MLCC Internal Electrode Double Bottlenecks for Moisture Resistance
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in moisture resistance reliability and structural stability, particularly during board mounting, where stress can cause cracks.
Innovation Solution
The multilayer capacitor design incorporates a body with a multilayer structure of dielectric layers and internal electrodes, featuring bottleneck structures on the internal electrodes that increase the distance between the capacitor body and the internal electrodes, enhancing moisture resistance and reducing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer and internal electrode are formed to be thin to implement a smaller multilayer ceramic capacitor, then the capacitor size is reduced, but moisture resistance reliability deteriorates and cracks occur during board mounting
Solution Approach 1:
The patent applies local quality by creating bottleneck structures at specific locations of the internal electrode (where it contacts the dielectric layer) rather than uniformly thinning the entire electrode. This localized structural modification increases the distance between moisture entry points and the internal electrode at critical areas, improving moisture resistance reliability while maintaining the overall thin profile and small size of the capacitor.
2Volume of moving object
If the dielectric layer and internal electrode are formed to be thin to implement a smaller multilayer ceramic capacitor, then the capacitor size is reduced, but cracks occur during board mounting due to stress
Solution Approach 1:
The bottleneck structures are locally formed at the contact regions between the internal electrode and dielectric layer, creating reinforced zones that can better withstand mounting stress. This localized structural enhancement prevents cracks at these critical stress points while maintaining the overall thin design for small capacitor size.
Solution Approach 2:
The bottleneck structures act as pre-formed protective features that cushion against mounting stress before cracks can occur. By increasing the distance between moisture entry points and the internal electrode at these locations, the structure is pre-hardened against the specific stress patterns that occur during board mounting, preventing crack formation.
3Reliability
If bottleneck structures are formed on internal electrodes to increase distance between capacitor body and internal electrodes, then moisture resistance reliability is improved, but capacitance is reduced
Solution Approach 1:
The bottleneck structures are formed only at specific contact regions of the internal electrode rather than uniformly across the entire electrode surface. This localized approach improves moisture resistance at critical entry points while minimizing the reduction in effective electrode area, thereby reducing capacitance loss compared to a uniform thinning approach.
Solution Approach 2:
The patent applies partial action by forming bottleneck structures only where most needed (at contact regions with dielectric layers) rather than across the entire internal electrode. This selective application provides sufficient moisture protection without excessively reducing the electrode area and capacitance.
Data Source
AI summary
A multilayer capacitor includes a body including dielectric layers and internal electrodes and external electrodes disposed on an external surface of the body and connected to the internal electrodes. The body includes a first surface and a second surface to which the internal electrodes are exposed, the first surface and the second surface opposing each other in a first direction, a third surface and a fourth surface opposing each other in a second direction which is a direction in which the dielectric layers are stacked, and a fifth surface and a sixth surface opposing each other in a third direction. At least one of the internal electrodes include a first bottleneck structure having a first directional length of a third-directional outer region smaller than an inner region thereof and a second bottleneck structure having a third directional length of a first directional outer region smaller than an inner region thereof.