JPS5836405B2 - Baldfish head - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in heat dissipation of thin film magnetic heads.

The configuration of a conventional magnetic head is as shown in Figure 1.
A ferromagnetic thin film 2 such as permalloy is deposited on the substrate 1.
The electrically insulating layer 3 is formed by electrodeposition, sputtering, etc., and after the desired shape is formed by wet or dry etching, the electrically insulating layer 3 is deposited.

Next, a conductive film 4 is provided by a method such as vapor deposition, electrodeposition, or sputtering, and is etched into a predetermined shape to form an electrically insulating layer 5.
A ferromagnetic circuit has been formed between the upper ferromagnetic layer 6 and the lower ferromagnetic layer 7, and used as a magnetic head.

On the other hand, in order to increase the recording density of thin-film magnetic heads,
Designed with closer head spacing, the shape of the thin film conductor coil for signal recording and playback, which was previously considered, has been simplified.
It has changed from a multi-part type to a one-volume type.

The strength of the magnetic field in the head cap is proportional to the ampere tan of the conductor coil, so if it is a one-turn type, it is generally not possible to use it unless a current of several amperes is passed through the conductor coil during recording. cannot be recorded on recording media such as magnetic tape.

Therefore, in the conventional example, the electrically insulating layers 3 and 5 provided on both sides of the conductor coil 4 are formed of S s O and S t 02, which have low thermal conductivity and are not allowed to flow into the conductor coil 4. The heat generated by the current cannot be sufficiently conducted and discharged.

Therefore, when used for a long time, the conductor coil 4 may melt and break due to self-heating, be oxidized by being attacked by oxygen in the atmosphere due to the high temperature, or due to thermal expansion of the conductor due to the high temperature. However, cracks formed in the insulating layer and leakage occurred, making it impractical.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned conventional drawbacks, it is an object of the present invention to provide a magnetic head that improves the heat dissipation effect of the components in the magnetic head and can be used for a long time.

Among conventionally used insulators such as SiO and SiO2, for example, the thermal conductivity of SiO2 is 0.0 1
4 to 0.14 (W/cIIL-deg), and is a semiconductor.

For example, in Si, the thermal conductivity is 1.5 (W/cyrt
- deg), and the heat conduction is 10 to 100 times better than S s 0 2.

In addition to Si, materials with better thermal conductivity than Si02 include graphite, Ge, InSb, NiO,
AIP, GaP, AISb, GaAs, Garb and In
Substances such as As can be mentioned.

However, some semiconductors have a resistivity of 102Ω or lower, and in this case, sufficient electrical insulation between conductive coils and conductive ferromagnetic layers cannot be obtained, resulting in electrical leakage. or crosstalk between magnetic heads.

Therefore, by oxidizing the surface layer of the conductor coil by a method such as anodizing, heat treatment, or ion implantation, and making the surface layer of the conductor coil an insulator, the ferromagnetic property between the conductor coils and the conductive By obtaining sufficient electrical insulation between the bodies and dissipating the heat generated from the conductor coil by conducting it through the semiconductor layer, the thin film This solves the short life span of magnetic heads and provides a long-life thin film magnetic head.

FIG. 2 is a sectional view of an embodiment of a thin film magnetic head according to the present invention.

A ferromagnetic thin film 8 such as permalloy is formed on a substrate 7 made of glass or the like.
to form the lower magnetic body.

An electrically isolating layer 9 made of a semiconductor is formed so as to cover the lower magnetic body 8, and is deposited using a method such as vapor deposition, electrodeposition, or vapor phase growth.

On top of that, a conductive material such as AI or Cu is deposited using a method such as vapor deposition, a portion of the conductive material is overlapped with the lower magnetic material 8 using a method such as etching, and a method such as anodic oxidation is applied. to form an oxide film.

The thickness of this film may be 1000 angstroms or less.

Next, in the same manner, a conductor such as AI or Cu is deposited using a method such as vapor deposition to obtain a similar shape.

This film is once again oxidized by several hundred angstroms of its surface layer using a method such as anodic oxidation, and a conductor such as AI or Cu having oxidized layers on both sides is used as the bias coil 10.

By forming the oxide layer 11 on the surface layer of the bias coil 10 in this way, the bias coil 10 is electrically insulated from other layers, as shown in FIG.

Next, in the same manner as above, the electrically isolated layer 12
(In this embodiment, a semiconductor is used.

), a signal coil 13, an oxide layer 14, an electrically isolated layer 15, and an upper magnetic layer 16 are formed in this order.

In order to enable the thus formed magnetic head to slide on a recording medium such as a magnetic tape, a protective glass 18 is fixed with an adhesive 17 and wrapped to form a head gap surface 19.

