JP2704615B2 - Magnetic recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording apparatus using a so-called hard type magnetic disk and a floating magnetic head. Prior art and its problems The magnetic recording medium used in a magnetic disk drive is generally called a magnetic disk or a disk medium, and its basic structure has a doughnut-shaped substrate and magnetic layers usually provided on both surfaces thereof. ing. There are two types of substrate materials of such a recording medium, for example, a hard material such as an aluminum alloy and a plastic material such as Mylar which is the same as a magnetic tape medium. Generally, the former is called a hard type magnetic disk, and the latter is called a flexible disk. In. By the way, a hard magnetic disk uses a floating magnetic head, and a contact / contact of this head is used.
A large impact is applied at the time of start / stop, and durability, abrasion resistance, head suction, and the like against mechanical contact with the magnetic head have become problems. Heretofore, it has been considered that these problems are mainly caused by various physical properties of the medium surface, and various proposals for providing a protective film as an uppermost layer with the medium have been made. However, for issues such as durability, not only focusing on the improvement of the medium surface, but also taking into account the correlation with various physical properties of the floating magnetic head used, the optimum It is necessary to set the recording device. II Object of the Invention It is an object of the present invention to provide a magnetic recording apparatus having excellent durability and the like of a medium and a flying surface of a head. III Disclosure of the Invention Such an object is achieved by the present invention described below. That is, the present invention provides a magnetic recording medium having a magnetic layer on a non-magnetic base material, and a magnetic recording apparatus that performs recording and reproduction using a floating magnetic head, wherein the Vickers hardness Hvs of the base material surface and the floating magnetic head Difference from the Vickers hardness Hvh of the air bearing surface △ Hv = (Hvs−Hv
h) / Hvh × 100 is within ± 20%. IV Specific Configuration of the Invention The present invention relates to a magnetic recording device using a magnetic recording medium and a floating magnetic head, and the specific configuration of these will be described below in detail. The magnetic recording medium used in the present invention has a magnetic layer such as a metal thin film on a non-magnetic substrate. Various non-magnetic substrates can be used as the non-magnetic substrate. Examples of the material include various non-magnetic metal materials such as aluminum, SiC, Al ₂ O ₃ , ZrO ₂ , Si ₃ N ₄ , Y ₂ O
_3, a mixed material such as or their calcium titanate or a solid solution, oxides, carbides, silicides, nitrides and various non-magnetic ceramic material, various kinds of glass materials, various plastic materials, and other disk-shaped to allow high-precision processing Is used. Further, various known non-magnetic base layers provided on the surface of such a non-magnetic substrate by CVD, sputtering, plating or the like can also be used as the non-magnetic substrate of the present invention.
Various heat treatments can be applied to these nonmagnetic underlayers. Vickers hardness Hvs of the surface of non-magnetic base material
Is the hardness difference (%) with respect to the Vickers hardness Hvh of the floating surface of the floating magnetic head described later. Is within ± 20%. If this value ΔHv exceeds + 20%, the hardness as a medium becomes greater than the limit of the head flying surface, and the durability of the head flying surface deteriorates. On the other hand, if this value is less than -20%, the durability of the medium will be worse. In this case, the Vickers hardness Hvs of the base material surface is the Vickers hardness of the base material surface before the formation of the magnetic layer or various intermediate layers. The Vickers hardness of the substrate surface can be measured by exposing the substrate surface by subjecting the medium to, for example, acid treatment or polishing treatment. In the present invention, the Vickers hardness Hvs of the base material having the underlayer surface if necessary, the Vickers hardness Hvh of the head floating surface
Adjust for. In this case, the head floating surface refers to a surface that comes into sliding contact with the medium surface until various floating magnetic heads described later float on the medium surface. For example, in the case of a monolithic head typified by a Winchester type head, the transducer portion becomes the air bearing surface. When the head flying surface is formed of a plurality of materials, the hardness of the same material portion occupying 60% or more of the flying surface is defined as the hardness of the flying surface. Therefore, a so-called composite head in which a transducer is fixed to a structure such as a ceramic (so-called slider) with glass or the like, or a thin film element made by a process similar to the semiconductor manufacturing technology is attached to a structure such as a ceramic (so-called slider). In the case of a thin-film head or the like, the flying surface is not limited to the slider portion but can also include a transducer portion. In these cases, the slider occupies more than 60% of the flying surface. The hardness of the air bearing surface is defined as Hvh. As the material of the air bearing surface of such a magnetic head, 1)
For example, ferrite of Mn-Zn system, Ni-Zn system, etc., 2) CaTiO ₃
And 3) Al ₂ O ₃ —TiC type and the like, and their Vickers hardness Hvh is 1) 400 to 800, 2) 800 to
1500, 3) about 1500-2500. Further, as the material and hardness of the base material used, in the range of Vickers hardness Hvs 400 to 800, for example, there is a Ni-P base layer formed on an aluminum substrate, and the like.
