JP2007223842A - Alumina sintered body and jig for machining and assembling magnetic head using the same - Google Patents

Abstract

When a sintered alumina material containing a conductivity imparting agent is used as a jig for assembling and processing a magnetic head in particular, the volume resistivity can be reduced, but the mechanical strength should be increased. If the external pressure is repeatedly applied to the magnetic head machining assembly jig, it is easily damaged.
The alumina-based sintered body of the present invention has magnetic phase titanium oxide in the grain boundary phase, and the magnetic phase titanium oxide has higher conductivity than the specific ratio titanium oxide (TiO ₂ ). It also has the characteristics of chemical stability, especially high corrosion resistance in a corrosive atmosphere, so the grain boundary phase is hard to be corroded, so it has high strength while maintaining conductivity, especially magnetic head processing When used as an assembly jig, the electric charge charged to the magnetic head can be quickly released, and the magnetic head machining assembly jig can be damaged even if external pressure is repeatedly applied to the magnetic head machining assembly jig. And can be highly reliable for a long period of time.
[Selection] Figure 4

Description

  The present invention relates to an alumina-based sintered body having a mechanical property higher than that of a general conductive alumina-based sintered body and having a static electricity removing action capable of releasing static electricity at an appropriate speed. , Relating to a magnetic head machining assembly jig used in a machining process or an assembly process of a magnetoresistive effect (MR) head or a giant magnetoresistive effect (GMR) head used in a hard disk drive or a tape drive which is a high density recording apparatus It is.

Alumina sintered body generally has a high melting point, high strength, high hardness, electrical insulation, high thermal conductivity,
Since it is chemically stable, it is used in a wide range of applications such as heat-resistant materials, structural materials, grinding / polishing materials, biomaterials, and electrical insulating materials such as IC substrate packages. Such an alumina sintered body usually has an electrical insulating property of about 10 ¹⁴ Ω · cm, but it is conductive for the purpose of developing it in various applications by taking advantage of mechanical and chemical properties. Various attempts have been proposed.

For example, in Patent Document 1, selected from the group consisting of 77 to 96% by volume of alumina particles and titanium carbide, titanium nitride, zirconium carbide, zirconium nitride, hafnium carbide, hafnium nitride, niobium carbide, niobium nitride, tantalum carbide, and tantalum nitride. 1 to 5% by volume of the conductive compound particles, the average particle diameter of the alumina particles and the conductive compound particles is 5 μm or less, and the surface resistivity is 10 ⁶ to 10 ¹⁰ Ω / An alumina sintered body having a cm ² has been proposed.

Also, in Patent Document 2, titanium nitride is contained in an amount of 25 to 10% by mass, titanium nitride ultrafine particles are uniformly dispersed in the crystal grains of alumina, the relative density is 96% or more, and the volume resistivity is 1 × 10 ^{4 to} 5 An alumina sintered body having a size of 10 ⁶ Ω · cm has been proposed.

Patent Document 3 proposes an alumina sintered body containing 0.6 to 3% by mass of titanium oxide and having a surface resistivity of 10 ⁴ to 10 ¹¹ Ω / □.

Patent Document 4 describes that an alumina sintered body having a volume resistivity of 10 ⁶ to 10 ⁹ Ω · cm was used for a magnetic head machining assembly jig.
Japanese Patent No. 3313380 JP-A-8-119722 JP 2004-352572 A Japanese Patent Laid-Open No. 11-25416

  However, although the alumina-based sintered body of Patent Document 1 is effective for removing electrification of a charged electronic component, since the density and strength are low, the above-described process or assembly process for producing a magnetic head is performed. When used as a magnetic head machining assembly jig for holding a magnetic head substrate, it is easy to shed grains, and when an external pressure is repeatedly applied to the magnetic head machining assembly jig, the magnetic head machining assembly jig is likely to be damaged. Had a problem.

The alumina sintered body of Patent Document 2 has a volume resistivity of 1 × 10 ^{4 to} 5 × 10 ⁶ Ω · cm, but has a mechanical strength of about 400 MPa, and is used as a magnetic head machining assembly jig. When used, it had the same problem as the alumina sintered body of Patent Document 1.

