JP2022073444A - Bridge circuit built-in strain resistance element and manufacturing method thereof - Google Patents

Abstract

To provide a bridge circuit built-in strain resistance element having a monolithic structure in which a bridge circuit is achieved by one element and also to provide a method of manufacturing the same.SOLUTION: A bridge circuit built-in strain resistance element includes: a substrate; an electrode formed on the substrate; and a resistance film electrically connected to the electrode. At least one of the resistance films is a strain-sensitive resistance film whose resistance value changes in accordance with the mechanical strain deformation. The resistance film excluding the strain-sensitive resistance film out of the resistance films is a low strain-sensitive resistance film. The resistance film forms a Wheatstone bridge circuit on the same surface of the substrate.SELECTED DRAWING: Figure 1

Description

The present invention relates to a strain resistance element having a built-in bridge circuit and a method for manufacturing the same.

As a technique for measuring strain generated in an object, a strain resistance element or strain gauge having a strain-sensitive resistance film that converts strain deformation into an electric signal (the resistance value changes according to the amount of strain) is mounted or attached to the target object. At the same time, it is generally known that a Wheatstone bridge circuit is formed by the strain resistance element and a plurality of resistance elements or resistance films, and strain measurement is performed using this bridge circuit.
Further, as an element for detecting strain deformation used in such a measurement method, a strain gauge X as shown in FIG. 10 is known (see Patent Document 1).

The strain gauge X is attached on a gauge base 101 in which the grid pattern portion 102, the gauge tab pattern portion 103, and the connection pattern portion 105 are flexible.
In order to convert the amount of mechanical strain on the surface of the object to be measured (machine, structure, etc.) into an amount of electricity such as resistance and voltage for detection, the gauge lead 104 is connected to the measurement circuit and the gauge base. The 101 is attached to the surface of the object to be measured.
In order to accurately detect a small change in resistance value due to strain deformation, the strain gauge shown in FIG. 10 or the like is a Wheatstone bridge circuit Y (hereinafter referred to as a Wheatstone bridge circuit) that converts a resistance change into a voltage change as shown in FIG. It is connected to a bridge circuit (may be abbreviated as a bridge circuit) (see Patent Document 2).

Japanese Patent No. 661348 Japanese Patent No. 30153333

By the way, as shown in FIG. 11, in the Wheatstone bridge circuit Y, in addition to the strain gauge X as shown in the element for detecting strain (FIG. 10), that is, the strain-sensitive resistance element 201, three fixed resistors and the like are used. These resistance elements 205 to 207 are required, but these resistance elements 205 to 207 are connected away from the position where they are distorted and deformed so as not to be affected by the strain deformation. When the resistance values of the resistance elements 205 to 207 change due to the influence of strain deformation, the resistance value balance of the Wheatstone bridge circuit Y is lost. Since the measurement circuit detects the amount of strain by changing the output voltage of the Wheatstone bridge circuit, if the output voltage changes due to changes in the resistance values of the resistance elements 205 to 207 other than the strain-sensitive resistance element 201, the sensitivity of strain detection becomes The accuracy will decrease.
Therefore, the application of the strain gauge X shown in Patent Document 1 to the Wheatstone bridge circuit Y shown in Patent Document 2, which has been generally used in the past, has a problem that the circuit area as a whole becomes large.
Further, the strain gauge X of the prior art needs to be attached to the surface of the object to be measured by an adhesive or the like, and has a problem that it is not suitable for mounting using an automatic machine.

An object of the present invention is to provide a strain resistance element having a built-in bridge circuit and a method for manufacturing the same, which has a monolithic configuration in which a bridge circuit is realized by one element.

According to one aspect of the present invention, a substrate, an electrode formed on the substrate, and a resistance film electrically connected to the electrode are provided, and at least one of the resistance films is mechanically strained and deformed. It is a strain-sensitive resistance film whose resistance value changes according to the above, and among the resistance films, the resistance film excluding the strain-sensitive resistance film is a low-strain-sensitive resistance film, and the resistance film is a Wheatstone on the same surface of the substrate. Provided is a strain resistance element having a built-in bridge circuit, which is a resistance film forming a bridge circuit.
The resistance values of the strain-sensitive resistance film and the low strain-sensitive resistance film are about the same. More preferably, the TCR will be about the same.

