JP2006260661A - Method for manufacturing magnetic transfer master disk, and magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic transfer master disk, capable of reducing the size of a burr generated during the punching of a master substrate as much as possible so as to prevent adhesion to a slave disk from being damaged, and a magnetic recording medium to which good information is magnetically transferred. <P>SOLUTION: In the punching process of a master substrate 11, a punching tool 40 constituted of a fixed blade 42 and a moving blade 45 is used to move the moving blade 45 or the fixed blade 42 relatively to the metal board 18 toward the backside from the front side of the metal board 18 in which a recessed and projected pattern P is formed, thereby the metal board 18 is punchced into the master substrate 11 of a predetermined shape. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a magnetic transfer master disk and a magnetic recording medium, and more particularly to a method of manufacturing a magnetic transfer master disk suitable for transferring magnetic information such as format information to a magnetic disk used in a hard disk device or the like. and a magnetic recording medium.

  In recent years, magnetic disks (hard disks) used in hard disk drives, which have been rapidly spreading, have been formatted and addressed as preformat information before being installed in the drive after being delivered to the drive manufacturer by the magnetic disk manufacturer. Generally written. Although this writing can be performed by a magnetic head, a method of batch transfer from a master disk in which format information and address information are written is efficient and preferable.

  Magnetic transfer method of this batch transfer, magnetic transfer master disk (hereinafter, sometimes referred to as master disk only) and a transfer disk (hereinafter, sometimes referred to as a magnetic recording medium or a slave disc) and are brought into close contact with in state, the electromagnetic device on one or both sides, by applying a transfer magnetic field by disposing the magnetic field generating means such as a permanent magnet system, for magnetically transferring information included in the master disk (e.g. a servo signal) to the slave disk . Then, the magnetic transfer accurately, it is extremely important to adhere uniformly without gaps between the master disk and the slave disk.

By the way, as a master disk used in this magnetic transfer method, a master disk in which a concave / convex pattern corresponding to an information signal is formed on the surface of a master substrate and a magnetic layer is coated on the surface of the concave / convex pattern is usually used. This master disk for magnetic transfer is electroformed by performing electroforming on a master disk on which information is formed in a concavo-convex pattern, and laminating a metal disk composed of an electroformed layer on the master disk, and transferring the concavo-convex pattern onto the surface of the metal disk. In general, it is manufactured by coating a magnetic layer on the surface of the concavo-convex pattern after passing through a process, a peeling process for peeling the metal disk from the master, and a punching process for punching the peeled metal disk to a predetermined size. (e.g., see Patent Document 1.).
JP 2001-256644 JP

  Incidentally, in the above punching process, a stationary blade and the moving blade performs the punching of the perforations and the outer periphery of the metal plate of the center hole in the punching tool became pair, burr occurs in the punching portion of the center hole and the outer periphery.

  In punching working of general metal plate, the height of the burrs formed in punching portion by punching tool is a quality good if approximately 0.1mm or less, as a master substrate of the master disk for magnetic transfer is Even with a burr of about 5 μm, the adhesion to the slave disk during magnetic transfer deteriorates, and the transferred signal strength decreases due to the spacing between the master disk and the slave disk, resulting in good transfer. There was a problem that it was not done.

  To enhance the adhesion between the master disk and the slave disk, a method to improve the adhesion pressure is considered, to increase the adhesion pressure may cause the damage of the concavo-convex pattern formed on the master disk or deformed , it causes to reduce the durability of the master disk.

  For this reason, it is strictly required to reduce the occurrence rate and burr height of the master substrate that impairs the adhesion between the master disk and the slave disk to the limit.

  The present invention has been made in view of such circumstances, and in a method for manufacturing a master disk for magnetic transfer, which punches a metal disk having a concavo-convex pattern corresponding to an information signal to manufacture a master substrate of a predetermined shape, In addition to providing a method for manufacturing a master disk for magnetic transfer that reduces the size of burrs that are sometimes generated, and does not impair the adhesion to the slave disk, and also provides a magnetic recording medium on which good preformat information is magnetically transferred. and an object thereof.

