LTCC Substrate Composition for Low Loss and Silver Migration Control
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Solution Overview
Problem
Low temperature co-fired ceramic (LTCC) substrates face challenges in minimizing signal attenuation and maintaining stability with silver electrodes during co-firing, leading to potential warpage and silver migration issues, which are not adequately addressed by existing compositions.
Innovation Solution
A substrate composition comprising 83-91 wt% CaO-B2O3-SiO2 glass powder, 7.5-14 wt% SiO2 powder with specific particle diameter distributions, and 1.5-3 wt% β-wollastonite powder, which suppresses silver migration and warpage while maintaining low relative permittivity and high Q value, ensuring effective signal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LTCC substrate materials are used, then the substrate can be manufactured, but signal attenuation increases due to high dielectric loss at millimeter wave frequencies
Solution Approach 1:
The patent changes the chemical composition parameters of the glass material by incorporating specific metal oxides (Bi2O3 at 10-30 wt%, ZnO at 5-20 wt%, B2O3 at 10-30 wt%) to achieve low dielectric loss at millimeter wave frequencies while maintaining manufacturability
Solution Approach 2:
The patent creates a composite glass material system combining multiple oxide components (Bi2O3, ZnO, B2O3, SiO2, Al2O3) to achieve synergistic effects that reduce dielectric loss and improve signal propagation characteristics at high frequencies
2Reliability
If the substrate material is designed for low dielectric loss, then signal propagation improves, but manufacturing complexity increases due to precise composition control requirements
Solution Approach 1:
The patent establishes specific parameter ranges for each oxide component (e.g., Bi2O3: 10-30 wt%, ZnO: 5-20 wt%) that balance performance requirements with manufacturing feasibility, allowing controlled variation while maintaining quality
3Reliability
If silver electrode is used for conductivity, then electrical performance improves, but silver migration and warpage occur during co-firing process
Solution Approach 1:
The glass material acts as an intermediary between the silver electrode and the ceramic substrate, with its specific chemical composition (Bi2O3, ZnO, B2O3) suppressing silver ion migration and reducing thermal expansion mismatch during co-firing
Solution Approach 2:
The patent adjusts the chemical composition parameters of the glass to optimize its interaction with silver electrodes, specifically controlling oxidation-reduction properties and thermal expansion characteristics to prevent silver migration and warpage
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 composition achieves a relative permittivity of 6.0 or less and a Q value of 500 or more at 2.5 GHz, along with a reflectance ratio R420/R800 of 85% or more, preventing silver electrode deterioration and ensuring stable substrate performance.
Implementation Method 1
The LTCC substrate is formed by simultaneously burning a ceramic carrier structure, a conductive resistor and a dielectric material in a furnace of less than 1000°C
Implementation Method 2
1.5 to 3 wt% of β-wollastonite (CaSiO3) powder
Data Source
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AI summary
It is demanded that a LTCC substrate composition capable of maintaining low relative permittivity k and high Q value without having a reactivity with a silver which is an electrode material and causing migration of the silver during a co-firing operation at a low temperature. Provided with a low temperature co-fired substrate composition containing 83 to 91 wt.% of CaO-B2O3-SiO2 based glass powder, 7.5 to 14 wt.% of two or more kinds of nanometer-sized SiO2 powders having different ranges of particle diameter and 1.5 to 3 wt.% of β-wollastonite powder as a crystallization agent wherein the glass powder contains 40.0 to 45.0 wt.% of CaO, 9.0 to 20.0 wt.% of B2O3 and 40.0 to 46.0 wt.% of SiO2.