This patent document claims the benefit of Japanese Patent Application No. 2005-268153 filed on Sep. 15, 2005, which is hereby incorporated by reference.
The present embodiments relate to a soft magnetic film suitable for use in a magnetic pole portion of a recording head. Related Art
Generally, a magnetic material having a high saturated magnetic flux density Bs is used for a core layer of a thin film magnetic head. Accordingly, it is necessary to improve a record density by concentrating a magnetic flux in the vicinity of a gap of the core layer. For example, especially with an increase in recording density.
A soft magnetic film made of an alloy including Co and Fe as the magnetic material has been previously used. The soft magnetic film including Co and Fe and its manufacturing method are described in U.S. Unexamined Patent Application Publication No. 2003/0209295 [Patent Document 1].
Patent Document 1 teaches that acetic acid and boric acid are added into a plating bath when the soft magnetic film is formed so as to increase a saturated magnetic flux density of the soft magnetic film including Co and Fe.
However, when the acetic acid is added to the plating bath, a plating formation rate is substantially reduced. This is because the acetic acid is apt to form a complex with Co or Fe. Therefore, in order to increase the plating formation rate, it is necessary to greatly increase a density of Co ion or Fe ion in the plating bath. When the density of Co ion or Fe ion is increased, it expedites a degradation of plating facilities such as a filter or a plating tank used for circulating and filtering the plating bath, and it gives rise to a necessity of frequent facility substitution. Therefore, the manufacturing efficiency is decreased and the plating bath is degraded by creating a pause in circulation of the plating bath due to the frequent facility substitution or introducing dust at the time of substituting facilities.
Since the volatility of the acetic acid is large and a temporal change of density in the plating bath is large, the stability of the plating bath is decreased, which is not desired in view of working environments.
According to one exemplary embodiment, there is provided a soft magnetic film having a saturated magnetic flux density Bs of 2.39 T or more, in which only N and O are added as impurity elements to a CoFe plating film.
In this embodiment, the composition ratio of N may be in the range of about 0 at % to 4.2 at % when the total composition ratio of Co, Fe, N, and O is 100 at %.
The composition ratio of O may be in the range of about 0 at % to 10.8 at % when the total composition ratio of Co, Fe, N, and O is 100 at %.
According to another exemplary embodiment, there is provided a soft magnetic film, in which only N and O are added as impurity elements to a CoFe plating film, the composition ratio of N is in the range of about 0 at % to 4.2 at %, and the composition ratio of O is in the range of about 0 at % to 10.8 at %, when the total composition ratio of Co, Fe, N, and O is 100%.
The average crystal grain diameter may be about 0.1 μm or less. The composition ratio of Fe may be in the range of about 65.5 wt % to 74 wt % when the total composition ratio of Co and Fe is 100 at %.
In this embodiment, the composition ratio of Fe may be in the range of about 66 wt % to 73 wt %.
According to another embodiment, a recording head of an longitudinal magnetic recording type includes a lower core layer, an upper core layer, and a magnetic pole portion which is disposed between the lower core layer and the upper core layer to restrict a track width Tw on a surface facing a recording medium. The magnetic pole portion includes a lower magnetic pole layer connected to the lower core layer. An upper magnetic layer is connected to the upper core layer. A gap layer is located between the lower magnetic pole layer and the upper magnetic pole layer. The magnetic pole layer includes an upper magnetic pole layer connected to the upper core layer and a gap layer located between the upper magnetic pole layer and the lower core layer. The upper magnetic pole layer, the lower magnetic pole layer, or the upper magnetic pole layer and the lower magnetic pole layer are plated with the soft magnetic film.
Alternatively, according to another embodiment, there is provided a recording head of a perpendicular magnetic recording type, the recording head including a main magnetic pole layer. A track width Tw is restricted by a surface of the main magnetic pole layer that faces a recording medium and the main magnetic pole layer is plated with the soft magnetic film described above.
In the embodiment, the upper magnetic pole layer, the lower magnetic pole layer, and the main magnetic pole layer, which are plated with the soft magnetic film have a high saturate magnetic flux density Bs and have a fine crystal structure in which the soft magnetic film has an average crystal grain diameter is about 0.1 μm or less. Accordingly, it is possible to embody the recording head having high recording characteristic and excellent stability by planarizing the surfaces of the upper magnetic pole layer, the lower magnetic pole layer, and the main magnetic pole layer with high accuracy.
The track width Tw may be in the range of about 0.05 to 0.5 μm, the thickness of the upper magnetic pole layer may be in the range of about 0.1 to 5.0 μm. The thickness of the lower magnetic pole layer may be in the range of about 0.1 to 5.0 μm, and the lower magnetic pole layer, the upper magnetic pole layer, or the upper magnetic pole layer and the lower magnetic pole layer may have a plurality of crystals, in any portion of the track width Tw, as viewed in the thickness direction.
The track width Tw may be in the range of about 0.1 to 1.0 μm. The thickness of the main magnetic pole layer may be in the range of about 0.1 to 2.0 μm. The main magnetic pole layer may have a plurality of crystals in any portion of the track width Tw as viewed in the thickness direction.
