JPS63313324A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To unify the crystal orientation directions of deposited magnetic particles and to improve the squareness ratio and magnetic characteristics of a magnetic recording medium by immersing a substrate to be treated in an electroless plating bath and alternately and repeatedly executing the deposition of magnetic particles on the substrate surface and the formation of the leak magnetic field on the magnetic particle layer. CONSTITUTION:A disk substrate 11 which is the substrate to be treated is immersed in the plating bath 12 by positioning the treating surface thereof in a perpendicular direction. The deposition of the magnetic Co-P particles arises on the surface of the substrate 11, which surface is immersed in the plating bath, if the switch of an AC power supply 16 is turned on while the substrate 11 is rotated. On the other hand, the deposited magnetic Co-P particle layer deposited on the surface of the substrate 11, which surfaces faces an AC magnetic field generating head 13, is magnetized. Since the magnetic field direction of the head 13 is changed to the circumferential direction of the substrate 11 in conformity with the AC cycles, the leak magnetic field is generated on the magnetic Co-P particle layer on the substrate 11 surface and the crystal orientation directions of the freshly deposited magnetic particles are eventually unified in the circumferential direction of the substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing magnetic recording media such as hard disks and floppy disks.

[Prior Art] Fig. 5 shows the cross-sectional structure of a conventionally known plated magnetic disk, and Fig. 6 shows its manufacturing flow sheet.To explain the manufacturing method of this magnetic disk, we will begin by Zn displacement plating is applied to the surface of the AJl substrate 1, and then N1-P nonmagnetic particles are precipitated in N1-P electroless plating to form a nonmagnetic underlayer 2. Then, this substrate material is immersed in a Co--P electroless plating bath, and Co--P magnetic particles are precipitated on the N1-P nonmagnetic underlayer 2 in this plating bath to form a magnetic particle layer 3. Finally, the Co--P magnetic particle layer 3 is coated with a protective film 4 and further coated with an oil slip film 5 to be manufactured into a product.

[Problems to be Solved by the Invention] However, according to the magnetic disk manufactured in this manner, in the Co-P magnetic particle layer 3, the crystal orientation (0, 0, 2> direction) of the Co crystal grains is Figures 7 and 8 show the stacked state of the crystal grains, and in the initial stage of precipitation of Co-P magnetic grains, the crystal orientation of the CO crystal grains is (0,0,
The crystal orientation (0° 0.2
) directions tended to be aligned in the in-plane direction, but the in-plane orientations still varied. For this reason, when manufactured as a product, the squareness ratio (the ratio of the amount of residual magnetization to the amount of saturation magnetization) is low, and the magnetic properties when reading information recorded on the surface of the magnetic disk are poor.

[Purpose of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to ensure that the crystal orientation (0, 0, 2) direction of the magnetic particles is in an orderly state in the magnetic particle layer. The objective is to manufacture a magnetic recording medium that is laminated with As a result, the squareness ratio of the magnetic recording medium is improved, and the magnetic properties are improved.

[Means for Solving the Problems] To achieve this object, the present invention immerses a substrate to be processed in an electroless plating bath, deposits magnetic particles on the surface of the substrate, and deposits magnetic particles on the surface of the substrate. After precipitating a small amount of magnetic particles, an alternating magnetic field is applied to the surface of the substrate to magnetize the magnetic particle layer, and a leakage magnetic field is generated on the magnetic particle layer. The gist is that these are repeated alternately.

[Example] An example of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an electroless plating apparatus for depositing Co--P magnetic particles embodying the present invention. The composition of the plating bath is as shown in the following table.

Co50+・711□00.05iol/NoNapH,
02-11z0 0.19mol#7 to NaC411406・4tl□0 0.7
1io1/J(NH4)2SO40,611o1#'a
ll adjustment (NaOll) ptll.

