JPH0369009A - Thin-film magnetic head - Google Patents

Abstract

PURPOSE:To improve heat radiation and to prevent the disconnection of a coil so as to enhance reliability by forming an insulating material supporting the coil of a resin dispersed with AlN or BeO or the ceramics selected from a specific group. CONSTITUTION:The front surface of a slider 7 is coated with an underlying insulating layer 1 and a lower magnetic core 2 is formed of 'Permalloy(R)', etc., in this prescribed region. An insulating layer 3 is formed on the core 2 and the layer 1. The layer 3 is formed of the composite material formed by dispersing the AlN or BeO or the ceramics selected from a group consisting of boron nitride, alumina, titania, silica, beryllia oxide, silicon carbide, and alumina nitride into the resin. The coil 4 is embedded into the layer 3 and an upper magnetic core 5 is formed via the layer 3 thereon. This core is connected to the core 2 via a contact hole. The heat radiation of the coil is improved and the disconnection of the coil is prevented in this way, by which the reliability is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to hard disk drives used as computer peripherals.
The present invention relates to a thin film magnetic head mounted on a HDD (hereinafter referred to as an HDD).

[Background Art] In recent years, as computers have become more sophisticated, HDDs have come to be frequently used as peripheral devices. On the other hand, as typified by laptop-type computers, computers are becoming more high-performance, smaller, and lighter, and there is therefore a demand for smaller HDDs. For example, HDD recording media (media), which were originally 14 inches, are now becoming smaller in diameter, such as 8 inches, 5 inches, 3 inches, and even 2.5 inches. On the other hand, there is a demand for HDDs having a storage capacity equal to or greater than that of HDDs before the diameter was reduced. Therefore, the recording medium must be capable of recording data at extremely high density.

Therefore, in order to perform high-density recording on recording media, magnetic materials suitable for high-density recording have been developed, and recording media have been manufactured in which a magnetic film is deposited on the surface of the member by coating or sputtering. There is. Furthermore, thin film magnetic heads are used for recording and reproducing data in order to cope with higher density.

This thin film magnetic head is manufactured by manufacturing a magnetic core layer on a ceramic wafer such as AlTiC by a method similar to the manufacturing method of IC (integrated circuit) or LSI (large scale integrated circuit).
It is formed by laminating thin films such as a spiral coil layer and an insulating layer.

In this case, the thin film magnetic head is formed using the same film forming process as IC or LSI, so it has excellent dimensional stability, but because it is a thin film, it has the disadvantage that the electrical resistance of the spiral coil layer becomes high. . Therefore, when recording data, it is necessary to cause a large current to flow through the spiral coil to generate a sufficiently strong magnetic field. Furthermore, since only a small current flows through the coil during playback, it is necessary to amplify the signal with an amplifier provided at a subsequent stage.

However, as described above, when recording data, a large current flows through the spiral coil, and a portion of this current is converted into heat by the resistance of the coil. In this case, the coil heats up and reaches a high temperature, and this heat may cause wire breakage (burnout). If the coil is disconnected, it will no longer function as a head, so the magnetic head will have to be replaced. However, in miniaturized HDDs, it is difficult to replace the head, and the HDD itself may have to be discarded.

Therefore, attempts have been made to reduce the resistance value of the coil in order to avoid disconnection of the coil. For example, attempts have been made to use copper or aluminum, which have low electrical resistance, as the material for the coil.

It has also been attempted to increase the number of turns of the coil to improve the magnetomotive force. For example, the magnetic head coils of early HDDs had one layer of 8 turns (8 turns), but recently they have been made with 2 layers of 12 turns (24 turns in total) or 4 layers of 12 turns (24 turns in total). 48 turns) are being manufactured.

Furthermore, as an insulating layer that holds spiral coils, etc., instead of using resin-based insulating materials such as photoresist ink and polyimide, which have excellent coverage and can fill in the steps of the coil, A720i and 5ins, which have high thermal conductivity, can be used. Attempts have been made to use inorganic insulating materials.

