JP2006160599A - Lead-free glass composition and magnetic head - Google Patents

Abstract

A lead-free glass composition having a low fusing temperature and a magnetic head using the lead-free glass are provided.
Bi ₂ O ₃ : more than 70% and 78% or less, B ₂ O ₃ : 13 to 20%, ZnO: 5 to 7%, Na ₂ O: 0 to 5% , K ₂ O: 0 to 2%, P ₂ O ₅ : 0 to 4%, TeO ₂ : 0 to 4%, Sb ₂ O ₃ : 0 to 2%, Li ₂ O: 0 to 3%, SiO ₂ : A lead-free glass composition containing 0 to 6% and not containing PbO. A magnetic head is configured using this lead-free glass.
[Selection] Figure 1

Description

The present invention relates to a lead-free glass composition. More specifically, the present invention relates to a bonding glass for a magnetic head used for fusing ferrite or metal, for example, a bonding glass suitable for bonding a magnetic head.
Furthermore, the present invention relates to a magnetic head using the above lead-free glass.

  In a magnetic head using an amorphous magnetic metal as a magnetic core material, when the amorphous metal is heated to a temperature higher than the crystallization temperature, the magnetic characteristics deteriorate and the output decreases. In order to prevent this, it is necessary to heat at a temperature lower than the crystallization temperature of the amorphous metal, and when the glass is fused in the head manufacturing process, the glass must be fused at a temperature lower than the crystallization temperature. Looking at the margin, I want to keep the temperature 30 ° C lower than the crystallization temperature.

As an amorphous magnetic metal for a magnetic head, for example, Co aZr bNb cTa d (a, b, c, d are atomic%) 79 ≦ a ≦ 83
2 ≦ b ≦ 6
10 ≦ c ≦ 14
1 ≦ d ≦ 5
a + b + c + d = 100
The composition of the following is used. Since the crystallization temperature of such an amorphous magnetic metal is in the vicinity of 550 ° C., the fusion temperature of the magnetic head glass is preferably about 520 ° C. or less with a margin. Therefore, a glass for fusing used in a magnetic head using the above amorphous magnetic metal as a magnetic core material is required to have a fusing temperature of about 520 ° C. or lower.

Further, in a magnetic head that is processed through two or more glass fusion processes, the glass used for the second and subsequent fusions is at a temperature lower than the glass transition point of the glass used in the first glass fusion process. If it is not fused, remelting or the like of the fused portion fused at the first time occurs, and the magnetic head cannot be maintained within a predetermined dimension. As the first fused glass, it is desirable to use a glass having a fusion temperature of about 760 ° C. or less, which is difficult to change the pressure applied by the fusion jig, and its glass transition point is about 560 ° C. at the highest. Therefore, the glass used for the second glass fusing is required to have a fusing temperature of less than about 560 ° C.
Thus, in various magnetic heads, a glass that can be fused at a low temperature is required.

Furthermore, as a condition required for the fused glass, it is also important to adapt the thermal expansion coefficient with the magnetic core material. The thermal expansion coefficient of the glass is that of the oxide magnetic material or metal magnetic material (about 100 × 10 × 10). -7 to 140 × 10 −7 [° C. ⁻¹ ]), when the magnetic core is joined, residual stress is accumulated and glass cracks are likely to occur, and the glass is strong against compressive stress. Considering the above, it is preferable that the fused glass has a thermal expansion coefficient of about 90 × 10 −7 to 110 × 10 −7 [° C. ⁻¹ ], which is slightly smaller than the thermal expansion coefficient of the oxide magnetic material or the metal magnetic material. . However, generally, a glass having a low fusing temperature has a large coefficient of thermal expansion, and conversely, a glass having a high fusing temperature tends to have a low coefficient of thermal expansion. Therefore, it is necessary to change the composition to balance the two.

  On the other hand, the fused glass used for the magnetic head contains PbO for lowering the melting temperature, and contains a large amount of PbO when used at a lower temperature. Patent Document 1 discloses a glass composition for a magnetic head containing PbO. However, since lead is an environmental management substance, there are environmental problems and disposal problems, and there is a need for lead-free low-melting glass that does not contain lead. Further, like the lead-based glass, it is required to be able to control the thermal expansion coefficient and the fusing temperature depending on the material of the magnetic core, the place where the glass is fused, and the shape.

