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
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
  • G11B5/584—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes
• • 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
  • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
  • G11B5/3109—Details
  • G11B5/3116—Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks
• • 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
  • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
  • G11B5/3163—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
• • 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
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
• • 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
  • G11B5/23—Gap features
• • 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
  • G11B5/23—Gap features
  • G11B5/232—Manufacture of gap
• • 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
  • G11B5/295—Manufacture
• • 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
  • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
  • G11B5/3109—Details
  • G11B5/313—Disposition of layers
  • G11B5/3133—Disposition of layers including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure
• • 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
  • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
  • G11B5/3163—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
  • G11B5/3166—Testing or indicating in relation thereto, e.g. before the fabrication is completed
• • 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
  • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
  • G11B5/3176—Structure of heads comprising at least in the transducing gap regions two magnetic thin films disposed respectively at both sides of the gaps
  • G11B5/3179—Structure of heads comprising at least in the transducing gap regions two magnetic thin films disposed respectively at both sides of the gaps the films being mainly disposed in parallel planes
  • G11B5/3183—Structure of heads comprising at least in the transducing gap regions two magnetic thin films disposed respectively at both sides of the gaps the films being mainly disposed in parallel planes intersecting the gap plane, e.g. "horizontal head structure"

Definitions

• This invention relates generally to magnetic recording heads and more particularly to a method of making thin-film magnetic heads for imprinting servo patterns on a magnetic media.
• BACKGROUND OF THE INVENTION While a variety of data storage mediums are available, magnetic tape remains a preferred forum for economically storing large amounts of data. In order to facilitate the efficient use of this media, magnetic tape will have a plurality of data tracks extending in a transducing direction of the tape.
• one or more data read heads will read the data from those tracks as the tape advances, in the transducing direction, over the read head. It is generally not feasible to provide a separate read head for each data track, therefore, the read head(s) must move across the width of the tape (in a translating direction), and center themselves over individual data tracks. This translational movement must occur rapidly and accurately.
• a servo control system In order to facilitate the controlled movement of a read head across the width of the media, a servo control system is generally implemented.
• the servo control system consists of a dedicated servo track embedded in the magnetic media and a corresponding servo read head which correlates the movement of the data read heads.
• the servo track contains data, which when read by the servo read head is indicative of the relative position of the servo read head with respect to the magnetic media in a translating direction.
• the servo track was divided in half. Data was recorded in each half track, at different frequencies.
• the servo read head was approximately as wide as the width of a single half track. Therefore, the servo read head could determine its relative position by moving in a translating direction across the two half tracks. The relative strength of a particular frequency of data would indicate how much of the servo read head was located within that particular half track.
• the half track servo system While the half track servo system is operable, it is better suited to magnetic media where there is no contact between the storage medium and the read head.
• the tape actually contacts the head as it moves in a transducing direction. Both the tape and the head will deteriorate as a result of this frictional engagement; thus producing a relatively dirty environment. As such, debris will tend to accumulate on the read head which in turn causes the head to wear even more rapidly. Both the presence of debris and the wearing of the head have a tendency to reduce the efficiency and accuracy of the half track servo system.
• a timing-based servo pattern magnetic marks (transitions) are recorded in pairs within the servo track. Each mark of the pair will be angularly offset from the other. Virtually any pattern, other than parallel marks, could be used. For example, a diamond pattern has been suggested and employed with great success. The diamond will extend across the servo track in the translating direction. As the tape advances, the servo read head will detect a signal or pulse generated by the first edge of the first mark. Then, as the head passes over the second edge of the first mark, a signal of opposite polarity will be generated. Now, as the tape progresses no signal is generated until the first edge of the second mark is reached.
• a pulse of opposite polarity will be generated. This pattern is repeated indefinitely along the length of the servo track. Therefore, after the head has passed the second edge of the second mark, it will eventually arrive at another pair of marks. At this point, the time it took to move from the first mark to the second mark is recorded. Additionally, the time it took to move from the first mark (of the first pair) to the first mark of the second pair is similarly recorded. [008] By comparing these two time components, a ratio is determined. This ratio will be indicative of the position of the read head within the servo track, in the translating direction. As the read head moves in the translating direction, this ratio will vary continuously because of the angular offset of the marks.
• the servo read head is relatively small compared to the width of the servo track. Because position is determined by analyzing a ratio of two time/distance measurements, taken relatively close together, the system is able to provide accurate positional data, independent of the speed (or variance in speed) of the media.