[Problems to be Solved by the Invention] However, it cannot be said that selecting the material used for the coil and increasing the number of turns in the coil is sufficient to prevent coil disconnection that occurs due to heat generation in the coil. The problem of wire breakage due to heating of the coil remains unsolved.

In addition, the magnetic head converts digital signals at a frequency of 3 to 10 MHz.
In order to record or reproduce at such a high frequency, a capacitor (inductance) is formed in the magnetic head section. This capacitor acts as a resistance to high-frequency signals, causing current loss. The effect of this capacitor becomes more pronounced as the number of layers of the coil increases.

Furthermore, A1□03 and 5iOz, which are being used for the purpose of improving the thermal conductivity of the insulating layer, have been developed using the vacuum thin film method (
Because it is formed by a dry method, it has poor coverage, and the unevenness of the base and the shape of the coil are transferred to the surface, making it difficult to form the core into a predetermined shape when forming the magnetic core layer on top. There is also the problem that the magnetic head is unable to obtain predetermined magnetic characteristics.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a thin-film magnetic head that prevents disconnection due to heat generation of a coil, reduces parasitic capacitance, and has excellent magnetic properties.

[Means for Solving the Problems] A thin film magnetic head according to the present invention includes an insulating material supporting a coil, wherein the insulating material is aluminum nitride, beryllium oxide, boron nitride, alumina, titania, silica, beryllia oxide,
It is characterized by being a composite material in which ceramics selected from the group consisting of silicon carbide and alumina nitride are dispersed in a resin.

[Function] The inventors of the present application conducted extensive experimental research to obtain a highly reliable thin film magnetic cladding that avoids coil disconnection, and found that aluminum nitride, aluminum nitride, It has been found that resins in which beryllium oxide compounds and ceramics are dispersed are suitable. The present invention was made based on the results of this experiment.

In the present invention, when the insulating material supporting the coil is made of aluminum nitride (A t N), aluminum nitride has superior thermal conductivity compared to A1゜03 and SiO The generated heat is quickly removed. Therefore, disconnection of the coil can be avoided.

In addition, in the present invention, when the insulating material supporting the coil is formed of beryllium oxide (Bed), since this beryllium oxide has superior thermal conductivity compared to A1aO3 and SiO2, Heat is quickly removed. Therefore, disconnection of the coil can be avoided. Also, beryllium oxide is A720. The dielectric constant is lower than that of 5in2 and 5in2, and therefore the parasitic capacitance is reduced.

Furthermore, in the present invention, the insulating material supporting the coil is made of boron nitride, alumina, titania, silica (S
i02) When formed from a resin in which ceramics selected from the group consisting of N beryllia oxide (B e O), silicon carbide (SiC) and alumina nitride (A f N) are dispersed, boron nitride (BN) and Ceramics such as alumina (Ai203) have high thermal conductivity, so resins in which these ceramics are dispersed have excellent thermal conductivity and can avoid disconnection of the fill due to heating.

[Example] Next, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a thin film magnetic head according to an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG.
It is a sectional view taken along the line -■.

The front surface of the slider 7 is coated with a base insulating layer 1 made of a predetermined material. A lower magnetic core 2 is formed of permalloy or the like in a predetermined region of the underlying insulating layer 1. An insulating layer 3 is formed on the lower magnetic core 2 and the base insulating layer 1, and the coil 4 is embedded inside this insulating layer 3. This insulating layer 3 is formed of a composite material in which a ceramic selected from the group consisting of AfN, BeO, etc., or a ceramic selected from the group consisting of boron nitride, alumina, etc., is dispersed in a resin.

An upper magnetic core 5 is formed in front of the coil 4 through an insulating layer 3, and this upper magnetic core 5 is connected to the lower magnetic core 2 through a contact hole provided at the center of the coil 4. There is. Further, both ends of the coil 4 extend laterally and are connected to a coil terminal 4a. The entire surface of the magnetic head is covered with a protective film 6, and the coil terminal 4
Only part a is exposed to the front.

