THIN-FILM MAGNETIC HEAD AND METHOD OF PRODUCING THE SAME

Abstract: A thin-film head for magnetic recording and reproduction having magnetic poles constituted of two thin films and a method of producing the same. It aims at eliminating waveform distortion caused by false pulses and forming a magnetic layer that constitutes the magnetic pole without resort to machining. A pair of magnetic poles (1) and (2) of a thin-film head are formed out of parallel with each other, the head is permitted to run parallel to film surface of one magnetic pole (2), the other magnetic pole (1) is formed to have a film thickness sufficiently shorter than the recording wavelength, whereby the recording and reproduction are carried out without distortion in the waveform and crosstalk. Between the pair of magnetic poles, the magnetic pole that is not in parallel with the plane in parallel with the direction of head running is laminated maintaining a thickness that corresponds to the track width and is then shaped into a film having a width of 0.05 mu m to 1 mu m by photolitography and etching.

Description: TECHNICAL FIELD The present invention relates to a magnetic head and a method for manufacturing thereof. More particularly, the invention pertains to a thin film magnetic head in which two thin films of first and second magnetic layers constitute a pair of magnetic poles, and a method for the manufacture of such a thin film magnetic head. TECHNICAL TERMS In this specification, a term "opposed surface area" is intended to mean a surface area of the magnetic head which makes direct contact with a magnetic recording medium when the magnetic head is of the type that makes contact therewith for recording and reproducing, and a surface area of the magnetic head which is held out of contact with the magnetic recording medium but at a distance therefrom sufficient for recording and reproducing when the magnetic head is of the type that performs recording and reproducing without making contact with the magnetic recording medium. A term "head running direction" is intended to mean the direction in which the magnetic head travels relative to the magnetic recording medium in both cases where the magnetic head runs on the magnetic recording medium and where the latter runs on the former. BACKGROUND ART In JP 61-172206 there is disclosed a vertical recording head having a main pole which extends across a recording track in a plane at right angles to the running direction and an auxiliary pole situated to one side of the main pole outside the track with which the main pole co-operates. In JP 59-218616 there is disclosed a vertical recording head having a main pole formed of a thin film layer extending perpendicular to the face of the recording medium and an auxiliary pole formed by a layer which extends parallel to the face of the recording medium. It is known to produce a thin film magnetic head for longitudinal recording with two poles situated along the running direction as shown in Figs. 12 and 13, by laminating a non-magnetic substrate 3 a second magnetic material layer 2, a gap material 8, coil conductor layers 4, and a first magnetic material layer 1 which constitutes a pair of magnetic poles with the second magnetic material layer 2 in this order. Usually, in this kind of thin film magnetic head, the first magnetic material layer 1, the gap material 8, the coil conductor layer 4, and the second magnetic material layer 2 are all provided in planes parallel to the surface of the non-magnetic substrate (3), and the head is disposed so that it runs on a magnetic recording medium (not shown) in a direction perpendicular to the above planes for recording and reproducing. Such a thin film magnetic head inevitably suffers from the generation of a waveform distortion or false pulse which is caused by the thicknesses of first and second magnetic material layers 1 and 2, as shown in a solitary reproduced waveform diagram of Fig. 14. The waveform distortion occurs when a false gap parallel to the recording and reproducing gap of the magnetic head is formed in its surface area opposed to the magnetic recording medium 10. In the thin film magnetic head, in particular, since the thicknesses of the pair of magnetic poles formed by the first and second magnetic material layers 1 and 2 are approximate to the wavelength for recording, the false pulse by the false gap distorts the signal waveform reproduced from the true gap, impairing the reproduced signal quality. A method that has been proposed for reducing the waveform distortion is disclosed in Japanese Patent Laid-Open Gazette No. 205508/87, for example. According to this method, the thickness of the first magnetic material layer 1 is varied widthwise of the magnetic track on the recording medium so that the bottom 9 of the first magnetic material layer 1 on the opposite side from the gap material 8 is inclined thereto, as shown in Fig. 15. The magnetic head of this structure is capable of suppressing the generation of the false signal by the false gap and hence lessening its influence but is incapable of completely removing the waveform distortion. Further, the manufacture of such a magnetic head involves many machining steps such as the formation of a groove having a bottom inclined by an angle ϑ in the non-magnetic substrate 3, sputtering of the first magnetic material layer 1 on the substrate 3, and subsequent lapping of its surface-this is not preferable as the thin film magnetic head manufacturing