JP4276129B2 - Glass composition for magnetic head and magnetic head - Google Patents

Description

  The present invention relates to a magnetic head suitable for recording / reproducing magnetic information on a magnetic recording medium, and relates to a glass for a magnetic head constituting the magnetic head.

In recent years, it has been desired that a magnetic head can form a magnetic gap at a lower temperature in terms of preventing deterioration of magnetic characteristics.
In general, a magnetic head is formed by providing a very narrow gap (magnetic gap) between a pair of high magnetic permeability magnetic bodies wound with a coil. This magnetic gap is formed by a nonmagnetic material (gap material) on the opposing surface of the high permeability magnetic body, and the gap materials are joined together.

Moreover, in the magnetic head for a video tape recorder, as a high permeability magnetic body, an oxide material such as Mn-Zn ferrite, an oxide material such as Mn-Zn ferrite or ceramics and a metal magnetic thin film are combined, etc. in use. Further, as the gap material, nonmagnetic metal, metal oxide, glass or the like is used.
As a method of forming a magnetic gap, a gap material is formed into a thin film by sputtering or vapor deposition on the surface of a high permeability magnetic material to form a pair of magnetic core halves, and the pair of magnetic core halves There is a method of joining the gap materials together.

The joining of the magnetic core halves is performed at a temperature at which the gap members are fused. At this time, if fusion is performed at a high temperature, the characteristics of the high magnetic permeability magnetic body and the deformation of the gap material occur, and the magnetic head characteristics deteriorate. Therefore, in order to prevent the occurrence of magnetic characteristic deterioration due to high temperature, there is generally a gap material shown in FIG. FIG. 4 is an enlarged view of a main part showing a magnetic gap portion of a conventional magnetic head. As shown in FIG. 4, an arbitrary nonmagnetic material layer 9 is laminated at least on the first layer and a low-melting glass layer 10 is laminated on the second layer, and the glass layers 10 are thermally melted together. A method of joining by adhesion and forming a magnetic gap is used (see, for example, Patent Document 1).
As the glass used for this magnetic head, a PbO—SiO ₂ system, a SiO ₂ —B ₂ O ₃ —ZnO system, and the like have been developed (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 9-219009 Japanese Patent No. 3173134

However, the conventional glass is a low softening point glass, but the content of B ₂ O ₃ is small and the change in viscosity with temperature is small. Therefore, if the temperature is not much higher than the softening point, it is necessary for bonding. It did not drop to viscosity. For this reason, there is a problem that the heat treatment temperature for bonding needs to be about 100 to 150 ° C. higher than the softening point, and the characteristics of the magnetic material deteriorate due to the high temperature.

As described above, at least the first magnetic layer 8 is laminated with the nonmagnetic material layer 9 and the second layer is the glass layer 10, and the second glass layer 10 is bonded to the high permeability magnetic body 8 by heat fusion. When a conventional PbO—SiO ₂ or SiO ₂ —B ₂ O ₃ —ZnO glass is used for the glass layer 10 in a magnetic head having a magnetic gap formed by bonding, the magnetic gap is formed at a high temperature. There is a problem that the magnetic properties are deteriorated due to high temperature.

  The present invention has been made in view of the conventional situation, and an object of the present invention is to provide a glass composition for a magnetic head and a magnetic head capable of preventing deterioration of magnetic characteristics due to a high temperature when forming a magnetic gap. .

In order to solve the above problems, the present inventor paid attention to the oxide of B ₂ O ₃ , and as a result of earnest research, by increasing the content of B ₂ O ₃ than the conventional glass, The change was increased, and the viscosity required for bonding was obtained at a temperature close to the softening point. For this reason, the heat treatment temperature can be increased at a temperature as low as 30 to 60 ° C. above the softening point, and the magnetic properties were not deteriorated by the high temperature, and other properties were found to have an equivalent glass composition. Other characteristics are thermal expansion coefficient, reactivity with magnetic materials, and bonding strength.

