JPH0349127B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing an alloy magnetic head, and more particularly to a method for forming a narrow gap in a Sendust magnetic head compatible with a high coercive force tape for achieving high-density magnetic recording. Conventional technology In recent years, high coercive force tapes such as metal tapes are being used to improve magnetic recording density.
A magnetic head corresponding to this requirement requires a magnetic core material with a high saturation magnetic flux density that is unlikely to cause magnetic saturation near the magnetic core gap. Currently, a magnetic head with a high precision narrow gap using Fe-Al-Si alloy as the core material for such a high-performance magnetic head is considered to be one of the most suitable, and its widespread use is expected in the field of magnetic recording. coveted. However, Fe-Al- used as core material
Due to the nature of Si-based alloys, it is extremely difficult to form narrow gaps with high precision and high mechanical strength, and this has prevented the spread of the above-mentioned magnetic heads. In the case of ferrite, it bonds extremely strongly to the glass, so the glass serves as both the spacer material for the front gear and the bonding material for the core. but
Fe-Al-Si alloys have poor wettability with glass;
In most cases, joining using this method is difficult. Therefore, in order to separate the role of a spacer and the role of joining required for the gap part, a thin film of spacer material is formed on the front gap forming surface to control the gap length of the front gap, and the spacer material is wound to improve the mechanical strength of the gap part. Methods such as joining the inner surfaces of wire windows are being used (for example, Japanese Patent Publication No. 56-130811, Japanese Patent Publication No. 57-
Publication No. 60525). A thin quartz film (SiO ₂ ) is usually used as a spacer for the front gap of a Fe-Al-Si alloy head.
is used. A thin quartz film is formed on the front gap forming surface of the Fe-Al-Si alloy core half using a vapor deposition method, and the gap is joined by butting it against the front gap forming surface of the mating Fe-Al-Si alloy core half. Ru. In this case, _SiO2 is Fe−Al−
Because it has poor wettability with Si-based alloys, sufficient bonding strength cannot be obtained. Bonding for strength is
This is done using braze or resin in selected locations such as winding windows and back gaps that will not adversely affect head performance. Furthermore, since the magnetic head must undergo processes such as cutting and mechanical polishing after gap bonding, it is necessary that the bonding strength of the back gap surface, which is responsible for the bonding strength of the core, be extremely high. For this reason, normally a groove is formed on the backgap forming surface of the sendust, and a silver solder rod is inserted into this groove for bonding. (For example, Special Publication 58-
17530 Publication) Problems to be Solved by the Invention If quartz (SiO ₂ ) is formed on the front gear surface and a gap is formed by butting these together (if they are not joined), it will be difficult to run the tape. As a result, magnetic powder, dust, etc. that fall off get into the spaces between the gaps, causing a decrease in the accuracy of the gaps. Furthermore, the silver brazing material used on the back gap surface is generally a low melting point Ag-Cu-Cd-Zn brazing rod or foil to increase the bonding strength with the Fe-Al-Si alloy. However, this brazing filler metal has a large coefficient of thermal expansion (17 to 18 x 10 ^-6 /℃) and also has a large interdiffusion with the Fe-Al-Si alloy during gap formation, so when the silver filler metal solidifies after melting,
Cracks occur in the Fe-Al-Si alloy, and as a result of this, it is difficult to control the gap length and obtain parallelism. Furthermore, when wax foil is used, its thickness is 2 to 3 μm and the gap length is 0.3 to 0.5 μm.
m), so the pair of cores are strongly held down with a jig during the welding process by heat treatment.
It is necessary to push out the excess filler metal. However, this operation causes the pair of cores to shift when the filler metal melts, resulting in a decrease in the accuracy of the track width of the front gear. Means to Solve the Problems The purpose of the present invention is to overcome these drawbacks and manufacture a Fe-Al-Si magnetic head that has a narrow gap with high precision and has excellent mechanical strength. , we have investigated the gap formation method.
For example, the front gap forming surface of the Fe-Al-Si alloy core half is made of a non-magnetic ceramic material with a coefficient of thermal expansion similar to that of the Fe-Al-Si alloy.
A ZrO ₂ thin film is formed on the back gap forming surface.
After forming the Ag-Cu-In alloy thin film, Ag-Cu
-We have devised a method of gap joining by pressurizing and heating the pair of core halves with their gap-forming surfaces butted against each other at a temperature higher than the melting temperature of the In-based alloy (Japanese Patent Application No. 171906/1982). However, Fe−Al−Si
Even in the case of alloys, it is desirable to use SiO ₂ as the spacer for the front gap because it is easy to control the thickness of the film and it is easy to obtain a uniform and smooth film. We first formed a SiO ₂ thin film using the sputtering method on Sendust, which is a representative Fe-Al-Si magnetic alloy, and then deposited Na ₂ O-PbO- on top of it.
The present inventors have discovered that when a glass thin film of SiO ₂ composition is formed and heat-treated in a vacuum atmosphere, the sendust SiO ₂ interface is firmly bonded, leading to the present invention. In order to solve the above problems, the present invention provides a pair of
After forming an SiO ₂ thin film with a uniform thickness on the front gap forming surface of the Fe-Al-Si based alloy core half and further forming a lead-containing glass thin film on top of that, a thin SiO 2 film was formed on the back gap forming surface as well. A thin Ag-Cu-In alloy thin film with a melting point and thermal expansion coefficient relatively similar to that of Fe-Al-Si alloys is formed by controlling the thickness with high precision, and a pair of Fe-Al-Si alloy core halves are formed. To provide a method for manufacturing a magnetic head with high precision and high mechanical strength, by performing heat treatment in a non-oxidizing atmosphere while abutting the magnetic heads to form a gap joint. Effect The present invention has a pair of Fe-Al
