JPH0815360A - Mr snesor - Google Patents

Abstract

PURPOSE:To obtain an MR sensor which can detect even a small chip of a board electrically and automatically. CONSTITUTION:Magnetoresistive effect elements 10a-10d are formed on a board 15 and terminals 12a-12e are provided at the opposite ends and between respective elements. The central terminal 12c is employed as a power supply terminal, the opposite end terminals 12a, 12e as ground terminals, and the intermediate terminals 12b, 12d as output terminals thus constituting a two-phase MR position sensor 1. A chip detection wiring 13 is laid along the periphery of the board 15 between the ground terminals 12a, 12e. The terminals 12a, 12e are short- circuited when the chip detection wiring 13 is conducting and a predetermined resistance appears between the terminals 12a, 12e if they are open-circuited due to chipping of the board. When probes 41a, 41b are brought into contact with the terminals 12a, 12e and the resistance between the terminals is measured by means of a resistance meter 40, even a small chip of the board 15 can be detected electrically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive sensor (hereinafter referred to as an MR sensor), and more particularly to an MR sensor having a structure capable of automatically inspecting a defect in a substrate.

[0002]

MR utilizing the change in resistance value due to magnetic field
Sensors are often used, for example, as displacement sensors such as position sensors. Such an MR sensor is illustrated in FIG. FIG. 4 shows a position sensor using a magnetoresistive effect element. The MR sensor 9 includes four magnetoresistive effect elements 90a to 90d on a glass substrate 95.
Are formed and are connected by the wiring 91. The magnetoresistive effect elements 90a to 90d and the wiring 91 are covered with a protective film (not shown). Further, electrode terminals 92a to 92e, which are connection terminals to the outside, are provided between the magnetoresistive effect elements 90a to 90d and at both ends. The resistance values of the magnetoresistive effect elements 90a to 90d are detected from the terminals 92a to 92e. This MR
The size of the sensor 9 is about 5 mm × 5 mm.

In such a method for manufacturing an MR sensor, a large number of MR sensors are collectively formed on one substrate,
It is done by cutting into individual sensors after completion. Each of the cut sensors is used for various devices as a finished product after inspecting its conduction state and resistance value. However, in this cutting step, since the substrate 95 is made of glass, it may be cracked or chipped at a portion other than the predetermined cutting position. For example, in FIG.
A defect such as a defect 96 and a defect 97 shown in the MR sensor 9 is generated. For that purpose, the cut MR sensor needs to be inspected for proper cutting and for such defects.

When the above-mentioned inspection is performed, for example, a defect 96
As described above, when the defect of the substrate reaches the wiring 91 or the magnetoresistive effect element 90d, the MR sensor 9 does not operate normally, so it is necessary to exclude it as a defective product. Since such a defect affects the conduction state and resistance value of the MR sensor 9, it can be found by an electrical inspection and an automatic inspection is possible. On the other hand, a relatively small defect such as the defect 97 that does not reach the wiring 91 or the magnetoresistive effect element 90a does not affect the conduction state or the resistance value, and thus this MR sensor operates normally during manufacturing. However, in such an MR sensor, moisture or the like easily penetrates through the gap between the substrate and the protective film, and there is a high possibility that the characteristics will change or the durability time will be shortened with the passage of time. Therefore, the MR sensor having such a relatively small defect needs to be rejected as a defective product. Such a defect cannot be found by an electrical inspection, and the MR sensor having such a defect cannot be automatically removed. Therefore, an operator visually inspects the defect.

[0005]

However, the above-described checking of the MR sensor defect by the operator's visual observation has problems in terms of both efficiency and accuracy. That is, 5
This work of checking a large amount of defects in the MR sensor having a small size of about 5 mm × 5 mm imposes a great burden on the operator. Further, since it is a visual inspection, there is a possibility that a defective product may be overlooked.

Therefore, an object of the present invention is to provide an MR sensor having a structure capable of automatically and accurately detecting a defect of the MR sensor substrate material generated during the manufacturing process, not by visual inspection by an operator. is there.

[0007]

In order to automatically perform the above-mentioned inspection, a detection member capable of electrically detecting a defect of the substrate is provided along the periphery of the substrate of the MR sensor, and the output of the detection member is automatically detected. Electrical inspection. As the detecting member, a member that becomes defective when the substrate is damaged, has a simple structure, is inexpensive, and is easy to install is desirable. Furthermore, it is common with components such as MR sensor elements and wiring,
Alternatively, a similar member is desirable.

Therefore, the MR sensor of the present invention comprises a substrate, a magnetoresistive effect element formed on the substrate, a first connecting portion for measuring its resistance value from the outside, and the magnetoresistive effect element. And a wiring for connecting the first connecting portion, and a conductive thin film strip closely attached to the peripheral edge of the substrate for electrically detecting a defect in the substrate. Specifically, the MR sensor of the present invention has a configuration in which second connecting portions for externally detecting the conductive state of the conductive thin film state are provided at both ends of the conductive thin film strip. Further, specifically, the first connection portion has two or more terminals that are maintained at the same reference potential, and these two terminals are used for externally detecting the conductive state of the conductive thin film state. It is also configured to be used as the connection portion of 2. Further, it is preferable that the conductive thin film strip and the second connecting portion are formed simultaneously with the magnetoresistive effect element, the first connecting portion and the wiring.

