Multilayer Ceramic Capacitor Electrode Layout for Crack-Resistant Soldering
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Solution Overview
Problem
Multilayer ceramic capacitors with low-capacity structures face challenges in high-frequency applications due to weak tensile strength, leading to crack occurrence during soldering, which affects reliability.
Innovation Solution
The ceramic capacitor design includes a ceramic body with stacked dielectric layers, bottom electrodes, a float electrode, and dummy electrodes exposed to the sides, allowing for capacitance adjustment and enhanced tensile strength by facilitating solder rise during soldering, thereby preventing cracks and ensuring stable mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the number of inner electrode stacks is reduced to achieve low capacity and quick response at high frequency, then the response speed is improved, but the tensile strength is weakened and cracks occur during soldering
Solution Approach 1:
The patent divides the electrode structure into multiple segments: bottom electrodes at the base, float electrodes suspended within the dielectric layers, and dummy electrodes extending to side surfaces. This segmentation allows each electrode type to serve specific functions - bottom electrodes provide structural support and electrical connection, float electrodes contribute to capacitance with minimal stress, and dummy electrodes reinforce tensile strength without significantly increasing capacity, thus resolving the contradiction between low capacity and high strength
Solution Approach 2:
The float electrodes act as intermediaries between the bottom electrodes and the dielectric structure. They are spaced apart from side surfaces and overlap only partially with bottom electrodes, providing electrical connection and mechanical support without creating stress concentration points that would lead to cracking during soldering, thereby maintaining both low capacity and high tensile strength
2Quantity of substance
If the number of inner electrode stacks is reduced to achieve low capacity, then the capacitance is reduced for high frequency operation, but the reliability is degraded due to crack occurrence
Solution Approach 1:
The dummy electrodes are pre-positioned to extend from the bottom electrodes to the side surfaces of the ceramic body before soldering occurs. This preliminary structural reinforcement ensures that when soldering stress is applied, the tensile strength is already sufficient to prevent crack occurrence, thereby maintaining high reliability in low-capacity devices
Solution Approach 2:
The patent applies different electrode configurations to different regions of the ceramic body. Bottom electrodes are positioned at the lower surface for electrical connection, float electrodes are positioned centrally within dielectric layers for capacitance contribution, and dummy electrodes are positioned to extend to side surfaces specifically for mechanical reinforcement. This localized differentiation allows the device to achieve low overall capacity while maintaining high reliability through strategic structural reinforcement
3Strength
If dummy electrodes are added to reinforce tensile strength, then the tensile strength is improved, but the device complexity increases
Solution Approach 1:
The dummy electrodes serve multiple functions simultaneously: they extend from bottom electrodes to side surfaces providing tensile strength reinforcement, they are spaced to allow solder rise during soldering processes, and they are positioned to avoid significant capacitance contribution. This multi-functionality allows a single structural element to address multiple requirements without proportionally increasing device complexity
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 design enables the manufacture of ultralow-capacity ceramic capacitors suitable for high-frequency use with improved tensile strength, preventing crack occurrence and ensuring reliable soldering and operation.
Implementation Method 1
An interval between the first and second bottom electrodes and the dummy electrode located at a lowermost part or an interval between the dummy electrodes is an interval at which a solder is able to rise along the dummy electrode during soldering of the first and second bottom electrodes onto a substrate.
Data Source
AI summary
A ceramic capacitor of the present invention comprises: a ceramic body 100 in which a plurality of first dielectric layers 110 are stacked; and first and second bottom electrodes 211 and 212 arranged on both sides of the bottom surface of the ceramic body 100, wherein the plurality of first dielectric layers 110 are formed of only dielectric. The present invention has an advantage of providing a multilayer ceramic capacitor having a low capacity structure to have a high reaction speed while operating at a high frequency.