Magnetic Sensor Inclined Support for Uniform MR Element Thickness

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Solution Overview

Problem

Magnetoresistive elements formed on curved surfaces experience significant thickness variations due to manufacturing process inaccuracies, leading to inconsistent performance.

Innovation Solution

A magnetic sensor design with a support member featuring an inclined portion that minimizes curvature changes, ensuring consistent thickness of the magnetoresistive element by maintaining specific angles and curvature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the magnetoresistive element is formed on a curved surface by ion milling or reactive ion etching, then the element can be created with the desired shape, but the thickness of the element changes greatly near the edge due to variations in photoresist mask position and dimensions

Engineering Contradiction:

Improvethickness uniformityVSAvoidphotoresist mask positioning sensitivity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies a curvature correction principle by designing the inclined portion with a specific curvature radius that compensates for the bulging effect. The curvature radius is set to satisfy a specific mathematical relationship with the inclination angle, which counteracts the thickness variation caused by the bulging curved surface during etching, thereby achieving uniform thickness despite the curved geometry

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the geometric parameters of the inclined portion by precisely controlling the curvature radius and inclination angle. These parameter adjustments are designed to offset the bulging effect, transforming the thickness distribution from non-uniform to uniform across the magnetoresistive element while maintaining the curved surface structure

Inventive Principle:

Principle #35Parameter changes

2Shape

If the inclined surface is formed as a curved surface bulging out due to the manufacturing process, then the surface can be created, but the amount of change in thickness increases with distance from the top of the curved surface

Engineering Contradiction:

Improvecurved surface formationVSAvoidthickness control

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent intentionally designs the inclined portion with a specific curvature radius that satisfies a mathematical relationship with the inclination angle. This controlled curvature counteracts the unwanted bulging effect, ensuring that the thickness remains uniform across the element while maintaining the curved surface shape necessary for the application

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Ease of manufacture

If the photoresist mask position or dimensions vary due to photolithography precision, then mask fabrication is flexible, but the thickness of the magnetoresistive element changes greatly near the edge

Engineering Contradiction:

Improvephotoresist mask fabrication flexibilityVSAvoidelement thickness uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent designs the inclined portion with a specific curvature radius that compensates for photoresist mask positioning variations. The curvature is calculated to satisfy a specific relationship with the inclination angle, which counteracts the thickness variation caused by mask position or dimension variations, thereby achieving uniform thickness despite manufacturing tolerances

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent applies a compensation design in advance by setting the curvature radius and inclination angle to specific values that preemptively counteract the expected thickness variations from photoresist mask variations. This beforehand cushioning ensures that even with normal manufacturing tolerances, the final element thickness remains uniform

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Reduces thickness variations of the magnetoresistive element, enhancing the sensor's reliability and performance by stabilizing the resistance changes in response to external magnetic fields.

Implementation Method 1

a magnetoresistive element whose resistance changes with an external magnetic field

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS12392845B2Magnetic sensor including electrode disposed on inclined portion whose curvature changes

Publication Date: 2025.08.19 TDK CORP

AI summary

A magnetic sensor includes an MR element and a support member. The support member has an opposed surface including a first inclined portion, and a bottom surface. In a given cross section, the first inclined portion is inclined at a first angle at a first position, and inclined at a second angle smaller than the first angle at a second position. The absolute value of a curvature of the first inclined portion at the first position is less than the absolute value of the curvature of the first inclined portion at the second position. The MR element is provided on the first inclined portion so that the first edge is located above the first position in a given cross section.