JPS59128402A - Strain sensor - Google Patents

Abstract

PURPOSE:To obtain a highly accurate strain sensor, by removing a part of a first resistance layer, forming a temperature compensating resistor only by a second resistance layer, thereby enhancing the function of the temperature compensating resistor. CONSTITUTION:A first resistance layer 16, which is to become a strain gage resistor, is formed on an insulating layer 15 on a beam piece 1 made of metal material and the like by sputtering and the like. A part of the layer 16 is removed through a mask by etching and the like. A second resistance layer 17 and a wiring pattern conductive layer 18 are laminated on the layer 16, and a strain sensor is formed. Since there is the removed part in the layer 16, a temperature compensating resistor can be formed only by the layer 17. In comparison with the case where the temperature compensation resistor is formed under the sate the layers 16 and 17 having the different resistance values are laminated, adjustment is made easy, the function of the temperature compensation resistance is enhanced, and the highly accurate strain sensor can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to some sensors that apply thin film technology and are used, for example, as load cell scales.

Technical Background and Problems Generally, in this type of strain sensor, a first resistance layer, a second resistance layer, and a conductive layer are sequentially laminated on an insulating film formed on the surface of a beam body. , a selective etching process is performed to form a strain gauge resistor using the first resistive layer, a multi-temperature compensation resistor is formed using the laminate of the first resistive layer and the second resistive layer, and A serial lead circuit (turn) is formed by a laminate of a first resistance layer, a second resistance layer, and a conductor layer. However, the temperature compensation resistor is a second resistance with a large resistance temperature coefficient. Since it is a laminate of a first resistive layer and a first resistive layer having a small temperature coefficient of resistance, it is difficult to fully exhibit its function as a temperature-compensating resistor.

OBJECTS OF THE INVENTION The object of the present invention is to obtain a highly accurate ton sensor by enhancing the function of a temperature compensation resistor.

SUMMARY OF THE INVENTION The present invention makes it possible to form a resistor with only the second resistive layer by omitting a portion of the first resistive layer when forming the first resistive layer, thereby reducing the temperature coefficient of resistance. big second
Since the temperature compensation resistance is formed only in the resistance layer of be.

Embodiments of the Invention First, an embodiment of the present invention as used in a load cell will be described with reference to the drawings. First, a prismatic beam body (1) is formed from stainless steel material. This beam body (1) has thin deformed portions (4) formed at four locations by two holes (2) and grooves (3) that communicate these holes (2).

Further, a mounting hole (5) for attaching to a fixed part such as a base is formed at one end, and a load receiving hole (6) to which a receiving plate is connected is formed at the other end.

Next, the negative surface of the beam body (1) is the pattern forming surface (
7) is formed flat. A circuit as shown in FIG. 2 is patterned on this pattern forming surface (7) by means described later. First, R1-R4 are strain gauge resistors (8); rz and r3 are bridge-balanced temperature compensation resistors (9), and a bridge circuit is formed by these. Also, Rs.
and Rc is the output voltage temperature compensation resistance (snow resistance).
a*α, which mainly compensates for the temperature characteristics of the Young's modulus of the beam body (1). And Ve and Ve- are input voltage V
6,! at the input terminal (6) to which e is applied. II), V
o and Vo−° are the output terminal α to which the output voltage Vo is applied.
→ is.

Therefore, in order to form the temperature-compensated resistance circuit α→ as shown in FIG. later,
A polyimide resin film that has been degreased and cleaned and whose viscosity has been adjusted to 1000 cp (centipoise) is dropped onto it, and then it is
The coating was applied uniformly by rotating at a rotational speed of 0 Or, p = m, the solvent was evaporated by heating at 100°C for 1 hour, and then the resin was cured by heating at 350°C for 1 hour. An insulating layer αυ made of a polyimide resin film with a thickness of 4 μm is formed.

Next, NiCr5i (Nj 70
, Cr2O, Si10) with a thickness of 0.1μ is formed.Next, a second resistance layer α of Ti with a thickness of 1μ is laminated by vacuum evaporation. moreover,
A conductive layer αe made of C1L having a thickness of 2 μm is laminated thereon.

Then, as shown in FIG. 5, the layers other than the shiba vern portion are photoetched in order from 0rb-+Ti to NiCrSi using respective etchants.

The insulating layer a→ is exposed except for the pattern portion.

Then, as shown in FIG. 6, in a second photoetching process, Cw layered on the strain gauge resistor (8) and the temperature compensation resistor (9) (αη) is etched using the etchant. do. Therefore, the Ti film is exposed in this etched portion. This process allows R
The temperature compensation resistor (9) of s, rz, and r3 is completed.

Furthermore, as shown in FIG.
By etching the Ti stacked on the temperature compensation resistor αυ and Rc, the NiCr5i layer is exposed at the respective portions. This completes pattern formation.

As a result, the strain gauge resistor (8) and the temperature compensation resistor Rc are formed by the first resistance layer α.
The temperature compensation resistor (9) αQ of RB, rz, r3 is formed only by the second resistance layer αη, and the input terminal (6)
The lead circuit pattern α9) including the output terminal 03 and the output terminal 03 is formed by a laminate of a first resistance layer αQ, a second resistance layer αη, and a conductive body layer 4.

