Multilayer Ceramic Capacitor Electrode Glass Layout for Moisture Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Barium-boron-silicon-based glass used in terminal electrodes of multilayer ceramic capacitors has low moisture resistance, leading to potential penetration of plating solutions and reduced reliability due to reflow defects, while alternatives like bismuth-based glass cause excessive sintering and poor adhesion.
Innovation Solution
Incorporate a conductive paste containing a combination of barium-boron-silicon-based and bismuth-based glasses in the terminal electrodes, with a higher bismuth-to-silicon ratio in the surface-exposed glass domains to enhance moisture resistance and maintain good adhesion to the ceramic body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If barium-boron-silicon-based glass is used in terminal electrodes, then adhesion to ceramic body is improved and reaction layer formation is reduced, but moisture resistance deteriorates and plating solution penetration occurs
Solution Approach 1:
The patent uses a composite glass system combining barium-boron-silicon-based glass (for adhesion) with bismuth-based glass and/or barium-alumino-silicate-based glass (for moisture resistance). This composite approach allows the terminal electrode to simultaneously achieve good adhesion to the ceramic body and high resistance to moisture and plating solution penetration.
2Reliability
If bismuth-based glass is used to improve moisture resistance, then moisture resistance is improved, but excessive sintering occurs and adhesion deteriorates
Solution Approach 1:
The patent controls the spatial distribution of different glass components within the terminal electrode. The barium-boron-silicon-based glass is positioned to provide adhesion at the ceramic body interface, while bismuth-based glass is distributed to provide moisture resistance in regions where it will not cause excessive sintering. This local optimization allows each glass component to fulfill its specific function without adverse effects.
3Strength
If strontium-boron-silicon-based glass or barium-strontium-boron-silicon-based glass is used, then adhesion is improved similar to barium-boron-silicon-based glass, but moisture resistance deteriorates similarly
Solution Approach 1:
The patent combines strontium-containing glass (for adhesion) with bismuth-based glass and/or barium-alumino-silicate-based glass (for moisture resistance). This composite formulation overcomes the individual limitations of strontium-containing glasses by integrating materials with complementary properties, achieving both strong adhesion and high moisture resistance simultaneously.
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 provides improved moisture resistance and adhesion, preventing plating solution penetration and enhancing the reliability of multilayer ceramic capacitors without adverse effects on sintering or adhesion strength.
Implementation Method 1
barium-boron-silicon-based glass prevents or reduces the migration of barium from the ceramic body because of barium includes in the glass, so that a reaction layer is difficult to form
Implementation Method 2
a second glass including a bismuth-based glass, the first glass and the second glass define glass domains in the outer electrode film
Implementation Method 3
drying the conductive paste
Implementation Method 4
firing it at a high temperature to form terminal electrodes electrically connected to inner electrode layers
Data Source
AI summary
In a multilayer ceramic capacitor, an outer electrode film includes a first glass including a barium-boron-silicon-based glass, a strontium-boron-silicon-based glass, or a barium-strontium-boron-silicon-based glass, and a second glass including a bismuth-based glass. The first and second glass define glass domains in the outer electrode film. A glass domain exposed on a surface of the outer electrode film is defined as a first glass domain, and a glass domain exposed on an interface of the outer electrode film with the ceramic body is defined as a second glass domain. A concentration ratio of bismuth to silicon is larger in the first glass domain than in the second glass domain.