Within the range of 0 to 1500, for example, zirconia, yttria, glass, alumina, various ceramics and various glasses such as aluminum nitride, and within the range of 1500 to 2500, alumina, silicon nitride, titanium nitride and the like. is there. In addition, Vickers hardness Hv is a method of indicating the hardness of the material, using a square pyramid diamond with a vertical angle of 136 °,
It is indicated by a value obtained by dividing the load by the surface area of the hollow after unloading. JIS for Vickers hardness is JIS Z2244-1976, Z
2251-1980, BT7725-1976, and B7734. The non-magnetic substrate as described above may be the non-magnetic substrate itself, or may be composed of a substrate and an underlayer provided thereon. This is because the value of Hvs can be controlled to a desired value when the underlayer is provided. As the base layer formed on the substrate, films of various materials can be used. By the way, as described above, the Hvs of the substrate surface is 400 to 800 when ferrite, particularly Mn-Zn ferrite is used as the head floating surface, and particularly preferably 500 to 800. When such a Mn-Zn ferrite head is used, Ni-P, Ni-Cu-P, Ni-WP, etc.
-P-based metal films are preferred. It is preferable that these films, especially Ni-P type metal films, be formed by liquid layer plating, particularly electroless plating.
According to the electroless plating method, a film having a very uniform thickness can be formed, and mechanical rigidity, hardness and workability can be improved. And Hvs can be adjusted easily. The following is preferable as the composition of the Ni-P base layer. (NixCuy) _A P _B (NixWy) _A P _{B In} these cases, x: y = 100: 10-10: 90 and A: B = 97: 3-85: 15. To briefly describe an example of a process of forming an underlayer by electroless plating, first, alkaline degreasing and acidic degreasing are performed. Thereafter, the zincate treatment was repeated several times, and the surface was adjusted with sodium bicarbonate or the like, and then pH 4.
About 80-95 ° C in a nickel plating bath of 0-6.0, about 0.5-
The plating may be performed for 3 hours. These plating processes are described in, for example, Japanese Patent Publication No. 48-18842 and Japanese Patent Publication No. 50-1438. The thickness of such an underlayer is 3 to 50 μm, particularly 5 to 25 μm.
m is preferred. Normally, the Vickers hardness Hvs of the Ni-P base layer is 400 or more, particularly 400 to 50, before heat treatment after film formation described below.
It is 0. It is preferable to perform a heat treatment after the formation of the underlayer such as the Ni-P system. This is because the hardness can be set and adjusted to a desired value by the heat treatment. Changes in hardness and maximum magnetic flux density due to this heat treatment are shown in FIGS. 1 and 2, respectively. 1 and 2 show the Vickers hardness Hv and the maximum magnetic flux density B _{m of a} NiP (Ni: P = 87: 13) plating film used as the composition of the underlayer, respectively, when the plating film is formed to a thickness of 20 μm.