A plurality of crystals may exist on any portion in the thickness direction as viewed in the track width Tw direction. Accordingly, the entire area of the upper magnetic pole layer, the lower magnetic pole layer, and the main magnetic pole layer, which are narrowed, can be formed dense with the fine crystals.
According to another embodiment, there is provided a method of manufacturing a soft magnetic film, wherein only N and O are added as impurity elements to a CoFe plating film by using a plating bath including only an aqueous solution of Fe salts, an aqueous solution of Co salts, sodium benzenesulfonate, and L-glutamic acid.
In this embodiment, sodium benzenesulfonate and L-glutamic acid are added to a plating bath. A plating bath can have an excellent stability since a temporal change of a plating bath composition can be reduced and a pH change of a plating bath can be suppressed without adding an acetic acid, boric acid and sodium chloride to a plating bath as in the past. Since only N and O are added as impurity elements to CoFe plating bath by the plating bath, a soft magnetic film with a saturated magnetic flux density Bs of 2.39 T or more can be efficiently plated.
The sodium benzenesulfonate added to the plating bath may be in the range of about 0.01 g/l to 0.10 g/l. The L-glutamic acid added to the plating bath may be in the range of about 0.1 g/l to 0.5 g/l.
According to another embodiment, a recording head of an longitudinal magnetic recording type comprises a lower core layer, an upper core layer, and a magnetic pole portion which is disposed between the lower core layer and the upper core layer to restrict a track width Tw on a surface facing a recording medium. The magnetic pole portion is formed of a lower magnetic pole layer connected to the lower core layer. An upper magnetic layer is connected to the upper core layer and a gap layer is located between the lower magnetic pole layer and the upper magnetic pole layer, or the magnetic pole layer formed of an upper magnetic pole layer connected to the upper core layer. A gap layer is located between the upper magnetic pole layer and the lower core layer. The upper magnetic pole layer, the lower magnetic pole layer, or the upper magnetic pole layer and the lower magnetic pole layer are plated with the soft magnetic film.
In plating the magnetic pole portion, a frame having a narrow space for plating the magnetic pole portion may be formed on the facing surface and in the narrow space, the track width Tw may be restricted to the range of about 0.05 to 0.5 μm, the thickness of the upper magnetic pole layer may be restricted to the range of about 0.1 to 5.0 μm, and the thickness of the lower magnetic pole layer may be restricted to the range of about 0.1 to 5.0 μm. The upper magnetic pole layer, the lower magnetic pole layer, or the upper magnetic pole layer and the lower magnetic pole layer may be plated in the narrow space using the plating bath, in which a plurality of crystals having a fine crystal structure with an average crystal grain diameter of about 1 μm or less exist in any portion of the track width Tw as viewed in the width direction.
According to another embodiment, there is provided a method of manufacturing a recording head of a perpendicular magnetic recording type, the recording head includes a main magnetic pole layer restricting a track width Tw to a surface facing a recording medium, wherein the main magnetic pole layer is plated with a soft magnetic film by using the above-mentioned method. When plating the main magnetic pole layer, a frame having a narrow space for plating the main magnetic pole layer may be formed on the facing surface and in the narrow space, the track width Tw may be restricted to the range of about 0.1 to 1.0 μm, and the thickness of the main magnetic pole layer may be restricted to the range of about 0.1 to 2.0 μm. The main magnetic pole layer may be plated in the narrow space using the plating bath, in which a plurality of crystals having a fine crystal structure with an average crystal grain diameter of about 1 μm or less exist in any portion of the track width Tw as viewed in the width direction.
The lower magnetic pole layer, the upper magnetic pole layer, or the main magnetic pole layer, which is plated with the soft magnetic film, may have a plurality of crystals in any portion in the thickness direction as viewed in the track width Tw direction.
The plating bath composition can be used to minutely form a soft magnetic film with a saturated magnetic flux density Bs of 2.39 T or more, in which only N and O are added as impurity elements to a CoFe plating film, even in the narrow space using fine crystals.
In the soft magnetic film according to the present embodiments, since impurities such as C, S, Cl, and B are not contained in the film, the saturated magnetic flux density Bs can be increased, and specifically it is possible to make the saturated magnetic flux density Bs of 2.39 or more. It can be formed as a fine crystal structure with an average crystal grain diameter of about 0.1 μm or less.
In the manufacturing method of a soft magnetic film according to the present embodiments, it is easy to uniformalize a crystallinity of a plated film, since a temporal change can be reduced compared to an known plating bath to which the acetic acid and the boric acid added, and it is possible to improve a stability of a pH of a plating bath compared to the known plating bath from also having a value of pKa that the known plating bath did not have.
It is possible to increase a plating formation rate since an acetic acid that easily forms Co or Fe and a complex in the plating bath is not added. Since it is possible to increase a plating formation rate, it is not necessary to make densities of Co and Fe in the plating bath higher. Consequently, since it is possible to suppress a degradation of the plating facility. Therefore, as a maintenance frequency can be greatly reduced, it is possible to effectively suppress a degradation of the plating bath generated by frequent overlapping of facility along with devising an improvement of manufacturing efficiency.
Since an acetic acid which has volatility and peculiar irritating odor it not added to a plating bath, a working environment can be improved.