The low strain resistance film is preferably made of a cermet resistance material having a structure in which a metallic phase exhibiting metallic behavior and a semiconductor phase exhibiting semiconductor-like behavior are mixed.
The low strain resistance film preferably contains chromium silicon crystals and amorphous silicon nitride or amorphous silicon oxide.

According to another aspect of the present invention, it is a method of manufacturing a strain resistance element with a built-in bridge circuit, which comprises a step of forming a resistance film for forming a Wheatstone bridge circuit on the same surface of the substrate, and has a low feeling on one surface of the substrate. It has a step of forming a strain resistance film and performing a first heat treatment, and a step of forming a strain-sensitive resistance film on one surface of the substrate and performing a second heat treatment at a temperature lower than that of the first heat treatment. A method for manufacturing a strain resistance element having a built-in bridge circuit is provided.

The low strain resistance film is composed of a chromium silicon crystal and a cermet resistance material containing amorphous silicon nitride or amorphous silicon oxide, and the temperature of the first heat treatment is the crystal network of the chromium silicon. It is preferably in the temperature range where the formation of the amorphous substance begins.

According to the present invention, it is possible to provide a strain resistance element having a built-in bridge circuit and a method for manufacturing the same, which has a monolithic configuration in which the bridge circuit is realized by one element.

It is a top view of the strain resistance element with a built-in bridge circuit according to 1st Embodiment of this invention. It is a perspective view of the distortion resistance element with a built-in bridge circuit of FIG. It is a flowchart which shows the manufacturing process of the strain resistance element with a built-in bridge circuit which concerns on this invention. It is a perspective view which shows the state after performing each process of FIG. It is a perspective view which shows the state after performing each process of FIG. It is a perspective view which shows the state after performing each process of FIG. It is a perspective view which shows the state after performing each process of FIG. It is a TEM image after the heat treatment of the cermet resistance material. It is a structure photograph after heat treatment. FIG. 6 is an enlarged photograph of FIG. It is a perspective view of the strain resistance element with a built-in bridge circuit according to the 2nd Embodiment of this invention, and is the figure which shows the modification of FIG. It is a perspective view of the strain resistance element with a built-in bridge circuit according to the 3rd Embodiment of this invention, and is the figure which shows the modification of FIGS. 1 and 7. It is a figure of the strain resistance element with a built-in bridge circuit according to 4th Embodiment, and is the figure which shows the modification of FIGS. 1, 7, and 8. 9 (a) is a view seen from the front surface, and FIG. 9 (b) is a view seen from the back surface. It is a top view of the strain gauge disclosed in Patent Document 1. It is a circuit diagram of the Wheatstone bridge circuit disclosed in Patent Document 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Throughout the specification, the same elements are designated by the same reference numerals.
In the present specification, the states after the film formation by sputtering or the like and before the pattern is formed are referred to as "low strain-sensitive resistance layer", "strain-sensitive resistance layer", and "surface electrode layer".
Further, the state in which the pattern is formed by photolithography or the like is referred to as "low strain-sensitive resistance film", "distortion-sensitive resistance film", and "surface electrode".

(Outline of the invention)
In the present invention, in order to meet the demands of miniaturization and low profile for high-density mounting, one element such as a chip-shaped strain resistance element is referred to as a Wheatstone bridge circuit (hereinafter referred to as a bridge circuit). ) Was conceived.
Since the strain-sensitive resistance film detects the strain deformation of the object to be measured by changing the resistance value according to the mechanical strain deformation, it is necessary to transmit the strain deformation of the object to be measured to the strain-sensitive resistance film. Therefore, when the strain-sensitive resistance film and the resistance film constituting the other bridge circuit are formed on the same substrate (chip shape) and monolithic, the resistance film other than the strain-sensitive resistance film is also strain-deformed. Become.

Therefore, we found a resistance element (low-strain resistance film) that is not easily affected by the strain of the object to be measured even if it is formed on the same substrate as the strain-resistant element (strain-sensitive resistance film). I came up with the idea of using a resistor film.
More specifically, in the present invention, the resistance film constituting the bridge circuit together with the strain-sensitive resistance film changes the resistance value due to the deformation of the base material (the substrate, the circuit board on which the substrate is mounted, etc.) and the reciprocity of the resistance film. It is formed by a low-sensitivity strain resistance film that cancels out due to the resistance value change behavior.
The low strain resistance film is a resistance film containing a metal component (metal phase) and a semiconductor component (semiconductor phase). In particular, it is formed of chromium silicon crystals (metal phase) and irregular (amorphous) silicon nitride or silicon oxide.