Bath temperature: 80° C. In this apparatus, a disk substrate 11, which is a substrate to be processed, is immersed in the plating plate with its processing surface oriented vertically. Then, Co--P magnetic particles are deposited on the surface of the disk substrate 11 while rotating within the surface of the substrate. According to the present invention, as shown in the figure, the disk substrate 11 is rotated with about half of the disk substrate 11 exposed above the surface of the plating bath. and the substrate 11
AC magnetic field generating heads 13 and 13 are arranged to face each other in the radial direction of both sides protruding from the plating bath.

The AC magnetic field generating head 13 has a magnetic iron core (yoke) 14
The excitation coil 15 is connected to an AC power source 16.

According to the present invention, the AC power source 16 is turned on while the disk substrate 11 is rotating in the direction of the arrow in FIG. Then, Co--P magnetic particles are deposited on the surface of the substrate 11 immersed in the plating layer, while on the surface of the crystal plate 11 facing the AC magnetic field generating head 13, the substrate 11 is immersed in the plating layer.
The Co--P magnetic particle layer deposited on the surface is magnetized.

At this time, as shown in FIG. 2, since the direction of the magnetic field of the head 13 is switched in the circumferential direction of the substrate 11 at short intervals in accordance with the AC cycle, as shown in FIG.
A leakage magnetic field is generated on the Co--P magnetic particle layer on the substrate 11 surface. Therefore, when the leakage magnetic field generation surface of the substrate 11 is immersed in the plating layer as the substrate rotates, newly precipitated Co-
The crystal orientation (0, 0, 2> direction of the P magnetic particles is aligned with the most stable direction in terms of energy, that is, the circumferential direction of the substrate 11. By continuing to rotate the substrate 11 in this way, the crystal orientation (0, 0, 2> direction) on the magnetic particle layer Generating a leakage magnetic field and depositing magnetic particles on the surface are repeated to obtain an orderly laminated magnetic particle layer in which the crystal orientation (0, 0, 2) of the magnetic particles is aligned.

Next, when comparing the squareness ratio of the magnetic disk obtained in this way with a conventional product, it is found that when the thickness of the magnetic particle layer is 80OA, the squareness ratio of the conventional method was about 0°6. In the method of the present invention, the squareness ratio was 0.8 to 0.9, which was a good value.

It should be noted that the present invention is not limited to circular substrates as in the above-mentioned embodiments, but the point is that magnetic particles are deposited on the substrate surface while repeating relative movement of the AC magnetic field generating head, and at that time, crystals of the deposited magnetic particles are formed. Since the purpose is to align the azimuths, it can also be applied to rectangular substrates such as magnetic cards.

In addition, the composition of the electroless plating bath is Co as shown in the above example.
Of course, the magnetic film is not limited to the -P type, and the magnetic film may be formed by electroplating, sputtering, or the like.

[Effects of the Invention] As described above with respect to the embodiments, according to the present invention,
Magnetic recording media with excellent squareness ratio! ! ! It has great practical benefits, such as improved magnetic properties.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the general configuration of an electroless plating apparatus for realizing the present invention, FIGS. 2(a) and (b) are explanatory diagrams of the magnetic field generated by the AC magnetic field generating head, and FIG. 3 is a deposition 4 is a plan view thereof, FIG. 5 is a cross-sectional configuration diagram of a conventional general magnetic disk, FIG. 6 is a manufacturing flow sheet thereof, and FIG. FIG. 8 is a diagram illustrating the crystal orientation (0,0,2) direction of precipitated magnetic particles in a conventional magnetic disk. 11: Disk substrate, 12: Plating bath, 13: AC magnetic field generating head Fig. 2 Fig. 5 Fig. 3 Fig. 4 Fig. 8 Fig. 7

Claims (1)

[Claims] A method of precipitating magnetic particles on the surface of a substrate, in which a small amount of magnetic particles are precipitated on the surface of the substrate, and an alternating current magnetic field is applied to the substrate surface to magnetize the magnetic particle layer. A method for manufacturing a magnetic recording medium, characterized in that a leakage magnetic field is generated, and the formation of the leakage magnetic field and the precipitation of magnetic particles are alternately repeated.