KR102256830B1 - Pressure sensor which uses amorphous alloy - Google Patents

Abstract

The present invention relates to a pressure sensor using an amorphous alloy, the pressure sensor using an amorphous alloy according to an embodiment of the present invention, at least a part of the substrate made of amorphous metal; An elastic film disposed on the substrate; And a pressure detection thin film disposed on the elastic film and at least partially made of an amorphous metal, wherein a limit strain of the substrate and the elastic film is greater than or equal to the limit strain of the pressure detection thin film.

Description

Pressure sensor which uses amorphous alloy}

The present invention relates to a pressure sensor using an amorphous alloy.

Unlike a crystalline alloy, an amorphous alloy is a solid material having a structure similar to a liquid phase without a crystal structure due to the irregular arrangement of atoms. The amorphous alloy has excellent mechanical strength because it has no crystallographic anisotropy, and has excellent corrosion resistance due to its uniform structure and composition.

The pressure sensor is used to measure the pressure in a wide range from low to high pressure, especially high precision, such as hydraulic pressure of automobile engines and general industrial pressure measurement. When pressure is applied to a device including a strain gauge, which is a type of pressure sensor, the substrate supporting the strain gauge is deformed, causing the strain gauge to deform together. When the strain gauge is deformed, a length change occurs. At this time, as the resistance value changes, it is converted into an electrical signal, which is operated by the Wheatstone bridge principle.
That is, as disclosed in Korean Patent Publication No. 10-2001-0105084 (Patent Document 1), referring to FIG. 8 to describe the structure of a general strain gauge, a stainless steel diaphragm 10 having a mirror-treated surface on one side thereof, A polyimide 14 deposited on the upper surface of the stainless steel diaphragm 10, a strain gauge 12 having a composition of Cu-Ni and having a predetermined shape pattern formed on the upper surface of the polyimide 14, and the strain gauge 12 ) Extending from and having a predetermined shape and formed on both sides of the electrode contact portion 18 and the protective film 20.
A method of manufacturing the metal thin film strain gauge configured as described above will be described as follows.
First, the polyimide 14 is laminated and deposited on the upper surface of the stainless steel diaphragm 10, and then, a pattern having a composition of Cu-Ni and a predetermined shape is formed, and a strain gauge having electrode contact portions 18 formed on both sides of one end ( 12) is formed by photo etching, and the protective film 20 is formed to complete the assembly.

In general, among the constituent materials of a pressure sensor, stainless steel, aluminum, and Constantan are mainly used for the substrate. However, since these materials have a small elastic strain of about 0.2%, there is a problem that it is impossible to measure a wide range during measurement. In addition, when it exceeds the measurable range, plastic deformation proceeds, which soon reduces the accuracy and sensitivity of the sensor, making it difficult to measure a very small weight.

Unexamined Patent Publication No. 10-2001-0105084 (Publication date 2001.11.28)

An object of the present invention is to provide a pressure sensor having a large limiting strain to provide a pressure sensor having a wide measurement range.

Another object of the present invention is to provide a pressure sensor having excellent durability and corrosion resistance.

A pressure sensor according to an embodiment of the present invention includes a substrate made of at least a part of an amorphous metal; An elastic film disposed on the substrate; And a pressure detection thin film disposed on the elastic film and at least partially made of an amorphous metal, wherein a limit strain of the substrate and the elastic film is greater than or equal to a limit strain of the pressure detection thin film.

The pressure detection thin film may include at least one of Cu, Co, Zr, Ni, and Fe.

The substrate, the elastic film, and the pressure detection thin film may have a strain rate of 1.5 to 2.5% at which elastic strain changes to plastic strain in a stress-strain diagram.

The pressure detection thin film may contain 20 to 70 at% Zr, the balance Cu, and other inevitable impurities with respect to the entire pressure detection thin film, and the thickness of the pressure detection thin film may be 5 μm or less.

The pressure detection thin film may contain 5 to 20 at% of Si, 5 to 20 at% of B, the remainder of Co and other inevitable impurities with respect to the entire pressure detection thin film, and to improve corrosion resistance and amorphous formation ability, the pressure detection thin film At least one of Cr, Fe, and Ni may be included in an amount of 5 at% or less with respect to the whole, and the thickness of the pressure detection thin film may be 10 to 20 μm.

The substrate may be any one of a bending type and a shear type.

The pressure detection thin film and substrate may be manufactured by any one of a rapid solidification method and a sputtering deposition method.

The pressure sensor according to an embodiment of the present invention has excellent elastic strain, durability, and corrosion resistance, and can measure pressure in a wide area with excellent precision.

