MLCC Bonding Unit Oxide Layer Resists Sintering Stress
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Solution Overview
Problem
Multi-layer ceramic capacitors face issues with cracks or peel-off at the bonded interface of side margins due to differential sintering behavior between metal internal electrodes and ceramic side margins, leading to stress and potential defects during the sintering process.
Innovation Solution
Incorporating a bonding unit made of an oxide with a base metal material, which has a higher strength than unsintered ceramics, between the multi-layer unit and the side margin, with a maximum dimension equal to or larger than 50% of the ceramic layers' average dimension, to enhance bonding strength and resist stress, while also ensuring sufficient area coverage in the bonded interface to prevent cracks or peel-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If side margins are provided to the side surfaces of the multi-layer unit, then the periphery of internal electrodes is protected, but stress is generated between the multi-layer unit and side margins during sintering, causing cracks or peel-off at the bonded interface
Solution Approach 1:
A bonding unit made of oxide containing the base metal material is introduced as an intermediary layer between the multi-layer unit and the side margin. This bonding unit has higher strength than unsintered ceramics and provides resistance to the stress generated during sintering, preventing cracks or peel-off at the bonded interface while maintaining the protective function of the side margin
Solution Approach 2:
The bonding unit is formed as a composite structure consisting of oxide containing the base metal material (such as nickel oxide) with a maximum dimension equal to or larger than 50% of the average dimension of the ceramic layers. This composite material configuration ensures sufficient bonding strength and stress resistance in the bonded interface
2Reliability
If the bonding unit has a maximum dimension equal to or larger than 50% of the ceramic layers, then sufficient area coverage is achieved to resist stress, but the device structure becomes more complex
Solution Approach 1:
The bonding unit's maximum dimension is specifically controlled to be equal to or larger than 50% of the average dimension of the ceramic layers in the first direction. This parameter threshold ensures sufficient area coverage for stress resistance and bonding strength without excessive complexity, providing an optimal balance between reliability and manufacturability
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 bonding unit effectively inhibits cracks or peel-off at the bonded interface by providing higher strength and resistance to stress, even when the ceramic layers are thin, thereby improving the reliability and yield of the multi-layer ceramic capacitors.
Implementation Method 1
the bonding unit is made of an oxide including the base metal material
Implementation Method 2
During sintering of the multi-layer ceramic capacitor, the internal electrodes made of the base metal material start to be sintered at a temperature of several hundred degrees (° C.) and contract in a second direction accordingly
Data Source
AI summary
A multi-layer ceramic capacitor includes a multi-layer unit, a side margin, and a bonding unit. The multi-layer unit includes ceramic layers that are laminated in a first direction, and internal electrodes that are disposed between the ceramic layers and include a base metal material as a main component. The side margin includes ceramics as a main component and covers the multi-layer unit from a second direction orthogonal to the first direction. The bonding unit is disposed between the multi-layer unit and the side margin, the bonding unit having a maximum dimension in the first direction and being made of an oxide including the base metal material, the maximum dimension being equal to or larger than 50% of an average dimension of the ceramic layers in the first direction.