MLCC External Electrode Anchoring With Ceramic Projection Interface
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Solution Overview
Problem
The adhesion of external electrodes to multilayer ceramic capacitors is weakened due to variations in grain size of the ceramic during firing, leading to gaps between the surface of the multilayer chip and the external electrode, which compromises the adhesion strength.
Innovation Solution
A manufacturing method involving the use of a co-material containing Ba and Ti in the external electrode paste, which diffuses with the dielectric layer's ceramic components during firing, forming a projection portion that enhances adhesion by increasing the contact area between the external electrode and the multilayer chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external electrode paste is applied on the multilayer chip, then electrical connection is established, but adhesion is weakened due to grain size variations during firing
Solution Approach 1:
The patent introduces a projection portion made of co-material (ceramic including at least Ba, Ca and Ti) as an intermediary between the external electrode and the multilayer chip. This projection portion acts as a mediator that bridges the adhesion gap caused by grain size variations, providing a stable anchoring structure that maintains strong bonding despite ceramic shrinkage and grain size changes during firing.
Solution Approach 2:
The projection portion is formed in advance during the firing process before final electrode application. By pre-forming this anchoring structure that protrudes from the multilayer chip surface, the patent creates a prepared interface that ensures strong adhesion when the external electrode is subsequently applied, preventing adhesion failures due to subsequent grain size variations.
2Reliability
If co-material including Ba and Ti is used in external electrode paste, then diffusion occurs during firing, but process complexity increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the external electrode paste by incorporating co-material including specific metal elements (Ba and Ti). This parameter change enables beneficial diffusion during firing that creates strong adhesion. The projection portion's ceramic material composition is specifically designed to match or complement the dielectric layer's ceramic, enabling controlled diffusion that enhances bonding without requiring overly complex multi-component formulations.
3Reliability
If projection portion is formed to increase contact area, then adhesion is improved, but manufacturing precision requirements increase
Solution Approach 1:
The projection portion is formed through self-organization during the firing process. The co-material in the external electrode paste and the projection portion's ceramic material automatically diffuse and reshape under firing conditions to create the optimal projection geometry. This self-forming mechanism reduces the need for precise pre-control of projection dimensions, as the structure naturally optimizes itself during manufacturing to achieve both adequate contact area and proper shape.
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 projection portion provides an anchor effect, resulting in improved adhesion of the external electrodes to the multilayer chip, enhancing the structural integrity and electrical performance of the ceramic electronic device.
Implementation Method 1
a co-material, the end face being an end of the multilayer chip in a direction in which the plurality of internal electrode layers extend; and a projection portion that is provided between the external electrode and the multilayer chip and has a projection shape toward the external electrode from the multilayer chip
Data Source
AI summary
A ceramic electronic device includes a multilayer chip having a plurality of dielectric layers and a plurality of internal electrode layers so as to face each other, each of the plurality of internal electrode layers being stacked via each of the plurality of dielectric layers, an external electrode that is provided on an end face of the multilayer chip, contacts each end of at least a part of the plurality of internal electrode layers, and includes a co-material, the end face being an end of the multilayer chip in a direction in which the plurality of internal electrode layers extend, and a projection portion that is provided between the external electrode and the multilayer chip and has a projection shape toward the external electrode from the multilayer chip. A main component of the projection portion is ceramic including at least Ba, Ca and Ti.