JPS6216444B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a laminated core chip that has excellent high frequency characteristics in the MHz range and is particularly suitable for use in manufacturing magnetic heads for VTRs. As is well known, the basic composition is Si: 5-12%,
Fe-Si-Al alloy consisting of Al: 3 to 8%, Fe and unavoidable impurities: the remainder (a well-known alloy usually called sendust, with a typical composition of Fe-9.6%Si-
Consists of 6.2% Al. The above percentages indicate weight percent. )teeth,
In addition to having favorable magnetic properties such as high saturation magnetic flux density and low noise during magnetic recording and reproduction,
Due to its excellent abrasion resistance, it is attracting attention as a material for core chips incorporated in the manufacture of magnetic heads for audio and VTR devices.In particular, it has been attracting attention recently as a material for magnetic heads that are compatible with alloy tapes with extremely high retention strength. It has been recognized as suitable as a material for core chips, and has been put into practical use to some extent in the audio field. However, when viewed as an alloy material, the Fe-Si-Al alloy mentioned above generally has poor castability and is brittle, so it is a material that is prone to chipping during cutting and polishing after casting. Currently, efforts are being made to improve workability by improving casting methods, purifying raw materials, adding special elements, etc., and pushing forward with practical application in the audio field as mentioned above. be. That is, the core chip used in an audio magnetic head is usually made of a laminate plate having a structure in which several Fe-Si-Al alloy layers and nonmagnetic insulating layers are alternately laminated, each having a thickness of 0.2 mm or less. The Fe-Si-Al alloy thin plate constituting this core chip is (a) formed by grinding and cutting a cast ingot;
(b) hot rolling of cast ingots that have been alloyed with special elements to improve workability; (c) molten metal is moved at high speed in the form of high-velocity jets and rapidly cooled during this movement to form amorphous ingots. (d) Fe-Si-Al alloy powder and Fe-Si-Al alloy powder as raw material powder. (e) A method in which a powder for forming a non-magnetic insulating layer is used, and both powders are filled in a press mold alternately in layers, and then sintered according to an ordinary powder metallurgy method; Therefore, it is manufactured by a method of alternately laminating several Fe-Si-Al alloy layers and nonmagnetic insulating layers with a thickness of several μm. On the other hand, when the above Fe-Si-Al alloy is used to manufacture the core chip of a magnetic head for a VTR,
In order to prevent the effective magnetic permeability from decreasing in the high frequency band, it is necessary to keep the thickness to 20 to 30 μm or less, but in the methods (a), (b), and (d) above, It is difficult to manufacture thin Fe-Si-Al alloy thin sheets, and some attempts have been made to manufacture Fe-Si-Al alloy thin sheets using methods (c) and (e) above. It's just that. However, (c) above
Even in the production of Fe-Si-Al alloy thin sheets by the molten metal cooling method, it is difficult to control the alloy composition and structure, so there are significant restrictions from the point of view of mass production. Even in the sputtering method, the deposition rate is at most 0.5 to 0.6μ.
m/hr, and it is not easy to control the alloy composition, so like method (c) above, it is a major obstacle in terms of production efficiency and mass production. The Fe-Si-Al alloy mentioned above is only used for special purposes such as core chips for heads, and is not used for general industrial or household purposes.
It is difficult to widely use the Fe-Si-Al alloy, which has excellent magnetic properties and wear resistance, especially in the high frequency range, for manufacturing magnetic head core chips for VTRs, and ferrite is still widely used in this field. The current situation is that From the above-mentioned viewpoint, the present inventors have developed an Fe-Si-Al based alloy that has excellent magnetic properties and wear resistance, especially in the high frequency range, for manufacturing general VTR magnetic heads for industrial or home use. As a result of conducting research to apply this method, we found that after depositing a metal thin film with a thickness of 1 μm or less on the surface of a ceramic substrate of a predetermined thickness, we further deposited Fe-Si-Al alloy powder on top of it by electrophoresis. Therefore, by depositing the alloy powder to a predetermined thickness and then heating it for a short time by scanning with a high-density energy beam, it is possible to easily control the alloy composition and deposit it on a ceramic substrate as a non-magnetic insulating layer in a state that can be mass-produced. Fe-Si-Al is extremely thin with a thickness of 20 to 30 μm or less, and has a high density and fine structure.
