JPS6390014A - Production of composite magnetic head core - Google Patents

Abstract

PURPOSE:To minimize the residual stress in the joint surfaces of Mn-Zn ferrite and 'Permalloy(R)' by heating and pressurizing the joint surfaces while maintaining specific joining conditions at the time of joining said materials. CONSTITUTION:The Mn-Zn ferrite 11 to be formed as a coil winding part and the Fe-Ni alloy ('Permalloy(R)') to be formed as a tape contact part are laminated and are hermetically sealed into a platinum container 13. The container is heated and pressurized by using gaseous argon as a pressure medium while the joining conditions expressed by the formula are maintained. In the formula, alpha(1), alpha(2) are respectively the coeffts. of volumetric expansion of the 'Permalloy(R)' and the Mn-Zn ferrite, K(1), K(2) are respectively the rate of volumetric compression thereof, P is a gage pressure, T is a temp. deg.C and TR is an initial temp. As a result, the stress remaining on the joint surfaces is decreased to a negligible level and consequently the deterioration in the magnetic characteristics is prevented and the composite magnetic head core is obtd.

Description

Detailed Description of the Invention "Technical Field" The present invention relates to Mn-Zn ferrite and Fe-Ni alloy (
The present invention relates to a method of manufacturing a composite magnetic head core in which a core is obtained by joining (Permalloy), and particularly relates to a method of manufacturing a composite magnetic head core that does not have a joining layer of different materials at the joint and has a small amount of strain at the joint.

[Prior Art and its Problems] To compensate for the drawbacks of magnetic head cores made of a single material, an Ampex-type magnetic head core in which the tape contact portion and the coil winding portion are made of different materials has been proposed.

In a magnetic head constructed of this Acipex type magnetic head core, as shown in FIG. are brought together at two places, and a head gap 4 is formed at the joining part of the tape contacting part 2 with a non-magnetic material in between, and a pack gap 5 is formed at the other joining part with a non-magnetic material in between. . Then, the head gap 4 of the tape contact portion 2 comes into direct contact with the magnetic tape 6 to perform writing and reading of magnetic recording. In the magnetic head core of such a magnetic head, it is known that Mn--Zn ferrite is used for the coil winding portion 1 and Fe--Ni alloy (permalloy) is used for the tape contact portion 2.

Such a composite magnetic head core is manufactured by separately molding the tape contact portion 1 and the coil winding portion 2, and then bonding them together via an epoxy-based organic adhesive or an adhesive layer such as glass. However, since the adhesive layer used here is a non-magnetic material or has an extremely low magnetic permeability, it creates a large resistance and has a considerable effect on the magnetic circuit.
In addition, due to variations in the thickness of the adhesive layer, the tape contact area 1
In other words, it is a direct cause of variations in the characteristics of the head chips.

Further, in the method of joining the tape contact portion 1 and the coil winding portion 2 via a metal layer on the joining surface (metallization method), there is a problem in corrosion resistance near the joining surface, and magnetic circuit loss is likely to occur.

In view of the fact that the cause of these problems is the interposition of a layer of different materials on the joint surface, recently a method has been proposed to join the two without intervening a layer of different materials on the joint surface. There is. In this method, the Mn which becomes the coil winding part 1 is
-Fe-Ni which becomes Zn ferrite and tape contact part 2
A composite magnetic head core is manufactured by bringing fi-alloy (permalloy) into contact with the core and heating and pressurizing the entire core.

However, according to this manufacturing method, since Mn-Zn ferrite and Fe-Ni alloy (permalloy) have different coefficients of thermal expansion, heating and pressure during bonding cause distortion in both, and this distortion causes damage to the bonded surface. Residual stress is generated in the joint, which changes the properties of the joint. As a result, the reliability of the bonding surface is reduced.

``Purpose of the Invention'' The present invention has been made to solve the above-mentioned problems. The object of the present invention is to provide a method for manufacturing a head.

