MR Magnetic Sensor Lead Layout for Low-Resistance Miniaturization
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Solution Overview
Problem
Magnetic sensors face challenges in miniaturization due to increased wiring resistance when connecting magnetoresistive elements in series, particularly when the sensor is designed to detect magnetic fields perpendicular to the substrate surface.
Innovation Solution
The magnetic sensor design includes a soft magnetic body with leads that overlap the soft magnetic body, reducing wiring resistance by allowing the leads to pass under the soft magnetic body, thereby minimizing the width of the wiring and maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the area of occupancy of magnetoresistive elements is increased to enhance sensitivity, then sensitivity is improved, but the width of wiring is reduced leading to increased wiring resistance
Solution Approach 1:
The lead extends in the vertical direction (third direction) by passing under the soft magnetic body, utilizing the vertical dimension to achieve electrical connection. This dimensional transition allows the lead to occupy space above the soft magnetic body when viewed from the top, effectively increasing the available planar area for magnetoresistive elements without compromising wiring width or increasing resistance.
2Area of stationary object
If magnetoresistive elements are arranged along a long structure like a yoke in series, then coverage area is improved, but wiring resistance increases due to reduced wiring width
Solution Approach 1:
The lead transitions from a planar arrangement to a three-dimensional configuration by extending under the soft magnetic body in the vertical direction. This allows the lead to carry current along the long structure while maintaining adequate width through the vertical space, thereby reducing wiring resistance even as the coverage area increases.
Solution Approach 2:
The lead is positioned to pass under the soft magnetic body, nesting the lead within the spatial envelope defined by the soft magnetic body structure. This nesting arrangement allows the lead to utilize the space above the soft magnetic body for electrical connection, effectively decoupling the wiring width from the planar coverage area.
3Volume of moving object
If device miniaturization is pursued, then device size is reduced, but wiring resistance increases due to narrower wiring
Solution Approach 1:
The lead utilizes the vertical dimension to extend above the soft magnetic body, allowing the wiring to maintain adequate width in the vertical direction while the device footprint in the planar direction is minimized. This dimensional separation enables miniaturization of the device area without proportionally increasing wiring resistance.
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
This design reduces wiring resistance and allows for miniaturization of the magnetic sensor while maintaining sensitivity, addressing the issue of increased resistance in miniaturized devices.
Implementation Method 1
The magnetic field conversion elements convert a magnetic field in a direction perpendicular to the surface of the substrate into a magnetic field in a direction parallel to the surface of the substrate
Implementation Method 2
a free layer having a magnetization whose direction is variable depending on the direction of an applied magnetic field
Data Source
AI summary
A magnetic sensor includes a soft magnetic body having a first end surface and a second end surface located on opposite sides, a first MR element located near the first end surface, a second MR element located near the second end surface, and a first lead that electrically connects the first MR element and the second MR element and includes a portion overlapping the soft magnetic body when observed in a second direction orthogonal to a first direction in which the first and second MR elements are arranged.