JPS61216109A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To dissipate quickly the heat generated at an electromagnetic conversion part and to improve greatly the record or reproduction properties, by using a carbon film produced by a PI-CVD process with high hardness as a protecting layer. CONSTITUTION:A protecting layer 25 is provided on an electromagnetic conversion part 24 by means of a carbon film produced by a PI-CVD process with high hardness. The upper surface of the layer 25 has recesses/projections of several mu according to the recesses/projections of the part 24. These recesses/ projections are flattened by a grinding treatment by a diamond grindstone, etc. or a lapping treatment. A protecting plate 27 is adhered on the flat surface of the layer 25 via an adhesive layer 26. the adhesion properties can be to improved to the plate 27 owing to the flattened surface of the layer 25, and the generated heat can be quickly dissipated. The carbon of the layer 25 has lower hardness than diamond and can be polished together with the substrate 23 and the plate 27 without causing any problem.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application With the improvement of magnetic recording density, practical use of magnetic heads employing a thin film structure in order to reduce the track width of a magnetic spatula 1 or to create a multi-track configuration. is progressing. The present invention relates to these thin film magnetic heads.

Conventional technology An example of the structure of a conventional thin film magnetic head will be described below.

FIG. 2 is a diagram illustrating a cross section of a thin film magnetic head for recording [Toru Kira, et al.: Thin film magnetic head for PCM recording, Sharp Technology, /17;26 (1983) 97].

A spiral signal winding 3 of approximately 4 tans in one layer is formed on a substrate 1, which is made of a soft magnetic material such as ferrite, and serves as a lower core, with an insulating layer 2 interposed therebetween. Common bias lines 6 are stacked.

A Cu film with a thickness of 2 to 4 μm is used for the bias wire 5 and the signal winding 3 to lower the winding resistance.

A magnetic layer 7 serving as an upper core is formed on the bias line 5 via an insulating layer 6 that also serves as a tip gap layer. As the magnetic layer 7, a Ni--Fe alloy or the like is used. On the magnetic layer 7, there are 10 to 20 layers of 8102 etc. as a protective layer 8.
A non-magnetic protective plate 10 is further bonded with an adhesive layer 9. The upper surface of the protective layer 8 has irregularities of several microns reflecting the irregularities of the electromagnetic transducer layer laminated below the magnetic layer 7, but after flattening these irregularities by polishing, the protective plate 10 is attached. There is.

Next, FIG. 3 shows a cross section of the thin film magnetic head for reproduction at 1006 mm.
].

Substrate 11d: A non-magnetic material such as a soft melting ferrite cap or glass is used, but in the case of soft magnetic high permeability II, it has the effect of shielding the magnetoresistive element (hereinafter referred to as λ4R element). This has the effect of increasing sensitivity. Here, an example using ferrite will be explained. Board 1
1, a bias line 13 is formed with an insulating layer 12 in between, and an MR element 15 is further formed with an insulating layer 14 in between.

The MFt element 16 is a permalloy thin film, and conductive layers are connected to both ends (d in the figure), although not shown.

A magnetic layer 17 with high magnetic permeability is formed on the MR element 16 with an insulating layer 16 interposed therebetween. The function of the magnetic layer 17 is the same as that of the substrate 11, which is to shield the MR element 15 and improve sensitivity. On the magnetic layer 17 is a protective layer 1 such as 5i02.
8 is formed with a thickness of 10 to 2011 m. The upper surface of the protective layer 18 is flattened as in the example shown in FIG. 1, and a non-magnetic protective plate 20 is adhered thereon by an adhesive layer 19.

Problems to be Solved by the Invention In the thin-film magnetic head for recording explained in FIG. However, in a head with a thin film structure, it is difficult to increase the number of turns, and the current value must be increased. As the current value increases,
Joule heat is generated due to the electrical resistance of the winding, so when recording on a magnetic tape, the running of the C2 magnetic tape is stopped and the recording current is passed with the magnetic tape in contact with the tape sliding surface 21. In some cases, the magnetic tape may be damaged by the generated Joule heat. In fact, the magnetic properties of the magnetic layer 7 and the substrate 1 are also deteriorated by the temperature H. Therefore, it is necessary to dissipate this generated heat to prevent the temperature of the magnetic head from rising.