process. In addition, since it is difficult to improve the surface roughness of the bottom surface of the groove inclined by the angle ϑ, there is a fear of providing poor magnetic characteristics of the first magnetic material layer 1. Another prior art method proposed as a solution to the above problem is shown in Fig. 16, in which first and second magnetic material layers 1 and 2 on the non-magnetic substrate 3 are spaced apart in the direction A widthwise of the magnetic track (Japanese Patent Laid-Open Gazette No. 95713/87). This magnetic head structure is capable of eliminating the waveform distortion but encounters a problem of crosstalk from adjoining other tracks and overwrite thereinto which are caused by edge portions E of the second magnetic material layer 2 in the opposed surface area. DISCLOSURE OF THE INVENTION It is therefore an object of the present invention to provide a thin film magnetic head which is free from the waveform distortion by the false pulse. Another object of the present invention is to provide a method for manufacturing of a thin film magnetic head which does not involve machining and lapping for the formation of the first magnetic material layer. According to an aspect of the present invention, the thin film magnetic head has a non-magnetic layer, the coil conductor layers and a second magnetic material layer in planes parallel to the head running direction and a first magnetic material layer having a portion in the opposed surface area which extends in a plane unparallel i.e. nonparallel to the head running direction, as laid down in claims 1 and 2 With such a structure, the second magnetic material layer parallel to the head running direction has neither of a gap and a false gap in the opposed surface area, and the first magnetic material layer unparallel to the head running direction in the opposed surface area can be formed to a sufficiently small thickness in the head running direction as compared with the recording wavelength. Consequently, it is possible to prevent the generation of the waveform distortion by a false pulse, reduce a peak shift amount in digital recording and a harmonic distortion and a frequency characteristic fluctuation (a contour effect) in analog recording, and eliminate crosstalk from adjoining tracks and overwrite thereinto. According to another aspect of the present invention, a thin film magnetic head as laid down in claim 8 is provided for magnetic layers along the head running direction, a first magnetic material layer formed in the plane of the second-mentioned non-magnetic layer unparallel to the head running direction and connected to the second magnetic layer, and coil conductor layers formed around the connecting portion of the first and the second magnetic material layers. According to a further aspect of the present invention, a thin film magnetic head according to claim 9 is envisaged. A method for manufacturing of the thin film magnetic head of claim 9 is laid down in claim 10. Consequently, the first magnetic material layer is formed very accurately to a width corresponding to the track width by film thickness control and to a desired thickness in the opposed surface area in the head running direction by etching or ion beam milling. A method for manufacture of a thin film head according to Claim 1 is laid down in Claim 12. Thus, the manufacturing method of the present invention permits the manufacture of the thin film magnetic head of the invention without involving machining and lapping in the step of forming the first magnetic material layer, and hence is excellent in productivity and highly economical. Moreover, the method of the present invention provides a thin film magnetic head which is free from the influences of an increase in strain of the substrate, deterioration of the magnetic film and an increase in the roughness of the substrate surface which are caused by machining and lapping or grinding, that is, a thin film magnetic head which does not cause a waveform distortion nor generates a false pulse. By applying the present invention to a multi-channel thin film magnetic head, in particular, it is possible to reduce crosstalk from the adjoining tracks, obtaining excellent recording and reproducing characteristics. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing, in section, the principal part of an embodiment of the thin film magnetic head according to the present invention along the line I-I in Fig. 2; Fig. 2 is a plan view of the head as viewed from the side of its sliding surface; Figs. 3(A) to (F) illustrate in sequence one example of the steps employed in the formation of a first magnetic material layer of the head depicted in Fig. 1; Fig. 4 is a perspective view showing, in section, the principal part of another embodiment of the present invention along the line IV-IV in Fig. 5; Fig. 5 is a plan view of the head as viewed from the side of its sliding surface; Fig. 6 is a perspective view showing, in section, the principal part of still another embodiment of the present invention along the line VI-VI in Fig. 7; Fig. 7 is a plan view of the head s viewed from the side of its sliding surface; Fig. 8 is a perspective view showing, in section, the principal part of further another embodiment of the present invention along the line VIII-VIII in Fig. 9; Fig. 9 is a plan view of the head as viewed from the side of its sliding surface; Fig. 10 is a diagram showing the process of reproduction by the thin film magnetic