In addition, the alumina sintered body of Patent Document 3 contains titanium oxide, has a surface resistance of 10 ⁴ to 10 ¹¹ Ω / □, and improved thermal shock resistance, but has a mechanical strength of 300 to 500 MPa. It has a problem of low and wear resistance.

  Furthermore, since the magnetic head machining assembly jig of Patent Document 4 contains titanium carbide and has a black color, a magnetic head substrate made of an alumina-titanium carbide composite sintered body is used as a jig. When pasting and polishing, the alumina-titanium carbide composite sintered body exhibits the same black color as the jig, so the automatic visual inspection machine may mistakenly identify the jig and the magnetic head substrate in the inspection process. In many cases, the work efficiency was reduced.

  The alumina sintered body of the present invention is characterized by having alumina as a main crystal phase and having a magnetic phase titanium oxide in the grain boundary phase.

  Moreover, 5-10 mass% of the said magnesium phase titanium oxide is included, It is characterized by the above-mentioned.

Furthermore, a magnetic head machining assembly jig comprising the alumina sintered body and holding the magnetic head substrate in a machining process or assembling process for producing a magnetic head from the magnetic head substrate, the volume specific The resistance is 10 ⁶ to 10 ⁹ Ω · cm.

  Furthermore, the chromaticness index b * in the CIE 1976 L * a * b * color space on the surface is -10 or less.

  The present invention has been made in order to solve the above-described problems. An alumina sintered body having improved mechanical characteristics while maintaining electrical conductivity, and a magnetic head machining assembly jig using the same In addition, when used in the magnetic head processing and assembly jig of the present invention, the automatic visual inspection machine prevents erroneous recognition of the magnetic head processing and assembly jig and the magnetic head substrate. It is also intended to suppress a decrease in efficiency.

The alumina-based sintered body of the present invention contains magnetic phase titanium oxide in the grain boundary phase, and this magnetic phase titanium oxide has higher conductivity than titanium oxide (TiO ₂ ) with a specific ratio and is chemically stable. In particular, the grain boundary phase is not easily corroded because it has a feature of high corrosion resistance, particularly in a corrosive atmosphere. Therefore, an alumina sintered body having high strength can be obtained while maintaining conductivity.

  Moreover, by containing 5-10 mass% of magnesium phase titanium oxide, in addition to the above-mentioned effect, it can be set as the alumina sintered compact with the stable volume specific resistance value.

The magnetic head machining assembly jig of the present invention is made of the alumina sintered body and has a volume resistivity of 10 ⁶ to 10 ⁹ Ω · cm, and thus has high strength while maintaining conductivity. Therefore, the electric charge charged to the magnetic head can be quickly released, and the magnetic head machining assembly jig will not be damaged even if an external pressure is repeatedly applied to the magnetic head machining assembly jig.

  In addition, the jig for assembling and processing the magnetic head has an alumina-carbonized carbon with a strong blue tone and a black color by setting the chromaticness index b * in the CIE 1976 L * a * b * color space of the surface to -10 or less. The magnetic head substrate made of a titanium-based sintered body can be easily identified, and a reduction in work efficiency can be suppressed.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing the crystal structure of the alumina sintered body of the present invention.

  The alumina sintered body 1 of the present invention is composed of alumina particles 2 as a crystal phase, and has a magnesium phase titanium oxide 3 in its grain boundary phase.

  The grain boundary phase has magnetic phase titanium oxide, and quickly maintains the sintered body with the magnetic phase titanium oxide, which is a conductive compound, while maintaining the mechanical strength, wear resistance, and heat resistance of alumina. Since it has high strength, especially when used as a magnetic head machining jig, it can quickly release the electric charge charged on the magnetic head, and the magnetic head machining assembly jig Even if external pressure is repeatedly applied to the magnetic head, the magnetic head machining assembly jig will not be damaged.

Here, the magnetic phase titanium oxide is represented by the molecular formula Ti _n O _2n-1 (n = 3 to 10), and has high durability in an oxidizing corrosion atmosphere, and a specific ratio of titanium oxide (TiO ₂ ). It is characterized by higher conductivity. The magnetic phase titanium oxide contained in the grain boundary phase is an energy dispersive X-ray spectroscopic analysis (EDS) by observing the grain boundary phase of an alumina sintered body into a flake shape by an ion milling device with a transmission electron microscope. Thus, Ti and O can be easily identified by calculating the ratio of the elements Ti and O constituting the magnetic phase titanium oxide.