  In order to achieve the above object, claim 1 of the present invention is a method in which a metal disk having a predetermined thickness is laminated by electroforming or the like on a master having a concavo-convex pattern according to transfer information, and the metal is peeled off from the master. In a method of manufacturing a master disk for magnetic transfer in which a disk is punched into a predetermined shape to form a master substrate, and a magnetic layer is formed on the concave and convex pattern of the master substrate, the punching includes a fixed blade and a movable blade Using a punching tool, the moving blade or the fixed blade is moved relative to the metal plate from the front side to the back side where the concave and convex pattern of the metal plate is formed. It is characterized by punching.

  According to the present invention, since punching the cutting edge of the punching tool relative to proceed toward the back side from the concavo-convex pattern formed surface side of the metal plate, the burr generated in stamping section It can be formed on the back surface of the master substrate. For this reason, a convex part is not formed in the side which contacts a slave disk. Further, the back surface of the master substrate can be deburred.

  According to a second aspect of the present invention, in the first aspect of the invention, by adjusting a clearance between the fixed blade and the movable blade, the size of the burr formed on the back surface of the master substrate during punching is adjusted. and it features.

  According to invention of Claim 2, the magnitude | size of the burr | flash formed in the back surface of a master board | substrate can be reduced by setting the clearance of the said fixed blade and moving blade of a punching tool optimally.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a relative punching stroke of the movable blade or the fixed blade with respect to the metal plate is determined. The distance from the position in contact with the surface to the position where the metal plate is punched into a predetermined shape is set as an additional distance, and the punching stroke is set so that the additional distance becomes a predetermined value.

  In general, stamping, in order to reduce the burr occurring on the punched portion is preferably set punching stroke (pushing amount of the cutting edge to the workpiece) in the last minute which a workpiece is cut, claims According to the invention of 3, since the punching stroke can be set optimally, burrs generated in the punched portion can be reduced.

  According to a fourth aspect of the present invention, in the invention according to any one of the first, second, or third aspect, the back surface of the stamped master substrate is polished.

  According to the invention of claim 4, since polishing the back surface of the master substrate which is stamped, as well as reduce the burr formed on the back surface, burr Hakare height leveling, further master substrate the entire back surface flat Therefore, the contact with the slave disk at the time of magnetic transfer becomes uniform.

  A magnetic recording medium according to a fifth aspect of the present invention is a magnetic transfer master disk manufactured by the method for manufacturing a magnetic transfer master disk according to any one of the first to fourth aspects. The magnetic recording medium is characterized in that the preformat information is magnetically transferred.

  According to the invention of claim 5, since information is magnetically transferred using a magnetic transfer master disk having excellent adhesion, a good preformat information signal can be obtained.

  As described above, according to the method for manufacturing a magnetic transfer master disk and the magnetic recording medium according to the present invention, the master board of the magnetic transfer master disk is punched out from the metal disk having the concavo-convex pattern corresponding to the transfer information. When manufacturing, the cutting blade of the punching tool is relatively advanced from the front side to the back side where the concavo-convex pattern is formed on the metal plate, and punching is performed. Can be formed. For this reason, a convex part is not formed in the side which contacts a slave disk. Further, the back surface of the master substrate can be deburred. Further, since the preformat information is magnetically recorded on the magnetic recording medium using the magnetic transfer master disk manufactured by this manufacturing method, a good preformat information signal can be obtained.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for manufacturing a magnetic transfer master disk and a magnetic recording medium according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a partial perspective view of a magnetic transfer master disk 10 (hereinafter sometimes simply referred to as a master disk 10), and FIG. 2 is a cross-sectional view taken along the line AA of FIG. The transferred disk (slave disk 14) is indicated by an imaginary line.

  As shown in FIGS. 1 and 2, the master disk 10 is composed of a metal master substrate 11 and a magnetic layer 12, and a fine uneven pattern P (for example, servo information) corresponding to transfer information on the surface of the master substrate 11. Pattern) and the magnetic layer 12 is coated on the concavo-convex pattern P.

  Thus, the information carrying surface 13 having a fine concavo-convex pattern P on which the magnetic layer 12 is coated on one surface of the master substrate 11 is formed. As can be seen from Figure 1, the fine concavo-convex pattern P is rectangular in plan view, the length p in the track direction (arrow direction in the figure) in a state where the magnetic layer 12 is formed, the radial length made by and L.

