Laminated Ceramic Capacitor Side Margin Grain Size
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Solution Overview
Problem
Laminated ceramic capacitors face challenges in achieving high capacity due to inaccurate internal electrode alignment and are prone to moisture ingress and thermal shock-induced cracks, which reduce insulation resistance and reliability.
Innovation Solution
Forming a ceramic body on both side faces of a laminate block using dielectric grains with a smaller average grain size than those in the ceramic dielectric layer, improving sintered density and preventing crack generation during thermal shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressure is applied to pressure-bond ceramic green sheets to improve internal electrode alignment, then manufacturing precision improves, but sintering property uniformity deteriorates due to different sintering properties between laminate block and ceramic body
Solution Approach 1:
The patent applies different grain sizes to different regions: fine grains (0.5-5 μm) in the laminate block for high density and electrode alignment, and coarse grains (5-20 μm) in the ceramic body for stress absorption. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The patent creates a composite structure with two distinct ceramic phases: a fine-grained laminate block and a coarse-grained ceramic body. This composite approach allows each material phase to contribute its advantageous properties, resolving the uniformity issue while maintaining overall structural integrity.
2Ease of manufacture
If ceramic body is formed by coating on laminate block to provide side margin, then ease of manufacture improves, but moisture resistance deteriorates due to lower sintered density at side margins
Solution Approach 1:
The ceramic body is specifically designed with coarse grains (5-20 μm) that provide high sintered density (95% or more) and excellent moisture resistance, while maintaining the manufacturing simplicity of coating formation. This local optimization resolves the contradiction between ease of manufacture and moisture resistance.
Solution Approach 2:
The patent changes the grain size parameter in the ceramic body region to be larger than in the laminate block, which fundamentally alters the sintering behavior and results in higher density and better moisture resistance while keeping the coating process simple.
3Reliability
If internal electrodes are formed on ceramic green sheets to increase capacitance, then electrical capacity improves, but reliability deteriorates due to crack generation from thermal expansion mismatch during solder reflow
Solution Approach 1:
The coarse-grained ceramic body is formed beforehand to act as a cushioning layer that absorbs thermal stress during solder reflow. This preventive measure protects the fine-grained laminate block and internal electrodes from crack generation, resolving the contradiction between high capacitance and thermal shock resistance.
Solution Approach 2:
The patent uses a composite material system where the coarse-grained ceramic body provides thermal shock resistance while the fine-grained laminate block provides high capacitance. The interface between these two material phases is designed to manage stress distribution, resolving the contradiction between electrical performance and thermal reliability.
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
Enhances moisture resistance and prevents cracks caused by thermal shock, maintaining insulation resistance and reliability even under high-temperature conditions.
Implementation Method 1
a ceramic body (6), formed on both side faces of the laminate block (4)
Implementation Method 2
many of the ceramic green sheets having an internal electrode formed on it are stacked on top of one another, after which high pressure is applied to pressure-bond the sheets to produce a laminate block
Data Source
AI summary
The laminated ceramic capacitor has a laminate block made of alternately laminated ceramic dielectric layers and internal electrodes, a pair of cover layers, laminated on top and bottom of the laminate block, ceramic bodies formed on both side faces of the laminate block, and a pair of external electrodes that are electrically connected to the internal electrodes, wherein the average grain size of the ceramic dielectric grains constituting the ceramic body is smaller than the average grain size of the ceramic dielectric grains constituting the ceramic dielectric layer in the laminate block.