JP2008176861A - Magnetic head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic head employing a lead-free glass composition having no problem in a work environment and disposal processing while securing fusion bonding strength and wear resistance of the magnetic head and to provide its manufacturing method. <P>SOLUTION: The magnetic head 31 is composed by fusion-bonding of a pair of magnetic cores by sheets of glass 34 and 35 via a gap material, wherein the pair of magnetic cores are bonded by using unleaded glass having ≤7.3×10<SP>-6</SP>mm<SP>2</SP>wear area by a regulated wear test as the glass 34 appearing in a sliding surface on a front side 36 and nonleaded glass having a glass transition temperature lower than that of the glass 34 on the front side 36 by 15 to 25°C as the glass 35 on a back side 37. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a magnetic head using a lead-free glass composition.
More specifically, it relates to a combination of lead-free bonding glass for magnetic heads used for fusion of ferrite or metal, for example, a magnetic head combined with lead-free bonding glass suitable for gap formation and bonding of magnetic heads is there.
Furthermore, this invention relates to the manufacturing method of the magnetic head using the said lead-free glass composition.

  In general, a magnetic head is formed by bonding and integrating magnetic cores made of an oxide magnetic material such as Mn-Zn ferrite or a composite of these oxide magnetic material and a metal magnetic thin film such as Sendust using bonding glass. Composed. For example, the working gap part of a magnetic head can be obtained by heating and melting a bonding glass drawn in a rod shape to a working high temperature above the melting point, pouring it between magnetic cores, and then cooling the glass between these magnetic cores. It is configured by fusing.

Such bonding glass is required to have severe characteristics in terms of water resistance, corrosion resistance, wear resistance, bonding strength, and the like, and since it can be drawn in a rod shape, a bonding glass mainly composed of PbO, SiO ₂ or the like has been proposed. (For example, refer to Patent Document 1).

As described above, the conventional fused glass contains lead oxide PbO in order to lower the melting point. However, since lead is an environmental management substance, there are environmental problems and disposal problems. A low-melting-point glass not containing a system component has been demanded and developed (for example, Patent Document 2).
On the other hand, in order to achieve high-density recording, not only magnetic powder coating type but also vapor deposition type has come out and various types of tape sliding lubricants are used accordingly. Of these, lubricants with high abrasiveness are also used. When such a magnetic tape slides on the magnetic head, there is a problem that the glass exposed on the sliding portion of the magnetic head is unnecessarily polished to cause a step in the sliding portion of the magnetic head. Since the electromagnetic conversion characteristics cannot be secured, a glass having excellent wear resistance is required.

JP 61-101432 A JP 2006-225255 A

In the case of a metal-in-gap head using a magnetic core made of a composite of an oxide magnetic material and a metal magnetic thin film, the characteristics of the metal magnetic thin film deteriorate if the fusion temperature is high. It is necessary to make the fusion temperature as low as possible.
However, as described in the background art, a glass having excellent wear resistance is required for the sliding surface of the magnetic head corresponding to the magnetic tape for high-density recording, which satisfies such wear resistance. In order to sufficiently fuse the magnetic core half with lead-free glass, it often has to be fused at a high temperature exceeding 600 ° C.

  As mentioned above, low melting and high wear resistance of glass is a contradictory dilemma, and if high wear resistant glass is flowed at a low temperature that is less than necessary, giving priority to low melting, the distance that the glass flows is short. The necessary bonding strength of the head gap cannot be ensured.

  In view of the above-mentioned points, the present invention provides a magnetic head using a lead-free glass composition that has no problem in the working environment and disposal while ensuring sufficient fusion bonding strength and wear resistance of the magnetic head. The purpose is to provide. Another object of the present invention is to provide a method of manufacturing a magnetic head using such a lead-free glass.

  In order to achieve the above-mentioned problems, the present inventors have made a lead-free glass having a high fusing temperature and difficult to flow but having sufficient wear resistance, and a lead-free glass having a suitable fusing temperature that is inferior in wear resistance. In combination, we devised a magnetic head in which the former was placed on the front side and the latter on the back side. We also devised a method of manufacturing a magnetic head in which these two glasses are fused and bonded simultaneously under the same conditions.

That is, the magnetic head of the present invention is a magnetic head in which a pair of magnetic cores are fusion-bonded with glass via a gap material, and has a wear area by a specified wear test as glass that appears on the sliding surface on the front side. The magnetic core is bonded using lead-free glass of 7.3 × 10 ⁻⁶ mm ² or less and lead-free glass whose glass transition point is 15 to 25 ° C. lower than that of the front glass as the back glass. It is characterized by.