However, it is more difficult for lead-free glass to have a lower melting point than lead-based glass. P ₂ O ₅ -based lead-free glass has been disclosed in Patent Document 2 and the like, but cannot be formed into a rod shape with a very small wire diameter, cannot be glass unless the atmosphere is controlled, or crystals precipitate. Or
Japanese Patent Laid-Open No. 9-268023 JP 2001-199740 A

An object of the present invention is to provide a lead-free glass composition that satisfies the characteristics required for glass for a magnetic head and has no problems in the working environment and waste disposal.
Another object of the present invention is to provide a magnetic head using such lead-free glass.

In order to achieve the above-mentioned problems, the present inventors have focused on oxides such as Bi ₂ O ₃ , B ₂ O ₃ , and ZnO that have no problem in the working environment and waste disposal, and do not contain lead. The present inventors have found a stable glass composition having characteristics equivalent to or better.

That is, lead-free glass composition of the present invention, the oxide basis of weight percentages in _Bi 2 _O 3: 78% more than 70% or _{less, B 2 O 3: 13~20%} , ZnO: 5~7%, Na ₂ O: 0 to 5%, K ₂ O: 0 to 2%, P ₂ O ₅ : 0 to 4%, TeO ₂ : 0 to 4%, Sb ₂ O ₃ : 0 to 2%, Li ₂ O: 0 to _3%, SiO 2: consists of 6% of the composition, but containing no PbO.

Preferably, Bi ₂ O ₃ : 72 to 77%, B ₂ O ₃ : 14 to 20%, ZnO: 6 to 7%, Na ₂ O: 0 to 4%, TeO in terms of mass% based on oxide. _{2: 0~2%, Sb 2 O} 3: 0~2%, Li 2 O: consists _{0~2%, Na 2 O + TeO} 2 + Sb 2 O 3 + Li 2 O: that it is 0.5 to 4% A lead-free glass composition. Here, it is preferable that K ₂ O = 0%, P ₂ O ₅ = 0%, and SiO ₂ = 0%.

Bi ₂ O ₃ is a main component of the lead-free glass composition and has an effect of lowering the softening point and viscosity. This content is more than 70% and 78% or less (hereinafter,% means mass% unless otherwise specified). Bonding glass for magnetic heads is usually drawn in a rod shape, but if the Bi ₂ O ₃ content exceeds 78%, the glass becomes unstable and precipitates protrude from the glass surface during drawing. Therefore, if it is 70% or less, the working temperature becomes high and the wettability required by the present invention cannot be realized. A more preferable content of Bi ₂ O ₃ is in the range of 72 to 77%.

B ₂ O ₃ has an effect as a glass forming component, and its content is 13 to 20%. If the content of B ₂ O ₃ exceeds 20%, the fusing temperature becomes high, and if it is less than 13%, the glass becomes unstable and tends to devitrify. In consideration of sure prevention of devitrification, the more preferable content of B ₂ O ₃ is in the range of 14 to 20%.

  ZnO is a main component of lead-free glass and is effective in stabilizing the glass. This content is 5-7%. If the ZnO content exceeds 7%, the fusing temperature rises and wettability deteriorates, so that the wettability required by the present invention cannot be realized, and if it is less than 5%, the glass becomes unstable and tends to devitrify. . A more preferable content of ZnO is in the range of 6 to 7%.

Na ₂ O has an effect of accelerating the melting of the glass and lowers the fusing temperature. However, when contained in a large amount, the reliability of the glass is lowered and the thermal expansion is increased. Therefore, this content was 0 to 5%. When the content of Na ₂ O exceeds 5%, the water resistance of the glass is greatly lowered, and the glass becomes unstable and cannot be drawn. The preferable content of Na ₂ O is in the range of 0 to 4%, and the more preferable content of Na ₂ O that exhibits the effect is in the range of 0.5 to 4%.