The invention corresponding to claim 1 of the present invention is a glass composition for a magnetic head, wherein the SiO _{2 is 2 to} 30%, B ₂ O _{3 is} 32 to 68%, ZnO is 8 in terms of mass% based on oxide. _{.3~47%, Al 2 O 3:} 0.5~21%, R 2 O: 1~20%,: a _(R 2 O at least one selected from _{Li 2 O, Na 2 O,} K 2 O) It is characterized by containing.
Accordingly, it is possible to provide a glass composition for a magnetic head and a magnetic head, which can prevent the deterioration of magnetic characteristics due to a high temperature when forming a magnetic gap, and which are excellent in terms of bonding strength. .

As described above, the glass composition for a magnetic head of the present invention can increase the content of B ₂ O ₃ , keep the heat treatment temperature for the softening point low, and form a magnetic gap without deteriorating magnetic properties. it can.

Glass compositions for a magnetic head of the present invention is represented by mass% based on _{oxide, SiO 2: 2~30%, B} 2 O 3: 29~68%, ZnO: 8.3 ~47%, Al 2 O ₃ : 0.5 to 21%, R ₂ O: 1 to 20%, (R ₂ O: at least one selected from Li ₂ O, Na ₂ O, K ₂ O) Is.

Furthermore, MgO, CaO, SrO, BaO, ZrO ₂ , Fe ₂ O ₃ , NiO, MoO ₃ , WO ₃ , TeO ₂ , Bi are used in the range of 0 to 5% in order to adjust the viscosity and thermal expansion coefficient of the glass. ₂ O ₃ , Ag ₂ O and the like can be added. And the raw material was prepared so that it might become the said composition, and it was set as the raw material batch. This batch raw material was put into a platinum crucible, heated and melted for 1 to 3 hours in an electric furnace at 1100 to 1400 ° C., and then poured onto an iron plate or a mold to obtain a glass block. The glass block is gradually cooled and then cut and polished to form a glass plate, glass rod or square bar having a predetermined shape. Alternatively, after the glass block after slow cooling is cut, it is redrawn and formed into a glass rod or square bar having a predetermined shape.

As described above, (Table 1) shows an example of the glass composition according to claim 1 of the present invention. The reason why the range of the content of each component is limited as described above will be described in detail in Examples.
In addition, about components other than the structural component in the above glass composition, it can add for a certain kind of modification | change in the range which does not impair the effect of this invention.
Hereinafter, although embodiment of the glass composition of this invention is described, this invention is not limited by these.

As described in Example 1 of Table 1, SiO ₂ : 18%, B ₂ O ₃ : 38%, ZnO: 15%, Al ₂ O ₃ : 12%, Na ₂ O: 17% In addition, the raw materials are blended into batch raw materials. The batch raw material was put in a platinum crucible and heated and melted in an electric furnace at 1300 ° C. for 2 hours, and then poured onto an iron plate to form a glass block, which was gradually cooled overnight.
The properties of the glass thus obtained were measured as follows. Glass transition point and softening point: A part of the glass block was cut out, and this glass lump was made into powder of 100 mesh or less. And when each temperature was measured with the temperature increase rate of 10 degree-C / min using the differential thermal analyzer, they were the transition point 472 degreeC and the softening point 552 degreeC.

  Heat treatment minimum temperature: Sputtered glass is used as a test piece on the surface of a ferrite single crystal plate finished in a mirror state, and the two sputtered surfaces of the above test pieces facing each other are stacked on a cast iron jig. It was heated and cooled under a predetermined temperature condition in a state where a pressure of 0.4 MPa was applied. At this time, the heating ultimate temperature of the test piece was set at intervals of 10 ° C. from the softening point. After heating and cooling, the two test pieces welded to each other were peeled off and observed with an optical microscope. The lowest temperature at which the interface of the glass sputtered on the two test pieces disappeared due to the softening of the glass was defined as the lowest heat treatment temperature. As a result, the lowest processing temperature was 595 ° C. Therefore, since the heat treatment temperature is 750 ° C. or lower, sealing can be performed without deteriorating the magnetic properties of the magnetic material.