• the system can further reduce the chance of error. As the servo read head scans the grouping, a known number of marks should be encountered. If that number is not detected, the system knows an error has occurred and various corrective measures may be employed. Once the position of the servo read head is accurately determined, the position of the various data read heads can be controlled and adjusted with a similar degree of accuracy.
• the servo track is generally written by the manufacturer. This results in a more consistent and continuous servo track, over time.
• a magnetic recording head bearing the particular angular pattern as its gap structure must be utilized. As it is advantageous to minimize the amount of tape that is dedicated to servo tracks, to allow for increased data storage, and it is necessary to write a very accurate pattern, a very small and very precise servo recording head must be fabricated.
• servo recording heads having a timing-based pattern have been created utilizing known plating and photolithographic techniques.
• a head substrate is created to form the base of the recording head.
• a pattern of photoresist is deposited onto that substrate.
• the photoresist pattern essentially forms the gap in the head. Therefore, the pattern will replicate the eventual timing-based pattern.
• a magnetically permeable material such as NiFe is plated around the photoresist pattern. Once so formed, the photoresist is washed away leaving a head having a thin film magnetic substrate with a predefined recording gap.
• broad beam ion milling is used to form a first layer having a relatively large gap.
• a pattern of photoresist is applied in an inverse of the above described pattern. That is, photoresist is applied everywhere except where the timing based pattern (gap) is to be formed. Ion milling is used to cut the gap through the first layer. Then an additional layer of the magnetically permeable material is deposited by plating over the first layer and a narrow gap is formed into this layer by the above described photolithographic process.
• This approach produces a more complicated head with a horizontally-processed or pancake-style thin film coil.
• the broad beam ion milling of the write pole does not produce an optimal gap structure.
• the photoresist pattern can be applied relatively precisely, thereby forming a channel over the gap.
• the traditional ion milling technique is rather imprecise and as the ions pass through that channel they are continuously being deflected.
• the relative aspect ratios involved prevent a precise gap from being defined. In other words, this is a shadowing effect created by the photoresist and causes the gap in the magnetically permeable material to be angled.
• the sidewalls of the gap will range between 45°-60° from horizontal. This introduces a variance into the magnetic flux as it exits the gap, resulting in a less precise timing based pattern being recorded onto the servo track.
• the present invention in one embodiment, is a magnetic recording head for generating servo tracks on a magnetic medium.
• the magnetic recording head includes a substrate having a generally planar first surface and a magnetically-permeable thin film deposited onto the first surface.
• a gap pattern is defined by the thin film, and the gap has corresponding termination patterns having at least one curved portion.
• the present invention is a gap pattern for a magnetic recording head.
• the gap pattern includes a pair of non-parallel, longitudinally extending gaps having a width and terminating in at least one termination pattern, wherein the termination pattern has at least one curved portion.
• BRIEF DESCRIPTION OF THE DRAWINGS [018]
• Figure 1 is a side planar view of a substrate bearing a magnetic thin film.
• Figure 2 is a top planar view of the substrate shown in Figure 1.
• Figure 3 is top planar view of a portion of thin film, bearing indicia of a gap to be milled.
• Figure 4 is a schematic diagram of a FIB milling a gap into a thin film.
• Figure 5 is a top planar view of a thin film having gaps milled by a FIB.
• Figure 6 is a side sectional view taken about line VI- VI.
• Figure 7 is a top planar view of a thin film having gaps milled by a FIB.
• Figure 8 is side sectional view taken about line VII- VII.
• Figure 9A is a top planar view of a portion of thin film having a gap and endpoints milled by a FIB.
• Figures 9B-9E show various configurations for the termination patterns or endpoints shown in Figure 9A.
• Figure 9F shows an effect of a termination pattern configured to include a rounded pattern.
• Figure 9G shows an effect of a termination pattern configured with only sharp corners.
• Figure 10 is a top planar view of a substrate bearing gaps and air bleed slots.
• Figure 11 is an end planar view of a substrate bearing air bleed slots.
• Figure 12 is a side planar view of a magnetic recording head.
• Figure 13 is an end planar view of a magnetic recording head.
• Figure 14 is a partial perspective view of thin film layer bearing a set of time based or angled recording gap pairs.
• Figure 15 shows an exemplary configuration of a terminating pattern with circular endpoints of an amplitude-based servo head.
• the present invention is a method of making a thin film magnetic recording head using a focused ion beam ("FIB") to mill out gaps in the tape bearing surface.
• FIB focused ion beam
• a substrate 10 is created by glass bonding two C-shaped ferrite blocks 12 to a medially disposed ceramic member 14.