  The optimum values of the length p and the length L vary depending on the recording density and the recording signal waveform. For example, the length p can be 80 nm and the length L can be 200 nm. In the case of a servo signal, the fine uneven pattern P is formed long in the radial direction. In this case, for example, the length L in the radial direction is preferably 0.05 to 20 μm, and the length p in the track direction (circumferential direction) is preferably 0.01 to 5 μm.

  It is preferable for the pattern carrying the servo signal to select the concave / convex pattern P that is longer in the radial direction within this range. The depth t (projection height) of the concavo-convex pattern P is preferably in the range of 30 to 800 nm, and more preferably in the range of 50 to 300 nm.

  As shown in FIG. 3, the master substrate 11 is formed in a disk shape having a center hole 11G, and has an annular shape excluding the inner peripheral portion 11D and the outer peripheral portion 11E on one side (information carrying surface 13). The uneven pattern P is formed in the region 11F. The details of the production of the master substrate 11 will be described later. Mainly, the master disk 11 is formed by electroforming a master disk on which information is formed by the concavo-convex pattern P, and a metal disk made of an electroformed layer is formed on the master disk. Are manufactured by an electroforming process for transferring the concavo-convex pattern P, a peeling process for peeling the metal disk from the master, and a punching process for punching the peeled metal disk into a predetermined shape.

  In the present invention, various types of metals and alloys can be used as the electroformed layer. In the present embodiment, an example of a Ni electroformed layer will be described below as a preferable example. The Ni electroformed layer is order to have flexibility, so as to have a predetermined crystal structure, electroformed while controlling the current density during electroforming.

  Next, a method for manufacturing the master disk 10 of the present invention configured as described above will be described in detail.

  FIG. 4 is a process diagram showing steps for manufacturing the master disk 10. First, as shown in FIG. 4A, a pretreatment such as formation of an adhesion layer is performed on an original plate 15 (a glass plate or a quartz plate may be used) made of a silicone wafer having a smooth and clean surface. Is applied by spin coating or the like to form a resist film 16 and baked.

  Then, an electron beam exposure apparatus (not shown) equipped with a high-precision rotary stage or XY stage irradiates the original plate 15 mounted on the stage with an electron beam B modulated in accordance with a servo signal or the like. Then, a desired concavo-convex pattern P ′ is drawn and exposed on the resist film 16.

  Next, as shown in FIG. 4B, the resist film 16 is developed, and a desired concavo-convex pattern P ′ is formed by the remaining resist film 16 after removing the exposed portion. By on the concavo-convex pattern P 'example Sutapparingu grant Ni conductive film (not shown) to produce a electroforming can matrix 17.

  Next, as shown the matrix 17 in FIG. 4 (c), subjected to whole surface electroforming apparatus in electroforming the master 17, laminating the desired thickness of the metal plate 18 (Ni electroformed layer) with Ni metal . Ni has a crystal structure of face-electroforming so as to have a predetermined crystal structure by controlling the current density during electroforming.

  In the present invention, in the lamination of the metal plate 18 by electroforming, a crystal structure is defined so that a flexible Ni electroformed layer is formed. That is, the desired crystal by changing the current density of the current supplied to matrix 17 which Ni conductive film is applied while rotating at a rotational speed of 50~150rpm by immersion in Ni electroforming bath in the Ni electroforming bath An electroformed layer having a structure is formed.

  Usually, the metal used for the master disk 10 is nickel (Ni), when produced in the electroforming master disk 10, the use of small master substrate 11 is easily obtained nickel sulfamate bath stress It is preferred.

  Nickel sulfamate bath, for example, nickel sulfamate 400 to 800 / L, depending on the borate required for 20 to 50 g / L (supersaturation) based as a surfactant (e.g. sodium lauryl sulfate) additives such as It is what was added. The bath temperature of the plating bath is preferably 40 to 60 ° C. It is preferable to use a nickel ball in a titanium case for the counter electrode during electroforming.

  Then, the metal plate 18 is peeled from the master 17, is removed and cleaned the resist film 16 remaining. Thus, as shown in FIG. 4 (d), having a concavo-convex pattern P that is inverted, and the original plate 11 of a master substrate 11 having an outer diameter D before punching into a predetermined size 'is obtained.

  This master plate 11 ′ is punched to obtain a master substrate 11 of a predetermined size having an outer diameter d shown in FIG. 4 (e). The master disk 10 can be manufactured by forming the magnetic layer 12 on the concave / convex pattern surface of the master substrate 11.

