Conductive Paste Glass Composition for Multilayer Ceramic Capacitor Electrodes
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Solution Overview
Problem
Conductive pastes used for forming external electrodes in multilayer ceramic capacitors face issues with ZnO elution during plating, leading to decreased flexure strength and defective plating due to glass flotation and poor densification, which affects plating resistance and ceramic integrity.
Innovation Solution
A conductive paste with a glass composition containing BaO, SrO, CaO, B2O3, and SiO2, Al2O3, or TiO2, where BaO and CaO inhibit reactions with the ceramic, and a molar ratio of B2O3/(SiO2+Al2O3+TiO2) between 0.7 and 1.5 improves densification and plating resistance, while omitting ZnO prevents elution into plating solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high ZnO content is used in the glass frit to improve densification, then the densification of external electrodes is improved, but ZnO is eluted into plating solution causing decreased flexure strength and defective plating
Solution Approach 1:
The patent removes ZnO from the glass frit composition entirely, extracting the harmful element that causes elution into plating solution. The glass frit is reformulated to contain only BaO, SrO, ZnO (replaced with other oxides), B2O3, and SiO2, eliminating the source of ZnO contamination while maintaining densification through alternative glass composition ratios.
Solution Approach 2:
The patent changes the chemical composition parameters of the glass frit by eliminating ZnO and adjusting the ratios of remaining oxides. Specifically, BaO is set at 10-50 wt%, SrO at 5-40 wt%, B2O3 at 15-30 wt%, and SiO2 at 3-20 wt%, with the sum of B2O3 and SiO2 comprising 40-80 wt% of the total glass frit, creating a new compositional parameter set that achieves densification without ZnO elution.
2Reliability
If inappropriate proportions of SiO2 and B2O3 are used in the glass frit, then the plating resistance and glass flotation control are compromised, but achieving balance among plating resistance, glass flotation suppression, and densification is difficult
Solution Approach 1:
The patent establishes specific parameter ranges for SiO2 (3-20 wt%) and B2O3 (15-30 wt%) with their combined content comprising 40-80 wt% of the total glass frit. These parameter changes create an optimized composition space that simultaneously achieves good plating resistance, suppresses glass flotation, and maintains densification without requiring complex multi-parameter optimization.
Solution Approach 2:
The patent creates a composite glass frit material combining multiple oxides (BaO, SrO, B2O3, SiO2) in specific proportions. This composite approach leverages the complementary properties of each oxide: BaO and SrO for basic glass formation and wetting, B2O3 for low melting point and fluxing, and SiO2 for structural framework and chemical stability, achieving balanced performance across multiple properties.
3Manufacturing precision
If glass component reacts with ceramic body due to inappropriate composition, then reaction layer forms causing crack generation and degraded flexure strength
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass frit by selecting oxides with appropriate chemical stability characteristics. The use of BaO (10-50 wt%), SrO (5-40 wt%), and controlled B2O3 (15-30 wt%) and SiO2 (3-20 wt%) creates a glass composition that forms a stable interface with the ceramic body, preventing harmful reactions while maintaining adhesion.
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 enhances plating resistance, suppresses glass flotation, and improves the densification of external electrodes, resulting in a highly reliable multilayer ceramic electronic component with improved flexure strength and reduced risk of cracks.
Implementation Method 1
the formation of external electrodes with the use of the conductive paste is supposed to make the glass frit less likely to penetrate into the ceramic constituting the ceramic laminate during firing
Implementation Method 2
making the glass frit less likely to penetrate into the ceramic constituting the ceramic laminate during firing
Implementation Method 3
the proportions of the SiO2 and B2O3 constituting the glass frit affect not only the plating resistance (plating solution resistance) of external electrodes formed, but also glass flotation of the glass component floated on the surfaces of the external electrodes and the densification of the external electrodes
Implementation Method 4
BaO: 10 to 50 weight %, SrO: 5 to 40 weight %
Implementation Method 5
causing ingress of the plating solution from voids after the ZnO elution into the ceramic body constituting the multilayer ceramic capacitor
Data Source
AI summary
A conductive paste for forming external electrodes for a multilayer ceramic electronic component. The paste contains a glass composition containing (a) BaO, (b) at least one of SrO and CaO, (c) ZnO, (d) B2O3, and (e) at least one selected from the group consisting of SiO2, Al2O3, and TiO2, in which the total content percentage of BaO, SrO, and CaO is 30 mol % or more, the molar ratio represented by B2O3/(SiO2+Al2O3+TiO2) is 0.7 to 1.5, and the content percentage of ZnO is 0 to 5 mol %.