Since boric acid is not added to the plating bath, B is not contained in a plated soft magnetic film. In the thin film magnetic head and the method of manufacturing the same, a thin film magnetic head with a high recording characteristic and an excellent stability can be realized since only N and O are added as impurity elements to a CoFe plating film in a narrow space which is an area of forming an upper magnetic layer or a main magnetic layer, and a soft magnetic film with a saturated magnetic flux density Bs of 2.39 T or more can be minutely formed in a fine crystal.
The thin film magnetic heads of
MR head hi reads a recorded signal by detecting a leaking magnetic field from a recording medium such as a hard disk, using a magnetic resistance effect.
As shown is
Magnetoresistance effect element 10 for example, an aeolotropic magnetoresistance effect (AMR) element, a gigantic magnetoresistance effect (GMR) element and a tunnel type magnetoresistance effect (TMR) element are formed on the lower gap layer 14 in a height direction (Y direction shown in figure) from a surface facing the recording medium, and an upper gap layer 15 of the insulating material is formed on the magnetoresistance effect element 10 and the lower gap layer 14. Moreover on the upper gap layer 15, an upper shield layer 16 formed of a magnetic material such as NiFe is formed. MR head h is constituted by a film stack of from the lower shield layer 13 to the upper shield layer 16.
The upper shield layer 16 also serves as a lower core layer of the recording head h2, a Gd deciding layer 17 is formed on the lower core layer 16. A gap depth (Gd) is restricted by a length size of the surface that faces the recording medium to a front end portion of the Gd deciding layer 17. The Gd deciding layer 17 is formed of, for example, an organic insulating material.
As shown in
As shown in
In the magnetic pole portion 18, a lower magnetic pole layer 19, a nonmagnetic gap layer 20 and an upper magnetic layer 21 are laminated from a bottom.
The lower magnetic layer 19 is directly plated on the lower core layer 16. It is preferable to form a gap layer 20 formed on the lower magnetic layer with nonmagnetic metallic materials that can be plated. Specifically, it is preferable to select at least one of NiP, NiPd, NiW, NiMo, Au, Pt, Rh, Pd, Ru and Cr.
The NiP is preferably used on the gap layer 20. Because the gap layer 20 can adequately become a nonmagnetic condition by forming the gap layer 20 with NiP.
An upper magnetic pole layer 21 formed on the gap layer 20 is magnetically connected with an upper core layer 22 formed thereon.
As described above, when the gap layer 20 is formed of a nonmagnetic metallic material which can be plated as above, it is possible to plate the lower magnetic pole layer 19, the gap layer 20 and the upper magnetic pole layer 21 in a row.
The magnetic pole portion 18 may be formed of two layers of the gap layer 20 and the upper magnetic pole layer 21.
As shown in
As shown in
As shown in
As shown in
In the thin film magnetic head HA shown in
Although a pure CoFe plating film made of only Co and Fe is formed, impurities are infused though it is a small quantity. A magnetic characteristic represented by a saturated magnetic flux density Bs is affected by a type of impurity elements as well as an additional amount of impurity elements.
In this exemplary embodiment, only elements of N and O are added as impurity elements in CoFe plating film as described above.
The magnetic pole layers 19 and 21 are plated by using a plating bath formed of an aqueous solution of Co salts, an aqueous solution of Fe salts, sodium benzene-sulfonic acid and L-glutamic acid, and can increase a saturated magnetic flux density Bs by 2.39 or more since the magnetic pole layer 19 and 21 can plate a CoFe plating bath to which only the elements of N and O are added as impurity elements.
Since a saturated magnetic flux density Bs of a bulk material formed of CoFe alloy is approximately 2.4 T, it has been realized that the saturated magnetic flux densities Bs of the magnetic pole layers 19 and 21 can be the saturated magnetic flux density Bs which are quite close to the bulk material.
The saturated magnetic flux densities Bs of the magnetic pole layers 19 and 20 can be composed higher than 2.39 since impurities such as C, S, Cl, and B are not added to the film of the soft magnetic film formed of the plating bath. If each of the above elements is added to the soft magnetic film, the saturated magnetic flux density Bs are reduced. However, as the magnetic pole layers 19 and 21 are formed on a soft magnetic film which does not contain each of the above elements, a reduction of the saturated magnetic flux density Bs is suppressed to increase the saturated magnetic flux density Bs.
In the magnetic pole layers 19 and 21, the composition ratio of N is in the range of 0 at % to 4.2 at % when a summation of the composition ratios of Co, Fe, N, and O is 100 at %. At the magnetic pole layers 19 and 21, the composition ratio of O is in the range of 0 at % to 10.8 at % when a summation of the composition ratios of Co, Fe, N, and O is 100 at %. If the composition ratios of the N and O as the impurity elements are within the range, as described below, it has been realized that the saturated magnetic flux density Bs can be greatly increased up to 2.45 T to the maximum.
In the magnetic pole layers 19 and 21, the composition ratio of Fe is in the range of about 65.5 wt % to 74 wt % when a summation of the composition ratios of Co and Fe is 100 at %. If the composition ratio of Fe is in the range, as described below, it has been realized that the saturated magnetic flux density Bs of the magnetic pole layers 19 and 21 can be increased up to 2.40 T or more.
