Multi-Layer Magnetic Shield for Hall Sensor Stray Field Reduction
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Solution Overview
Problem
Stray magnetic fields from power lines or nearby electronics degrade the sensing accuracy of Hall effect sensors and other magnetic field-sensitive devices, as they cannot differentiate the source of contributing magnetic fields.
Innovation Solution
A multi-layer magnetic shield structure is applied over the substrate of a sensor, comprising a seed layer and multiple magnetic shield layers with high magnetic permeability, formed using electroplating technology, to reduce the impact of stray magnetic fields. The shield layers are made of materials like nickel, cobalt, iron, and their alloys, and are strategically placed over the substrate's sides to encase the sensor, minimizing magnetic flux leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic shield layer is added over the sensor substrate, then sensing accuracy is improved by reducing stray field interference, but device complexity increases due to the additional multi-layer magnetic structure
Solution Approach 1:
The magnetic shield is divided into multiple discrete magnetic shield layers (first magnetic shield layer, second magnetic shield layer, etc.) positioned at different heights relative to the sensor substrate. Each layer can be independently formed and optimized, allowing the system to achieve comprehensive shielding while maintaining manageable structural complexity through modular segmentation.
Solution Approach 2:
The magnetic shield structure extends into the vertical dimension by positioning multiple magnetic shield layers at different heights above and below the sensor substrate. This three-dimensional multi-layer configuration provides comprehensive magnetic field blocking from multiple directions simultaneously, improving shielding effectiveness without requiring a single complex shield structure.
2Object-affected harmful factors
If multiple magnetic shield layers are formed using electroplating, then shielding effectiveness is improved by concentrating magnetic flux, but manufacturing complexity increases due to the multi-step electroplating process
Solution Approach 1:
A non-magnetic seed layer is formed on the sensor substrate before depositing the magnetic shield layers. This preliminary seed layer preparation ensures proper adhesion and provides a controlled surface for subsequent electroplating, simplifying the manufacturing process by establishing a foundation that guides the magnetic material deposition.
Solution Approach 2:
The non-magnetic seed layer acts as an intermediary between the sensor substrate and the magnetic shield layers. It provides a compatible surface for electroplating, facilitates controlled magnetic material deposition, and enables proper adhesion without requiring direct bonding between dissimilar materials, thereby simplifying the manufacturing process.
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
The multi-layer magnetic shield significantly reduces stray magnetic field intensity at the sensor by up to 100 times, enhancing the signal-to-noise ratio and improving sensing accuracy by concentrating magnetic flux in high permeability materials and minimizing it in lower permeability regions, thus effectively shielding the sensor from external magnetic interference.
Implementation Method 1
A magnetic shield layer is formed over the seed layer on the set of outer surfaces of the structure. The magnetic shield layer is formed of a material having a high magnetic permeability... significantly reduces stray magnetic field intensity at the sensor by up to 100 times... concentrating magnetic flux in high permeability materials
Implementation Method 2
formed using electroplating technology
Data Source
AI summary
In a described example, a structure includes a substrate having a surface with multiple sides. A sensor is positioned within the substrate and a seed layer is over at least four sides of the surface of the substrate. A magnetic shield layer is over the seed layer for the at least four sides of the surface of the substrate.