Multilayer Ceramic Capacitor NiO Gradient Peeling Prevention
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Solution Overview
Problem
Conventional multilayer ceramic capacitors experience peeling issues between internal electrodes and dielectric layers due to differing thermal contraction rates during the firing process, particularly affecting the outermost internal electrode and adjacent dielectric layer.
Innovation Solution
Incorporating a multilayer ceramic capacitor design with internal electrodes made of Ni and dielectric layers that include Ti and NiO, where the outer dielectric layer has a higher molar amount of NiO than the inner dielectric layer, reducing grain growth and preventing peeling by maintaining a specific grain size and thickness ratio, and ensuring continuity of internal electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional multilayer ceramic capacitors are manufactured by stacking ceramic green sheets with internal electrodes, then the manufacturing process is simple and cost-effective, but peeling occurs between the outermost internal electrode and the adjacent dielectric layer due to different thermal contraction rates during firing
Solution Approach 1:
The patent applies local quality by creating a gradient in NiO content within the dielectric layer, where the outer dielectric layer has higher NiO content (0.5-2.0 wt%) compared to the inner dielectric layer (0.1-0.5 wt%). This localized compositional variation modifies the thermal contraction characteristics specifically at the outer layer, reducing the thermal contraction rate difference between the outermost internal electrode and dielectric layer, thereby preventing peeling while maintaining the overall manufacturing process simplicity
Solution Approach 2:
The patent changes the chemical composition parameter of the dielectric layer by controlling NiO content distribution. By adjusting the NiO content in the outer dielectric layer to be higher than in the inner layer, the thermal contraction behavior is modified. This parameter change ensures that the thermal contraction rates of the internal electrode and dielectric layer are more closely matched during firing, preventing peeling defects
2Reliability
If the dielectric layer composition is optimized to prevent peeling, then reliability improves, but the manufacturing precision requirements increase due to specific grain size and composition control
Solution Approach 1:
The patent specifies precise parameter ranges to achieve reliable peeling prevention: NiO content in outer dielectric layer (0.5-2.0 wt%), average grain size (180-220 nm), and thickness ratios (outer layer 100-200 μm, inner layer 4-20 μm). These controlled parameters ensure optimal thermal contraction matching and grain growth characteristics during firing, achieving both high reliability and manufacturability within defined specifications
Solution Approach 2:
The patent creates a composite dielectric structure with two distinct layers having different compositions: the outer dielectric layer contains higher NiO content (0.5-2.0 wt%) for peeling prevention, while the inner dielectric layer has lower NiO content (0.1-0.5 wt%). This composite approach allows each layer to perform its specific function - the outer layer prevents peeling through modified thermal contraction, while the inner layer maintains bulk dielectric properties
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
Significantly reduces or prevents peeling between the outermost internal electrode and the dielectric layer, enhancing the reliability and electrostatic capacitance of the multilayer ceramic capacitor by controlling grain growth and maintaining electrode continuity.
Implementation Method 1
the molar amount of NiO with respect to about 100 moles of Ti included in the outer dielectric layer is larger by about 0.6 mole or more than a molar amount of NiO with respect to about 100 moles of Ti included in the inner dielectric layer, and thus grain growth of dielectric grains in the outer dielectric layer is significantly reduced or prevented
Implementation Method 2
since the degrees of thermal contraction of the internal electrodes and the dielectric layers are different at the time of firing, peeling of the dielectric layer, in particular, peeling between an internal electrode located outermost in a stacking direction and a dielectric layer adjacent on an outside thereof may occur
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body in which a plurality of internal electrodes including Ni and a plurality of ceramic dielectric layers are alternately stacked, and external electrodes. The ceramic dielectric layer includes an inner dielectric layer located between internal electrodes, and an outer dielectric layer located outside in a stacking direction and including at least NiO. A difference between average grain sizes of dielectric grains of the outer dielectric layers and the inner dielectric layers is about 10% or less. A molar amount of NiO with respect to about 100 moles of Ti is larger by about 0.6 mole or more in the outer dielectric layer than in the inner dielectric layer.