Multilayer Ceramic Substrate Shrinkage Control via Glass Ceramic Layers
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Solution Overview
Problem
Multilayer ceramic substrates manufactured using low temperature cofired ceramic materials face issues with low flexural strength and electrode bonding strength due to constraining layers sucking glass components from the laminate during firing, leading to compressive stress deficiencies and increased warping.
Innovation Solution
Incorporating a laminate structure with internal electrodes and glass ceramic layers, where the glass ceramic layers are strategically positioned within 100 μm of the principal surfaces to supply sufficient glass components, reducing thermal expansion coefficients and enhancing compressive stress, thereby increasing flexural strength and electrode bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If constraining layers are inserted between ceramic layers to suppress shrinkage in the planar direction, then shrinkage control is improved, but the amount of warp increases and flexural strength decreases
Solution Approach 1:
The patent removes the constraining layers from the final substrate structure, eliminating the source of differential shrinkage behavior. By extracting these problematic layers, the substrate achieves uniform shrinkage characteristics and improved flexural strength while maintaining adequate shrinkage control through the low temperature cofired ceramic material composition itself
Solution Approach 2:
The patent creates a homogeneous substrate structure by using only low temperature cofired ceramic layers without interspersed constraining layers. This uniform composition ensures consistent shrinkage behavior throughout the substrate thickness, reducing warp and improving overall structural integrity and flexural strength
2Manufacturing precision
If constraining layers are used to suppress shrinkage, then shrinkage control is improved, but electrode bonding strength between substrate and surface electrode decreases
Solution Approach 1:
The patent removes constraining layers that create interfaces disrupting electrode bonding. By eliminating these intermediate layers, the surface electrodes achieve direct bonding to the low temperature cofired ceramic substrate, significantly improving bonding strength while shrinkage control is maintained through material composition optimization
3Manufacturing precision
If constraining layers are inserted to form a laminate structure, then shrinkage in the planar direction is suppressed, but the substrate exhibits large warp and low flexural strength
Solution Approach 1:
The patent achieves a homogeneous laminate structure composed entirely of low temperature cofired ceramic layers with matching thermal and mechanical properties. This uniformity ensures synchronized shrinkage behavior during firing, preventing differential stress that causes warp, while maintaining effective shrinkage suppression through the optimized ceramic material composition
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 approach results in a multilayer ceramic substrate with improved flexural strength and electrode bonding strength, reducing the likelihood of cracks and maintaining high insulation resistance while maintaining low production costs.
Implementation Method 1
a glass ceramic layer 3a, 3b in which an entire thickness or a part of a thickness of the glass ceramic layer 3a, 3b exists within 100 μm inside of the laminate 1 as measured from a principal surface of the laminate 1
Data Source
AI summary
A multilayer ceramic substrate that includes a laminate having stacked ceramic layers formed of a ceramic material containing a main component, containing 48 to 75% by weight of Si, 20 to 40% by weight of Ba, and 10 to 40% by weight of Al, and an auxiliary component containing at least 2.5 to 20 parts by weight of Mn with respect to 100 parts by weight of the main component, and in the laminate, glass ceramic layers in which the entire or a portion of the thickness thereof exists within 100 μm inside of the laminate as measured from opposed principal surfaces are further stacked.