MEMS Power Inductor with Crack-Resistant Magnetic Laminations
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Solution Overview
Problem
MEMS power inductors face challenges with photo-patternable materials that are either brittle and prone to cracking, leading to environmental contamination, or have high aspect ratios that minimize eddy currents but are not crack-resistant, resulting in unacceptably large eddy currents.
Innovation Solution
The use of a high aspect ratio material for magnetic laminations surrounded by a low aspect ratio material with high crack resistance to protect against cracking and environmental contaminants, while maintaining thin laminations to minimize eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a high aspect ratio material is used for magnetic laminations, then eddy currents are minimized, but crack resistance deteriorates
Solution Approach 1:
The patent uses a composite structure where a high aspect ratio material (providing low eddy currents) is combined with a low aspect ratio material (providing crack resistance). The low aspect ratio material surrounds and protects the high aspect ratio material, creating a composite system that achieves both minimal eddy currents and high crack resistance simultaneously.
2Reliability
If a low aspect ratio material with high crack resistance is used, then crack resistance is improved, but eddy currents increase
Solution Approach 1:
The patent employs a composite material system where the low aspect ratio material (with high crack resistance) is combined with the high aspect ratio material (with low eddy currents). The low aspect ratio material serves as a protective surrounding structure, while the high aspect ratio material forms the magnetic laminations, achieving both crack resistance and low eddy current losses.
3Loss of energy
If magnetic laminations are made thin to minimize eddy currents, then eddy currents are reduced, but structural integrity deteriorates
Solution Approach 1:
The patent creates a composite structure where thin high aspect ratio magnetic laminations (which minimize eddy currents) are surrounded and supported by a low aspect ratio material with high mechanical strength. This composite arrangement provides the necessary structural integrity to the thin laminations while maintaining low eddy current losses.
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 approach effectively reduces eddy currents and enhances crack resistance, ensuring the magnetic laminations remain functional and resistant to environmental exposure.
Implementation Method 1
A current can flow into inductor 200 through bond pad structure 314A and out through bond pad structure 314B. A current can also flow in the opposite direction, flowing into inductor 200 through bond pad structure 314B and out through bond pad structure 314A.
Implementation Method 2
One advantage of SU-8 is that SU-8 has a high aspect ratio, which means that SU-8 can be formed to have openings that are much deeper than the widths of the openings. Magnetic laminations formed in deep narrow openings are thin and thereby minimize eddy currents.
Data Source
AI summary
Magnetic laminations are formed in the openings of a first non-conductive structure, which is formed in the opening of a second non-conductive structure that has a maximum aspect ratio that is less than the maximum aspect ratio of the first non-conductive structure. The second non-conductive structure is more crack resistant than the first non-conductive structure, and thereby protects the first non-conductive structure and the magnetic laminations from environmental contaminants.