4 is a graph showing the relationship between the temperature and the heat treatment temperature. According to this, Hv gradually increases as the temperature rises up to a processing temperature of around 280 ° C., but Hv sharply increases at a processing temperature of around 300 ° C. And even if it exceeds 300 ° C,
Hv is still increasing, though gradually. Therefore, in order to simply increase Hv, it is advantageous to perform heat treatment at a temperature near 300 ° C. or higher. However, when the processing temperature is too high, as shown in FIG. 2, the magnetic properties of NiP start, which causes a disadvantage that it is not practically preferable. In this case, B _m is 10
If it is more than G, especially more than 500G, it is not suitable for practical use. Therefore, in the case of the Ni-P film, the heat treatment temperature is 200 to 295.
C., especially 200 to 280.degree. C., and the treatment time is preferably about 30 minutes to 3 hours. If this temperature exceeds 295 ° C., the underlayer is magnetized as described above, and the surface properties after precision polishing are deteriorated, which is not practically preferable. If the temperature is lower than 200 ° C., the hardness does not increase more than a predetermined value, and the mechanical durability and the like are lowered. At the time of heat treatment, a clean oven or the like may be used. By such a heat treatment, the Vickers hardness of the surface of the NiP-based underlayer is 500 to 1100, particularly 500 to 800, more preferably 550.
750Hv can be adjusted within ± 20% with respect to the Vickers hardness of the head floating surface as described above. Examples of the substrate material for forming such a Ni-P-based film underlayer include metals, glass, ceramics, engineering plastics, and the like. Among these, mechanical rigidity, workability, and the like are preferable. In this case, it is preferable to use aluminum, an aluminum alloy, or the like, which can easily form a base layer. In addition to the Ni-P based film, the desired Hvs
Various types can be used according to the conditions. The base material of the present invention is formed from the substrate itself, or a base layer is provided on the substrate, and both are integrated to form the base material. The thickness of the substrate is, for example, 1.2 to 1.9 mm, and the shape is usually a disk shape. It is preferable to provide an uneven portion on the surface of the nonmagnetic substrate. In order to provide the irregularities, for example, an abrasive is applied while rotating a disk-shaped substrate on which an underlayer is provided, and, for example, irregular grooves are provided concentrically on the surface of the underlayer. The uneven portions may be provided, for example, randomly on the base layer. The surface roughness Ra of the base material is preferably 0.001 to 0.05 μm, more preferably 0.005 to 0.02 μm. By providing such an uneven portion, the adsorption characteristics and the durability are improved. Further, on such a substrate, usually Co or Co and Ni, C
A magnetic layer of a metal thin film mainly composed of at least one of r and P is provided. As specific examples of the composition of this, Co-Ni, Co-Ni-
Cr, Co-Cr, Co-Ni-P, Co-Zn-P, Co-Ni-Mn-Re
-P and the like. Among these, Co-Ni, Co-Ni-C
r, Co-Cr, Co-Ni-P and the like are preferable, and the preferable composition ratio of these alloys is, by weight ratio, Co: Ni = 1: 1 to 9: 1, _x in (Co _x Ni _y ) _A Cr _B : y = 1: 1~9: 1 , A: B = 99.9: 0.1~75: 25, Co: Cr = 7: 3~9: 1, in _{(Co x Ni y) A P} B, x: y = 1: 0 to 1: 9, A: B = 99.9: 0.1 to 85:15. Outside these ranges, the recording characteristics deteriorate. The magnetic layer of such a metal thin film can be formed by various plating methods of a gas phase or a liquid phase. Among them, a sputtering method, which is one of the gas phase methods, is particularly preferable. By using the sputtering method, a magnetic layer having good magnetic properties can be obtained. The sputtering method can be further roughly classified into a plasma method and an ion beam method depending on a region where the work is performed. In a sputtering method by a plasma method, an abnormal glow discharge is generated in an inert gas atmosphere such as Ar, and a target (evaporation material) is sputtered by Ar ions.