Since K ₂ O is the same alkali metal oxide as Na ₂ O, it has an effect of lowering the fusion temperature. However, when it is contained in a large amount, the reliability of the glass is lowered and the thermal expansion is increased. This content is 0 to 2%. When the content of K ₂ O exceeds 2%, the water resistance of the glass is significantly lowered, and the glass becomes unstable and cannot be drawn.

P ₂ O ₅ forms a glass network structure. This content is 0-4%. If the content of P ₂ O ₅ exceeds 4%, the glass fusing temperature rises and wettability deteriorates, and the wettability required by the present invention cannot be realized. If vitrification without containing P ₂ O ₅ may not contain _P 2 _{O 5.}

TeO ₂ has an effect of improving water resistance and alkali resistance without relatively increasing the glass fusing temperature by substituting part of Bi ₂ O ₃ . This content is 0-4%. If the content of TeO ₂ exceeds 4%, the glass becomes unstable, and precipitates are likely to be generated in the glass at the time of fusion, so that the glass becomes poorly wet or cracks are formed in the precipitate. . The preferred content of TeO ₂ is in the range of 0-2%, preferably content than TeO ₂ is particularly effective is in the range of 0.5% to 2%.

Sb ₂ O ₃ has an effect of improving water resistance and alkali resistance without relatively increasing the glass fusing temperature by substituting part of Bi ₂ O ₃ . This content is 0 to 2%. If the content of Sb ₂ O ₃ exceeds 2%, the glass becomes unstable, and precipitates are likely to be generated in the glass at the time of fusing, resulting in poor wetting of the glass or cracks in the precipitation part. Or Preferred content of Sb ₂ O ₃ is in the range of 0-2%, preferably content than _Sb 2 _{O 3} is particularly effective is in the range of 0.5% to 2%.

Li ₂ O is the same alkali metal oxide as Na ₂ O and K ₂ O, and thus has an effect of lowering the fusion temperature. However, when contained in a large amount, the reliability of the glass is lowered and the thermal expansion is increased. This content is 0 to 3%. When the content of Li ₂ O exceeds 3%, the water resistance of the glass is greatly lowered, and the glass becomes unstable and cannot be drawn. The preferable content of Li ₂ O is in the range of 0 to 2%, and the more preferable content of Li ₂ O that exhibits the effect is in the range of 0.5 to 2%.

SiO ₂ forms a glass network structure. This content is 0-6%. If the SiO ₂ content exceeds 6%, the glass fusing temperature rises and wettability deteriorates, and the wettability required by the present invention cannot be realized. If vitrification without containing SiO ₂ may not contain SiO _2.

  The magnetic head of the present invention is constituted by using lead-free glass having the above composition as, for example, a gap filling material, a bonding material, and an insulating material of the head.

The magnetic head of the present invention can be configured by filling the narrow groove continuously restricting the gap depth so that the lead-free glass is not exposed on the sliding surface.
The magnetic head of the present invention is preferably applied to a magnetic head formed of a laminated film having an amorphous magnetic metal thin film as a magnetic core material.

  Fused glass with a composition in the above range can be fused at low temperatures if used as a gap filling material, bonding material, or insulating material for magnetic heads. Magnetic heads using amorphous magnetic metals and loose glass In order to prevent dimensional deviation due to the above, a high effect can be obtained by applying to a plurality of fusing steps of a magnetic head having a plurality of fusing steps that require fusing at as low a temperature as possible.

According to the lead-free glass composition according to the present invention, since it does not contain a lead component, it leads to an improvement of the working environment, and further has an effect that is not troublesome for waste disposal.
In addition, when used as a fused glass for magnetic heads, the glass of the present invention can be fused at a low temperature that does not cause crystallization of amorphous magnetic metal even though it does not contain a lead component. It is possible to manufacture a high performance magnetic head.
The lead-free glass composition according to the present invention can be drawn with a wire diameter of 0.15 mm ± 0.02 mm, for example, and can be suitably applied to the manufacture of a magnetic head.