Thermal expansion coefficient: When cut out from a glass block, it was processed into a size of 5φ × 20 mm, and an average thermal expansion coefficient from 30 to 300 ° C. was measured at a temperature rising rate of 10 ° C./min using a differential dilatometer. 99 × 10 ⁻⁷ / ° C.

  Glass stability: Cut out from glass block, molded into 0.5 × 0.5 × 30 mm glass rod, heat-treated at 750 ° C. for 1 hour while placed on alumina substrate, and cooled to room temperature The glass surface was observed with a 50 × optical microscope. As a result, no precipitation of crystals was observed. Therefore, it is possible to prevent a decrease in sealing strength due to crystal precipitation and a change in the thermal expansion coefficient. As described above, the glass itself can be sufficiently sealed by heat treatment at about 595 ° C., but in this evaluation, the glass was evaluated at a high temperature that does not cause deterioration of the magnetic properties of the magnetic material.

  Reactivity with ferrite: Cut out from glass block, processed to 3 × 3 × 10 mm size, and placed on single-crystal ferrite finished in mirror surface, softening point + 100 ° C. for 1 hour The heat treatment was performed. Then, after cooling to room temperature, the cross section of glass and ferrite was polished and the interface was observed with a 500 times optical microscope. As a result, no corrosion occurred on the ferrite surface due to the reaction with glass. Therefore, even if sealing is performed using this glass, the magnetic properties of the magnetic material do not deteriorate.

As described in Examples 2 to 8 in Table 1, the raw materials were mixed to form a batch raw material with a platinum crucible and melted under the melting conditions described in Table 1, and then as in Example 1, After casting on an iron plate to form a glass block, it was cooled overnight.
And when the sample for characteristic evaluation was created from this glass block similarly to the said Example 1, and it evaluated, the glass transition point was 443-525 degreeC, and the softening point became 517-630 degreeC. Since the minimum temperature of the heat treatment is 30 to 50 ° C. higher than the softening point, the magnetic core half can be bonded and the nonmagnetic substrate and the metal magnetic film can be bonded without deteriorating the magnetic properties of the magnetic material. it can.
Further, the thermal expansion coefficient is 45 to 124 × 10 ⁻⁷ / ° C., and the magnetic core half can be bonded and the nonmagnetic substrate and the metal magnetic film can be bonded.

In the evaluation of the glass stability, all samples were observed with a 50 × optical microscope, but no crystals were precipitated. Therefore, even if a magnetic material is sealed using these glasses, the sealing strength is not lowered and the function of the magnetic head is not impaired.
In the evaluation of reactivity with ferrite, the interface between the glass and ferrite of all the samples was observed with a 500-fold optical microscope, but no erosion due to reaction with the glass occurred on the ferrite surface. Therefore, even if a magnetic material is sealed using these glasses, the magnetic properties are not deteriorated.

Comparative Example 1 is an example of PbO—SiO ₂ glass and the content of B ₂ O ₃ is 4.5%. Comparative Example 2 is SiO ₂ —B ₂ O ₃ —ZnO glass and contains B ₂ O ₃ . The amount is 21%. As can be seen from this comparative example, when the B ₂ O ₃ content in the glass composition for a magnetic head is small, the change in viscosity due to temperature is small, so the minimum temperature for heat treatment is about 100 ° C. higher than the softening point of the glass. Must.

Here, the reason for limitation of each component which comprises this invention is shown below. B ₂ O ₃ is a main component of the glass composition, and has the effect of increasing the viscosity change with temperature and reducing the viscosity to a heat treatable temperature near the softening point. The content is 29 to 68% (hereinafter, “%” means “mass%” unless otherwise specified), preferably 32 to 67%. If the content of B ₂ O ₃ exceeds 68%, the softening temperature of the glass becomes high and heat treatment at a predetermined temperature becomes difficult. On the other hand, if it is less than 29%, the effect of the glass lowering the heat treatment temperature is lost.