The laminated core chip cut out from the resulting laminated plate can be
They discovered that when used in the manufacture of magnetic heads for VTRs, it exhibits extremely excellent characteristics. This invention has been made based on the above findings, and the method of this invention will be described in further detail below. First, the ceramic substrate mentioned above has excellent heat resistance and thermal shock resistance, and has a low coefficient of thermal expansion.
0.2 to 0.3, relatively close to that of Fe-Si-Al alloys
It is preferable to use one with a thickness of mm. In this case, the softening point or melting point is appropriate as a measure of the heat resistance of the ceramic substrate, and it is better to use a ceramic substrate that has better heat resistance than Fe-Si-Al alloys, such as phosphorus. Preference is given to using telite, alumina, and beryllia. Table 1 shows the properties of these ceramics and Fe-Si-Al alloys having the above representative compositions. Table 1 also shows non-magnetic stainless steel and Ti, which are suitable for forming metal vapor deposited thin films in the subsequent process.

【table】

[Table] Additionally, ceramic substrates have no pores on their surfaces and can be sufficiently lapped with a polishing machine to achieve a surface roughness of 0.01.
It is preferable to use one finished to approximately 0.1μRmax. Next, Fe-Si was deposited on the above ceramic substrate.
- In order to enable deposition of Al-based alloys by electrophoresis, an electrically conductive evaporated thin film is formed on a ceramic substrate as a pre-process, but Fe- Si
- Non-magnetic metals that have a higher melting point than Al-based alloys and a thermal expansion coefficient close to that of Fe-Si-Al-based alloys (within ±15%), such as Ti shown in Table 1 and non-magnetic stainless steel. desirable. In addition, the thickness of the film is as thin as possible in order not to damage the magnetic properties of the Fe-Si-Al alloy.
It is preferable to make it less than μm. Subsequently, a photoetching method, which is used in the field of IC substrate manufacturing, is applied to the vapor-deposited thin film to form a core chip-shaped pattern that is electrically connected to each other. A porous layer of Fe-Si-Al alloy is deposited to a predetermined thickness on the vapor-deposited metal pattern formed on the surface of the ceramic substrate by the electrophoresis method. If the required thickness of the Al-based alloy layer is 20 μm, the thickness of the porous layer is 40 μm.
~50 μm is sufficient. Porous Fe-Si-Al formed in this way
A high-density energy beam is scanned along the pattern shape from above the Fe-Si-
When the Al-based alloy layer is exposed to a temperature near its melting point or higher for a short time, the Fe-Si-
Sintering (solid-phase or liquid-phase sintering) progresses in the Al-based alloy layer, and heat dissipates through the ceramic substrate, so the Fe-Si-Al-based alloy layer is rapidly cooled, resulting in rapid sintering. Highly densified Fe−Si−
This results in the formation of an Al-based alloy layer.
At this time, if the ceramic substrate is closely attached to a metal plate with high thermal conductivity and heat resistance, or even a water-cooled metal plate, heat dissipation will be further promoted. Deformation due to its own heat and other undesirable effects can be avoided. In addition, laser beams and electron beams can be used as high-density energy beams, but since the beam can be irradiated in the atmosphere or while blowing an inert gas stream, they have the advantage of not requiring a vacuum chamber. It is convenient to use a laser beam that has a In this way, a porous Fe film several tens of micrometers thick is attached to a ceramic substrate via a thin vapor-deposited film.
