Multilayer Ceramic Capacitor External Electrodes via Electrolytic Plating
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Solution Overview
Problem
Existing methods for forming external electrodes in multilayer ceramic capacitors, such as electroless plating, result in weak bonding forces, blister formation, and reliability issues due to moisture ingress, and fail to effectively utilize glass particles for adhesion and solder wettability.
Innovation Solution
The use of electrolytic plating films with glass particles dispersed therein, which are coated with a silane coupling agent, to form external electrodes on ceramic bases, ensuring strong bonding and preventing blister formation through heat treatment above the glass softening point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If paste electrode layers are used to form external electrodes, then solder wettability and adhesion are ensured, but the effective volume for electrostatic capacitance is significantly reduced
Solution Approach 1:
The invention changes the formation method of external electrodes from paste application to electrolytic plating, fundamentally altering the deposition parameters. By controlling plating thickness at several micrometers instead of tens to hundreds of micrometers, the effective volume is maximized while maintaining electrical functionality
Solution Approach 2:
The invention uses a composite plating structure with multiple layers (e.g., Ni and Sn) where each layer provides specific functions. The underlying layer prevents solder leaching while the outer layer ensures solder wettability, achieving both requirements without thick paste layers
2Strength
If electroless plating is used to form conductive metal layers, then the bonding force to ceramic surfaces is improved, but blisters are likely to be generated during heat treatment
Solution Approach 1:
The invention replaces electroless plating with electrolytic plating, substituting a chemically-driven process with an electrically-driven one. This substitution eliminates the blister formation issue inherent in electroless plating while maintaining strong bonding through controlled electrochemical deposition
Solution Approach 2:
By changing from electroless to electrolytic plating, the deposition parameters are fundamentally altered. The electrolytic process allows precise control over plating conditions, preventing the blister formation that occurs in electroless plating during subsequent heat treatment
3Strength
If electroless plating is used to co-deposit glass powder with metal ions, then adhesion is improved, but the glass is dissolved or not sufficiently deposited
Solution Approach 1:
The invention replaces electroless plating with electrolytic plating for glass powder deposition. The electrolytic process provides superior control over co-deposition, preventing glass dissolution while ensuring sufficient and uniform deposition through electric field control
Solution Approach 2:
The invention changes the deposition mechanism from chemical reduction to electrochemical deposition. This parameter change enables precise control over glass powder co-deposition, ensuring proper adhesion without the dissolution or insufficient deposition problems encountered in electroless plating
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 approach enhances the effective volume and reliability of ceramic electronic components by providing high bonding force and preventing moisture ingress, while eliminating the need for paste electrodes and reducing the complexity of catalytic treatments.
Implementation Method 1
external electrodes provided on surfaces of the ceramic base body, and the external electrodes include electrolytic plating films including glass particles dispersed therein
Implementation Method 2
glass particles dispersed therein, which are coated with a silane coupling agent
Implementation Method 3
preventing blister formation through heat treatment above the glass softening point
Data Source
AI summary
When external electrodes of a multilayer ceramic capacitor are formed by performing direct plating on surfaces at which internal electrodes are exposed without forming paste electrode layers, bonding forces of plating layers are relatively weak, and in addition, when glass particles are included in the plating layers, blisters are often generated. To overcome these problems, a multilayer ceramic capacitor is formed by performing electrolytic plating using a plating bath including glass particles, electrolytic plating layers including glass particles dispersed therein are formed as the external electrodes.