Multilayer Ceramic Capacitor Electrode Design for Low ESR
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in withstanding mechanical and thermal stresses, leading to increased equivalent series resistance (ESR) and potential cracking, particularly due to the high contact resistance between thermosetting resin and nickel plating layers in existing designs.
Innovation Solution
A multilayer ceramic capacitor design featuring a conductive resin layer with a thermosetting resin and metal composition, applied selectively to the external electrode, reducing coverage of the underlying electrode layer to minimize ESR while maintaining crack prevention effects, with specific exposure ratios and structural features to optimize coverage and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermosetting conductive resin paste is used in the external electrode to prevent cracks under mechanical and thermal stress, then crack resistance is improved, but contact resistance between the resin layer and nickel plating layer increases, leading to increased ESR
Solution Approach 1:
The external electrode is segmented into multiple functional layers: an aluminum paste layer providing mechanical adhesion and crack resistance, a nickel plating layer providing low contact resistance, and a thermosetting conductive resin layer providing environmental stability. This segmentation allows each layer to perform its specific function optimally without compromising the others.
Solution Approach 2:
The patent uses composite material structures where the external electrode combines aluminum paste, nickel plating, and thermosetting conductive resin. This composite approach leverages the strengths of each material: aluminum for adhesion, nickel for conductivity, and thermosetting resin for environmental stability, thereby resolving the contradiction between crack resistance and contact resistance.
2Strength
If a thermosetting resin layer is provided between the electrode layer and nickel plating layer to prevent cracks, then mechanical strength is improved, but equivalent series resistance increases due to high contact resistance
Solution Approach 1:
The thermosetting conductive resin layer is applied locally at specific positions on the external electrode surface, particularly at corners and edges where crack initiation is most likely. This localized application provides mechanical strength where needed while minimizing the overall contact resistance area, thus resolving the contradiction between mechanical strength and ESR.
Solution Approach 2:
The nickel plating layer acts as an intermediary between the aluminum paste layer and the thermosetting conductive resin layer. It provides a low-resistance electrical pathway while allowing the resin layer to provide mechanical protection, thereby mediating between the requirements for strength and low ESR.
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 solution effectively reduces ESR and enhances the capacitors' ability to withstand mechanical and thermal stresses, maintaining crack prevention while optimizing the coverage of the conductive resin layer, thereby improving the capacitors' performance and durability.
Implementation Method 1
the conductive resin layer includes a thermosetting resin and metal
Implementation Method 2
the conductive resin layer disposed on a surface of the underlying electrode layer and including a thermosetting resin and metal
Implementation Method 3
a first plating layer disposed on a surface of the first conductive resin layer
Data Source
AI summary
A multilayer ceramic capacitor includes a laminate and first and second external electrodes that each include first and second underlying electrode layers, first and second conductive resin layers, and first and second plating layers. The first underlying electrode layer includes a portion not covered with the first conductive resin layer on an end surface of the laminate, and the first plating layer is disposed on a surface of the portion of the first underlying electrode layer. The second underlying electrode layer includes a portion not covered with the second conductive resin layer on an end surface of the laminate, and the second plating layer is disposed on a surface of the portion of the second underlying electrode layer.