According to the magnetic head of the present invention, since the lead-free glass described above is used, the working environment can be improved during manufacture, and the environment is not contaminated even during disposal.
In addition, according to the magnetic head according to the present invention, by using the lead-free glass described above that has been drawn, the narrowness that regulates the gap depth continuously to the winding groove so that the lead-free glass is not exposed to the sliding surface. A magnetic head filled in the groove can be provided.
In addition, when a lead-free glass having a fusing temperature lower than the crystallization temperature is used and a laminated film having an amorphous magnetic metal thin film as a magnetic core is formed, a high-performance amorphous metal laminated magnetic head can be provided. .

  Embodiments of the present invention will be described below.

  First, the lead-free glass composition according to the present embodiment will be described. Each component constituting the lead-free glass was mixed at a ratio shown in Table 1 (Example) and Table 2 (Comparative Example) and melted at 1100 to 1300 ° C., and then a drawing operation was performed to produce a rod-shaped lead-free glass. The unit is mass%. In addition, the glass mounted in the comparative example is the lead-free glass of the composition which remove | deviates from the claim of this invention, and the lead glass currently used.

About each glass obtained by Table 1, Table 2, the thermal expansion coefficient (100 to 350 degreeC), the glass transition point, and the fusion temperature were measured. The results are shown in Table 3. The fusing temperature represents a temperature at which the viscosity becomes 10 ³ Pa · sec.

Among the glasses of Examples obtained from the compositions shown in Table 1, all the samples 1 to 39 were vitrified, and no crystallization or devitrification was observed.
The coefficient of thermal expansion (at 100 ° C. to 350 ° C.) is 86 × 10 −7 to 118 × 10 −7 [/ ° C.], the glass transition point is 353 ° C. to 462 ° C., and the fusion temperature is 500 ° C. to 555 ° C. became.

The glass of the comparative example obtained from the composition of Table 2 is demonstrated.
Sample 40 is a conventional low-melting glass containing lead.
Sample 41 is lead-free glass, but the fusion temperature, which is the object of the present invention, is higher than 520 ° C. or less than 560 ° C., which is contrary to the spirit of the present invention.
Although the sample 42 is lead-free glass, the content of B ₂ O ₃ is less than 13%, and it is devitrified at the time of drawing and cannot be fused well.
Sample 43 is lead-free glass, but the content of B ₂ O ₃ is less than 13%, and the content of Bi ₂ O ₃ exceeds 78%. Precipitates protrude from the glass surface during drawing and melt well. I can't wear it.

Next, an embodiment of a magnetic head according to the present invention using the above glass composition as a reinforcing filler will be described with reference to the drawings.
FIG. 1 shows an embodiment in which a magnetic head according to the present invention is applied to an amorphous metal thin film laminated head. The magnetic head 1 according to the present embodiment is configured by arranging magnetic cores made of a laminated amorphous metal thin film 2 so that both surfaces are sandwiched between guard materials 8 made of, for example, nonmagnetic ceramic. That is, an amorphous metal magnetic thin film of Co ₈₁ Zr ₄ Nb ₁₂ Ta ₃ [atomic%] having a crystallization temperature of 550 ° C. and a non-magnetic thin film (for example, a Cr thin film) are alternately formed in a multilayer on a non-magnetic ceramic substrate serving as the guard material 8. The laminated amorphous metal thin film 2 is formed by sputtering. A pair of magnetic core halves 3L and 3R having the laminated amorphous metal thin film 2 are opposed to each other, and the surface of the metal magnetic thin film 2 is abutted through a gap film to form a magnetic gap portion g. The gap film is formed of, for example, gold (Au) and bonded by applying a pressure of 10 MPa and a temperature of 250 ° C. Further, the magnetic head 1 is constructed by inserting a glass rod for fusing into the magnetic gap g side in the winding groove 6, melting it, and filling it as the reinforcing glass 5. In this case, the drawn glass rod is inserted into the narrow groove 6 a that continues to the winding groove 6 and restricts the gap depth, and is finally filled as the fused glass 5. The fused glass 5 is not exposed to the sliding surface 9 of a magnetic recording medium, for example, a magnetic tape. The fused glass 5 reinforces the bonding between the magnetic core halves 3L and 3R. Further, a sliding surface 9 is formed by forming a curvature around the magnetic gap g. The fused glass 5 is provided on the front gap side and the back gap side. On the back gap side, the fused glass 5 is filled in the glass joining groove 7.