  In the magnetic head of the present invention, a sufficient gap bonding strength can be ensured and a sliding surface with excellent wear resistance can be obtained.

The magnetic head manufacturing method of the present invention is a method for manufacturing a magnetic head in which a pair of magnetic cores are fusion-bonded with glass via a gap material. As the front side glass, lead-free glass having a wear area of 7.3 × 10 ⁻⁶ mm ² or less is used according to the specified wear test, and the back side glass has a glass transition point of 15 than that of the front side glass. A lead-free glass having a temperature of ˜25 ° C. is used, and the glass on the front side and the glass on the back side are simultaneously fused and bonded under the same conditions.

  According to the method of manufacturing a magnetic head of the present invention, two different types of glass can be fused at the same time to the front side and the back side, so the number of steps is reduced, the glass is easy to flow, and the manufacture is facilitated. .

  According to the present invention, since the glass composition used for the magnetic head does not contain a lead component, the manufacturing environment of the magnetic head is improved, and there is an effect that the disposal process is not troubled. Further, according to the present invention, the glass portion appearing on the sliding surface of the magnetic head has a wear resistance equal to or higher than the glass portion of the sliding surface of the magnetic head using conventional lead glass, and has a glass transition. Since glass with a low point is used together on the back side of the magnetic head, the bonding strength between the magnetic core halves can be sufficiently secured.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a magnetic head according to an embodiment of the present invention. This magnetic head 31 is a so-called metal-in-gap (MIG) type magnetic head, and a high magnetic permeability metal magnetic thin film 33 is formed on the abutting surfaces of the ferrite core halves 32L and 32R. Both ferrite core halves 32L and 32R are joined using lead-free glass compositions 34 and 35 according to the embodiments described later so that a magnetic gap g is formed through a gap film (not shown). Configured. A coil 38 is wound around the ferrite core halves 32L and 32R via a winding groove 41. As shown in FIG. 1, in this example, the sliding surface side of the magnetic head 31 with respect to the winding groove 41 is defined as the front side 36, and the side opposite to the sliding surface with respect to the winding groove 41 is defined as the back side 37. . In the glass compositions 34 and 35, the glass composition formed on the front side 36 is referred to as a front side fused glass 34, and the glass formed on the back side 37 is referred to as a back side fused glass 35.
Here, as the front side fused glass 34, a lead-free glass composition having excellent wear resistance is used, and as the back side fused glass 35, a glass composition having a glass transition point lower than that of the front side is used. It is done. The glass composition at this time will be described with reference to Table 1 later.

  The shortest distance from the sliding surface to the winding groove 41 is the front depth Df, and the shortest distance from the bottom surface of the glass to the winding window is the back depth Db. At this time, the length Db of the back depth is always longer than the length Df of the front depth. In this example, it is optimal that the length Db of the back depth is 50 to 80 times the length Df of the front depth. If Db is shorter than 50 times Df, the mechanical strength as a magnetic head cannot be secured. Further, even if Db is larger than 80 times Df, the mechanical strength is saturated, and only material costs and man-hours are wasted.

  The magnetic tape slides only on the sliding surface of the magnetic head 31, and the back-side fused glass 35 is not slid. Accordingly, the front side fused glass 34 is responsible for wear resistance, and the back side fused glass 35 having a large volume is mainly responsible for improving the bonding strength of the gap.

  FIG. 2 shows a schematic configuration at the time of fusion of the ferrite core half block in the manufacturing process of the magnetic head 1 according to the present embodiment. First, the two ferrite core half blocks 43 and 43 in which the winding groove 41 and the glass groove 40 and the track width regulating groove 42 orthogonal to the winding groove 41 and the glass groove 40 are formed are connected to the winding groove 41 and the glass. Abutment is made so that the grooves 40 face each other. On the abutting surface side of these ferrite core half blocks 43, 43, a metal magnetic thin film formed by deposition is formed (not shown) including the inside of each groove. Then, rod-shaped glass compositions 44 and 45 are disposed in the winding groove 41 and the glass groove 40, and the glass is fused to perform bonding. At the time of glass fusing, as shown in FIG. 2, glass fusing is performed with the ferrite core half blocks 43 and 43 turned upside down so that the portion on the sliding surface side, the so-called front side 36, faces down. Therefore, the rod-shaped glass 44 serving as the front-side fused glass 34 is inserted into the winding groove 41, and the rod-shaped glass 45 serving as the back-side fused glass 35 is inserted into the glass groove 40. In this case, the distance L2 for flowing the glass to the back side 37 of the ferrite core half blocks 43, 43 is longer than the distance L1 for flowing the glass to the front side 36. For this reason, the temperature at which the glass can completely flow the distance L2 is the fusing temperature. In this example, the front-side fused glass 34 and the back-side fused glass 35 having different glass transition temperatures are simultaneously fused under the same conditions.