“Summary of the Invention” In the method for manufacturing a composite magnetic held according to the present invention, Mn-
This method was developed based on the fact that the cause of strain that occurs during bonding between Zn ferrite sintered bodies and Fe-Ni alloy (permalloy) sintered bodies is the difference in thermal expansion coefficient between the two.
When joining the Mn-Zn ferrite sintered body that will become the coil winding part and the Fe-Ni alloy (permalloy) sintered body that will become the tape contact part, the temperature is increased while pressurizing isotropically using a fluid as a pressure medium. , is characterized in that after being held for a certain period of time under bonding conditions that have the relationship between temperature and pressure shown in the following equation, the temperature and pressure are lowered while maintaining the temperature and pressure conditions shown in the following equation.

However, α(1) is the coefficient of body expansion of Fe-Ni alloy (permalloy), α(2) is the coefficient of body expansion of Mn-Zn ferrite,
K(1) is the body compressibility of Fe-Ni alloy (par?[]i), ni(2) is the body compressibility of Mn-Zn ferrite, P is the gauge pressure (K9 f/cm'), and T is Temperature (℃), T
R represents the initial temperature (°C).

“Embodiments of the invention” Examples of the present invention will be described in further detail below.

The Mn-Zn ferrite used in the present invention is Fe
20345-60 mol%, Mn020-45 mol%, Z
The composition ranges from nO3 to 30 mol%. Also, F
e-Ni alloy (permalloy) is Fe12-14.5
% by weight, and the balance is made of Ni, or in order to improve the properties of the alloy, Mo, Mn, and S are added as alloy components.
One or more of i, Nb, Cr, W! The content is 0.1 to 5% by weight. The Mn--Zn ferrite sintered body and the Fe--Ni alloy (permalloy) sintered body are each cut into the size and shape to be joined, and then each is mirror-polished. After mirror polishing and ultrasonic cleaning with an organic solvent such as acetone, both plates are stacked and brought into close contact. The tightly attached sample is placed in a capsule, deaerated, and then the capsule is sealed.

This capsule is heated isotropically using a fluid as a pressure medium while being pressurized, and after being held for a certain period of time under bonding conditions that have the relationship between temperature and pressure as shown in the equation below, the temperature and pressure also rise as shown in the equation below. By lowering the temperature and applying high pressure while maintaining the pressure relationship, a sintered body of Mn-Zn ferrite and a Fe-Ni alloy (
permalloy) is manufactured.

where α(1) is the coefficient of body expansion of Fe-Ni alloy (permalloy), α(2) is the coefficient of body expansion of Mn-Zn ferrite,
K(1) is the body compressibility of Fe-Ni alloy (permalloy), K(2) is the body compressibility of Mn-Zn ferrite, P is gauge pressure (K9 f/cm'), T is temperature (℃) , T.R.
represents the initial temperature (°C).

The principle of the present invention is that the difference in expansion rate that occurs between the two during heating is
The purpose is to offset the difference in compressibility caused by applying isotropic pressure. Therefore, when increasing the temperature and pressure to the bonding conditions, it is not necessary that the above formula be satisfied. Furthermore, the bonding temperature does not need to satisfy the above formula, and may be set slightly higher. However, it is necessary to maintain the bonding condition for a certain period of time under bonding conditions that satisfy the above formula. What is important in the present invention is when the temperature and pressure are lowered from the bonding conditions, and if these conditions are deviated from at this time, stress will occur at the bonding surface between the two.

According to the method of the present invention, the difference f!, which was a problem with conventional diffusion bonding, etc. ! The stress and strain on the bonding surface due to the difference in the coefficient of thermal expansion of the bonding materials is suppressed to a negligible level, and no deterioration in magnetic properties is observed. Furthermore, variations in magnetic properties due to variations in the thickness of the bonding layer when the two are bonded using a bonding layer are also eliminated.

Example 1゜Fe20354 mol%, Mn027 mol%, Zn019
Mn-Zn ferrite with mol%, body expansion rate of 382 x 10-7/°C, body compression rate of 5.8 x 10-'crn'/, 9f of Mn, 81% by weight of Ni, 14% by weight of Fe,
Additives such as Nb, body expansion rate 375x 10-
Each sintered body of Fe-Ni alloy (permalloy) with a temperature of 9F and a body compression rate of 6.8 x 10-7 cmr/°C was cut into a disc-shaped plate with a diameter of 10 mm and a thickness of 1 mm. Mirror polish each surface. After that, after washing with an organic solvent or the like, both sides are brought together and sealed.