SiO ₂ has an effect of suppressing the reaction with the magnetic material and an effect of improving the chemical durability of the glass. Its content is 2-30%, preferably 8-28%. When the SiO ₂ content exceeds 30%, the softening temperature becomes high, and heat treatment at a predetermined temperature becomes difficult. If it is less than 2%, the effect of suppressing the reaction with the magnetic material and the effect of improving the chemical durability of the glass are lost. Further, the glass becomes unstable and is easily crystallized.

ZnO is effective in stabilizing the glass, and its content is 8.3 to 47%, preferably 8.3 to 40%. If the ZnO content exceeds 47%, crystallization is likely to occur and a stable glass cannot be obtained. If it is less than 8.3 %, there is no effect in stabilizing the glass.

Al ₂ O ₃ is effective in improving and stabilizing the chemical durability of the glass, and its content is 0.5 to 21%, preferably 1 to 16%. If the content of Al ₂ O ₃ exceeds 21%, the softening temperature becomes high, and heat treatment at a predetermined temperature becomes difficult. If it is less than 0.5%, the chemical durability of the glass is not improved and stabilized.

R ₂ O, that is, at least one alkali metal oxide selected from Li ₂ O, Na ₂ O, and K ₂ O has an effect of lowering the softening temperature of the glass. The content thereof is 1 to 20%, preferably 2 to 18%, based on the entire R ₂ O. When the content of R ₂ O exceeds 20%, the crystallization tendency during heat treatment is remarkably increased, and a stable glass cannot be obtained. If it is less than 1%, there is no effect of lowering the softening temperature of the glass. The Li ₂ O content is 0 to 15%, preferably 0 to 10%, the Na ₂ O content is 0 to 20%, preferably 0 to 19%, and the K ₂ O content is 0 to 15%. %, Preferably 0 to 8%. If the content of each component exceeds the above range, a stable glass cannot be obtained.

In addition to the above components, MgO, CaO, SrO, BaO, ZrO ₂ , Fe ₂ O ₃ , NiO, MoO ₃ , in the range of 0 to 5% for adjusting the viscosity and thermal expansion coefficient of glass, etc. WO ₃ , TeO ₂ , Bi ₂ O ₃ , Ag ₂ O and the like can be added.

If MgO, CaO, SrO, BaO, ZrO ₂ , Fe ₂ O ₃ , NiO, MoO ₃ , WO ₃ , TeO ₂ , Bi ₂ O ₃ , Ag ₂ O, etc. contain more than 5%, crystallization occurs during the heat treatment. It becomes easy. If BaO is contained in an amount exceeding 5%, water resistance is deteriorated and harmful water-soluble BaO is easily eluted, which is not preferable. If the component to be colored such as Fe ₂ O ₃ , NiO, MoO ₃ , WO ₃ exceeds 5%, the coloring of the glass becomes strong, and it becomes difficult to measure the gap depth using an optical microscope or the like. It is not preferable.

  When the temperature of the magnetic material exceeds 750 ° C., the magnetic properties deteriorate, so it is necessary to perform heat treatment at a low temperature. When the glass composition of the present invention is used for bonding and adhesion to a magnetic head material, it can be heat-treated at a softening point +30 to 50 ° C. as well as heat treatment at 750 ° C. or lower. For this reason, it can be used for bonding a gap or bonding a nonmagnetic substrate and a metal magnetic film without deteriorating magnetic properties.

  The thermal expansion coefficient of the glass composition of the present invention is close to that of the magnetic material, does not react with the magnetic material, and the glass is stable and does not crystallize in the heat treatment step. Therefore, if this glass composition is molded into, for example, a glass rod or square bar having a predetermined shape and size and subjected to a heat treatment at a softening point of +30 to 50 ° C., it can be used for bonding and bonding of magnetic materials for magnetic heads. Can do.