However, as each insulating layer and protective layer 8, SiO or 8102 etc. is generally used by vacuum evaporation, and its thermal conductivity is 0.003 cal 7cm -Se
c -°C, and is a poor conductor of heat. Since each insulating layer is a thin film, the adverse effect is very slight, but the protective layer 8 is thick and it can be said that the increase in temperature of the magnetic head cannot be avoided due to the thermal insulation. .

It is conceivable to make this protective layer 8 of a material with high thermal conductivity, for example, a metal such as Cu, but if such a soft metal is exposed over a wide area on the tape sliding surface 21, the metal will become plastic due to tape sliding. This is unsuitable because the flow may cause the gap in the magnetic head to collapse and cause the magnetic head to malfunction.

It is also conceivable to use ceramic as the g-retaining layer 8. The thermal conductivity of hexalamic is about one order of magnitude higher than that of 5102, so there is a possibility that heat generation may be reduced somewhat. However, ceramic films are generally formed by a method such as sputtering, so the film formation rate is low, and it takes about 10 hours to form the film, making it impractical.

Next, the thin film magnetic head for reproduction shown in FIG. 3 has the following problems.

The output voltage obtained from the MR element is proportional to the current density of the current flowing through the MR element. In other words, if you want to increase the reproduction sensitivity, you just need to let more current flow.

However, if this happens, Joule heat will be generated due to energization, as in the case of the example shown in FIG. In the case of FIG. 3 as well, the material of each insulating layer and the protective layer 18 is SiO or S x 02 similar to that of FIG. 2, and heat radiation is extremely disadvantageous. M
The R element has the characteristic of rapidly generating noise when its temperature rises, and with conventional configurations, it was not possible to pass a large amount of current to increase sensitivity, and it was unavoidable to use it at a low sensitivity. .

The biggest problem common to Figures 2 and 3 is:
The thermal conductivity of the protective layers 8 and 18 is poor, and a protective layer that has excellent wear resistance and thermal conductivity and is easy to form is desired.

As a means to solve the problems of conventional protective layers such as S 10 and S No. 2 as described in ``Means for Solving the Problems'', it is conceivable to use diamond as a protective film. The thermal conductivity of diamond is 1.3 to 2.1 ca for type I diamond.
l 7 cm -'iec ·°C, L-type diamond has a thermal conductivity of about 4.4 cal/cm 5 IIC °C, which exceeds that of metals. Furthermore, diamond has the highest hardness among substances and is extremely chemically stable, so when it is used as a protective layer for a thin-film magnetic head, the protective layer that is exposed on the tape sliding surface will protect the head. It does not deteriorate the wear resistance, but rather can improve the wear resistance.

Many reports have been made regarding techniques for forming diamond thin films.

(References) (1) Namba Yoshitsune: Research on low-pressure synthesis of diamond thin films,
Applied Mechanical Engineering, July 1984 issue (2) Seiichi Matsumoto: Low-pressure synthesis of diamonds, Gendai Kagaku, September 1984 issue (3) Nobuo Setaka: Low-pressure synthesis of diamonds 2 Japan Industrial Technology Promotion Association, Technical data/ g 1s s, 59/6/
20 However, all of these are still at the research stage and have not yet been put into practical use.

We have developed a method to form a highly hard carbon film that exhibits properties close to those of diamond (Black Hero).

et al.: Formation and Evaluation of High Hardness Carbon Films by Plasma Injection CVD Method, Proceedings of the 1985 Spring Conference of the Japan Society of Carbon Diversity, IG; 422).