  As described above, the front side fused glass 34 and the back side fused glass 35 can be fused simultaneously under the same conditions, thereby reducing the number of steps. The fused ferrite core half blocks 43 and 43 are cut and polished.

  As described above, the high magnetic permeability metal magnetic thin film 33 is formed on the butt surfaces of the ferrite core halves 32L and 32R, and the magnetic gap g is formed between the metal magnetic thin films 33 via the gap film. The coil 38 is wound around a head chip formed by joining the ferrite core halves 32L and 32R with a glass composition. Then, the magnetic head 31 as shown in FIG. 1 is formed.

  Here, the distance L2 for flowing the glass 45 to the back side 37 of the ferrite core half blocks 43, 43 is 7 to 10 times the distance L1 for flowing the glass 44 to the front side 36 of the ferrite core half blocks 43, 43. Is preferred. If L2 is shorter than 7 times L1, mechanical strength cannot be secured in the manufacturing process of the magnetic head. Further, even if L2 is larger than 10 times L1, the mechanical strength is saturated and only material costs and man-hours are wasted.

  In the present embodiment, the dimensions of the finished product and the manufacturing process of the magnetic head are as follows. The distance L1 for flowing the glass 44 to the front side 36 of the head block in FIG. 2 is 75 μm, the distance L2 for flowing the glass 45 to the back side 37 of the head block is 650 μm, and the length Df of the front depth in FIG. Since the cylindrical polishing is performed in the processing, the length is 10 μm, and the length Db of the back depth is 650 μm like L2.

Next, Table 1 shows the composition of the fused glass used for the front side 36 and the back side 37 of the magnetic head 1 of this example and the composition of the fused glass used for the magnetic head according to the comparative example.

  In the glasses of samples 1 to 11 shown in the glass of Examples in Table 1, the glasses of samples 1 to 7 are used for the front side fused glass 34, and the glasses of samples 8 to 11 are the back side fused glass. 35 is used. The unit of numerical values displayed in Table 1 is mass%. In addition, what was put on "the glass of a comparative example" is each component which comprises the lead-free glass used for the magnetic head which remove | deviates this Embodiment, and lead-type glass.

Here, the glass used for the front side is Bi ₂ O ₃ : 60 to 68%, B ₂ O ₃ : 7 to 9%, ZnO: 4 to 6%, SiO ₂ : 13 in terms of mass% based on oxide. And lead-free glass composition comprising Na ₂ O: 2-4%, Sb ₂ O ₃ : 0-2%, Fe ₂ O ₃ : 2-7%, ZrO ₂ : 0-1% It is preferable (Sample 1 to Sample 5). In this case, by containing SiO ₂ at a certain ratio or more with respect to B ₂ O ₃ , the fusion temperature is 600 while having the wear resistance equivalent to or higher than that of leaded glass and ensuring chemical durability. Since it can be kept at or below ℃, the glass dent on the sliding surface is unlikely to occur.

In Samples 6 and 7, the content of B ₂ O ₃ is increased, but it has wear resistance by containing SiO ₂ and an Al-based component or Zr-based component, and The fusion temperature is suppressed to 600 ° C. or lower while ensuring chemical durability.

  Next, about each glass of the composition of Table 1, the thermal expansion coefficient (100-350 degreeC), glass transition temperature, and the wear area by a regular wear test were measured. The results are shown in Table 2.

Here, the specified wear test described above will be described.
As shown in FIG. 3, the specified wear test method uses an open reel long-distance friction measuring device, and the magnetic tape 2 on the side surface of the fixed drum 1 slides in a direction perpendicular to the tape running direction. The rod-shaped glass 3 is bonded with resin, and the magnetic tape 2 brought into contact with the glass with a constant tension is slid by a predetermined distance. The side surface of the glass 3 at that time is shown in FIG. 4, and a part of the glass is shaved with a tape, and the shaved portion is defined as a dense hatched area A. The scraped width 2Y was measured, and the scraped volume was calculated from the wire diameter 2R of the glass 3, the scraped width 2Y and the scraped length (depth). However, since the length (depth) of the cut glass 3 is the tape width, it is constant and there is no problem even if it is not included in the calculation for the comparison of the cut dimensions. And compared. Therefore, it can be said that the smaller the area, the better the wear resistance. Measure the outer diameter of each sample with glass drawn to an outer diameter of 0.5 ± 0.02 mm, and use epoxy resin to adhere the glass 3 to the sliding surface of the glass 3 with the magnetic tape 2. The resin was not attached. The environment (temperature and humidity) is set to 40 ° C and 30% in a thermostatic chamber, and Tape 2 uses a 1/4 inch wide vapor deposition tape (uses solid lubricant) for digital video. Every time the glass is changed, a new tape is used. Was used, and one way 140m was reciprocated 10 times. The tape speed at this time is 5 m / sec, and the drum 1 does not rotate. Moreover, the tension amount of the tape brought into contact with the glass is 17 g.