It is deposited on the adherend. Either DC sputtering for applying a DC voltage of several KV to the target or RF sputtering for applying a high frequency power of several hundreds to several KW may be used. In addition to the multi-polarization from two-pole to three-pole and four-pole sputtering equipment, a perpendicular electromagnetic field is applied to give cycloidal motion similar to the magnetron of electrons in the plasma, creating high-density plasma and lowering the applied voltage, May be used for the magnetron sputtering. In the ion beam method, Ar or the like is ionized and extracted using an appropriate ion source, extracted as an ion beam toward the high vacuum side by a negative high voltage applied to the electrode, and the target material sputtered by irradiating the target surface with, for example, a coating. Deposit on the body. Further, the kinetic energy of the adhered particles in the sputtering method is about several eV to 100 eV, for example, that of the vapor deposition method (about 0.1 eV
~ 1 eV). In the present invention, as the material of the target, an alloy or the like corresponding to the composition of the target magnetic layer of the metal thin film may be used. By the way, the composition of the magnetic layer of the metal thin film is changed to CoP or CoNiP.
In this case, the layer may be formed by a liquid phase plating method, particularly, an electroless plating method. The magnetic layer shows good magnetic properties as in the above-mentioned sputtering method. Various known plating bath compositions and plating conditions used for electroless plating can be applied.For example, those described in Japanese Patent Publication No. 54-9136, Japanese Patent Publication No. 55-14865, etc. Both can be used. The thickness of the magnetic layer of the metal thin film as described above is 200 to 5
000Å, especially 500-1000Å is preferred. When the magnetic layer of such a metal thin film is formed by the sputtering method as described above, it is preferable to provide a non-magnetic metal intermediate layer between the base material, preferably, the underlayer and the magnetic layer. By providing this non-magnetic metal intermediate layer, the magnetic properties of the medium are improved, and the reliability of the recording properties can be improved. The nonmagnetic metal intermediate layer is usually most preferably formed of Cr, but the Cr content may be 99 wt% or more. The intermediate layer can be formed by various known vapor-phase film forming methods, but it is generally preferable to form the intermediate layer by a sputtering method as in the case of the magnetic layer of the metal thin film described above. The thickness of such a nonmagnetic metal intermediate layer should be appropriately determined depending on the type of the metal thin film magnetic layer to be used, but is usually about 500 to 4000 °. Further, a non-magnetic metal protective film is preferably provided on the magnetic layer. The composition and the method of forming the protective film may be the same as those of the non-magnetic metal intermediate layer. The thickness of such a nonmagnetic metal protective film is preferably 30 to 300 °, particularly preferably 50 to 200 °. Further, it is preferable that a protective layer and a top coat layer are sequentially laminated on the nonmagnetic metal protective film. The protective layer is preferably composed of C alone as a composition, but may also contain other elements in an amount of less than 5 wt%. Such a protective layer can be formed by various vapor-phase film forming methods such as a sputtering method, an ion plating method, a vapor deposition method, and a CVD method. Among them, the sputtering method is particularly preferable. In this case, the formed film becomes extremely dense, and has an effect excellent in durability and weather resistance. The thickness of the protective layer thus formed is preferably from 10 to 800, particularly preferably from 100 to 400. The topcoat layer preferably contains a fluorine compound, and may be formed by a coating method or by any of various vapor deposition methods including a plasma polymerization film. The thickness is about 3 to 300 °. However, it is not limited to the above configuration,