  As another manufacturing process of the master disk 10, the master 17 is electroformed to produce a second master. Then, electrocasting is performed using the second master, a metal disk having an inverted concavo-convex pattern P is produced, and the master board 11 may be punched into a predetermined size.

  Furthermore, whether to electroforming the second original disk, unevenness performing curing presses the resin solution to prepare a third master, performing electroforming to produce a metal plate 18 to the third original disk, and further inverted punched into a predetermined size by peeling off the metal disk 18 having a pattern P, or as a master substrate 11. The second repeated using master or the third original disk, it is possible to produce a plurality of metal disk 18.

  In the production of the master, the resist film may be removed after the resist film is exposed and developed, and then subjected to an etching process to form an uneven pattern P ′ by etching on the surface of the master.

  In the punching process of the original plate 11 ′ made of the metal plate 18, burrs are generated in the punched portion, and how to reduce the burrs is an important issue. FIG. 5 shows a punching tool used in the method of manufacturing a master disk for magnetic transfer according to the present invention.

  As shown in FIG. 5, the punching tool 40 includes a lower die set 40A and an upper die set 40B. The lower die set 40A is a fixed die set, and the upper die set 40B is a moving die set.

  The lower die set 40A includes a base 41, a ring-shaped lower die 42 that is a fixed blade fixed to the upper surface of the base 41 with a screw, and a ring-shaped spacer 44 on the base 41 surrounding the outer periphery of the lower die 42. And a ring-shaped mounting table 43 fixed with screws.

  The inner peripheral edge portion of the upper surface of the lower die 42 functions as the center hole lower blade 42a, and the outer peripheral edge portion functions as the outer peripheral lower blade 42b. Further, in the center of the base 41, the punched scrap a hole 41a to fall is formed when punching the center hole 11G of the master substrate 11.

  The upper die set 40B includes an upper die 45 that is a moving blade, a knockout plate 46, and the like. The upper die 45 has a disk shape, and a circumferential groove 45G is formed on the lower surface leaving the center portion and the outer peripheral periphery. The upper surface inner edge portion of the circumferential groove 45G functions as the center hole upper blade 45a, and the upper surface outer edge. The portion functions as the outer peripheral upper blade 45b.

  The knockout plate 46 has a ring shape and is guided by three stepped guide pins 47 provided on the circumference, and is supported so as to be vertically movable in the circumferential groove 45G. The knockout plate 46 is pressed downward by three compression coil springs 48 provided on the circumference.

  In the present invention, the master substrate 11 is placed on the upper surface of the mounting table 43 with the surface side of the master plate 11 ′ on which the concave / convex pattern P is formed facing upward and the back surface side facing down, and within the surface of the lower die 42. Fix with a plurality of embedded magnets (not shown). Thereby, since the uneven pattern P of the original plate 11 ′ is punched from the surface side to the lower surface side, burrs generated in the punched portion can be formed on the back surface side.

  In the present invention, the size of the burr is reduced by adjusting the clearance between the upper blade and the lower blade. If this clearance is too large or too small, burrs will not be reduced. Specifically, the lower side is set so that ½ of the difference between the inner diameter d2 of the center hole lower blade 42a and the outer diameter d4 of the center hole upper blade 45a is 1 to 15 μm, preferably 5 to 10 μm. Die 42 and upper die 45 are created.

  FIG. 6 conceptually shows how the center hole 11G of the master plate 11 ′ of the master substrate 11 is punched. As shown in FIG. 6, the center hole upper blade 45a is pushed in from the surface side of the original plate 11 'to punch out the center hole 11G. At this time, a plastic deformation sag portion DA is formed on the front surface side of the original plate 11 ', and burrs BA are generated on the back surface side due to plastic fracture. Since FIG. 6 is a conceptual diagram for explaining the burr BA, the positional relationship in the vertical direction between the original plate 11 ′ and the upper die 45 is intentionally shifted in order to express the burr BA in an easy-to-understand manner.

  The sizes of the plastic deformation sag portion DA and the burr BA depend on the value of the clearance C between the center hole lower blade 42a and the center hole upper blade 45a. The smaller the value of this clearance C is, the better it is not. If it is too small, the height of the burr BA increases.