  The shaved area was determined as follows. As shown in FIG. 4 (cross section of the rod-shaped glass 3), the cut width is 2Y, the cut cross-sectional area is the dense shaded area A, and the sector area including the dense shaded area A and the coarse shaded area B From this, the area of the triangle (rough hatched area B) was subtracted to obtain a scraped area A.

Next, Table 3 shows combinations of lead-free glass on the front side and back side used in the magnetic head 31 according to the present embodiment, and the gap bonding strength and the winding of the winding groove 41 in the magnetic head 31 according to the combination. The determination result about the glass level difference of the space and the magnetic head sliding surface after running the tape for 50 hours is shown.
Moreover, the comparative example of Table 3 is based on the combination of the glass of the comparative example in Table 1 and Table 2.

In this example, as the front glass, a lead-free glass whose wear area by the specified wear test is equal to or less than that of the conventional lead-containing glass sample 14 (7.3 × 10 ⁻⁶ [mm ² ]), that is, in Table 1 Samples 1-7 were selected. Furthermore, as the glass on the back side, a glass that flows a distance of 7 to 10 times the distance that the front glass flows through the track width regulating groove of the head block under the same fusing condition as each front glass was selected.

  At this time, when comparing the glass transition temperature of the glass on the front side and the glass transition temperature of the glass on the back side, it was found that the latter, which is easy to flow, is lower, and the difference between 15 and 25 ° C. is suitable. If the difference in glass transition temperature is smaller than 15 ° C., the glass on the back side cannot completely fill the track width regulating groove, and the bonding strength of the gap cannot be sufficiently secured. This is an example shown in Comparative Example 1. If the difference in glass transition temperature is greater than 25 ° C., the glass on the back side will flow too much beyond the track width regulating groove, reaching the groove that becomes the winding hole in FIG. Therefore, the winding hole becomes small, and the winding work becomes difficult. This is an example shown in Comparative Example 2.

  Next, a 1/4 inch wide vapor-deposited tape for digital video (using a solid lubricant) was slid on each of the magnetic heads, and the step between the ferrite on the sliding surface and the glass was evaluated. The step between the ferrite and glass on the sliding surface when the tape is slid on the magnetic head shows the wear resistance of the head, not the wear resistance of the glass alone. The lower the step, the better the wear resistance. Here, the results of Example 1, Example 3, Comparative Example 1, and Comparative Example 3 are shown in FIG. In Example 1 and Example 3, the step difference between ferrite and glass after 75 hours is suppressed as compared with Comparative Example 1, and the same level as Comparative Example 3 which is a lead-based glass is maintained.

  5 shows the result of observing the interference fringes on the sliding surface after running the tape for 50 hours in the measurement of FIG. FIG. 6A shows a schematic diagram of the sliding surface of the magnetic head (however, one of the two heads with different azimuth directions is shown as a representative). Photo 1 is a photomicrograph of the sliding surface of the magnetic head, showing the magnetic metal thin film 33, ferrite core halves 32L and 32R, and front-side fused glass 34 of the head, respectively. In Photo 1, some ring-shaped fringes over the head are interference fringes, and the same height portions are connected by the same line. The deviation of the interference fringes represents a step. That is, the greater the deviation of the interference fringes, the greater the step between the ferrite core halves 32L, 32R and the glass 34 on the sliding surface, and the lower the wear resistance. The interference fringes before sliding are in a state of no deviation and no step (not shown). Photo 1 shows a state after 50 hours of tape running, that is, a state of interference fringes on a sliding surface slid for 50 hours. The left and right photographs are the sliding surfaces of a pair of magnetic heads with different azimuth orientations. In Comparative Example 1, the deviation of the interference fringes is large after running the tape for 50 hours, whereas in Examples 1 and 3, no step is seen even if the tape is run for 50 hours, and lead glass is used. It can be seen that it is possible to maintain the same level as that of a certain comparative example 3. As described above, it can be said that Example 1 and Example 3 are superior in wear resistance as a head as compared with Comparative Example 1.