Various embodiments in consideration of the composition are also conceivable. For example, a plasma polymerized film may be newly formed between various laminations or may be formed by changing an arbitrary one layer. The surface between the layers can be subjected to plasma treatment. These are particularly effective in increasing the adhesive strength between the media laminations and improving the durability. The magnetic recording medium as described above may be a so-called single-sided recording medium in which the magnetic layer is provided only on one side of the substrate, or a so-called double-sided recording medium in which magnetic layers are provided on both sides of the substrate. Incidentally, the medium used in the present invention may have a coating type magnetic layer instead of the above-described medium having a thin film type magnetic layer. In this case, the magnetic layer contains a magnetic powder, a binder, and, if necessary, additives such as an abrasive. However, in the case of the coating type in which the thickness of the magnetic layer is relatively large, the magnetic layer is hardly affected by the substrate due to the cushioning effect of the magnetic layer, whereas in the case of the metal thin film type magnetic layer, The present invention is particularly effective for a metal thin film type magnetic layer since the Vickers hardness of the substrate directly affects the Vickers hardness. In the recording apparatus of the present invention, the above-described magnetic recording medium and the following floating magnetic head are used simultaneously. The flying magnetic head has been developed to realize a large storage capacity and a high data transfer rate. And this is floating while maintaining a predetermined clearance on the medium by the dynamic pressure generated by the viscosity of air when this and the magnetic recording medium move relatively at high speed, and in this state, Write information on the medium,
Alternatively, it acts to read information from the medium. Examples of the type of such a magnetic head include the well-known Winchester type, composite type, and thin film type described above, but any type may be used in the present invention, and there is no particular limitation. To restate, a Winchester type head is a typical one in which a portion for generating the dynamic pressure, that is, a floating surface is formed in a part with the transducer. The composite type head is a structure in which a transducer is fixed to a structure such as ceramic having an air bearing surface with glass or the like.The thin film type head converts a thin film element made by a process similar to semiconductor manufacturing technology into a ceramic structure. It is attached. When the magnetic recording medium, especially the disk medium, is stationary, the head is pressed against the disk surface by the spring force, and when the disk starts to rotate, dynamic pressure is generated, and the magnetic head flies with the spring force. The so-called CSS method is usually adopted. The material of the air bearing surface of these magnetic heads is as described above. This portion is a flat surface that faces substantially in parallel with the surface of the recording medium at the time of recording / reproduction with a small gap therebetween, and is in sliding contact with the front surface of the disk before floating. The Hvh of these air bearing surfaces is 400 to 2500, particularly 600 to 2500. V According to the present invention, the hardness of the non-magnetic substrate is set so as to have a predetermined relationship with the hardness of the air bearing surface of the floating magnetic head. When used for recording and reproduction, the durability and the like of the medium are significantly improved. Further, the durability of the air bearing surface of the magnetic head is also improved. VI Specific Examples of the Invention Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention. [Example 1] Substrates 1 to 11 having a diameter of 3.5 "and a thickness of 1.9 mm and made of various materials shown below were used as medium substrates: Substrate 1 Kobe Steel CD-1 Grade 3.5 ″ Aluminum disc, diamond-turn product. Substrate 2 Kobe Steel CE-1 grade 3.5 "aluminum disk, 20μm NiP plating on a grind product (Ni / P
= 88/12 (wt%)). The plating was performed by electroless plating under the following process and manufacturing conditions. Use this with Speed Fam 9B-5P lapping machine, Fujimi polishing polishing liquid, Mediball N-08 (50% diluting liquid)