In the present embodiment, the glass of the example in Table 1 is used as the fusing glass 5, preferably glass having a melting temperature of 520 ° C. or less that does not crystallize the amorphous magnetic metal.
For example, the magnetic head of the present embodiment using the lead-free glass of the sample 37 of the example of Table 1 as the fused glass 5 and the magnetic head using the lead-containing glass of the sample 40 of the comparative example of Table 2 are manufactured. And compared. Compared with the magnetic head of the comparative example using the glass of the sample 40, the magnetic head 1 of the present embodiment using the lead-free glass of the sample 37 shows no problems in electrical characteristics and work process, and is lead-free. Magnetic heads similar to lead glass could be fabricated using glass.

FIG. 2 is a specific example of the amorphous metal thin film laminated head of FIG. The magnetic head 11 according to the present embodiment is configured such that the step 10 is formed so as to narrow the contact width of the sliding surface 9 with the magnetic tape so that the head contact with the magnetic tape is good. Further, a notch 12 for winding is formed on both sides of the magnetic core together with the guard material 8, and the coil 13 is wound through the notch 12 and the winding groove 6. Since the other configuration is the same as that of FIG. 1, the same reference numerals are given and redundant description is omitted.
Even in this configuration, the lead-free glass shown in the examples of Table 1, preferably the lead-free glass having a fusion temperature of 520 ° C. or less at which the amorphous magnetic metal does not crystallize, the amorphous metal magnetic thin film does not crystallize and is drawn. Thus, the glass 5 can be filled in the narrow groove 6a on the gap G side, and a high-performance magnetic head considering the environment can be provided.

FIG. 3 shows another embodiment in which the magnetic head according to the present invention is applied to a metal-in-gap (MIG) type magnetic head. In the magnetic head 21 according to the present embodiment, a crystalline metal magnetic thin film 23 having a high magnetic permeability is formed on the abutting surfaces of the ferrite core halves 22L and 22R, and a magnetic film is interposed between the crystalline metal magnetic thin films 23 via a gap film. The two ferrite core halves 22L and 22R are joined to form the gap g. In this case, the lead glass 24 having high reliability (evaluated by alkali resistance) is used for the fusing glass provided on the front gap side exposed on the sliding surface 26, and the fusing glass provided on the back gap side is represented by 1, lead-free glass 25 having a low fusing temperature is used. These two different types of lead-free glasses 24 and 25 are fused simultaneously. The front gap side has a short glass flow distance, and the back gap side has a long glass flow distance. For this reason, the lead-free glass 24 on the front gap side exposed to the sliding surface 26 is a highly reliable glass (having a high fusion temperature), for example, the sample 41 of the comparative example in Table 2, but is not exposed to the sliding surface. When the lead-free glass 25 on the back gap side is a lead-free glass having a low fusing temperature shown in Table 1, for example, the sample 2 of the example, it can be fused over a long distance and reliable bonding can be performed.
According to the magnetic head 21 of the present embodiment, it is possible to provide a MIG type magnetic head that is highly reliable, suitable for a recording head, and environmentally friendly.

FIG. 4 shows another embodiment in which the magnetic head according to the present invention is applied to a magnetic head for a data cartridge. The magnetic head 31 according to the present embodiment is constituted by joining three magnetic core members with a fused glass through a gap film, and having a reproduction gap g1 and a recording gap g2. In this magnetic head 31, first, the first and second ferrite cores 34A and 34B of the ferrite head 34 on the reproduction gap g1 side are made of, for example, SiO ₂ : 48.0 wt%, B ₂ O ₃ : 18.0 wt%, Na High melting point lead-free glass 36 having a composition of ₂ O: 12.0 wt%, BaO: 12.0 wt%, Fe ₂ O ₃ : 5.6 wt%, ZnO: 4.4 wt% (coefficient of thermal expansion 90 × 10 −7 / And a glass transition point of 560 ° C. at a high temperature (760 ° C.). The reason why the glass having the above composition is used as the first fusing glass 36 on the ferrite head 34 side is that the dimensional accuracy after fusing is regarded as important, so that the fusing jig is not deteriorated (about 760 ° C. or less). It has a deposition temperature, but also has a glass transition point as high as possible in consideration of the second and subsequent fusions (MIG side fusion), and further has a low erosion diffusion reaction to ferrite and the like. Because.

