JPH01189012A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To prevent generating a partial abrasion and simultaneously, to realize a thin film magnetic head in which a water resistance us satisfactory by forming a magnetic layer, a coil conductor layer and an insulating layer on a substrate and specifying the composition of a protecting layer to be laminated in a constitution in which the protecting layer is laminated on the magnetic layer. CONSTITUTION:A lower magnetic layer 11 made of a ferromagnetic substance is formed on a ferrite substrate 10, a non-magnetic insulating layer 12 and a coil conductor layer 13 are properly formed on it, thereafter, they are processed in an approximately trapezoid shape, a front gap part 17 is exposed, and a gap layer 14 is formed. Next, an upper magnetic layer 15 is formed on the non-magnetic insulating layer 12, and a protecting layer 16 is formed on it. The composition of the protecting layer 16 is made to contain a SnO2 and an SiO2, the protecting layer 16 is flattened after it is formed, and it is sticked through an adhesive layer 18 to a protecting plate 19. By casing the hardness of the protecting layer to be proper in such a way, the generation of the partial abrasion due to the traveling of a recording medium can be suitably prevented, and simultaneously, the water resistance can be also made satisfactory.

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]

A thin-film magnetic head is made by sequentially forming and etching multiple magnetic layers made of sendust, amorphous, etc., a coil conductor layer made of conductive metal, an insulating layer, etc. on a substrate made of wear-resistant material such as ferrite or sapphire. This process is repeated to pattern the magnetic layer into a predetermined shape, and finally a protective layer is formed to protect the magnetic layer from wear caused by running the recording medium.

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 set to be slightly lower only between the magnetic layer and the path.

For example, the Vickers hardness of the magnetic layer is Hv = 600 to 6
50kg/mm”, the protective layer has Hv = 400~
It is desirable to set it within a range of 600 kg/mm.

Further, the thickness of the protective layer is required to be approximately 20 to 40 μm or more in view of the sliding properties and uneven wear resistance of the recording medium. However, when the thickness reaches this level, the protective layer usually peels off or cracks due to 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 Sin as a protective seed layer that can effectively suppress the occurrence of uneven wear. Furthermore, it is described that by setting the composition ratio of MgO and 8102 to 10 to 70% with 5102 as the concentration, appropriate hardness (Hv=450 to 850) and a desired coefficient of thermal expansion can be obtained.

[Problem to be solved by the invention]

However, as a result of various experiments conducted by the present inventors, it was found that although the above-mentioned Mg OS 102 system has a high degree of freedom in terms of hardness and stress, it is inferior in water resistance and has a major drawback in practical use. That is, the desirable Vickers hardness range (5
50 kg/mm2 or more), the composition ratio of MgO is 70 mol% or more, and in this case, the water resistance is extremely poor and is not suitable for practical use. On the other hand, if the MgO composition is 70 mol% or less, the water resistance improves and is somewhat satisfactory, but it becomes too soft, that is, the Vickers hardness falls into an inappropriate range, and in this case as well, it is not suitable for practical use. I found it.

SUMMARY OF THE INVENTION An object of the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a thin film magnetic head that does not cause uneven wear and has a protective layer that is excellent in water resistance.

[Means to solve the problem]

That is, the above object of the present invention is to provide a thin film magnetic head having a structure in which a magnetic layer, a coil conductor layer, and an insulating layer are formed on a substrate, and a protective layer is laminated on the magnetic layer, the protective layer having a composition of SnO2. This is achieved by a thin film magnetic head characterized by being made of and SiO□.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

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

As shown in the figure, a ferromagnetic material of Co-Nb-Zr alloy is deposited to a thickness of 10 μm on a ferrite substrate 10 by sputtering to form a lower magnetic layer II. Next, the lower magnetic layer 11
A non-magnetic insulating layer 12 made of 5i02 etc. and Cu, A
After appropriately forming the coil conductor layer 13 made of I, etc., it is processed into a substantially trapezoidal shape by ion milling, exposing the lower magnetic layer 11 at the front gap portion 17 and the rear gap portion (not shown), and forming the gap layer 14. Form. Co-coat is deposited on the non-magnetic insulating layer 12 so as to be magnetically bonded to the lower magnetic layer 11 at the front gap portion and the rear gap portion.
Nb-Zr alloy metal magnetic material is sputtered to a thickness of 15 μm.
is deposited to form the upper magnetic layer 15.

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 is formed by electron beam evaporation (degree of vacuum = 1xIQ-2).
A film was formed to a thickness of 30 μm using Pa, substrate temperature = 200° C., and deposition rate = 1000 A/min).

After the protective layer 16 is formed as described above, the protective layer 16 is flattened and bonded to a protective plate 19 via the adhesive layer 18, as in the conventional method.

FIG. 2 shows the relationship between the mol% of SnO and Vickers hardness. Vickers hardness HV=400~60Qkg/mm2
For the hardness range of , the mol% of 5no2 is 1% to 10
It can be seen that it can be obtained in %.

A recording medium was run for 1000 hours on the surface of the thin film magnetic head constructed as described above, and uneven wear was observed. Uneven wear was determined by observing interference fringes using an optical flat and examining the level difference between the magnetic layer and the protective layer. As a result, no step difference was observed in the protective layer having the above composition range.

Furthermore, the internal stress of the protective layer having the above composition range is 1.0×10"
dVn/crI~3. OX 108dyn/c+
At +f, it was found that S]02 was approximately one order of magnitude smaller than that of 02 alone.

Furthermore, as a result of the pure water immersion test, no changes were observed.
It was confirmed that there were no problems with water resistance.

〔Effect of the invention〕

As described above, according to the present invention, by appropriately setting the hardness of the protective layer laminated on the magnetic layer, occurrence of uneven wear due to running of the recording medium can be suitably prevented, and a thin film with good water resistance can be formed. A magnetic head can be obtained, and a thin film magnetic head can be provided which has excellent performance by eliminating the drawbacks of the prior art.

Note that even if a small amount of a third substance other than Sn○2 and 5in2 is added, the effects of the present invention are not impaired.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a thin film magnetic head constructed according to the present invention, and FIG. 2 is a diagram showing the relationship between mol% of 5no2 and Vickers hardness. 10 ferrite substrate, 11 lower magnetic layer, 12 non-magnetic insulating layer, 13-coil conductor layer, 14 gap layer,
15-Top magnetic layer, 16-Protective layer, 17-Front gap portion, 18-Adhesive layer, 19-Protective plate

Claims (1)

[Claims] In a thin film magnetic head comprising a structure in which at least a magnetic layer, a coil conductor layer and an insulating layer are formed on a substrate, and a protective layer is laminated on the magnetic layer, the composition of the protective layer is SnO.
A thin film magnetic head characterized by comprising _2 and SiO_2.