Ceramic Electrode Interface Using Al-B Oxides for Moisture Resistance
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Solution Overview
Problem
Conventional ceramic electronic devices face challenges in bonding external electrodes with low ionization tendency conductors, such as copper, to the element body or glass frit, resulting in poor moisture resistance and bonding strength.
Innovation Solution
Incorporating an interface part at the boundary between the external electrode and the ceramic layer, comprising oxides containing aluminium and boron, which vitrifies and enhances bonding through a mixing structure, improving both moisture resistance and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a baked electrode containing copper or silver is used as the external electrode, then the conductivity is improved, but the bonding strength to the element body deteriorates
Solution Approach 1:
The patent introduces a specific oxide composition (containing Al2O3, SiO2, and B2O3 in defined ratios) as an intermediary layer between the copper/silver external electrode and the ceramic element body. This intermediary oxide layer facilitates bonding by creating a transition zone that is chemically compatible with both the metal electrode and the ceramic substrate, resolving the contradiction between maintaining electrode conductivity and achieving strong bonding.
Solution Approach 2:
The patent creates a composite structure at the electrode-element body interface by combining multiple oxides (Al2O3, SiO2, B2O3) in specific proportions. This composite oxide material exhibits properties that bridge the gap between metallic conductors and ceramic insulators, enabling both electrical conductivity and mechanical bonding strength to be achieved simultaneously.
2Ease of manufacture
If a baked electrode is formed by applying conductive paste containing conductor powder and glass frit, then the ease of manufacture is improved, but the moisture resistance deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass frit by specifying precise ratios of Al2O3 (40-70 wt%), SiO2 (20-50 wt%), and B2O3 (5-20 wt%). By changing these compositional parameters within defined ranges, the patent achieves both ease of manufacture through conventional paste application and improved moisture resistance through optimized chemical properties that reduce moisture penetration and degradation.
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 use of an interface part with a specific composition of aluminium and boron oxides allows for high moisture resistance and bonding strength, even with conductors like copper, as evidenced by reduced failures in pressure cooker bias and thermal shock tests.
Implementation Method 1
the oxide containing boron vitrifies under a wide range of conditions. Because the interface part can flow at a low temperature due to the action of the oxide containing boron, namely glass
Implementation Method 2
The baked electrode can be formed by applying a conductive paste containing conductor powder and glass frit to the surface of the element body and baking the paste
Data Source
AI summary
A ceramic electronic device comprises an element body including a ceramic layer and an internal electrode layer, and an external electrode electrically connected to at least one end of the internal electrode layer. The element body includes an interface part at least at a part of a boundary between the external electrode and the ceramic layer. The interface part includes an oxide containing aluminium and an oxide containing boron.