  Further, the lower die 42 and the upper die are set so that ½ of the difference between the inner diameter dimension d3 of the outer peripheral upper blade 45b and the outer diameter dimension d1 of the outer peripheral lower blade 42b is 2 to 30 μm, preferably 5 to 20 μm. to create a 45.

  In the present invention, the step between the upper surface of the lower die 42 and the upper surface of the mounting table 43 is adjusted within ± 0.5 mm, preferably within ± 0.2 mm. This adjustment is performed by adjusting the thickness of the spacer 44 laid on the lower surface of the mounting table 43.

  In the present invention, when punching stroke (on a center hole edge 45a and the outer peripheral edge 45b of the upper die 45 has a contact position in the original plate 11 'of the master substrate 11 to 0, the upper therefrom The amount of pressing of the die 45) is the distance from the position where the center hole upper blade 45a and the outer peripheral upper blade 45b are in contact with the original plate 11 ′ of the master substrate 11 to the position where the original plate 11 ′ is punched, plus an additional distance, This additional distance is set to a predetermined value. Specifically, the thickness is set in the range of the thickness of the original plate 11 ′ plus 1.0 to 5.0 according to the outer diameter size of the master substrate 11.

  'When the punching of the first original plate 11' original plate 11 of the master substrate 11 a concavo-convex pattern P is stuck to the protective sheet on the surface side formed of, protecting the surface of the concavo-convex pattern P is formed in the original plate 11 ' . As the protective sheet, a trade name product manufactured by Trileyna, a product name KL sheet manufactured by Nitto Denko Corporation, or the like is used.

  Next, the original plate 11 ′ is placed on the lower die 42 and the mounting table 43 with the protective sheet side facing up, and fixed with a magnet. Then the upper die 45 has lowered, first knockout plate 46 'contacts the portion to be the master substrate 11, then the center hole for the upper blade 45a and the outer peripheral edge 45b is original plate 11' original plate 11 in contact with The master substrate 11 is punched out from the original plate 11 ′. At this time, the knockout plate 46 presses the original plate 11 ′ by the force of the compression coil spring 48.

  Through the above punching process, a master substrate 11 having the uneven pattern P on the surface of the original plate 11 'shown in FIG. 4 (e) of the master substrate 11 shown in FIG. 4 (d) are formed. In this punching process, since punching on the back side from the front surface side of the concavo-convex pattern P is formed in the original plate 11 'of the master substrate 11, burr BA punching portion occurs on the back side of the master substrate 11, the surface side plastic deformation sagging portion DA is formed. Further, since the clearance C between the upper blade and the lower blade is adjusted to an appropriate value and the punching stroke is also set appropriately, the burrs BA at the punched portion are also small.

  In the present invention, after punching the original plate 11 ′, the back surface of the punched master substrate 11 is polished. FIG. 7 shows a polishing apparatus. In the polishing apparatus 60, a polishing grindstone 62 is attached to the upper surface of a rotating platen 61.

  Opposite to the grinding wheel 62, a work holder 63 is supported so as to be able to rotate and move up and down. Master substrate 11 after punching is magnetic clamp the workpiece holder 63 with the protective tape side, the rear surface is polished is pressed against the grindstone 62, flattening the entire back surface is achieved with burrs BA is polished.

The polishing grindstone 62 is a fixed abrasive made of silicon carbide (SiC) or alumina (Al ₂ O ₃ ), and particle sizes # 1200 and # 2500 are used. The polishing conditions in this polishing step are dry polishing in which the rotation speed of the platen 61 is 65 rpm, the rotation speed of the work holder 63 (that is, the rotation speed of the master substrate 11) is 95 rpm, and the polishing pressure is 5 to 15 PSi. The grinding wheel 62 is roughly ground for 25 seconds, and then the grinding wheel 62 having a particle size of # 2500 is finished for 25 seconds and finished in two steps.

  The master substrate 11 from which the back surface burrs BA have been removed and the entire surface has been flattened by this polishing process is then peeled off from the protective sheet applied to the concave / convex pattern P side, and then the magnetic layer 12 is formed on the concave / convex pattern P. It is. The magnetic layer 12 is formed by depositing a magnetic material by a vacuum film forming means such as a vacuum deposition method, a sputtering method, or an ion plating method, or a plating method or a coating method.