head of the present invention and a solitary reproduced waveform; Figs. 11 (A) to (D) illustrate in sequence of one example of the steps involved in the manufacture of the thin film magnetic head according to the present invention; Fig. 12 is a perspective view showing, in section, the principal part of an example of a conventional thin film magnetic head; Fig. 13 is a plane view of the conventional head as viewed from the side of its sliding surface; Fig. 14 is a diagram showing the process of reproduction by the conventional thin film magnetic head and a solitary reproduced waveform; Fig. 15 is a plan view of another conventional thin film magnetic head as viewed from the side of its sliding surface; and Fig. 16 is a perspective view showing still another conventional head. BEST MODE FOR CARRYING OUT THE INVENTION With reference to the drawings, embodiments of the present invention will hereinafter be described in detail. In the embodiments the parts corresponding to those in the conventional thin magnetic heads described previously are identified by the same reference numerals and no detailed description will be given of them. Figs. 1 and 2 illustrate an embodiment of the thin film magnetic head of the present invention. Reference numeral 1 indicates a first magnetic material layer, 2 a second magnetic material layer, 3 a non-magnetic substrate, 4 coil conductor layers, 5 a head protective film formed of an non-magnetic or magnetic material, 6 a coil insulating layer, and 7 a fusing or adhesive agent. In this thin film magnetic head the coil insulating layer 6, the coil conductor layers 4, the second magnetic material layer 2, and the head protective film 5 are sequentially laminated on the non-magnetic substrate 3 in parallel to the head running direction B and the first magnetic material layer 1 is formed on the non-magnetic substrate 3 in a direction unparallel to the head running direction. The first and second magnetic material layers 1 and 2 thus provided unparallel to each other constitute a pair of magnetic poles, which are spaced apart by the coil insulating layer 6 formed of a non-magnetic material. The second magnetic material layer 2 is formed to be gradually spaced apart from the recording medium so that it has no edge in the head running direction B. While in this embodiment the first and second magnetic material layers 1 and 2 are formed on the. non-magnetic substrate 3 so that they are unparallel to each other, the invention is not limited specifically to the above structure. The essential thing is to form the second magnetic material layer 2 in a certain plane parallel to the head running direction B and the first magnetic material layer 1 in a certain plane unparallel to the second magnetic material layer 2. The first and second magnetic material layers 1 and 2 are each formed by a soft magnetic film such as an amorphous film of the cobalt series (a Co-Zr-Nb amorphous film, for instance) or sendust film; the non-magnetic substrate 3 is formed of crystallized glass or ceramics of the alumina series, for example; the coil conductor layers 4 are formed by aluminum, copper or similar films; and the head protective film 5 and the coil insulating layer 6 are formed of silicon dioxide or a photoresist material, for instance. In this specification, what is intended to mean by "the first magnetic material layer 1 is unparallel" is that either plane in which the first magnetic material layer 1 is in contact with the non-magnetic substrate 3 is not parallel to the head running direction B, i.e. to the second magnetic material layer 2 in at least the opposed surface area. By providing the second magnetic material layer 2 in parallel to the head running direction B and forming it in such a manner as not to have an edge in the head running direction B in the opposed surface area, the formation of a false gap in the head running direction B which would otherwise be caused by the second magnetic material layer 2 is avoided, and consequently, the generation of a false pulse is suppressed. On the other hand, the thickness t of the first magnetic material layer 1 in the head running direction B can be made sufficiently smaller than the recording wavelength, for example, 0.05 to 1.0 µm. Fig. 10 shows a solitary reproduced waveform by the thin film magnetic head of the present invention and its reproducing process. It will be seen from Fig. 10 that no waveform distortion occurs in principle. Figs. 3(A) through (F) illustrates a sequence of steps involved in the formation of the first magnetic material layer 1 of the thin film magnetic head depicted in Fig. 1. At first, the first magnetic material layer 1 is formed to a thickness sufficiently smaller than the recording wavelength, for example about 0.05 to 1.0 µm, on the non-magnetic substrate 3 by vapor deposition, electrodeposition, or sputtering [see Fig. 3(A)]. The first magnetic material layer 1 thus formed is subjected to patterning as by photolithography so that it is selectively etched into a comb-like form, each tooth having a width W corresponding to the track width [see Fig. 3(B)]. Then, the comb-shaped pattern is cut into individual chips as indicated by the one-dot chain lines [see Fig. 3(C)]. In this instance, the angle ϑ₁ between the horizontal top surface of the substrate 3 and the cut end face can be set to any desired values except 0° and 180°. Incidentally, in order to perform crosstalk-free signal reproduction by two heads without providing a