The above glass composition for a magnetic head can be used for manufacturing a magnetic head in the form of bulk, powder, fiber, thin film or the like. Other shapes may be used. Furthermore, these glass compositions for magnetic heads can be used as a material composed of the glass composition alone or as a composite material of the glass composition and other materials.
Moreover, these glass compositions for magnetic heads are used as a material having a thermal expansion coefficient exceeding the range of 45 × 10 ^{−7 to} 124 × 10 ⁻⁷ / ° C. when used as a composite material with other materials. Can be used.

  FIG. 1 shows an example of a magnetic head according to a second aspect of the present invention, in which a pair of magnetic core halves 3 and 4 provided with winding grooves on at least one side are interposed via a magnetic gap 2. A magnetic head having a butted and bonded structure, in which a pair of magnetic core halves 3 and 4 are bonded by a bonding glass 1. The bonded glass 1 in FIG. 1 is as shown in claim 1.

Hereinafter, embodiments of the magnetic head according to the second aspect of the present invention will be described, but the present invention is not limited thereto.
First, the magnetic core halves 3 and 4 were formed by sputtering the nonmagnetic material SiO ₂ as the gap material and the glass of Example 1 as the bonding glass 1 into the Mn—Zn single crystal ferrite magnetic material formed into a predetermined shape. Next, the magnetic core halves 3 and 4 are brought into contact with each other, held by a jig, and then bonded at 595 ° C. Further, the outer shape was processed into predetermined dimensions and shapes to complete the magnetic head.

  FIG. 2 shows an example of a magnetic head according to a third aspect of the present invention, in which a pair of magnetic heads in which a winding groove is provided in at least one and a metal magnetic film 5 is formed in at least one magnetic gap portion. A magnetic head having a structure in which the core halves 3 and 4 are abutted and bonded via the magnetic gap portion 2, and the pair of magnetic core halves 3 and 4 are bonded by the bonding glass 1. . The bonded glass of FIG. 2 is as shown in claim 1.

Hereinafter, embodiments of the magnetic head of the present invention will be described, but the present invention is not limited thereto.
First, sputtering molded Mn-Zn single crystal ferrite magnetic material into a predetermined shape, using the Fe-Ta-N film as the metallic magnetic film, SiO ₂ in a non-magnetic material as a gap material, the glass of Example 1 in bonding glass Thus, magnetic core halves 3 and 4 were prepared. Next, the magnetic core halves 3 and 4 are brought into contact with each other, held by a jig, and then bonded at 595 ° C. Further, the outer shape was processed into predetermined dimensions and shapes to complete the magnetic head.

In order to confirm the bonding strength of the magnetic core halves 3 and 4 of the magnetic head thus obtained, measurements were performed as follows.
Bonding strength: measured by a three-point bending method. The central part of the magnetic head was supported at two points horizontally at an interval of 1 mm, a load was applied from the top to the center between the two support points at a speed of 1 mm / min from the top, and the strength was calculated from the load at which the magnetic head was broken. . Of the measured values of 12 magnetic heads, the average value of 10 measured values excluding the maximum value and the minimum value was taken as the bonding strength of the magnetic head, which was 214 MPa.

  FIG. 3 shows an example of the magnetic head according to claim 4 or claim 5 of the present invention, wherein a winding groove is provided in at least one, and the metal magnetic film 5 is sandwiched between nonmagnetic substrates 6. A magnetic head having a structure in which a pair of magnetic core halves 3 and 4 in which at least one of the non-magnetic substrate 6 and the metal magnetic film 5 are bonded with an adhesive glass 7 are butted and bonded via a magnetic gap 2; The pair of magnetic core halves 3 and 4 are joined by the joining glass 1. In the magnetic head according to claim 4 of the present invention, the bonding glass 1 of FIG. 3 is as shown in claim 1. Further, in the magnetic head according to claim 5 of the present invention, the adhesive glass 7 of FIG. 3 is as shown in claim 1.

Hereinafter, embodiments of the magnetic head according to claim 5 of the present invention will be described, but the present invention is not limited thereto.
First, a Co—Nb—Ta—Zr film 5 is formed by sputtering on a mirror-finished Ti—Mg—Ni sintered substrate 6, and the glass of Example 8 is similarly formed as an adhesive glass 7 continuously. A film was formed by sputtering.

