Ceramic Multilayer Substrate Stacking for Low Sintering Shrinkage
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Solution Overview
Problem
Conventional methods for producing ceramic multilayer substrates face issues with sintering shrinkage, leading to stress, cracks, and deformation of integrated redistribution traces, which are exacerbated by uneven shrinkage in different spatial directions, and require additional laborious post-sintering processing to remove enriched sintering aids.
Innovation Solution
A method involving alternating stacking sequences of green sheets with varying sintering aid concentrations, where first green sheets with lower sintering aid content are used as terminating layers, reducing overall sintering shrinkage and enhancing the ceramic main body's robustness by diffusing sintering aids into these sheets, thereby minimizing crack formation and maintaining trace integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional green sheet stacking methods are used to produce ceramic multilayer substrates, then the substrate can be manufactured, but great sintering shrinkage occurs causing stresses and cracks in the ceramic main body
Solution Approach 1:
The patent applies local quality by using first green sheets with lower sintering aid content in specific locations (terminating layers) while using second green sheets with higher sintering aid content in other locations (inner layers). This spatial variation in sintering aid concentration creates different sintering shrinkage characteristics in different regions, where the terminating layers with lower shrinkage compensate for the higher shrinkage in inner layers, thereby reducing overall stress and crack formation in the ceramic main body.
2Manufacturing precision
If green sheets with high sintering aid content are used to ensure proper sintering, then the ceramic main body forms correctly, but sintering shrinkage becomes too great causing deformation of integrated redistribution traces
Solution Approach 1:
The patent uses local quality by strategically placing first green sheets with lower sintering aid content at the terminating layers, which have lower sintering shrinkage, while using second green sheets with higher sintering aid content in the inner layers that require more shrinkage for proper formation. This local differentiation ensures that each region undergoes the appropriate amount of shrinkage for its specific function, preserving the integrity of integrated redistribution traces while still achieving proper ceramic main body formation.
3Ease of manufacture
If uniform sintering aid distribution is used throughout the green sheet stack, then the manufacturing process is simple, but uneven shrinkage in different spatial directions occurs leading to stresses and cracks
Solution Approach 1:
The patent implements local quality by creating distinct regions with different sintering aid concentrations within the green sheet stack. First green sheets with lower sintering aid content are placed in terminating layers, while second green sheets with higher sintering aid content are placed in inner layers. This deliberate non-uniform distribution allows different spatial directions to exhibit different shrinkage characteristics, compensating for anisotropic shrinkage tendencies and preventing stress concentration that would lead to cracks.
4Reliability
If additional post-sintering processing is applied to remove enriched sintering aids, then the substrate quality improves, but the manufacturing process becomes more complex and laborious
Solution Approach 1:
The patent applies preliminary action by pre-configuring the green sheet stack with alternating layers of first and second green sheets having different sintering aid contents before the sintering process. This preliminary arrangement ensures that during sintering, the sintering aids diffuse in a controlled manner from the inner layers to the terminating layers, naturally creating the desired concentration gradient without requiring subsequent removal processing. The sintering process itself becomes the mechanism for achieving the quality improvement.
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 method achieves a sintering shrinkage of less than 16% in all spatial directions, ensuring reliable operation and robustness of the ceramic substrate with integrated redistribution traces, while reducing the risk of deformation and crack formation, and maintaining reliable component operation.
Implementation Method 1
diffusing sintering aids into these sheets
Implementation Method 2
sintering shrinkage that occurs during the sintering of the green sheet stack
Data Source
AI summary
In an embodiment a substrate includes a ceramic main body including first volume regions and second volume regions, each of the first volume regions and the second volume regions containing a ceramic material, wherein the first volume regions contain less sintering aid than the second volume regions, and wherein some of the first volume regions terminate the substrate in a stacking direction.