The crystalline metal phase (chromium silicon) and the amorphous semiconductor phase (silicon nitride, silicon oxide) show the opposite resistance change behavior to strain deformation. Therefore, the change in the resistance value due to the mechanical deformation is canceled inside the resistance film, so that the resistance film functions as a low strain resistance film.

By using the low strain-sensitive resistance film of the present invention, even if the strain-sensitive resistance film and the resistance film (low-sensitivity strain resistance film) constituting the other bridge circuit are formed on the same substrate, the object to be measured accurately. It is possible to detect distortion.
This makes it possible to provide a distortion resistance element having a built-in monolithic bridge circuit in which a bridge circuit is configured by one element.
Therefore, it is possible to provide a monolithic chip-shaped strain resistance element, which contributes to miniaturization and low profile due to high-density mounting.

(First Embodiment)
FIG. 1 is a plan view of a strain resistance element A with a built-in bridge circuit according to the first embodiment of the present invention. FIG. 2 is a perspective view of the strain resistance element A with a built-in bridge circuit shown in FIG. In the strain resistance element A with a built-in bridge circuit, a bridge circuit is formed on one surface side of the substrate. Then, the strain resistance element A with a built-in bridge circuit is mounted so that the other surface side of the substrate is brought into close contact with one surface of a measurement object such as a glass epoxy board, as in the case of a normal chip-shaped electronic component. For example, in the manufacture of electronic circuit boards, in order to improve production efficiency, multiple product boards may be arranged on a large sheet board to produce a large number of boards at the same time. The stress may adversely affect the joining of parts mounted on the board. Therefore, by mounting the strain resistance element A with a built-in bridge circuit of the present invention on the substrate in the same manner as the mounted component, the mechanical stress on the substrate can be measured as the amount of strain, which is used for verification of the division conditions. Can be done.
Hereinafter, each component will be described with reference to FIGS. 1 and 2. Further, in the following, the arrows indicate the distortion deformation direction. In FIGS. 1 and 2, the protective film (see FIGS. 4C to 4D) is not shown.

1) Board The board 1 forming the bridge circuit of the strain resistance element A with a built-in bridge circuit has a rectangular parallelepiped shape in a plan view. The shape of the substrate 1 plane may be either rectangular or square, but when the strain deformation direction of the object to be measured is unknown, the shape of the substrate 1 plane is changed so that the strain deformation direction does not become the short side direction. It is preferable to make it square.
The material of the substrate 1 is a ceramic substrate or a hard substrate having an insulating treatment on the metal surface (by forming an insulating film on the substrate surface or the like). As the ceramic substrate, for example, a ceramic substrate containing alumina or zirconia as a main component can be used.
A soft material such as resin is used as the material of the substrate 1 in order to easily transmit the strain deformation generated in the object for which the strain is measured by being brought into close contact with the back surface of the substrate 1 to the strain-sensitive resistance film formed on the surface of the substrate 1. A material coated on the surface of the substrate may be used.

2) Front surface electrode / back surface electrode A strain resistance element A with a built-in bridge circuit is formed on one surface (front surface) of the substrate 1. On one surface of the substrate 1, four surface electrodes 7a to 7d made of a substantially rectangular metal film (the material of the metal film is Cu, Ag, Au, etc.) electrically connected to the resistance film are formed.
Backside electrodes 9a to 9d for mounting on an object (mounting board or the like) for measuring strain are formed on the other surface (back surface) of the substrate 1. The front surface electrodes 7a to 7d and the back surface electrodes 9a to 9d are formed by forming a metal film (Cu, Ag, Au, etc.) by sputtering or vapor deposition. Depending on the material of the electrode, it may be formed by screen printing.

Further, the substrate 1 is formed with end face electrodes 10a to 10d connecting the front surface electrodes 7a to 7d and the back surface electrodes 9a to 9d. The end face electrodes 10a to 10d can be formed by a sputtering method targeting a NiCr-based metal material.
The front surface electrode, the back surface electrode, and the end surface electrode may have a plating film 11 (11a to 11d) made of Ni and Sn formed on the surface thereof. The plating film 11 can be used to improve the solder-bonded state with the mounting substrate or the like.

