Multilayer Ceramic Capacitor Crack Prevention via Layer Composition
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues due to cracks caused by internal stress from the difference in thermal shrinkage coefficients between ceramic dielectric layers and conductive layers, which are not effectively addressed by existing technologies.
Innovation Solution
The design includes specific dimensions and composition ratios for ceramic dielectric layers and outer electrodes, with increased adhesion forces in outer layer sections and between dielectric and conductor materials, and a manufacturing process that applies sufficient pressure to reduce internal stress and prevent cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional outer layer section designs are used, then manufacturing is simpler, but cracks occur due to internal stress from thermal shrinkage differences
Solution Approach 1:
The patent introduces compositional differentiation between outer and inner layer sections without complicating the overall structure. The outer layer section contains specific oxide compositions and glass content that differ from the inner layer, creating local quality variations that reduce internal stress while maintaining manufacturing feasibility.
Solution Approach 2:
The patent optimizes compositional parameters including glass content (5-20%), SiO2/Al2O3 ratios, and specific oxide concentrations in the outer layer section. These parameter changes reduce thermal shrinkage differences during firing, preventing cracks while keeping the manufacturing process compatible with conventional methods.
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 the occurrence of cracks, enhancing the reliability and yield of multilayer ceramic capacitors by minimizing internal stress through optimized layer dimensions and composition.
Implementation Method 1
cracks occur at the boundary between the multilayer unit and the outer layer section when the body of the multilayer ceramic capacitor is subjected to firing. Unlike the above-described cracks due to an external stress, this type of crack may occur due to an internal stress produced by the difference in the coefficients of thermal shrinkage between the ceramic dielectric layers and the conductive layers when the body of the multilayer ceramic capacitor is subjected to firing.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer unit, thickness-direction first and second outer layer sections, and width-direction first and second outer layer sections. A dimension of the thickness-direction second outer layer section is greater than a dimension of the thickness-direction first outer layer section. The thickness-direction second outer layer section includes an inner portion and an outer portion. A composition ratio of Si to Ti in a ceramic dielectric layer included in the outer portion is higher than that in the inner portion. A Si content ratio is higher in a boundary portion between the outer portion and the inner portion. A relationship expressed by T1/(W0−W1)≦6.95 is satisfied when a minimum dimension in the width direction of the body is denoted by W0, a minimum dimension in the thickness direction of the multilayer unit is denoted by T1, and a minimum dimension in the width direction of the multilayer unit is denoted by W1.