JPH0296909A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain the magnetic head which exhibits good corrosion resistance even under high-temp. and high-humidity conditions by composing the essential components of a protective layer of prescribed amounts of TiO2 and one or two kinds of WO3 and MoO3. CONSTITUTION:The essential components of the protective layer 16 are com posed of 20 to 75mol% TiO2 and one or two kinds of 20 to 80mol% WO3 and MoO3. Since the Vickers hardness Hv of this protective layer 16 is in an about 400 to 700kg/mm<2> range, the layer is not too soft and has good matching of a wearing property with generally used amorphous Co systems, 'SENDUST(R)', etc., (Hv is about 650kg/mm<2>). Generation of unequal wear in the magnetic layer is thus obviated. Strains are small and residual stresses are hardly generat ed even if the protective layer 16 is directly formed on the magnetic layer 15 by a sputtering method and, therefore, the peeling of the protective layer 16 does not arise and the protective layer is not deteriorated in properties and resists corrosion well even under the high-temp. and high-humidity conditions. The protective layer 16 does not peel and crack even if the protec tive layer 16 is mechanically worked after the formation of the magnetic layer 15. Reactive etching by a gaseous freon system is possible as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head, and more specifically, to a thin film magnetic head in which a protective layer laminated on a magnetic layer is improved.

[Prior art and problems to be solved by the invention] A thin-film magnetic head has a plurality of (lower and upper) magnetic layers formed of sendust, amorphous, etc. on a substrate made of a wear-resistant material such as ferrite or sapphire. Between the magnetic layers, a coil conductor layer, an insulating layer, etc. made of a conductive metal are repeatedly formed and etched, and patterned into a predetermined shape.

Finally, a protective layer is formed to protect the magnetic layer from wear caused by running the recording medium. Alumina and SiO2 were used as the protective layer.

However, in the above structure, if the protective layer is sufficiently hard compared to the magnetic layer, the wear caused by the running of the recording medium will reach the magnetic layer side more quickly, causing uneven wear on the magnetic layer and causing problems with the spacing.
It is well known that losses occur.

On the other hand, if the protective layer is too soft, the overall wear will be rapid, shortening the life of the head. Therefore.

It is desirable that the hardness of the protective layer is slightly lower than that only between the magnetic layer and the path.

For example, the Vickers hardness of the magnetic layer is Hv-11i00~
When B50kg/-, the protective layer has Hv = 400-
It is desirable to set it within the range of OHkg/-.

Further, the thickness of the protective layer needs to be about 20 to 40 μm or more from the viewpoint of sliding properties of the recording medium and resistance to uneven wear. However, when the thickness reaches this level, the protective layer usually peels off or cracks due to the accumulated internal stress. Therefore, it is necessary to reduce internal stress as much as possible. One effective means to solve this problem is to match the thermal expansion coefficients of the materials that make up the head. However, it has generally been difficult to match the thermal expansion coefficients of the metallic magnetic material and the protective layer.

JP-A-62-16218 discloses a mixture of MgO and SiO2 as a protective layer that can effectively suppress the occurrence of uneven wear. Furthermore.

The composition ratio of MgO and 5i02 is 1 with the concentration of SiO2
By setting it as 0 to 70%, appropriate hardness (Hv-45
It is stated that a desired thermal expansion coefficient of 0 to 850 kg/mj) can be obtained.

However, while this protective layer has the properties basically required for a protective layer as described above, it also does not fully satisfy corrosion resistance and processability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film magnetic head that dramatically improves the problems of the prior art described above.

[Means to solve the problem]

According to the present invention, the present invention includes a substrate, a protective layer having a lower magnetic layer, an insulating layer, and an upper magnetic layer in this order on the substrate, and having an end surface formed on the upper magnetic layer and exposed to the recording medium running surface. In thin film magnetic heads.

The main component of the protective layer is 20 to 75 mol% Ti
O2 and 25-80IIlo1% WO3 and Mo
The above object can be achieved by a thin film magnetic head characterized by having one or two types of No. 03.

[Function and preferred embodiments]

The protective layer of the thin film magnetic head of the present invention has a thickness of 20 to 75 a+o.
1% TiO2 and 25-80 a+o1% WO3
The main component is one or two of M2O3 and M2O3.

One or both of wo and M o Oa are 25 mo
If it is less than 1%, the protective layer becomes harder than a commonly used magnetic layer (more than 700 cg/- in terms of Vickers hardness), uneven wear occurs in the magnetic layer, and conversely, if it is less than 80 mol%
If it exceeds 400 kg/In# in terms of Vickers hardness, the hardness of the protective layer is inappropriately soft.
.

wears out quickly. Therefore, the content of one or both of WO3 and M2O3 is preferably in the range of 40 to 70 mol%.

On the other hand, the protective layer can be formed by a vapor deposition method such as a sputtering method or an electron beam evaporation method.

25 mol of one or two of WO3 and M o Oa
% or more, it is possible to form a protective layer with less strain and residual stress (approximately 0.35 GPa or less) even when sputtering is used, for example. Therefore, the protective layer.

The above method allows direct and stable formation of the magnetic layer.

When the protective layer is formed by sputtering.

Make targets easier to manufacture or obtain.

One or more predetermined sintering aids can be added to the target. Therefore, the protective layer may also contain the sintering aid. The content of the sintering aid in the protective layer is 1
For example, there is no problem as long as the sintering aid has an Io [001% or less of the entire main component of the protective layer and a portion of the TlO2 is replaced in an amount sufficient for sintering T102.

Note that other components may be included as long as they can satisfy the characteristics required for the protective layer, but it is preferable that the total amount of the sintering aid is 10 mol % or less relative to TiO2.

