Laminated Common-Mode Choke Insulation via Segregated Al Regions
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Solution Overview
Problem
Laminated common-mode choke coils with glass ceramic layers face challenges in maintaining insulation reliability due to silver diffusion, which can lower the insulation properties and lead to a drop in resistance when segregated Al regions form, potentially causing cross-linking and network formation.
Innovation Solution
Incorporating segregated Al regions within the glass ceramic layer, where Al is concentrated at least 1.5 times higher than in other areas, with a maximum dimension not exceeding 80% of the distance between internal conductors, to capture diffused silver and other conductor materials, preventing cross-linking and enhancing insulation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass ceramics with alumina-spiked filler is used as the insulator layer material, then chemical resistance is improved, but the dielectric constant increases
Solution Approach 1:
The patent adjusts the chemical composition parameters of the glass ceramics by specifying alumina content within 0.1-10 wt% and controlling the ratio of alumina to silica. This parameter optimization allows the material to achieve both improved chemical resistance and maintained low dielectric constant, resolving the contradiction between these two properties.
2Ease of manufacture
If Ag is used as the internal conductor material, then sintering in atmosphere is simplified, but insulation property deteriorates due to Ag diffusion
Solution Approach 1:
The patent introduces an intermediary alumina-spiked glass ceramic layer between the Ag conductors and the surrounding environment. This intermediate layer acts as a diffusion barrier that prevents Ag from migrating into adjacent layers, thereby maintaining insulation properties while allowing Ag to remain as the conductor material for simplified atmospheric sintering.
3Reliability
If the glass ceramic layer thickness is reduced to minimize Ag diffusion distance, then insulation reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent creates a composite glass ceramic material with alumina particles dispersed in the glass matrix. This composite structure provides both diffusion barrier functionality and mechanical integrity, allowing the layer to maintain adequate thickness for manufacturing tolerance while the alumina network prevents Ag diffusion pathways.
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 presence of segregated Al regions effectively captures diffused conductor materials, maintaining insulation properties and improving the reliability of laminated common-mode choke coils by preventing a drop in resistance and ensuring higher insulation reliability.
Implementation Method 1
the glass ceramic layer contains segregated Al regions (20)
Implementation Method 2
the insulator layer between the two conductors has a low dielectric constant
Implementation Method 3
Ag easily diffuses in the glass ceramic layer
Data Source
AI summary
A laminated common-mode choke coil offering higher insulation reliability has a glass ceramic layer, two spiral internal conductors facing each other and sandwiching the glass ceramic layer in between, and insulation layers sandwiching the two internal conductors, wherein the glass ceramic layer contains segregated Al regions and the maximum dimension t1 of each segregated Al region in the glass ceramic layer, in the layer-thickness direction, is no more than 80% of the distance t0 between the two internal conductors.