The method we have developed uses hydrocarbon gas such as methane gas as a material gas, turns it into plasma at a low pressure of 10 to 20 Pa, and injects the plasma or ions in the plasma onto the substrate using an accelerated electric field to heat the substrate. Without,
It is possible to form films at high speeds of up to 5,000 people/minute, and we use plasma injection CVD.
(hereinafter abbreviated as PI-CVD method).

The film formed by the PI-CVD method has SP5 to S
It is made of amorphous carbon in a bonding state similar to that of diamond, including an electron configuration of P, and has a Vickers hardness of 2000 to 3000 Kg/ml, a thermal conductivity of 0,
6 Cal 7cm SeC・℃. Although the specific resistivity and refractive index depend on the film forming conditions, they are each 10
'-10130-cm, approximately 2.0 to 2.4.

The film is basically composed of carbon, but may contain some impurities such as hydrogen.

In other words, if high-hardness carbon produced by the Pl-CVD method is used as a protective layer for a thin-film magnetic head, it is possible to provide thermal conductivity comparable to metal and hardness and wear resistance comparable to ceramic. Therefore, the problems described in the conventional example can be solved.

Function: If a high-hardness carbon film produced by the PI-CVD method is used as a protective layer for a thin-film magnetic head, it has a thermal conductivity comparable to that of metal. It becomes possible to conduct heat, and it becomes possible to flow a large amount of current, thereby making it possible to greatly improve the recording characteristics or reproduction characteristics of the thin-film magnetic head. Furthermore, this protective layer has a hardness comparable to that of ceramic (10%) and wear resistance that is at least the same, so it protects the head even when it slides against the tape and improves the life of the head. .

Further, according to the Pl-CVD method, film formation can be performed at room temperature, and there is no risk of deteriorating the magnetic layer such as permalloy.

Furthermore, since the film formation rate is high, it is easy to carry out the removal on an industrial scale.

Embodiment FIG. 1 shows an embodiment of the present invention. Since the present invention is applicable not only to thin-film magnetic heads for recording and thin-film magnetic heads for reproduction, but also to general magnetic heads in which the electromagnetic transducer is configured with a thin-film structure, the detailed structure of the electromagnetic transducer will be explained below. will be omitted.

An electromagnetic transducer 24 is formed on the substrate 23. The electromagnetic transducer 24 has a structure in which a conductive layer, an insulating layer, a magnetic layer, etc. are laminated. The material of the conductive layer is Au/Cr, C
u, AI, etc. are used. Sin, SiO2, etc. are used as the material of the insulating layer, but here PI-CV
It is also possible to use a high hardness carbon film made by the D method,
It can demonstrate good thermal conductivity.

However, since the high-hardness carbon film produced by the Pl-CVD method is chemically stable, it is difficult to form a pattern by etching or the like, and therefore it is not suitable for use in a complex structure such as the electromagnetic transducer 24.

As the magnetic layer, a Ni--Fe alloy such as permalloy is used. In a normal configuration, the upper surface of the electromagnetic transducer 24 is coated with a magnetic layer. Here, we will discuss the problems when applying the PI-CVD method. Although this method has the various features mentioned above, the adhesion of the film strongly depends on the chemical bonding strength with the substrate material, and it is not possible to form a strong film on any material. . The materials that can form a highly hard carbon film by the Pl-CVD method are as follows.

In fact, very strong bonds are possible with St, Ge, B, and their compounds. Next, Co, Cr, and Fe.

Strong bonding is also possible with iron-type metals such as Ni and Mn, or alloys containing these as main components. Furthermore, Ae.

Metals such as Be, Zr, Hf, V, Nb, Ta, and W, or alloys containing these as main components can also be used as the substrate material.

That is, it is used not as a magnetic layer of a thin-film magnetic head. It is easy to form a high hardness carbon film on a Ni-Fe based alloy by the PI-CVD method, and this can be seen as an application example that makes good use of its characteristics.

