Capacitor External Electrode Segmentation for Thermal Cracking
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Solution Overview
Problem
Laminated ceramic capacitors face cracking issues due to thermal expansion coefficient differences between ceramic dielectrics and metal external electrode layers, particularly silver, during high-temperature firing processes, leading to product deterioration.
Innovation Solution
The capacitor design includes a divided second electrode layer, a lead wire connected to the second electrode layer within half the capacitor element's height, an exterior resin layer covering the lead wire, and a roughened first electrode layer to reduce the area of the external electrode layer, thereby minimizing thermal expansion-induced distortion and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area of the external electrode layer is increased to increase capacitance, then the capacitance increases, but the distortion due to thermal expansion difference increases causing cracking
Solution Approach 1:
The second electrode layer is divided into a plurality of electrode regions that are separated from each other, reducing the continuous bonding area between the external electrode and ceramic dielectric. This segmentation maintains the total electrode area for capacitance while minimizing the distorted area during thermal expansion, preventing cracking in the ceramic dielectric.
2Quantity of substance
If the area of the external electrode layer is enlarged to increase capacitance, then more capacitance is achieved, but the thermal expansion distortion area increases leading to product deterioration
Solution Approach 1:
The second electrode layer is divided into a plurality of electrode regions that are separated from each other, reducing the continuous bonding area between the external electrode and ceramic dielectric. This segmentation maintains the total electrode area for capacitance while minimizing the distorted area during thermal expansion, preventing cracking in the ceramic dielectric.
3Quantity of substance
If the external electrode layer area is increased to increase capacitance, then capacitance increases, but the bonding area increases causing greater stress during heating
Solution Approach 1:
The second electrode layer is divided into a plurality of electrode regions that are separated from each other, reducing the continuous bonding area between the external electrode and ceramic dielectric. This segmentation maintains the total electrode area for capacitance while minimizing the distorted area during thermal expansion, preventing cracking in the ceramic dielectric.
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
This configuration reduces distortion and prevents cracking, enhancing the reliability of the ceramic capacitors by narrowing the bonding area and applying stress reduction, while maintaining increased capacitance and connection strength.
Implementation Method 1
an oxidation treatment layer 26 formed by an oxidation treatment
Implementation Method 2
the first electrode layer 6-1 may be roughened in a range in which the lead wire is not connected
Implementation Method 3
a lead wire 8-1, 8-2 connected to the second electrode layer 6-2 with solders 10
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A capacitor element (4) having internal electrodes (20) and dielectric layers (ceramic dielectrics 22), the internal electrodes and the dielectric layers being alternately laminated; a first electrode layer (copper electrode layer 6-1) formed on an edge surface of the capacitor element (4) and connected to an internal electrode of the internal electrodes (20); and a second electrode layer (silver electrode layer 6-2) formed into a mesh shape or a dot shape on the first electrode layer (copper electrode layer 6-1) are provided, thereby a product deterioration such as cracking of the ceramic dielectrics due to heating is prevented from occurring by a form of an external electrode layer.