In order to heat, sinter, and densify only the Si-Al alloy layer, it is essential to apply a high-density energy beam, but in this case, it is necessary to avoid applying a considerable thermal shock to the underlying ceramic substrate. Since this cannot be avoided, it is necessary to avoid the occurrence of cracks due to thermal distortion by using a ceramic substrate with good heat resistance and thermal shock resistance as described above. In addition, as mentioned above, ceramic substrates and Fe-
If there is a large difference in the coefficient of thermal expansion of the Si-Al alloy, large residual strain may exist in the Fe-Si-Al alloy layer during the rapid cooling process after beam irradiation, or damage may occur due to thermal strain. As mentioned above, it is desirable to approximate the thermal expansion coefficients of both of them, since the characteristics will deteriorate when used as a core chip of a magnetic head.
The thermal expansion coefficient of the vapor-deposited thin film metal interposed between the ceramic substrate and the Fe-Si-Al alloy layer is
- By making it closer to that of the Si--Al alloy layer, the effect caused by the difference in thermal expansion coefficient can be alleviated. That is, the above-mentioned vapor-deposited thin film was originally formed by depositing Fe-Si-Al on a ceramic substrate.
It is formed to play the role of an electrode when adhering the related alloy powder by electrophoresis, but in addition to this role, as mentioned above, it is used to support the thermal expansion of the ceramic substrate and the Fe-Si-Al alloy layer. It has the function of alleviating the difference in coefficients, and is
It is desirable to use a metal with a small coefficient of thermal expansion within 20% of that of the Al-based alloy. For example, if beryllia or alumina is used in the production of ceramic substrates, a thin film of Ti or non-magnetic stainless steel is deposited. Good to apply as a forming metal. Finally, the surface of the dense Fe-Si-Al alloy layer in the laminate thus formed is polished to a predetermined surface roughness, e.g. 0.1, using a standard method.
After polishing to μmRmax, it is equipped with a built-in control computer, a beam positioner that can move the laser beam to any position on the workpiece with high precision and at a predetermined speed, and an automatic Nd:YAG laser. Laminated core chips are efficiently cut out using an automatic punching process using a laser trimming device or the like. Next, the method of the present invention will be specifically explained using examples. Example The magnetron sputtering method was applied to the surface of an alumina substrate with a thickness of 0.3 mm and a surface roughness of 0.1 μm, and by holding it in an Ar atmosphere with a pressure of 5 × 10 ^-3 torr for about 10 minutes. , Ti was deposited to a thickness of about 1 μm. Next, the Ti thin film on the alumina substrate was photo-etched to form an outer diameter of 5 mm x inner diameter of 3 mm.
After forming a ring shape with dimensions of mm and a pattern in the same shape as the core chip of a VTR magnetic head, methyl chloride: 50 c.c., iripropyl alcohol: 30 c.c., nitromethane: 20 c.c., zein :
Fe-9.2% with 0.3cc and average particle size 1μm
By applying the electrophoresis method to a mixed solution consisting of 5 g of Si-5.6% Al alloy powder under the conditions of energization and holding at a voltage of 100 V for 30 minutes, a thickness of approximately A porous Fe-Si-Al alloy thin film of 50 μm was formed. Then, after drying, a thin film of Fe-Si-Al alloy powder deposited on the alumina substrate via a Ti thin film was blown with gas: Ar, output: 1KW, mode: TEM ₁₁ + TEM ₀₀ , heat source area: 1 mm ² The material was irradiated with a CO ₂ gas laser beam at a beam movement speed of 80 cm/min and sintered in a semi-molten state. The resulting Fe-Si-Al alloy layer has an average thickness of
It had a high density of 28 μm, almost equal to the theoretical density, and was made of a sintered body with a fine structure and no defects. Subsequently, the Fe-Si-Al alloy sintered layer is polished to a thickness of 25 μm and a surface roughness of 0.1 μm or less, and then formed into a ring shape and a shape using the CO ₂ laser beam. A laminated ring and a laminated core chip are cut out by cutting the alumina substrate along the pattern of the core chip shape, and the laminated ring and the laminated core chip are subjected to strain relief annealing at a temperature of 500°C for 1 hour in an Ar gas atmosphere. Thus, a laminated ring and a laminated core chip (hereinafter referred to as the laminated ring of the present invention and the laminated core chip of the present invention) according to the method of the present invention were manufactured. For comparison purposes, an Fe-Si-Al alloy with the same composition of Fe-9.2%Si-5.6%Al was vacuum melted and then centrifugally cast, and the resulting ingot was sliced to a thickness of 100 μm. Then, a ring and a core chip (hereinafter referred to as conventional melting ring and conventional melting core chip) having the same shape as the laminated ring of the present invention and the laminated core chip of the present invention were cut out from this thin slice by electrical discharge machining. Furthermore, for comparison purposes, Fe-9.2%Si was deposited on the surface of 0.3 mm thick non-magnetic stainless steel having the same shape as the laminated ring of the present invention and the laminated core chip of the present invention, using the sputtering method.
