US3928908A - Manufacture of magnetic heads - Google Patents

Manufacture of magnetic heads Download PDF

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Publication number
US3928908A
US3928908A US422684A US42268473A US3928908A US 3928908 A US3928908 A US 3928908A US 422684 A US422684 A US 422684A US 42268473 A US42268473 A US 42268473A US 3928908 A US3928908 A US 3928908A
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US
United States
Prior art keywords
magnetic
pole pieces
elements
working face
ferrite
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US422684A
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English (en)
Inventor
Derek Frank Case
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Individual
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Individual
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Publication of US3928908A publication Critical patent/US3928908A/en
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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/29—Structure or manufacture of unitary devices formed of plural heads for more than one track
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/1871—Shaping or contouring of the transducing or guiding surface
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/193—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features the pole pieces being ferrite or other magnetic particles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49027—Mounting preformed head/core onto other structure
    • Y10T29/4903—Mounting preformed head/core onto other structure with bonding
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49036—Fabricating head structure or component thereof including measuring or testing
    • Y10T29/49041—Fabricating head structure or component thereof including measuring or testing with significant slider/housing shaping or treating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49048—Machining magnetic material [e.g., grinding, etching, polishing]

Definitions

  • ABSTRACT A method is disclosed in which a pair of electrically non-conducting ferrite pole pieces for use in a magnetic transducing head are assembled together with a non-magnetic separator which defines a transducing gap and in which an electrically conductive film is applied around the pole pieces and the gap.
  • the pole pieces are subsequently encased in non-magnetic material to produce a working face in which the pole pieces and gap are surrounded firstly by the conduc tive layer and then by the non-magnetic material.
  • a ferrite block is similarly built up surrounded by a conductive layer and non-magnetic material and the block is then grooved to assume a U-shaped configuration.
  • the assemblies containing the pole pieces and the grooved ferrite block are then brought together so that the U-shaped block forms a yoke for the pole pieces.
  • the block assembly may be further grooved to permit a coil to be introduced over at least one limb of the yoke.
  • the present invention relates to methods of manufacturing magnetic transducing heads.
  • the present invention proposes a method of manufacture that permits the use of a conductive surround in conjunction with the insertion of the pole pieces of a head into a working face and avoids the problems associated with the fabrication of a conductive surround from discrete blocks.
  • a method of manufacturing a transducing head for use in conjunction with a magnetic recording medium having a working face arranged to be positioned in use adjacent the medium to co-operate therewith and having a pair of electrically non-conductive ferrite mangetic elements forming at the working face magnetic pole pieces separated by a non-magnetic spacer to provide a transducing gap
  • which method includes forming an electrically conductive layer as a closed loop about an axis substantially perpendicular to said working face, the loop circumscribing only the pole pieces and the spacer at least at and in the vicinity of the working face.
  • FIG. 1 shows a ferrite pole piece element
  • FIG. 2 shows the element with a conductive screening layer.
  • HO. 3 shows a number of screened elements assembled in a non-magnetic support.
  • FIG. 4 shows a pole piece assembly
  • FIG. 5 shows a screened ferrite yoke element.
  • FIG. 6 shows a number of screened yoke elements assembled in non-magnetic support.
  • FIG. 7 shows a yoke assembly
  • FIG. 8 shows a multi head assembly
  • a pole piece element l shown in FIG. 1 consists of two ferrite strips 2, 3 secured together with a non-magnetic gap 4 therebetween.
  • the element I may be produced by spacing two ferrite bars apart and introducing into the gap therebethickness to correspond to a required track width on a recording medium with which the finished magnetic head is subsequently to be associated.
  • the pole piece element 1 is then plated with copper 5, FIG. 2, initially by an electroless process and then by an electrolytic plating process to build up a layer of copper of the required thickness.
  • FIG. 3 shows a block from which pole piece assemblies for read and write heads for two tracks may be produced.
  • the plated pole piece elements 1 are positioned in grooves in non-magnatic blocks 6, 7 so that the elements I are spaced apart by the desired intertraek spacing.
  • the blocks 6, 7 are then secured together with a suitable spacer sandwiched therebetween.
  • the spacer consists of a pair of nonmagnetic plates 8, 9 and a magnetic plate 10 sandwiched between the plates 8, 9.
  • the pole piece elements 1 in the block 6 will subsequently be formed into poles of pairs of read heads and the poles piece elements 1 in the block 7 will subsequently be formed into poles of corresponding pairs of write heads,
  • the blocks 6, 7 may be formed of glass-ceramic material and the assembly is secured together by glass or a suitable synthetic resin adhesive.
  • Each slice 11 contains a portion of the length of each element 1 positioned in the required relative relationship by a similar portion of the length of the blocks 6, 7 and the spacer 8, 9, 10 as shown in more detail in FIG. 4.
