Multilayer Ceramic Substrate Shrinkage Control via Segmented Protective Layer
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Solution Overview
Problem
Multilayer ceramic substrates with glass components on the surface experience reduced mechanical strength due to dimensional shrinkage and chemical solution exposure, leading to compromised surface integrity.
Innovation Solution
A multilayer ceramic substrate design incorporating low-temperature co-fired ceramic base layers, constraint layers with unsintered metal oxides, and a protective layer with varying metal oxide content and thermal expansion coefficients to minimize planar shrinkage and enhance surface mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glass components are contained in the second sheet layers given to principal surfaces to suppress planar shrinkage, then dimensional accuracy is improved, but mechanical strength of the surface is reduced due to dissolution in chemical solutions
Solution Approach 1:
The protective layer is divided into two distinct layers: a first protective layer containing glass components for suppressing planar shrinkage and maintaining dimensional accuracy, and a second protective layer containing ceramic powder and lacking glass components for providing high mechanical strength and chemical resistance. This segmentation allows each layer to perform its specific function without compromise.
Solution Approach 2:
Different regions of the protective layer are assigned different compositions and functions. The first protective layer (inner layer) has glass components for shrinkage control, while the second protective layer (outer layer) has ceramic powder for strength and chemical resistance. This local differentiation of material properties resolves the contradiction between dimensional accuracy and surface strength.
2Stability of the object's composition
If glass components are used in the protective layer to control shrinkage, then planar shrinkage is reduced, but the surface becomes vulnerable to chemical solution attack
Solution Approach 1:
The first protective layer containing glass components acts as an intermediary that controls shrinkage during firing, while the second protective layer containing ceramic powder serves as a protective barrier against chemical solutions. The two layers work together where the inner layer manages dimensional stability and the outer layer provides chemical resistance.
Solution Approach 2:
The protective layer is constructed as a composite structure with two different material compositions: an inner layer with glass components for shrinkage control and an outer layer with ceramic powder for chemical resistance. This composite approach allows the system to simultaneously achieve shrinkage control and chemical resistance.
3Stability of the object's composition
If the protective layer contains glass component for shrinkage control, then dimensional stability is improved, but chemical resistance deteriorates
Solution Approach 1:
The protective function is segmented into two layers: the first layer handles dimensional stability through glass components, while the second layer handles chemical resistance through ceramic powder. This functional segmentation resolves the contradiction by assigning each property to the appropriate layer.
Solution Approach 2:
The outer surface region (second protective layer) is given ceramic powder composition for chemical resistance, while the inner region (first protective layer) contains glass components for shrinkage control. This local quality differentiation ensures both dimensional stability and chemical resistance are achieved in their respective required locations.
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 design reduces planar shrinkage, increases dimensional accuracy, and significantly enhances the mechanical strength of the substrate's surface, while maintaining chemical resistance and high-frequency characteristics.
Implementation Method 1
a plurality of first constraint layers which contain a metal oxide not completely sintered at the sintering temperature of the low-temperature co-fired ceramic material and which are placed between the base layers
Implementation Method 2
the content of the metal oxide in a surface section of the protective layer is higher than the content of the metal oxide in a boundary section of the protective layer that is in contact with the outermost base layers... the reduction of mechanical strength due to the dissolution of the glass component contained in a surface of the multilayer ceramic substrate can be prevented
Data Source
AI summary
A multilayer ceramic substrate according to the present invention includes a plurality of base layers that are laminated containing a low-temperature co-fired ceramic material, a plurality of first constraint layers which contain a metal oxide not completely sintered at the sintering temperature of the low-temperature co-fired ceramic material and which are located between the base layers, and a protective layer which contains the metal oxide and which is in contact with an outermost base layer of the plurality of base layers in the lamination direction, and wherein X1>X2, where X1 is a content of the metal oxide in a surface section of the protective layer and X2 is a content of the metal oxide in a boundary section of the protective layer that is in contact with the outermost base layer.