JPH05335652A - Ferromagnetic magnetic resistance element - Google Patents

Abstract

PURPOSE:To enable a thin-film magnetic resistance element to be used within gas oil and heavy oil and further provide a sealing structure for improving mechanical strength and reliability. CONSTITUTION:A ferromagnetic magnetic resistance element substrate 11 is laid out within a cap 12, the opening of the cap 12 is hermetically sealed, further the inside is replaced by inactive gas atmosphere or is turned into vacuum state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic magnetoresistive element using a nickel alloy ferromagnetic thin film.

[0002]

2. Description of the Related Art At present, among the rotation detection devices mainly used, an optical rotation detection device using an optical semiconductor and a magnetic rotation detection device using a Hall IC have a heat resistant temperature of 125.
The temperature is below ℃, which is a major obstacle to use in industrial equipment. Therefore, the use of ferromagnetic magnetoresistive elements having a heat resistant temperature of 200 ° C. or higher is increasing in industrial equipment. Especially in the electrical component field,
Many electronic components are required to have heat resistance of 180 ° C or higher, and it is clear from the physical properties of the detector that it is not possible to use a rotation detector other than the ferromagnetic magnetoresistive element, and its expectation is increasing. .. Furthermore, even in applications where heat resistance is not particularly required, if the environment of use is in light oil or heavy oil, or if there is a significant amount of dust, the colored liquid or dust may block the transmission of light rays. It was impossible to use the optical rotation detection device because of the hindrance.

On the other hand, a ferromagnetic magnetoresistive element has a film thickness of about 500 made of nickel alloy on a glass or ceramic substrate.
The ferromagnetic thin film of Å is patterned, and the protective film Si is formed on it.
It is formed by coating N with epoxy resin or polyimide resin.

FIG. 4 is a sectional view of a conventional ferromagnetic magnetoresistive element substrate. Here, 1 is a lead wire, 2 is a glass or ceramic substrate, 3 is a ferromagnetic magnetoresistive thin film, 4 is an electrode, and 5 is a protective film.

The ferromagnetic magnetoresistive element is constructed as shown in FIG. Here, 6 is a ferromagnetic magnetoresistive element substrate,
7 is a mold resin such as epoxy.

The ferromagnetic magnetoresistive element made of these materials has been extremely difficult to use in an environment containing a lot of humidity, in light oil or heavy oil, due to the characteristics of the constituent materials.

FIG. 2 shows the amount of change in the midpoint potential of these conventional ferromagnetic magnetoresistive elements due to continuous use in light oil. It can be seen that the voltage shifts to the negative side by 20 mV or more when 5 V is applied for 1000 hours. ..

FIG. 3 shows the rate of change in resistance value due to continuous use in light oil, which shows that the resistance value has decreased by 10% or more after 1000 hours.

[0009]

The causes of the problems of the above-mentioned conventionally used substrates are considered as follows.

1. Diffusion of alkaline components or halogen molecules contained in light oil or heavy oil into nickel alloy by electrophoresis.

2. Destruction of protective film resin by light oil or heavy oil. In view of the above problems, it is possible to provide a ferromagnetic magnetoresistive element that enables continuous use in a liquid that can corrode or destroy elements such as light oil and heavy oil, and that has higher mechanical strength and reliability. The purpose is to do.

[0012]

In order to solve the above problems, the present invention provides a ferromagnetic alloy magnetoresistive thin film of nickel alloy formed on the surface of a substrate made of ceramic or glass,
A ferromagnetic magnetoresistive element substrate having a protective film covering the ferromagnetic magnetoresistive thin film and a lead wire is provided, and the ferromagnetic magnetoresistive element substrate is disposed in a metal case having an opening, and A lead wire is drawn out from the opening, and the opening is hermetically sealed.

[0013]

[Function] The ferromagnetic magnetoresistive element is put in a metal cap, welded and sealed, and the lead-out portion is hermetically sealed with a low-temperature baked glass to completely eliminate contact with the outside air and prevent deterioration of the element. ..

[0014]

EXAMPLE A ferromagnetic magnetoresistive element according to an example of the present invention will be described below. In FIG. 1, 11 is a ferromagnetic magnetoresistive element substrate, which has a structure as shown in FIG. 12 is a copper alloy cap as a metal case, 13 is a lead wire,
Reference numeral 14 is an iron alloy base, and 15 is sealing glass. Here, the lead wire 13 and the base 14 are sealed with the glass 15 for sealing.
Then, the electrode portion of the ferromagnetic magnetoresistive element substrate 11 is welded or soldered to the tip portion of the lead wire 13. Then, the cap 12 is covered and the contact portion with the base 14 is welded or soldered. The inside of the cap 12 is filled with argon, nitrogen, or an inert gas that is very difficult to activate, or is placed in a vacuum state.

FIG. 2 shows the results of the amount of midpoint potential drift after continuous use in heavy oil at 100 ° C. using the device of this example, where the horizontal axis represents time and the vertical axis represents midpoint potential. The amount of drift is shown. According to this, it can be seen that the middle point does not troffer at all as compared with the conventional element only or the resin-molded ferromagnetic magnetoresistive element. This is because the metal cap, the base and the welded part are completely sealed,
This is because the deterioration of the ferromagnetic thin film and the destruction of the mold resin due to the impurity ions in the heavy oil have not occurred.

FIG. 3 shows the results of the rate of change in resistance value after continuous use in heavy oil at 100 ° C. using the device of this example, the horizontal axis represents time, and the vertical axis represents the rate of change in resistance value. ing.
According to this, it can be seen that there is no change in the resistance value.

[0017]

As described above, according to the present invention, the following effects can be obtained. 1. There is no midpoint potential drift in continuous use in heavy oil at 100 ° C. 2. There is no change in resistance value in continuous use in heavy oil at 100 ° C. 3. The mechanical strength of the element is increased. 4. The reliability of the element can be secured.

[Brief description of drawings]

FIG. 1 is a sectional view of a ferromagnetic magnetoresistive element according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the amount of change in the midpoint potential of the example and the conventional example.

FIG. 3 is a characteristic diagram showing resistance value change rates of the example and the conventional example.

FIG. 4 is a sectional view of a ferromagnetic magnetoresistive element substrate.

FIG. 5 is a sectional view of a conventional ferromagnetic magnetoresistive element.

[Explanation of symbols]

 11 Ferromagnetic Magnetoresistive Element Substrate 12 Cap 13 Lead Wire 14 Base 15 Sealing Glass

Claims (2)

[Claims] 1. A ferromagnetic alloy magnetoresistive thin film of nickel alloy formed on the surface of a substrate made of ceramic or glass,
A ferromagnetic magnetoresistive element substrate having a protective film covering the ferromagnetic magnetoresistive thin film and a lead wire is provided, and the ferromagnetic magnetoresistive element substrate is disposed in a metal case having an opening, and A ferromagnetic magnetoresistive element in which a lead wire is drawn out from the opening and the opening is hermetically sealed. 2. A ferromagnetic magnetoresistive element in which the atmosphere in a hermetically sealed metal case is an inert gas atmosphere or a vacuum state.