  As the magnetic material of the magnetic layer, Co, Co alloy (CoNi, CoNiZr, CoNbTaZr, etc.), Fe, Fe alloy (FeCo, FeCoNi, FeNiMo, FeAlSi, FeAl, FeTaN, etc.), Ni, Ni alloy (NiFe, etc.) are used. it can be used. In particular, FeCo and FeCoNi can be preferably used. The thickness of the magnetic layer 12 is preferably in the range of 50 to 500 nm, and more preferably in the range of 100 to 400 nm.

  A protective film such as diamond-like carbon (DLC) or sputtered carbon is preferably provided on the magnetic layer 12, and a lubricant layer may be further provided on the protective film. In this case, it is preferable to use a DLC film having a thickness of 3 to 30 nm and a lubricant layer as the protective film.

  Further, an adhesion enhancing layer such as Si may be provided between the magnetic layer and the protective film. The lubricant has an effect of improving deterioration of durability such as generation of scratches due to friction when correcting the deviation caused in the contact process with the slave disk 14. Through the above steps, the master disk 10 having no burrs BA on the back surface is manufactured.

  Next, a magnetic transfer method for transferring the uneven pattern P of the master disk 10 manufactured as described above to the slave disk 14 will be described. FIG. 8 is a perspective view of a main part of a magnetic transfer apparatus 20 for performing magnetic transfer using the master disk 10 according to the present invention.

  Slave surface of the slave disk 14 after the initial DC magnetization to be described later shown in FIG. 10 (a) when magnetic transfer (the magnetic recording surface) is brought into contact with the information bearing surface 13 of the master disk 10, a predetermined pressing force De be in close contact with each other. Then, with the slave disk 14 and the master disk 10 in close contact with each other, a magnetic field for transfer is applied by the magnetic field generating means 30 to transfer the concave / convex pattern P of the master disk 10 to the slave disk 14.

  Slave disk 14, a hard disk magnetic recording layer on one or both sides is formed a disk-shaped recording medium such as a flexible disk, before brought into close contact with the master disk 10, glide head, minute projections and surfaces due abrasive body A cleaning process (burnishing or the like) for removing adhering dust is performed as necessary.

  As the magnetic recording layer of the slave disk 14, a coating type magnetic recording layer, a plating type magnetic recording layer, or a metal thin film type magnetic recording layer can be adopted. Magnetic materials for the metal thin film type magnetic recording layer include Co, Co alloys (CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoNi, etc.), Fe, Fe alloys (FeCo, FePt, FeCoNi, etc.), Ni, Ni alloys (NiFe Etc.) can be used.

  These are preferable because they have a high magnetic flux density and have magnetic field anisotropy in the same direction as the magnetic field application direction (in-plane direction for in-plane recording), thereby enabling clear transfer. In order to provide the necessary magnetic anisotropy under the magnetic material (on the support side), it is preferable to provide a nonmagnetic underlayer. This underlayer needs to match the crystal structure and lattice constant to the magnetic layer 12. For that purpose, it is preferable to use Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru or the like.

  The magnetic transfer by the master disk 10 is performed when the master disk 10 is brought into close contact with one side of the slave disk 14 and the transfer is performed on one side of the slave disk 14. There are cases where simultaneous transfer is performed.

  Magnetic field generating means 30 for applying a transfer magnetic field is an electromagnet device 34, 34 the coil 33 to the core 32 is wound with a gap 31 extending in the radial direction of the slave disk 14 and master disk 10 which is tightly held within the upper and lower sides A transfer magnetic field having magnetic field lines G (see FIG. 9) parallel to the track direction is applied in the same direction in the upper and lower directions. FIG. 9 shows the relationship between the circumferential tracks 14A, 14A...

  When the magnetic field applied, while rotating integrally with the slave disk 14 and the master disk 10 is applying a transfer magnetic field by the magnetic field generating means 30, magnetically transferring a concavo-convex pattern P of the master disk 10 to the slave surface of the slave disk 14 to. It may be rotated move towards the magnetic field generating means in addition to this configuration.

  The transfer magnetic field does not have any magnetic field strength exceeding the maximum value in the optimum transfer magnetic field strength range (0.6 to 1.3 times the coercive force Hc of the slave disk 14) in any of the track directions. There are at least one portion having a magnetic field strength within the range in one track direction, and the magnetic field strength in the opposite track direction is less than the minimum value in the optimum transfer magnetic field strength range at any position in the track direction. A magnetic field having a certain magnetic field intensity distribution is generated in a part of the track direction.