〔Example〕

The present invention will be described in detail below with reference to two drawings.

FIG. 1 is a sectional view showing the structure of one embodiment of the thin film magnetic head of the present invention, and the manufacturing process will be explained based on this figure.

In the figure, a ferromagnetic material of Co--Nb--Zr alloy is deposited to a thickness of 10 μm on a ferrite substrate IO by sputtering to form a lower magnetic layer 11. Next, after appropriately forming a non-magnetic insulating layer 12 made of S I 02 or the like and a coil conductor layer 13 made of Cu, A1, etc. at predetermined positions on the lower magnetic layer 11, the non-magnetic insulating layer 13 including the coil conductor layer 13 is formed. The cross section of 12 is processed by ion milling into a substantially pedestal shape as shown in the figure. Next, a gap layer 14 is formed, and the gap layer 14 is removed from a predetermined position (not shown) where it will be directly connected to the upper magnetic layer 15 to be formed later, and a metal magnetic material of Co-Nb-Zr alloy is sputtered. The upper magnetic layer 1 was attached for 15 μs and joined to the lower magnetic layer 11 at a predetermined position (not shown).
form 5.

Next, the protective layer 16, which is the main part of the present invention, is applied to the upper magnetic layer 15.
form on top of.

The protective layer IB was formed using an RF magnetron sputtering device. As a target, a target having a composition of TiO2 with small pieces (5 mm square) of WO3 appropriately arranged thereon was used. However, the target is a complete Ti
It is estimated that the composition is not O2 but TiO with some oxygen removed.

The Ar (containing 5% O2) gas pressure was 0.4 Pa, the cathode power was 350 W, and the target-substrate distance was 55 mm.

The substrate was cooled with water to form a protective layer with a thickness of 40 μl.

This protective layer contains 0.55 mol of 45 mol% Ti
% of WO3.

After the protective layer 16 is formed as described above, the protective layer 16 is flattened and adhered to the protective plate 19 via the adhesive layer (epoxy type) 18 to form the recording medium running surface 20 as in the conventional method.
A thin film magnetic head, which is an embodiment of the present invention, was fabricated by smoothing the surface.

〔evaluation〕

The hardness of the 1-x protective layer containing m (T t O) (WOa)
Figure 2 shows the results measured by the solid line in Figure 2.

Further, the hardness of the protective layer mainly composed of TiO2-WO3-MoO3 was also measured in the same manner. The results are shown in FIG.

From these figures, it can be seen that the hardness of the protective layer within the range specified in the present invention is better than that generally used as a magnetic layer.

(TiO) on a sapphire substrate with a thickness of 0.31
(WO3) 2 1- with a thickness of 5 μm containing x as a component
x A protective layer was formed using an RF magnetron sputtering device, the warpage of the sapphire substrate was measured, and this was converted into the residual stress of the protective layer. The film formation conditions were the same as in the previous example. This result is shown in FIG. 2 by a broken line.

Further, the main component of the protective layer is TiO2-WO3M o
Residual stress was determined in the same manner as above except that 03 was used. The results are shown in FIG.

From these figures, it can be seen that the residual stress of the substrate on which the protective layer is formed within the range specified by the present invention is extremely small.

(c) Some of the thin-film magnetic heads of one embodiment of the present invention manufactured in the same manner as the manufacturing process of the previous embodiment were mounted on a floppy disk drive and a recording medium (Fujix V
F-HR) for 1000 hours, and uneven wear was observed. Uneven wear was determined by observing interference fringes with an optical flat and examining the level difference between the magnetic layer and the protective layer. As a result, 1 with a protective layer within the range specified in the present invention.
No steps were observed and uneven wear did not occur.

b) The protective layer of the thin film magnetic head of the present invention was heated to 40°C.

Corrosion resistance was tested by leaving it at 90% humidity for one week, but there was no change at all.

〔Effect of the invention〕

The protective layer of the thin film magnetic head of the present invention has a Vickers hardness Hv in the range of about 400 to about 700 kg/-, so it is not too soft and is made of Co-based amorphous, sendust, etc., which are commonly used as magnetic layers. etc. (H
v is about 650 kg/-), and the abrasion matching is good, and uneven wear does not occur in the magnetic layer.

Even if the protective layer is formed directly on the magnetic layer by sputtering or the like, the strain is small and almost no residual stress is generated, so that peeling or cracking of the protective layer does not occur.

The protective layer does not change in quality even under high temperature and high humidity conditions,
Good corrosion resistance.

Even if the protective layer is mechanically processed after being formed on the magnetic layer, the protective layer does not peel or crack. Reactive etching using fluorocarbon gas is also possible.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a thin film magnetic head constructed based on the present invention, and FIG. 2 is a graph showing the mol% of WO3 and the Vickers hardness of 1t.
Figures 3 and 4 show the relationship between v and internal stress.
The figure shows the results of measuring the Vickers hardness and residual stress of a protective layer mainly composed of T iO2W 03M o Oa. ■0... Ferrite substrate. 11...Lower magnetic layer. 13...Coil conductor layer. 15... Upper magnetic layer. 17...Front gap 18...Adhesive layer. 20... Recording medium running surface 12... Nonmagnetic insulating layer. 14...Gap layer. 1B...Protective layer. Part. 19...protective plate

Claims (1)

[Claims] A thin film magnetic head comprising a substrate, a protective layer having a lower magnetic layer, an insulating layer, and an upper magnetic layer sequentially on the substrate, and having an end surface formed on the upper magnetic layer and exposed to a recording medium running surface. The main component of the protective layer is 20 to 75 mol% of T.
iO_2 and 25-80 mol% WO_3 and MoO
A thin film magnetic head characterized by being one or two types of _3.