At the magnetic pole layers 19 and 21, it is more preferable that the composition ratio of Fe is from about 66 wt % to 73 wt %. If the composition ratio of Fe is in the range, it has been realized that the saturated magnetic flux densities Bs of the magnetic pole layers 19 and 21 can be increased up to 2.42 T or more. In the thin film magnetic head HA, it is possible to improve the recording since it is possible to increase the saturated magnetic flux densities Bs of the magnetic pole layers 19 and 21.
A soft magnetic film to which only N and O are added as impurity elements to a CoFe plating film has a film structure suitable for a soft magnetic film plated in a very narrow space, for example, as an upper magnetic pole layer 21 or a lower magnetic pole layer 19.
A track width Tw shown in
A soft magnetic film to which only N and O are added as impurity elements to a CoFe plating film of the embodiment is formed by a micro crystal structure with an average crystal grain diameter of about 0.1 μm or less. The lowest limit of the average crystal grain diameter is about 0.01 μm.
Since the whole area of the magnetic pole layer 19 and 21 can be formed of a fine crystal structure, by the soft magnetic film being plated as an upper magnetic pole layer 21 or a lower magnetic pole layer 19, it becomes a film structure with a plurality of crystal as viewed in the thickness direction (Z direction shown) whichever part it is on at least a track width Tw. It is more preferable to be a film structure with a plurality of crystal as viewed in the track width direction Tw whichever part it is on a thickness direction.
Accordingly, the magnetic pole layers 19 and 21 can become a minute film formed of a great number of fine crystals to display a stable magnetic characteristic. A stabilization of a recording characteristic can be devised since the surfaces of the lower magnetic pole layer 19 and the upper magnetic pole layer 21 can all approach to a flattening surface and, for example, the gap layer 20 can be plated on the lower magnetic pole layer 19 that is close to a flattening surface.
The magnetic pole layers 19 and 21 can be formed as a soft magnetic film of a fine crystal structure capable of displaying a stable magnetic characteristic with a high saturated magnetic flux density Bs. Thus a recording head with an excellent recording characteristic is capable of adequately dealing with a high recording densification.
The coil layer 44 is surrounded by an insulating layer 45 formed of the polyimide or the resist material to form an upper core layer 46 of a soft magnetic material on the insulating layer 45.
As shown in
In the form shown in
The lower core layer 16 shown in
Although a recording head h2 in a thin film magnetic head HA and HB shown in FIGS. 1 to 3 are all of ‘longitudinal magnetic recording method’ for recording in a horizontal direction with regard to a recording medium surface, the soft magnetic film to which only N and O are added as impurity elements to a CoFe plating film can also be applied to a main magnetic pole layer of a thin film magnetic head of a perpendicular magnetic recording type shown below.
A magnetic head h3 constituting a thin film magnetic head HC shown in
The recording medium M has, for example, a disk shape, and a hard film Ma with a high residual magnetization on its surface and has a soft film Mb with a high magnetic transmittance therein. The recording medium M rotates with a disk center as a pivot center.
A slider 101 is formed of nonmagnetic materials such as Al2O3.TiC, 101a, a facing surface of 101, faces a recording medium M, and when the recording medium M rotates, the slider 101 floats from the surface of the recording medium M by the aerial flow of the surface, or the slider 101 slides on the recording medium M.
On a trailing side edge 101b of the slider 101, a nonmagnetic insulating layer 102 by bioinorganic materials such as Al2O3 or SiO2 are formed. A MR head h4 is formed on this nonmagnetic insulating layer 102.
The MR head h4 has a regeneration element 104 located at a lower shield layer 103 and an upper shield layer 106, and within a bioinorganic insulating layer between the lower shield layer 103 and the upper shield layer 106 (gap insulating layer). The regeneration element 104 is a magnetoresistance effect element, for example, AMR, GMR, or TMR.
On the upper shield layer 16, a plurality of the first coil layer 103 is formed of a conductive material and is formed through a coil insulating foundation layer 107. The first coil layer 108 is made of at least one nonmagnetic material selected from, for example, Au, Ag, Pt, Cu, Cr, Al, Ti, NiP, Mo, Pd, and Rh. Alternatively, a laminated structure of which these nonmagnetic materials laminated is also permissible.
In the periphery of the first coil layer 108, a coil insulating layer 109 formed of a bioinorganic insulating material such as Al2O3 is formed.
An upper surface 109a of the coil insulating layer 109 is formed of a flattening surface, and on this upper surface 101a is formed a main magnetic pole layer 110, which is formed of a predefined length in a height direction from a facing surface h3a, of which a width size to a track width direction (X direction shown) is formed as track width Tw, and extended to a predefined length size L2. The main magnetic layer 110 is plated by a ferromagnetic material, and formed of a soft magnetic film with a saturated magnetic flux density Bs of 2.39 T or more since only N and O are added as impurity elements to a CoFe plating film.
A yoke part 121, which is extended since a width size T2 in a track width direction in a height direction (Y direction shown) becomes wider than the track width Tw, as it is a single body with the main magnetic pole layer 110 from a rear anchor portion 110b of the magnetic pole layer 110. The first magnetic portion 160 is made of this main magnetic pole layer 110 and the yoke portion 121 (refer to
Specifically, the track width Tw is formed in the range of about 0.1 μm to 1.0 μm, and the length size L2 in the range of about 0.1 μm to 1.0 μm.
