Fluxgate Magnetometer Core Encapsulation for Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of fluxgate magnetometers into integrated circuits poses challenges due to high stress from large magnetic cores, leading to delamination and cracking, which limits the size and thickness of the magnetic core.
Innovation Solution
Encapsulating the magnetic core with a layer of nonmagnetic metal or alloy, such as titanium, to provide stress relaxation and prevent delamination, allowing for larger dimensions while reducing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large magnetic cores are used in fluxgate magnetometers, then measurement sensitivity is improved, but stress-induced delamination and cracking occur
Solution Approach 1:
A stress relaxation layer comprising a first layer and a second layer is introduced between the magnetic core and the surrounding dielectric structure. The first layer is in contact with the magnetic core and has a first stress relaxation modulus, while the second layer has a second stress relaxation modulus. This intermediary layered structure allows differential stress management, where each layer can be optimized for specific stress conditions, thereby preventing delamination and cracking while preserving the benefits of large magnetic core dimensions for improved measurement sensitivity.
2Measurement precision
If magnetic core size is increased, then fluxgate magnetometer performance is enhanced, but stress on integrated circuit increases
Solution Approach 1:
The stress relaxation layer introduces a gradient in stress relaxation modulus through its layered structure. The first layer in contact with the magnetic core has a different stress relaxation modulus than the second layer, creating a parameter gradient that progressively manages stress from the magnetic core outward to the dielectric. This parameter change approach allows the system to accommodate larger magnetic cores with enhanced performance while distributing and reducing the stress transmitted to the integrated circuit substrate.
3Measurement precision
If magnetic core thickness is increased, then measurement capability is improved, but cracking in surrounding dielectric increases
Solution Approach 1:
The stress relaxation layer acts as an intermediary buffer between the thick magnetic core and the surrounding dielectric material. By positioning this layered structure at the interface, it absorbs and redistributes the stress generated by thick magnetic cores, preventing direct stress transmission to the dielectric that would cause cracking. This allows the magnetic core thickness to be increased for improved measurement capability without suffering from dielectric cracking.
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 encapsulation significantly reduces stress-related cracking and delamination, enabling the formation of larger magnetic cores without yield loss, thereby enhancing the integration of fluxgate magnetometers in integrated circuits.
Implementation Method 1
The layer of nonmagnetic metal or nonmagnetic alloy provides stress relaxation between the magnetic core material and the surrounding dielectric
Data Source
AI summary
An integrated circuit includes a fluxgate magnetometer. The magnetic core of the fluxgate magnetometer is encapsulated with a layer of encapsulant of a nonmagnetic metal or a nonmagnetic alloy. The layer of encapsulate provides stress relaxation between the magnetic core material and the surrounding dielectric. A method for forming an integrated circuit has the magnetic core of a fluxgate magnetometer encapsulated with a layer of a nonmagnetic metal or nonmagnetic alloy to eliminate delamination and to substantially reduce cracking of the dielectric that surrounds the magnetic core.