Tantalum Powder Flake-Block Structure for Capacitor Performance
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Solution Overview
Problem
Current tantalum powders for capacitors have limitations in achieving high specific capacitance while maintaining low leakage current and loss, with most processes resulting in powders with specific capacitance below 30,000 µFV/g and inadequate pressure resistance.
Innovation Solution
A tantalum powder with a flake + block structure is developed by mixing flaked and granular tantalum powders in specific ratios, followed by milling, water washing, acid washing, and agglomeration, to achieve a specific capacitance range of 30,000 to 80,000 µFV/g and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the average particle size of tantalum powder is reduced to increase specific surface area, then specific capacitance is improved, but pressure resistance deteriorates
Solution Approach 1:
The patent divides the tantalum powder into two distinct size segments: fine particles (0.5-2.0 μm) for high specific capacitance and coarse particles (2.0-5.0 μm) for pressure resistance. This segmentation allows each size fraction to fulfill its specific function, resolving the contradiction between capacitance and mechanical strength
Solution Approach 2:
Different regions of the powder mixture have different particle size characteristics. The fine particles provide high surface area in specific locations to maximize capacitance, while coarse particles are distributed to provide structural integrity and pressure resistance, creating local quality variations that satisfy both requirements
2Strength
If flake tantalum powder is used to increase pressure resistance, then strength is improved, but specific capacitance deteriorates due to volume reduction
Solution Approach 1:
The patent merges flake-shaped tantalum powder (for pressure resistance) with granular tantalum powder (for high specific capacitance) in a composite mixture. This combination allows the flake structure to provide mechanical strength while the granular component maintains high surface area and capacitance, resolving the contradiction between strength and capacitance
3Quantity of substance
If granular tantalum powder is used to maintain high specific capacitance, then electrical performance is improved, but pressure resistance deteriorates
Solution Approach 1:
The patent creates a composite powder material consisting of granular tantalum (providing high specific capacitance) and flake-shaped tantalum (providing pressure resistance). This composite structure combines the advantages of both particle morphologies, allowing the final product to achieve both high electrical performance and adequate mechanical strength
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
The process enhances the specific capacitance, reduces leakage current, and maintains low loss, meeting the requirements for capacitor products in terms of voltage resistance and leakage current, with improved physical properties such as bulk density and particle size distribution.
Implementation Method 1
the main reaction mechanism of the process is shown as follows: Under the argon protection and at a certain temperature, K2TaF7 and liquid sodium take the above reaction
Implementation Method 2
Metal tantalum, being a valve metal, is able to form a dense oxidative film on its surface, so that the metal has the unilateral conduction property
Data Source
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Figure 3
AI summary
A method for providing a tantalum powder with a piece + block structure, comprising the following steps: 1) providing a granulous tantalum powder, and dividing same into a first part and a second part; 2) putting the first part of the tantalum powder in a ball mill for ball milling, taking the powder out after the ball milling and sieving same, and obtaining a tantalum powder in the form of a piece; 3) mixing the tantalum powder in the form of a piece and the second part of the tantalum powder to obtain a mixture, and preferably, the mixing proportion of the tantalum powder in the form of a piece and the granulous tantalum powder being 1:0.1∼1, preferably being 1:0.25∼0.8, and more preferably being 1:0.4∼0.6; and 4) performing the steps of water washing, acid washing, and nodularization on the mixture to finally obtain a tantalum powder with a piece + block structure.