JPS6254807A - Magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To prevent generation of a micro crack by using a material whose thermal expansion coefficient is between a value nearly equal to a smaller thermal expansion coefficient of a metallic magnetic thin plate or of a ferrite plate and a value smaller than the said value by 15% for a glass group adhesives. CONSTITUTION:The thermal expansion coefficient of the glass group adhesives 4 is selected to a value nearly between either smaller thermal expansion coefficient of the metallic magnetic thin plates 3a, 3b and of the ferrite plates 2a-2d (e.g., 130X10<-7>/ deg.C) and a value smaller than the said value by 15% (110X10<-7>/ deg.C). Thus, the magnetic head 1 with excellent magnetic recording reproducing output, without micro crack and with large mechanical strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head and a method for manufacturing the same, and particularly relates to a magnetic head having a composite structure in which a ferrite material and a metal magnetic alloy material are laminated and bonded using a glass adhesive. .

Conventional technology In general, magnetic heads compatible with magnetic tapes (such as metal tapes) having high coercive force require a high saturation magnetic flux density during recording, and a high saturation magnetic flux density is required during playback, especially in the high frequency range, in order to obtain sufficient playback sensitivity. It is required to have high magnetic permeability. Sendust (registered trademark) is a magnetic head material that can achieve high saturation magnetic flux pollution.
, metal magnetic alloy materials such as amorphous alloys, and magnetic ferrite materials are known as magnetic head materials having high magnetic permeability. However, magnetic heads made only of metal magnetic alloy materials have good characteristics during recording, but during reproduction, the magnetic permeability decreases due to eddy currents due to the small electrical resistance of the metal magnetic alloy material, especially at the operating frequency. As the culm permeability increases, the decrease in culm permeability is significant and the reproduction characteristics become poor.

Similarly, a magnetic head made only of magnetic ferrite material has good characteristics during reproduction, but poor characteristics during recording. Therefore, in order to improve the characteristics during both recording and reproduction, various magnetic heads having a composite structure of a metal magnetic alloy material and a magnetic ferrite material have been devised. Conventionally, this type of magnetic head with a composite structure has a structure in which 1yln-Zn ferrite material is bonded to both sides of a thin plate made of a metal magnetic alloy material with a high melting point glass material, and the gap of the magnetic head is A low melting point glass material was disposed in the track width regulating groove on the tape sliding surface.

Problems to be Solved by the Invention In the magnetic head having the above configuration, the high melting point glass that joins the metal magnetic alloy material and the ferrite material has a coefficient of thermal expansion in a range between the thermal expansion coefficients of the metal magnetic alloy material and the ferrite material. things were selected.

As is well known, in order to bond a metal magnetic alloy material and a ferrite material using high melting point glass, it is necessary to heat the high melting point glass to a temperature at which it melts, and then to avoid cooling.

However, if the thermal expansion coefficient of the high melting point glass is selected to be in the range between the thermal expansion coefficients of the metal magnetic alloy material and the ferrite material, the temperature of the high melting point glass, the metal magnetic alloy material, and the ferrite material will increase during heating and cooling of the high melting point glass. The three components exert stress on each other due to thermal expansion and contraction. Therefore, in conventional magnetic heads, due to the generation of the above-mentioned stress, so-called microcracks occur in the ferrite material after the metal magnetic alloy material and the ferrite material are joined and integrated, and the magnetic properties of the metal magnetic alloy material deteriorate. There have been problems in that the mechanical strength of the magnetic head is weakened and the magnetic recording and reproducing characteristics are deteriorated.

Therefore, an object of the present invention is to provide a magnetic head that solves the above problems by appropriately selecting the coefficient of thermal expansion of the glass adhesive.

Means for Solving the Problems In order to solve the above problems, the present invention provides a magnetic head having a composite structure in which a metal magnetic alloy material and a ferrite material are bonded together using a glass adhesive. A material whose thermal expansion coefficient is within the range of a value approximately equal to the smaller of the thermal expansion coefficient of the metal magnetic alloy material or the thermal expansion coefficient of the ferrite material, and a value 15% smaller than this value. was selected. Further, in the method for manufacturing a magnetic head, the metal magnetic alloy material and the ferrite material have a thermal expansion coefficient substantially equal to the smaller of the thermal expansion coefficient of the metal magnetic alloy material and the thermal expansion coefficient of the ferrite material; When bonding materials with a glass adhesive selected within the range of 15% smaller than this value, when the glass adhesive is melted and then cooled, the glass adhesive is The sample was maintained at a temperature corresponding to the annealing point of the agent for a predetermined period of time.