• the sizes and relative proportions of the ferrite blocks 12 and ceramic member 14 may vary as dictated by the desired parameters of the completed recording head. Furthermore, the choice of materials may also vary so long as blocks 12 remain magnetic while member 14 remains magnetically impermeable.
• a layer of magnetically permeable material is deposited as a thin film 16 across an upper surface of each of the ferrite blocks 12, as well as the upper surface of the ceramic member 14.
• the magnetically permeable thin film 16 will become the tape bearing and data writing surface for the magnetic head 5 (see Figs. 12 & 13).
• An exemplary material for this purpose is FeN or alternatively SendustTM.
• FeN has a magnetic moment density on the order of 19 to 20 kGauss and is resistant to the fractional deterioration caused by continuous tape engagement.
• FeXN denotes the members of this family, wherein X is a single element or a combination of elements, as is known in the art.
• FeXN is created by sputtering a FeX alloy (or simply Fe) in a nitrogen rich environment. It is not available in quantities sufficient for plating. Furthermore, even if so available, the FeXN would decompose during the electrolytic plating process. This is in stark contrast to the simple alloys which may be readily utilized in electrolytic plating techniques. Therefore, while it is advantageous to use alloys, such as FeXN, magnetic recording heads cannot be formed with them, in any previously known plating process. In addition, the most desirable alloys to use are often composed of three of more elements. Plating is generally limited to the so called binary alloys, and as explained above is not conducive to binary gaseous alloys, such as FeN.
• sputtering in combination with the use of a FIB, not only allows any of these materials to be used but also produces a better wearing magnetic thin film with a higher saturation flux density and of sufficient permeability for use as a servo write head.
• the thin film 16 is sputtered onto the surface of the ferrite blocks 12 and the ceramic member 14.
• the surface Prior to the sputtering process, the surface is polished and prepared in a manner known to those skilled in the art. If desired, the surface may be ground to produce a slight curvature. This curvature will facilitate smooth contact between the tape and the completed head 5 as the tape moves across the tape bearing surface.
• the thickness of the deposited thin film 16 determines the efficiency of the magnetic head and also its predicted wear life. The thicker the tape bearing surface (thin film 16) is, the longer the head will last. Conversely, the thicker the magnetic film, the longer it will take to process or etch with a FIB and it will also process less precisely. Therefore, the thin film should be deposited in a thickness of about 1 to 5mm. Ideally, the thickness will be about 2 to 3 mm.
• Figure 2 is a top view of the substrate 10 and in particular the major surface of magnetic thin film 16 with the underlying ceramic member 14 shown in dashed lines.
• the area 18 is defined by the upper surface of the ceramic member 14 (the magnetic sub-gap) and is where the appropriate gaps will eventually be milled.
• indicia 20 is simply an indication of where the FIB is to mill.
• One way of accomplishing this is to place a layer of photoresist 22 down and define the indicia 20 with a mask. Using the known techniques of photolithography, a layer of photoresist 22 will remain in all of area 18 except in the thin diamond defined by indicia 20. Alternatively, the photoresist area could be substantially smaller than area 18, so long as it is sufficient to define indicia 20.
• the photoresist differs in color and height from the thin film 16 and therefore produces the visually discernible pattern.
• This pattern is then registered with the FIB control system through a graphical interface; thus delineating where the FEB is to mill.
• the photoresist serves no other purpose, in this process, than to visually identify a pattern.
• Any high resolution printing technique capable of marking (without abrading) the surface of the thin film 16 could be used.
• the pattern could be created completely within the FIB control system. That is, numerical coordinates controlling the path of the FIB and representing the pattern could be entered; thus, obviating the need for any visual indicia to be placed onto the magnetic thin film 16.
• a visual pattern could be superimposed optically onto the FIB graphical image of the substrate 10, thereby producing a visually definable region to mill without actually imprinting any indicia onto the substrate 10.
• the FIB 24 is programmed to trace a predefined pattern, such as the diamond indicia 20 shown in Figure 3.
• the FIB will be orientated in a plane orthogonal to the major surface of the thin film 16.
• Figure 4 is a sectional view of Figure 3, taken about line IV-IV and illustrates the milling process utilizing FIB 24.
• the upper surface of the thin film 16 has been coated with a thin layer of photoresist 22.
• the visual indicia 20 of the diamond pattern is present, due to the area of that indicia 20 being void of photoresist.
• the FIB 24 has already milled a portion of the pattern forming gap 30.
• the FIB as shown has just begun to mill the right half of the pattern.
• the beam of ions 26 is precisely controlled by the predefined pattern which has been entered into the FIB's control system. As such, the beam 26 will raster back and forth within the area indicated by indicia 20.
