Sr Anorthite Ceramic Substrate for High-Frequency Applications
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ceramic substrates face challenges in achieving strong bonding between layers with different dielectric constants without using boron, which can cause delamination, cracking, and reduce the Q value, especially when forming high-frequency parts that require low resistance wiring and low dielectric constant layers.
Innovation Solution
The use of cordierite for a low dielectric constant layer and Sr anorthite as a common crystal phase in a ceramic substrate, allowing for reduced boron content and strong bonding between layers with different dielectric constants, while maintaining high Q values and controlling dielectric constants effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If B2O3 is used as a component to form common crystal phase (Mg,Ti)2(BO3)O for strong bonding between ceramic layers, then bonding strength is improved, but Q value decreases
Solution Approach 1:
The patent changes the chemical composition parameters by replacing B2O3 with SrO and TiO2 to form Sr anorthite phase instead of (Mg,Ti)2(BO3)O. This parameter change allows achieving strong bonding between ceramic layers with different dielectric constants while maintaining high Q values, as Sr anorthite provides both bonding strength and low dielectric loss characteristics.
Solution Approach 2:
The patent discards B2O3 as a component and recovers the bonding function through Sr anorthite phase formation. By eliminating B2O3 which causes Q value degradation while preserving the essential bonding capability through the common Sr anorthite crystal phase, the invention resolves the contradiction between bonding strength and energy loss.
2Adaptability or versatility
If dielectric ceramics with significantly different compositions are used to form layers with different dielectric constants, then dielectric characteristics are improved, but delamination and cracking occur due to thermal expansion mismatch
Solution Approach 1:
The patent applies homogeneity by forming a common Sr anorthite crystal phase in both ceramic layers with different dielectric constants. This common phase ensures matched thermal expansion coefficients and contraction behaviors during firing, preventing delamination and cracking while allowing the layers to maintain their different dielectric characteristics through other compositional elements.
Solution Approach 2:
The patent uses composite material strategy by combining Sr anorthite phase with different dielectric ceramic compositions (such as Al2O3-based and cordierite-based ceramics) in each layer. The Sr anorthite acts as a bonding matrix that unifies the thermal properties, while the different composite compositions provide the required different dielectric constants for various functional layers.
3Loss of energy
If low melting point metals such as Cu, Ag, and Au are used as electrode materials for low resistance wiring, then electrical resistance is improved, but sintering temperature must be reduced to about 800 to 1,000° C.
Solution Approach 1:
The patent changes the sintering temperature parameter to the range of 800 to 1,000°C, which is compatible with low melting point metals like Cu, Ag, and Au. This temperature reduction is achieved by using Sr anorthite-based dielectric ceramics that can be sintered at lower temperatures while maintaining strong bonding and low dielectric loss, enabling the use of low-resistance metal electrodes.
4Quantity of substance
If dielectric ceramics with higher dielectric constant are used to form capacitors, then capacitance is improved, but high frequency signal transmission is delayed and crosstalk increases
Solution Approach 1:
The patent applies local quality by using dielectric ceramics with different dielectric constants in different local regions of the ceramic substrate. High dielectric constant ceramics are used locally in capacitor regions to achieve high capacitance, while low dielectric constant ceramics are used in transmission line regions to ensure fast signal transmission and low crosstalk, with Sr anorthite phase providing unified bonding characteristics.
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 results in a ceramic substrate with strong bonding between layers, reduced delamination and cracking, and improved dielectric characteristics, enabling the use of low melting point metals for wiring and maintaining high Q values, suitable for high-frequency applications.
Implementation Method 1
both including Sr anorthite as a common crystal phase
Implementation Method 2
whose thermal expansion coefficients are close to each other
Implementation Method 3
a second ceramic layer including Sr anorthite and cordierite and having a dielectric constant lower than that of the first ceramic layer
Implementation Method 4
Al2O3 or an oxide dielectric with a dielectric constant higher than that of Al2O3
Implementation Method 5
firing the laminate to form Sr anorthite
Data Source
AI summary
A ceramic substrate and a method for production thereof are provided, in which the ceramic substrate includes a composite of: a first ceramic layer including Sr anorthite and Al2O3 or an oxide dielectric with a dielectric constant higher than that of Al2O3; and a second ceramic layer including Sr anorthite and cordierite and having a dielectric constant lower than that of the first ceramic layer.