MLCC Cover Layer Geometry for Moisture Resistance Reliability
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Solution Overview
Problem
As multilayer ceramic capacitors (MLCCs) become smaller, moisture permeation from the outside to the internal electrode becomes easier, increasing the possibility of defects, particularly through the edge of the ceramic main body to the end portion of the internal electrode.
Innovation Solution
The MLCC design includes a dielectric layer with first and second internal electrodes and cover layers, featuring a side area with an inclination of 18° to 20° to block moisture penetration paths, and uses a polyvinyl butyral binder with a glass transition temperature of 80° to 90° C. in the dielectric paste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the MLCC size is reduced, then the miniaturization requirement is met, but moisture permeation increases and reliability deteriorates
Solution Approach 1:
The inclined side area is formed in advance during the sintering process by controlling the drying conditions, creating a moisture barrier structure before the product is put into service. This preliminary structural preparation prevents moisture penetration paths from forming later.
Solution Approach 2:
The solution introduces a dimensional change by creating an inclined surface (18° to 20°) on the side area of the MLCC, transforming the traditional flat surface into a three-dimensional structure that effectively blocks moisture penetration paths and improves reliability.
2Volume of moving object
If the MLCC size is reduced, then miniaturization is achieved, but moisture penetration paths form more easily
Solution Approach 1:
The inclined side area structure is prepared in advance during manufacturing, creating a moisture barrier before the product is deployed. This proactive structural design prevents moisture penetration paths from forming in the miniaturized device.
Solution Approach 2:
By introducing an inclined surface geometry (18° to 20°) on the side area, the patent transforms a two-dimensional flat surface into a three-dimensional structure that effectively blocks moisture penetration, addressing the harmful effect of miniaturization.
3Ease of manufacture
If a vertical side area is used, then manufacturing is simple, but moisture penetration is not blocked
Solution Approach 1:
The patent changes the geometric parameter of the side area from a vertical orientation (90°) to an inclined orientation (18° to 20°). This parameter modification maintains manufacturing feasibility while achieving the critical function of blocking moisture penetration paths.
Data Source
AI summary
A multilayer ceramic capacitor including: a dielectric layer; a first internal electrode and a second internal electrode facing each other with the dielectric layer interposed therebetween; and a first cover layer disposed over at least one of the first internal electrode and the second internal electrode, wherein the first cover layer is divided into a center area and a side area disposed outside the center area, and the side area has a surface inclined downward at an inclination of 18° or more and 20° or less with respect to a surface of the center area.