The yoke portion 121 is approximately 1 μm to 100 μm at a part where a width size of a track width direction (X direction shown) is the largest, and length size L3 in a height direction of the yoke portion 121 is approximately 1 μm to 100 μm.
As shown in
On the main magnetic pole layer 110 and the yoke portion 121 and on the insulating material layer 111, a gap layer 112 is arranged by bioinorganic material such as alumina or SiO2.
As shown in
As shown in
In the periphery of the second coil layer 114, a coil insulating layer 115 formed of a bioinorganic insulating material such as Al2O3 are formed, and a return pass layer 116 which is the second magnetic portion 161, is formed from the top of this coil insulating layer 115 through the gap layer 112 by a ferromagnetic material such as Permalloy.
As shown in
The anterior end 116 of the return pass layer 116 is exposed on a surface facing a recording medium h3a. At a side farther from the recording medium M than the facing surface h3a, a connection portion 116b of the return pass layer and the main magnetic pole layer 110 is connected. Herewith, a magnetic path passing through the return pass layer 116 from the main magnetic pole layer 110 is formed.
On the gap layer 112 and at a location distant from a facing surface to a recording medium h3a as much as a predefined distance, a Gd deciding layer 117 is formed of a bioinorganic or an organic material. A gap depth length of the recording head h3 is defined by a distance from the surface facing a recording medium h3a to an edge of an anterior end of Gd deciding layer 117.
At a side of a height direction of the connection portion 116b of the return pass layer 116 (Y direction shown), a lead layer 118 extended from the second coil layer 114 is formed through a coil insulating foundation layer 113.
At the recording head h3, when a recording current is granted to the first coil layer 108 and the second coil layer 114 through the lead layer 118, a recording magnetic field is inducted to the main magnetic layer 110 and the return pass layer 116 by a current magnetic field that flows at the first coil layer 108 and the second coil layer 1145, and for the facing surface h3a, a magnetic flux φ1 of a recording magnetic field springs out from an anterior end 110a of the main magnetic layer 110 and the magnetic flux φ1 of the recording magnetic field transits a soft film Mb by penetrating a hard film Ma of the recording medium N, and herewith, the magnetic flux φ1 returns to the anterior end 116a of the return pass layer 116 after a recording signal is recorded on the recording medium M.
The main magnetic pole layer 110 shown in
A soft magnetic film to which only N and O are added as impurity elements to a CoFe plating film of the embodiment is formed of a micro crystal structure with an average crystal grain diameter of about 0.1 μm or less.
The main magnetic pole layer 110 is a narrow structure formed of a track width Tw of about 0.1 to 1.0 μm, thickness size Ht of about 0.1 to 2.0 μm, length size of depth L2 of about 0.1 μm to 1.0 μm, and the soft magnetic film is plated as the narrow-structured main magnetic pole layer 110, and the whole area of the main magnetic pole layer 110 is formed of a fine crystal structure. Thus a plurality of crystals exist as viewed in the thickness direction (Z direction shown) whichever part it is in a track width Tw, and preferably becomes a film structure in which a plurality of crystals exist as viewed in a track width direction Tw whichever part it is in a thickness direction.
Accordingly, the main magnetic pole layer 110 can display a stable magnetic characteristic since it becomes a minute film formed of a large number of fine crystals. A stabilization of a recording characteristic can be devised since a surface of the main magnetic pole layer 110 can approach a flattening surface to plate the gap layer 112 on the flattened main magnetic pole layer 110.
Since the main magnetic pole layer 110 can be formed as a soft magnetic film capable of displaying a stable magnetic characteristic by a high saturated magnetic flux density Bs, a perpendicular magnetic recording head with an excellent recording characteristic is capable of appropriately coping with a high recording densification.
With regard to a recording head h3 shown in
A soft magnetic film according to the embodiment with a saturated magnetic flux density of 2.39 T or more to which only N and O are added as impurity elements to a CoFe plating film, can also be used for a flat magnetic element such as an inductor.
A plating method of the magnetic pole layers 19 and 21 shown in
For example, CoS04.7H2O is used for a water solution of the aqueous solution of Co salts. FeSO4.7H2O is used for a water solution of the aqueous solution of Fe salts. As sodium benzene-sulfonic acid has a function of bringing in the oxygen of the plating bath by combining with the O element in the plating bath and turning into a benzene-sulfonic acid, it can adequately suppress a content of O element of a plated soft magnetic film. As shown in
Generally, when a pKa of a certain solution is a value of A a great quantity of acid or alkali is necessary to change the pH value of A of the solution, when the pH of the solution is A, the same value as the pKa. For example, it is known that a buffering capacity is brought out at the pH same as the value A of pKa. It is preferable that the plating bath brings out a buffering capacity thereof since it is easier to maintain the plating bath in a stable condition.
In the manufacturing method of the existing soft magnetic film described in Patent Document 1, an acetic acid and a boric acid were added to a plating bath used for this method (hereinafter referred to as ‘known plating bath’). As shown in
Correspondingly, the plating bath used for the manufacturing method of the magnetic pole layers 19 and 21 (soft magnetic film) of the present embodiment (hereinafter referred to as “the plating bath according to the present embodiment”) has three pKas of about 2.19, 4.25 and 9.67 as shown in
The two pKas of about 4.25 and 9.67 of the plating bath according to the present embodiment contribute to an improvement of a plating efficiency by mainly contributing to a stability of pH value in the vicinity of a surface pole of a plated object.
