Ceramic Capacitor Self-Clearing Lead Connection Design
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Solution Overview
Problem
Conventional lead connection techniques for ceramic capacitors with a benign failure mode can cause dielectric breakdown and catastrophic failure due to the additional thickness of metal at lead connections, which prevents complete vaporization and self-clearing of the electrode material.
Innovation Solution
The capacitor design includes selected areas with additional dielectric material to increase dielectric breakdown voltage and reduce capacitance, preventing dielectric breakdown at lead connections, while maintaining a thin second electrode layer for self-clearing in case of failures, ensuring that defects occur away from the lead connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the top electrode layer is made very thin to enable self-clearing, then complete vaporization can occur during failure isolating the failure to a small area, but multiple lead connections become necessary to safely carry current which increases the risk of dielectric breakdown
Solution Approach 1:
The patent implements local quality by differentiating dielectric thickness between the capacitor's active region and the lead connection regions. The thin dielectric in the active area enables the self-clearing mechanism to function effectively, while the thicker dielectric at lead connection areas compensates for the increased metal thickness from multiple contacts, preventing dielectric breakdown without requiring changes to the thin electrode design
2Reliability
If additional dielectric material is added at lead connection areas, then dielectric breakdown is prevented in the vicinity of lead connections, but the capacitance per unit area is reduced in those areas
Solution Approach 1:
The patent applies local quality by creating spatially varying dielectric thickness: the majority of the dielectric layer maintains uniform thin thickness for high capacitance density, while selected lead connection areas have additional dielectric material providing enhanced breakdown resistance. This localized thickening is strategically placed only where lead connections occur, minimizing the impact on overall capacitance while providing necessary protection against dielectric breakdown at these high-stress regions
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
This design effectively eliminates the risk of dielectric breakdown and catastrophic failure at lead connections, allowing for multiple discrete failure events before significant capacitance loss, maintaining the capacitor's benign failure mode and short-resistance characteristics.
Implementation Method 1
The thinness of the top electrode allows the electrode to melt and vaporize when rapid highly localized temperature increase occurs during a defect failure
Implementation Method 2
The thinness of the top electrode allows the electrode to melt and vaporize when rapid highly localized temperature increase occurs during a defect failure
Implementation Method 3
selected areas of the ceramic dielectric layer include additional dielectric material and exhibit a substantially lower capacitance than the majority of the dielectric layer
Data Source
Figure 1~3
Figure 4~6
AI summary
A capacitor (10) exhibiting a benign failure mode has a first electrode layer (12), a first ceramic dielectric layer (14) deposited on a surface of the first electrode (12), and a second electrode layer (16) disposed on the ceramic dielectric layer (14), wherein selected areas of the ceramic dielectric layer (14) have additional dielectric material (18) of sufficient thickness to exhibit a higher dielectric breakdown voltage than the remaining majority of the dielectric layer (14). The added thickness of the dielectric layer (14) in selected areas allows lead connections (22) to be made at the selected areas of greater dielectric thickness while substantially eliminating a risk of dielectric breakdown and failure at the lead connections (22), whereby the benign failure mode is preserved.