  More specifically, when observing the grain boundary phase of a sample with a transmission electron microscope, the acceleration voltage applied to the sample is 200 kV, and the ratio of elements Ti and O is calculated by energy dispersive X-ray spectroscopy (EDS). In this case, the spot diameter is 1 nm, the measurement time is 50 seconds, the measurement energy width is 0.12 to 20.48 keV, the ratio of the elements Ti and O is semi-quantitatively calculated by a thin film approximation method, and the number of atoms constituting the magnetic phase titanium oxide You can ask for.

Such a ratio of the magnesium phase titanium oxide in the alumina sintered body affects the mechanical strength, wear resistance and electrical conductivity. The magnetic phase titanium oxide has electrical conductivity, but has lower strength and hardness than alumina. Therefore, when the ratio of the magnetic phase titanium oxide is high, the mechanical strength and wear resistance are low, and when the ratio is low, the conductivity is low. In order to obtain an alumina sintered body having both mechanical strength, wear resistance and conductivity, it is preferable that the ratio of the magnesium phase titanium oxide in the alumina sintered body is 5 to 10% by mass. By setting it within this range, the three-point bending strength can be 500 MPa or more, the volume resistivity can be 10 ⁶ to 10 ⁹ Ω · cm, and the polishing amount per unit time when polished under the following conditions is 6 μm / A sintered body having high wear resistance and less than time can be obtained.

On the other hand, if the ratio of the magnesium phase titanium oxide in the alumina sintered body is less than 5% by mass, the volume resistivity may exceed 10 ⁹ Ω · cm, and if it exceeds 10% by mass, the three-point bending strength will be less than 500 MPa. Or the polishing amount per unit time may exceed 6 μm / hour. Furthermore, it is more preferable that the content of the magnesium phase titanium oxide is 7 to 10% by mass.

  The three-point bending strength and volume resistivity can be determined in accordance with JIS R 1601-1995 and JIS C 2141-1992, respectively.

Further, the polishing amount per unit time can be measured using the polishing apparatus shown in FIG. 2, and FIG. 2 shows a schematic configuration diagram of the polishing apparatus. The polishing disk 5 is rotated by a driving unit (not shown) in a state where the slurry-like polishing liquid 6 is supplied from the container 7, and the alumina sintered body 1 disposed in the circular polishing jig 8 is the polishing disk. 5 is configured to be rotated and polished while receiving a predetermined pressure. The polishing conditions were as follows: a slurry of polishing slurry 6 having a pH of 8.1 in which diamond abrasive grains having an average particle diameter of 0.1 μm were dispersed at a concentration of 0.5 g / l, flatness of 10 μm or less, and Vickers hardness (H _v ). An alumina sintered body having a surface of 10 mm × 10 mm substrate using a 78 MPa tin polishing disk 5 and a disk-shaped polishing jig 8 is shown in FIG. Are arranged circumferentially at equal intervals, and a pressure of 0.08 MPa and a peripheral speed of 0.5 m / sec are supplied while supplying the polishing liquid 6 to the polishing board 5. Further, the polishing apparatus 4 is a type 9 manufactured by Lapmaster SFT, and the polishing disk is formed by forming a rectangular groove in a spiral shape and setting the interval between adjacent grooves to 0.3 mm.

  Such an alumina sintered body can be suitably used for holding and processing the magnetic head substrate in a processing step for manufacturing the magnetic head from the magnetic head substrate.

  FIG. 4 is a perspective view showing a transfer tool which is an embodiment of the magnetic head working / assembling jig of the present invention, and FIG. 5 is a perspective view showing a use state of the transfer tool.

  This jig is called a transfer tool 9, and is made of a plate-like body having a deformed through hole 10, and polishing a magnetic head substrate (hereinafter simply referred to as a substrate) 11 made of an alumina-titanium carbide composite sintered body. It is used for.

