JP2006209857A - Magnetic head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamination type magnetic head which has excellent head property especially in a high frequency region, by simultaneously establishing a process of suppressing residual stress in the vicinity of an apex part and electrical short circuit (occurrence of eddy current loss) of a magnetic layer in a lamination film and a process of dissolving deviation in abutment of a core half body in the apex part, and establishing a technique of stably producing the head. <P>SOLUTION: The apex part is formed by working a second groove of a nearly semicircle using a tool capable of performing fine and highly accurate work in a first winding groove previously formed after a pair of core semicircles are integrally joined. By this method, a work load of the apex part giving great influence to the head property is suppressed to the minimum, electrical insulation of the lamination film is kept, and the eddy current loss in the high frequency region can be prevented. Further, since the deviation in abutment in the apex part of the B core semicircle can be prevented, the lamination type magnetic head having the excellent property can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated magnetic head having excellent characteristics even in a high frequency band and suitable for use in a consumer / broadcasting digital VTR or a tape streamer, and a method of manufacturing the same.

  In recent years, in the field of digital VTR and other data storage, the development of equipment that increases the recording capacity per magnetic tape and increases the transfer rate due to the rapid increase in the amount of data handled as represented by high-quality image data. Be active. Magnetic heads used in these devices are required to have high recording capability using a high saturation magnetic flux density material and excellent characteristics even in a high frequency range of 40 MHz to 100 MHz.

In contrast, a laminated magnetic head has alternating high-performance metal magnetic films such as an amorphous structure magnetic film containing Co as a main component and a fine crystal structure magnetic film containing Fe as a main component, and insulating films represented by SiO _2. The eddy current loss in the high frequency region is reduced by depositing on the surface, and particularly excellent in high frequency characteristics. Furthermore, a laminated film was developed in which the magnetic anisotropy of adjacent metal magnetic films with alternating insulation layers is alternately controlled to dramatically increase the high-frequency permeability as a whole film. A laminated magnetic head having a structure sandwiched between non-magnetic substrates having wear resistance capable of withstanding high-speed rotation of the head has been developed.

  FIG. 10A shows a configuration diagram of such a conventional laminated magnetic head, and FIG. 10B shows an enlarged view of the winding groove 6 and apex portion 7. In general, a laminated magnetic head has a core half A in which a laminated film 4 in which metal magnetic films 2 and insulating films 3 are alternately laminated as shown in FIG. B is a structure that is joined and integrated through a magnetic gap 5 made of a nonmagnetic material. In FIG. 10B, the apex portion 7 is defined by the slope portion of the winding groove 6 formed in advance on both the A and B core halves. The tip a of the apex portion 7 indicates a limit point for operating as a magnetic head, and the distance from the sliding surface to the apex portion tip a is called gap depth, which greatly affects the characteristics and life of the magnetic head. It is.

  It is known that the inner surface of the winding groove including the inclined surface has the smallest magnetic resistance as the magnetic circuit and the magnetic flux concentrates, so that the characteristics of the magnetic film in this part influence the head characteristics. For example, residual stress due to processing distortion during winding groove processing is a factor that significantly lowers the magnetic characteristics. In order to prevent the generation of eddy currents in the high-frequency region, the laminated film must have a structure in which magnetic films and insulating films are alternately laminated. Since the magnetic film is short-circuited, the high frequency characteristics may be lowered.

  As a technique for solving this, it has been proposed to use a resin-based bonding agent as a grindstone for processing a winding groove and to use a diamond grindstone with a fine particle size of about # 2500 (see, for example, Patent Document 1). ). According to this method, metal flow during winding groove processing is prevented, and the surface roughness of the processed surface is also suppressed to 0.2 micrometers or less. However, if non-magnetic substrate materials such as magnesium titanate and calcium titanate, which have excellent wear resistance, are removed with a large volume such as winding grooves using a fine grindstone, the cutting resistance will increase. Grinding wheel wobbling and meandering cause high accuracy machining. In addition, if a resin-based one that is excellent in sharpening the abrasive grains is used as the bonding agent for the grindstone, the machinability is improved. .

  Therefore, there is a method of using a grindstone that places importance on machinability for winding groove processing and removing the metal flow after processing (see, for example, Patent Document 2). According to this, the metal flow and the work-affected layer generated during the winding groove processing can be removed by chemical etching, and good magnetic properties can be ensured. In addition, processing by physical etching such as ion milling has the same effect.

  On the other hand, in the vicinity of the apex end, a leakage magnetic flux is generated that flows through the space on the opposite core half without passing through the magnetic gap. Therefore, ideally, there is no butt shift between the cores in the apex portion, and it is important for the magnetic head efficiency to equalize the magnetic resistance in the magnetic gap of both cores and reduce the leakage flux. However, in the current manufacturing method, since the A and B core halves, which are pre-rolled with groove grooves and formed with apex portions, are joined and integrated, the amount of butt displacement between both cores in the apex portion is controlled to, for example, 10 micrometers or less. It is extremely difficult to do.

