Ceramic Multilayer Substrate Phosphorus Gradient Shrinkage Control
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Solution Overview
Problem
The existing ceramic multilayer substrates face issues with peeling and breakage of internal conductors due to mismatched shrinkage stresses between first and second ceramic green layers during the firing process, where the electrically conductive paste film experiences stress from both layers in different directions.
Innovation Solution
A ceramic multilayer substrate is designed with a first ceramic layer sintered using a material with a phosphorus component, where the unsintered second ceramic material with a higher sintering temperature is laminated and fixed by permeation of the first ceramic material, and the phosphorus component diffuses to restrict shrinkage, reducing stress on the electrically conductive paste film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two types of unfired ceramic layers with different sintering temperatures are laminated to restrict shrinkage, then shrinkage control is improved, but peeling and breakage of internal conductors occur due to mismatched shrinkage stresses
Solution Approach 1:
The patent applies different phosphorus concentrations at different locations within the first ceramic layer. The phosphorus concentration is higher near the interface with the second ceramic layer and decreases toward the outer surface, creating a gradient structure. This local variation in composition allows the first ceramic layer to better match the shrinkage behavior of the second ceramic layer locally, reducing stress concentration at the interface and preventing conductor peeling and breakage while maintaining overall shrinkage control.
Solution Approach 2:
The patent changes the chemical composition parameter by introducing a phosphorus concentration gradient in the first ceramic layer. By controlling the phosphorus content to decrease from the interface toward the outer surface, the sintering characteristics and shrinkage behavior of the first ceramic layer are modified to better compatibility with the second ceramic layer, thereby reducing differential shrinkage stress and improving conductor reliability.
2Reliability
If phosphorus component is added to restrict shrinkage stress, then internal conductor reliability is improved, but substrate property deterioration may occur
Solution Approach 1:
Instead of uniformly distributing phosphorus throughout the first ceramic layer, the patent creates a localized concentration gradient where phosphorus is concentrated near the interface with the second ceramic layer and decreases toward the outer surface. This localized approach provides shrinkage stress relief where most needed at the interface while minimizing phosphorus content in regions where it could cause substrate property deterioration, thus balancing conductor reliability with substrate quality.
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 approach reduces the occurrence of peeling and breakage of internal conductors by relaxing shrinkage stress and minimizing substrate property deterioration, allowing for the production of ceramic multilayer substrates with improved reliability and high dimensional accuracy.
Implementation Method 1
the phosphorus component diffuses from the first ceramic layer into the second ceramic layer to restrict shrinkage of the unsintered second ceramic material
Implementation Method 2
the unsintered second ceramic material is fixed by a part of the first ceramic material which permeates from the first ceramic layer into the second ceramic layer
Implementation Method 3
a first ceramic layer formed by sintering a first ceramic material, a second ceramic layer which is laminated so as to come into contact with a principal surface of the above-described first ceramic layer and which contains an unsintered second ceramic material having a sintering temperature higher than the sintering temperature of the above-described first ceramic material
Data Source
AI summary
A ceramic multilayer substrate exhibiting reduced pealing and breakage of an internal conductor disposed between a ceramic layer serving as a base member and a ceramic layer for restricting shrinkage includes a first ceramic layer 11, a second ceramic layer 12 laminated so as to come into contact with a principal surface of the first ceramic layer 11, and an internal conductor 13 disposed between the first ceramic layer 11 and the second ceramic layer 12, a phosphorus component layer 16a is disposed in the first ceramic layer 11 with a concentration gradient in which the concentration decreases in a direction away from the internal conductor 13.