The front side glass used in Comparative Example 1 and Comparative Example 2 has a wear area by a specified wear test larger than 7.3 × 10 ⁻⁶ [mm ² ]. End up. Therefore, this glass cannot be used for the sliding surface of the magnetic head.
It has been found that a magnetic head satisfying the conditions of claims 1 and 2 has characteristics equivalent to those of a conventional magnetic head using lead-based glass in wear resistance and gap bonding strength.
Furthermore, in the method of manufacturing a magnetic head satisfying the conditions of claims 3 and 4, a magnetic head equivalent to a conventional magnetic head using lead-based glass in wear resistance and gap junction strength can be produced, and a winding hole can be formed. It was found that the glass on the back side can be prevented from entering, and it is possible to produce a magnetic head with high yield and reliability.

As described above, according to the present invention, since the glass composition used for the magnetic head does not contain a lead component, it leads to an improvement in the manufacturing work environment of the magnetic head, and there is an effect that the disposal process is not troubled.
Conventionally, when lead-free glass is used for a metal-in-gap head that uses a magnetic core composed of a composite of an oxide magnetic material and a metal magnetic thin film, if it is fused at a low temperature that does not deteriorate the characteristics of the metal magnetic thin film, Although the surface wear resistance was significantly inferior, the sliding surface of the magnetic head according to the present invention has wear resistance equal to or higher than that of a magnetic head using leaded glass and has a glass transition point. Since low glass is used on the back side, the bonding strength between the magnetic core halves can be sufficiently secured.
It is possible to put it into practical use as a magnetic head that has a good electromagnetic conversion characteristic and a high bonding strength, in which glass dents hardly occur in any sliding part with respect to any magnetic tape.
In addition, since the method for manufacturing a magnetic head according to the present invention fuses two types of glass at the same time, the number of processes is small and the glass is easy to flow.

  While the present invention has been described with reference to one embodiment of the present invention, the magnetic head and the method for manufacturing the magnetic head according to the present invention are not limited to the above-described embodiment. For example, the MIG type magnetic head has been described as an example of the magnetic head according to the present invention.

1 is a schematic configuration diagram of a magnetic head according to an embodiment of the present invention. It is a schematic block diagram in the manufacture process of the magnetic head based on one embodiment of this invention. It is a schematic block diagram of the apparatus used for the regular abrasion test of this invention. It is explanatory drawing with which it uses for calculation of the area of the glass shaved by the regular abrasion test. It is the graph which showed the evaluation result of the level | step difference of a part of Example and a part of a comparative example, and showed the relationship between sliding time and a level | step difference. A, B Schematic diagram of sliding surface of magnetic head and after 50 hours sliding of magnetic head (one pair with different azimuth directions on left and right) using sliding glass of part of glass of Example and Comparative Example It is a microscope picture of the sliding surface.

Explanation of symbols

31 ... Magnetic head, 32R, 32L ... Ferrite core half, 33 ... Metal magnetic thin film, g ... Magnetic gap, 34 ... Front side fused glass, 35 ... Back side fused glass, 36 ... Front side, 37 ... Back side, 38 ... Coil, 40 ... Glass groove, 41 ... Winding groove, 42 ... Track width regulating groove, 43 ... Ferrite core half block, 44, 45 ... Glass

Claims (4)

In a magnetic head in which a pair of magnetic cores are fusion bonded with glass via a gap material,
As the glass that appears on the sliding surface on the front side, a lead-free glass having a wear area of 7.3 × 10 ⁻⁶ mm ² or less by a specified wear test is used,
A magnetic head, wherein the pair of magnetic cores are joined using lead-free glass having a glass transition point 15 to 25 ° C. lower than that of the front-side glass as the back-side glass. 2. The magnetic head according to claim 1, wherein the length of the back depth of the magnetic head is 50 to 80 times the length of the front depth. In a method of manufacturing a magnetic head in which a pair of magnetic cores are fusion bonded with glass through a gap material,
As the glass on the front side that appears on the sliding surface of the pair of magnetic core half blocks, lead-free glass having a wear area of 7.3 × 10 ⁻⁶ mm ² or less by a specified wear test is used.
And as the glass on the back side, lead-free glass having a glass transition point lower by 15 to 25 ° C. than the glass on the front side,
The method of manufacturing a magnetic head, wherein the front side glass and the back side glass are simultaneously fusion-bonded under the same conditions. The method for manufacturing a magnetic head according to claim 3, wherein a distance for flowing the glass on the back side of the half core block of the magnetic core is 7 to 10 times a distance for flowing the glass on the front side.