-By joining the Si-based alloy core halves,
At the interface between SiO ₂ and lead-containing glass, a very thin compound is formed by a chemical reaction, and a gap with considerably high mechanical strength can be obtained. Furthermore, since the reaction layer occurs only on the very surface, this gap length can be determined by the thickness of the SiO ₂ thin film and the lead-containing glass thin film. Next, Ag− on the back gap surface.
Since the film thickness of the Cu-In alloy can be controlled to the combined thickness of the SiO ₂ and lead-containing glass that form the front gap, there is no leakage of molten silver solder during heat treatment, unlike when using foil. Therefore, the pair of alloy cores will not shift. Also, Ag−Cu−
Im-based alloys cause very slight interdiffusion at the joints with Fe-Al-Si-based alloys, making it possible to form strong, crack-free backgap joints. Examples Examples will be shown below. Example 1 A Fe--Al--Si alloy head having a gap as shown in FIG. 1 was manufactured and examined using the method shown below. First, the width is 3 mm, the height is 2 mm, and the length is as shown in Figure 2 a.
A pair of head core halves 1 and 2 are prepared on a 20 mm rod-shaped Fe-Al-Si alloy with grooves for winding 0.35 mm in width made using a diamond grindstone, and a front gap forming surface 7 and a back gap forming surface are prepared. Surface 8 is mirror polished (maximum surface roughness R max x 0.01μ
m) did. Next, as shown in Figure 2b, quartz (SiO ₂ ) is applied to each front gap forming surface using a sputtering method.
A thin film 3 containing lead was formed thereon, and a lead-containing glass thin film 4 was further formed thereon by the same sputtering method. (In this case, a mask was applied to the backgap forming surface to prevent SiO ₂ and lead-containing glass from entering.)
Here, the quartz thin film mentioned above has a uniform thickness of 0.10 μm.
It was hot. On the other hand, the lead-containing glass thin film mentioned above has a uniform thickness of 0.05 μm, and its composition is as follows:
It is a glass thin film consisting of 20% by weight of SiO ₂ , 75% by weight of Pbo and 5% by weight of Na ₂ O. Next, an Ag--Cu--In alloy thin film 5 was formed on each back gap formation surface using the same sputtering method. (In this case, mask the front gap forming surface to prevent Ag-Cu-In alloy from adhering.) Here, the Ag-Cu-In thin film mentioned above has a uniform thickness.
0.15μm, its composition is Ag55wt%, Cu wt%,
In is 15% by weight. The front gap side (SiO ₂ -lead-containing glass layer) and back gap side (Ag-Cu
-In layers) were brought into contact with each other and treated in a vacuum atmosphere (1×10 ⁻⁴ /Torr) at a temperature of 900° C. for 1 hour to form a gap bond. The gap-jointed core half block shown in Fig. 3 obtained in this way was processed into a 150 μm flake by cutting and mechanical polishing.
An alloy head chip was obtained. The front gap and back gap of the obtained Fe-Al-Si alloy head chip were polished, and the gap length was measured using an optical microscope.
As a result, it was observed that the gap length of the front gap and the back gap of the back gap were both 0.30 μm, and the gap ends were parallel. Moreover, there were no cracks or chips on the joint surfaces of either the front gear or the back gear. Furthermore, in order to examine the mechanical strength of the gap formed, Fe-Al-
A tensile test of the Si-based alloy material under a stress of 10Kg/mm ^-2 revealed that it did not peel at the gap joint surface and had excellent mechanical strength. Next, when the track width of the front head was mechanically processed to 25 μm, and the magnetic tape was attached to this magnetic head (coercive force Hc;
1400 Oersted saturation magnetic flux density Br; 3000 Gauss) was run at a relative speed of 3.455 m/sec, no "chips" were observed in the gap section. Also, when the coil is wound 25 turns around the winding window of this head, the reproduction front output voltage of the head at 5MHz is:
It was 240μV (heat to peak). The results are shown in sample number 1 in Table 1. Below, the results of various tests on samples with different compositions of lead-containing glass used in the front gap section are shown in sample numbers 2 to 4 in Table 1 using the same method. In this example, analysis using an X-ray microanalyzer confirmed that the composition of the Fe-Al-Si alloy, which affects magnetic properties, did not change at all before and after the heat treatment. . As a result, the saturation magnetic flux density B _S of Fe-Al-Si alloy is
is 8650 Gauss, coercive force H _C is 0.03 Oersted,
The AC initial magnetic permeability μ was 61 (when the thickness was 200 μm), and no change in magnetic properties was observed due to heat treatment. In addition, the Si ions, which are the composition of the quartz film, are
It was also confirmed that it was not diffused into the Fe-Al-Si alloy to a depth of 0.01 μm or more. Also, for comparison,
A head chip with a gap was fabricated using a conventional forming method. In other words, a quartz film is formed on the front gap, and a quartz film is formed on the back gap and winding window.
The head core halves were welded using an Ag-Cu-Zn-Cd system silver solder rod, and the same Fe-
An Al-Si alloy head chip was fabricated. The gap portion of this head chip was also tested in the same manner as in the example. As a result, in a tensile test using an external force of 10 kg/mm ^-2 , it did not peel off, but the parallelism of the gap edges was significantly poor. The gap length of the front gap was 0.50 μm, and the gap length of the back gap was 0.35 μm. Next, when the front part of the head was machined and the magnetic tape was run in the same way as in the example, chipping occurred in the gap portion. Furthermore, when the coil was wound 25 turns around the winding window of this head, the reproduced output voltage of the head at 5MHz was 60μV _pp . This result is also shown in sample number 5 in Table 1.