• the beam 26 will generally not contact a significant amount of the photoresist 22 and will create a gap 30 having vertical or nearly vertical side walls.
• the width of the ion beam is controllable and could be set to leave a predefined amount of space between the edge of the side wall and the edge of the indicia 20.
• the FIB 24 will raster back and forth until all of the indicia 20 have been milled for that particular head. [045] After the FIB 24 has milled all of the gap(s) 30, the photoresist 22 is washed away. Alternatively, any other indicia used would likewise be removed.
• Figure 5 illustrates area 18 of substrate 10 after the photo resist 22 has been removed.
• Thin film 16 is exposed and has precisely defined gaps 30 milled through its entire depth, down to the ceramic member 14.
• Figure 6 is a sectional view of Figure 5 taken about line VI- VI of Figure 5 and illustrates the milled surface of gap 30.
• the gap 30 is precisely defined, having vertical or nearly vertical walls.
• FIG 14 a partial perspective view of a time based recording head 5 is shown.
• the major surface 50 of thin film 16 lies in a plane defined by width W, length L, and depth D.
• D is the deposited thickness of the magnetic film 16.
• the FIB will always mill through thin film 16 through a plane substantially perpendicular to the major surface 50 which would also be parallel to depth D.
• the gap 30 will have a magnetic gap depth equal to depth D, the thickness of the deposited film, and a gap width equal to width W and a gap length (L')equal to the span of gap 30 in the direction shown.
• the upper surface of thin film 16, shown in Figure 7, represents one of many alternative time based patterns which may be created using a FIB 24.
• FIG. 8 is a sectional view taken about line VII- VII of Figure 7 and shows how gap 30 continues to have precisely defined practically vertical sidewalls. Furthermore, the upper horizontal surface 32 of ceramic member 14 is also precisely defined.
• FIG. 9A illustrates yet another pattern which may be defined using FIB 24.
• gap 30 is in the shape of an augmented diamond. Rather than defining a diamond having connected corners, gap 30 is milled to have termination patterns or endpoints 34, 35, 36 and 37. Creating endpoints 34, 35, 36 and 37 increases the definition of the finished recorded pattern near the ends of the track by helping to maintain nearly the full magnetic field to the end of the pattern.
• Several different shapes are possible for the termination patterns or endpoints 34, 35, 36, and 37.
• the rectangular shape shown in 9A may result in writing of the magnetic media slightly outside of the gap pattern. Specifically, in these instances, the sharp corners may cause a high concentration of magnetic flux that causes writing of the magnetic media.
• the termination patterns or endpoints 34, 35, 36, 37 are formed using any technique known in the art.
• Figures 9B-9E show various configurations for the termination pattern or endpoint 34.
• the configuration shown in Figures 9B-9E may also be applied to one or more of the other termination patterns or endpoints 35, 36, and 37.
• the configurations shown in Figures 9B-9E include rounded corners to prevent build-up of magnetic flux, which in turn prevents writing outside of the gap pattern.
• the termination patterns may be used to terminate a gap pattern formed using any technique known in the art.
• the endpoint 34 is generally square-shaped and includes two inside corners 38a and 38b and two outside corners 38c and 38d. In the embodiment shown, the outside corners 38c, 38d are rounded by replacing the square corner with an arc.
• the arc is a partial circle (the remainder of which is shown by the dashed line) having a center set slightly in from the point of intersection of the two sides of the endpoint 34.
• the insider corners 38a, 38b are also rounded in the same manner as the outside corners 38c, 38d.
• the endpoint 34 is generally rectangular-shaped.
• the rounded corners are formed from a circle having a diameter of between about 10% and about 50% of the length of the side of the endpoint 34.
• the rounded corners are formed from a circle having a diameter of about 30% of the length of the side of the endpoint 34.
• the sides of the termination box or endpoint 34 are about 6.5 microns and the diameter of the circle used to round the corners is about 2 microns.
• the centers of the circles may be set about 5 microns apart.
• Figure 9C shown another configuration for the endpoint 34.
• all four corners 38a, 38b, 38c, 38d are rounded in the shape of three-quarters of a circle.
• the corners are rounded to correspond to a circle centered on or about the point of intersection of the sides of the endpoint 34.
• only the outside corners 38c, 38d are rounded as shown.
• the endpoint 34 is generally rectangular-shaped.
• Figure 9D shows another configuration of the endpoint 34 in which the corners are simply rounded using an arc corresponding to a quarter circle. Again, any of all of the corners 38a, 38b, 38c, 38d may be rounded.
