Dynamic magnetic information storage or retrieval – Head – Head surface structure
Reexamination Certificate
2000-03-15
2002-06-25
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Head surface structure
C360S235200, C360S235300, C360S236600
Reexamination Certificate
active
06411464
ABSTRACT:
TECHNICAL FIELD
The present invention pertains to magnetic heads that are used as contact-type or floating-type structures with respect to magnetic recording media, such as floppy disks, hard disks, and the like. [The characterizing feature of the present invention is that a surface with fine irregularities, where only the tip of the protrusions at the surface of the bearing surface facing a magnetic recording medium of a sliding member comprising polycrystalline nonmagnetic ceramics is an almost a flat surface, is formed by chemical etching using an etching solution with a needed composition without altering the properties of the smooth surface of the core member that has been finished by polishing. The present invention presents a magnetic head and a production method of good productivity with which improvement of sliding performance with no damage to the magnetic recording medium is expected and the smooth surface of the core member is maintained and there is no deterioration of electromagnetic properties.]
BACKGROUND ART
In addition to floppy disks (FD) of conventional recording capacity, large-capacity, high-density floppy disks are now being used as a result of improved recording media and large-capacity floppy disks exceeding 100 MB are being developed.
The mirror finish of the bearing surface has been very important to electro-magnetic properties of contact-type magnetic heads used in FD drives in the past, but when used, there are problems in that there is an increase in the turning load of the recording medium, an adsorption phenomenon is seen, etc. In order to prevent this adsorption, etc.,(sticking), it is necessary to increase driving torque. However, the above-mentioned problems have become more obvious because low-torque motors are being used today to conserve electricity.
Polycrystalline nonmagnetic ceramics, such as CaO—TiO
2
systems, AlTiC systems, MnO—NiO systems, CaTiO
3
—NiO systems, CaO—MgO—TiO
2
systems, CaO—MgO—TiO
2
—SiO
2
systems, CaO—MgO—TiO
2
—SiO
2
—Al
2
O
3
systems, etc., are being used for the sliding member of magnetic heads today in order to improve electromagnetic properties in response to the increase in density.
Moreover, the bearing surface facing the disk of a floating-type magnetic head, which has a structure whereby the disk floats as it turns at high speed and is used in hard disk drives (HDD), etc., must have a mirror finish to a higher accuracy and its floating performance must be guaranteed. However, an adsorption phenomenon between the disk and the bearing surface of the magnetic head that come into contact when the drive stops, or so-called sliding performance problems, develop when the mirror finish is more perfect and as a result, the CSS properties of the magnetic head are diminished.
In short, if the bearing surface, which is the face of the magnetic head that faces the recording medium, is polished to a mirror finish to the point that the lapping residue layer produced by the previous process is all but completely removed, there will be problems with the above-mentioned adsorption, etc., on contact.
Various structures, such as a structure where a core member is inserted into the sliding member or a structure where the core member is attached to or buried in the sliding member, are used for the magnetic head. All conventional structures use the following 2 methods to prevent the above-mentioned problems with adsorption, etc., for the purpose of realizing both good electrical properties and sliding performance. That is, the method has been used whereby the bearing surface of the sliding member and the core member of a magnetic head that face the magnetic recording medium are simultaneously polished to such an extent that the above-mentioned adsorption does not occur when they are polished to a mirror finish, or only the bearing surface of the sliding member is roughed to a certain extent after the above-mentioned polishing to a mirror finish.
Moreover, Japanese Patent Publication No.04-34203 presents a method whereby once the bearing surface of a sliding member made from Mn—Zn ferrite or Ni—Zn ferrite has been polished to a mirror finish, reactive ion etching is performed to obtain the desired rough surface. Furthermore, Japanese Patent Laid-Open No.02-276074 presents a method whereby after the sliding surface of a sliding member made of Mn—Zn ferrite has been given a mirror finish, reverse sputtering is performed to make pits that are 50 to 100 A deep. However, this means cannot be used on polycrystalline nonmagnetic ceramics materials, and the above-mentioned long procedure time and poor productivity are problems.
Japanese Patent Laid-open No.02-310869 presents a method whereby the bearing surface or a sliding member made from a magnetic ceramics such as Mn—Zn ferrite, Ni—Zn ferrite, etc., is roughed with a hydrochloric acid etching solution. Since both the sliding member and the core member are roughed, there are problems with this method in that a lapping residue layer is made, there are defects and scratches made in the core junction, leading to deterioration of the magnetic properties, and it takes time to align the head at the core junction, resulting is poor productivity.
Furthermore, Japanese Patent Laid-open No.08-36852 presents a method whereby the bearing surface of the sliding member made from a non-magnetic ceramics such as CaTiO
3
or AlTiC, etc., is treated with an aqueous etching solution comprising oxidizing agent and acid or oxidizing agent and alkali so that this bearing surface is roughed without simultaneously eroding the core member with a mirror finish.
A simple device is used and therefore productivity is good with the above-mentioned method of etching with an aqueous solution comprising an oxidizing agent and acid or oxidizing agent and alkali. However, since the bearing surface that faces the magnetic recording medium that is obtained has a rough surface with irregularities that have sharp peaks and deep crevices, the tip of these protrusions being the sharp peaks, there are problems in that the magnetic recording medium is easily damaged and improvement of good sliding properties without obtaining sufficient air flow is undesirable. In particular, there is a problem in that the etching solution, which consists of an aqueous solution comprising oxidizing agent and alkali, dissolves the nonmagnetic ceramics component, and etching performance therefore is easily saturated.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide a magnetic head with both good electro-magnetic properties and sliding performance. Moreover, another purpose of the present invention is to give the bearing surface facing the magnetic recording material a mirror finish until the lapping residue layer made by the previous processes can be all but completely removed and then to form a surface with fine irregularities at only the bearing surface facing the magnetic recording medium of the sliding member in order to make a fine air flow path altering the properties of the smooth surface of the above-mentioned core member that has been finished by polishing. Another purpose of the present invention is to present a magnetic head and a production method of excellent productivity with which improvement of sliding performance and improvement of magnetic properties can be realized because the surface with fine irregularities that has been formed will not damage the magnetic recording medium.
The inventors felt that it was necessary to have good air flow between the recording medium and magnetic head during sliding in order to improve sliding performance. They further felt that in order to realize this good air flow, it was necessary to improve the cross section shape in the direction of depth at the bearing surface of the sliding member. Consequently, they felt that although the tips of the protrusions forming the rough surface with irregularities of the sliding member of conventional heads are sharp peaks relative next to deep crevices with respect to the magnetic recording medium, the tips of these pro
Fujii Hiromitsu
Nakamura Katsuhiro
Namekata Takehiko
Yokouchi Shin
Dykema Gossett PLLC
Evans Jefferson
Sumitomo Special Metals Co. Ltd.
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