The gap is formed by an upper magnetic body 16 and a lower magnetic body 8, and includes a bias coil 10 and a signal coil 13 within the gap. I'm here.

A rear gap is formed between the magnetic layers 8 and 16 in a portion of the upper magnetic layer 16 far from the gap surface 19, and a magnetic circuit is formed between the upper magnetic layer 16 and the lower magnetic layer 8.

An alternating current bias is applied to the bias coil 10 during signal recording, and when a multi-channel head is constructed, the bias coil 10 is arranged in common to each head so as to generate a common bias magnetic field to each head.

In this way, the current flowing through the heads can be reduced compared to the case where a bias current is caused to flow through each head, and this becomes more effective as the number of channels increases.

The signal coils 13 are formed into separate circuits so as to generate different signal magnetic fields for each head.

Due to the AC bias effect, the signal current for generating the signal magnetic field induced in each head is 1/ compared to the case of non-bias recording.

By making the bias coil 10 common to each head, the total current supplied to the multi-channel magnetic head can be reduced.

However, even in this case, the layer 12 electrically separating the bias coil 10 and the signal coil 13 is made of Si.
If it is made of an insulator such as O or SiO2, the heat generated by the bias coil 10 and the signal coil 13 will raise the temperature of the insulating layer between the two coils, causing wire breakage due to melting, or damage to the insulating layer due to thermal expansion. If the bias current flows into the signal circuit and is grounded through the signal circuit, a sufficient bias magnetic field cannot be obtained in all circuits, making it difficult to record the signal sufficiently. I can't.

This disadvantage is due to the fact that the semiconductor according to the invention is used in the electrically isolating layers 9, 12, 15, which dissipates heat through a thermal conductor rather than an insulator such as SiO or SiO2, and the bias coil 10 and the signal coil 13. , each oxide layer 11
and 14, it is possible to prevent leakage through pinholes that occur during semiconductor formation or defects that occur in the semiconductor layer due to heat generated by both coils 10 and 13, and the coils 10 and 13 are well insulated.

The signal coil 13, the bias coil 10, and the semiconductor layer formed between the upper and lower magnetic layers 8 and 16 electrically separate each layer.

Signal coil 13, bias coil 10, magnetic layer 8
, 16 and the resistivity of a semiconductor, the metal used for the coil is a good conductor such as aluminum or copper, and the resistivity is 1.6 x 1 0-6 to 2.6 x 1.
0-6 (Ω - crIL), and the resistivity of semiconductors is generally said to be 1 0-3 to 1 0-12 (Ω - CrrL).

When Si, NiO, etc. are used for the semiconductor layers 9, 12, 15, the difference in resistivity is 10' to 2.3X105 (Ω-CrIL), so the difference in resistivity is about 1010 times.

The resistance R between the elements is R=0δ (S is the area of the element perpendicular to the direction of current flow, l is the length of the element in the direction of current flow, and δ is the resistivity specific to the element).

Now, for example, the signal coil 13 and the bias coil 1
0 length l is 21n7l1 coil cross-sectional area is 30μm2,
By selecting δ to be 2.6×10 −6 Ω, the resistance values of the bias coil and signal coil can be set to 1 Ω to 2 Ω.

On the other hand, the resistance value of the semiconductor layer insulating between the coils is as follows: element cross-sectional area S is 1000 μm, element length l is 1 μm, δ = 1
If you choose 04Ω/lung, you can easily increase it to IOKΩ or higher.

In addition, the thickness of the oxide layer provided on the surface of the bias coil and signal coil is 0.02μ, and the surface area of both coils is 6X.
When the resistivity is 10'μm2 and the specific resistance δ is 1013Ω·2, the resistivity is about 100MΩ, and the double structure of the semiconductor layer and the oxide layer makes it possible to extremely reduce the probability of pinholes.

Further, since the oxide layer is very thin, heat conduction is good.

As described above, the present invention solves the conventional disadvantage of shortening the lifespan of thin-film magnetic heads due to heat generation caused by current in the coil, which occurred mainly during recording, and provides a long-life thin-film magnetic head. .

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional magnetic head, and FIG. 2 is a sectional view of an embodiment of the magnetic head according to the present invention. 7,18...Glass, 8,16...Magnetic material, 9,12,15...Electrical insulating layer, 10
...Bias coil, 11, 14...
Oxide layer, 13...Signal coil, 17...
...Adhesive material, 19...Head cap surface.

Claims (1)

[Claims] 1. In a thin film magnetic head configured such that magnetic materials are placed opposite to each other on both sides of a conductor layer, and a portion of the magnetic materials sandwich the conductor, at least one of the layers formed between the magnetic thin film and the conductor layer is 1. A thin film magnetic head comprising a semiconductor layer, and a surface of a conductor layer on the side of the semiconductor layer made of an oxide.