When a load is applied to the load receiving hole (6), tensile strain occurs in R1 and R2 of the strain gauge resistor (8), increasing the resistance value, and compressive strain occurs in R3 and R4. The resistance value decreases. As a result, it is well known that multiple output voltages ΔvO are generated according to the following relational expression.

Here, RB is the bridge resistance seen from the input side.

R1=R2=R3=kFR, ΔR1=ΔR2− also ΔR
By designing so that 3=ΔR,=ΔR, ■
Equation Here, the output voltage (sunokun) temperature characteristic when span temperature compensation resistors Rs and Rc are not provided is the beam body (1
) is a stainless steel material, the temperature at 40°C is +0.7% larger than at 0°C, as shown in FIG. 8 in the range of 0°C to 40°C.

In addition, as a span temperature compensation resistor, for example, using Tj of resistance temperature coefficient +3000 ppm 10C, the output voltage V
When the temperature characteristic of o is compensated to be flat, the curvature of the compensated curve becomes upwardly convex by about 0.03% as shown in FIG. It is generally known that as a method of compensating for this curvature, it is possible to flatten the span resistance by inserting Rc having a resistance temperature coefficient of approximately zero in parallel with the span resistance Rs. The state is shown in Fig. 10, where the layer property (■) is when the values of Rs and Rc are optimal, the property (2) is when Rc is too small, and the property (■) is when Rc is too small. This is the case where there is no.

By appropriately selecting Rs and Re in this way, the 10th
A state as shown in the characteristic (■) in the figure can be obtained, and the first resistance layer CL→ and the second resistance layer α force are each NiCr5j
Since the Tj layer and the Tj layer are single layers, setting and adjusting the resistance value thereof is extremely easy and accurate.

Incidentally, in the above embodiment, when forming the first resistance layer αQ, a part of the first resistance layer αQ was cut out in the mask.
In practice, the entire structure may be formed uniformly, and the two parts may be removed by machining.

Effects of the Invention The present invention sequentially forms a first resistance layer, a second resistance layer, and a conductive layer on an insulating film formed on the surface of a beam body as described above, and then selectively etches the resist layer. In a device in which a range gauge resistor, a temperature compensation resistor, and a lead circuit pattern are formed, when forming the first resistor layer, a part thereof is removed by a masking method or a photoetching method. Furthermore, it is easy to form part or all of the temperature compensation resistor using only the second resistance layer, which also makes it easy to set and adjust the value of each temperature compensation resistor. Therefore, it is possible to greatly improve accuracy, and it is also easy to flatten the temperature characteristics of the output voltage by connecting the second resistance layer and the first resistance layer in parallel. It is something.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a perspective view, Fig. 2 is a circuit diagram, Fig. 3 is a plan view when forming each layer, and Fig. 4 is taken along A-A in Fig. 3. FIG. 5 is a plan view when forming the pattern portion; FIG. 6 is a plan view when etching the conductor layer; FIG. 7 is a plan view when etching the second resistor layer; FIG. The figure is a temperature characteristic diagram of the output voltage when no span temperature compensation resistor is provided, Figure 9 is a characteristic diagram when compensation is performed with a span temperature compensation resistor, and Figure 10 is a characteristic diagram showing various compensation states. . 1... Beam body, 8... Strain gauge resistor, 9
~11... Temperature compensation resistor, 14... Temperature compensation resistance circuit, 15... Insulating layer, 16... First resistance layer, 1
7... Second resistance layer, 18... Conductor layer, 19...
・Applicant for lead circuit pattern To Tokyo Electric Co., Ltd. name J Figure 3 u vote l also δ To] 6 Figure 1 collection 77111 1 ○ Figure U7 plate puller ('C)

Claims (1)

[Claims] 1. On the insulating film formed on the surface of the beam body, a first
After successively laminating a resistive layer, a second resistive layer, and a conductive layer, a selective etching process is performed to form a strain gauge resistor on the first resistive layer, and then the first resistive layer and the second resistive layer are laminated. A multi-temperature compensation resistor is formed by a laminate with a resistance layer, and a series lead circuit pattern is formed by a laminate of a first resistance layer, a second resistance layer, and a conductor layer, A part or all of the temperature compensating resistor is formed only in the second resistive layer by omitting a part of the first resistive layer when forming the first resistive layer. Strain sensor. 2. The first layer is placed on the insulating film formed on the surface of the beam body.
After successively laminating a resistive layer, a second resistive layer, and a conductive layer, a selective etching process is performed to form a strain gauge resistor using the first resistive layer, and then the first resistive layer and the second resistive layer are stacked. A multi-temperature compensation resistor is formed in a laminate, and a series lead circuit pattern is formed in a laminate of a first resistance layer, a second resistance layer, and a conductor layer, wherein the first By cutting out a part of the resistive layer when forming the resistive layer, a resistor made of only the second resistive layer is formed, and a resistor made of only this second resistive layer and a resistor made of the first resistive layer are formed. A strain sensor characterized in that a temperature compensation resistance circuit is formed by connecting these in parallel.