  • One face 12 of the slice 11 is lapped and polished to a flat surface and the other face 13 is machined to a desired profile to act as a working face and which-will cause a recording medium such as a magnetic tape to contact the exposed ends of each pole piece I in the vicinity of its non-magnetic gap 4.
  • the elements 1 are machined from the face 12 so to remove parts of both pole pieces on each side of the gap 4 to reduce the depth through the thickness of the slice.
  • a yoke assembly for the above described pole piece assembly may be formed .in a similar manner.
  • Ferrite elements 14 (FIG. 5) having a cross section indentical to that of the elements 1 but without a non-magnetic gap, are plated with copper to provide a layer of copper 28 of required thickness extending around each element l4 and are positioned as shown in FIG. 6 in nonmagnetic blocks l5, 16.
  • the blocks l5, l6 are secured together with a spacer therebetween consisting of nonmagnetic plates 17, 18 and a magnetic plate 19.
  • the blocks 15, 16 may be of glass-ceramic material and the components of the yoke assembly are secured together by glass or a suitable synthetic resin adhesive.
  • the assembly is divided along spaced parallel planes, as shown in FIG. 6, to produce a plurality of slices 20, each slice containing a portion of the length of each ferrite element 14 supported in a similar portion of the blocks l5, l6 and spacers l7, l8, l9.
  • One face 2l of the slices is lapped and polished to produce a flat surface for co-operation with the lapped flat face l2 of the pole piece assembly and in addition is machined to cut grooves extending into the thickness of the slice from the face 21.
  • Two grooves 22 pass respectively each through a pair of ferrite elements 14 lying on the same side of the spacer l7, l8, 19 so as to form each of the ferrite elements 14 into U-shaped yokes, each yoke having two parallel limbs 23.
  • Two further grooves 24 are cut parallel to grooves 22 and four grooves 25 are out perpendicular to the grooves 22, 24.
  • the grooves 24, 25 extend in the blocks l5, 16 adjacent to but outside the U-shaped yokes so as to extend around three sides of one limb 23 of each of the U-shaped yokes and thereby provide together with grooves 22, recesses circumscribing the limb 23 of each yoke, into which recesses prewound coils 26 are place so as to electromagnetically couple with the yoke. If it is desired to place coils on each limb of the yokes, then additional grooves are cut, parallel to grooves 24, so as to form recesses around the other limbs to accomodate the additional coils. The leads 29 of the coil or coils are brought out along the grooves 25.
  • the pole piece assembly of P16. 4 is mounted with its lapped flat face 12 in intimate contact with the lapped face 21 of the yoke assembly 20 that each U shaped yoke 23 bridges the rear ends of the pole pieces 1 and the copper plating on the yokes -23 makes electrical contact with the corresponding copper plating on the pole pieces 1.
  • An electrical earthing connection is made to the copper plating on each yoke 23 by means of a conductive sheet 27 secured in contact with the rear face of the yoke assembly.
  • the above described method of manufacturing a magnetic head assembly provides closed conductive loops surrounding each pair of pole pieces at least at and in the vicinity of the working face 13 which act as eddy current shields effective to reduce the magnitude of magnetic flux link ing with the magnetic cores through the conductive loops. Furthermore the slotting of the ferrite elements 14 by the grooves 22 removes a portion of the copper plating and hence breaks the closed loop in the region of the yoke which is coupled to the coil 26 whilst providing conductive sheet 27 ensures that all the remaining portions of the copper plating are connected to earth.
  • the pole pieces and yokes are plated with copper
  • the method may be modified.
  • the plating on the yoke elements 14 need not extend completely around the elements and may be provided on one face only.
  • Conductive materials other than copper may be used for plating the pole pieces and yokes.
  • the pole piece elements may be shaped to the required profiles prior to plating and assembling in the nonmagnetic blocks so as to eliminate machining of the rear ends of the pole pieces when in the pole piece assembly if it is desired to produce pole tips of different section from the remainder of the pole pieces.
  • the ferrite elements 1 are machined to the required profile prior to plating with conductive material and the assembly of FIG. 3 is divided along precisely defined planes so that each slice contains the required profiled pole piece elements.
  • this form of structure merely extends the limbs of the U-shaped yokes 14 into the pole piece elements.
  • the magnetic cores may be formed of other magnetic materials such as mu-metal.
  • preformed laminations of mu-metal are bonded together and are then plated at least in the vicinity of the pole tips with a conductive layer to form a closed conductive loop circumscribing the pair of poles and the spacer in the transducing gap.
  • a method of manufacturing a transducing head for use in conjunction with a magnetic recording medium having a working face arranged to be positioned in use adjacent the medium to co-operate therewith, the method including the steps of assembling a pair of electrically non-conductive ferrite elements and a non-magnetic spacer so as to provide at the working face magnetic pole pieces separated by the nonmagnetic spacer the latter defining a transducing gap; depositing an electrically conductive layer over the assembled ferrite elements to provide a closed electrically conductive loop about an axis substantially perpendicular to the working face and such as to circumscribe only the pole pieces and the transducing gap at least in the vicinity of the working face, forming a nonmagnetic block grooved to receive the assembled elements; inserting the assembled elements with the conductive layer thereon into the groove with the spacer between the ferrite elements layer parallel to the axis of the groove; applying a plate of non-magnetic material to bridge the groove; and bonding the elements in the block and