1 relates to a pressure sensor including a substrate, an elastic film, and a pressure detection thin film.
2 is an X-ray diffraction test result of a thin film showing that the Cu-Zr-based alloy prepared by the sputtering deposition method according to Example 1 of the present invention has an amorphous structure.
3 is an X-ray diffraction test result of a thin film showing that the Cu-Zr-based alloy prepared by the sputtering deposition method according to Comparative Example 1 of the present invention has a crystalline structure.
4 is a scanning electron microscope EDS analysis photograph of a CU-Zr thin film prepared by a sputtering deposition method according to Example 1 of the present invention.
5 is a photograph of a pressure detection thin film processed by a photolithography method of an amorphous alloy thin film manufactured by a sputtering deposition method.
6 is a photograph of a pressure detection thin film obtained by processing an amorphous alloy thin film manufactured by a sputtering deposition method by a laser processing method.
7 shows a stress-strain diagram as a result of a tensile test of a pressure sensor specimen.
8 is a cross-sectional view showing the structure of a general strain gauge.

1 relates to a pressure sensor including a substrate, an elastic film, and a pressure detection thin film.

Referring to Figure 1, the pressure sensor according to an embodiment of the present invention includes a substrate made of at least a part of an amorphous metal; An elastic film disposed on the substrate; And a pressure detection thin film disposed on the elastic film and at least partially made of an amorphous metal, wherein a limit strain of the substrate and the elastic film is greater than or equal to a limit strain of the pressure detection thin film.

The pressure sensor may be used for measuring pressure in a wide range from low to high pressure, such as hydraulic pressure of an automobile engine and general industrial pressure measurement, which requires particularly high precision.

The substrate may be an amorphous thin strip or plate manufactured by a rapid cooling method. Thick amorphous thin strips or plates can also be produced by centrifugal casting.

The centrifugal casting method uses the centrifugal force by rotating the mold at high speed when the molten metal is injected and solidified. Since high pressure is applied to the molten metal, the structure of the casting is dense and there are no pores.

Among the centrifugal casting methods, a thick amorphous thin strip or plate may be manufactured by vacuum centrifugal casting. In the vacuum centrifugal casting method, a Cu can is charged into a mold consisting of an upper mold and a lower mold, heating the mold at 170°C to 230°C under a vacuum atmosphere, and rotating the mold at a predetermined rpm so that a centrifugal force of 70G to 100G is applied. The molten material is injected into the injection space at the center of the mold, and the molten metal supplied to the injection space by centrifugal force is injected into the Cu can loaded in the mold, and the rod is centrifugally cast in the Cu can, and after cooling is completed, the Cu can is acidified. It may be to melt it and take out the rod.

As the amorphous alloy included in the substrate, it may be preferable to use one or more materials selected from Fe, Ni, Cu, Zr, Al, and Mg as a base.

The substrate may be any one of a direct stress type, a bending type, and a shear type.

7 shows a stress-strain diagram as a result of a tensile test of the pressure sensor.

If the substrate is not a direct stress type, but a bending type or a shear type, the strain is stress from the stress-strain diagram of FIG. 7 to the yield strain. Can be proportional to

The yield strain in the stress-strain diagram may mean a yield point when a stress is gradually increased in a material, and a strain rate of the material at the yield point. The yield point may mean a strain when a material subjected to stress in the stress-strain diagram does not maintain elastic strain and starts plastic strain. The elastic deformation may mean a deformation in which a material is deformed when a stress is applied to the material, but when the stress is removed, the deformation of the material is also removed, thereby returning to an original material state. The plastic deformation may mean a deformation in which a material is deformed when a stress is applied to the material, and even if the stress is removed, the deformation of the material is not removed and thus the original material state cannot be restored.

The elastic film disposed on the substrate may be made of a polymer material having thermal stability based on an aromatic main chain. In one example, the elastic film may be a polyimide having excellent mechanical strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring, as well as excellent electrical properties such as insulation properties and low dielectric constant. .

The pressure detection thin film and the substrate may be disposed on the polyimide by using a CN (Cyanoacrylate adhesive) bond having an elastic limit of 2% or more.

The pressure detection thin film at least partially made of an amorphous metal may use a pressure resistance effect in which a resistance value changes when a strain is applied to a metal or semiconductor resistor.

The pressure detection thin film and the substrate may be manufactured by any one of a rapid solidification method and a sputtering deposition method.

The sputtering deposition method is a kind of vacuum deposition method, and it may be a method of generating a plasma in a vacuum state to accelerate a gas such as ionized argon, colliding with a target, ejecting target atoms, and forming a film on a substrate in the vicinity thereof. The sputtering device attaches a magnet to the rear surface of the cathode target to form a magnetic field perpendicular to the electric field, thereby inducing the movement of electrons around the target and extending the movement path to increase sputtering efficiency.