3) Distortion resistance film ( _RST )
The strain-sensitive resistance film 3a is a resistance film whose resistance value changes according to the mechanical strain deformation of the object to be measured. A film can be formed on the substrate 1 by sputtering or vapor deposition.
The material of the strain-sensitive resistance film 3a is appropriately selected according to the required characteristics. For example, a thin film resistor made of CuNi-based alloy, NiCr-based alloy, Cr-based alloy, CrN-based alloy, CrAlN-based alloy, or a semiconductor film made of silicon or the like can be used.

When a low-sensitivity strain resistance element is required, the strain-sensitive resistance film 3a uses a CuNi-based alloy or a NiCr-based alloy (gauge ratio is 1.5 to 3.0). The metal resistance material expands (shrinks) when an external tensile force (compressive force) is applied, and its resistivity increases (decreases). The gauge ratio is a coefficient representing the sensitivity of the strain gauge, and a general metal resistance film has a gauge ratio of about 2.
If a highly sensitive strain resistance element is required, use Cr-based alloys, CrN-based alloys, CrAlN-based alloys (gauge ratio of 5.0 to 20.0), and semiconductor films (gauge ratio of about ± 100). Just choose.

The strain-sensitive resistance film 3a has a meandering pattern in which the length in one direction, which is the strain direction (direction of strain deformation to be measured) D, becomes long. The meandering pattern is arranged so that the longitudinal direction is parallel to the strain deformation to be detected (the same direction as the strain direction D) of the object to be measured. This improves the detection sensitivity of strain deformation. Further, by increasing the total length of the strain-sensitive resistance film 3a, it is possible to increase the change in the resistance value per unit occupied area of the strain-sensitive resistance film 3a on the substrate 1.

4) Low-sensitivity strain resistance film (R ₁ to R ₃ )
The low-sensitivity strain resistance films (R ₁ to R ₃ ) 5a to 5c are characterized by having a high resistivity (resistivity range of CrSi—N: 1 mΩcm or more).
The low strain resistance films (R ₁ to R ₃ ) 5a to 5c are cermet resistance materials having a structure in which a crystalline metal phase exhibiting metallic behavior and an amorphous semiconductor phase exhibiting semiconductor-like behavior are mixed. It is a resistance film made of. The cermet resistance material is formed, for example, mainly composed of an oxide of chromium silicon or a nitride of chromium silicon. The cermet resistance material is, for example, a thin film resistance formed by sputtering with a mixed gas of argon, which is an inert gas, and nitrogen or oxygen, with the target being a CrSi alloy.
These manufacturing methods will be described later with reference to FIGS. 3 and 4.

5 and 6 are TEM images of the cross section of the cermet resistor material after the heat treatment. FIG. 5 is a microstructure photograph after heat treatment, and FIG. 6 is a partially enlarged photograph of FIG.
As shown in FIGS. 5 and 6, the low strain resistance films (R ₁ to R ₃ ) 5a to 5c have a black portion and a white portion mixed together. The black part is a crystal of chromium silicon. The white part is an irregular (amorphous) SiN (semiconductor phase).
The low strain resistance film is a film in which a metal phase and a semiconductor phase are mixed. The change in resistance value due to mechanical strain deformation is canceled by the crystalline metal phase and the amorphous semiconductor phase, so that the low strain resistance film has low strain resistance. Functions as a membrane. Therefore, when the resistivity is low = the metal phase is dominant, it does not function as a low strain resistance film. High resistivity = The mixture of metal phase and semiconductor phase causes the resistance film to function as a low-sensitivity resistance film.
The low strain resistance film may contain a metal element as long as it is a resistance film containing an oxide of chromium silicon or a nitride of chromium silicon as a main component.

The low strain resistance film has a meandering pattern, and is arranged so that the longitudinal direction of the meandering pattern is perpendicular to the direction of strain deformation (strain direction D) to be detected of the object to be measured. ..
The reason is that the distortion detection accuracy is improved by making the longitudinal direction of the meandering pattern of the strain-sensitive resistance film horizontal to the strain deformation to be detected of the object to be measured. When strain deformation occurs on the substrate, the substrate also deforms in the direction perpendicular to the direction D of strain deformation (when the strain deformation is tension, the vertical direction shrinks, and when the deformation is compression, the vertical direction expands). However, the amount of deformation in the direction perpendicular to the direction D of strain deformation of the substrate is much less affected by the strain deformation than the amount of deformation in the strain direction D. That is, by arranging the low-sensitivity strain resistance film in the longitudinal direction of the pattern perpendicular to the strain direction D, the influence of strain deformation can be reduced and the detection accuracy can be further improved.
Further, since the strain-sensitive resistance film ( _RST ) 3 and the low strain-sensitive resistance films (R ₁ to R ₃ ) 5a to 5c form a bridge circuit, their resistance values are formed to be substantially the same. It is preferable to provide a resistance value adjusting region for forming a trimming groove by a laser in each resistance film so that the resistance value can be adjusted to be substantially the same.