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Magnetic Heads (AREA)
US422684A 1972-12-29 1973-12-07 Manufacture of magnetic heads Expired - Lifetime US3928908A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB6015272A GB1423520A (en) 1972-12-29 1972-12-29 Manufacture of magnetic transducing heads

Publications (1)

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US3928908A true US3928908A (en) 1975-12-30

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US422684A Expired - Lifetime US3928908A (en) 1972-12-29 1973-12-07 Manufacture of magnetic heads

Country Status (5)

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US (1) US3928908A (cs)
JP (1) JPS4999015A (cs)
FR (1) FR2212595B3 (cs)
GB (1) GB1423520A (cs)
NL (1) NL7317124A (cs)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030189A (en) * 1973-02-21 1977-06-21 Compagnie Internationale Pour L'informatique Method of making magnetic head devices
US4074331A (en) * 1975-10-03 1978-02-14 Burroughs Corporation Magnetic recording head structure for recording on both sides of a record member
US4107751A (en) * 1975-05-26 1978-08-15 Olympus Optical Co., Ltd. Magnetic head
US4152741A (en) * 1976-12-07 1979-05-01 Victor Company Of Japan, Ltd. Ferrite core magnetic head with improved reinforcement filler
US4246695A (en) * 1979-08-31 1981-01-27 Memorex Corporation Two rail slider assembly production technique for making thin film heads
US4291354A (en) * 1979-06-04 1981-09-22 Ampex Corporation Extended life multichannel magnetic transducer
US4320427A (en) * 1977-12-20 1982-03-16 Wolfgang Bogen Wear-resistant magnetic heads
US5048175A (en) * 1989-03-03 1991-09-17 Seagate Technology, Inc. Method for grounding pole structures in thin film magnetic heads
US6233812B1 (en) * 1997-03-05 2001-05-22 Matsushita Electric Industrial Co., Ltd. Rotary head device, magnetic head unit and manufacturing method thereof

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2800534A (en) * 1956-03-15 1957-07-23 Ibm Electromagnetic transducer
US3195119A (en) * 1962-12-31 1965-07-13 Burroughs Corp Magnetic transducer head assembly
US3384954A (en) * 1965-12-07 1968-05-28 Ibm Making multitrack magnetic transducer
US3601871A (en) * 1968-09-30 1971-08-31 Texas Instruments Inc Method for fabricating magnetic read-write head array and product

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2800534A (en) * 1956-03-15 1957-07-23 Ibm Electromagnetic transducer
US3195119A (en) * 1962-12-31 1965-07-13 Burroughs Corp Magnetic transducer head assembly
US3384954A (en) * 1965-12-07 1968-05-28 Ibm Making multitrack magnetic transducer
US3601871A (en) * 1968-09-30 1971-08-31 Texas Instruments Inc Method for fabricating magnetic read-write head array and product

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030189A (en) * 1973-02-21 1977-06-21 Compagnie Internationale Pour L'informatique Method of making magnetic head devices
US4107751A (en) * 1975-05-26 1978-08-15 Olympus Optical Co., Ltd. Magnetic head
US4074331A (en) * 1975-10-03 1978-02-14 Burroughs Corporation Magnetic recording head structure for recording on both sides of a record member
US4152741A (en) * 1976-12-07 1979-05-01 Victor Company Of Japan, Ltd. Ferrite core magnetic head with improved reinforcement filler
US4320427A (en) * 1977-12-20 1982-03-16 Wolfgang Bogen Wear-resistant magnetic heads
US4291354A (en) * 1979-06-04 1981-09-22 Ampex Corporation Extended life multichannel magnetic transducer
US4246695A (en) * 1979-08-31 1981-01-27 Memorex Corporation Two rail slider assembly production technique for making thin film heads
US5048175A (en) * 1989-03-03 1991-09-17 Seagate Technology, Inc. Method for grounding pole structures in thin film magnetic heads
US6233812B1 (en) * 1997-03-05 2001-05-22 Matsushita Electric Industrial Co., Ltd. Rotary head device, magnetic head unit and manufacturing method thereof

Also Published As

Publication number Publication date
FR2212595B3 (cs) 1976-10-15
GB1423520A (en) 1976-02-04
NL7317124A (cs) 1974-07-02
JPS4999015A (cs) 1974-09-19
FR2212595A1 (cs) 1974-07-26

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