Thin-film magnetic transducer with a multitude of magnetic flux interactions

• US 5,331,496 A
• Filed: 02/14/1992
• Issued: 07/19/1994
• Est. Priority Date: 02/14/1992
• Status: Expired due to Fees

• Current Assignee: Matsushita-Kotobuki Electronics Industries, Ltd.
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Batra, Sharat, Wu, Andrew L.
• Primary Examiner(s): Heinz, A. J.
• Assistant Examiner(s): DITMYER, PAUL JOSEPH
• Application Number:
  US07/837,358
• Time in Patent Office: 886 Days
• Field of Search: 360/126, 360/125, 360/123, 428/336, 29/603
• US Class Current: 360/125.33
• CPC Class Codes: G11B 5/3113 for improving the magnetic domain structure or avoiding the formation or displacement of undesirable magnetic domains
• CPC Class Codes: G11B 5/313 Disposition of layers
• CPC Class Codes: G11B 5/3163 Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
• CPC Class Codes: Y10T 29/49034 Treating to affect magnetic properties
• CPC Class Codes: Y10T 29/49064 by coating
• CPC Class Codes: Y10T 29/49066 Preformed winding

Abstract

A thin film magnetic head, and process for making the same, features a thin film magnetic transducer formed from multiple layers of film and having a magnetic yoke interacting with an electrical coil. The yoke has multiple magnetic flux circuits, deposited on multiple layers of film, encircling the center of the transducer and connected together by proximal and distal vias. A coil has multiple turns intertwined with the yoke, passing between the distal and proximal vias so that the distal vias are exterior to the coil and the proximal Vias are interior to the coil, to provide at least four magnetic flux interactions between the coil and the yoke. In preferred embodiments at least one layer of the film is deposited with at least two pole pieces having different easy axis orientations. In other preferred embodiments at least one distal via is configured as an elongated "flux strap" for conducting magnetic flux along the length of the via in a direction oblique to the easy axis of either pole piece coupled together by the magnetic flux strap.

Claims

1. A thin film magnetic transducer formed of a film having a plurality of layers and comprising:

a yoke having a plurality of magnetic flux circuits disposed about the center of the transducer such that there exists for each magnetic flux circuit two terminal end portions for coupling magnetic flux into and out of each magnetic flux circuit, each magnetic flux circuit having a first pole piece disposed in one layer of the film coupled at a corresponding distal via to a second pole piece disposed in another layer of the film, said distal via traversing the layers of the film and disposed on a portion of the magnetic flux circuit distal to the terminal end portions relative to the center of the transducer, each terminal end portion of each magnetic flux circuit being magnetically coupled to a corresponding terminal end portion of an adjacent magnetic flux circuit through a corresponding proximal via traversing the layers of the film and disposed proximal to the center of the transducer, each pole piece having an easy axis of magnetization oriented substantially perpendicular to a flux conduction path therein lying among a line of sight between the centers of the corresponding distal and proximal vias at opposite ends thereof, and wherein the line of sight in the first pole piece and the line of sight in the second pole piece intersect at the distal via coupling the first and second pole pieces, said magnetic flux circuits being disposed such that there are at least two pole pieces in each of said layers having non-parallel easy axes;

a first tip pole piece having a pole tip and disposed in said one layer of the film, said first tip pole piece having one end adapted for positioning adjacent to a magnetic medium for coupling magnetic flux between the medium and the yoke, and having its other end magnetically coupled to a corresponding terminal end portion of an adjacent magnetic flux circuit through a corresponding proximal via;

a second tip pole piece having a pole tip and disposed in said other layer of the film, said second tip pole piece having one end adapted for positioning adjacent to the magnetic medium for coupling magnetic flux between the medium and the yoke, and having its other end magnetically coupled to a corresponding terminal end portion of an adjacent magnetic flux circuit through a corresponding proximal via; and

a coil having a plurality of turns intertwined with the yoke and passing between the distal and proximal vias, so that the distal vias are exterior to the coil and the proximal vias are interior to the coil, to provide at least four magnetic flux interactions between the coil and the yoke.

2. The thin film magnetic head of claim 1 wherein a plurality of the pole pieces have an easy axis forming an oblique angle of substantially 15°

with the longitudinal axis f the transducer.

3. The thin film magnetic head of claim 1 wherein a plurality of the pole pieces have an easy axis forming an oblique angle of substantially 15°

with the lateral axis of the transducer.

4. The thin film magnetic head of claim 1 wherein

a plurality of the pole pieces have an easy axis forming an oblique angle of substantially 15°

with the longitudinal axis of the transducer, and

another plurality of the pole pieces have an easy axis forming an oblique angle of substantially 15°

with the lateral axis of the transducer.

5. The thin film magnetic head of claim 4 wherein the easy axes of two pole pieces connected together by a distal via differ by substantially 30°

relative to each other, and the easy axes of two pole pieces connected together by a proximal via differ by substantially 120°

relative to each other.

