Multilayer Coil Structure With Stress Relief Against Sintering Cracks
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Solution Overview
Problem
Conventional multilayer coil components experience cracking due to differences in shrinkage ratios between element body portions with different material compositions, leading to stress concentration and potential failure.
Innovation Solution
A multilayer coil component with a stress alleviation portion in the inner region, formed as a slit layer, alleviates stress concentration by reducing the impact of differing shrinkage ratios between element body portions, and includes intermediate layers of mixed composition to minimize cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If element body portions of different material compositions are laminated to adjust coil characteristics, then coil characteristics (impedance, inductance, SRF) can be adjusted, but cracking occurs due to difference in shrinkage ratio between element body portions
Solution Approach 1:
The patent introduces a stress alleviation portion with different material properties (lower shrinkage ratio) specifically in the inner region where stress concentrates. This local modification allows the majority of the element body to maintain different material compositions for coil characteristic adjustment, while the stress alleviation portion locally addresses the shrinkage ratio difference problem to prevent cracking.
Solution Approach 2:
The stress alleviation portion acts as an intermediary element between the element body portions with different shrinkage ratios. It mediates the stress concentration by providing a region with intermediate or lower shrinkage characteristics, thereby preventing direct stress transfer that would cause cracking between the different material portions.
2Manufacturing precision
If multilayer structure with different material compositions is used, then coil characteristics can be optimized, but stress concentration in inner region leads to cracking
Solution Approach 1:
The stress alleviation portion is specifically positioned in the inner region where stress concentrates during sintering. This localized modification maintains the overall multilayer structure with different material compositions for precise coil characteristics, while locally reducing stress concentration to preserve structural integrity.
Solution Approach 2:
The stress alleviation portion is designed in advance to cushion the stress that will arise during the sintering process. By pre-positioning this low-shrinkage region in the inner layer, the structure is prepared to absorb and distribute shrinkage stresses before they can cause cracking, thereby maintaining both manufacturing precision and structural strength.
Data Source
AI summary
A multilayer coil component includes an element body having a multilayer structure including a first element body portion formed of a ferrite element body material, and a second element body portion laminated on the first element body portion and formed of a ferrite element body material having a composition different from the ferrite element body material forming the first element body portion, a multilayer coil having an axis parallel to a lamination direction of the element body, and a stress alleviation portion provided in an inner region of the multilayer coil when viewed from the lamination direction. In the multilayer coil component, the stress alleviation portion is provided in the inner region of the multilayer coil in which a stress tends to be concentrated to alleviate the stress in the inner region of the multilayer coil, and thereby occurrence of cracking in the element body can be suppressed.