<Manufacturing method of the present invention>
The strain resistance element with a built-in bridge circuit according to the present invention can be manufactured by the following steps.

FIG. 3 is a flowchart showing a manufacturing process of the strain resistance element A with a built-in bridge circuit according to the present invention. FIG. 4 is a perspective view showing a state after each step is performed.
In order to start the manufacturing process (STRAT), first, in step S1, a large-sized substrate Z made of alumina, zirconia, or the like for taking a large number of pieces is prepared.
In step S2, grooves L1, L2, ... For substrate division are formed (FIG. 4A (a)).
In step S3, the low strain resistance layer 5 is formed on the substrate 1 (FIG. 4A (b)). The low strain resistance layer 5 is formed of a cermet resistance material made of a thin film resistance material (CrSi—O, CrSi—N, etc.) having a small gauge ratio by sputtering. The one having the higher heat treatment temperature is formed first, but depending on the heat treatment temperature, either the low strain-sensitive resistance layer 5 or the strain-sensitive resistance layer 3 may be formed first.

In step S4, low strain resistance films (R ₁ to R ₃ ) 5a to 5c are formed by photolithography (FIG. 4A (c)).
In step S5, the first heat treatment is performed for adjusting the gauge ratio and TCR of the low-sensitivity strain resistance films (R ₁ to R ₃ ) 5a to 5c (when the second heat treatment can be performed collectively, the first heat treatment is performed. The heat treatment may be omitted).
In step S6, a strain-sensitive resistance layer made of a material (Cr, CrN, NiCr, etc.) having a large gauge ratio by sputtering or vapor deposition on the substrate 1 on which the low strain resistance films (R ₁ to R ₃ ) 5a to 5c are formed. Form 3. Next, in step S7, the electrode layer 7 made of an electrode material (Cu or the like) is formed by superimposing it on the strain-sensitive resistance layer 3 (FIG. 4B (d)). In FIG. 4B (d), the strain-sensitive resistance layer 3 is not exposed on the surface.

In steps S8 and S9, the electrodes 7a to 7d and the strain-sensitive resistance film ( _RST ) 3a are formed by photolithography (FIG. 4B (e)).
In step S10, a second heat treatment is performed to adjust the TCR of the strain-sensitive resistance film ( _RST ) 3 (if TCR adjustment or the like is not required, this heat treatment may be omitted).
The second heat treatment for forming the strain-sensitive resistance film ( _RST ) 3 is performed at a lower temperature than the first heat treatment for forming the low strain-sensitive resistance films (R ₁ to R ₃ ) 5a to 5c. The temperature range of the heat treatment is 600 to 800 ° C for the first heat treatment (temperature range in which chromium silicon crystals begin to form a network), 200 to 500 ° C for the second heat treatment, and preferably about 300 ° C (depending on the material). Is.

Since the low strain resistance films (R ₁ to R ₃ ) 5a to 5c and the strain sensitive resistance films ( _RST ) 3 form a bridge circuit, they are designed so that the resistance values are the same. More preferably, the low strain resistance films (R ₁ to R ₃ ) 5a to 5c and the strain sensitive resistance films ( _RST ) 3 are designed so that both the resistance value and the TCR are equal.

In step S11, for example, a metal mask is brought into close contact with the back surface of the substrate 1 (the opposite surface on which the resistance film or the like is formed), and the back surface electrodes 9a to 9d are formed by sputtering. The formation of the back surface electrode may be omitted depending on the mounting method (FIG. 4B (f)).
In step S12, the surface electrodes 7a to 7d are exposed, and an epoxy resin is printed so as to cover the low strain resistance films (R ₁ to R ₃ ) 5a to 5c and the strain resistance films ( _RST ) 3. , A protective film 61 is formed (FIG. 4C (g)).
In step S13, the substrate 1 is divided into strip-shaped substrates 1a by dicing, breaking, or the like (FIG. 4C (h)).