[0009]

If the substrate is damaged at the time of manufacturing the MR sensor, the conductors closely attached along the peripheral edge of the substrate are also damaged. That is, the conductor is cut. Therefore, if the conductive state of the conductor is checked from both ends of the conductor, the defect of the substrate can be electrically detected automatically.

[0010]

EXAMPLES Referring to FIG. 1 and FIG. 2 will be described MR sensor of the first embodiment of the first embodiment the present invention. FIG. 1 is a diagram showing the configuration and inspection method of the MR sensor of the first embodiment. The MR sensor 1 includes a substrate 15 and magnetoresistive effect elements 10a-10.
d, wiring 11, terminals 12a to 12e, and loss detection wiring 13.

The structure of each part will be described below. The substrate 15 is a glass substrate for forming each element that constitutes the MR sensor 1. The substrate 15 of this embodiment has about 5 sides.
It is a square substrate of about mm. Magnetoresistive element 10
Reference symbols a to 10d are magnetoresistive effect elements whose resistance values change according to the application of a magnetic field. In this embodiment, permalloy, which is a magnetic alloy of nickel (Ni) and iron (Fe),
It is formed to be sufficiently thin so as to have a predetermined resistance value. The magnetoresistive effect elements 10a to 10d are formed on the substrate 15 in parallel with each other with a predetermined interval therebetween. Wiring 11
Is wiring for electrically connecting the magnetoresistive effect elements 10a to 10d and the terminals 12a to 12e. The magnetoresistive effect elements 10a to 10d are sequentially connected, and further, the terminals 12a to 12e are wired from both ends of the magnetoresistive effect elements 10a to 10d and between the elements. The wiring 11 is a magnetoresistive effect element 10a-1.
The same permalloy as 0d is formed with a predetermined width sufficient to make its resistance value negligible.

The terminals 12a to 12e are connection terminals for applying a voltage to the magnetoresistive effect elements 10a to 10d from the outside and measuring the resistance value, and are formed of copper plates in this embodiment. The terminals 12a and 12e are provided at both ends of the magnetoresistive effect elements 10a to 10d, respectively.
Reference numerals 12c and 12d denote magnetoresistive effect elements 10a to 10 respectively.
It is provided between d. The defect detection wiring 13 is the substrate 1
The wiring is provided along the peripheral edge of the substrate 5 so as to be in close contact with the substrate 15. It is a wiring for detecting a defect of the provided substrate 15. In this embodiment, like the wiring 11, it is formed of permalloy having a predetermined width such that the resistance value is sufficiently small. In addition, the defect detection wiring 13
Both ends of are connected to a terminal 12a and a terminal 12e. Therefore, the terminals 12a and 12e are short-circuited.

As described above, the magnetoresistive effect elements 10a to 10d, the wiring 11, and the defect detection wiring 13 of the MR sensor 1 are all formed of permalloy. In this embodiment, these parts are formed simultaneously by vapor deposition. The film thickness of each of these parts is about several tens of nm.
In addition, a portion of the substrate 15 excluding the terminals 12a to 12e is covered with a resin (not shown), whereby the magnetoresistive effect elements 10a to 10d, the wiring 11, and the loss detection wiring 13 are shielded from the outside and protected. Has been done.

Next, a method of using the MR sensor 1 will be described with reference to FIG. FIG. 2 shows the MR sensor 1
It is a figure explaining the usage pattern of, and is a figure showing the state where flexible substrate 30 is provided in MR sensor 1. The MR sensor 1 is provided with a flexible substrate 30, and the terminals 12a to 12e of the MR sensor 1 are connected to the terminals 32a to 32d on the flexible substrate 30 by lead wires 31a to 31e.

In the MR sensor 1 of FIG. 2, the terminal 3
2c is used as a power supply terminal and terminal 32a is used as a ground terminal.
As a result, a two-phase type position sensor 1 having an A phase composed of the magnetoresistive effect elements 10a and 10b and a B phase composed of the magnetoresistive effect elements 10c and 10d is constituted. Then, the voltage division ratio of each magnetoresistive effect element in the A phase and the B phase can be detected from the output terminal 32b and the output terminal 32d. When the position of the external magnet changes, the magnetic field changes, and the magnetoresistive effect elements 10a-1
Each resistance value of 0d changes, and the voltage division ratio in each phase of A and B changes. Therefore, by detecting the output values of the output terminal 32b and the output terminal 32c, it becomes possible to detect the position, the moving state, and the like of the external object.

Next, a method of detecting a defect of the substrate 15 by the MR sensor 1 will be described. In the MR sensor 1 having such a configuration, the substrate 15 is examined by checking the conductive state of the loss detection wiring 13 from both ends of the loss detection wiring 13.
Can be detected. In other words, both ends of the loss detection wiring 13 are short-circuited if there is no loss, and the loss detection wiring 13 is disconnected when a loss occurs, so that both ends of the loss detection wiring 13 are insulated.

