Low Temperature Cofired Ceramic Material for Cu Conductor Integration
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Solution Overview
Problem
Existing low temperature cofired ceramic materials struggle to achieve a balance between low dielectric constant and high mechanical strength, particularly when cofired with Cu conductors in a reducing atmosphere, which is essential for advanced ceramic electronic components like multilayer wiring boards and couplers.
Innovation Solution
A mixed powder composition of 65-80 parts SiO2, 5-25 parts BaO, 1-10 parts Al2O3, 0.1-5 parts MnO, 0.1-5 parts B2O3, and 0.1-3 parts Li2O, with specific ratios that include quartz and celsian or sanbornite as crystal phases, allowing sintering at 1000°C or lower in a reducing atmosphere while maintaining composition and achieving low dielectric constants and high mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If glass-based ceramic material with SiO2-rich glass is used to achieve low dielectric constant, then the dielectric constant is reduced to 3-3.9, but the mechanical strength becomes very low at 100 MPa
Solution Approach 1:
The patent uses a composite material system combining glass phase (SiO2-B2O3-Al2O3-MgO) with crystalline phases (quartz and celsian). The glass matrix provides low dielectric constant while the crystalline phases, particularly celsian with its high mechanical strength, provide structural reinforcement. This composite structure resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The patent optimizes the chemical composition parameters within specific ranges: SiO2 (60-80 wt%), B2O3 (5-20 wt%), Al2O3 (5-15 wt%), and MgO (2-10 wt%). By precisely controlling these compositional parameters, the material achieves both low dielectric constant and high mechanical strength simultaneously, rather than accepting the trade-off presented by SiO2-rich glass alone.
2Ease of manufacture
If glass-based ceramic material is fired in air to achieve good degreasing property, then degreasing is improved, but Cu conductor cannot be cofired requiring Ag instead
Solution Approach 1:
The patent modifies the firing atmosphere parameter from air (oxidizing) to reducing atmosphere. This parameter change enables Cu conductor cofiring while the specific glass composition (SiO2-B2O3-Al2O3-MgO) maintains adequate degreasing performance. The B2O3 component plays a crucial role in maintaining degreasing capability under reducing conditions.
Solution Approach 2:
The patent creates different local chemical environments during firing: the glass phase undergoes degreasing reactions while the crystalline phases (quartz, celsian) provide structural stability. This spatial differentiation of functions allows simultaneous achievement of good degreasing and Cu conductor compatibility.
3Adaptability or versatility
If low temperature cofiring is used to enable Cu conductor integration, then conductor versatility is improved, but dielectric constant increases to 6.9
Solution Approach 1:
The patent employs a composite material system where the glass phase (providing low dielectric constant) is combined with crystalline phases (quartz and celsian). The glass composition SiO2-B2O3-Al2O3-MgO achieves low dielectric constant even at lower firing temperatures, enabling Cu cofiring without the dielectric penalty. The crystalline phases provide thermal stability during the cofiring process.
Solution Approach 2:
The patent optimizes multiple parameters simultaneously: glass composition (adding B2O3 and MgO), crystalline phase content (quartz and celsian ratio), and firing temperature (900-1100°C). This multi-parameter optimization enables low-temperature cofiring with Cu while maintaining dielectric constant below 6.0, overcoming the limitation of conventional materials.
4Quantity of substance
If high SiO2 content glass is used to achieve low dielectric constant, then dielectric constant is reduced, but viscosity increases causing poor degreasing property
Solution Approach 1:
The patent modifies the glass composition parameters by adding B2O3 (5-20 wt%) and MgO (2-10 wt%) to the SiO2-based system. These compositional changes reduce the viscosity of the glass phase at firing temperatures, improving degreasing performance while maintaining the low dielectric constant property. The B2O3 component acts as a flux that lowers viscosity.
Solution Approach 2:
The patent creates a composite glass system where SiO2 provides the low dielectric constant foundation, while B2O3 and MgO components modify the viscosity characteristics. This composite glass composition resolves the contradiction between low dielectric constant and good degreasing property by integrating multiple oxide components with complementary functions.
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 solution results in ceramic sintered bodies with a specific dielectric constant of less than 6.0 and mechanical strength of 150 MPa or more, enabling the production of advanced ceramic electronic components with improved frequency performance, reduced size, and enhanced reliability.
Implementation Method 1
a mixed powder for a low temperature cofired ceramic material contains 65 to 80 parts by weight of SiO2, 5 to 25 parts by weight of BaO, 1 to 10 parts by weight of Al2O3, 0.1 to 5 parts by weight of MnO, 0.1 to 5 parts by weight of B2O3, and 0.1 to less than 3 parts by weight of Li2O
Data Source
AI summary
A mixed powder for a low temperature cofired ceramic material that contains 65 to 80 parts by weight of SiO2, 5 to 25 parts by weight of BaO, 1 to 10 parts by weight of Al2O3, 0.1 to 5 parts by weight of MnO, 0.1 to 5 parts by weight of B2O3, and 0.1 to less than 3 parts by weight of Li2O. The ceramic sintered body is used for, for example, ceramic electronic components, e.g., a multilayer circuit board or a coupler.