• the diameter of the circle corresponding to the rounded corners shown in Figures 9C and 9D may vary.
• the circle has a diameter of between about 10% and about 50% of the length of the side of the endpoint 34.
• the circle has a diameter of about 30% of the length of the side of the endpoint 34.
• Figure 9E shows yet another configuration of the termination pattern or endpoint 34.
• the endpoint 34 may be defined by any curved surface 39.
• the endpoint 34 is a circle.
• the circle may have any diameter greater than the perpendicular distance between the walls of the gap 30.
• the diameter of the circle is from between about 1.1 to about 4 times greater than the perpendicular distance between opposing walls of the gap 30.
• the diameter of the circle is about 2 times greater than the perpendicular distance between opposing walls of the gap 30.
• the circle has a diameter of from about 5 to about 7 microns.
• Fig. 9A This diameter range of 5 to 7 microns approximates the effect of the similarly sized termination pattern configured as a rectangular box (as shown in Fig. 9A) in terms of keeping the magnetic flux from leaking around the track edges.
• Figs. 9B-9E prevent boxwriting.
• Fig. 9F which shows the effect of a termination pattern with rounded corners
• Fig. 9G which has termination corners without rounded corners.
• the next step in the fabrication process is to create air bleed slots 40 in the tape bearing surface of the substrate 10, as shown in Figure 10.
• substrate 10 Once substrate 10 has been fabricated into a recording head, magnetic tape will move across its upper surface in a transducing direction, as shown by Arrow B. Therefore, the air bleed slots 40 are cut perpendicular to the transducing direction.
• air entrain ent occurs. That is, air is trapped between the lower surface of the tape and the upper surface of the recording head.
• the magnetic tape comprised of magnetic particles affixed to a substrate, being substantially non- planar on a microscopic level.
• the first air bleed slot encountered serves to skive off the trapped air.
• Figure 11 is a side view of the substrate 10, as shown in Figure 10.
• the upper surface of the substrate 10 has a slight curvature or contour. This acts in concert with the air bleed slots to help maintain contact with the magnetic tape.
• the air bleed slots 40 are cut into the substrate 10 with a precise circular saw, as is known by those skilled in the art.
• the air bleed slots 40 are cut through thin film 16, which is present but not visible in Figure 11. Alternatively, the air bleed slots 40 could be cut prior to the thin film 16 having been deposited.
• Substrate 10 has been longitudinally cut, thus removing a substantial portion of the coupled C-shaped ferrite blocks 12 and ceramic member 14. This is an optional step which results in an easier integration of the coils and ferrite blocks.
• Figure 13 illustrate how a backing block 46 is bonded to substrate 10.
• the backing block 46 is composed of ferrite or another suitable magnetic material. Wiring is wrapped about the backing block ' 46 thus forming an electrical coil 48. With this step, the fabrication process has been completed and a magnetic recording head 5 has been produced.
• magnetic recording head 5 is secured to an appropriate head mount. Magnetic tape is caused to move over and in contact with the tape bearing surface of the head 5, which happens to be the thin film layer 16. At the appropriate periodic interval, electrical current is caused to flow through the coil 48. As a result, magnetic flux is caused to flow (clockwise or counterclockwise in Figure 13) through the back block 46, through the ferrite blocks 12, and through the magnetic thin film 16 (as the ceramic member 14 minimizes a direct flow from one ferrite block 12 to the other causing the magnetic flux to shunt through the permeable magnetic film).
• the width of the head 5 is substantially larger than a single patterned gap 30. This allows the recording head to bear a plurality of patterned gaps 30.
• Figure 10 illustrates a substrate 10 having five recording gaps 30 which could then write five servo tracks simultaneously. More or less can be utilized as desired and the final size of the head 5 can be adjusted to whatever parameters are required.
• the substrate 10 could remain whole and the coils could be added to the C-shaped ferrite blocks 12, as they are shown in Figure 1.
• the above head fabrication process has been described with respect to a magnetic recording head employing a timing-based servo pattern. However, the process could be applied equally well to any type of surface thin film recording head.
• the head fabrication process can be applied to an amplitude-based servo head.
• An exemplary configuration of a terminating pattern with circular endpoints of an amplitude-based servo head is shown in Figure 15. That is, those of ordinary skill in the art will appreciate that the FIB milling of the gaps could accommodate any shape or pattern, including the traditional single gap used in half-track servo tracks.

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• 2003
  • 2003-10-10 US US10/683,809 patent/US7196870B2/en not_active Expired - Fee Related
• 2004
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