Multi-Layer Ceramic Capacitor Silicate Boundary Cracks
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Solution Overview
Problem
The manufacturing of multi-layer ceramic capacitors faces challenges in precisely aligning adjacent internal electrodes, leading to insufficient capacitance and increased likelihood of cracking due to thermal expansion coefficient differences and hetero-phase regions, which compromises the strength and durability of the capacitors.
Innovation Solution
Forming silicate crystals made of oxides including Ba and Si or Ti and Si in the boundary portions between the laminated block and ceramic bodies, achieved by adding BaTiO3 to the internal electrode paste and using a dielectric material with higher glass content, enhances adhesion and prevents cracking during high-temperature applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high pressure is applied to pressure-bond the laminated block, then the adhesion between layers is improved, but the ceramic bodies formed only by coating have different properties from the laminated block, resulting in lower strength and durability
Solution Approach 1:
The invention changes the formation method of ceramic bodies from simple coating to pressure bonding at the same pressure as the laminated block. This parameter change ensures that ceramic bodies and laminated block have consistent properties, eliminating the strength and durability problems caused by property differences.
Solution Approach 2:
The invention makes the formation process of ceramic bodies homogeneous with the laminated block by using the same pressure bonding method. This ensures uniform properties throughout the structure, preventing the heterogeneity that leads to cracking and reliability issues.
2Ease of manufacture
If ceramic bodies are formed only by coating to both side surfaces of the laminated block, then the manufacturing process is simplified, but the ceramic bodies have different properties from the laminated block, causing stress generation under thermal expansion
Solution Approach 1:
The invention changes the formation method of ceramic bodies from coating to pressure bonding. Although this adds a step to the manufacturing process, it ensures that ceramic bodies and laminated block have consistent thermal expansion properties, eliminating stress generation during thermal cycling.
3Reliability
If hetero-phase regions are formed in end portions of the internal electrode layer, then deterioration of insulation resistance is suppressed, but cracks still occur after firing due to the nature of hetero-phase domains
Solution Approach 1:
The invention changes the formation method of ceramic bodies from coating to pressure bonding at the same pressure as the laminated block. This eliminates the property differences between ceramic bodies and laminated block, preventing crack generation while maintaining the insulation resistance benefits of hetero-phase regions.
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 formation of silicate crystals improves the adhesion between the laminated block and ceramic bodies, effectively preventing cracks and maintaining capacitor integrity under thermal stress, thereby enhancing the strength and durability of multi-layer ceramic capacitors.
Implementation Method 1
a silicate crystal made of an oxide including Ba and Si or a silicate crystal made of an oxide including Ti and Si is formed in a boundary portion between the laminated block and the ceramic body
Implementation Method 2
when the multi-layer ceramic capacitor is attached to a substrate by reflow soldering under a high temperature atmosphere, for example, stress is generated because of a difference in the thermal expansion coefficient between the metal that forms the internal electrodes and the ceramic bodies
Data Source
AI summary
An object of the present invention is to provide a multi-layer ceramic capacitor that includes a laminated block 4 formed by laminating ceramic dielectric layers 2 and internal electrodes 3 alternately, a pair of cover layers 5 laminated on top and bottom of the laminated block, a ceramic body 6 formed on both side surfaces of the laminated block 4, and a pair of external electrodes 7 electrically connected to the internal electrodes 3 and that can effectively prevent an occurrence of a crack. In the multi-layer ceramic capacitor 1, a silicate crystal made of an oxide including Ba and Si or a silicate crystal made of an oxide including Ti and Si is formed in boundary portions between the laminated block 4 and the ceramic bodies 6.