As described below, if pHs of the entire plating bath are adjusted to a value of 2.19, it is predicted that pH of a plating bath in the vicinity of a surface pole of a plated object in a plating bath will rise up to about 4.25 or close to 9.67. Therefore, a soft magnetic film with a good crystallinity can be formed since only N and o are added as impurity elements to a plating film to have a saturated magnetic flux density of 2.39 T or more by the plating bath according to the present embodiment to which L-glutamic acid is added.
The plating bath according to the present embodiment also has a pKa of about 2.19 which does not exist in the known plating bath. This pKa contributes to the stability of the pH value of the whole plating bath. Therefore, in the plating bath according to the present embodiment, in addition to guaranteeing a stability of a plating bath likewise the known plating bath to which the acetic acid and the boric acid is added, in the plating bath according to the present embodiment, it is easy to uniformalize a crystallinity of a plated film since a stability of a plating bath can be improved compared to the known plating bath to enable a suppression of a notable pH change since it has a value of about 2.19 of pKa that the known plating bath did not have.
Unlike the plating film of the prior art, an acetic acid is not added to the plating bath according to the present embodiment. Since an acetic acid is apt to form a complex with Co or Fe, a plating formation rate of a soft magnetic film formed in a plating bath including an acetic acid gets notably lower. However, a plating formation rate can be increased since an acetic acid apt to form a complex with Co or Fe is not added to the plating bath according to the present embodiment.
Since the composition ratio of Co or Fe in a soft magnetic film can be raised in the plating bath of the present embodiment as described above, it is not necessary to raise the densities of Co or Fe in the plating bath. Accordingly, for example, a degradation of plating facilities such as a filter or a plating tank used for circulating a plating bath can be suppressed. Accordingly, the maintenance, for example, a substitution of plating facilities can be greatly reduced. It is possible to effectively suppress a degradation of a plating bath due to a stoppage of a plating bath's circulation due to a frequent overlap of facility substitution, or an interfusion of wastes during facility substitution, along with devising an improvement of a manufacturing efficiency.
Due to a very high volatility of an acetic acid, a density of an acetic acid in the plating bath gets rapidly lower by a volatility of an acetic acid, therefore, a temporal change of a bath composition in the known plating bath to which the acetic acid is added is very large which results to a poor stability of the plating bath. It is not preferable for a working environment since the acetic acid, which has an irritating odor of its own, volatiles from a plating bath and makes the surrounding environment worse.
Correspondingly, an acetic acid is not added to the plating bath. Therefore, a stability of a plating bath becomes excellent, and the working environment can be adequately suppressed from getting worse at the same time since a temporal change of the bath composition of the plating bath can be reduced.
In the plating bath according to the present embodiment, it has been realized that a saturated magnetic flux density Bs of a plated soft magnetic film does not decrease even though a boric acid is not added to the plating bath.
In the plating bath according to the present embodiment, it is preferable to add the sodium benzene-sulfonic acid within the range from about 0.01 g/l to 0.05 g/l. It has been realized that if the sodium benzene-sulfonic acid is added within the range, a saturated magnetic flux density Bs can be certainly increase to 2.42 T or more as described below.
It is preferable to add the L-glutamic acid within the range from about 0.1 g/l to 0.5 g/l. It has been realized that if the L-glutamic acid is added within the range, a saturated magnetic flux density Bs can be certainly increased to 2.42 T or more as described below.
In the plating bath according to the present embodiment, it is preferable to use L-glutamic acid, since a solubility of a plating bath is very low if a D-glutamic acid which is an isomeric form or its sodium chloride is used instead of the L-glutamic acid.
For example, C6H4CONNaSO2 contains impurities such as S (sulfur) which causes erosion not included in the plating bath according to the present embodiment. A compound that includes a precious metal such as Rh added to improve a corrosion resistance in the past is not added.
The magnetic pole layers 19 and 21 are plated by an electric plating method using the plating bath. Optimally, the electric plating method is that of using a pulse current.
In the electric plating method using a pulse current, a time flowing a current and a vacant time not flowing a current is arranged when plating by, for example, repeating ON/OFF of a current control element. By arranging a time of which a current is not flowing as above, it is possible to mitigate a deflection of the current density distribution when plating, compared to using a direct current as in the past, even if the magnetic layers 19 and 21 are plated by degrees and a density of Fe ion occupying the plating bath is increased.
It is preferable to make a duty ratio of the pulse current approximately 0.1 to 0.5 by, for example, repeating ON/OFF by a cycle of several seconds.
Since it is possible to mitigate a deflection of the current density distribution when plating in the electric plating method by a pulse current as above, it is possible to miniaturize the crystal of the magnetic pole layer more compared to an electric plating method by a direct current. The Fe content added to the magnetic layers 19 and 21 can be increased more than before.
In case of using the electric plating method by a pulse current, the Fe amount included in the magnetic layers 19 and 21 can be easily regulated to be suitable in the range of about 65.5 wt % to 74 wt %, preferably within 66 wt % to 73 wt %.