In step S14, a NiCr-based material is sputtered onto the end face of the strip-shaped substrate 1a to form end face electrodes 10a to 10d (FIG. 4D (i)). This step may be omitted depending on the mounting method.
In step S15, the substrate 1a on the strip is divided into individual pieces, that is, chips (individualized substrate 1b) (FIG. 4D (j)).
In step S16, the plating film 11 (11a to 11d) is formed on the front surface electrodes 7a to 7d, the end face electrodes 10a to 10d, and the back surface electrodes 9a to 9d (FIG. 4D (k)).
Through the above steps, the strain resistance element with a built-in bridge circuit of the present invention can be manufactured.
The above steps are exemplary, and the manufacturing method is not limited to these steps.

(Second embodiment)
Next, a second embodiment of the present invention will be described. FIG. 7 is a perspective view of the strain resistance element with a built-in bridge circuit according to the second embodiment, and is a diagram showing a modified example of FIG. 1. The protective film is omitted. In FIG. 3, the protective film (see FIGS. 4C to 4D) is not shown.

As shown in FIG. 7, in the strain resistance element B with a built-in bridge circuit according to the present embodiment, the strain-sensitive resistance film ( _RST ) 3 which is a resistance film and the low strain-sensitive resistance film (R ₁ to R ₃ ) 5a to The pattern is designed so that the resistance value is substantially the same as that of 5c.
However, in reality, the resistance value may vary.
Therefore, in the present embodiment, in the strain resistance element B with a built-in bridge circuit, the resistance value of the resistance film can be adjusted after the pattern is formed.
More specifically, it is preferable to form a resistance value adjusting region in advance in the pattern of the resistance film formed on the surface of the substrate 1 of the strain resistance element B with a built-in bridge circuit.

The resistance value adjusting region is a pattern of a resistance film formed in advance on the substrate 1. The pattern may be, for example, bulging patterns 21, 23, 25, 27 bulging from the line width of the meandering pattern. The bulging pattern is a pattern in which a part of the meandering pattern in the longitudinal direction is widened. Further, the coarse adjustment pattern 29 may be used in which the bulging portion is removed in a substantially rectangular shape. It is arbitrarily selected from these patterns and formed on the substrate 1.
Further, depending on the required resistance value, for example, when a high resistance value is required, the pattern of the resistance film needs to be lengthened (routed), and the occupied area of the resistance film needs to be widened. Therefore, the region where the resistance film is formed may be widened toward the central region of the substrate 1, or the resistance film may be formed in the central region.
According to the present embodiment, even when an elongated meandering pattern is formed in order to obtain a high resistance value, the resistance value can be easily adjusted by forming a wide bulging pattern in advance. Become.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 8 is a perspective view of the strain resistance element with a built-in bridge circuit according to the third embodiment, and is a diagram showing a modified example of FIGS. 1 and 7. The protective film is omitted.

As shown in FIG. 8, in the strain resistance element C with a built-in bridge circuit according to the present embodiment, the strain-sensitive resistance film ( _RST ) ₃ which is a resistance film and the low strain-sensitive resistance film ( _R1 to R3) 35a to The pattern is designed so that the resistance value is substantially the same as that of 35c.
Since the low strain-sensitive resistance films (R ₁ to R ₃ ) 35a to 35c are films in which a metal phase and a semiconductor phase are mixed, the resistivity is higher than that of the strain-sensitive resistance film _RST 3.

Low strain resistance film (R _ST ) _{3, Low strain resistance film (R 1 to R 3 ) 35a} to 35c May be a simple linear pattern instead of a meandering pattern.
In this way, since the pattern design is simple, defects due to pattern abnormalities can be reduced, the manufacturing process can be simplified, and strain-sensitive resistance films ( _RST ) ₃ , low strain-sensitive resistance films ( _R1 to R3) can be reduced. Since 35a to 35c can be visually distinguished from each other, there is an advantage that the mounting direction can be easily confirmed.

(Fourth Embodiment)
Next, a fourth embodiment of the present invention will be described. FIG. 9 is a perspective view of the strain resistance element with a built-in bridge circuit according to the fourth embodiment, and is a diagram showing modified examples of FIGS. 1, 7, and 8. The protective film is omitted. 9 (a) is a view seen from the front surface, and FIG. 9 (b) is a view seen from the back surface.

