Strain gauge with improved stability

Patent metadata

Field	Value
Publication number	US-11692806-B2
Application number	US-201816650553-A
Country	US
Kind code	B2
Filing date	Sep 26, 2018
Priority date	Sep 29, 2017
Publication date	Jul 4, 2023
Grant date	Jul 4, 2023

Abstract

A strain gauge includes a flexible resin substrate; a functional layer formed of a metal, an alloy, or a metal compound, directly on one surface of the substrate; a resistor formed of a film including Cr, CrN, and Cr2N, on one surface of the functional layer; and an insulating resin layer with which the resistor is coated.

First claim

The invention claimed is:

1. A strain gauge comprising:
a flexible resin substrate;
a functional layer formed of a metal, an alloy, or a metal compound, directly on one surface of the substrate;
a resistor formed of a film including Cr, CrN, and Cr 2 N, on one surface of the functional layer; and
an insulating resin layer with which the resistor is coated,
wherein the substrate has an expansion coefficient in a range of from 7 ppm/K to 20 ppm/K.

2. The strain gauge according to claim 1 , wherein the functional layer includes a function of promoting crystal growth of the resistor.

3. The strain gauge according to claim 1 , wherein surface unevenness on the one surface of the substrate is 15 nm or less, and
wherein the resistor has a film thickness of 0.05 μm or more.

4. The strain gauge according to claim 1 , further comprising electrodes electrically coupled to the resistor,
wherein each electrode includes:
a terminal section extending from a corresponding end portion from among end portions of the resistor;
a first metallic layer formed of copper, a copper alloy, nickel, or a nickel alloy, on or above the terminal section; and
a second metallic layer formed of material having better solder wettability than the first metallic layer, on or above the first metallic layer.

5. The strain gauge according to claim 1 , further comprising an insulating layer formed of material having higher resistance than the resistor and the insulating resin layer, the insulating layer being provided in a lower layer of the insulating resin layer, and the resistor is being coated with the insulating layer.

6. The strain gauge according to claim 1 , wherein a main component of the resistor is alpha-chromium.

7. The strain gauge according to claim 6 , wherein the resistor includes alpha-chromium of 80% by weight or more.

8. The strain gauge according to claim 6 , wherein the functional layer includes titanium.

9. The strain gauge according to claim 8 , wherein the resistor includes titanium.

10. The strain gauge according to claim 8 , wherein the resistor includes titanium nitride.

11. A sensor module comprising:
the strain gauge according to claim 1 ; and
a flexure element disposed on another surface of the substrate.

12. A strain gauge comprising:
a flexible resin substrate;
a functional layer formed of a metal, an alloy, or a metal compound, directly on one surface of the substrate;
a resistor formed of a film that includes Cr, CrN, and Cr 2 N and into which an element included in the functional layer is diffused, on one surface of the functional layer; and
an insulating resin layer with which the resistor is coated,
wherein a gauge factor of the strain gauge is 10 or more, and
wherein the substrate has an expansion coefficient in a range of from 7 ppm/K to 20 ppm/K.

13. A strain gauge comprising:
a flexible resin substrate;
a functional layer formed of a metal, an alloy, or a metal compound, directly on one surface of the substrate;
a resistor formed of a film that includes Cr, CrN, and Cr 2 N and into which an element included in the functional layer is diffused, on one surface of the functional layer; and
an insulating resin layer with which the resistor is coated,
wherein a temperature coefficient of resistance of the strain gauge is in a range of from −1000 ppm/° C. to +1000 ppm/° C., and
wherein the substrate has an expansion coefficient in a range of from 7 ppm/K to 20 ppm/K.

Assignees

• Minebea Mitsumi Inc

Inventors

• Misaizu Eiji
• Yuguchi Akiyo
• Adachi Shigeyuki
• Asakawa Toshiaki
• Kitamura Atsushi

Classifications

• G01L1/2287

  constructional details of the strain gauges (adjustable resistors H01C10/00) · CPC title

• C22C38/42

  with copper · CPC title

• G01B7/16

  for measuring the deformation in a solid, e.g. by resistance strain gauge · CPC title

• G01B7/18 Primary

  using change in resistance · CPC title

• G01L1/2268 Primary

  Arrangements for correcting or for compensating unwanted effects · CPC title