JP3229460B2 - Strain gauge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain gauge, and more particularly to a strain gauge having a gauge film made of amorphous.

[0002]

2. Description of the Related Art Generally, a metal resistor strain gauge has a low gauge factor of 2 to 4, but has a small temperature coefficient of resistance (hereinafter, referred to as TCR) and thus has excellent temperature characteristics. For example, advanced (54)
% Cu, 44% Ni, 1% Mn, 0.5% Fe alloy) or karma (73% Ni, 20% Cr, 7% Al + Fe alloy) or the like, the TCR is about 20 × 10 ^−6. /
℃, Nichrome V (80% Ni, 20% Cr alloy)
Is used, the TCR is about 110 × 10 ⁻⁶ / ° C. This is the TCR (1-3) of the material of the semiconductor strain gauge.
(× 10 ⁻³ / ° C.), the TCR is smaller by about one to two digits, and it is understood that the temperature characteristic is superior to that of the semiconductor strain gauge.

Further, when the gauge film is made of an amorphous material, the TCR is further lowered, and in some cases, the gauge film shows a negative value. Here, in order to make the gauge film amorphous, a metalloid (including a semimetal) may be added, or the composition having a eutectic type may be changed to a composition near the eutectic composition. For example, the aforementioned Nichrome V (80% Ni,
(20% Cr alloy) has a eutectic type, so the composition ratio is changed to the vicinity of the eutectic composition, and TC is added by adding a small amount of metalloid.
R becomes as small as −20 × 10 ⁻⁶ / ° C. and shows a negative value.

[0004] However, even if the gauge film is made amorphous as described above, the TCR cannot be completely reduced to zero, so that an error occurs in the measured value due to the influence of the temperature change, and an accurate measurement is performed. There was a problem that a value could not be obtained.

The present invention solves the above-mentioned problems of the prior art. By making the TCR closer to zero, the influence of a temperature change can be reduced as much as possible, thereby increasing the measurement accuracy. It is an object to provide a strain gauge.

[0006]

The present invention to solve the above problems In order to solve the problems] In the strain gauge constituted gauge film amorphous, said gauge layer NiCr alloy
(Ni; 30 to 70%, Cr; 30 to 70%, Si, G
e and other metalloids; not more than 30%)
Around the crystallization start temperature (in the air; 360-370 ° C, Ar
(Medium: 390 to 400 ° C.) .

[0007]

According to the present invention, by employing the above-described means, the TCR of the gauge film can be made nearly zero. Therefore, the influence of the temperature change is almost eliminated, and the measurement accuracy is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in the drawings will be described below. 1 to 7 show an embodiment of a strain gauge according to the present invention. A gauge film 3 made of amorphous is formed on a metal diaphragm 1 by a thin film forming method such as vacuum deposition and sputtering. The strain gauge 6
It is what it was.

That is, first, as shown in FIG.
_{In addition} to forming an insulating film 2 made of 2 with an appropriate thickness,
As shown in FIG. 2, a gauge film 3 made of amorphous is formed on the upper surface of the insulating film 2 by sputtering or the like.

Here, in order to make the gauge film 3 amorphous, as described above, a metalloid (including a semimetal) is added, and in the case of a eutectic type, the composition is changed to a vicinity of the eutectic. In this case, a NiCr alloy (N
i; 30 to 70%; Cr; 30 to 70%; metalloids such as Si and Ge; 30% or less).

Then, as shown in FIG. 3, the upper surface of the gauge film 3 is masked with an electrode pattern using a metal mask, and the electrode film 4 having a desired pattern is formed by sputtering or the like.
As shown in FIG. 4, a resist 5 is applied to the entire surface of the gauge film 3 to form the gauge film 3 and the electrode film 4.
Then, as shown in FIG. 5, a portion of the resist 5 to be etched is removed to form an appropriate resist pattern.

Then, as shown in FIG. 6, the gauge film 3 is etched by wet etching to form a desired gauge pattern, and thereafter, the resist 5 is removed as shown in FIG. Is formed.

Thereafter, the strain gauge 6 according to this embodiment is formed by heating the NiCr alloy constituting the gauge film 3 to a crystallization start temperature and performing a heat treatment. Here, in the atmosphere, 360 ° C. to 3 ° C.
Heat treatment is performed within the range of 70 ° C., and 390 ° C. in Ar
Heat treatment is performed within the range of 400 ° C.

FIG. 8 shows a strain gauge 6 according to this embodiment.
The heat treatment temperature is indicated in Table analysis of X-ray diffraction shows crystallinity relationship, from this figure, when the heat treatment temperature of 360 ° C. or less in the atmosphere, the peak of the NiCr alloy shows a halo At 380 ° C., a sharp peak began to appear, indicating that crystallization had started.

Similarly, Ar shows a halo at 360.degree. C., indicating that it is in an amorphous state, and a sharp peak starts to appear at 400.degree.
It can be seen that crystallization has started.

FIG. 9 shows the relationship between the heat treatment temperature and the TCR. From this figure, it can be clearly seen that the TCR approaches zero near the crystallization start temperature both in the air and in Ar.

From the above results, it was found that the strain gauge 6 according to this embodiment was set near the crystallization start temperature, that is, at about 3 ° C. in the atmosphere.
60 ° C to 370 ° C, 390 ° C to 40 ° C in Ar
If the heat treatment is performed within the range of 0 ° C., the TCR becomes ± 3 × 10 ^−6.
It can be within ° C.

[0018]

Effects of the Invention The present invention as described above, the gauge film N
iCr alloy (Ni; 30 to 70%, Cr; 30 to 70
%, Metalloids such as Si and Ge; 30% or less).
Around the crystallization onset temperature (in the atmosphere; 360-3
70 ° C. in Ar; 390 to 400 ° C.)
Draws out physical properties that take advantage of the characteristics of amorphous
You can do it. Therefore, the temperature coefficient of resistance (TCR) can be made close to zero.
Therefore, the strain gauge is hardly affected by the temperature change , and a strain gauge having excellent measurement accuracy can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first stage of a method for manufacturing a strain gauge according to the present invention.

FIG. 2 is an explanatory diagram showing a second stage.

FIG. 3 is an explanatory diagram showing a third stage.

FIG. 4 is an explanatory diagram showing a fourth stage.

FIG. 5 is an explanatory diagram showing a fifth stage.

FIG. 6 is an explanatory diagram showing a sixth step.

FIG. 7 is an explanatory diagram showing a seventh stage.

8 is a X-ray diffraction analysis results showing the heat treatment temperature and the crystallinity of the relationship between the strain gage according to the present invention.

FIG. 9 shows the heat treatment temperature and TC of the strain gauge according to the present invention.
It is explanatory drawing which showed the relationship with R.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diaphragm 2 ... Insulating film 3 ... Gauge film 4 ... Electrode film 5 ... Resist 6 ... Strain gauge

Claims (1)

(57) [Claims] 1. A strain gauge having a gauge film made of amorphous, wherein the gauge film is made of a NiCr alloy (Ni;
30-70%, Cr; 30-70%, Si, Ge, etc.
(Taloid; 30% or less)
Near the starting temperature (in the atmosphere; 360-370 ° C., in Ar; 39)
(0 to 400 ° C.) .