This sample is placed in a platinum container with a wall thickness of 0.2 mm, and after degassing, the container is sealed. The platinum capsule made in this way was attached to a pressurized heating device using argon as a pressure medium.
After holding for 1 hour at 20°C and 7700 gf/cri', P = 7. Ox (T -20) (However, ■ is °C, P is qf/c%, initial temperature is 20 °C
) While maintaining the pressure so as to satisfy the conditions, the temperature was lowered at a rate of 5° C. per minute, and the temperature and pressure were lowered to room temperature and pressure. Here, it is preferable that the bonding temperature is high, but Fe-Ni
It must be lower than the melting point of the alloy (permalloy).

The thus obtained Mn-Zn ferrite and Fe-
When the bonded surface of the Ni-based alloy (permalloy) bonded body was observed with a cut and polished surface perpendicular to the bonded surface, no pores or altered layers were found.

Example 2 Using the same proportions of materials as in Example 1, a cylindrical block was formed to have a diameter of 10 mm and a thickness of 10 mm for the Mn-Zn ferrite 11, and for the Fe-Ni alloy (permalloy) 12. , using disc-shaped plates molded to have a diameter of 10 mm and a thickness of 1 mm, mirror polish the surface of each plate, wash with an organic solvent, and then replace the Mn-Zn ferrite 11 with Fe.
- Laminated with Ni-based alloy (permalloy) 12,
It is placed in a platinum container 13 with a wall thickness of 0.2 mm, and after being evacuated, it is sealed. The platinum capsule made in this way was attached to a pressurized and heated mine using argon as a pressure medium.
90 at 50°C and 7210 qf/crn'
Hold for minutes. Then P = 7. Ox (T-2
0) (However, T is °G, P is 9f/cm, and initial temperature is 20°C) while lowering the temperature and pressure at a rate of 5°C per minute to bring the temperature and pressure to room temperature and normal pressure. Lowered.

The thus obtained Mn-Zn ferrite and Fe-
When a bonded body of Ni-based alloy (permalloy) was evaluated in the same manner as in Example 1, effects similar to those in Example 1 were obtained.

"Effects of the Invention" As explained above, according to the present invention, the difference in expansion coefficient that occurs during heating of sintered bodies of Mn-Zn ferrite and Fe-Ni alloy (permalloy) can be compensated for by using fluid as a pressure medium. This is offset by the compression difference created by applying isotropic pressure to both materials, so the stress strain on the joint surface due to the difference in thermal expansion coefficient of the dissimilar joining materials is suppressed so small that it can be ignored.
A composite magnetic head core with good magnetic properties can be manufactured.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a sample in Example 2 that was laminated to be sealed in a container during the manufacturing process according to the method of the present invention, and Figure 2 is an external view of a platinum container used in the method of the present invention in Example 2. , FIG. 3 is a front view of a general magnetic head constructed of an Ampex type magnetic head core. DESCRIPTION OF SYMBOLS 1... Coil winding part, 2... Tape contact part, 11.
...Mn-Zn noelite sintered body, 12...Fe-N
i-based alloy (permalloy) sintered body, ]3...Platinum container. Patent applicant Alps Electric Co., Ltd. Agent
Kunio Miura Shigeru Matsui

Claims (1)

[Claims] (1) Mn-Zn ferrite sintered body that becomes the coil winding part and Fe-Ni alloy (permalloy) that becomes the tape contact part
In a method for manufacturing a composite magnetic head core in which sintered bodies are brought into contact with each other and heated and pressurized to join them together, the temperature is raised while pressurizing fluid isotropically as a pressure medium, and the relationship between temperature and pressure is expressed by the following formula. After maintaining the bonding conditions for a certain period of time, the temperature is lowered while maintaining the temperature and pressure conditions shown in the formula below.
A method for manufacturing a composite magnetic head core characterized by voltage step-down. P={[α(2)-α(1)]/[k(2)-k(1)
]}×(T-T_R) However, α(1) is the coefficient of body expansion of Fe-Ni alloy (permalloy), α(2) is the coefficient of body expansion of Mn-Zn ferrite, and k(1) is the coefficient of body expansion of Fe-Ni alloy. The body compressibility of the alloy (permalloy), k(2) is the body compressibility of Mn-Zn ferrite, P is the gauge pressure (Kgf/cm^2), T
represents the temperature (°C), and T_R represents the initial temperature (°C).