A Fe-Si-Al alloy having a composition of -5.6% Al was deposited at a deposition rate of 0.3 μm/hr and a deposition time of 100 hours, and the resulting thickness was approximately 30 μm.
A comparative laminated ring and a comparative laminated core chip were manufactured by polishing the surface of the deposited Fe--Si--Al alloy layer to a thickness of 25 μm. Next, the effective magnetic permeability with respect to frequency was measured for the above three types of rings obtained as a result. The measurement results are shown in FIG. As shown in the figure, it is clear that the laminated ring of the present invention, together with the comparative laminated ring, exhibits superior effective magnetic permeability in the high frequency range of 1 MHz or higher compared to the conventional melting ring. On the other hand, in the comparative laminated ring, it took 100 hours to form an Fe-Si-Al alloy layer with a thickness of approximately 30 μm due to the sputtering method, whereas in the laminated ring of the present invention, the thickness was the same after sintering. Fe- with a thickness of about 50μm
The Si--Al alloy layer can be formed by electrophoresis in an extremely short time of 30 minutes, which makes efficient and economical production possible on an industrial scale. Further, the laminated core chip of the present invention and the comparative laminated core chip were incorporated into a magnetic head for a VTR, and the reproduction output of the head with respect to frequency was measured. The measurement results are shown in FIG. 2, and it is clear that the magnetic head incorporating the laminated core chip of the present invention has superior reproduction output compared to the magnetic head incorporating the comparative laminated core chip. Furthermore, after using the magnetic head incorporating the laminated core chip of the present invention for 10 hours, the amount of wear of the laminated core chip of the present invention is approximately 1/10 that of the conventional melted core chip.
It was only 1/2 of the comparable laminated core chip. As mentioned above, according to this invention, the thickness is 20~
Fe-Si-Al is extremely thin, less than 30μm, and has a dense and uniform microstructure with no microscopic holes or cavities, and has excellent magnetic properties and wear resistance.
A multilayer core chip with a sintered alloy layer can be efficiently produced in an extremely short manufacturing time, at low cost, and the resulting multilayer core chip can be used as a magnetic head for industrial or household VTRs. When incorporated and used, it provides industrially useful effects such as excellent performance over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a curve diagram showing the relationship of effective magnetic permeability to frequency for the laminated ring of the present invention, the conventional melting ring, and the comparative laminated ring. FIG. 2 is a curve diagram showing the relationship between head reproduction output and frequency for a magnetic head.

Claims (1)

[Claims] 1. 1 μm on the surface of a ceramic substrate with a predetermined thickness.
After depositing a metal thin film with the following thickness, we further deposit Fe-Si, which has excellent magnetic properties and wear resistance.
-Al-based alloy powder is deposited to a predetermined thickness by electrophoresis, and then the alloy powder is heated for a short time by scanning with a high-density energy beam to make it highly dense and form a sintered body with a fine structure. A method for producing a laminated core chip for a magnetic head, comprising the basic steps of cutting out a laminated core chip.