  When the substrate 11 is adhered to the lower surface 12 of the transfer tool 9, the upper surface 13 side is held, and the substrate 11 is elastically pressed by the through hole 10 when pressed against the rotating polishing disk 5 and polished. The thickness of the substrate 11 can be adjusted uniformly. Other than this transfer tool 9, it can also be suitably used as a jig for holding the substrate 11 when processing it by ion milling, or as a jig for holding the manufactured magnetic head when assembling the apparatus. This is because the charge charged on the magnetic head can be quickly released through the magnetic head assembling jig. When the magnetic head machining assembly jig is a transfer tool, external pressure is repeatedly applied to the lower surface 12, but the magnetic head machining assembly jig is not damaged.

  In particular, it is preferable to use the alumina sintered body 1 containing 5 to 10% by mass of magnetic phase titanium oxide as a jig for assembling and machining a magnetic head, and the magnetic head machining and assembly having mechanical strength, wear resistance and conductivity. It is because it can be set as a jig for use.

  By the way, since the magnetic head substrate made of an alumina-titanium carbide composite sintered body and the magnetic head obtained from this magnetic head substrate exhibit a black color, the magnetic head machining assembly jig has a chromatic color other than black. Thus, erroneous recognition by the automatic visual inspection machine does not occur, and a reduction in work efficiency can be suppressed.

  In particular, it is preferable that the chromaticness index b * in the CIE1976L * a * b * color space on the surface of the jig for assembling and processing the magnetic head is −10 or less, and alumina having a strong blue tone and exhibiting black The magnetic head substrate made of a titanium carbide-based composite sintered body can be easily identified, and a reduction in work efficiency can be suppressed.

  In addition, the value of the chromaticness index b * in the CIE 1976 L * a * b * color space on the surface of the magnetic head machining assembly jig is obtained by measuring in accordance with JIS Z 8722-2000. For example, a spectrocolorimeter (Konica Minolta Holdings Co., Ltd. CR-200) can be used, and the light source can be measured by setting the CIE standard light source D65 and the measurement diameter to 8 mm.

  In particular, the brightness index L * in the CIE 1976 L * a * b * color space on the surface of the magnetic head machining assembly jig is 32 to 36, and the chromaticness indices a * and b * are 0.2 to −0.5, respectively. -10 to -12 is preferable from the viewpoint of aesthetics, and both the lightness index L * and the chromaticness index a * can be measured by the same method as described above.

  The magnetic head machining assembly jig of the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. For example, as shown in FIG. It can also be used as tweezers 11 that sandwiches the substrate 9.

  Next, the manufacturing method of the alumina sintered body of this invention is demonstrated.

In order to obtain the alumina sintered body of the present invention, 70 to 90% by mass of alumina powder having an average particle size of 0.3 to 0.7 μm and 10 to 30% by mass of titanium oxide (TiO ₂ ) powder having an average particle size of 10 to 100 nm. Is mixed into a raw material and mixed uniformly with a ball mill, vibration mill, colloid mill, attritor, high-speed mixer or the like. In order to more compact to promote sintering, _Yb 2 _O 3 with respect to formulation _material, Y ₂ O 3, at least one kind of MgO may be added 0.1 to 0.2 wt% .

In addition to the above-described titanium oxide (TiO ₂ ) powder, a magnetic phase titanium oxide powder may be used from the beginning.

  The average particle size of the alumina powder affects the moldability and sinterability. The average particle size of the alumina powder is set to 0.3 to 0.7 μm because the average particle size of alumina is 0.7 μm. If it exceeds, the densification of the sintered body becomes insufficient and the strength is lowered, and if it is less than 0.3 μm, the formability is liable to be lowered, and therefore control in sintering becomes difficult. By setting the average particle size of the alumina powder to 0.3 to 0.7 μm, densification is promoted and mechanical strength can be increased.

Further, titanium oxide (TiO ₂₎ Average particle size of the powder is sintered, electrical conductivity and affect the dispersibility, the average particle size of the titanium oxide (TiO ₂₎ powder was 10~100nm, the average particle size If the thickness is less than 10 nm, the cohesive force of the titanium oxide (TiO ₂ ) powder is too strong, so that aggregates are easily formed. If the thickness exceeds 100 nm, the sinterability at low temperatures tends to deteriorate. is there. By setting the average particle size of the conductive compound powder to 10 to 100 nm, aggregates are not formed, and sinterability at low temperatures can be improved. At the same time, when the average particle diameter of the titanium oxide (TiO ₂ ) powder is 10 to 100 nm, the volume resistivity can be stabilized.

