Ceramic Substrate Terminal Electrode Structure for Crack Suppression
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Solution Overview
Problem
Existing multilayer ceramic substrates face issues with cracks forming at the terminal electrode due to thermal stress, which can disrupt electrical conductivity by concentrating stress at the outer periphery and potentially fracturing inner conductors.
Innovation Solution
A ceramic substrate design with a terminal electrode structure comprising a first electrode with 3-40% non-conductive component content and a second electrode with 0-10% non-conductive component content, where the first electrode strongly adheres to the base body and the second electrode weakly adheres to the insulating layer, controlling crack growth and maintaining reliable electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the base layer is made thin to reduce overall electrode thickness, then device compactness is improved, but crack stopping capability deteriorates
Solution Approach 1:
The first electrode is designed with spatially varying thickness: a first thickness in the region overlapping the insulating layer (providing crack stopping capability) and a second thickness in other regions (reducing overall electrode thickness). This local variation allows the electrode to be thin overall while maintaining sufficient thickness where needed for reliability.
Solution Approach 2:
Instead of varying thickness uniformly across the electrode, the invention introduces dimensional variation in the thickness direction at specific locations. The electrode transitions from a uniform thin structure to a structured thickness profile, adding a dimensional variable (thickness variation) to solve the contradiction between compactness and reliability.
2Reliability
If the first electrode strongly adheres to the base body to ensure electrical conductivity, then electrical connectivity is improved, but stress concentration worsens
Solution Approach 1:
The insulating layer is positioned at specific locations (outer periphery of the first electrode) rather than uniformly across the entire electrode structure. This localized insulation creates regions with different mechanical properties: the insulating region reduces stress concentration, while non-insulating regions maintain strong adhesion for electrical conductivity.
3Reliability
If thermal stress resistance is increased by modifying electrode structure, then reliability under thermal cycling is improved, but manufacturing complexity worsens
Solution Approach 1:
The invention modifies physical parameters of existing electrode components (thickness distribution, material composition, adhesion characteristics) rather than introducing entirely new structural elements. The first electrode's thickness parameter varies spatially, and its material composition is adjusted to control adhesion, providing thermal stress resistance through parameter optimization rather than structural complexity.
Data Source
AI summary
A ceramic substrate that includes: a base body including a ceramic layer; at least one inner conductor in the base body; a terminal electrode including a first electrode in contact with an outer surface of the base body and a second electrode covering a surface of the first electrode; and an insulating layer covering at least a portion of an outer periphery of the first electrode, the ceramic substrate including a section where the first electrode, the insulating layer, and the second electrode overlap in a thickness direction, the first electrode having a non-conductive component content of from 3% by weight to 40% by weight, the second electrode having a non-conductive component content of from 0% by weight to 10% by weight, and the non-conductive component content of the first electrode being equal to or greater than the non-conductive component content of the second electrode.