As a technique for solving this problem, a method of performing a predetermined amount of removal processing on the butt misalignment portions of both cores in the apex portion after joining a pair of core halves is conceivable (see, for example, Patent Document 3). According to this method, the butt shift at the apex portion can be eliminated and the reproduction output can be improved. However, it is impossible to process non-conductive non-magnetic substrate materials and insulating layers in laminated films by electric discharge machining as the removal process method. Problems such as improvement in the surface quality of the winding groove slope portion that greatly contributes to the problem are not solved.
Japanese Patent Laid-Open No. 7-220219 JP-A-5-217112 JP 2002-304707 A

  The problems to be solved are to minimize the processing load on the apex part that greatly affects the head characteristics, maintain the electrical insulation of the laminated film to prevent eddy current loss in the high frequency region, and A, A butt shift in the apex portion of the B core half can be prevented, and a method for stably providing a high-performance laminated magnetic head has not yet been established.

  In the present invention, as a processing method for overcoming the above-mentioned problems, an apex portion is formed in a first winding groove formed in advance after the pair of core halves are joined and integrated, thereby regulating the gap depth. The main feature is that the second groove to be formed is formed using a tool that can be machined minutely and with high precision. By using this method, it is possible to minimize the processing load on the apex part that greatly affects the head characteristics and maintain the electrical insulation of the laminated film, thereby preventing eddy current loss in the high frequency region. In addition, since the butt shift at the apex portions of the A and B core halves can be eliminated, a laminated magnetic head having excellent characteristics can be obtained.

  Further, the cutting amount itself of the second groove is smaller than that of the first winding groove, and unlike the tool for forming the first winding groove, the tool for forming the second groove has a particle size of 30 micron. Since a sintered product of fine diamond particles of less than a meter is formed into a cylindrical shape by discharge truing, or diamond is electrodeposited (electroformed), it can be used as a work piece with excellent machinability and wear resistance. A mirror surface or a processed surface close thereto can be obtained without applying a load. Therefore, the apex portion can be formed with high accuracy and stability without causing deterioration of characteristics or chipping due to processing load.

  According to the present invention, it is possible to realize a laminated magnetic head suitable for consumer / broadcasting digital VTRs and tape streamers having excellent characteristics even in a high frequency band.

  According to the first aspect of the present invention, in the laminated magnetic head in which the metal magnetic film sandwiched between the nonmagnetic substrates forms the main magnetic path, the second substantially half portion provided in the first winding groove. The magnetic head is characterized in that the apex portion is formed by a circular groove and the gap depth is regulated. There is no butt shift in the apex portions of the core halves A and B, and the processing is given to the magnetic film of the apex portion. By suppressing the load and maintaining the electrical insulation of the laminated film to prevent eddy current loss in the high frequency region, a laminated magnetic head having extremely excellent characteristics is obtained.

  According to a second aspect of the present invention, the tip of the second substantially semicircular groove provided in the first winding groove is cut at least 50 micrometers or more from the first winding groove. The magnetic head according to claim 1, wherein the second substantially semicircular groove has a locality radius of 200 μm or less, and the apex portion having a large influence on magnetic characteristics is 50 in particular. In order to secure a sharp reduction in the core cross-sectional area in the vicinity of the magnetic gap of the apex portion (the effect of constricting the magnetic flux), the removal processing is performed within a range of 200 micrometers or less. It is effective.

  The invention according to claim 3 of the present invention is characterized in that the metal magnetic film has a non-crystalline structure with Co as a main component, or a fine crystal structure with Fe as a main component and a particle size of 50 nanometers or less. The magnetic head according to claim 1, wherein the magnetic head has a laminated structure with an insulating layer, and has an excellent magnetic permeability even in a high frequency region. A magnetic head having excellent high frequency characteristics can be manufactured by reliably maintaining electrical insulation between the magnetic layers in the laminated film with respect to the metal magnetic film having the above structure.

  According to a fourth aspect of the present invention, in the method of manufacturing a laminated magnetic head in which a metal magnetic film sandwiched between nonmagnetic substrates forms a main magnetic path, a pair of nonmagnetic substrates and metal magnetic films laminated alternately. Forming a winding groove on the laminated plate, and joining and integrating through a magnetic gap made of a non-magnetic material to produce a core block; processing the core block into a predetermined shape to form a chip; and A method of manufacturing a magnetic head including a step of forming a second semicircular groove in a winding groove to form an apex portion, and there is no deviation in the apex portions of both cores and the apex portion is excellent. Therefore, it is possible to stably produce a laminated magnetic head suitable for consumer / broadcasting digital VTRs and tape streamers with excellent characteristics even in the high frequency band. Rukoto can.