Incidentally, the alumina powder, the average particle size of the titanium oxide (TiO ₂₎ powder can be measured liquid phase precipitation method, the optical dropping method, a laser scattering diffraction method.

  Next, after adding molding aids such as binders and dispersants to the blended raw materials and mixing them uniformly, various granulators such as rolling granulators, spray dryers, compression granulators, extrusion granulators, etc. To granulate.

Thereafter, the obtained granule is molded into a desired shape by a molding means such as dry pressure molding, cold isostatic pressing, etc. to obtain a molded body, and then in a reducing atmosphere with controlled oxygen partial pressure, 1150 The alumina sintered body of the present invention can be obtained by pressure sintering at 1250 ° C. By controlling the oxygen partial pressure, oxygen atoms are desorbed from titanium oxide (TiO ₂ ) at a specific ratio, and magnetic phase titanium oxide (Ti _n O _2n−1 ) (n = 3 to 10) is generated. If the oxygen partial pressure is increased, the value of n is decreased, and if the oxygen partial pressure is decreased, the value of n is increased. To obtain the magnetic phase titanium oxide Ti ₈ O ₁₅ , for example, the oxygen partial pressure is set to 3 × 10 ^{− What} is necessary is just ⁶ Pa.

  Further, since the pressure sintering temperature affects the sinterability of the alumina sintered body and the dispersibility of the magnetic phase titanium oxide, it is important to set the temperature to 1150 to 1250 ° C. If it is less than 1150 ° C., it cannot be sufficiently sintered. If it exceeds 1250 ° C., the magnetic phase titanium oxide tends to aggregate and the functions inherent to the magnetic phase titanium oxide cannot be fully exhibited. It is. This is because, by setting the pressure sintering temperature to 1150 to 1250 ° C., the magnetic phase titanium oxide can be uniformly dispersed and a dense sintered body can be obtained.

  Of the sintering methods, pressure sintering was selected in order to promote densification and obtain the strength required as a jig for assembling and processing a magnetic head, and the pressing force should be 30 MPa or more. Is preferred.

  Examples of the present invention will be described below.

Example 1
First, a preparation raw material composed of an alumina powder and a titanium oxide (TiO ₂ ) powder whose ratios were adjusted, a binder and a dispersant were uniformly mixed to prepare a slurry. This slurry was put into a spray dryer to form granules, and a molded body was obtained by dry pressure molding. Next, this molded body was placed in a predetermined mold and sintered under pressure at an oxygen partial pressure shown in Table 1 in a nitrogen atmosphere. 1-16 were produced.

  Note that the ratio of alumina and titanium oxide in the sample manufactured by the above-described method is as shown in Table 1.

  The volume resistivity and the three-point bending strength of each sample were measured according to JIS C 2141-1992 and JIS R 1601-1995, respectively.

  In addition, the grain boundary phase of the sample processed into a flake shape by an ion milling apparatus is observed with a transmission electron microscope, and the ratio of elements contained in the grain boundary phase is calculated by energy dispersive X-ray spectroscopy (EDS). The element was identified.

  More specifically, in observation with a transmission electron microscope, the acceleration voltage applied to the sample is 200 kV, and in calculation of the elements Ti and O by energy dispersive X-ray spectroscopy (EDS), the spot diameter is 1 nm, the measurement time is 50 seconds, and the measurement is performed. The energy range was set to 0.12 to 20.48 keV, the ratio of each element was semi-quantitatively calculated by thin film approximation, the number of atoms constituting the magnetic phase titanium oxide and titanium nitride was determined, and the molecular formula is shown in Table 1. .

The polishing amount per unit time (hereinafter referred to as lap rate) was measured using the polishing apparatus shown in FIG. Polishing conditions were a slurry-like polishing liquid 6 having a pH of 8.1 in which diamond abrasive grains having an average particle diameter of 0.1 μm were dispersed at a concentration of 0.5 g / l, a flatness of 10 μm or less, and a Vickers hardness (H _v ) of 78 MPa. An alumina sintered body having a substrate size of 10 mm × 10 mm using a tin polishing disk 5 and a disk-shaped polishing jig 8 is provided in a polishing jig 8 as shown in FIG. The plates were arranged circumferentially at equal intervals, and the pressure of 0.08 MPa and the peripheral speed of 0.5 m / second were set while supplying the polishing liquid 6 to the polishing board 5. Further, the polishing apparatus 4 was a 9 "type manufactured by LAPMASTER SFT, and the polishing board was formed with a rectangular groove in a spiral shape, and the interval between adjacent grooves was 0.3 mm.

