JPS61192005A - Magnetic head - Google Patents

Abstract

PURPOSE:To provide a magnetic head which has stable performance in sliding with a magnetic recording medium and is highly resistant to environment and wear by using a substrate having rock salt type crystal structure and consisting essentially of composite oxide MgxNi1-xO (O<X<1) and forming a soft magnetic material as a magnetic core on such substrate. CONSTITUTION:Pure water is added to a powder mixture composed of NiO and MgO and the mixture is granulated. The granules are uniaxially molded under the pressure in a metallic mold. The molding is put into an SiC mold and is hot-pressed with alumina as a pressure medium. The sintered body obtd. in the above-mentioned manner is cut and ground to form the substrate 1 having 0.1mum surface smoothness Rmax. The magnetic head is manufactured of the substrate 1 and a soft magnetic amorphous alloy consisting essentially of Co.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in the structure of a magnetic head.

Conventional technology Conventionally, magnetic heads have been constructed using soft magnetic permalloy, sendust, amorphous alloy, and Mn as magnetic core materials.
-Zn-ferrite or the like has been used, and it has been bonded or adhered to a substrate, or formed on the substrate by methods such as vapor deposition, sputtering, CVD, and plating.

In a magnetic head with such a configuration, unless the thermal expansion coefficients of the soft magnetic material and the substrate material are equal or the difference is extremely small, stress will be generated at the interface between the two materials due to temperature changes, causing cracks. Or is it due to magnetostrictive effects?
The magnetic properties of the soft magnetic material deteriorate. Therefore, there is a need for a substrate material whose thermal expansion coefficient can be freely changed depending on the type and composition of the soft magnetic material used. JP-A-62-57218), N
iMnO2 ceramic substrate (JP-A-53-16399
Publications) etc. were used. These substrate materials are
By adjusting the composition, the coefficient of thermal expansion can be selected within a wide range.

Problems to be Solved by the Invention However, crystallized glass and CaO-SrO-Ti
In the 02 series substrate, alkali metal or C is used as a component.
Since these substrates contain a, they are chemically unstable against environmental conditions during use, especially changes in humidity, and when a magnetic head is constructed using these substrates, problems have arisen regarding weather resistance and durability. -10,000, NiMnOz-based Jl (When using a plate, there is no problem with temperature changes, but
When MnO is heated in air, it is oxidized and becomes Mn20. Thermal stability is insufficient because NiO and Mn tend to be
Due to the large difference in the lattice constants of O, it is difficult to form a solid solution, resulting in poor sinterability.

Means for Solving the Problems In order to solve the above problems, the present invention uses a substrate having a rock salt type crystal structure and containing composite oxides MgxNi,xO(0(x×1)) as main components. This magnetic head is characterized by forming a soft magnetic material as a magnetic core on a substrate.

As a result of research, the inventors found that NiOI has excellent moisture and heat resistance.
By dissolving ICMgO, the coefficient of thermal expansion can be reduced to 1oO.
Did you find that it can be adjusted within the range of ~140 x 10-'/'C? MgO has solubility in water,
Although there is a problem in terms of moisture resistance, this point can be improved by forming a solid solution with NiO. Therefore, this MgxN
A magnetic head constructed using an i, -x O substrate has excellent weather resistance and durability characteristics. Regarding the substrate material itself, since the difference in lattice constant between NiO and MgO is small, it is easy to form a solid solution, and there is no need to particularly adjust the atmosphere during firing, so manufacturing is easy.

Example Examples are shown below.

Reagent grade nickel oxide and magnesium oxide were each weighed and mixed in a wet ball mill for 16 hours.
After drying at °C, the molar ratio of NiO and MgO was changed to NiO:M
g0=1:0.4:1.2:1.1 :1.1 :2,
A mixed powder of 1:4, 0:1 was obtained.

Add 10% by weight of pure water to this mixed powder, granulate it,
Uniaxial pressure molding was carried out in a mold at a pressure of 3ooKy/d.

This molded body was placed in a SiC mold using alumina as a pressure medium, and heated to 300°C at a temperature of 110°C to 15°C.
The sintered body obtained by hot pressing for 2 hours at a pressure of A sample of 6 mm x 5 ff x 101 tII was cut out from the sintered body, and the thermal expansion coefficient was measured using a thermal expansion needle between 25°C and 400'Q. As a result, X-ray diffraction showed a diffraction pattern of a rock salt type crystal structure in all samples, which suggests that the sintered body is MgxNi, x
It was confirmed that O(0(x<1).Also, the density measurement results change depending on the mixture of JNiO and MgO,
In all samples, the density was 99.6% or more of the theoretical density determined from X-ray diffraction. The grain size of the sintered body was found to be 5 to 10 μm when observed using a scanning electron microscope. As shown in Figure 1, the thermal expansion coefficient of single oxide MgO, NiO
The maximum value is about X 10-7/7C, and Mg%Ni%
The minimum value was 1oo x 10-7/c at O, and it changed continuously between them.