guard band between two adjacent tracks on a magnetic medium, it is desirable, in general, that an azimuth angle of 10° to 45° be provided with respect to the gap of one of the two heads. Accordingly, the angle ϑ₁ may preferably be set in the range of from 45° to 135°, taking such an azimuth angle into consideration. Next, the individual chips, each composed of the first magnetic material layer 1 and the non-magnetic substrate 3, are each welded or joined to the non-magnetic substrate 3 of another chip by the welding or adhesive agent 7 with the first magnetic material layer 1 sandwiched therebetween and the assembly thus obtained is welded or joined to still another non-magnetic substrate 3 [see Fig. 3(D)]. Thereafter, the top surface of the substrate assembly holding the first magnetic layers 1 between the non-magnetic substrates 3 is ground, partly exposing the first magnetic material layers 1 [see Fig. 3(E)]. Then, the grounded surface is cleaned [see Fig. 3(F)]. The coil conductor layers 4 are disposed around and magnetically coupled with the exposed portion la of each first magnetic material layer 1 of such a compound substrate assembly composed of the non-magnetic substrates 3 and the first magnetic material layers 1. Then the second magnetic material layer 2 is formed which constitutes one of the pair of magnetic poles, and the head protective film 5 is formed. In this way, the thin film magnetic head is produced. After the formation of each head, its surface area head which is to be opposed to the magnetic recording medium is rounded by polishing so that the second magnetic material layer 2 has no edges in the head running direction B. Fig. 4 and 5 illustrate another embodiment of the thin film magnetic head of the present invention, in which the space of the first and second magnetic material layers 1 and 2 in the Fig. 1 embodiment is reduced. The thickness of the coil insulating layer 6 is reduced in the opposed surface area and the second magnetic material layer 2 is formed near the non-magnetic substrate 3 accordingly, thereby decreasing the space of the first and second magnetic material layers 1 and 2. Figs. 6 and 7 illustrate another embodiment of the thin film magnetic head of the present invention. Unlike in the above-mentioned embodiments the second magnetic material layer 2 is formed on the non-magnetic substrate 3 and then the coil conductor layers 4, the coil insulating layer 6, the first magnetic material layer 1 and the head protective film 5 are laminated in this order on the second magnetic material layer 2. The thickness t₂ of the first magnetic material layer 1 in the direction of lamination is selected equal to the track width. In this instance, the first magnetic material layer 1 is formed so that its thickness t in the head running direction B is 0.05 to 1.0 µm in the opposed surface area but gradually increases as it extends backwardly thereof. Further, the film of the first magnetic material layer 1, which has the thickness t in the opposed surface area, is formed so that it extends in a direction at an angle ϑ₂ of any desired values except 0° and 180°, for example, 90° in this embodiment, with respect to the second magnetic material layer 2. Figs. 8 and 9 illustrate still another embodiment of the thin film magnetic head of the present invention, in which another set of coil conductor layers 4a and another second magnetic material layer 2a are laminated on the first magnetic material layer 1 of the magnetic head shown in Figs. 6 and 7, and finally non-magnetic substrate 3a is joined to them. This embodiment is intended to lessen the influence of an external electromagnetic disturbance by differential coupling of the coil conductor layers 4 and 4a. In this case, it is necessary that the additional second magnetic material layer 2a and the first magnetic material layer 1 be coupled to each other centrally of the coil conductor layers 4. The manufacturing process of this head from the formation of the second magnetic material layer 2 to the formation of the first magnetic material layer 1 is the same as in the case of the head depicted in Figs. 6 and 7. Now, a description will be given of a method of the magnetic head of the type shown in Figs. 6 through 9. At first, the second magnetic material layer 2 is formed on the non-magnetic substrate 3, the coil conductor layers 4 are formed on the second magnetic material layer 2, and the coil insulating layer 6 is formed on the coil conductor layers 4, followed by flattening the surface of the coil insulating layer 6. Then the first magnetic material layer 1 is formed, on the substrate assembly, to the thickness t₂ corresponding to a desired track width through vapor deposition, electrodeposition, or sputtering [see Fig. 11(A)]. Next, photoresist 21 is coated all over the first magnetic material layer 1 and is patterned as by photolithography into such a form in which its line width in the opposed surface area, that is, the width t in the head running direction is 0.05 to 1.0 µm and gradually increases as it extends backwardly of the opposed surface area [see Fig. 11(B)]. This patterning is anisotropic one by dry or wet etching or ion beam milling. Reference numeral 22 indicates ion beams. Although in this example the direction of etching, i.e. the angle ϑ₂ of the first magnetic material layer 1 to the second magnetic material layer 2 is shown to be 90°, it may take any desired values except 0° and 180°. The above etching is followed by the