Embodiment FIG. 1 shows an embodiment of the magnetic head according to the present invention. The magnetic head 1 shown in the figure generally includes ferrite plates 2a to 2d,
Metal magnetic alloy thin plate (hereinafter referred to as metal magnetic thin plate) 3a,
3b, a glass-based adhesive 4.5 (shown in matte finish in the figure), etc., is a composite structure magnetic head. The ferrite plates 28 to 2d are made of Mn-Zn ferrite having high magnetic permeability, and have a structure in which a metal magnetic thin plate 3a is held between the ferrite plates 2a and 2b, and a metal magnetic thin plate 3b is held between the ferrite plates 20.2d. . The metal magnetic thin plates 3a and 3b are Fe-Si-Ae having high saturation magnetic flux density.
It is made of a metal alloy (Sendust, Sendust is a registered trademark), and its thickness is selected to be approximately equal to the predetermined track width. The ferrite plates 2a, 2b and the metal magnetic thin plate 3a constitute a magnetic head half 1a, and the ferrite plates 2c, 2d and the metal magnetic thin plate 3b constitute a magnetic head half 1b.

A glass adhesive 4 made of high melting point glass is applied to the metal magnetic thin plate 3a on the gap surface of each magnetic head half 1a, 1b.
, 3b are placed between them.

This gap surface is mirror-polished and then sputtered with a gap material (for example, S!02), and each magnetic head half 1a, lb is made of a metal magnetic thin plate 3a.

3b are positioned so that they are butted against each other, and then bonded using a glass adhesive 5 made of low melting point glass. Therefore, in the vicinity of the gap 7 of the sliding contact surface 6 of the magnetic tape, the metal magnetic thin plates 3a and 3b are arranged in the glass adhesive 4, and the magnetic tape has the metal magnetic thin plates 3a and 3b.
, 3b, magnetic recording is performed with a narrow track width corresponding to the thickness dimension of 3b, and high-density recording can be performed. In addition, 8~
10 is a coil winding groove.

Here, ferrite plates 2a to 2d, metal magnetic thin plates 3a, 3
b. The following description will focus on the coefficients of thermal expansion of the glass adhesive 4. As is well known, in the case of the magnetic head 1 having a composite structure, the magnetic head 1 includes ferrite plates 2a to 2d and a metal magnetic thin plate 3a.

3b, if there is a large difference in the expansion coefficients of the glass adhesive 4, the ferrite plates 2a to 2d may peel off during and after manufacturing the magnetic head 1, or the mechanical strength and magnetic properties may deteriorate. Are known. Therefore, as mentioned above, the coefficient of thermal expansion of the glass adhesive 4 is the same as that of the ferrite plate 28.
It was common to select a value between the coefficient of thermal expansion of ~2d and the coefficient of thermal expansion of the metal magnetic thin plates 3a and 3b, but even in this case, microcracks and deterioration of magnetic properties occurred. In view of this, the present inventor prepared glass adhesives 4 having various coefficients of thermal expansion, used them to fabricate a magnetic head 1, and investigated its magnetic recording and reproducing characteristics and the occurrence of microcracks. The experimental results are shown in the table below. The thermal expansion coefficient of the ferrite plates 2a to 2d is 134X10'/'
C, and the coefficient of thermal expansion of the metal magnetic thin plates 3a and 3b is 130.
×10'/'C.

From this experimental result, the thermal expansion coefficient of the glass adhesive 4 is the same as that of the ferrite plates 2a to 2d and the metal magnetic thin plate 3a.
, 3b (in this experiment, the thermal expansion coefficients of the metal magnetic thin plates 3a and 3b), the regeneration ratio no.j becomes large.