Was polished for 10 minutes under a load of 100 g, and polished to 5 μm. Substrate 3 Before polishing of the substrate 2, a heat treatment was performed in the air at 200 ° C. for 2 hours. Hereinafter, polishing was performed in the same manner. Substrate 4 Before the substrate 2 was polished, a heat treatment was performed in the air at 275 ° C. for 2 hours. Substrate 5 Before the polishing of the substrate 2, a heat treatment was performed in the air at 290 ° C. for 2 hours. Substrate 6 Y ₂ O ₃ -ZrO ₂ , 2.2 mol% yttria, 1500 ° C. in air
After firing for an hour, the substrate surface was polished with 0.1 μm diamond. Substrate 7 On the aluminosilicate glass, Cr ₃ C _{2 of} 50 ° was provided by CVD. Substrate 8 The composition of the substrate was blended so that Al ₂ O ₃ / SiO ₂ / MgO / CaO = 96/2/1/1 and baked at 1450 ° C. for 1 hour in the atmosphere. Substrate 9 Raw materials for the substrate composition were blended so that Al ₂ O ₃ /MgO=99.5/0.5, and fired at 1600 ° C. for 1 hour in the atmosphere. Substrate 10 Al / Ti = 6/4 CeO ₂ 0.5% Al ₂ O ₃ -TiC at 1700 ° C, 300 in Ar
It was fired at kg / cm ^{2 for} 1 hour. Substrate 11 The surface of the SiC substrate was coated by CVD so that the SiC had a thickness of 50 mm. The surfaces of the substrates 7 to 11 were polished similarly to the case of the substrate 6. Next, each of these substrates was cleaned in the following steps using a disk substrate cleaning apparatus (manufactured by Speed Fam Clean System Co., Ltd.). <Cleaning process> 1. Neutral cleaning solution, immersion, ultrasonic 2. Ultra pure water, scrub 3. Ultra pure water, scrub 4. Ultra pure water, immersion, Ultrasonic 5. Ultra pure water, immersion 6. Freon / Ethanol mixed solution, immersion, ultrasonic wave 7. Freon / ethanol mixed solution, immersion 8. Freon / ethanol, steam (→ drying) After such a washing process, irregularities were provided on the surface of each substrate as follows. (Hereinafter, referred to as a texturing step). That is, using a tape polishing machine (manufactured by Tomoe Techno Co., Ltd.), concentric irregular grooves were formed on the substrate surface while rotating the substrate. The process conditions were polishing tape # 4000, contact pressure 1.2kg / cm ² ,
The oscillation was set to 50 times / minute, and the number of work rotation was set to 150 times / minute. Ra after texturing process is 0.010 for substrates 1-5
μm, and 0.015 μm for the substrates 6 to 11. Thereafter, after performing the above-described cleaning, a nonmagnetic metal intermediate layer of Cr was formed to a thickness of 2000 mm by sputtering. Layering conditions were Ar pressure, 2.0 Pa, and EC8KW. Before the formation of the intermediate layer, etching was performed under the conditions of an Ar gas pressure of 0.2 Pa and RF of 400 W. Thereafter, various metal thin-film magnetic layers as described below were successively provided thereon. When the magnetic layer is formed by the electroless plating method, the above-described etching process is not performed,
Moreover, no Cr nonmagnetic metal intermediate layer was provided. <Formation of Metal Thin Film Magnetic Layer> A magnetic layer No. 1 CoNi magnetic layer was formed by a sputtering method. The deposition conditions were an Ar gas pressure of 2.0 Pa and a DC of 8 KW. CoNi composition weight ratio is Co / N
i = 80/20 and the film thickness was 600 °. Magnetic Layer A No.2 CoNiCr magnetic layer was formed by a sputtering method. The deposition conditions were an Ar gas pressure of 0.8 Pa and a DC of 8 KW. The CoNiCr composition weight ratio was 62.5: 30: 7.5, and the film thickness was 600 °. Magnetic Layer No. 3 A CoCr magnetic layer was formed by a sputtering method. The deposition conditions were an Ar gas pressure of 2.0 Pa and a DC of 8 KW. The composition weight ratio of CoCr was Co / Cr = 87/13, and the film thickness was 1000 °. Magnetic Layer No. 4 A CoNiP magnetic layer was formed using an electroless plating method. CoN
The composition weight ratio of iP was Co: Ni: P = 6: 4: 1, and the film thickness was 1000 °. The electroless plating process and manufacturing conditions were as follows. Specific magnetic metal protective films made of Cr were formed on the various magnetic layers thus formed. The film was formed by a sputtering method under the following conditions: an Ar gas pressure of 2.0 pa, DC 8 KW, and a film thickness of 20 Pa.