removal of the remaining photoresist 21 [see Fig. 11(C)] and then by the formation of the head protective film 5 [see Fig. 11(D)]. As will be seen from this process diagram, the thickness t₂ of the first magnetic material layer 1 in the direction of lamination corresponding to the track width can be made highly accurate under thickness control even if the track width is very small, because the first magnetic material layer 1 is formed by vapor deposition, electrodeposition, or sputtering. The manufacturing process of the present invention exemplified in Fig. 11 permits easy fabrication of the thin film magnetic head of Fig. 9 which is robust against an external electromagnetic disturbance. By repeating the manufacturing process it is possible to manufacture an in-line multichannel thin film magnetic head of little crosstalk. The above embodiments are preferred embodiments of the present invention, it is intended as merely illustrative of the invention and should not be construed as limiting the invention specifically thereto, and many modifications and variations may be effected without departing from the scope of the novel concepts of the invention. For instance, the coil conductor layers 4 and 4a may also be formed by reluctance elements or elements utilizing ferromagnetic resonance. Further, it is a matter of course that a multichannel head can be fabricated by repeating one of the manufacturing processes of the heads of these embodiments. The reluctance elements and elements utilizing ferromagnetic resonance (which detect, as an output signal of a resonance circuit, a change in the high frequency permeability of a soft magnetic thin film such as an Ni-Fe film) may be disposed between the first and second magnetic material layers 1 and 2, or the first magnetic material layer 1 itself may also be replaced with the reluctance element and the element utilizing ferromagnetic resonance. Moreover, in the heads shown in Figs. 7, 8 and 9 the non-magnetic substrate 3 may also be replaced with a magnetic substrate. In this instance, since the magnetic substrate serves as the second magnetic material layer and constitutes a pair of magnetic poles in cooperation with the first magnetic material layer, the second magnetic material layer 2 can be left out. Besides, the first and second magnetic material layers land 2 for improving the high frequency characteristics may each be formed by a laminated film including a non-magnetic intermediate film.

Claims: A magnetic head for use in a running direction with respect to a magnetic recording medium, said magnetic head including a main magnetic pole which extends across a recording track and a second pole situated to one side of the main pole outside the track with which the main pole is to co-operate, the main and second poles being located in an opposed surface area of said magnetic head which is to be opposed to said magnetic recording medium, characterised in that the magnetic head is a thin film head and that the main magnetic pole is defined by a first magnetic material layer (1) and the second magnetic pole is defined by a second magnetic material layer (2), the head further comprising a non-magnetic substrate (3) and a magneto-electrical transducer layer (4), said non-magnetic substrate (3), transducer layer (4) and second magnetic material layer (2) being formed in a parallel relation with said running direction, whereas said first magnetic material layer (1) is formed at least in said opposed surface area of said magnetic head with an end portion extending in a nonparallel relation with said running direction, the end portion being embedded in a further non-magnetic layer (3 or 5) wherein the entire first magnetic layer lies in a non-parallel relation with said running direction and said end portion is defined by an edge of the layer. A magnetic head for use in a running direction with respect to a magnetic recording medium, said magnetic head including a main magnetic pole which extends across a recording track and a second pole situated to one side of the main pole outside the track with which the main pole is to co-operate, the main and second poles being located in an opposed surface area of said magnetic head which is to be opposed to said magnetic recording medium, characterised in that the magnetic head is a thin film head and that the main magnetic pole is defined by a first magnetic material layer (1) and the second magnetic pole is defined by a second magnetic material layer (2), the head further comprising a non-magnetic substrate (3) and a magneto-electrical transducer layer (4), said non-magnetic substrate (3), transducer layer (4) and second magnetic material layer (2) being formed in a parallel relation with said running direction, whereas said first magnetic material layer (1) is formed at least in said opposed surface area of said magnetic head with an end portion extending in a nonparallel relation with said running direction, the end portion being embedded in a further non-magnetic layer (3 or 5) wherein the first magnetic material layer is formed in a parallel relation with said running direction but is shaped to define the end portion in said opposed surface area so that said end portion is non-parallel to the running direction. A magnetic head according to claim 1 or 2, characterised in that said second magnetic material layer is further formed to be opposed to said magnetic recording medium at said opposed surface area, and formed to extend