  FIG. 10 is an explanatory diagram for explaining the basic steps of the magnetic transfer method using in-plane recording. First, as shown in FIG. 10A, initial magnetization (DC demagnetization) is applied to the slave disk 14 in advance by applying an initial magnetic field Hi in one direction in the track direction.

  Next, as shown in FIG. 10B, the recording surface (magnetic recording portion) of the slave disk 14 is brought into close contact with the information carrying surface 13 on which the concave / convex pattern P of the master disk 10 is formed. Magnetic transfer is performed by applying a transfer magnetic field Hd in the direction opposite to the initial magnetic field Hi in the track direction. The transfer magnetic field Hd is sucked into the convex magnetic layer 12 of the concavo-convex pattern P so that the magnetization of this portion is not reversed and the magnetic field of the other portion is reversed. As a result, as shown in FIG. The concave / convex pattern P of the master disk 10 is magnetically transferred and recorded on the magnetic recording surface 14.

  In such magnetic transfer, it is important for the high-precision transfer that the slave disk 14 and the master disk 10 are brought into close contact with each other. However, the burr BA manufactured by the method for manufacturing a master disk for magnetic transfer according to the present invention is used. By using a small master disk 10, good adhesion can be achieved, and a high-quality magnetic recording medium 14 can be obtained.

  In the above-described embodiment, in the punching process of the original plate 11 ′, the upper die 45 is moved and punched with respect to the fixed original plate 11 ′. However, the present invention is not limited thereto, and the original plate 11 is not limited thereto. 'May move toward the upper die 45, and if the die and the original plate 11 ′ are relatively moved and punched from the front surface side (uneven pattern P side) of the original plate 11 ′ toward the back surface, Various modifications can be applied.

Partial perspective view of master disk Sectional view taken along line A-A of FIG. 1 Plan view of the master substrate Process drawing showing master disk manufacturing method Sectional drawing which shows the punching tool used with the manufacturing method of the master disk for magnetic transfer of this invention Conceptual diagram explaining the occurrence of burrs Front view illustrating a polishing apparatus Perspective view of main part of magnetic transfer device Plan view illustrating the method of applying magnetic field for transfer Process diagram showing the basic steps of the magnetic transfer method

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Master disk (master disk for magnetic transfer), 11 ... Master board | substrate, 11 '... Original board, 12 ... Magnetic layer, 14 ... Slave disk (magnetic recording medium), 17 ... Master disk, 18 ... Metal disk, 40 ... Punching tool 42 ... Lower die (fixed blade), 45 ... Upper die (moving blade), BA ... Burr, C ... Clearance, P · P '... Uneven pattern

Claims (5)

A master disk on which a concave and convex pattern corresponding to transfer information is formed is laminated with a metal disk having a predetermined thickness by electroforming or the like, and the metal disk peeled off from the master disk is punched into a predetermined shape to form a master substrate. In the method of manufacturing a master disk for magnetic transfer in which a magnetic layer is formed on the uneven pattern of the substrate,
The punching process is
Using a punching tool consisting of a fixed blade and a moving blade,
The metal plate is punched into a predetermined shape by moving the movable blade or the fixed blade relative to the metal plate from the front side to the back side where the concave and convex pattern of the metal plate is formed. A method for manufacturing a magnetic transfer master disk.   2. The magnetic transfer master disk according to claim 1, wherein a size of a burr formed on a back surface of the master substrate at the time of punching is adjusted by adjusting a clearance between the fixed blade and the movable blade. Production method.   Relative punching stroke with respect to the metal disk of the moving blades or the stationary blades, from the position where the movable blade or the fixed blade is in contact with the surface of the metal plate to a position where the metal plate is punched out into a predetermined shape 3. The method for manufacturing a master disk for magnetic transfer according to claim 1, wherein the punching stroke is set such that a distance plus an additional distance is set to a predetermined value.   The stamped claims 1, 2, or method of producing a magnetic transfer master disk according to any one of the three characterized by polishing the back surface of the master substrate.   The preformat information is magnetically transferred using the magnetic transfer master disk manufactured by the magnetic transfer master disk manufacturing method according to any one of claims 1 to 4. magnetic recording media.

Images