Further, in the MR sensor 1, the terminals 12a and 12e are finally short-circuited by the lead wire 31e on the flexible substrate 30 and used. Therefore, even if a short circuit occurs on the substrate 15 at the stage of manufacturing the MR sensor 1, the function of the MR sensor 1 can be obtained. Therefore, in the MR sensor 1 of the first embodiment, both ends of the defect detection wiring 13 provided along the peripheral edge of the substrate 15 are connected to the terminals 12a and 12b. Then, the resistance value between the terminals 12a and 12e is determined by the MR sensor 1
By measuring with the resistance measuring device 40 in a state in which is not connected to the flexible substrate 30, it is possible to detect a defect in the peripheral portion of the substrate 15. That is, if there is no defect, terminal 1
When 2a and the terminal 12e are short-circuited and a defect occurs,
The resistance value between the terminals is the magnetoresistive effect element 10a-1.
Values are shown as terminals at both ends of which 0d is connected in series.

Thus, the MR sensor 1 of the first embodiment
According to this, even a relatively small defect of the substrate of the MR sensor 1 can be electrically and automatically inspected. Furthermore, since the terminals at both ends of the defect detection wiring 13 for that purpose can also be used as terminals for measuring the resistance value, it is not necessary to increase the number of terminals, and the area of the MR sensor 1 can be reduced due to the addition of the defect detection wiring 13. It can prevent the increase.

[0019] With reference to FIG. 3 will be described MR sensor of the second embodiment of the second embodiment the present invention. The MR sensor 2 of the second embodiment has dedicated defect detection wiring terminals 24a and 24b for inspecting the conduction state of the defect detection wiring 13 at both ends of the loss detection wiring 13 of the MR sensor 1 of the first embodiment. The configuration is the same as that of the first embodiment except for the configuration provided. In this way, a configuration that does not have terminals that are maintained at the same potential
In the case of the MR sensor of the usage method, by providing the dedicated defect detection wiring terminals 24a and 24b, it becomes possible to detect the defect of the substrate 15 as in the first embodiment. Therefore, the defect of the present invention can be inspected for MR sensors of any structure.

The present invention is not limited to the first and second embodiments described above, and various modifications can be made. For example, in this embodiment, the magnetoresistive effect elements 10a to 10d, the wiring 11, and the defect detection wirings 13 and 23 are all formed by using Ni-Fe alloy permalloy as a material. However, the present invention is not limited to this, and a conductor such as a copper wire may be used as the wiring member. Further, as the material of the magnetoresistive effect element, another material for magnetoelectric element such as InSb or InAs may be used. Further, as the MR sensor of the present embodiment, a position sensor for detecting a linear displacement of an object in which four magnetoresistive effect elements are provided in parallel on the substrate has been exemplified. A rotation detection sensor or the like in which is arranged in a circular shape may be used. Further, the shape of the wiring, the position of the terminal, and the like may be arbitrary shapes and positions.

[0021]

According to the MR sensor of the present invention, even when a small substrate material which does not reach the wiring or the magnetoresistive effect element, which occurs during the manufacturing process of the sensor, is not visually observed by the operator, but is electrically detected. Automatically, efficiently and accurately.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration and an inspection method of an MR sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a flexible substrate is provided on the MR sensor shown in FIG.

FIG. 3 is a diagram showing a configuration of an MR sensor according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a conventional MR sensor and a defective state of a substrate.

[Explanation of symbols]

 1, 2 ... MR sensor 10a-10d ... Magnetoresistive element 11 ... Wiring 12a-12e ... Terminal 13, 23 ... Defect detection wiring 24a, 24b ... Defect detection wiring terminal 15, 25 ... Board 30 ... Flexible board 31a ... 31e ... Lead wire 32a-32d ... Terminal 40 ... Resistance measuring instrument 41a, 41b ... Probe 9 ... MR sensor 90a-90d ... Magnetoresistive effect element 91 ... Wiring 92a-92e ... Terminal 95 ... Glass substrate 96, 97 ... Defect

Claims (4)

[Claims] 1. A substrate, one or more magnetoresistive effect elements formed on the substrate, a first connecting portion capable of measuring a resistance value of the magnetoresistive effect element, and the magnetoresistive effect element. And an MR having wiring connecting the connecting portions, and a conductive thin film strip adhered to the peripheral edge of the substrate in order to electrically detect a defect in the substrate.
sensor. 2. The MR sensor according to claim 1, further comprising second connection portions at both ends of the conductive thin film strip for detecting a conductive state of the conductive thin film. 3. The first connecting portion has two or more terminals maintained at the same reference potential, and each of the two terminals is also used as the second connecting portion. M
R sensor. 4. The conductive thin film strip and the second connecting portion are formed on the substrate simultaneously with the formation of the magnetoresistive effect element, the first connecting portion and the wiring. The MR sensor according to any one of 3 to 3.