Conductive Paste Terminal Electrodes Non-Oxidizing Firing
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Solution Overview
Problem
Conductive pastes used for forming terminal electrodes in multilayer ceramic components face issues with insufficient adhesion strength and infiltration of plating solutions, leading to delamination and reduced insulation resistance, especially when fired in a non-oxidizing atmosphere.
Innovation Solution
A conductive paste comprising a glass frit with specific compositions, including 40-65% BaO, 15-23% B2O3, 2-12% Al2O3, 0.5-7% TiO2, and 3-7.5% CaO, along with copper and/or nickel as main components, which provides excellent acid resistance and prevents plating solution infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reduction-resistant glasses such as barium borate glass, barium zinc borate glass, and barium zinc borosilicate glass are employed for terminal electrodes fired in a non-oxidizing atmosphere, then the terminal electrodes can maintain stability and conductivity, but the adhesion strength to the ceramic element is insufficient and side portions are likely to delaminate
Solution Approach 1:
The patent modifies the glass composition parameters by adding specific amounts of Al2O3 (1-10 mass%) and SiO2 (1-10 mass%) to the conventional barium borate glass system. This parameter change transforms the glass structure to achieve both reduction resistance and improved adhesion strength, resolving the contradiction between stability and adhesion.
Solution Approach 2:
The patent creates a composite glass system combining barium borate glass with aluminum oxide and silica components. This composite material approach integrates the reduction resistance of barium borate glass with the adhesion-enhancing properties of Al2O3 and SiO2, simultaneously achieving both required properties.
2Ease of manufacture
If conventional glasses are used for terminal electrodes, then the terminal electrodes can be formed, but the fired film is porous and susceptible to infiltration of plating solution, causing reduced adhesion strength and insulation resistance
Solution Approach 1:
The patent adjusts the glass composition parameters by incorporating specific ranges of Al2O3 (1-10 mass%) and SiO2 (1-10 mass%) along with controlled amounts of ZnO (0-5 mass%). These parameter changes modify the glass network structure to reduce porosity while maintaining formability, preventing plating solution infiltration.
Solution Approach 2:
The modified glass composition acts as an intermediary barrier between the terminal electrode and the plating solution. The enhanced glass structure with Al2O3 and SiO2 components creates a denser, less porous film that mediates and prevents direct contact and infiltration of plating solution.
3Volume of moving object
If the terminal electrode film has small thickness, then the component size is reduced, but the adhesion strength is significantly reduced and delamination occurs
Solution Approach 1:
The patent modifies the glass composition parameters to include Al2O3 (1-10 mass%) and SiO2 (1-10 mass%) which enhance adhesion strength. This allows the terminal electrode film to maintain high adhesion even at reduced thickness, enabling miniaturization without delamination issues.
Solution Approach 2:
The patent enhances the local quality of the glass film by incorporating specific components that improve adhesion properties. This localized enhancement of adhesion quality allows thin films to maintain sufficient bonding strength to the ceramic substrate.
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 paste forms dense, acid-resistant terminal electrodes with improved adhesion strength and reliability, preventing delamination and insulation resistance reduction, even when fired in a non-oxidizing atmosphere.
Implementation Method 1
a glass frit... comprises 40-65% by mass of BaO, 15-23% by mass of B2O3, 2-12% by mass of Al2O3, 0.5-7% by mass of TiO2, and 3-7.5% by mass of CaO
Implementation Method 2
an inorganic binder such as a glass frit dispersed in a vehicle... adhesion strength between the terminal electrode film and the ceramic element
Implementation Method 3
After drying, firing is carried out at a high temperature to thereby form terminal electrodes electrically connected to the internal electrodes
Data Source
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AI summary
The present invention is a conductive paste comprising a conductive powder, a glass frit, and an organic vehicle, wherein the conductive powder comprises copper and/or nickel as a main component(s), and the glass frit is substantially free of Pb, Cd, and Bi, comprises 40 to 65% by mass of BaO, 15 to 23% by mass of B2O3, 2 to 12% by mass of Al2O3, 4 to 8% by mass of SiO2, 0 to 5% by mass of ZnO, 0.5 to 7% by mass of TiO2, 3 to 7.5% by mass of CaO, and comprises any one or more of MnO2, CuO, and CoO in the ranges of 0 to 7% by mass of MnO2, 0 to 16% by mass of CuO, and 0 to 5% by mass of CoO, in terms of oxide. According to the present invention, it is possible to provide a conductive paste that can form a dense electrode film that has excellent acid resistance and is free from insufficient strength and infiltration of a plating solution, even in the case of firing in a non-oxidizing atmosphere.