JPS58161803A - strain sensor - Google Patents

Abstract

PURPOSE:To obtain high reliability, by forming an insulating film on a beam body provided with thin parts, connecting resistor bodies having specified composition of three components Ni, Cr, and Si at the corresponding position on said film so as to form a bridge, thereby forming conductive layers. CONSTITUTION:The insulating film 9 is formed on a beam body 2 with the thin parts 4. The resistor bodies 10 made of a thin film are laminated and formed at the positions corresponding to a thin parts 4 on said film 9. The conducting layers 11, wherein the resistor bodies 10 are connected in the bridge form, are laminated and formed. The resistor body 10 is constituted by using the material having the composition surrounded by a quadrilateral figure formed by connecting a point w (Ni is 50, Cr is 50, and Si is 0), a point x (Ni is 90, Cr is 0, and Si is 10), a point y (Ni is 77, Cr is 0, and Si is 23), and a point z (Ni is 50, Cr is 40, and Si is 10) (numerals in parentheses are weight %), in a triangle chart of the three components Ni, Cr, and Si.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strain sensor suitable for use in load cell scales and the like.

A strain sensor used in a load cell weighing device forms a beam having four thin parts, and bridge-connects the beam with a strain gauge attached to each thin part. Since such devices are bulky and unstable, it has been proposed to utilize thin film technology to connect thin film resistors and their connections. In this case, Njcr alloy is used as the thin film resistor material. In this case, a low temperature coefficient of resistance is required, but since the temperature coefficient of resistance is controlled by the composition of N1-Cr and the amount of oxygen, it has the disadvantage that it is difficult to control oxidation. . Also,
Depending on the composition of Nt-Cr, there is a problem that the change over time is large and stability is lacking.

The present invention has a low temperature coefficient of resistance and is easy to control.
The purpose of the present invention is to obtain a strain sensor equipped with a resistor that exhibits a stable state.

In the present invention, an insulating film is formed on the surface of a beam body, and a resistor and a conductive layer are laminated thereon using thin film technology. By setting the composition distribution of It is.

An embodiment of the present invention will be described based on the drawings.

First, a metal elastic body, for example 80863G (JI8)
Stainless steel such as A 221g (JIS) or high strength aluminum such as
), and two circular holes (3) communicating with each other are provided in the beam body (2) to form a thin wall ms (4).
form. One end of the beam body (2) is fixed* (6), and the other end is a load receiving portion (6). The fixing part (5) is formed with a mounting hole (7) into which a mounting bolt is inserted, and the load receiver IIS (6) is formed with a locking hole (8) into which a lower barrel fitting or a load receiver is attached. )
is formed.

Therefore, the surface (1) is covered with an insulating film (9).
is formed. This insulating film (9) is made of an insulating resin or an inorganic compound, such as polyimide resin. In this case, a polyimide resin with a viscosity of 100GCP is applied with a spinner of 160Or, p, m,
It is formed by heating and curing it to a uniform thickness.

Next, using the resistor material as a target, sputtering is performed on the insulating film (9) to form a thin film resistor. The material of this resistor αQ is shown in the three-component triangular diagram shown in figure jlK3 at point W (N45G, C de50.8
40) (but exceeds BtFiO), X point (Ns
eo, cro, 8i 10), Y point (N<77,
Cr018423), 2 points (N's50, Cr40.
auto) (However, the unit of numbers in parentheses is wt%)
It is within the range surrounded by the rectangle connecting the . The conditions at this time are: power source RFIKW degree of vacuum 4×1G TORR Af pressure 4×10 toRR film thickness 500 A.

A film with a thickness of 1 μm is placed on the resistor (to) formed in this way.
A film of gold is formed to form a conductive layer α.

By selectively etching the layers of the conductive layer αυ and the resistor (to), as shown in Figure 2, leads are formed to connect the four gauge parts (2) and these gauge parts to each other for a bridge connection. A wire portion (2) and a rounded terminal portion Q4 of external wiring are formed.

In addition, among the materials of the above-mentioned resistor (to), F-1Co is included.

MnlMo, W, V, T4. Zs, Zr%H/, T
a, Ni, B, AJ.

It is permissible to contain less than 5 wt% of elements such as Mg%Ga, SNS, PBS, CSP, etc. alone or in combination. This means that it is actually difficult to add any of the elements Ni, C, or 84 as a single element, and that it is essential to prevent the mixing of other metals within an industrially common sense range. This is acceptable in range 1 where the performance does not change. In addition, regarding M% etc., 0.01 to 0.1 is the ninth factor to improve workability.
It is desirable to actively add wt% lift.

The resistor (2) constructed in this way has a low temperature coefficient of resistance, with little change in resistance value due to temperature changes, and its change over time is extremely stable and in good condition as shown in Figure 4. show.

In the present invention, as mentioned above, the resistor formed on the insulating film of the beam body is made of a Ni-Cr-84 alloy, and its composition range is also the W point (Nf50, Cde50,
fii O), X point (NIO1CrO18i 10 )
, Y point (N(77, Cr011023), 2 points (
Ni50, Cr40. Bi 1G) (however, the unit of numbers in parentheses is wt%), so it has a low resistance temperature coefficient, and it is easy to control the temperature coefficient of the PPM overlaying the resistance temperature coefficient. In the case where four resistance change parts of a resistor are formed and bridge-coupled.

Because there is little variation in the temperature coefficient of each part, there is little temperature drift at the zero point, and a product that is stable over temperature can be obtained.
Further, it has the advantage that there is very little change over time and high reliability can be obtained over a long period of time.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Fig. 511 is a partially exaggerated side view, Fig. 2 is a plan view showing the shape of the resistor with a live conductive part, and Fig. 3 is a three-component triangular diagram. Stripe 4 is a graph showing the change in resistance value over time. 2... Beam body, 4... Thin wall part, 9... Insulating film,
10...Resistor, 11...1 mouth to conductive layer fog. Figure 7

Claims (1)

[Claims] 1. An insulating film is formed on a beam body having a thin wall portion, and thin film resistors are stacked on the insulating film at positions corresponding to the thin wall portions, and these resistors form a bridge. In the structure in which conductive layers connected to each other are laminated, the resistor is made of Ni-Cr-at. Point W in the ternary triangular diagram (N450.Cr 5G%840
), X point (Ni90, Cry, 8jlG), Y point (
Ns 7? , Cry, Bi23), -2 points (Ni50.
A strain sensor characterized in that the material has a composition within a range surrounded by a rectangle connecting Cr2O, 8410) (71j, and the units of numbers in parentheses are wt%). 2. F-1Co, Mo, Mo, W in the material of the resistor
, V, Ti, Zs, Zr, H/, Ta, Nb, B,
According to claim 1, the elements 1, Mg, Ga, 8s, P6%C%P are allowed to be mixed alone or in combination of two or more without Swt%. Strain sensor.