In the rapid solidification method, an amorphous alloy can be produced by rapidly cooling the molten metal at a rate of 1 million° C. or more per second in the process of making the alloy. The rapid solidification method may include an atomization method, a water atomization method, a centrifugal atomization method, and a melt spinning method. In other words, rapid coagulation means that a high cooling rate or large subcooling is used to obtain a fast growth rate of the solid-liquid interface.In the case of a fast growth rate of the solid-liquid interface, the atoms have a chemical potential ( Since we do not have the time to rearrange the atoms so that they have the same potential), solute trapping can occur when a solute atom reaches the solid-liquid interface and enters the solid of the same composition. Therefore, the solid at the solid-liquid interface may not be able to release the solute, so that the composition of the solid and liquid may be the same.

The pressure detection thin film may be made of at least one of Cu, Co, Zr, Ni, and Fe as a base. Preferably, the pressure detection thin film may be made of any one material selected from Zr, Co, and Cu.

In one example, the pressure detection thin film may contain 20 to 70 at% Zr, the remainder of Cu, and other unavoidable impurities with respect to the entire pressure detection thin film, and the thickness of the detection thin film may be 5 μm or less.

In addition, the pressure detection thin film may contain 5 to 20 at% of Si, 5 to 20 at% of B, the remainder of Co and other inevitable impurities with respect to the entire pressure detection thin film. At least one of Cr, Fe, and Ni may be included in an amount of 5 at% or less with respect to the entire detection thin film, and the thickness of the pressure detection thin film may be 10 to 20 μm.

In addition, the pressure detection thin film may contain 5 to 20 at% of Si, 5 to 20 at% of C, the remainder of Co and other inevitable impurities with respect to the entire pressure detection thin film. At least one of Cr, Fe, and Ni may be included in an amount of 5 at% or less with respect to the entire detection thin film, and the thickness of the pressure detection thin film may be 10 to 20 μm.

The limiting strain of the substrate and the elastic film may be greater than or equal to the limiting strain of the pressure detection thin film.

The substrate, the elastic film, and the pressure detection thin film may have a limit strain of 1.5 to 2.5% in a stress-strain diagram.

Example 1: Manufacturing a pressure sensor including a Cu-Zr-based amorphous alloy pressure detection thin film

A substrate to which polyimide was attached was prepared in advance using a CN (Cyanoacrylate adhesive) bond. A substrate to which the polyimide is attached was installed on the anode inside the chamber, and a pure copper target with a diameter of 4 inches and a pure zirconium target with a diameter of 4 inches were installed on the cathode inside the chamber, A permanent magnet was installed under the negative electrode target. Thereafter, after setting the inside of the chamber to a high vacuum state, argon gas was injected into the chamber. Thereafter, plasma was generated by applying a high voltage inside the chamber.

By applying an output of 0.17 kW to the copper target and 0.70 kW to the zirconium target to deposit copper and zirconium on the polyimide-attached substrate, a pressure sensor including a Cu-Zr-based amorphous alloy pressure detection thin film was manufactured.

2 is an X-ray diffraction test result of a thin film showing that the Cu-Zr-based alloy prepared by the sputtering deposition method according to Example 1 has an amorphous structure.

As a result of performing an X-ray diffraction test to analyze the crystal structure of the pressure detection thin film according to Example 1, as shown in FIG. 2, a pattern of a typical amorphous alloy was obtained. The structure of the thin film deposited on the polyimide was amorphous. It has proven to be a structure.

The microstructure of the pressure detection thin film according to Example 1 was observed with a scanning electron microscope (SEM).

4 is a CU-Zr manufactured by the sputtering deposition method according to Example 1 above.

This is a photograph of the EDS analysis of the pressure detection thin film under a scanning electron microscope.

Table 1 shows CU-Zr prepared by the sputtering deposition method according to Example 1 above.

This is the chemical composition result of EDS analysis of the pressure detection thin film under a scanning electron microscope.

According to Table 1, it was confirmed that the pressure-sensing thin film was prepared as an amorphous thin film according to the expression of about 63.99 at% of Cu and about 36.01 at% of Zr.

ingredient Line type Apparent
density k ratio Wt% Wt% Sigma Atomic% Standard Label Factory Standard Cu L series 8.78 0.08780 55.31 0.39 63.99 Pure Element Yes Zr L series 7.54 0.07542 44.69 0.39 36.01 Pure Element Yes Total 100.00 100.00

Comparative Example 1: Preparation of a pressure sensor including a pressure detection thin film of a Cu-Zr-based crystalline alloy

A substrate to which polyimide was attached was prepared in advance using a CN (Cyanoacrylate adhesive) bond. A substrate to which the polyimide is attached was installed on the anode inside the chamber, and a pure copper target with a diameter of 4 inches and a pure zirconium target with a diameter of 4 inches were installed on the cathode inside the chamber, A permanent magnet was installed under the negative electrode target. Thereafter, after setting the inside of the chamber to a high vacuum state, argon gas was injected into the chamber. Thereafter, plasma was generated by applying a high voltage inside the chamber.