Also, focusing on the occurrence of micro-cranks, when the thermal expansion coefficient of the glass adhesive 4 is 100x 10-7/'C or less, and when it is larger than the thermal expansion coefficient of the gold alloy plates 3a and 3b, the ferrite plates 2a to 2d, and furthermore, the coefficient of thermal expansion of the glass adhesive 4 is higher than that of the ferrite plate 2.
Those that are significantly different from the thermal expansion coefficients of a to 2d (approximately -
20% or more), the ferrite plates 2a to 2d were separated from the metal magnetic thin plates 3a and 3b and could not be joined. From the above experimental results, the thermal expansion coefficient of the glass adhesive 4 is approximately equal to the smaller of the thermal expansion coefficients of the metal magnetic thin plates 3a and 3b and the thermal expansion coefficients of the ferrite plates 2a to 2d (in this example, 130x10'/'C) and a value 15% smaller than this value (110X 10-7/'C)
It is considered that by selecting a value within the range of , it is possible to obtain a magnetic head 1 with good magnetic recording/reproducing output, no microcracks, and high mechanical strength. Here, FIG. 2 shows the reproduction output characteristics (indicated by the arrow in the figure) of a magnetic head in which the thermal expansion coefficient of the glass adhesive 4 is 124X10-7X℃, and the thermal expansion coefficient is 134X1.
The reproduction output characteristic (indicated by arrow B in the figure) of the magnetic head with 0'/'C is shown. From the figure, the magnetic head in which the coefficient of thermal expansion of the glass adhesive 4 is selected within the above-mentioned predetermined range is approximately 3c in all frequency ranges, compared to the magnetic head in which the coefficient of thermal expansion of the glass-based adhesive 4 is selected within the above-mentioned predetermined range.
It can be seen that the B reproduction output voltage has improved. Therefore, by configuring the magnetic head 1 as described above, the magnetic characteristics can be improved.

The method for manufacturing the magnetic head according to the present invention is illustrated in FIGS. 3 to 11.
This will be explained below using figures. Note that components corresponding to those shown in FIG. 1 will be described using the same reference numerals. Third
In the figure, 2 is a ferrite plate made of 1yln-Zn ferrite having high magnetic permeability, and both sides thereof are mirror polished. First, a plurality of these ferrite plates 2 (nine in the figure) are arranged, and then, as shown in FIG. 4, grooves 11 which will later become track width regulating grooves are formed. At this time, the grooves 11 are formed at an angle θ corresponding to the azimuth angle with respect to the edges of the arranged ferrite plates 2.

Next, on both sides of each ferrite plate 2 in which the grooves 11 were formed, a lead-based glass thin layer (which functions as an adhesive) with a thermal expansion coefficient of 124×10′/”C was sputtered to a thickness of approximately 1 μm. It is formed by a well-known method such as spin coating.A plurality (eight in the figure) of metal magnetic thin plates 3 made of Fe-Ae-SR sendust having a high saturation magnetic flux density are arranged between each of the ferrite plates 2. Therefore, each metal magnetic thin plate 3 is sandwiched between each ferrite plate 2 as shown in FIG. In addition, the metal magnetic thin plate 3 is formed with alumina oxide (A!!, z 03 )', Dioxide'
yIron (S iOz ), titanium Mide (TiO2)
A thin oxide film of , forsterite, or the like is formed, and the above-mentioned lead-based glass thin layer is formed on this oxide thin film by a known method.

After arranging the ferrite plate 2 and the metal magnetic thin plate 3 as shown in FIG. At the same time, the glass adhesive is heated and cooled according to the temperature profile shown in FIG. 6 to bond each ferrite plate 2 and the metal magnetic thin plate 3. In FIG. 6, first, in the heating step, the predetermined working temperature Tw of the glass adhesive is changed from room temperature to the temperature Tw (temperature 9 at which the glass adhesive melts and joins the ferrite plate 2 and the metal magnetic thin plate 3, 760°C in this example). Heat in a vacuum atmosphere until the temperature reaches The reason for heating in a vacuum atmosphere is that the glass adhesive disposed in the groove 11 starts to melt between its softening temperature (500°C) and the working temperature Tw (760°C), but at this time By melting the glass-based adhesive inside the chamber, the bubbles contained in the glass-based adhesive filled in the glass float to the surface of the glass-based adhesive. This is to dissipate the bubbles by flushing them away in an inert gas flow atmosphere (for example, at a flow rate of 1 minute per minute).