In order to plate a magnetic pole portion 18 shown in
In one exemplary embodiment, it has a saturated magnetic flux density of 2.39 T or more, in which only N and O are added as impurity elements to a CoFe plating film in the narrow space by using a plating bath formed by adding the an aqueous solution of Fe salts, an aqueous solution of Co salts, sodium benzenesulfonate, and L-glumatic acid, and plates a lower magnetic pole layer 19 and an upper magnetic pole layer 21 from a soft magnetic film with a good crystallinity.
The soft magnetic film plates and grows in a fine crystal structure with an average crystal grain diameter of about 0.1 μm or less in the narrow space, so that a plurality of crystals exist as viewed in the thickness direction whichever part it is on a track width Tw direction, and preferably, the soft magnetic film plates and grows in a film structure where a plurality of crystals exist as viewed in the track width Tw direction whichever part it is on a film width direction.
Accordingly, the lower magnetic pole layer 19 and the upper magnetic pole layer 21 are plated minutely as a fine crystal structure in a narrow space, so that a stable magnetic characteristic can be displayed and the surfaces of the lower magnetic pole layer 19 and the upper magnetic pole layer 21 can be effectively close to a flattening surface. Therefore, a recording head h2 with a stable characteristic can be suitably and easily manufactured since a gap layer 20 plated on the lower magnetic pole layer 19 can be plated on a shape with as little irregularity as possible.
A main magnetic pole layer 110 of a recording head h3 of a recording head of a perpendicular magnetic recording type can be formed by a same method as the magnetic pole layer 19 and 21.
For example, in order to plate the main magnetic pole layer 100, a register layer (not shown in a figure) which becomes a frame for forming the main magnetic pole layer 110 on the coil insulating layer 109 is coated, and a narrow space (removing pattern) in an area where the main magnetic pole layer 110 is formed by an exposure development of the register layer. This narrow space has a track width Tw shown in
In this exemplary embodiment, it has a saturated magnetic flux density of 2.39 T or more, in which only N and O are added as impurity elements to a CoFe plating film in the narrow space by using a plating bath formed by adding the an aqueous solution of Fe salts, an aqueous solution of Co salts, sodium benzenesulfonate, and L-glutamic acid, and plates a main magnetic pole layer 110 from a soft magnetic film with a good crystallinity.
The soft magnetic film plates and grows in a fine crystal structure with an average crystal grain diameter of 0.1 μm or less in the narrow space, so that 2 or more crystals exist as viewed in the thickness direction whichever part it is on a track width Tw direction, and preferably, the soft magnetic film plates and grows in a film structure where 2 or more crystals exist as viewed in the track width Tw direction whichever part it is on a film width direction.
Accordingly, the main magnetic pole layer 110 is plated minutely as a fine crystal structure in a narrow space, so that a stable magnetic characteristic can be displayed and the surfaces of the main magnetic pole layer 110 can be effectively close to a flattening surface. Therefore, a recording head h3 with a stable characteristic can be suitably and easily manufactured since a gap layer 110 formed on the main magnetic pole layer 110 can be suitably plated on a shape with as little irregularity as possible.
An upper core layer 46 and a lower core layer 16 shown in
Composition ratios and a current density of a plating bath that formed Example 1 according to the present embodiment are, 12.45 g/l of FeSO4.7 H2O, 1.431 g/l of CoSO4.7 H2O, 0.01 g/l of sodium benzene-sulfonic acid and 0.1 g/l of L-glutamic acid, and the current density is 30 mA/cm2.
A composition and a current density of the known plating bath are as below.
The composition and the current density of the plating bath that formed in Example 1: 122.00 g/l of FeSO4.7 H2O, 53.00 g/l of CoSO4.7 H2O, 12 g/l of acetic acid, 25 g/l of boric acid and 0.50 g/l of sodium chloride, and a current density of 20 mA/cm2.
A composition and a current density of a plating bath that formed Comparative Example 2: 62.95 g/l of FeSO4.7 H2O, 17.54 g/l of CoSO4.7 H2O, 3 g/l of acetic acid, 0 g/l of boric acid, and 0 g/l of sodium chloride, and a current density of 20 mA/cm2.
A composition and a current density of a plating bath that formed Comparative Example 3: 8.73 g/l of FeSO4.7 H2O, 1.4 g/l of CoSO4.7 H2O, 0.01 g/l of sodium benzene-sulfonic acid, 0.1 g/l of L-glutamic acid, 25 g/l of boric acid, and 0 g/l of sodium chloride, and a current density of 30 mA/cm2.
A composition and a current density of a plating bath that formed Comparative Example 4: 8.73 g/l of FeSO4.7 H2O, 1.4 g/l of CoSO4.7 H2O, 0.01 g/l of sodium benzene-sulfonic acid, 0.1 g/l of L-glutamic acid, 0 g/l of boric acid, and 0.5 g/l of sodium chloride, and a current density of 30 mmA/cm2.
For each sample, a temperature of a plating bath is 30° C., a duty ratio of a pulse current is 10%, and a plating time is 30 minutes. These conditions are common to all of the following tests.