In the thin film magnetic head configured as described above, when recording data on a recording medium, the slider 7 is moved in the radial direction of the recording medium, and the tips of the magnetic cores 2 and 5 are brought into contact with the rotating recording medium. do. Then, when the tips of the magnetic cores 2 and 5 are at predetermined positions relative to the recording medium, data is sent to the coil 4 via the coil terminal 4a. Then, a magnetic field is generated in the coil 4 and magnetizes the recording medium directly under the magnetic cores 2 and 5. This saves the data on the recording medium.

When reproducing data stored on a recording medium, the tips of the magnetic cores 2 and 5 are placed at predetermined positions on the recording medium. Then, a weak current is generated in the recoil 4 of the magnetized recording medium J. Data is reproduced by sending this current to the amplifier via the coil terminal 4a.

Next, the results of actually manufacturing a thin film magnetic head using AfN as an insulating material will be described with reference to FIGS. 1 to 3.

An AfN thin film was formed as the base insulating layer 1 on the front surface of the slider 7 to a thickness of 108 m by sputtering.

Similarly, three layers are provided on both sides of the coil 4 as the insulating layer 3.
An AiN thin film was formed with a thickness of μm. Further, as the protective film 6, an AfN thin film having a thickness of 20 μm was formed by the same method.

The upper magnetic core 5 and the lower magnetic core 2 were formed of permalloy into a predetermined shape. Further, the coil 4 has a thickness of 2μ
It is formed of a copper pattern with a width of 7 μm and the number of turns is 8.

On the other hand, as a comparative example, it has the same structure as the above-mentioned example, and the lower insulating layer 11 insulating layer 3 and protection WX6 are Al2O3.
We prepared a thin film magnetic head composed of:

When the thin film magnetic head of this example was put into a writing state for 5 minutes under the conditions of a writing current of 300 mA, which is several times the normal value, and a frequency of 10M11z, no problems occurred. Note that the normal write current is 50 to 100 mA,
The frequency is 3 to 10 MHz.

When we measured the thermal conductivity of the AfN thin film used in this magnetic head, it was 3201F/! It was extremely large, IIK. On the other hand, when the magnetic head of the comparative example was brought into the writing state under the conditions of a writing current of 90 mA and a frequency of 9 MHz, it became unusable after 3 minutes. When this magnetic head was observed under a microscope, it was found that the copper coil was burnt and a wire breakage had occurred. Also, the A! used for this magnetic head! When the thermal conductivity of the 5ao3 thin film was measured, it was found to be 2.
It was as low as 0 W/mK. It is believed that for this reason, the heat generated in the head was not dissipated, causing the temperature of the coil to rise and causing the coil to become disconnected.

Next, the results of manufacturing a thin film magnetic head using BeO as an insulating material will be described.

A BeO thin film having a thickness of 108 m was formed on the front surface of the slider 7 as a base insulating layer 1 by sputtering. Similarly, as the insulating layer 3, 3 μm is provided on each side of the coil 4.
A BeO thin film was formed with a thickness of m. Further, as the protective film 6, a BeO thin film having a thickness of 20 μm was formed by the same method.

The upper magnetic core 5 and the lower magnetic core 2 were formed of permalloy into a predetermined shape. Further, the coil 4 has a thickness of 2μ
It is formed of a copper pattern with a width of 7 μm and a number of turns of 8.

When the thin film magnetic head of this example was put into a writing state for 5 minutes under conditions of a writing current of 300 mA, which is several times the normal write current, and a frequency of 10 MHz, no problems occurred. When the thermal conductivity of the BeO thin film used in this magnetic head was measured, it was found to be extremely high at 320 W/IIIK.

