JPH0580044B2 - - Google Patents

Description

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

Conventional technology Conventionally, magnetic heads have been constructed by using soft magnetic permalloy, sendust, amorphous alloy, Mn-Zn-ferrite, etc. as the magnetic core material, and bonding or adhering this to a substrate, or depositing it on the substrate.・
Materials formed by sputtering, CVD, plating, etc. have been used.

In a magnetic head with such a configuration, unless the soft magnetic material and the substrate material have the same coefficient of thermal expansion, or the difference between them is extremely small, stress will be generated at the interface between the two materials due to temperature changes, causing cracks. or the magnetic properties of the soft magnetic material deteriorate due to the magnetostrictive effect. For this reason, a substrate material whose thermal expansion coefficient can be freely changed according to the type and composition of the soft magnetic material used is required, such as crystallized glass, CaO-SrO- _TiO2 ceramic substrates (Japanese Unexamined Patent Publication No. 52-57218),
NiMnO ₂ ceramic substrates (Japanese Unexamined Patent Publication No. 16399/1983) were used. The coefficient of thermal expansion of these substrate materials can be selected from a wide range by adjusting the composition.

Problems to be solved by the invention However, crystallized glass and CaO−SrO−
Since TiO ₂ -based substrates contain alkali metals or Ca as components, they are chemically unstable against environmental conditions during use, especially changes in humidity, and when a magnetic head is constructed using these substrates, There were problems with weather resistance and durability. on the other hand,
When using a NiMnO ₂ -based substrate, there is no problem with temperature changes, but since MnO is easily oxidized to Mn ₂ O ₃ when heated in air, it may not have sufficient thermal stability. In addition, the manufacturing cost is high because the firing atmosphere must be non-oxidizing for the substrate itself, and NiO
Due to the large difference in lattice constant between MnO and MnO, it is difficult to form a solid solution, resulting in poor sinterability.

Means for Solving the Problems In order to solve the previous problems, the present invention has a rock salt type crystal structure and a complex oxide Mg _x Ni _1-x O (0<x<
This magnetic head is characterized in that it uses a substrate containing 1) as a main component, and a soft magnetic material is formed as a magnetic core on this substrate.

As a result of research, the inventors have developed a product with excellent moisture and heat resistance.
It has been found that by dissolving MgO in NiO, the coefficient of thermal expansion can be adjusted within the range of 100 to 140 x 10 ^-7 /°C. MgO is soluble 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, a magnetic head constructed using this Mg _x Ni _1-x O substrate has excellent weather resistance and durability characteristics. Regarding the substrate material itself, the difference in lattice constant between NiO and MgO is small, so 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, mixed in a wet ball mill for 16 hours, and then dried at 150℃ to determine the molar ratio of NiO and MgO.
NiO:MgO=1:0, 4:1, 2:1, 1:1,
Mixed powders of 1:2, 1:4, and 0:1 were obtained. Add 10% by weight of pure water to this mixed powder, granulate it, and
Uniaxial pressure molding was carried out in a mold at a pressure of Kg/cm ² . This formed body was placed in a SiC mold using alumina as a pressure medium, and hot pressed at a temperature of 1100°C to 1500°C and a pressure of 300 kg/cm ² for 2 hours. The obtained sintered body was subjected to phase identification using X-ray diffraction, density measurement using Archimedes method, and particle size observation using a scanning electron microscope.
A sample was cut out and measured at 25℃ to 400℃ using a thermal dilatometer.
The coefficient of thermal expansion was measured between As a result, X-ray diffraction showed a rock salt-type crystal structure diffraction pattern for all samples, which confirmed that the sintered body was Mg _x Ni _1-x O (0<x<1). Ta. The density measurement results varied depending on the mixture of NiO and MgO, but in all samples, the density was 99.5% 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 as observed using a scanning electron microscope. As shown in Figure 1, the coefficient of thermal expansion is 140×10 ^-7 for single oxides MgO and NiO.
degree and maximum, and minimum 100× for Mg _1/2 Ni _1/2 O
10 ^-7 /°C, and it varied continuously between them.