  The invention according to claim 5 of the present invention is a cylindrical diamond sintered body having a particle diameter of 30 micrometers or less or an electrodeposition (electroforming) tool as the tool for performing the substantially semicircular second groove processing. 5. The method of manufacturing a magnetic head according to claim 4, wherein a micro tool having excellent machinability and wear resistance is used to form a core block or a laminated film as a workpiece. The electrical insulation between the magnetic layers in the laminated film can be reliably maintained without generating cracks.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.

(Embodiment 1)
FIG. 1A is a diagram showing the configuration of the magnetic head according to the embodiment of the first invention, and FIG. 1B is an enlarged view of the apex portion 7 that regulates the winding groove 6 and the gap depth. It is a thing. In FIG. 1A, a pair of core halves sandwiching a laminated film 4 in which metal magnetic films 2 and insulating films 3 are alternately deposited on both sides by a nonmagnetic substrate 1 are interposed via a magnetic gap 5 made of a nonmagnetic material. Are joined together. In FIG. 1B, the first winding grooves 6 of the left and right core halves A and B originally had a deviation amount of δ, but the apex portion 7 is newly formed by the substantially semicircular second groove. Thus, a shape without a butt shift is realized.

In the first embodiment, an FeTaN magnetic film is used as the metal magnetic film, an Al ₂ O ₃ film is used as the insulating film, a magnesium titanate substrate is used as the nonmagnetic substrate, the FeTaN magnetic film is 2.3 micrometers, and the Al ₂ O ₃ film is 0.3. The laminated film of about 9.6 micrometers was produced by setting it as 1 micrometer and laminating | stacking four layers alternately. The first winding groove 6 has a shape in which the processing width in the width direction of the core is 200 micrometers, the processing width in the height direction is 300 micrometers, and the local radius of the second substantially semicircular groove is about 150 micrometers. The amount of cut from the winding groove 6 is about 100 micrometers. At this time, the processed surface roughness of the laminated film in the second substantially semicircular groove was 0.1 μm or less. In this way, particularly in the vicinity of the tip of the apex 7, the processing load applied to the magnetic film significantly affects the head characteristics. Therefore, the second substantially semicircular groove is formed in the first winding as in the present embodiment. It is appropriate to form at least 50 micrometers or more from the window so that the processing strain does not remain near the tip of the apex portion 7. Further, if the local radius of the second substantially semicircular groove is increased, the change in the core cross-sectional area in the direction of the magnetic gap in the apex portion 7 becomes gradual, so that a sharp magnetic flux cannot be narrowed down. Therefore, it is appropriate that the locality radius of the second substantially semicircular groove is 200 micrometers or less. Compared with the conventional laminated magnetic head in which the amount of butt shift at the apex portion is about 50 micrometers, this laminated magnetic head has a relative value of 1.5 dB or more over the entire frequency band, particularly about 2 at 60 MHz. It was found to be improved by 5 dB. Therefore, it was possible to realize a laminated magnetic head suitable for consumer / broadcasting digital VTRs and tape streamers having excellent characteristics even in a high frequency band. In this embodiment, an FeTaN magnetic film is used as the metal magnetic film 2, but this magnetic film has a small apparent crystal magnetic anisotropy constant and excellent magnetic characteristics especially when the crystal grain size is 50 micrometers or less. Is. It was also confirmed that the same effect can be obtained with a metal magnetic film having an amorphous structure containing Co as a main component.

In the first embodiment, Al ₂ O ₃ is used as the insulating film, but the same effect can be obtained by using other insulating materials such as SiO ₂ or high-resistance oxide magnetic materials such as FeMg. Further, although the magnesium titanate substrate is used as the nonmagnetic substrate, the same effect can be obtained with a nonmagnetic substrate such as calcium titanate or nonmagnetic single crystal ferrite. Further, the film thickness and the number of stacked layers of the metal magnetic film and the insulating film shown in the first embodiment are not limited to this.

(Embodiment 2)
2 to 7 show the manufacturing process of the laminated magnetic head according to the embodiment of the second invention. First, as shown in FIG. 2, a laminated block 9 is produced by adhering 16 nonmagnetic substrates 8 on which a laminated film is formed by sputtering through a bonding glass layer, and a predetermined azimuth is formed using a wire saw. The attached laminated plate 10 was cut out. Next, as shown in FIG. 3, the first winding groove 6 was formed on the gap facing surface of both the laminated plates by grinding.

  Thereafter, a step of mirror polishing the gap facing surfaces of the pair of laminated plates to a predetermined surface roughness to form a nonmagnetic gap material or adhesive glass, and a step of performing a heat treatment while holding the pair of laminated plates under pressure Then, a gap-bonded joining plate 11 shown in FIG. 4 was produced. After cutting out the core block 12 shown in FIG. 6 from the bonding plate 11, predetermined outer shape processing and chip forming processing were performed, and a magnetic head chip as shown in FIG. 7 was manufactured.