progressively away from said recording medium so that the second magnetic material layer has no edge in the head running direction in said opposed surface area of the head. A magnetic head according to claim 1, 2 or 3 when dependent on claim 1, characterised in that in said opposed surface area the thickness of the first magnetic material layer in the head running direction is in the range of between 0.05 to 1.0 µm. A magnetic head according to any preceding claim wherein the transducer layer comprises a coil conductor layer. A magnetic head according to any of claims 1 to 4 wherein the transducer layer comprises a reluctance element. A magnetic head according to any of claims 1 to 4 wherein the transducer layer comprises a ferromagnetic resonance element. A thin film magnetic head comprising two non-magnetic layers (3,3a) formed in parallel relation along a direction of running of the head relative to a magnetic recording medium; another non-magnetic layer (5) formed between the two non-magnetic layers along the head running direction; a pair of second magnetic material layers (2,2a) formed between said another non-magnetic layer and each of the two non-magnetic layers along the head running direction; a first magnetic material layer (1) formed on part of said another non-magnetic layer along the head running direction and having an end portion in an opposed area of the head that is to be opposed to the magnetic recording medium which is non-parallel to the head running direction, the first magnetic material layer being connected to the second magnetic material layers, and magneto-electrical transducer layers (6,6a) formed around the connecting portions of the first and second magnetic material layers, said end portion of the first magnetic layer defining a main pole that extends across the recording track, and cooperating with auxiliary poles defined by the second magnetic layers, which are situated to the sides of the main pole outside the track with which the main pole is to cooperate. A thin film magnetic head comprising: a non-magnetic substrate (3) disposed along a direction of running of the head relative to a magnetic recording medium; a second magnetic material layer (2) formed on the substrate along the head running direction; a first magnetic material layer (1) having an exposed end which is non-parallel to the head running direction at least in an opposed surface area of said magnetic head which is to be opposed to said magnetic recording medium and a connecting portion where the first magnetic material layer is partly connected to the second magnetic material layer; a magneto-electrical transducer layer (4) provided between the first and second magnetic material layers around the connecting portion thereof; and a non-magnetic head protective layer (5) surrounding the first magnetic material layer for protecting the first magnetic material layer. A method for manufacture of a thin film magnetic head in which a second magnetic material layer (2), a gap material or non-magnetic oxide layer, magneto-electrical transducer layers (4), a coil insulating layer (6), and a first magnetic material layer (1) constituting a pair of magnetic poles in cooperation of said second magnetic material layer are laminated in this order on a substrate (3), the thin film magnetic head being relatively movable in a direction parallel to the surfaces of these layers, characterised in that the first magnetic material layer (1) is formed to a thickness corresponding to a desired track width and is shaped by photolithograph, etching, or ion beam milling to define a portion in an opposed surface area of the head which is to be opposed to a magnetic recording medium, the portion having a dimension equal to the track width in a plane non-parallel with the running direction and a dimension smaller than a recording wavelength in a plane parallel to the running direction. A thin film magnetic head manufacturing method according to claim 10, characterised in that the first magnetic material layer is formed so that in the opposed surface area of the head said dimension of said portion in said plane parallel to the running direction is 0.05 to 1.0 µm and gradually increases in the running direction as it extends away from the opposed surface area of the head. A method of manufacture of a thin film magnetic head according to claim 1, the method comprising forming the first magnetic layer (1) on a non-magnetic substrate (3), patterning the first magnetic layer (1) into comb-like form having a series of teeth, cutting the non-magnetic substrate (3) and first magnetic layer (1) between each tooth of the comb-like form to define a chip, joining or welding the chips to one another with the first magnetic layer (1) sandwiched between adjacent chips, to form a substrate assembly, grinding a surface of the substrate assembly to partly expose the first magnetic layer (1) and define exposed portions (1a), disposing magnetically coupled and conductor layers (4) around each exposed portion (1a), forming a second magnetic material layer (2) on the conductor layers (4) and then forming a protective film (5) on the second magnetic material layer (2).

Inventors: ARUGA FUSAYOSHI, NUMAZAWA JUNJI NIPPON HOSO KYO, ARUGA, FUSAYOSHI, NUMAZAWA, JUNJI NIPPON HOSO KYOKAI HOSO
Applicants: JAPAN BROADCASTING CORP, SANKYO SEIKI SEISAKUSHO KK, KABUSHIKI KAISHA SANKYO SEIKI SEISAKUSHO, NIPPON HOSO KYOKAI
Application year: 1988
Main classification: G11B5
IPC codes: G11B5