Resistive Paste for Monolithic Ceramic Capacitors
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Solution Overview
Problem
Monolithic ceramic capacitors used for decoupling near CPUs can experience oscillations due to parallel resonance and increased impedance due to low equivalent series resistance (ESR), requiring controlled ESR levels, which is challenging with existing resistive electrode materials that can lead to blister formation and variability in resistance values based on ceramic laminate dimensions and layer configurations.
Innovation Solution
A resistive paste containing an In-Sn complex oxide, glass frit, and organic vehicle, with specific metal and oxide additives that promote or prevent densification, allowing for controlled ESR levels by adjusting the component ratios of densification promoting metals (Ni, Cu) and preventing metals (Mo, Cr, Nb) or oxides (Al2O3, TiO2, ZrO2, ZnO2) to form a stable resistive electrode layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ag, Al2O3, or ZrO2 is substituted for ITO to increase resistance, then the resistance of the resistive electrode layer increases, but blisters occur due to over-sintering or denseness is reduced due to insufficient sintering
Solution Approach 1:
The patent changes the chemical composition parameters of the resistive electrode layer by introducing specific metal oxides (Bi2O3, PbO, ZnO) and controlling the substitution rates of Ag, Al2O3, and ZrO2 for ITO. This allows precise adjustment of both resistance and sintering behavior to prevent blisters while maintaining desired resistance values
Solution Approach 2:
The patent creates a composite resistive electrode layer containing multiple metal oxides (ITO, Bi2O3, PbO, ZnO, Ag, Al2O3, ZrO2) with specific compositional ratios. This composite approach enables simultaneous control of resistance, sintering characteristics, and defect prevention that cannot be achieved with single-material substitutions
2Reliability
If the substitution rate of Ag, Al2O3, or ZrO2 is increased to increase resistance, then the resistance increases, but over-sintering or insufficient sintering occurs
Solution Approach 1:
The patent introduces Bi2O3 and PbO as additional substitution components for ITO, creating a multi-parameter compositional system. This allows independent optimization of resistance (through Ag, Al2O3, ZrO2 substitution) and sintering control (through Bi2O3, PbO, ZnO addition), resolving the conflict between resistance control and sintering precision
Solution Approach 2:
The patent uses Bi2O3, PbO, and ZnO as intermediary substances that mediate between the resistance-increasing effect of Ag/Al2O3/ZrO2 substitution and the sintering process. These intermediaries facilitate proper densification and grain growth while allowing the resistive components to function effectively
3Ease of manufacture
If a single resistive paste composition is used, then manufacturing is simplified, but ESR varies with ceramic laminate dimensions and layer configuration
Solution Approach 1:
The patent establishes specific compositional parameter ranges for the resistive paste, including the total substitution rate of Ag/Al2O3/ZrO2 for ITO and the addition amounts of Bi2O3, PbO, and ZnO. These parameter specifications ensure consistent ESR values across different ceramic laminate dimensions and configurations while maintaining manufacturability
Solution Approach 2:
The patent optimizes the local composition of the resistive electrode layer by controlling the distribution and ratios of different metal oxides. This ensures that the electrode layer has appropriate resistance and sintering characteristics regardless of the overall size or layer structure of the ceramic capacitor
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 enables precise control of ESR in monolithic ceramic capacitors, preventing blister formation and ensuring high reliability and moisture resistance, while allowing for flexible resistance tuning by mixing low- and high-resistance paste compositions.
Implementation Method 1
an In-Sn complex oxide, which includes In2O3 and SnO2
Implementation Method 2
a glass frit, and an organic vehicle... a sintered compact formed by firing the resistive paste
Data Source
Figure 1~2
Figure 3(a)~4
Figure 5~6
AI summary
The formation of a resistive electrode layer as a portion of an external electrode of a monolithic ceramic capacitor by baking a resistive paste, which contains ITO, a glass frit, and an organic vehicle, to impart the function of a resistance element to the external electrode may lead to the occurrence of blisters or reduced denseness. The resistive paste further contains a densification promoting metal, which promotes densification of a sintered compact of the resistive paste and is at least one selected from the group consisting of Ni and Cu, and a densification preventing metal, which prevents the densification and is at least one selected from the group consisting of Mo, Cr, and Nb. Preferably, the component ratio (ITO, Mp, Mc) (percent by volume) of ITO, the densification promoting metal (Mp), and the densification preventing metal (Mc) is in a range defined by points ABCDE in Fig. 5.