  The Ti—Mg—Ni sintered substrate 6 on which the metal magnetic film 6 and the adhesive glass 7 are sputtered and the Ti—Mg—Ni sintered substrate on which nothing is formed are stacked and held under pressure at 665 ° C. The metal magnetic film 5 was sandwiched between the nonmagnetic substrates 6 and bonded.

Furthermore, the blocks of laminated and adhered to the substrate material as described above, SiO _2, was sputtered glass of Example 1 as a bonding glass 1, molded magnetic core half 3 by machining a nonmagnetic layer as the gap material 4 was created. Next, the magnetic core halves 3 and 4 are brought into contact with each other, held by a jig, and then bonded at 595 ° C. Further, the outer shape was processed into predetermined dimensions and shapes to complete the magnetic head.

  Since the magnetic head of the present embodiment as described above is not easily crystallized in the heat treatment process at the time of sealing and uses the glass composition for a magnetic head of the present invention having excellent glass stability, electromagnetic conversion It can be supplied as a magnetic head having excellent characteristics. Further, the bonding strength is equivalent to the conventional one as shown in (Table 1).

  Note that conventional materials can be basically used for the high magnetic permeability magnetic material and the magnetic gap material in the magnetic head described above. The glass composition for a magnetic head in the present invention can also be used for a magnetic head having a structure other than the above magnetic head.

  The glass composition of the present invention is used in various applications including various parts for electronic devices as adhesive materials, sealing materials, coating materials, or paste materials having various functions such as ceramics, glass and metal. It can be used in place of a conventionally used glass material. For example, it can be used for display devices such as various LCR components, semiconductor packages, other electronic components, CRTs, fluorescent display tubes, plasma display panels, and the like. Further, it can also be used in tube products for lighting, enamel products, ceramic products and the like.

The perspective view which shows the outline of the magnetic head by embodiment of this invention The perspective view which shows the outline of the magnetic head by embodiment of this invention The perspective view which shows the outline of the magnetic head by embodiment of this invention Enlarged view of the main part showing the magnetic gap part of a conventional magnetic head

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bonding glass 2 Magnetic gap 3 Magnetic core half body 4 Magnetic core half body 5 Metal magnetic film 6 Nonmagnetic board | substrate 7 Adhesive glass 8 High permeability magnetic body 9 Nonmagnetic body layer 10 Glass layer

Claims (5)

SiO ₂ : 2 to 30%, B ₂ O ₃ : 32 to 68%, ZnO: 8.3 to 47%, Al ₂ O ₃ : 0.5 to 21%, R ₂ O : A glass composition for a magnetic head, comprising 1 to 20%, (R ₂ O: at least one selected from Li ₂ O, Na ₂ O, K ₂ O ) and not containing PbO. A pair of magnetic core halves having a groove on at least one winding, via a formic cap member, a magnetic head having a junction structure, the pair of magnetic core halves according to Claim 1 A magnetic head, which is bonded with a glass composition for a magnetic head. A pair of magnetic core halves having a winding groove on at least one, via a gap material, a magnetic head having a junction structure, the metal magnetic on at least one surface of the pair of magnetic core halves A magnetic head , comprising a film, wherein the pair of magnetic core halves are bonded with the glass composition for a magnetic head according to claim 1. A magnetic head having a structure in which a pair of magnetic core halves formed by providing a winding groove in at least one and sandwiching a metal magnetic film between nonmagnetic substrates via a nonmagnetic gap material, magnetic head is characterized in that the magnetic core halves are joined with a glass composition for a magnetic head according to claim 1.   A magnetic head having a structure in which a pair of magnetic core halves obtained by providing a winding groove in at least one and sandwiching a metal magnetic film between nonmagnetic substrates via a gap material, A magnetic head, wherein the metal magnetic film is bonded with the glass composition for a magnetic head according to claim 1.