Resin Electrode Layers for Electrolytic Capacitor End-Terminal Adhesion
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Solution Overview
Problem
Existing methods for forming external electrodes on resin molded bodies in electrolytic capacitors face challenges with adhesion due to thermal stress from differing linear expansion coefficients and cannot withstand high-temperature baking processes.
Innovation Solution
The development of electrolytic capacitors with external electrodes comprising a resin electrode layer containing a conductive component and a resin component, formed through screen printing and thermal curing, which provides improved adhesion to the resin molded body and withstands lower-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature baking (600-800°C) is used to form external electrodes on ceramic bodies, then electrode paste can be effectively sintered and adhered, but this method cannot be applied to resin molded bodies due to thermal stress and adhesion failure
Solution Approach 1:
The patent changes the temperature parameter from high-temperature baking (600-800°C) to low-temperature thermal curing (150-260°C), making the electrode formation process compatible with resin molded bodies while maintaining adhesion reliability
Solution Approach 2:
The patent uses a composite electrode paste containing conductive powder (silver, copper, or carbon), resin component, and solvent, which enables adhesion to resin substrates at low temperatures while providing electrical conductivity
2Reliability
If electrode paste is screen printed on resin molded bodies and thermally cured at low temperature, then adhesion is improved, but the process cannot withstand high-temperature reflow soldering due to thermal stress from linear expansion coefficient differences
Solution Approach 1:
The patent modifies the thermal properties of the electrode paste by selecting resin components and conductive powder combinations that have linear expansion coefficients matching the resin molded body, reducing thermal stress during reflow soldering
Solution Approach 2:
The composite electrode paste formulation includes resin components specifically chosen for their thermal expansion characteristics that match the resin molded body, enabling the electrode layer to withstand high-temperature reflow processes without delamination
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 solution enhances the adhesion of external electrodes to the resin molded body, reducing the risk of separation and maintaining electrical integrity during soldering and reflow processes while ensuring uniform thickness and reduced electrical series resistance (ESR).
Implementation Method 1
formed through screen printing and thermal curing
Implementation Method 2
thermal stress is generated due to the difference in linear expansion coefficient between the resin molded body and the electrode layer
Data Source
AI summary
An electrolytic capacitor that includes a resin molded body having opposed first and second end surfaces, the body including a stack that includes a capacitor element with an anode exposed at the first end surface, a dielectric layer on a surface of the anode, and a cathode opposite to the anode and exposed at the second end surface, and a sealing resin that encloses the stack; a first external electrode on the first end surface of the resin molded body and electrically connected to the anode; and a second external electrode on a second end surface of the resin molded body and electrically connected to the cathode, wherein the first external electrode and the second external electrode each include a resin electrode layer containing a conductive component and a resin component.