In addition, the dielectric constant of the BeO thin film at IMHz was measured and was 6.7, which is 6.7 for the same high frequency.
This was smaller than the dielectric constant of the No. 3 thin film, which was 3.3. Therefore, the resistance value (inductance) for this high frequency is 1 μH for the Af20* thin film, whereas the resistance value (inductance) for the BeO thin film is 0.5
It has been halved to μ■. Therefore, the thin film magnetic head of this example operated without any problems even when the data transfer rate was changed from 3 MHz of the conventional (magnetic head using AIQO3) to 4.5 MHz.

Next, the results of manufacturing a thin film magnetic head using a composite material in which ceramics are dispersed in resin as an insulating material will be described.

Since the surface of the substrate (slider 7) is mirror polished, there is no need for flattening. A commonly used as the base insulating layer 1
I'aO'a or 5iOz was formed to a thickness of about 20 μm by sputtering. The insulating layer 3 is made by dispersing 70% by weight of BN powder in a polyimide resin.
Coating was performed using a spin cord to a thickness of 5 μm.

In this case, the surface of the insulating layer 3 was naturally planarized. As the protective film 6, A1aO* is usually used because of its high strength.
Ceramics such as 5iOz and 5iOz are used, and also in this example, the ceramics were formed to a thickness of 20μ.

The upper magnetic core 5 and the lower magnetic core 2 were made of permalloy. The coil 4 is formed of a copper pattern having a thickness of 2 .mu.m and a width of 7 .mu.m, and has eight turns.

On the other hand, as a comparative example, a thin film magnetic head was prepared which had a structure similar to that of the above-mentioned example and in which an acrylic resist was formed as the insulating layer 3 with a thickness of 5 μm using a spin cord.

When the thin film magnetic head of this example was put into a writing state for 5 minutes under the condition that the write current was 30On+A1 frequency was 10 MHz, which was several times the normal write current, no problems occurred. When the thermal conductivity of the insulating layer 3 used in this magnetic head was measured, it was found to be as high as 25 I/mK. On the other hand, the magnetic head of the comparative example has a write current of 90 mA and a frequency of 9 M.
When I put it in a writing state under the Hz condition, it became unusable after 3 minutes. When this magnetic head was observed under a microscope, it was found that the copper coil was burnt and a wire breakage had occurred.

When we measured the thermal conductivity of the insulating layer of this magnetic head, we found that
It was extremely low at 5 W/-. For this reason, it is thought that the heat generated in the head was not dissipated, leading to an increase in the temperature of the coil and causing the disconnection.

Note that the resin used in this example may be any resin that can be made flat by spin cord, etc.
Although not limited to the polyimide resin used in the above embodiments, engineering plastic resins such as polyimide, polyamideimide and polyetherimide, and organic resins such as epoxy and acrylic are suitable. Further, the mixing ratio of ceramic and resin varies depending on the required thermal conductivity, but can be selected within an extremely wide range from several percent to over 90 percent.

[Effects of the Invention] As explained above, according to the present invention, since the insulating layer of the thin-film magnetic head is formed of a resin in which aluminum nitride, beryllium oxide, or a predetermined ceramic is dispersed, It is possible to quickly dissipate the heat to the outside and avoid disconnection of the coil. Therefore, in the recent information-oriented society where computers are frequently used, a highly reliable HDD that can withstand severe use can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a thin film magnetic head according to an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG.
It is a sectional view taken along the line -■.

Claims (3)

[Claims] (1) A thin film magnetic head having an insulating material supporting a coil, wherein the insulating material is aluminum nitride. (2) A thin film magnetic head having an insulating material supporting a coil, wherein the insulating material is beryllium oxide. (3) In a thin film magnetic head having an insulating material that supports the coil, the insulating material is made of a ceramic selected from the group consisting of boron nitride, alumina, titania, silica, beryllia oxide, silicon carbide, and alumina nitride. A thin film magnetic head characterized by being made of a dispersed composite material.