Therefore, a sintered body of MgZi, HO (MgO:NiO=1:a) with a thermal expansion coefficient of 120 x 10-7/AC was selected, cut and polished to obtain a surface smoothness of Rm1LX.
The substrate was 0.1 μm thick. A magnetic head as shown in FIG. 2 was fabricated using this substrate and a soft magnetic amorphous alloy containing CO as a main component and having a coefficient of thermal expansion of 120× 10 /'C. In Figure 2, 1 is the substrate, 2 is the magnetic gap, 3
4 is an amorphous metal magnetic film, and 4 is a window for winding.

To explain the process of making a magnetic head, an insulating layer mainly composed of 5i02 is formed to a thickness of about 1 μm on a well-cleaned substrate using a sputtering device, and then a soft magnetic amorphous alloy thin film is formed to a thickness of 30 μm. form it. A substrate is attached on top of this using an inorganic adhesive to create person B in Figure 2. A groove is formed in B to serve as a winding window for S, and gap forming glass is placed on the magnetic gap forming surfaces of both the human and B parts.
This is attached by sputtering, and finally the B part is hot-bonded, and wire is wound around this bonded body to form a magnetic head.

In addition to the Mgy, Ni440 magnetic head fabricated in this way, for comparison, the thermal expansion coefficient was 1.
20 x 1Q-7/=c crystallized glass and CaO
Magnetic heads were prepared in the same manner using -5rO-Ti02 ceramic as the substrate.

A so-called "metal tape", which uses metal magnetic powder as a magnetic recording medium, was slid against these three types of magnetic heads at a relative speed of approximately 3.8 m/sea, and the output change and wear resistance of the head were measured.・Tested environmental resistance. As a result, under the normal environment at 23°C and 50% humidity, there were no particular differences in the magnetic head characteristics depending on the type of substrate, but when the environmental conditions were 23°C and 10% humidity, crystallized glass and C& In a magnetic head using 0-3rO-TiO2 ceramic as a substrate, it was observed that the head output decreased by several dB several hours after the start of measurement. When these magnetic heads were closely observed, it was found that metal powder from the magnetic tape had adhered to the substrate surface, creating irregularities.

On the other hand, such adhesion did not occur in the "'A" AO substrate of the present invention, and therefore no reduction in the output of the magnetic head occurred. Similar tests were also conducted under other environmental conditions, such as high temperature and high humidity, high temperature and low humidity, low temperature and high humidity, and low temperature and low humidity. It did not cause any problems and exhibited stable characteristics. On the other hand, magnetic heads using other substrate materials have had problems such as decreased output and wear resistance as described above.

From the standpoint of wear resistance, substrate materials that wear too much are problematic, and if the crystal structure has anisotropy, the amount of wear will vary depending on the crystal orientation, which can cause unevenness on the substrate. It will be done. From this point of view, a substrate material whose crystal structure is a rock salt type satisfies the required characteristics.

In the above example, the coefficient of thermal expansion is 120X10-'/'
Although the case where an amorphous magnetic thin film of C is used is shown, the soft magnetic material is not limited to this, and the thermal expansion coefficient is 1.
If it is within the range of oo to 140 x 10'/'c, an optimal substrate can be provided by changing the solid solution ratio of NiO and MgO accordingly. Furthermore, the method of manufacturing the magnetic head is not limited to the method described in the embodiment.

As is clear from Figure 1, the coefficient of thermal expansion is 100 to 10.
The composition that gives 4 x 10-'/'C is the side with more NiO (o (x (o, s)) and the side with more MgO (o, s (x × 1)), but when choosing one, It is better to choose the side with more NiO.This is because the higher the NiO content, the lower the sintering temperature, and the higher the MgO content, the possibility of problems with moisture resistance. The substrate material used in the invention has MgxNi, -xO as its main components, and no problem will arise even if additives are added to improve machinability or sintering properties.

Effects of the Invention The present invention is a magnetic head using a substrate mainly composed of MgxNil-xO (0(x (1)) and having an adjusted coefficient of thermal expansion. It has stable performance and excellent environmental resistance and abrasion resistance.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the thermal expansion coefficient and the composition ratio X of MgxNil-xo based materials, and FIG. 2 is a diagram showing an example of a magnetic head according to the present invention. 1...Substrate, 2...Magnetic gap, 3
・・・・・・Amorphous metal magnetic film, 4・・・・・・
Winding window. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Rough diagram pCx-

Claims (1)

[Claims] Composite oxide Mg_xNi_1_ with rock salt type crystal structure
- A magnetic head characterized by using a substrate containing xO (0<x<1) as a main component and forming a soft magnetic material as a magnetic core on the substrate.