A detecting result shown in
As shown in
As shown in
In Comparative Example 1 and Comparative Example 2, it has been realized that a detected quantity of O increased since a boric acid and a sodium chloride is not added.
As shown in
As shown in.
In the Example with respect to the above, as shown in
As shown in
The composition ratio of the plating bath according to the present embodiment is 12.45 g/l of FeSO4.7 H2O, and 1.431 g/l of CoSO47H2O, and the amounts of sodium benzene-sulfonic acid and L-glutamic acid shown in
As shown in
Among the tables shown in
The table shown on the right is an examination on a temporal change of a plating bath from the saturated magnetic flux densities Bs by respectively measuring the saturated magnetic flux densities Bs of, Comparative Examples 5 and 8 plated at a plating bath right after constructing bath, Comparative Examples 6 and 9 plated at a plating bath neglected for 48 hours after constructing bath, and Comparative Examples 7 and 10 formed at a plating bath after forming a soft magnetic film with thickness of 5 μm by a plating bath neglected for 48 hours after constructing bath.
Comparative Examples of 5, 6 and 7 are a soft magnetic film plated at the known plating bath 1, and Comparative Examples of 8, 9 and 10 are soft magnetic films plated at the known plating bath 2.
With regard to the plating bath 1, in case of comparing Comparative Example 5 plated at a plating bath right after constructing bath, to Comparative Example 6 plated at a plating bath neglected for 48 hours after constructing bath, a saturated magnetic flux density Bs of Comparative Example 6 plated at a plating bath neglected for 48 hours after constructing bath is smaller. And in case of comparing Comparative Example 6 plated at a plating bath neglected for 48 hours after constructing bath, to Comparative Example 7 plated at a plating bath after forming a soft magnetic film with thickness of 5 μm by a plating bath neglected for 48 hours, a saturated magnetic flux density Bs of Comparative Example 7 is so low that it can not be measured.
With regard to the plating bath 2, in case of comparing Comparative Example 8 plated at a plating bath right after constructing bath, to Comparative Example 10 plated at a plating bath after forming a soft magnetic film of 5 μm by a plating bath neglected for 48 hours, a saturated magnetic flux density Bs of Comparative Example 10 is smaller.
It has been realized that a saturated magnetic flux density Bs of a soft magnetic film by a temporal change of a plating bath is lowering in the existing bath. It is supposed that this is due to a reduction of a buffering action of a plating bath, as a volatilization of the acetic acid added to the plating bath made progress.
The table shown on the right of
As shown in
As shown in
As shown in
Among the tables in
The table on the right shows a result of measuring a saturated magnetic flux density Bs of Comparative Example 3 formed at the plating bath with boric acid added.
As shown in
As shown in
Accordingly, it has been realized that even though it is a plating bath to which not acetic acid but sodium benzenesulfonate and L-glutamic acid are added, a saturated magnetic flux density Bs decreases if a boric acid is further added. It is supposed that this is because B gets added to a plated soft magnetic film.
Among the tables of
A table on the right shows a result of measuring a saturated magnetic flux density Bs of Comparative Example 4 plated in the plating bath with sodium chloride added.
As shown is
As shown in
Accordingly, it has been realized that even though it is a plating bath to which not acetic acid but sodium benzenesulfonate and L-glutamic acid are added, a saturated magnetic flux density Bs decreases if a sodium chloride is further added. It is supposed that this is because a saturated magnetic flux density Bs gets lower due to a formation of uneven crystal by adding a sodium chloride.
It has been realized that by forming a plating bath including only an aqueous solution of Fe salts, an aqueous solution of Co salts, sodium benzenesulfonate, and L-glutamic acid, a soft magnetic film with a high saturated magnetic flux density of 2.39 T or more, preferably 2.42 T or more can be plated since only N and o are added as impurity elements to a CoFe plating film.
By using a known plating bath 1 and plating bath 2 shown in
The cross-sectional surface's condition from a film width direction of each soft magnetic film were observed by a focused ion beam manufacturing observation device (FIB-SIM (manufactured by SII, type SMI-98009). In a test, an accelerating voltage was 30 kV by using a Ga (gallium) ion beam.
A surface roughness Ra was measured by a contact measuring instrument, and the surface roughness Ra of any of a soft magnetic film plated by a known plating bath 1, a soft magnetic film plated by a known plating bath 2 and a soft magnetic film plated by the embodiment was in the range of 9 to 11A which did not show much change. As described above, it is regarded that there being not much change in the surface roughness Ra of the soft magnetic films plated by the plating bath of the embodiment and also by the known plating bath is due to a measurement of a surface roughness of a soft magnetic film formed over a broad range of a substrate with a diameter of 3 inches and an error of a measurement. However, since a formation area of a recording head plating the soft magnetic film is a very narrow space, a condition of a soft magnetic film plated in such narrow space was measured in the second place.
As shown in
As shown in
The average crystal grain diameter of the soft magnetic films of
When 10 or more crystal grains are not shown on a SIM image surface, an average crystal grain diameter is obtained by conducting the measurement for the entire crystal grains shown on a SIM image surface.
Number | Date | Country | Kind |
---|---|---|---|
2005-268153 | Sep 2005 | JP | national |
2006-219161 | Aug 2006 | JP | national |