Next, after the glass adhesive reaches the working temperature Tw, the above-mentioned inert gas atmosphere is created and this working temperature TW is maintained for 15 to 60 minutes. During this time, the ferrite plate 2 and the metal magnetic thin plate 3 are laminated and bonded, and the groove 11 is evenly filled with the glass adhesive.

In the subsequent cooling process, cooling is performed in the range of 2°C to 50°C per minute until the temperature corresponds to the annealing point of the glass adhesive and the lead-based glass coated on the metal magnetic thin plate 3 (hereinafter referred to as annealing temperature TC). Cool at speed.

By selecting the cooling rate within the above range, the influence of stress strain on the ferrite plate 2 and metal magnetic thin plate 3 due to the glass adhesive and lead glass in a fluid state can be reduced. Next, the annealing temperature T is the boundary temperature at which the glass adhesive and lead-based glass change from a fluid state to a solid state.
This state was maintained for a predetermined time (approximately 60 minutes) at c (370°C in this example. Figure 7 shows the temperature characteristics of thermal expansion of the ferrite plate 2, metal magnetic thin plate 3, and glass adhesive.) do. As a result, when changing from a fluid state to a solid state,
It can remove distortion that occurs in the glass adhesive and lead-based glass, and it can also eliminate cracks and cracks that occur in the filled glass adhesive and the lead glass that joins the ferrite plate 2 and the metal magnetic thin plate 3. Therefore, the mechanical strength of the magnetic head 1 can be increased. In addition, by removing the strain in the glass adhesive and lead glass, stress due to strain is no longer applied to the ferrite plate 2 and metal magnetic thin plate 3, and the magnetic properties of the ferrite plate 2 and metal thin plate 3 are improved. Deterioration can also be prevented. After maintaining the annealing temperature TC at a predetermined time, natural cooling is performed until the temperature reaches room temperature. Ferrite plate 2 and metal magnetic thin plate 3 joined according to the above series of temperature profiles
forms a substantially cubic block 12 shown in FIG.

In addition, in the figure, the glass adhesive 14 is shown in a satin finish. In addition, in the above bonding process, each ferrite plate 2 and the metal magnetic thin plate 3 are bonded under pressure (indicated by arrow P in FIG. 5), so the lead glass coated on the metal magnetic thin plate 3 is the same as before bonding. In comparison, the thickness dimension is set to a slightly smaller value.

The block 12 is cut at the position shown by the broken line in FIG. 8, and each of the cut blocks 12a and 12b is further cut at the position shown by the broken line in FIG. 9 to form the rod-shaped magnetic head block 13 shown in FIG. Form.

Next, this magnetic head block 13 is attached with glass adhesive 4.
The magnetic head block halves 13a and 13b are formed by cutting in the longitudinal direction at the disposed positions (FIG. 10 shows the already cut state). This magnetic head block half-break 1
3a, 13t) are formed with coil winding grooves 8, 9, 10, respectively, and glass bonding grooves 14a, 14b.

Furthermore, after mirror-polishing the gap abutting surfaces 15a and 15b, a gap material (for example, a quartz glass film, 5iOz) is sputtered onto the gap forming portions of the abutting surfaces 15a and 15b, each having a thickness of 1/2 of the predetermined gap width. Forms a film. Next, the pair of magnetic head block halves 13a and 13b are positioned so that the metal magnetic thin plates 3 are butted against each other, and then the glass bonding grooves 14a and 14 are
B is filled with low melting point glass and the magnetic head block is half closed 13
A and 13b are joined to form a magnetic head block 16 in which a gap 7 shown in FIG. 11 is formed. At this time, the low melting point glass has a softening temperature (350°C) lower than the softening temperature of the glass adhesive 4 (500°C in this example).
C.), and in actual joining, the pair of magnetic head block halves 13a, 13b are joined by heating to a temperature approximately 100.degree. C. higher than the softening temperature of the low melting point glass. Therefore, a pair of magnetic head block halves 1
In the joining process of 3a and 13b, the glass adhesive 14
will not melt, and no strain or stress due to this strain will occur in the vicinity of the gap 7. 11th
The magnetic head block 16 shown in the figure is core-sliced to a predetermined thickness by sandwiching a gold Ti1m thin plate 3, and R polishing is performed on the sliding contact surface 6 of the magnetic tape, and the magnetic recording and reproducing characteristics shown in FIG. A magnetic head 1 having excellent properties and high mechanical strength is formed.