On the other hand, materials with which it is difficult to form a high-hardness carbon film using the PI-CVD method include Au, Ag, Cu, and the like. These materials are sometimes used as conductive layers in thin-film magnetic heads, and although it is not preferable to directly form a high-hardness carbon film on this surface by PI-CVD, if it is included in a part of the surface, There is no problem in practical use because it is supported by a film that is strongly attached to other parts. However, if you want to form a film more reliably, it is effective to form a thin layer of SiC or the like as a base layer by sputtering or other means before forming a film using the Pl-CVD method. .

Above the electromagnetic converter 24, as described in -1-, there is a P
A protective layer 25 made of a highly hard carbon film formed by l-CVD is formed. The two surfaces of the protective layer 26 have irregularities of several microns reflecting the irregularities of the electromagnetic transducer 24, but these are flattened by grinding with a diamond grindstone or lapping, and the adhesive layer 26
The protective plate 27 is adhered by. As the adhesive, low-melting glass, epoxy resin, or the like is used. Protective layer 2
By flattening the negative side of 5, the adhesiveness with the protection plate 27 is improved, and heat can be quickly dissipated.

However, even when the upper surface of the protective layer 25 is not flattened, if the protective layer 26 has good thermal conductivity, the heat generated in the electromagnetic converter 24 can be dissipated more quickly than in the conventional example. It is not necessary to flatten the top surface.

The surface of the medium contacting surface 28 is finished to be smooth so as to make smooth contact with recording media such as tapes and disks, but the carbon of the protective layer 25 is soft compared to diamond, and the carbon of the protective layer 25 is soft compared to the substrate 23 and the protective plate 27. There are many problems especially if it is polished at the same time.

Effects of the Invention According to the present invention, by using a high-hardness carbon film formed by the Pl-CVD method as a protective layer, the heat generated in the electromagnetic conversion section can be quickly dissipated, so that a large amount of current can be passed. This makes it possible to significantly improve the recording or reproducing characteristics of thin-film magnetic heads, and is extremely useful for future high-density recording magnetic heads such as perpendicular magnetic recording.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a main part of a thin film magnetic head according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part of a conventional thin film magnetic head for recording, and FIG. 3 is a conventional thin film magnetic head for reproduction. FIG. 3 is an enlarged cross-sectional view of the main part of the magnetic head. 1.11.23... Board, thanks 4. 6. 1
2゜14.16...Insulating layer, 3...Signal winding, 5,13...Bias wire, 7,17...
...Magnetic layer, 8.18°25...Protective layer, 9,
19.26...adhesive layer, 15...MR element, 24...electromagnetic transducer, 10,20°27...
...Protection board. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 /l Kogan A Procedural amendment nt 3 sum 60 i 1.9 sword, 31” '4'! Mr. J'R'I Agency Director 2 Name of invention Thin film magnetic head 3 Person who corrects 41 cases and O) Relationship 9!1' Permission Application Appointment i! Ii 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Name (582) Matsushita Electric Industrial Co., Ltd. Representative Toshihiko Yamashita 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Subject to 6 amendments Column 6 of Detailed Description of the Invention of the Specification, Contents of Supplementary IF (1) "N'1-Fe alloy" on page 2, line 15 of the specification is corrected to "rNi-Fe alloy" -f. (2) Change "2.0 to 2.4" in the 4th line of page 9 to 12.
Corrected to 0-3.0". (3) On page 11, line 12, "bonding force" is amended to "bonding force". (4) It is not used as the first magnetic layer on the 4th to 5th lines of page 12. ” was corrected to ``It is often used as a magnetic layer.''

Claims (2)

[Claims] (1) An electromagnetic transducer is constructed by laminating a conductive layer, an insulating layer, a magnetic layer, etc. on a substrate, and a protective layer containing carbon or carbon as a main component is formed on the electromagnetic transducer. A thin film magnetic head with a protective plate glued on top. (2) The thin film magnetic head according to claim 1, wherein the protective layer is diamond-like carbon formed at low temperature and low pressure using plasma or ions.