As shown in FIG. 9A, on the substrate 1 surface 71, four surface electrodes 7a to 7d may be unevenly distributed on one side of a square or the like depending on the wiring pattern of the circuit board to be mounted. ..
In such a case, as shown in FIGS. 9A and 9B, a resistance film in which the strain-sensitive resistance film ( _RST ) 43 is routed along each side of the substrate surface on the surface 71 of the substrate 1. The internal pattern 41a in which the low strain resistance films (R ₁ to R ₃ ) 41a to 41c are formed in the internal region near the center of the substrate surface 71, that is, inside the pattern of the strain resistance film ( _RST ) 43. It may be set to ~ 41c.
With such internal patterns 41a to 41c, a wide area for forming the strain-sensitive resistance film ( _RST ) 43 can be secured, and when combined with the fixing metal film 51, strong adhesion is achieved, and stable strain detection and stable strain detection can be performed. It has the advantage of improved durability.
Further, as shown in FIG. 9B, on the back surface 72 of the substrate 1, the back surface electrodes 51a to 51d are formed at positions corresponding to the front surface electrodes 7e to 7h. Further, on the back surface 72, apart from the back surface electrodes 51a to 51d, a fixing metal film 51 for soldering is formed by, for example, plating, spattering, coating, or the like.
As described above, as described in the present embodiment, the positions and shapes of the front surface electrodes and the back surface electrodes can be changed according to the shape and arrangement of the wiring of the circuit board of the mounting destination. In particular, by arranging the front surface electrodes and the back surface electrodes unevenly in the vicinity of the edges of the substrate, the low strain resistance films (R ₁ to R ₃ ) 41a to 41c can be provided in the center of the surface of the substrate 1. , It becomes possible to secure a wide area for forming the strain-sensitive resistance film ( _RST ) 43.

In the above embodiment, the configuration and the like shown in the illustration are not limited to these, and can be appropriately changed within the range in which the effect of the present invention is exhibited. In addition, it can be appropriately modified and implemented as long as it does not deviate from the scope of the object of the present invention.
In addition, each component of the present invention can be arbitrarily selected, and an invention having the selected configuration is also included in the present invention.

The present invention can be used for a strain resistance element having a built-in bridge circuit.

A, B, C Strain resistance element with built-in bridge circuit D Direction of strain deformation X Strain cage Z Large board 1 Board 3a Strain-sensitive resistance film ( _RST )
5a-5c Low-sensitivity strain resistance film (R ₁ to R ₃ )
7a to 7d Front surface electrodes 9a to 9d Back surface electrodes 10a to 10d End face electrodes 11 Plating layer (coating)

Claims (5)

With the board
The electrodes formed on the substrate and
It has a resistance film that is electrically connected to the electrode.
At least one of the resistance films is a strain-sensitive resistance film whose resistance value changes according to mechanical strain deformation.
Of the resistance films, the resistance films other than the strain-sensitive resistance film are low strain-sensitive resistance films.
A strain resistance element with a built-in bridge circuit, wherein the resistance film is a resistance film that forms a Wheatstone bridge circuit on the same surface of the substrate. The strain resistance element with a built-in bridge circuit according to claim 1, wherein the low strain resistance film is made of a cermet resistance material having a structure in which a metal phase exhibiting metallic behavior and a semiconductor phase exhibiting semiconductor behavior are mixed. The strain resistance element with a built-in bridge circuit according to claim 1 or 2, wherein the low strain resistance film contains chromium silicon crystals and amorphous silicon nitride or amorphous silicon oxide. A method for manufacturing a strain resistance element with a built-in bridge circuit, which comprises a step of forming a resistance film for forming a Wheatstone bridge circuit on the same surface of a substrate.
The process of forming a low strain resistance film on one surface of the substrate and performing the first heat treatment,
A method for manufacturing a strain resistance element with a built-in bridge circuit, which comprises a step of forming a strain-sensitive resistance film on one surface of the substrate and performing a second heat treatment at a temperature lower than that of the first heat treatment. The low strain resistance film is composed of chromium silicon crystals and a cermet resistance material containing amorphous silicon nitride or amorphous silicon oxide.
The method for manufacturing a strain resistance element with a built-in bridge circuit according to claim 4, wherein the temperature of the first heat treatment is in a temperature range in which the crystal network of chromium silicon begins to be formed.

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