Next, the glass of the example in Table 1 having a melting temperature lower than the glass transition point (560 ° C.) of the glass composition, for example, sample 1 in Table 1 (fusion temperature 545). The recording-side gap g2 is fused using a lead-free low-melting glass 37 at a temperature of ° C. That is, the second ferrite core 34B and the third magnetic core 34C in which the high permeability crystalline metal magnetic film 39 is formed on the gap surface side of the ferrite core 38 are joined using the lead-free glass 37 for recording. The gap g2 is formed, and the MIG head 35 is formed.
If the lead-free low-melting glass of Sample 1 in Table 1 is used as the fusing glass 37 on the MIG head 35 side, fusing can be performed at a low temperature so as not to loosen the glass 36 on the reproduction gap g1 side.

  According to the magnetic head 31 of the present embodiment, it is possible to provide a highly reliable composite magnetic head including a recording head and a reproducing head that have two glass fusing steps. In addition, since the glass used in the two fusion processes is lead-free glass, it becomes a magnetic head considering the environment.

1 is a configuration diagram showing an embodiment of a magnetic head according to the present invention. FIG. 2 is a configuration diagram illustrating a specific embodiment of the magnetic head according to FIG. 1. It is a block diagram which shows other embodiment of the magnetic head based on this invention. It is a block diagram which shows other embodiment of the magnetic head which concerns on this invention.

Explanation of symbols

1, 11, 21, 31 ... Magnetic head 2. Laminated amorphous metal magnetic thin film 3L, 3R ... Magnetic core half, g ... Magnetic gap, 5 .... Fused glass, 6 .... Winding groove 6a ··· Narrow groove, 7 ··· Glass joint groove, 8 · · Guard material, 9 · · Sliding surface 10 · · Step, 12 · · Notch, 13 · · Coil, 22L. 22R ... Ferrite core, 23 ... Crystalline metal magnetic film, 24, 25 ... Lead-free glass, 26 ... Slide surface, 34 ... Ferrite head, 34A, 34B ferrite core, 34C ... Magnetic core, 35 ... MIG head, 36 ·· first fused glass, 37 ·· second fused glass, 38 ·· ferrite core, 39 ·· crystalline metal magnetic thin film

Claims (5)

_Bi 2 _O 3 in mass% based on oxide: 78% greater than 70% or _{less, B 2 O 3: 13~20%} , ZnO: 5~7%, Na 2 O: 0~5%, K 2 O _{: 0~2%, P 2 O 5} : 0~4%, TeO 2: 0~4%, Sb 2 O 3: 0~2%, Li 2 O: 0~3%, SiO 2: 0~6% A lead-free glass composition comprising: Bi ₂ O ₃ : 72 to 77%, B ₂ O ₃ : 14 to 20%, ZnO: 6 to 7%, Na ₂ O: 0 to 4%, TeO ₂ : 0 to 2 in terms of mass% based on oxide %, Sb ₂ O ₃ : 0 to 2%, Li ₂ O: 0 to 2%,
The lead-free glass composition according to claim 1, wherein Na ₂ O + TeO ₂ + Sb ₂ O ₃ + Li ₂ O: 0.5 to 4%. A magnetic head comprising the lead-free glass according to claim 1. The magnetic head according to claim 3, wherein the lead-free glass is filled in a narrow groove that continuously restricts the gap depth so that the lead-free glass is not exposed to the sliding surface. The magnetic head according to claim 4, wherein the magnetic core is formed of a laminated film having an amorphous magnetic metal thin film.

Images