0 °. Further, on this protective film, a carbon protective film was provided to a thickness of 400 mm by a sputtering method. The sputtering conditions were an Ar gas pressure of 0.2 Pa and a DC of 8 KW. However, only when the material of the magnetic layer No. 4 among the magnetic layers Nos. 1 to 4 described above is used as the magnetic layer, an Ar gas pressure of 0.2 Pa RF400W
Etching was performed under the following conditions. The surface of the carbon protective film was subjected to plasma treatment. The plasma conditions were processing gas N ₂ , pressure 5 Pa, and power supply 13.56.
The frequency was set to MHz and the input power was set to 3KW. A top coat layer containing a lubricant as described below was formed thereon by spin coating. Spin coating conditions are 1000 rpm, 1
0 seconds. The film thickness was 100 °. <Topcoat layer composition> KRYTOX15 consisting of the following structural formula as a lubricant
7FS (Dupont) To Freon 113 (manufactured by Daikin Industries, Daiflon S-3)
In a solvent of 0.05% by weight
Was adjusted. In this manner, various magnetic disk samples shown in Table 1 below were produced, and the characteristics shown below were measured by combining these with the flying magnetic head shown in Table 1. The following three types of magnetic heads were used. Head A: Al ₂ O ₃ -TiC (Al / Ti = 7/3, others, Ba, Ti, Ce
= 2/1 / 0.5%) Head B: CaTiO ₃ type (Ti / Ca = 62.6 / 37.3) Head C: Mn-Zn ferrite type (Fe ₂ O ₃ / MnO / ZnO = 54/29/1)
6) (1) CSS durability A sample was set on a 3.5 ″ hard disk drive, and the number of contacts and start / stop was repeated, and the number of times until the intensity of the initially recorded signal output decreased to 90% was examined. (2) Measurement of Hvs, Hvh, ΔHV (%) Using Akashi MVK-1 type, load according to JISZ2251 and B7734
It was determined under the condition of 5 g. Table 1 shows the results. The effect of the present invention is clear from the results in Table 1. Example 2 A NiP plating underlayer was formed on the substrate 1 of Example 1 in the same manner as in Example 1. The composition of the underlayer was Ni: P = 87: 13 (weight ratio) and the thickness was 20 μm. Next, the surface of the underlayer was polished under the same conditions as in Example 1 and then washed as in Example 1. After such a cleaning step, a concave and convex portion was provided on the surface of the underlayer in the same manner as in Example 1, and Ra = 0.010 μm. Then, after performing the same washing | cleaning, the heat treatment of the underlayer was performed. That is, the conditions of the heat treatment were set to the processing temperatures 100 and 2
The underlayer having Vickers hardness values as shown in Table 2 was changed in the range of 00, 250, 285, and 300 ° C. (treatment time: all 2 hours). Thereafter, after the same washing as described above was performed, a medium was prepared in exactly the same manner as in Example 1. Table 2 shows the results when various monolithic Mn-Zn heads were used. The results of Table 2 clearly show the effects of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the Vickers hardness Hv of NiP and the heat treatment temperature. Figure 2 is a graph showing the relationship between the heat treatment temperature and the maximum magnetic flux density B _m of NiP.

Claims (1)

(57) [Claims] In a magnetic recording apparatus that performs recording and reproduction using a magnetic recording medium having a magnetic layer on a non-magnetic substrate and a floating magnetic head, the Vickers hardness Hvs of the substrate surface and the Vickers of the floating surface of the floating magnetic head Hardness difference ΔHv from hardness Hvh = (Hvs−Hv
h) A magnetic recording device characterized in that / Hvh × 100 is within ± 20%. 2. 2. The magnetic recording apparatus according to claim 1, wherein the non-magnetic substrate is a non-magnetic substrate or has a base layer on the non-magnetic substrate. 3. 2. The method according to claim 1, wherein the magnetic layer is a metal thin film magnetic layer.
Item 3. The magnetic recording device according to item 2 or 2. 4. 4. The magnetic recording apparatus according to claim 1, wherein the surface roughness Ra of the substrate surface is 0.001 to 0.05 [mu] m.