn ferrite.
It was heated to 00°C, the magnetization curve was measured, and the coercive force was read. FIG. 7 shows the relationship between the coercive force and the magnetostriction constant of the Sendust film.

As is clear from Figure 7, the coercive force has a magnetostriction constant of +2 to +
It shows a low value in the range of 8x10-', and further shows a significantly low value in the range of the magnetostriction constant from +4 to +6x10-'.

FIGS. 8 and 9 show the relationship between the magnetostriction constant of the metal magnetic thin film and the output and relative margin of the floating composite magnetic head manufactured by the above manufacturing process.

However, the characteristics measurement conditions are as follows.

Media coercive force 12000e Peripheral speed 9.4m/s Flying height 0.17μm Number of turns of magnetic head 21X2 (turn) frequency
LF21 M Hz HF: 4 MHz Under the above measurement conditions, the reproduction output of the floating composite magnetic head shown in Fig. 8 is a high value when the magnetostriction constant of the Fe-Al-3i thin film is in the range of +2 to +8 x 10-'. becomes. Furthermore, the relative margin of the floating composite magnetic head shown in FIG. 9 also shows that the magnetostriction constant of the Fe-Al-5i thin film is +2 to +8×10
The value is high in the range of “.

In addition, Fe-Al-5L corresponding to the magnetostriction constant in the above range
The composition range of the thin film is Al: 4.6-8.0w%, Si:
is 4.0 to 9.0 wt%, with the remainder being substantially Fe. That is, the magnetostriction constant of Fe-Al-5i thin film +2
~+8×10-” range and Al: 4.6-8.0
wt%, Si: 4. O~9゜0wt%, remainder substantially F
A high reproduction output can be obtained in the composition range of e.

Example 2 The manufacturing process of a magnetic head requires a heat treatment process such as glass bonding. In this heat treatment step, the Fe-Al-5i thin film may peel off from the ferrite core due to the difference in thermal expansion coefficient between the ferrite core and the Fe-Al-5i thin film. As shown in FIG. 5, the coefficient of thermal expansion of ferrite is smaller than that of the Fe--Al--Si thin film. Therefore F
The following test was conducted for the purpose of investigating the lower limit of the thermal expansion coefficient of the ferrite core at which the e-Al-5i thin film does not peel off.

Using ferrite having a thermal expansion coefficient of 95 to 135Xlo-'/'C shown in Table 2, the ■-shaped core block described in the manufacturing process above was produced. A 2-thick FeAl-5i thin film was formed on the ■-shaped core blocks having various coefficients of thermal expansion using a magnetron sputtering device. In addition, the composition of the Fe-Al-5i thin film is 85 wt% Fe
, 6 wt%, 12 and 9 wt% Sl, the magnetostriction constant λ
S is +2×10'.

Table 2: ■ type core block with Fe-Al-5i thin film formed,
Heat treatment was performed at a temperature of 600°C for 60 minutes to form Fe-Al
The presence or absence of peeling of the -5i thin film was investigated. The results are shown in Table 3. 0 in the table indicates no abnormality, and Δ indicates F of only the edge of the sample.
This indicates that an abnormality such as peeling occurred in the e-Al-5i thin film, and X indicates that an abnormality such as peeling of the Fe-Al-5i thin film occurred over the entire surface of the sample.

Table 3 It was found from Table 3 that the lower limit of the thermal expansion coefficient of ferrite to which the ferrite and the Fe-Al-5i thin film could be stably attached was l OX I O-'/'C. Further, a ferrite material having a coefficient of thermal expansion exceeding 135XIO-7/°C causes sintering defects in the ferrite manufacturing process, resulting in a significantly low manufacturing yield. Furthermore, ferrite with a coefficient of thermal expansion exceeding 130×10-'/'C has a magnetic permeability peak near room temperature, and the magnetic permeability in the mounted state has a large temperature dependence. Therefore, it is desirable that the thermal expansion coefficient of ferrite is 130×10-'/'C or less. That is, no peeling of the FeAl-5i thin film occurred,
The range of thermal expansion coefficient that allows ferrite material to be manufactured with stable yield is 110 to 130XIO-'/'C.

Example 3 In order to investigate the correlation between the thermal expansion coefficient of the glass that joins the C-shaped core block and the ■-shaped core block and the output of the magnetic head, a magnetic head was created using the bonded glass shown in Table 4. The metal magnetic thin film used in this experiment was +4×10
It is a Fe-Al-3ls film with a magnetostriction constant of -'', and the ferrite has a thermal expansion coefficient of 1 as shown in Table 2.
15Xlo-" ferrite. The characteristics measurement conditions were the same as in Example 1.

FIG. 10 shows the correlation between the thermal expansion coefficient of the bonded glass and the incidence of glass cracks during magnetic core processing.

From the same figure, the glass crack failure rate is determined by the thermal expansion coefficient of 85.
It was found that it increases rapidly below x lO-'/'C and above 119 x 10-'/'C.

In addition, from among the bonded glasses in Table 4, Fig. 11 shows No.
3.4. 5. We selected four types of bonded glasses (No. 6) and showed the characteristics of magnetic heads using each glass.

From the same figure, it can be seen that the recording/reproducing output exhibits a high value when the thermal expansion coefficient of the bonded glass is in the range of 90 to 10×10−7° C.

[Effects of the Invention] The present invention analyzes the stress state acting on the metal magnetic thin film formed in the magnetic head and selects a metal magnetic thin film having a magnetostriction constant in a range with good magnetic properties, thereby achieving high-density recording. In order to cope with this problem, it has become possible to provide a floating composite magnetic head with good recording and reproducing characteristics even in magnetic recording devices where the coercive force of the recording medium has been increased and the track and gap of the magnetic head itself has become narrower. Ta.

[Brief explanation of drawings]

Figure 1 is a perspective view of the floating composite magnetic head, Figure 2 is a detailed view of the vicinity of the gap, Figure 3 is a distribution diagram of magnetic lines of force, Figure 4 is a stress distribution diagram, Figure 5 is a contraction characteristic diagram, and Figure 6 is a diagram of the contraction characteristics. The figure is a thermal deformation behavior diagram, and Figures 7 to 11 are graphs showing measurement results.

Claims (5)

[Claims] (1) A floating composite magnetic head, comprising a pair of core pieces, a glass portion joining the core pieces, and a metal magnetic thin film formed on an opposing surface of at least one of the core pieces,
The magnetostriction constant of the metal magnetic thin film is +2 to +8×10^-^
8. A floating magnetic head characterized in that: (2) The floating type composite magnetic head according to claim 1, wherein the core is made of Mn-Zn ferrite having a coefficient of thermal expansion of 110 to 130 x 10^-^7/°C. Composite magnetic head. (3) In the floating composite magnetic head according to claim 1 or 2, the coefficient of thermal expansion of the glass to which the core pieces are bonded is 9.
A floating composite magnetic head characterized in that the temperature is 0 to 110×10^-^7/°C. (4) In the floating composite magnetic head according to any one of claims 1 to 3, the metal magnetic thin film is made of Fe, Al, and S.
It is an alloy consisting of i, 4.6 to 8.0 wt% Al,
A floating composite magnetic head characterized in that the composition contains 4.0 to 9.0 wt% of Si and the remainder is substantially Fe. (5) In the floating composite magnetic head according to claim 4, the metal magnetic thin film further contains at least one of Ti and Ru and/or 2 to 5 wt% of each of at least one of Ru.
A floating composite magnetic head characterized by containing t%.