A low wrap rate means high wear resistance, and a high lap rate means low wear resistance.

Moreover, the value of the brightness index L * and the chromaticness index a *, b * in the CIE 1976 L * a * b * color space of the polished surface was measured according to JIS Z 8722-2000. More specifically, a spectrocolorimeter (Konica Minolta Holdings, Inc. CR-200) was used, and the light source was set to CIE standard light source D65 and the measurement diameter was set to 8 mm.

As shown in Table 1, the sample No. 1 contains titanium oxide (TiO ₂ ) in the grain boundary phase. No. 16 has a high volume resistivity and lap rate of 1 × 10 Ω · cm and 13 μm / hour, respectively, and a three-point bending strength of 410 MPa, which is unsuitable for use in a magnetic head machining assembly jig.

On the other hand, Sample No. which is the alumina sintered body of the present invention. 1 to 15 contain magnetic phase titanium oxide in the grain boundary phase, so that the volume resistivity is 1 × 10 ^{6 to} 5 × 10 ⁹ Ω · cm, the three-point bending strength is as high as 489 Pa or more, and the lap rate is Since it is as low as 7 μm / hour or less, it is suitable for use in a magnetic head machining assembly jig.

In particular, Sample No. containing 5 to 10% by mass of magnesium phase titanium oxide. 2 to 4, 7 to 9, and 11 to 14 are suitable because the volume resistivity is stable at a level of 10 ⁸ Ω · cm and the lap rate is as low as 6 μm / hour or less.

Furthermore, sample no. Nos. 2 to 5 and 7 to 15 have a volume resistivity of 1 × 10 ⁶ to 1 × 10 ⁹ Ω · cm, so that the electric charge charged to the magnetic head can be gradually released and a conduction short circuit occurs. Nor.

  Sample No. 2 to 5 and 7 to 15 have a chromaticness index b * of −10 or less, and therefore can be easily distinguished from a magnetic head substrate made of an alumina-titanium carbide sintered body exhibiting black.

It is a schematic diagram which shows the structure | tissue structure of the alumina sintered compact of this invention. It is a schematic block diagram of the grinding | polishing apparatus used for grinding | polishing of the alumina sintered compact of this invention. It is a perspective view which shows the state which has arrange | positioned the alumina sintered compact of this invention to the grinding | polishing jig | tool. It is a perspective view which shows the transfer tool which is one Embodiment of the magnetic head processing assembly jig | tool of this invention. It is a perspective view which shows the use condition of the transfer tool which is one Embodiment of the magnetic head processing assembly jig | tool of this invention. It is a perspective view which shows the use condition of the tweezers which is one Embodiment of the magnetic head processing assembly jig | tool of this invention.

Explanation of symbols

1: Alumina sintered body 2: Alumina particles 3: Magnesium phase titanium oxide 4: Polishing device 5: Polishing disk 6: Polishing liquid 7: Container 8: Polishing jig 9: Transfer tool 10: Through hole 11: Magnetic head substrate 12: Lower surface 13: Upper surface 14: Tweezers

Claims (4)

An alumina sintered body comprising alumina as a main crystal phase and a grain boundary phase titanium oxide in the grain boundary phase. The alumina sintered body according to claim 1, wherein the magnesium phase titanium oxide is contained in an amount of 5 to 10% by mass. Magnetic head machining comprising the alumina sintered body according to claim 1 or 2, wherein the magnetic head substrate is held in a machining step or assembly step for producing a magnetic head from the magnetic head substrate. A magnetic head machining / assembly jig characterized by being an assembly jig having a volume resistivity of 10 ⁶ to 10 ⁹ Ω · cm. 4. The magnetic head machining assembly jig according to claim 3, wherein a chromaticness index b * in the CIE 1976 L * a * b * color space on the surface is −10 or less.

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