Multi-Layer Inductor Through-Conductor Layout to Prevent Cracks
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Solution Overview
Problem
Conventional multi-layer inductors face issues with cracks due to internal stress generated from differing shrinkage rates of magnetic material layers and conductive paste during sintering.
Innovation Solution
The multi-layer inductor design incorporates a through conductor comprising a pair of extracting conductors and internal conductors, where the end portions of these conductors overlap and are connected, with the overall conductor length being shorter than a single continuous conductor, reducing shrinkage and internal stress, thereby preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single continuous through conductor is used, then electrical connection is simplified, but internal stress increases causing cracks
Solution Approach 1:
The through conductor is divided into multiple separate conductor portions, each extending through a limited number of magnetic material layers. These segmented conductors are arranged in parallel rather than forming a single continuous path, which reduces the total length of each conductor and consequently reduces internal stress and shrinkage during sintering while maintaining electrical connectivity through the element body.
2Reliability
If conductor length is reduced, then internal stress decreases preventing cracks, but electrical connection path increases
Solution Approach 1:
Multiple separate conductor portions are electrically connected through external electrodes formed on the magnetic material layers. The external electrodes merge the discontinuous conductor portions into a continuous electrical path, achieving both crack prevention through shortened conductors and maintained electrical connectivity through the combining function of external electrodes.
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 design effectively prevents cracks in the inductor by minimizing internal stress and ensuring stable electrical connections between the conductors and external electrodes.
Implementation Method 1
The above-described element body of the inductor according to the conventional art is a sintered body (sintered element body) obtained by sintering a plurality of magnetic material layers stacked. The through conductor is obtained by sintering the conductive paste applied on the magnetic material layer together with the magnetic material layer.
Implementation Method 2
the shrinkage rate of the magnetic material layer and the shrinkage rate of the conductive paste at the time of sintering are different
Data Source
AI summary
In the multi-layer inductor, a through conductor provided in a sintered element body includes a pair of extracting conductors and a pair of internal conductors, and an end portion of the extracting conductor and an end portion of the internal conductor overlap each other in a stacking direction of the element body. Thus, the amount of shrinkage of each conductor during sintering of the element body is reduced, and internal stress generated in the element body after sintering is prevented.