MLCC Internal Electrode Structure for Sintering Gap Suppression
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Solution Overview
Problem
The difference in shrinkage behavior between metal and ceramic components during sintering in multilayer ceramic capacitors leads to gaps in internal electrode layers, reducing capacitance and continuity.
Innovation Solution
Dispersing and concentrating small ceramic particles near the center in the thickness direction of internal electrode layers, ensuring that at least 50% or more of the inner ceramic particles are within a specific Dsp range, thereby improving layer continuity and thickness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the internal electrode layers are thinned to achieve higher capacitance and smaller size, then the capacitance and size are improved, but the continuity of the internal electrode layers deteriorates due to excessive grain growth of metal components during sintering
Solution Approach 1:
The patent applies preliminary action by adding ceramic particles (inhibitors) to the conductor paste before the sintering process. These ceramic particles are pre-distributed around the conductive metal particles to control their grain growth during subsequent sintering, preventing excessive grain growth that would occur if the metal particles were left unprotected.
Solution Approach 2:
The patent uses ceramic particles as an intermediary substance between the conductive metal particles. These ceramic particles act as physical barriers that mediate the grain growth process, preventing direct contact and fusion of metal particles while still allowing electrical connectivity through the thin electrode layers.
2Manufacturing precision
If fine ceramic particles (100 nm or less) are used as inhibitors to reduce metal component sintering, then the sintering control is improved, but the uniform arrangement of ceramic particles around conductive metal particles deteriorates due to particle aggregation
Solution Approach 1:
The patent applies parameter changes by carefully controlling the particle size of ceramic inhibitors within a specific range (0.1 μm or less, preferably 0.01 to 0.1 μm). This parameter optimization balances the competing requirements: fine enough to effectively inhibit sintering, but not so fine that aggregation becomes uncontrollable. The patent also adjusts the ratio of ceramic particles to metal particles and controls the firing temperature to achieve optimal distribution.
3Reliability
If ceramic particles are added to conductor paste to inhibit metal sintering, then the continuity of internal electrode layers is improved, but the complexity of paste composition and processing increases
Solution Approach 1:
The patent applies local quality by distributing ceramic particles non-uniformly in a controlled manner - specifically, ensuring that ceramic particles are present around conductive metal particles at critical locations where grain growth control is most needed. The patent specifies that ceramic particles should be present in regions within a certain distance from metal particles, creating locally optimized zones for sintering control rather than requiring uniform distribution throughout the entire paste.
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
Achieves thin and continuous internal electrode layers, along with reduced variation in ceramic layer thickness, enhancing the overall performance and reliability of multilayer ceramic capacitors.
Implementation Method 1
the sintering temperature of the ceramic component is 1000° C. or more, whereas the sintering temperature of the metal component, such as nickel, is lower than 1000° C. and is, for example, 600 to 800° C.
Data Source
AI summary
An internal electrode layer includes therein a plurality of inner ceramic particles within an observation range of a cross-section intersecting the internal electrode layer. The position of the inner ceramic particles in the internal electrode layer relative to the center position of the internal electrode layer in the thickness direction is correlated with the position from the center position to the edge position, and the corresponding positions are indicated by the numbers 0-100. Such an index is referred to as Dsp. Inside the internal electrode layer, within a region of Dsp of 40 or less, preferably 30 or less, the inner ceramic particles are present in an area of at least 50% of the total area of the inner ceramic particles present within the observation range.