6. A method for making a thin film magnetic transducer from a film having a plurality of layers, comprising the steps of:

forming a yoke having a plurality of magnetic flux circuits disposed about the center of the transducer such that there exists for each magnetic flux circuit two terminal end portions for coupling magnetic flux into and out of each magnetic flux circuit, each magnetic flux circuit being formed with a first pole piece in one layer of the film and a second pole piece in another layer of the film, forming the yoke comprising the steps of;

connecting the first and second pole pieces of each magnetic flux circuit together through a corresponding distal via traversing the layers of the film and disposed on a portion of the magnetic flux circuit distal to the terminal end portions relative to the center of the transducer;

connecting the terminal end portion of each magnetic flux circuit to a corresponding terminal end of an adjacent magnetic flux circuit through a corresponding proximal via traversing the layers of the film and disposed proximal to the center of the transducer; and

forming said pole pieces such that the easy axis of magnetization of each pole piece is oriented substantially perpendicular to a flux conduction path therein lying along a line of sight between the centers of the corresponding distal and proximal vias at opposite ends thereof, and such that the line of sight in the first pole piece and the line of sight in the second pole piece intersect at the distal via connecting the first and second pole pieces, said magnetic flux circuits being formed such that there are at least two pole pieces in each of said layers having non-parallel easy axes;

forming a first tip pole piece having a pole tip in said one layer of the film such that one end of said first tip pole piece is adapted for positioning adjacent to a magnetic medium for coupling magnetic flux between the medium and the yoke, and such that the other end of the first tip pole piece is connected to a corresponding terminal end portion of an adjacent magnetic flux circuit through a corresponding proximal via;

forming a second tip pole piece having a pole tip in said other layer of the film such that one end of said second tip pole piece is adapted for positioning adjacent to the magnetic medium for coupling magnetic flux between the medium and the yoke, and such that the other end of the second pole piece is connected to a corresponding terminal end portion of an adjacent magnetic flux circuit through a corresponding proximal via; and

forming a coil to have a plurality of turn intertwined with the yoke and passing between the distal and proximal vias, so that the distal vias are exterior to the coil and the proximal vias are interior to the coil, to provide at least four magnetic flux interactions between the coil and the yoke.

7. The method for making the thin film magnetic transducer of claim 6 wherein the transducer has a lateral axis perpendicular to the longitudinal axis and the orienting step comprises orienting the easy axis of a plurality of the pole pieces to form an oblique angle of between 10°

and 20°

with the lateral axis of the transducer.

8. The method for making the thin film magnetic transducer of claim 7 wherein the orienting step comprises orienting the easy axis of a plurality of the pole pieces to form an oblique angle of substantially 15°

with the lateral axis of the transducer.

9. The method for making the thin film magnetic transducer of claim 6 wherein the orienting step comprises orienting the easy axis of a plurality of the pole pieces to form an oblique angle of between 10°

and 20°

with the longitudinal axis of the transducer.

10. The method for making the thin film magnetic transducer of claim 9 wherein the orienting step comprises orienting the easy axis of a plurality of the pole pieces to form an oblique angle of substantially 15°

with the longitudinal axis of the transducer.

11. The method for making the thin film magnetic transducer of claim 6 wherein the transducer has a lateral axis perpendicular to the longitudinal axis and the orienting step comprises

orienting the easy axis of a plurality of the pole pieces to form an oblique angle of between 10°

and 20°

with the lateral axis of the transducer, and

orienting the easy axis of a plurality of the pole pieces to form an oblique angle of between 10° and

20°

with the longitudinal axis of the transducer.

12. A method for manufacturing a thin film magnetic transducer from a film having a plurality of layers, comprising the steps of

first depositing at least one magnetic pole piece onto the first layer of a substrate in the presence of a magnetic field to induce an easy axis in the deposited pole pieces having a first orientation substantially perpendicular to a flux conduction path lying along a line of sight extending between the respective centers of two spaced-apart areas where vias are to be subsequently formed on each firstly deposited pole piece,

reorienting the substrate relative to the magnetic field and secondly depositing at least one magnetic pole piece onto the first layer of the substrate in the presence of the magnetic field to induce an easy axis in the second deposited pole pieces having a second orientation different from said first orientation and substantially perpendicular to a flux conduction path lying along a line of sight extending between the respective centers of two spaced-apart areas where vias are to be subsequently formed on each secondly deposited pole piece,

forming at least one electrical coil layer onto the first layer of the substrate, and at least one insulating layer onto the electrical coil layer of the substrate, said insulating layer being formed with an opening above each area on the firstly and secondly deposited pole pieces where one of said vias is to be formed,

reorienting the substrate relative to the magnetic field and thirdly depositing at least one magnetic pole piece onto the insulating layer of the substrate, each thirdly deposited pole piece covering two of said insulating layer openings such that corresponding ones of said vias are thereby formed, and each thirdly deposited pole piece being deposited in the presence of the magnetic field to induce an easy axis therein having a third orientation substantially perpendicular to a flux conduction path lying along a line of sight extending between the respective centers of the vias formed thereby, and

reorienting the substrate relative to the magnetic field and fourthly depositing at least one magnetic pole piece onto the insulating layer of the substrate, each fourthly deposited pole piece covering two of said insulating layer openings such that corresponding ones of said vias are thereby formed, and each fourthly deposited pole piece being deposited in the presence of the magnetic field to induce an easy axis therein having a fourth orientation different from said third orientation and substantially perpendicular to a flux conduction path lying along a line of sight extending between the respective centers of the vias formed thereby.

13. The method for manufacturing the thin film magnetic transducer of claim 12, wherein the first and third orientations are different from one another.

14. The method for manufacturing the thin film magnetic transducer of claim 12, wherein

forming the electrical coil layer further comprises hard baking the substrate, and

the first and second depositing pole piece steps each further comprise the step of adjusting the orientation of the substrate relative to the magnetic field to compensate for reduction in the first and second easy axis orientations due to the hard baking step.

15. The method for manufacturing the thin film magnetic transducer of claim 12, wherein the pole pieces comprise NiFe.