  Next, a fine diamond tool 20 as shown in FIG. 8 (a) is inserted into the first winding groove 6 as shown in FIG. 8 (b) and moved in a direction to regulate the gap depth for removal processing. The apex part 7 was formed. The tool 20 used at this time has a diameter of about 0.1 mm and a length of about 0.5 mm. This tool is originally a diamond sintered body with a particle size of about 30 micrometers, but as a result of discharge truing it, the diamond particle size of the tool surface layer is about 0.5 micrometers (equivalent to # 10000). Is confirmed. Thus, by carrying out the discharge truing of the fine particle diamond having a particle size of 30 micrometers or less, the machined surface roughness is extremely small, and a micro tool suitable for the second substantially circular groove processing can be produced. At this time, the processing speed was 5 micrometers / second, and the tool rotation speed was 50000 rotations / minute. In this way, the laminated magnetic head shown in FIG. 9 could be manufactured. It was confirmed that this laminated magnetic head has no butt shift between the A and B core halves in the apex portion 7 and has excellent characteristics even in the high frequency band.

  In the second embodiment, the first winding groove 6 is formed by grinding in the initial state of the plate. However, the present invention is not limited to this, and the second substantially semicircular groove is formed after the magnetic head chip is manufactured. This can also be realized by drilling using the same tool.

  As described above, the magnetic head and the manufacturing method thereof according to the present invention realize high-precision and high-quality processing of the apex portion by using a diamond micro tool, and use an oxide magnetic body as a magnetic core. A magnetic head, a magnetic head having a structure in which a metal magnetic film formed on a gap surface of a nonmagnetic core forms a magnetic path, and a metal in-gap magnetic head having a structure in which a metal magnetic film is disposed only in the vicinity of a magnetic gap of an oxide magnetic body Other bulk type magnetic heads can also be used for applications that require precise apex forming.

1 is a schematic diagram showing a laminated magnetic head according to a first embodiment of the present invention. Schematic showing the manufacturing process of the laminated magnetic head according to the second embodiment of the present invention. Schematic showing the manufacturing process of the laminated magnetic head according to the second embodiment of the present invention. Schematic showing the manufacturing process of the laminated magnetic head according to the second embodiment of the present invention. Schematic showing the manufacturing process of the laminated magnetic head according to the second embodiment of the present invention. Schematic showing the manufacturing process of the laminated magnetic head according to the second embodiment of the present invention. Schematic showing the manufacturing process of the laminated magnetic head according to the second embodiment of the present invention. Schematic showing diamond tool and manufacturing process according to Embodiment 2 of the present invention Schematic showing a laminated magnetic head according to a second embodiment of the present invention. Schematic diagram showing a conventional laminated magnetic head

Explanation of symbols

A, B Core half a Apex tip 1 Nonmagnetic substrate 2 Metal magnetic film 3 Insulating film 4 Laminated film 5 Magnetic gap 6 Winding groove 7 Apex 8 Nonmagnetic substrate 9 Laminated block 10 Laminated plate 11 Bonded plate 12 Core block 20 diamond tools

Claims (5)

In a laminated magnetic head in which a metal magnetic film sandwiched between nonmagnetic substrates forms a main magnetic path, an apex portion is formed by a second substantially semicircular groove formed in a first winding groove, and a gap depth is formed. Is a magnetic head that is regulated. The tip of the second substantially semicircular groove provided in the first winding groove is cut by at least 50 micrometers or more from the first winding groove, and the second substantially semicircular groove 2. The magnetic head according to claim 1, wherein a locality radius of the magnetic head is 200 micrometers or less. The metal magnetic film is either a metal magnetic film having an amorphous structure containing Co as a main component, or a metal magnetic film having a fine crystal structure containing Fe as a main component and a particle size of 50 nanometers or less, and is insulated. 3. The magnetic head according to claim 1, wherein the magnetic head has a laminated structure with a layer. In the method of manufacturing a laminated magnetic head in which a metal magnetic film sandwiched between nonmagnetic substrates forms a main magnetic path, after forming winding grooves on a pair of laminated plates in which nonmagnetic substrates and metal magnetic films are alternately laminated, A step of producing a core block by joining and integrating via a magnetic gap made of a non-magnetic material, a step of processing the core block into a predetermined shape and forming a chip, and a second semi-circular shape in the winding groove And a step of forming an apex portion by performing groove processing. 5. A cylindrical diamond sintered body having a particle size of 30 micrometers or less or an electrodeposition (electroforming) tool is used as the substantially semicircular second groove processing tool. Method of manufacturing the magnetic head of the present invention.

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