[Table] *Effects of Comparative Example Invention As is clear from the above explanation and Table 1, the present invention provides an Fe-Al-Si alloy magnetic head with
A quartz thin film is formed with a highly accurate thickness on the front gap forming surface (magnetic tape running surface) of a pair of Fe-Al-Si alloy core halves, and a lead-containing glass thin film is further formed with a uniform thickness on top of the quartz thin film. After forming an Ag-Cu-In based thin film on the back gap forming surface, the front gap is bonded by processing in a vacuum atmosphere above the softening point of glass and above the temperature at which silver solder melts.The front gap contains a quartz thin film and lead. A gap with high mechanical strength can be obtained by a chemical reaction between the glass thin film and its joint surfaces. In addition, the Ag-Cu-In thin film of the back gap and the Fe-Al-Si alloy bond very strongly, making it easy to form a narrow gap with high precision. -It has become possible to realize a Si-based alloy magnetic head. In addition, in the examples, the heat treatment atmosphere for Fe-Al-Si alloy welding was performed in a vacuum, but the atmosphere is not limited to this.
It has been confirmed that all methods (such as Ar or H ₂ atmosphere) are effective.

[Brief explanation of drawings]

Figure 1 shows Fe-Al- in one embodiment of the present invention.
Cross-sectional views of the Si-based alloy magnetic head, Figures 2a and b are
Figure 3 shows a pair of Fe-Al-Si alloy core halves used to form a gap in an Fe-Al-Si alloy magnetic head. FIG. 4 is a cross-sectional view of a conventional magnetic head chip, showing the gap-jointed core half blocks produced. 1, 2...Fe-Al-Si alloy core half, 3...
...Quartz layer, 4...Lead-containing glass layer, 5...Ag-
Cu-In layer, 6... Winding window, 7... Front gap part, 8... Back gap part, 9... Non-magnetic thin film part bonded with quartz and lead-containing glass, 10...
...Welded part using Ag-Cu-In alloy thin film.

Claims (1)

[Claims] 1. In a magnetic head made of Fe-Al-Si alloy magnetic core material, a two-layer thin film of quartz (SiO ₂ ) and lead-containing glass is formed as a nonmagnetic layer on the front gap forming surfaces of a pair of alloy core halves to form a back gap. After forming an Ag-Cu-In alloy thin film on the surfaces, the softening temperature of the lead-containing glass and the Ag
- Manufacture of an alloy magnetic head characterized by forming a magnetic gap by heat-treating in a non-oxidizing atmosphere at a temperature higher than the melting temperature of the Cu-In alloy and joining the pair of alloy core halves. Method.