Current Detection Device Shield Layer Flatness
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Solution Overview
Problem
The existing current detection devices face issues with the deterioration of the feedback coil and shield layer due to the use of organic insulating layers, leading to decreased bonding strength and stress concentration, which results in cracks and a reduced dynamic range of current measurement.
Innovation Solution
A current detection device with a multilayer structure featuring a coil layer with a planar helical pattern, a height adjustment layer made of nonmagnetic metal, and an upper insulating layer of inorganic material, where the shield layer covers both layers without large stepped portions, preventing heat stress concentration and maintaining a flat shape to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an organic insulating layer is used to cover the feedback coil, then the manufacturing process is simplified, but the layer deteriorates the feedback coil and shield layer due to hygroscopic properties and swelling, decreasing bonding strength
Solution Approach 1:
The patent changes the material parameter of the upper insulating layer from organic material to inorganic material (such as silicon nitride SiNx). This parameter change eliminates the hygroscopic properties and swelling issues inherent in organic materials, thereby preventing deterioration of the feedback coil and shield layer while maintaining manufacturing feasibility through CVD or spattering processes.
Solution Approach 2:
The patent employs a composite structure where an inorganic insulating layer is combined with a magnetic shield layer and feedback coil. This composite material approach allows the inorganic layer to provide both electrical insulation and dimensional stability, preventing the bonding strength degradation that occurs with organic materials while maintaining the functional integrity of the feedback coil assembly.
2Reliability
If an inorganic insulating layer is used to cover the feedback coil, then bonding strength is improved, but large stepped portions are produced at the surface, causing stress concentration and crack formation during heating processes
Solution Approach 1:
The patent introduces a height adjustment layer as an intermediary element between the feedback coil and the upper insulating layer. This intermediate layer compensates for the height differences created by the coil structure, providing a flat surface for the insulating layer and eliminating stepped portions that would otherwise cause stress concentration and cracking during thermal processing.
Solution Approach 2:
The height adjustment layer is strategically positioned only at specific locations where height compensation is needed - namely at the side portions of the feedback coil. This localized application of the adjustment layer addresses the surface flatness issue precisely where it occurs without adding unnecessary material or complexity to other regions of the structure.
3Area of stationary object
If the shield layer is formed to cover stepped portions, then coverage is improved, but heat stress concentrates at the stepped portions, leading to crack formation in the upper insulating layer
Solution Approach 1:
The height adjustment layer serves as a mediator that eliminates the stepped portions before the shield layer is applied. By providing a flat surface foundation, it allows the shield layer to be formed uniformly without having to accommodate height variations, thereby preventing stress concentration at stepped portions while maintaining adequate coverage of the feedback coil.
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 configuration prevents crack formation in the upper insulating layer, maintains the shield effect, and increases the dynamic range and linearity of current measurement, while ensuring the shield layer remains flat and effective.
Implementation Method 1
a magnetoresistive element and a feedback coil face a conductor through which a current to be measured passes. A current magnetic field excited by the current that is to be measured and that flows through the conductor is detected by the magnetoresistive element
Implementation Method 2
a shield layer is disposed between the conductor through which a current to be measured flows and the feedback coil. The shield layer weakens the current magnetic field induced by the current to be measured
Data Source
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AI summary
[Object] To provide a current detection device capable of preventing a crack in an insulating layer by forming a flat shield layer on a feedback coil and enhancing saturated magnetization in the shield layer. [Solution] Magnetic detectors 11, 12, 13, and 14 and a lower insulating layer 4 covering the magnetic detectors 11, 12, 13, and 14 are disposed on a substrate 2. On the lower insulating layer 4, a coil layer 35 including a plurality of segments forming a counter detector 30a of a feedback coil 30 is disposed. Height adjustment layers 36 and 37 are disposed on both sides of the coil layer 35. The coil layer 35 and the height adjustment layers 36 and 37 are covered with an upper insulating layer 9, and a shield layer 3 is disposed thereon. Accordingly, the shield layer 3 can be made substantially flat.