Effects of the Invention As described above, according to the magnetic head and manufacturing method of the present invention, the glass-based adhesive has a coefficient of thermal expansion that is equal to or greater than the coefficient of thermal expansion of the metal thin plate and the ferrite plate. By selecting a material within the range of a value approximately equal to the smaller value and a value 15% smaller than this value, generation of microcracks can be prevented and the mechanical strength of the magnetic head can be increased. At the same time, the stress exerted by the glass adhesive on the ferrite plate and metal magnetic thin plate is reduced, and the magnetic properties of the ferrite plate and metal magnetic thin plate are not deteriorated, so the magnetic recording and reproducing characteristics are improved in all frequency ranges. In addition, when bonding a metal magnetic thin plate and a ferrite plate with the above-mentioned glass adhesive in the manufacturing process of a magnetic head, when the glass adhesive is melted and then slowly cooled, the glass adhesive is melted and then slowly cooled. By holding the glass adhesive at the temperature corresponding to the point for a specified period of time, it is possible to prevent the distortion that occurs in the glass adhesive when it changes from a fluid state to a solid state, thereby preventing cracks or cracks in the joint. This also increases the mechanical strength of the magnetic head, and in addition, by removing the strain on the glass adhesive, stress caused by strain on the ferrite plate and metal magnetic thin plate is eliminated. It has the advantage that it is possible to prevent the deterioration of the magnetic properties of the ferrite plate and the metal magnetic thin plate by eliminating the application of the current, and therefore it is possible to realize a highly reliable magnetic head.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the magnetic head according to the present invention;
Figure 2 is a diagram for explaining the reproduction output characteristics of the magnetic head shown in Figure 1, Figures 3 to 5, and Figures 8 to 11.
The figure is a perspective view for explaining the manufacturing method of the magnetic head according to the present invention according to the manufacturing procedure, FIG. 6 is a diagram showing the temperature profile during heating and cooling of the glass adhesive, and FIG. 7 is a diagram showing the metal magnetic head. FIG. 3 is a diagram showing the temperature characteristics of thermal expansion of a thin plate, a glass adhesive, and a ferrite plate. 1... Magnet head, 2, 2a to 2d,... Ferrite plate, 3, 3a, 3b... - Metal magnetic thin plate, 4.5...
・Glass adhesive, 7...gap, 13.16...
・Magnetic head block. Patent applicant Victor Company of Japan Co., Ltd. Figure 2 Nae wave number lo-3 Figure 8 @ 9 Figure procedure? fli official conspiracy November 12, 1985 i) 臘

Claims (3)

[Claims] (1) In a magnetic head having a composite structure in which a metal magnetic alloy material and a ferrite material are bonded together using a glass adhesive, the thermal expansion coefficient of the glass adhesive is equal to the thermal expansion coefficient of the metal magnetic alloy material. A magnetic head characterized in that the material is selected to have a value within the range of a value approximately equal to the smaller of the coefficients of thermal expansion of the ferrite material and a value 15% smaller than this value. (2) the metal magnetic alloy material is a Fe-Al-Si magnetic alloy, the ferrite material is MnZn ferrite,
The coefficient of thermal expansion of the glass adhesive is 110×10^-^7
2. The magnetic head according to claim 1, wherein the magnetic head is selected to have a value in the range of .about.130.times.10.about.7. (3) The metal magnetic alloy material and the ferrite material have a thermal expansion coefficient approximately equal to the smaller of the thermal expansion coefficient of the metal magnetic alloy material and the thermal expansion coefficient of the ferrite material, and 15% from this value. When bonding materials with a selected glass adhesive with a value within the range of a small value, when the glass adhesive is melted and then slowly cooled, the glass adhesive is 1. A method for manufacturing a magnetic head, comprising holding the agent at a temperature corresponding to the annealing point of the agent for a predetermined period of time.