By applying an output of 0.15 kW to the copper target and 0.70 kW to the zirconium target to deposit copper and zirconium on the polyimide-attached substrate, a pressure sensor including a Cu-Zr-based crystalline alloy pressure detection thin film was manufactured.

3 is an X-ray diffraction test result of a thin film showing that the Cu-Zr-based alloy prepared by the sputtering deposition method according to Comparative Example 1 has a crystalline structure.

As a result of performing an X-ray diffraction test to analyze the crystal structure of the pressure detection thin film according to Comparative Example 1, as shown in FIG. 3, a pattern of a typical crystalline alloy is shown. Therefore, it was proved that the structure of the thin film deposited on the polyimide is a crystalline structure.

Example 2: Preparation of a pressure sensor including a pressure detection thin film of a Co-Si-B-based amorphous alloy

Amorphous alloy with a thickness of 10 μm using a CN (Cyanoacrylate adhesive) bond (EDS analysis: 68 at% of Co, 13 at% of Si) on a substrate to which a polyimide film is attached using a CN (Cyanoacrylate adhesive) bond , Cr 4at%, Fe 4at%, B 11at%) was attached to the polyimide film to prepare a strain gauge thin plate. Thereafter, while rotating the thin plate, a liquid photoresist was applied to spread evenly (Spin Coating). Thereafter, it was heated at 70° C. for 20 minutes to remove the solvent to form a PR (Photoresist) film. After preparing a photomask, which is a transparent film engraved with an array pattern, the photomask was fixed on the PR film. Thereafter, exposure treatment was performed in which UV was applied onto the photomask. Due to the exposure treatment, the array pattern engraved on the photomask was transferred onto the PR (Photoresist) film. Then, the array pattern was developed on the wafer using a developing solution in which distilled water and sodium carbonate were mixed in a weight ratio of 100:1. Hydrochloric acid: hydrogen peroxide = 1: 1 After making an etching solution in a weight ratio, the Co-based ribbon was immersed for 2 minutes to remove the PR (Photoresist) film, and a pressure sensor including a Co-Si-B-based amorphous alloy pressure detection thin film was prepared. Was prepared.

The pressure sensor manufactured in Example 2 has a limiting elastic strain of 2.0% or more, and may have excellent corrosion resistance.

The physical properties of the pressure sensor finally manufactured including the substrate and strain gauge manufactured using the amorphous alloy manufactured in Examples 1 and 2 were evaluated, and the results are shown in Table 2 below.

division Example 1 Example 2 Usable temperature -20 ℃ ~ 80 ℃ -20 ℃ ~ 70 ℃ Pressure detection film width 5 mm 4 mm Vertical length of the pressure detection film 10 mm 12 mm Pressure detection film thickness 0.003 mm 0.005 mm Weighing range 500 kg or less 500 kg or less Input sensor accuracy 0.001 kg or less 0.001 kg or less

100: pressure sensor
110: pressure detection thin film
120: elastic body
130: substrate

Claims (7)

A substrate made of an amorphous metal;
An elastic film disposed on the substrate and made of polyimide; And
Includes; a pressure detection thin film disposed on the elastic film and made of an amorphous metal,
The limit strain of the substrate and the elastic film is greater than or equal to the limit strain of the pressure detection thin film,
Arrangement of the pressure detection thin film and the substrate on the polyimide is attached using a CN (Cyanoacrylate adhesive) bond having an elastic limit of 2% or more,
The substrate, the elastic film, and the pressure detection thin film,
In the stress-strain diagram, the strain at which elastic strain changes to plastic strain is 1.5 to 2.5%,
The pressure detection thin film is a Cu-Zr-based amorphous alloy containing 20 to 70 at% Zr, the balance Cu and other inevitable impurities with respect to the entire pressure detection thin film,
Including any one of amorphous alloys of Co-Si-B-based amorphous alloys containing 5 to 20 at% of Si, 5 to 20 at% of B, the remainder of Co and other inevitable impurities with respect to the entire pressure detection thin film,
The thickness of the pressure detection thin film made of the Cu-Zr-based amorphous alloy is 5 μm or less,
The thickness of the pressure detection thin film made of the Co-Si-B-based amorphous alloy is 10 to 20 μm,
The Co-Si-B-based pressure detection thin film contains 5 at% or less of at least one of Cr, Fe, and Ni with respect to the entire pressure detection thin film,
Pressure sensor using amorphous alloy.
delete delete delete delete The method of claim 1,
The substrate is any one of a bending type and a shear type,
Pressure sensor using amorphous alloy.
The method of claim 1,
The pressure detection thin film and substrate are manufactured by any one of a rapid solidification method and a sputtering deposition method,
Pressure sensor using amorphous alloy.

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