Strain gage and manufacturing method thereof

• US 8,640,549 B2
• Filed: 03/27/2012
• Issued: 02/04/2014
• Est. Priority Date: 03/30/2011
• Status: Active Grant

• Current Assignee: Minebea Mitsumi, Inc.
• Original Assignee: Minebea Company Limited (MinebeaMitsumi Inc.)
• Inventors: Inamori, Dohaku
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US13/430,994
• Publication Number:
  US 20120247220A1
• Time in Patent Office: 679 Days
• Field of Search: 737/66, 737/74, 738/623.81
• US Class Current: 73/766
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01L 1/2281 for temperature variations
• CPC Class Codes: G01L 1/2293 of the semi-conductor type semi-conductor devices controllable by variations of applied mechanical force H01L29/84

Abstract

A strain gage includes a strain sensitive element; and a temperature compensation element, wherein the strain sensitive element and temperature compensation element are monolithically formed. A method of manufacturing the strain gage includes: exposing and developing a strain sensitive element pattern and the temperature compensation element pattern; and etching the strain sensitive element pattern and the temperature compensation element pattern.

Claims

1. A strain gage comprising:

a strain sensitive element; and

a temperature compensation element,

wherein the strain sensitive element and temperature compensation element are monolithically formed,

wherein the temperature compensation element is configured by;

a first layer made of a first material, which is the same as a material of the strain sensitive element; and

a second layer made of a second material, which is a different from the first material, wherein the second layer is formed on the first layer.

2. The strain gage according to claim 1,

wherein a plurality of the strain sensitive elements are provided, and

wherein a full-bridge circuit is configured by the plurality of the stress sensitive elements and the temperature compensation element.

3. The strain gage according to claim 2,

wherein an output temperature compensation element is arranged on an input side.

4. The strain gage according to claim 3,

wherein the temperature compensation element and the output temperature compensation element have temperature compensation resistances, respectively.

5. The strain gage according to claim 1,

wherein the second material has lower specific resistance and higher temperature coefficient of resistance than the first material.

6. The strain gage according to claim 5,

wherein the second material is one of Cu and Ni,

wherein, in case that the second material is Cu, the first material is CuNi, and

wherein, in case that the second material is Ni, the first material is NiCr.

7. A method of manufacturing a strain gage, comprising the sequential steps of:

producing a laminated sheet composed of a metal foil and a sheet-like resin material;

applying and drying a first resist;

exposing and developing a temperature compensation element pattern;

depositing a film;

peeling off the first resist;

applying and drying a second resist;

exposing and developing a strain sensitive element pattern and the temperature compensation element pattern;

etching the strain sensitive element pattern and the temperature compensation element pattern; and

peeling off the second resist.