Therefore, Mg _1/5 whose thermal expansion coefficient is 120×10 ^-7 /℃
A sintered body of Ni _4/5 O (MgO:NiO=1:4) was selected, cut and polished to obtain a substrate with a surface smoothness R _nax of 0.1 μm. This substrate has a thermal expansion coefficient of 120×10 ^-7 /
A magnetic head as shown in Fig. 2 was fabricated from a soft magnetic amorphous alloy containing Co as a main component at a temperature of 1.5°C. In Figure 2, 1 is the board, 2 is the magnetic gap, and 3
4 is an amorphous metal magnetic film, and 4 is a window for winding.

To explain the process of creating a magnetic head, an insulating layer mainly composed of SiO ₂ 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 in thickness. A substrate is attached on top of this using an inorganic adhesive, and a second
Make A and B in the diagram. A groove is formed in B to serve as a window for the winding wire No. 5, and gap forming glass is sputtered to the magnetic gap forming surfaces of both parts A and B. Finally, parts A and B are hot bonded. do.
This bonded body is wound with wire to form a magnetic head.

In addition to the magnetic head using the Mg _1/5 Ni _4/5 O substrate prepared in this way, for comparison, crystallized glass with a thermal expansion coefficient of 120 × 10 ^-7 /°C and CaO-
Magnetic heads were prepared in the same manner using SrO-TiO ₂ ceramics as substrates. 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/sec to improve the head's output changes, wear resistance, and environmental resistance. I tested the gender. As a result, under normal environment, 23℃, humidity
At 50%, there were no particular differences in magnetic head characteristics depending on the type of substrate, but under environmental conditions of 23°C and 10% humidity, crystallized glass and CaO-SrO-
In a magnetic head using a TiO ₂ -based ceramic as a substrate, it was observed that the head output decreased by several dB within a few 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 surface of the substrate, creating irregularities. On the other hand, such adhesion did not occur on the Mg _1/5 Ni _4/5 O 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 _, and low temperature and high humidity. There were no problems with wear resistance, and stable characteristics were exhibited. 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 perspective 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, causing 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 120×10 ^-7 /
℃ is used, but the soft magnetic material is not limited to this, and as long as its coefficient of thermal expansion is within the range of 100×140×10 ^-7 /℃, it can be By changing the solid solution ratio of NiO and MgO, an optimal substrate can be provided. Furthermore, the method of manufacturing the magnetic head is not limited to the method described in the embodiments.

As is clear from Figure 1, the coefficient of thermal expansion is 100
The compositions that give ~104×10 ^-7 /℃ are the side with more NiO (0<x<0.5) and the side with more MgO (0.5<x<1)
However, if you have to choose between the two, it is better to choose the side with more NiO. This is because the more NiO there is, the lower the sintering temperature is, and the more MgO there is, the more moisture resistance may become a problem. Moreover, the substrate material used in the present invention has Mg _x Ni _1-x O as a main component,
Addition of additives to improve machinability or sintering properties does not cause any problems.

Effects of the Invention The present invention is a magnetic head using a substrate mainly composed of Mg _x Ni _1-x O (0<x<1) and having an adjusted coefficient of thermal expansion. It has stable performance without any problems, and has excellent environmental resistance and wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the thermal expansion coefficient of Mg _x Ni _1-x O-based material and the value of the composition ratio x, and FIG. 2 is a diagram showing an example of the magnetic head according to the present invention. 1... Substrate, 2... Magnetic gap, 3... Amorphous metal magnetic film, 4... Winding window.

Claims (1)

[Claims] 1 Composite oxide Mg _x with rock salt type crystal structure
A magnetic head characterized in that it uses a substrate mainly composed of Ni _1-x O (0<x<1) and has a soft magnetic material formed as a magnetic core on the substrate.